Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Patent
1983-11-29
1985-01-29
Brammer, Jack P.
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
430273, 430281, 430288, 430905, 430538, 430919, 430920, 20415918, 20415923, G03C 168, G03C 500, G03C 524, G08F 250
Patent
active
044966466
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to photosensitive imaging materials, and more particularly to photosensitive imaging materials having a high photographic speed (photographic sensitivity) and halftone reproducibility.
BACKGROUND ART
As one of image-copying techniques, there has been known a method of performing copying by using a photosensitive material which exhibits a change in adhesive properties upon subjected to light. This technique lies on an extension of the photoengraving technique, and copying has been conventionally performed by a sequence of steps of exposing imagewise the photosensitive material to actinic radiation through an original film such as a halftone positive recorded by dot separation according to silver salt photographic technique, etc., to cause a change in tackiness in the exposed areas, and dusting with a pigment. The photosensitive material used in this technique is constructed as a photosensitive film composed of a base film transparent to the actinic radiation and a photosensitive layer tacky at room temperature. The photosensitive layer of this photosensitive film is in turn composed of a uniform composition comprising a polymerization initiator (hereinafter refered to as the "photopolymerization initiator") for photosensitized polymerization, a polymerizable or crosslinkable monomeric compound and a binder comprising a thermoplastic polymer. This photosensitive film is characteristic of exhibiting a significant change in tackiness when exposed to actinic radiation such as ultraviolet rays or the like whose energy density is several mJ/cm.sup.2 -10 mJ/cm.sup.2. This change in tackiness is due to that the photopolymerization initiator of the photosensitive layer is excited by the energy of the actinic radiation and a polymerization or crosslinking reaction of the monomer is brought about, thereby the photosensitive layer is hardened. And, for example, where imagewise exposure of the photosensitive film is performed through an original film such as a halftone positive by using a ultra-high pressure mercury lamp as actinic radiation (ultraviolet radiation) furnishing source on condition that the actinic radiation intensity at the exposed surface is 0.2 mW/cm.sup.2, the image-copying is achieved by several ten seconds exposure.
As described above, in the image-copying technique employing a photosensitive material which exhibits a change in tackiness upon subjected to light, copying is conventionally performed indirectly by employing an original film recorded by dot separation. This is because since this photosensitive material has almost no halftone reproducibility per se, it is necessary to convert the light intensity information of the original film into monochromatic area. Therefore, where this photosensitive material is to be applied to a method of recording a light image directly from a photoimage generating device such as a cathode ray tube which emanates ultraviolet rays, a fiber tube or the like, it is necessary to subject the photoimages to electrical area-converting treatment. As a result, a great loss in the amount of the actinic radiation is caused due to, e.g., attenuation by an optical system employed for image formation. Also, since the light intensity is small in these light image generating devices, an exposure time of several 10.sup.3 hours is required for image recording. Therefore, in this case, it is difficult to obtain a practical photographic speed or resolving power.
DISCLOSURE OF THE INVENTION
An object of this invention is to provide a photosensitive imaging material in which the drawbacks of the conventionally known photosensitive films is improved and has an increased photographic speed, i.e., photographic sensitivity, thereby enabling the imaging in relatively short time. It is another object of this invention to provide a photosensitive imaging material having halftone reproducibility per se.
In the photosensitive imaging material according to this invention, by employing as a photopolymerization initiator, an alloxazine derivative of th
REFERENCES:
patent: 3649495 (1972-03-01), Rust
Brammer Jack P.
Sony Corporation
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