Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2001-01-05
2003-02-04
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S603000, C430S607000, C430S611000, C430S581000, C430S583000, C430S375000
Reexamination Certificate
active
06514683
ABSTRACT:
FIELD OF THE INVENTION
This invention comprises a photographic element containing a fragmentable electron donating compound and having improved sensitivity and improved keeping, in particular improved high temperature keeping fog.
BACKGROUND OF THE INVENTION
Fragmentable two electron donors are compounds that have been designed to undergo a bond fragmentation reaction after capturing the photohole created by absorption of light in a silver halide emulsion. The radical resulting from this bond fragmentation reaction is designed to be sufficiently energetic so as to inject an electron into the silver halide emulsion. Consequently, absorption of one photon by a silver halide emulsion containing a fragmentable two electron donor results in creation of two electrons in the silver halide emulsion, the first resulting from the initial absorption of the photon and the second resulting from the sequence of reactions caused by capture of the photohole at the fragmentable two electron donor. The production of this second electron leads to increased photographic speed. Fragmentable two electron donors have been described in U.S. Pat. Nos. 5,747,235, 5,747,236, 5,994,051, and 6,010,841, 6,054,260 and 6,153,371. These references disclose speed gains associated with the use of fragmentable two-electron donors in a wide variety of silver halide emulsions. Recently, as disclosed in co-pending application Ser. No. 09/755,419 filed Jan. 5, 2001, we have also found that low levels of fragmentable two-electron donors are useful for controlling losses of latent image that may occur between exposure and processing of a multicolor film element. However, it is also frequently found that addition of a fragmentable two-electron donor to an emulsion increases the fog that results when the photographic element is stored at elevated temperatures, called high temperature keeping fog. These fog increases occur in spite of the use of antifoggants such as tetraazaindenes and/or hydroxybenzene compounds to control the fresh fog in the emulsion layers containing the fragmentable two-electron donors. Such high temperature keeping fog increases can limit the ability to use the fragmentable two electron donors as speed or latent image keeping addenda.
PROBLEM TO BE SOLVED BY THE INVENTION
Consequently, it is desirable to find new means to control high temperature keeping fog associated with the fragmentable two-electron donors.
SUMMARY OF THE INVENTION
One aspect of this invention comprises a photographic element comprising at least one light-sensitive silver halide emulsion layer containing a fragmentable electron donating compound of the formula: X—Y′ or a compound which contains a moiety of the formula —X—Y′;
wherein
X is an electron donor moiety, Y′ is a leaving proton H or a leaving group Y, with the proviso that if Y′ is a proton, a base, &bgr;
−
, is present in the emulsion layer, and wherein:
1) X—Y′ has an oxidation potential between 0 and about 1.4 V; and
2) the oxidized form of X—Y′ undergoes a bond cleavage reaction to give the radical X
•
and the leaving fragment Y′; and
3) the radical X
•
has an oxidation potential ≦−0.7V (that is, equal to or more negative than about −0.7V);
said photographic element further comprising a reductone of the Formula 2:
wherein R
23
and R
24
are the same or different, and may represent H, alkyl, cycloalkyl, aryl, or an alkyl group with a solubilizing group such as —OH, sulfonamide, sulfamoyl, or carbamoyl, or R
23
and R
24
may be joined to complete a heterocyclic ring, R
21
and R
22
are H, OH, alkyl, aryl, cycloalkyl, or may together represent an alkylidene group, n is 1 or 2 and R
20
is H, alky, aryl, or CO
2
R
25
where R
25
is alkyl.
In a preferred embodiment of the invention the photographic element comprises a multicolor photographic element comprising a support bearing a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler.
ADVANTAGEOUS EFFECT OF THE INVENTION
This invention provides a multicolor photographic element with improved speed and/or improved latent image keeping characteristics that also has minimal growth of fog (Dmin) at high temperatures.
DETAILED DESCRIPTION OF THE INVENTION
We have found that addition of a reductone compound to a multicolor photographic element containing a fragmentable two-electron donor can significantly improve the high temperature keeping fog associated with the fragmentable two-electron donor. Reductones are known in the art as an addendum for photographic materials, as described for example in Research Disclosure, Item 37038 of February 1995. Hall et al. in U.S. Pat. No. 5,773,208 describe improved latent image keeping behavior of epitaxially sensitized tabular emulsions in the presence of a hexose reductone. In addition, Reynolds et al. in U.S. Pat. No. 5,763,146 describe water soluble reductones that give latent image keeping improvements as well as improvements in speed loss on keeping. Reductones are also discussed in U.S. Pat. No. 2,936,308 and U.S. Pat. No. 3,667,958. The reductones are known reducing agents and can be photographic developers. Thus, it is surprising that these compounds in combination with the fragmentable two-electron donors can actually give less high temperature keeping fog. Further, we have found that the latent image keeping benefits associated with the use of reductones can advantageously be combined with the latent image keeping benefits derived from the use of low levels of fragmentable two-electron donors.
In accordance with this invention the silver halide emulsion contains a fragmentable electron donating (FED) compound which enhances the sensitivity of the emulsion. The fragmentable electron donating compound is of the formula X—Y′ or a compound which contains a moiety of the formula —X—Y′;
wherein
X is an electron donor moiety, Y′ is a leaving proton H or a leaving group Y, with the proviso that if Y′ is a proton, a base, &bgr;
−
, is present in the emulsion layer, and wherein:
1) X—Y′ has an oxidation potential between 0 and about 1.4 V; and
2) the oxidized form of X—Y′ undergoes a bond cleavage reaction to give the radical X
•
and the leaving fragment Y′; and
3) the radical X
•
has an oxidation potential ≦−0.7V (that is, equal to or more negative than about −0.7V).
In this patent application, oxidation potentials are reported as “V” which represents “volts versus a saturated calomel reference electrode”.
In embodiments of the invention in which Y′ is Y, the following represents the reactions that are believed to take place when X—Y undergoes oxidation and fragmentation to produce a radical X
•
, which in a preferred embodiment undergoes further oxidation.
where E
1
is the oxidation potential of X—Y and E
2
is the oxidation potential of the radical X
•
.
E
1
is preferably no higher than about 1.4 V and preferably less than about 1.0 V. The oxidation potential is preferably greater than 0, more preferably greater than about 0.3 V. E
1
is preferably in the range of about 0 to about 1.4 V, and more preferably from about 0.3 V to about 1.0 V.
In this invention the oxidation potential, E
2
, of the radical X
•
is equal to or more negative than −0.7V, preferably more negative than about −0.9 V. E
2
is preferably in the range of from about −0.7 to about −2 V, more preferably from about −0.8 to about −2 V and most preferably from about −0.9 to about −1.6 V.
The structural features of X—Y are defined by the characteristics of th
Johnston Sharon G.
Muenter Annabel A.
Szatynski Steven P.
Baxter Janet
Eastman Kodak Company
Rice Edith A.
Walke Amanda C.
LandOfFree
Photographic element with improved sensitivity and improved... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photographic element with improved sensitivity and improved..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photographic element with improved sensitivity and improved... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3133006