Radiation imagery chemistry: process – composition – or product th – Color imaging process – Using identified radiation sensitive composition in the...
Reexamination Certificate
2002-09-16
2004-06-29
Letscher, Geraldine V (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Color imaging process
Using identified radiation sensitive composition in the...
C430S505000, C430S506000, C430S544000, C430S549000, C430S555000, C430S955000
Reexamination Certificate
active
06756188
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a silver halide photographic element containing a combination of a compound that releases a specific type of electron transfer agent (ETARC) and a compound that releases a specific type of development accelerating agent (DARC) for improved photographic imaging. The ETARC compound releases a specific type of electron transfer agent (ETA) and the DARC compound releases a specific type of development accelerating fragment upon reacting with oxidized developing agent.
BACKGROUND OF THE INVENTION
The sensitivity of widely used silver halide photographic materials has increased over the years from an ISO sensitivity of 100 to an ISO sensitivity of greater than 1000. Emulsions containing large silver halide grains, which give greater sensitivity to light, may be used to increase speed; however, such emulsions usually also increase granularity. In addition, certain silver halide emulsions arc relatively more difficult to develop depending upon their particular physical or chemical properties. For example, silver halide emulsions with large grains or silver halide grains having relatively high iodide content, generally develop at slower rates than emulsions having smaller grains or low iodide content.
Therefore, it is desirable to invent a technique that achieves higher speed with smaller silver halide grains. One way of achieving this is to promote chemical development. Different methods to accelerate development of exposed silver halide grains have been realized.
For example, U.S. Pat. No. 6,110,657 describes the release of improved types of electron transfer agents (ETA)s of limited diffusibility for development acceleration without an increase in ‘wrong-way’ interimage. These types of compounds are commonly referred to as electron transfer agent releasing couplers or (ETARC)s. As another example, U.S. Pat. No. 5,605,786 describes a method of imagewise release of an ETA where an —O—CO—(T)
n
—(ETA) group is attached at the coupling-off site of the ETARC. U.S. Pat. Nos. 4,859,578 and 4,912,025 describe silver halide elements comprising a development inhibitor releasing compound and a compound capable of imagewise releasing an electron transfer agent.
It is also known that couplers that release other types of development accelerating fragments can be used to achieve increased photographic speed. In particular, it is known that compounds that release hydrazine derivatives upon reaction with oxidized developer are effective development accelerator releasing couplers or (DARC)s. For example, U.S. Pat. Nos. 4,482,629; 4,820,616; and 4,618,572 all describe the use of DARCs that release hydrazine derivatives, including those in which the hydrazine derivative also bears a silver absorbable moiety
In spite of all of the efforts in the industry, however, there is still a continuing need for methods of improving the photographic speed of silver halide emulsions without compromising other performance features of the photographic element.
SUMMARY OF THE INVENTION
This invention provides a photographic element comprising a support and at least two silver halide emulsion layers and further comprising an electron transfer agent releasing compound represented by formula (I):
CAR
1
—(L)
n
—ETA (I)
wherein:
CAR
1
is a carrier moiety which is capable of releasing —(L)n-ETA on reaction with oxidized developing agent;
L is a divalent linking group, n is 0, 1 or 2; and
ETA is a releasable 1-aryl-3-pyrazolidinone electron transfer agent having a calculated log partition coefficient (c log P) greater than or equal to 2.40 and the total sum of the Hammett sigma(para) values of the substituents on the 1-aryl ring is 0.51 or less, the ETA being bonded to L or CAR
1
through either the nitrogen atom in the 2-position or the oxygen attached to the 3-position of the pyrazolidinone ring; and a development accelerator releasing compound represented by formula (II):
CAR
1
—(SAM)—NX
1
—NX
2
X
3
(II)
wherein:
CAR
2
is a carrier moiety which is capable of releasing —(SAM)—NX
1
—NX
2
X
3
on reaction with oxidized developing agent;
SAM is a silver absorbable moiety attached to the carrier moiety and is released on reaction with oxidized development agent; and
—NX
1
—NX
2
X
3
is a hydrazine group wherein X
1
, X
2
and X
3
are individually hydrogen or a substituent chosen from alkyl, aryl, carbonyl, or sulfonyl groups with the proviso that at least one of X
1
, X
2
and X
3
is hydrogen.
The photographic elements of this invention exhibit improved photographic speed over that from either the ETARC or DARC alone without compromising other performance features of the photographic element. The improvements in photographic speed in color film elements are unexpectedly synergistic.
DETAILED DESCRIPTION OF THE INVENTION
The ETARCs utilized in the photographic elements of the invention arc represented by formula (I)
CAR
1
—(L)
n
—ETA (I)
ETA is a 1-aryl-3-pyrazolidinone derivative having a calculated log partition coefficient (c log P) greater than or equal to 2.40. using MedChem v3.54 (Medicinal Chemistry Project, Pomona College, Claremont, Calif., 1987). The sum total of the Hammett sigma(para) values of all of the substituents on the 1-aryl ring must be 0.51 or less. The ETA is released from —(L)
n
— and becomes an active electron transfer agent capable of accelerating development under processing conditions used to obtain the desired dye image.
On reaction with oxidized developing agent during processing, the CAR
1
moiety releases the —(L)
n
—ETA fragment which is capable of releasing an electron transfer agent. The electron transfer agent participates in the color development process to increase the rate of silver halide reduction and color developer oxidation resulting in enhanced detection of exposed silver halide grains and the consequent improved image dye density. If the ETA is too mobile, it can diffuse into other layers from where it was originally released and cause increased development in those layers. This results in wrong-way interimage and a decrease in color saturation and purity. The ETA utilized in the invention has a calculated log partition coefficient (c log P) greater than or equal to 2.40 as described above which reduces mobility. However, in some instances the ETA may not be mobile enough to interact efficiently with the developed silver and developer and hence, it is preferred that the c log P of the ETA fragment be no more than 5.0, or more preferably, no more than 4.0 or most preferably, 3.40 or less. Moreover, if the ETA contains substituents with a sum total of Hamett sigma(para) values of greater than 0.51, then the reduction potential of the ETA fragment becomes too low to interact effectively with silver development and/or developer oxidation.
The electron transfer agent pyrazolidinones that have been found to be useful in providing development increases are derived from compounds generally of the type described in U.S. Pat. Nos. 4,209,580; 4,463,081; 4,471,045; and 4,481,287 and in published Japanese Patent Application Serial No. 62-123172, all incorporated herein by reference. Such compounds comprise a 3-pyrazolidinone structure having an unsubstituted or a substituted aryl group in the 1-position. Preferably these compounds have one or more alkyl groups in the 4- or 5-positions of the pyrazolidinone ring.
Preferred electron transfer agents suitable for use in this invention are represented by structural formulas Ia and Ib:
R
2
and R
3
each independently represents hydrogen, a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, CH
2
OR
7
or CH
2
OC(O)R
7
where R
7
can be a substituted or unsubstituted alkyl, aryl or a heteroatom containing group, CH
2
SR
7
, or CH
2
N(R
7a
)(R
7b
) wherein R
7a
, or R
7b
each independently represents hydrogen, or a substituted or unsubstituted alkyl or aryl group. When R
2
and R
3
are alkyl, CH
2
OR
7
or CH
2
OC(O)R
7
groups, and R
7
is a substituted or unsubstituted alkyl or aryl group, it is preferred that R
2
and R
3
comprise from 3
Brick Mary C.
Friday James A.
Keevert John E.
Lushington Kenneth J.
Reed Kenneth J.
Eastman Kodak Company
Letscher Geraldine V
Meeks Roberts Sarah
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