Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied after imaging
Reexamination Certificate
2001-11-27
2003-07-22
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied after imaging
C430S021000, C430S543000, C430S546000, C430S567000, C430S619000, C430S631000
Reexamination Certificate
active
06596470
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver halide color photographic light-sensitive material suited to simple and rapid processing. More specifically, the present invention relates to a simple and rapid processing-type heat-developable light-sensitive material for shooting, which material is excellent in storage stability.
BACKGROUND OF THE INVENTION
Heretofore, processes for forming images by heat development are described in, for example, U.S. Pat. Nos. 3,152,904 and 3,457,075, by D. Klosterboer in “Thermally Processed Silver Systems” (Imaging Processes and Materials, Neblette, 8th edition, edited by J. Sturge, V. Walworth, and A. Shepp, Chapter 9, page 279, 1989). These heat-developable light-sensitive materials contain a reducible non-photosensitive silver source (e.g., an organosilver salt), a catalytically active amount of a photocatalyst (e.g., a silver halide), and a reducing agent for silver, which are ordinarily in a state of dispersion in an organic binder matrix. The light-sensitive materials are stable at normal temperature, but when heated to a high temperature (e.g., 80° C. or above) after exposure, silver is formed through an oxidation-reduction reaction between the reducible silver source (acting as an oxidizing agent) and the reducing agent. This oxidation-reduction reaction is accelerated by a catalytic action of the latent image formed by the exposure. Since the silver produced by the reaction of the reducible silver salt in the exposed area becomes black in contrast with the non-exposed area, thereby to form an image.
On the other hand, the method utilizing a coupling reaction between a coupler and an oxidized product of a developing agent is most common, as a color-image-forming method of a photographic light-sensitive material. JP-A-9-10506 (“JP-A” means unexamined published Japanese patent application) and European Patent No. 762,201 describe methods for forming a color image in a light-sensitive material, wherein a small amount of water is fed to the light-sensitive material, which is incorporated with a developing agent and a coupler, and the light-sensitive material is put together with an image-receiving material containing a base precursor, and these materials are heated, so that a development reaction takes place.
Further, U.S. Pat. Nos. 3,761,270, 4,021,240, 4,426,441, and 4,435,499, JP-A-59-231539, JP-A-60-128438, and the like, describe color heat-developable light-sensitive materials capable of forming an image only by heating, without employing a complex construction involving the use of a base precursor and feeding of a small amount of water. In these patents, p-sulfonamidophenols, p-phenylenediamines, hydrazines, and the like are used as developing agents. Since the coupler before the processing has no absorption in a visible region, the light-sensitive materials according to the coupling method are advantageous in terms of sensitivity. Accordingly, such light-sensitive materials are thought to have the advantage that, beyond use for print materials, they can also be used as photographic materials for shooting.
Ordinarily, a heat-developable light-sensitive material contains a thermal solvent, to raise developing activity. The term “thermal solvent” means an organic material that is a solid at ambient temperature but exhibits a mixed melting point at or below the temperature employed for heat development, on its own, or together with another component, and that liquefies at the time of heat development, so that the heat development and the thermal transfer of a dye are accelerated. Thermal solvents that are known to be useful include a compound capable of becoming a solvent for the developing agent, a compound having a high dielectric constant and capable of accelerating the physical development of a silver salt, and a compound compatible with the binder and capable of swelling the binder.
However, in the case of a heat-developable light-sensitive material, using, as a thermal solvent, a compound that is a liquid at normal temperature, or whose melting point is 100° C. or below, such as an alcohol, a polyol, a phenol, a low-molecular-weight urea or amide, or the like, the thermal solvent itself is hygroscopic or is present in a state of a liquid in the light-sensitive material. Because of this, the light-sensitive material tends to be tacky and is liable to cause a phenomenon that the light-sensitive material adheres to the back surface of another light-sensitive material, or to another material, to thereby cause defective image in some cases. To alleviate this problem, for example, JP-A-60-232547 and JP-A-4-289856 describe the use of a dispersion of fine crystalline particles of a thermal solvent that is a solid at normal temperature, and whose melting point is 50° C. to 180° C.
On the other hand, as to the method for introducing, into a light-sensitive material, a hydrophobic organic substance such as a color-developing agent or a coupler, designed to react with an oxidized product of the color-developing agent, so that a dye is formed, the conventional technique includes the following.
U.S. Pat. Nos. 2,322,027, 4,555,470, and 4,599,296, and JP-B-3-62256 (“JP-B” means examined Japanese patent publication), describe a method comprising dissolving a coupler in a high-boiling-point organic solvent listed therein, or, if necessary, in a mixture of such a high-boiling-point organic solvent and a low-boiling-point organic solvent, whose boiling point is 50° C. to 160° C., and emulsifying and dispersing the resulting solution in a suitable binder.
JP-B-51-39853 and JP-A-51-59943 describe a dispersing method by a polymer.
In the case of a compound substantially insoluble in water, the binder may contain a dispersion of fine particles of the compound, without resorting to the methods listed above.
U.S. Pat. No. 2,870,012 describes a solvent shift method for the preparation of a microdispersion of a color coupler compound containing one or more acid groups (i.e., carboxylic acid or sulfonic acid).
U.K. Patent No. 1,193,349 describes a solvent shift method and a pH shift method in the presence of a protective colloid for dispersing a coupler as an amorphous colloidal dispersion. These methods are applied to a coupler that does not have a sulfonic or carboxylic acid-solubilizing group, and that is soluble in a mixture of an alkaline aqueous solution and an organic solvent compatible with water.
U.S. Pat. Nos. 4,970,139 and 5,089,380 describe a method for preparing a deposited coupler dispersion having an enhanced photographic activity. This method comprises a step in which small particles of a hydrophobic coupler are simultaneously deposited, and the particles take in a water-insoluble coupler solvent, concurrently with the formation of the particles.
U.S. Pat. No. 5,008,179 describes a method for preparing a dispersion, which method comprises preparing a dispersion of an amorphous coupler by pH- and solvent-shifts, and mixing the resulting coupler dispersion with a dispersion of a permanent solvent incorporated with a polymer latex or the like.
U.K. Patent No. 1,570,362 describes micro-grinding methods for preparing a dispersion of solid particles of a photographic additive, such as a coupler, which methods include a sand mill method, a beads mill method, a dyno mill method and related media, a ball mill method, and a roller mill method.
The use of a fine crystalline coupler is effective in reducing the amount of an organic solvent at the time of manufacture. Further, as stated previously, it is known that the coupler can be dispersed as a dispersion of fine crystalline particles. However, a coupler dispersion is not very successfully employed in practical industries of photographic films or print paper elements, because generally the coupler dispersion does not exhibit sufficient reactivity to provide satisfactory image dye densities.
A thermal solvent, which is used in a heat-developable light-sensitive material, is expected to provide the same effect as that of a high-boiling-point solvent, which is used at the time of emul
Kawagishi Toshio
Matsumoto Kazuhiko
Birch & Stewart Kolasch & Birch, LLP
Chea Thorl
Fuji Photo Film Co. , Ltd.
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