Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified radiation sensitive composition with color...
Reexamination Certificate
2001-06-01
2003-06-03
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified radiation sensitive composition with color...
C430S614000
Reexamination Certificate
active
06573038
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of a certain class of pyrimidine compounds to control fog growth in silver halide photographic elements.
BACKGROUND OF THE INVENTION
The photographic industry is engaged in a continual effort to improve on the stability of its products. Stability can take at least two forms: raw stock stability or latent image stability. Each form of stability is due to a unique interaction between the components of a photographic element. Thus, compounds and processes capable of being utilized to improve one aspect of stability will not necessarily, and often do not, improve other aspects of stability.
When conventional silver halide photographic elements are exposed to actinic radiation, a record of the exposure invisible to the unaided eye is formed. This invisible record of exposure is referred to as a latent image. Formation of the latent image is believed to be the result of the interaction of silver ions with photoelectrons generated by the absorption of actinic radiation by silver halide grains. It is generally agreed that the latent image comprises minute specks of metallic silver formed in, or on, individual silver halide grains. When the exposed silver halide material is processed, a visible image is obtained.
It is known that the latent image is not permanent. The silver specks that form the latent image are metastable, and with the passage of time, they may become undevelopable. This phenomenon is termed latent image fading and manifests itself as a loss in image density in the developed image and a consequent loss in speed in the silver halide photographic material. It is equally plausible that the latent image, may, with the passage of time, grow such that some of the undevelopable silver specks become developable. In this case, the phenomenon is known as latent image gain. This manifests itself in a gain in image density and an increase in an undesirable speed gain.
Latent images of exposed high chloride emulsion photographic materials are prone to change with time if not immediately processed. When exposed color-paper products are left undeveloped, the delay following exposure (which may last from five seconds to thirty minutes) may result in a speed increase. Such increases are variable depending on the duration of the delay before processing. These increases may also vary from one color record to another, resulting in unacceptable color balances. These variabilities could degrade the quality of the image obtained and is a dissatisfier for the consumer. Hence, latent image changes are a significant problem to product builders.
However, latent image changes can be eliminated or substantially reduced by application of known latent image stabilizers, many of which function by mechanisms not completely understood. It is believed that different kinds of latent image stabilizers may function by different mechanisms. U.S. Pat. No. 5,089, 381 describes a class of mercaptotriazole latent image stabilizers and EP 0 377 889 describes a class of triazolomercaptan latent image stabilizers. U.S. Pat. No. 4,378,426 and U.S. Pat. No. 4,451,557 teach the use of alkynyl heterocycles as latent image stabilizing compounds. U.S. Pat. No. 4,948,721 teaches the use of certain benzothiazolium salts for stabilizing photographic latent images in color negative films.
Stabilization also embodies raw stock stabilization, often referred to as storage stability or raw stock keeping (RSK). This form of stabilization typically manifests itself in a photographic element's resistance to fog formation or sensitivity change during prolonged storage, particularly during prolonged storage under conditions of high temperature and relative humidity. Because of the recent increased use in the photographic industry of silver chloride emulsions, which exhibit a greater propensity for storage deterioration than silver bromide or silver iodobromide emulsions, considerable effort has gone into finding effective raw stock stabilizers.
Attempts have been made to improve raw stock stabilization by the addition of inhibitory agents to the silver halide emulsions. These fog-inhibiting agents, however, have often proved inadequate. Examples of raw stock stabilizers are described in U.S. Pat. Nos. 2,772,164; 2,819,965, 2,897,081; 2,919,985; 2,952,539, 2,981,624; 3,051,570; GB 858,326; and JP-A-094626. The compounds in these references generally comprise heterocyclic carboxy- or alkoxycarbonyl-alkyl mercapto structures. Still other forms of stabilizers are known in the art. U.S. Pat. No. 3,791,830, for example, describes the use of arylmercaptoethyl or arylsulfonylethyl esters of carbonthioic acids as antifoggant precursors for stabilizing a photographic element against overdevelopment. U.S. Pat. No. 4,396,707 describes the use of certain aminotriazolomercapto compounds for fog control when processing silver halide photographic element at elevated temperatures. Other alkoxycarbonylmercapto compounds are described in U.S. Pat. No. 5,081,009 and JP 63-046458 as alkali cleavable precursors to mercapto compounds in reversal reflective printing materials, or direct positive internal latent image silver halide emulsions. In U.S. Pat. No. 4,522,917 a photographic element is described which contains a compound capable of undergoing alkali hydrolysis during development to release a photographically useful group comprising an amino moiety. In U.S. Pat. No. 4,952,491 mercaptoazoles or their precursors are described for use in tabular grain emulsions comprising at least about 50 mol % of silver chloride. These compounds, however, have been found to cause a substantial loss in emulsion sensitivity. Despite the myriad forms of stabilizers known in the art, there has yet been provided a sufficiently effective class of stabilizers that are particularly suited for the raw stock stabilization of color negative silver chloride reflective photographic elements.
Few chemicals have the ability to stabilize both the latent image and the raw stock of the silver photographic element. One exception is described in European Patent Application 0 335 107 which discloses the use of polyhydroxy aromatic compounds as suitable for control of raw stock and latent image. Another disclosure, U.S. Pat. No. 5,763,146, teaches the use of water soluble amino hexose reductones for minimizing latent image changes and from raw stock keeping.
Developing agents are chemicals used in the processing of the exposed photographic materials containing the latent image. These agents are known as developers in the photographic trade and are often added to the processing solution for reduction of the silver ion to metallic silver. Hydroxypyrimidines and aminopyrimidines have been reported as useful photographic developing agents (GB 479,446; J. Chem. Soc. (London) 3232 1956, J. Soc. Chem. Ind. London Trans., vol. 60, 313, 1941; U.S. Pat. No. 3,672,891; Photogr. Sci. Eng. vol. 3, 135, 1959, FR 2,065,793). Spectrally sensitized silver halide photographic material for laser exposure and its treatment with hydroxypyrimidinethiol developer has been claimed in JP-09185142. Hydroxymercaptopyrimidines are used in the processing of silver halide photographic materials in JP-06308679. Ruthenium complexes of pyrimidines have been reported to be useful as development accelerators in U.S. Pat. No. 3,964,912. Some of the pyrimidine developing agents exhibit strong reducing properties, i.e., they are readily oxidizable. If added directly to the silver halide emulsion prior to coating, strong reducing agents may reduce silver ion to metallic silver and cause fog, resulting in unacceptable photographic image quality.
Other uses for pyrimidines have also been claimed. Specific aminopyrimidines have been alleged as crystal habit stabilizers of high chloride emulsion grains in European Patent Application 0 430 196. Bisaminopyrimidine derivatives have been described for use in photographic films in JP 89-150264 and JP 89-117117. The use of metal complexes of pyrimidines in silver halide photographic emulsions with improved sensitivity-fog r
Chen Shihua S.
Lok Roger
Martinez Alberto M.
Russell Dean H.
Eastman Kodak Company
Meeks Roberts Sarah
Schilling Richard L.
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