Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-04-19
2001-03-27
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S531000, C430S619000
Reexamination Certificate
active
06207364
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermally developable material, in detail, to a thermally developable material which is colorless, transparent and excellent in repetitive size accuracy, and specifically to a thermally developable material for plate-making suitable for color printing.
BACKGROUND OF THE INVENTION
Conventionally, in the printing plate-making field, solution waste generated along with the wet process for image forming materials has caused problems. In recent years, in terms of environmental protection and space saving, a decrease in processing solution waste has been strongly demanded. Accordingly, a technique for a photo-thermal photographic material has been desired for application to photographic techniques in which effective exposure is possible employing a laser image setter, and a clear and sharp black image with high resolution can be formed. As such techniques, several methods are well known, which are described, for example, in U.S. Pat. Nos. 3,152,904 and 3,487,075, as well as in D. Morgan, “Dry Silver Photographic Materials”, (Handbook of Imaging Materials, Marcel Dekker, Inc.) page 48, 1991, and the like. Because these photographic materials are commonly developed at a temperature of at least 80° C., they are called thermally developable materials.
The thermally developable material forms images employing a thermal development and comprises photosensitive silver halide, a non-photosensitive reducible silver source (an organic silver salt), a reducing agent for the silver source and a silver toning agent if necessary, usually in a form of dispersion in an (organic) binder matrix. When a developable material for printing plate-making is employed for color printing, a plurality of film sheets, which are subjected to color separation for each color, are usually employed. These are printed onto each of the machine plates; the resulting plates are superimposed, and employed for printing. When film sheets which are subjected to a plurality of color separation are not precisely superimposed, a phenomenon called doubling occurs. Therefore, with developable materials for printing plate-making, it is important that the sizes are always identical after development, that is, repetitive accuracy is required.
However, when the thermally developable material described above is developed at a temperature of not less than 80° C., conventionally, the above-mentioned repetitive size accuracy has not been sufficient, and when employed in color printing, they are not commercially viable. To overcome this problem, is described in Japanese Patent Publication Open to Public Inspection No. 10-10671 a technique in which resins such as polycarbonates, polyimides, etc., which tend not to be thermally contracted, are employed to prepare a support, instead of using conventionally employed polyethyleneterephthalates. This invention has been proven to assure the repetitive size accuracy. However, it has been found that when polyimide resin is used, as it is, to prepare a support, the developable material itself results in a brown tint, which is not commercially viable.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention has been accomplished. An object of the present invention is to provide a thermally developable material for printing plate-making, which is colorless and transparent, excellent in repetitive size accuracy, and suitable for color printing.
The present invention and embodiment thereof are described below.
A thermally developable material of the invention comprises a support both surfaces which are covered with a resin thermal shrinkage ratio of not more than 0.02% at 150° C. for 30 minutes, and an image forming layer comprising an organic silver.
A thermally developable material comprising a plastic support in which both surfaces are covered with a polyimide resin.
A thermally developable material comprising a plastic support in which both surfaces are covered with a resin containing water soluble group.
The resin containing water soluble group is a resin which comprises preferably at least one of polyimide structure and cyclo ring.
The thickness of the covering layer comprised of the polyimide resin on each side is preferably 0.25 to 4 &mgr;m.
The thermally developable material preferably comprises a photosensitive layer containing an organic silver salt and silver halide grains on the support.
The thermally developable material comprises a plastic support in which both surfaces are preferably covered with a resin having thermal shrinkage ratio of not more than 0.02% at developing temperature.
The resin to be coat the plastic film preferably has glass transition point not more than the developing temperature.
In the another embodiment, the resin may not have glass transition point, or have glass transition point not less than 100° C.
In the other embodiment, the resin is an inorganic and organic hybrid material containing silica. The hybrid material is preferably a polymer containing organosilsesquioxane unit or silicate unit in a structure.
The thickness of the resin coat in one side is preferably 0.25 to 4 &mgr;m.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
Thermally developable materials are described in detail, as described above, for example, in U.S. Pat. Nos. 3,152,904 and 3,457,075, as well as in D. Morgan, “Dry Silver Photographic Material”, D. Morgan and B. Shely, “Thermally Processed Silver Systems”, (Imaging Processes and Materials), Neblette, 8th edition, edited by Sturge, V. Walworth, and A. Shepp, page 2, 1969, etc.
The thermal developable material is stable at room temperature and is developed by heating at high temperature after exposure. Silver image is formed by redox reaction between organic silver salt (works as an oxidant) and reducing agent caused by heating. The reaction goes on without providing processing liquid such as water from outside. The heating temperature is preferably 80 to 200° C., more preferably 100 to 150° C. Keeping these temperature, sufficient image density can be obtained within a short time, transportation is smooth without fusing binder. The thermal developable material may be processed by preheating at 50 to 80° C. just before the heat development. Term for development is preferably 10 to 60 seconds. Term for preheating is preferably 5 to 60 seconds.
The thermal developable material is thermally developed in the following way. The thermal developable material is transported between a heat drum which comprises heating devise having diameter not less than 200 mm and a transportation belt provided against the drum or device comprising several auxiliary transportation drum having diameter of 10 to 50 mm provided along with the heating drum keeping the image forming side contact with the heating drum in a heat insulating chamber. Or the thermal developable material is transported through a device having plurality of rollers positioned alternatively or in opposite position in a heated by heating means in a heated thermally insulating chamber, or the device comprising above mentioned rollers which comprises heating means by itself.
The support employed in the present invention is a film in which both surfaces of a plastic support are covered with a resin having thermal shrinkage ratio of not more than 0.02% at 150° C., 30 minutes. It is preferable that the resin is polyimide resin. The polyimide resin is a resin formed by condensation of acid dianhydrides and diamines, and is known to be a heat resistant resin. In the present invention, block polyimide resins and polyisoimide resins are preferably employed due to their ease in machining. Further polyimide resin containing cyclo ring compound in the structure component is preferably employed because it improves transparency.
The block polyimide resins are those which are prepared in such a manner that at least two of each of acid dianhydrides and diamines, which are resin components, are paired and block-polymerized. The preparation methods and the like are described in Japanese Patent
Habu Takeshi
Takamuki Yasuhiko
Usagawa Yasushi
Bierman Jordan B.
Bierman, Muserlian and Lucas
Chea Thorl
Konica Corporation
LandOfFree
Thermally developable material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermally developable material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermally developable material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513422