Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1994-12-22
2004-05-25
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S603000, C430S611000
Reexamination Certificate
active
06740482
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to color photographic emulsions particularly those comprising tetradecahedral silver chloride iodide grains comprising less than 5 mole % iodide.
BACKGROUND OF THE INVENTION
In the manufacturing of color negative photographic printing papers, at least three light sensitive emulsion layers are used to capture the photographic image, i.e., red, green, and blue. Frequently, the blue sensitive emulsion is placed at the bottom of the light sensitive multilayer coating pack. In this layering order, less light is available to the bottom blue layer because of the light scattering and absorption occuring in the layers above.
The incandescent lamp used for exposing the paper is low in its energy output in the short wavelength region (blue) of the visible spectra. This further reduces the energy impinging on the blue layer.
The color negative film through which the light is exposed onto the photographic paper has a yellowish brown tint (as a result of the processing used for development). This yellowish background filters out blue light causing a further diminution of blue light arriving at the bottom layer.
Still, in recent developments in the art of manufacturing color photographic paper, there is a need to improve the color reproduction of the original scene as captured in the color negative film. One way of achieving such an improvement is to employ a shorter blue spectral sensitizing dye that better matches the blue sensitization of the original film (U.S. Ser. No. 245,336 filed May 18, 1994). As a result, the sensitivity of the blue emulsion is further pushed towards the shorter wavelength region where less light energy is available.
Consequently, there exists a need to manufacture a blue sensitive emulsion that has a high sensitivity (speed) in order to overcome the light deficiency and to capture the fidelity of the original color image.
Photofinishers also desire short processing times in order to increase the output of color prints. One way of increasing output is to accelerate the development by increasing the chloride content of the emulsions; the higher the chloride content, the higher the development rate. Furthermore, the release of chloride ion into the developing solution has less restraining action on development compared to bromide, thus allowing developing solutions to be utilized in a manner that reduces the amount of waste developing solution.
Additionally, it is highly desirable that color negative printing papers have speed characteristics that are invariant with exposure time. This feature allows their usage in a wide variety of applications, including high speed printers, easel printing, and other electronic printing devices. To accommodate this variety of exposing devices, the emulsions used in the color negative papers must be capable of recording the exposure between the exposure range of nanoseconds (1×10
−9
seconds) to several minutes while maintaining printing speed and contrast. But emulsions with high-chloride content are usually less efficient, with relative efficiency being worse at high intensity-short time exposures. Therefore, there is a need for high-chloride emulsions with high sensitivity that exhibit little loss in speed at extremely short exposure times.
Another factor to be considered when designing a color paper is print quality such that it is pleasing to the eye both in color and contrast. A color paper with high contrast gives saturated colors and rich details in shadow areas.
It is known in the art that the greater reducibility and developability of silver chloride relative to silver bromide or iodide emulsions make silver chloride emulsion highly susceptible to fog formation. Thus, it is extremely critical when using silver chloride emulsions of high sensitivity that this fog be restrained.
It is also known in the art that when fog is generated in the precipitation stage, certain agents can be added during the grain-forming process to reduce the undesirable minute silver clusters that constitute this fog. These agents include hydrogen peroxide, peroxy acid salts, disulfides (U.S. Pat. No. 3,397,986), mercury compounds (U.S. Pat. No. 2,728,664), iodine (EP 576,920), iodide releasing agents (EP 563,708, EP 562,476, EP 561,415, and JP 06,011,784) and p-quinone (U.S. Pat. No. 3,957,490).
The use of thiosulfonate compounds for controlling fog during precipitation has been claimed in the following U.S. patents: U.S. Pat. Nos. 5,061,614; 5,079,138; 5,244,781; 5,185,241; and 5,229,263. Likewise, in the following European applications, EP 368,304; EP 434,012; EP 435,355; and EP 435,270, the use of thiosulfonates during grain formation of AgX emulsions is claimed.
For high chloride emulsions, U.S. Pat. No. 4,960,689 discloses the use of thiosulfonates in the finish. It also claims the use of thiosulfonates in combination with sensitizing dyes in high chloride emulsions. Aromatic thiosulfonic acids are disclosed in U.S. Pat. No. 5,009,992 as supersensitizers in an IR-sensitive high Cl emulsion. EP 495,253 discloses the use of thiosulfonates in the sensitization of high chloride emulsions along with Au(III) and thiocyanate salts.
Combination of thiosulfonates with sulfinates and nucleating agents are taught to be useful in U.S. Pat. No. 5,110,719 in a direct positive internal latent image core/shell ClBr emulsion. U.S. Pat. No. 5,292,635 discloses the use of thiosulfonates and sulfinates in controlling speed increase on incubation of color photographic materials. The combination of thiosulfonates with sulfinates has been alleged to be useful in the sensitization of chloride emulsions for color paper in JP 3,208,041. U.S. Pat. No. 2,394,198 discloses the use of sulfinates with thiosulfonates in stabilizing silver halide emulsions. U.S. Pat. No. 2,440,206 teaches the use of the combination of sulfinates, along with small amounts of polythionic acids to stabilize photographic emulsions against fog growth. U.S. Pat. No. 2,440,110 teaches the use of the combination of sulfinates with aromatic or heterocyclic polysulfides in controlling fog growth. A combination of iodate ions and sulfinates have been claimed by Fuji to be useful in preventing yellow fog in silver halide materials. The use of sulfinates has been disclosed to reduce stain in photographic paper when used in combination with sulfonates in US Statutory Invention Registration H706, and in EP 305,926.
Alkyl and aryl disulfinates have been disclosed for use in the formation pre-fogged direct positive silver halide emulsions in U.S. Pat. No. 5,043,259. U.S. Pat. No. 4,939,072 discloses the use of sulfinates as storage stability improving compounds in color photographs. In U.S. Pat. No. 4,770,987 sulfinates are disclosed as anti-staining agents, along with a magenta coupler in silver halide materials. EP 463,639 teaches the use of sulfinic acid derivatives as dye stabilizers. The use of a paper base which has been treated with a sulfinic acid salt has been disclosed in U.S. Pat. No. 4,410,619 to prevent discoloration of the photographic material. Aromatic sulfinates are alleged to be useful as stabilizers in a direct positive photographic material in U.S. Pat. No. 3,466,173. In EP 267,483, sulfinates are added during the sensitization of silver bromide emulsions. Similarly, G.B. 1,308,938 alleges the use of sulfinates during processing of a silver halide photographic material to minimize discoloration of the image tone. Sulfinates are claimed to have fog reducing properties in U.S. Pat. No. 2,057,764.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a continuing need for high chloride emulsions that have improved sensitivity. Further, there is a need for emulsions that will provide higher contrast when utilized in photographic elements. Further, there is a continuing need for improved finishing materials to provide increased sensitivity without fog increase to new iodochloride grain types.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a photosensitive material that can be rapidly processed.
Another object of the
Chen Benjamin Teh-Kung
Lok Roger
Blank Lynne M.
Eastman Kodak Company
Leipold Paul A.
Letscher Geraldine
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