Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-03-13
2001-07-03
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
Reexamination Certificate
active
06255045
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to photographic elements containing an improved class of polymeric scavengers for oxidized developer.
BACKGROUND OF THE INVENTION
It is known in the art to add a scavenger for oxidized developer to a photographic element in order to prevent oxidized developing agent from reacting within the element at an undesired location or at an undesired point in time. In particular, it is undesirable for oxidized developer to diffuse away from the imaging layer in which it formed and into other color records where it can form dye in the wrong layer. In some formats early formation of dye can have an undesirable impact on tone scale and fog formation. Typically, scavengers reduce or eliminate oxidized developers without forming any permanent dyes. They also do not cause stains nor release fragments that have photographic activity. They are also typically rendered substantially immobile in the element by incorporation of an anti-diffusion group (a ballast) or by attachment to a polymer backbone. Mobility of an oxidized developer scavenger within the film element is undesirable because it may scavenge the oxidized developer in a layer where the oxidized developer is required; i.e. in an imaging layer. Ideally, the scavenger should be present only in those areas of the film element where the presence of oxidized developer is detrimental.
Known scavengers for oxidized developers include ballasted para hydroquinone (1,4-dihydroxybenzene) compounds such as described in U.S. Pat. No. 3,700,453 or U.S. Pat. No. 4,732,845; ballasted gallic acid (1,2,3-trihydroxybenzene) compounds as described in U.S. Pat. No. 4,474,874; ballasted resorcinol (1,3-dihydroxybenzene) compounds as described in U.S. Pat. Nos. 3,770,431 and 5,856,072; ballasted hydrazides such as described in U.S. Pat. No. 4,923,787 and ballasted pyrocatechol (1,2-dihydroxybenzene) compounds as described in U.S. Pat. Nos. 4,175,968, 5,561,036 and German Patent No. 766,135 and couplers which do not form permanent dyes such as those described in U.S. Pat. No. 5,932,407.
Such known materials are insufficient in their activity and require high material usage, thus increasing cost, storage and handling concerns. High material usage also requires thicker layers which degrade sharpness through increased scatter pathlength. In addition, because some of these known materials are sensitive to oxidative conditions, they are often insufficiently stable upon long term storage. Finally, many of these materials form stains or colored residues during processing. Therefore, it is desirable to find scavengers for oxidized developers that have high activity, have excellent stability upon long-term storage and do not leave colored residues after processing.
Disulfonamidophenyl scavengers for oxidized developing agents are described in U.S. Pat. No. 4,447,523. Ballasted sulfonamidophenols as scavengers for oxidized electron transfer agents are described in U.S. Pat. No. 4,205,987. Polymeric sulfonamidophenols as scavengers are described in U.S. Pat. No. 4,717,651. A particular deficiency associated with the use of sulfonaminophenols as scavengers in photographic systems is that they can cause increased sensitizing dye stain. Sensitizing dyes are ordinarily intended to be washed out or otherwise removed from the photographic element during processing. However, in many cases sensitizing dye is not fully removed but is retained in the photographic element after processing. This leads to a non-imagewise increases in Dmin because the retained sensitizing dye is colored (although shifted in hue). In particular, red sensitizing dyes often exist in two forms in photographic elements, monomeric (magenta colored, □max=580 nm) and aggregated (cyan colored, □max=640 nm). Normally, retained red sensitizing dye exists in its monomeric form (magenta colored) and leads to non-imagewise increases in green density. In the presence of a sulfonamidophenol compound, retained red sensitizing dye can aggregate and become cyan colored. After development, there is a positive image in residual sulfonamidophenol. In areas of the element where there is no exposure, there is no oxidized developer to consume the scavenger, whereas at areas of high exposure, all of the sulfonamidophenol is consumed. Thus, the retained red sensitizing dye will form a corresponding positive image in its aggregated form (cyan in color) along with the corresponding positive scale in red density. This causes an undesirable increase in red Dmin and an effective loss in red contrast and speed when the red Dmin is adjusted back to the aim level. This deficiency is a particular problem whenever high levels of red sensitizing dyes are used, as is commonly the case with tabular silver halide emulsions and other emulsions with high surface area. It is also a particular problem with sensitizing dyes that are especially prone to aggregate in the presence of a sulfonamidophenol.
Known sulfonamidophenol scavengers are still deficient in this area U.S. Pat. No. 5,478,712 describes a combination of a disulfonamidophenol scavenger with ballasted amines of high basicity to avoid sensitizing dye stain which is an improvement, but not to the necessary degree.
It is the object of this invention to provide a novel photographic element containing a polymeric disulfonamidophenol scavenger of oxidized developer that is active, inexpensive, and oxidatively stable. The scavenger must not produce unwanted stains after processing and should have no photographic effects other than the scavenging of oxidized developer.
SUMMARY OF THE INVENTION
This invention provides a photographic element comprising a support, a radiation sensitive silver halide emulsion layer and a water dispersible polymeric disulfonamidophenol that is substantially immobile in the element. The photographic elements of the invention exhibit improved stability, color reproduction and robustness in terms of processing variations. Particularly the photographic elements of the invention have fewer variations in red density due to sensitizing dye.
DETAILED DESCRIPTION OF THE INVENTION
The polymeric disulfonamidophenol utilized in the invention may be any disulfonamidophenol polymer which is suitable for use in a photographic element and which is water dispersible and substantially immobile in the photographic element as described hereafter. In one embodiment the water dispersible disulfonamidophenol polymers of the invention have repeating units according to Formula A:
wherein:
R is hydrogen or an alkyl or aryl group; L is a divalent linking and X is a disulfonamidophenol. They can also be described as being derived from a monomer defined by the following general formula (A′):
where R, L and X are the same as for (A).
L is a divalent linking group that permanently attaches X to the polymeric backbone. Preferably L is —O—, —S—, —NH—, —Ch
2
—, —SO
2
— or a substituted or unsubstituted carbonyl or aryl group, or combinations thereof, containing 1 to 20 carbon atoms. Preferred linking groups are represented by Formulas L-1 and L-2:
where Q is —O—, —S—, —NH—, —CO—, —Ch
2
—, —SO
2
NH— or —SO
2
—. Examples of particularly preferred linking groups according to Formula L-1 are —CONH— and —CO
2
—. Especially preferred linking groups according to Formula L-2 are linking groups in which Q is a sulfonamido group in which the nitrogen is attached directly to X. There may be optional groups or atoms, such as alkylene groups, that attach Q to X. Some examples of these extended linking groups would be —CONHCH
2
CH
2
CONH—X, —CO
2
CH
2
CH
2
—X, —CONHCH
2
CH
2
—O—Ch
2
CH
2
NHCO—X, etc.
X is a derivative of a disulfonamidophenol which is defined as a phenol or napthol nucleus substituted with at least two sulfonamido (—NHSO
2
—) groups in which the —NH of the sulfonamido groups is attached directly to the phenol or napthol nucleus. The disulfonamidophenol can also be represented either by Formula X-a or X-b:
The preferred structure of the disulfonamidophenol is according to Formula X-1:
wherein
R
1
and R
2
Chen Tien-teh
Leone Ronald E.
Singer Stephen P.
Eastman Kodak Company
Le Hoa Van
Meeks Roberts Sarah
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