Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified radiation sensitive composition with color...
Reexamination Certificate
2001-12-11
2003-01-14
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified radiation sensitive composition with color...
C430S607000, C430S611000, C430S598000, C430S617000
Reexamination Certificate
active
06506548
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to silver halide photographic materials containing solubilized antifoggants. More specifically it relates to non-photothermographic silver halide materials containing solubilized antifoggants.
BACKGROUND OF THE INVENTION
Problems with fogging have plagued the photographic industry from its inception. Fog is a deposit of silver or dye that is not directly related to the image-forming exposure, i.e., when a developer acts upon an emulsion layer, some reduced silver is formed in areas that have not been exposed to light. Fog can be defined as a developed density that is not associated with the action of the image-forming exposure, and is usually expressed as “D-min”, the density obtained in the unexposed portions of the emulsion. Density, as normally measured, includes both that produced by fog and that produced as a function of exposure to light. It is known in the art that the appearance of photographic fog related to intentional or unintentional reduction of silver ion (reduction sensitization) can occur during many stages of preparation of the photographic element including silver halide emulsion preparation, spectral/chemical sensitization of the silver halide emulsion, melting and holding of the liquid silver halide emulsion melts, subsequent coating of silver halide emulsions, and prolonged natural and artificial aging of coated silver halide emulsions. The chemicals used for preventing fog growth as a result of aging or storage are generally known as emulsion stabilizers.
The control of fog, whether occurring during the formation of the light-sensitive silver halide emulsion, during the spectral/chemical sensitization of those emulsions, during the preparation of silver halide compositions prior to coating on an appropriate support, or during the aging of such coated silver halide compositions, has been attempted by a variety of means. Mercury-containing compounds, such as those described in U.S. Pat. Nos. 2,728,663; 2,728,664; and 2,728,665, have been used as additives to control fog. Thiosulfonates and thiosulfonate esters, such as those described in U.S. Pat. Nos. 2,440,206; 2,934,198; 3,047,393; and 4,960,689, have also been employed. Organic dichalcogenides, for example, the disulfide compounds described in U.S. Pat. Nos. 1,962,133; 2,465,149; 2,756,145; 2,935,404; 3,184,313; 3,318,701; 3,409,437; 3,447,925; 4,243,748; 4,463,082; and 4,788,132 have been used not only to prevent formation of fog, but also as desensitizers and as agents in processing baths and as additives in diffusion transfer systems.
However, despite all the efforts in this field there still remains a need for compounds which act as effective antifoggants in photographic elements which are stored under high temperature conditions. There is particularly a need for antifoggants which are water soluble and, thus, are safer to utilize during manufacture of the photographic elements.
SUMMARY OF THE INVENTION
This invention provides a silver halide photographic element comprising at least one silver halide emulsion layer and further comprising an antifoggant represented by the following Structure I:
wherein R
1
is an aliphatic or cyclic group, R
2
and R
3
are independently hydrogen or bromine as long as at least one of them is bromine, L is a divalent linking group, m and n are independently 0 or 1, and SG is a solubilizing group with a pKa of 8 or less. This invention further provides silver halide emulsions comprising said antifoggants.
The photographic elements of this invention demonstrate reduced fogging during chemical sensitization and enhanced fog retardation of liquid emulsions during high temperature holding. The water soluble antifoggants minimize the need for expensive and time-consuming preparation of solid-particle dispersions, as well as minimize the need for volatile organic solvents. Use of these materials also eliminates the need to use environmentally undesirable heavy metal antifoggant salts such as mercuric salts.
DETAILED DESCRIPTION OF THE INVENTION
The silver halide photographic elements of this invention include one or more water-soluble or water-dispersible antifoggants containing a solubilizing group with a pKa of 8 or less. These compounds are represented by the following Structure I:
wherein R
1
is a substituted or unsubstituted aliphatic or cyclic group of any size as long as the antifoggant remains soluble or readily dispersible in water. Substituted or unsubstituted aliphatic groups for R
1
include monovalent groups having 1 to 20 carbon, nitrogen, sulfur, and oxygen atoms in the chain including, but not limited to, chains that include one or more substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted alkenylene groups having 2 to 20 carbon atoms, substituted or unsubstituted alkylenearylene groups having 7 to 20 carbon atoms in the chain, and combinations of any of these groups, as well as combinations of these groups that are connected with one or more amino, amido, carbonyl, sulfonyl, carbonamido, sulfonamido, thio, oxy, oxycarbonyl, oxysulfonyl, and other connecting groups that would be readily apparent to one skilled in the art. The various types of useful aliphatic groups would be readily apparent to one skilled in the art. Preferred aliphatic groups for R
1
include substituted or unsubstituted t-butyl groups and trifluoromethyl groups.
R
1
can also be substituted or unsubstituted cyclic groups including substituted or unsubstituted carbocyclic aryl groups having 6 to 14 carbon atoms to form the cyclic ring, substituted or unsubstituted cycloalkylene groups (having 5 to 10 carbon atoms to form the cyclic ring), and heterocyclic groups (having 5 to 10 carbon, nitrogen, sulfur, or oxygen atoms to form the cyclic ring), both aromatic and non-aromatic. The various types of cyclic groups would be readily apparent to one skilled in the art.
Preferred cyclic groups for R
1
include substituted or unsubstituted aryl groups having 6 to 10 carbon atoms to form the cyclic ring. Substituted or unsubstituted phenyl groups are most preferred. Methyl groups are preferred substituents on the phenyl group.
In Structure I, R
2
and R
3
are independently hydrogen or bromine as long as one of them is bromine. Preferably, both R
2
and R
3
are bromine.
In addition, L is a substituted or unsubstituted divalent linking group, and more preferably an aliphatic linking group that can have the same definition as R
1
except that L is divalent. Thus, one skilled in the art would be able to determine suitable L groups that would serve the desired purpose while maintaining compound water solubility or dispersibility. Preferably, L is —NH-alkylene wherein “alkylene” is substituted or unsubstituted and has 1 to 10 carbon atoms (more preferably 1 to 3 carbon atoms).
Substituents on R
1
and L can be any chemical moiety that would not adversely affect the desired function of the antifoggant and can include, but are not limited to, alkyl, aryl, heterocyclic, cycloalkyl, amino, carboxy, hydroxy, phospho, sulfonamido, sulfo, halo, and other groups that would be readily apparent to one skilled in the art. The number of substituents is limited only by the number of available valences (available hydrogen atoms). Alkyl groups are preferred substituents for cyclic R
1
groups. However, as would be apparent, the antifoggants can have multiple sulfo, carboxy, phospho, and sulfonamido groups that impart water solubility to the molecule. Further, in Structure I, m and n are independently 0 or 1, and preferably, both are 1.
SG can be any suitable solubilizing group which has a pKa of 8 or less and which does not interfere with the antifogging activity of the compound. SG may be in the free acid form or it may be a salt, particularly a suitable metal (for example, alkali metal salt) or ammonium ion salt. Preferably, SG is a salt. When SG is in its free acid form, the salt can be generated in situ by neutralization with any basic material commonly used by one skilled in the art. Preferably SG is a carboxy, phospho, s
Burgmaier George J.
Eikenberry Jon N.
Grzeskowiak Nicholas E.
Klaus Roger L.
Mydlarz Jerzy Z.
Eastman Kodak Company
Meeks Roberts Sarah
Schilling Richard L.
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