Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-06-02
2001-12-11
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S577000, C430S578000, C430S584000, C430S588000, C430S591000, C430S600000, C430S613000, C430S614000, C430S615000, C430S944000
Reexamination Certificate
active
06329135
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to thermally developable silver halide photothermographic materials, and an image recording method and image forming method by use thereof, and in particular spectrally sensitized silver halide photothermographic materials exhibiting enhanced sensitivity, reduced variation in sensitivity after pre-exposure storage and improved silver image tone, and an image recording method and an image forming method by use thereof.
BACKGROUND OF THE INVENTION
Spectrally infrared-sensitizing dyes in general are inferior in adsorption to silver halide grains, compared to spectral sensitizing dyes in the visible region, producing problems such as low sensitivity and marked reduction of sensitivity following storage. As a means for overcoming such problems, JP-A (hereinafter, the term, JP-A means an unexamined and published Japanese Patent Application) discloses a technique of using specified infrared sensitizing dyes in combination with a heteroatom containing macrocyclic compound. However, it is not only insufficient in improving effects but also concerns conventional silver halide photographic materials, and further nothing is described therein with respect to thermally developable photosensitive materials. Further, the preferred silver halide composition is taught to be silver chlorobromide. Therefore, when such techniques are applied to thermally developable silver halide photothermographic materials, problems were produced such as:
(1) insufficient prevention of desorption of sensitizing dyes from silver halide grains during storage of coated film, and
(2) sensitizing dyes being easily decomposable, leading to reduced sensitivity and increased fogging.
Accordingly, it is difficult to apply this technique to thermally developable photosensitive materials. Binders used in thermally developable photosensitive materials are different from those used in conventional silver halide photographic materials, and therefore adsorption of spectrally sensitizing dyes used in the thermally developable photosensitive materials are also different from the binder matrix of gelatin in conventional silver halide photographic materials. Therefore, it is necessary to apply a method suitable thereto and to realize that the technique described above is not applicable as such. Although such phenomena are marked in infrared-sensitizing dyes, similar problems are likely produced in sensitizing dyes in the visible region.
On the other hand, the need for infrared-sensitive thermally developable photosensitive materials is strong and thermally developable photosensitive materials improved in defects described above are highly desired.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to provide a thermally developable silver halide photothermographic material with enhanced sensitivity and which exhibits reduced desensitization during pre-exposure storage.
It is a second object of the invention to provide a thermally developable silver halide photothermographic material giving images improved in silver image tone., light stability and heat stability.
Further, it is a third object of the invention to provide an image recording method and an image forming method by use of the silver halide photothermographic materials described above.
The above problems can be accomplished by the following items 1. through 8.:
1. A silver halide photothermographic material comprising a support having thereon a light-sensitive layer and light-insensitive layer, wherein the light-sensitive layer or the light-insensitive layer comprises a heteroatom-containing macrocyclic compound, and the light-sensitive layer comprises a sensitizing dye exhibiting maximum sensitivity at a wavelength of 600 nm or more;
2. The silver halide photothermographic material described in 1. above, wherein the sensitizing dye is represented by the following formula (1), (2) or (3):
wherein Z
1
represents an atomic group necessary to form a 5- or 6-membered nitrogen-containing heterocyclic ring; D and D′ each represent an atomic group necessary to form an acyclic or cyclic acidic nucleus; R
1
represents an alkyl group; L
1
, L
2
, L
3
, L
4
, L
5
, L
6
, L
7
, L
8
, L
9
and L
10
each represent a methine group, provided that each may form a ring together with other methine group(s) or with an auxochrome; n1, n2, n3, n4 and n5 are each 0 or 1; M
1
represents a counter ion necessary to neutralize-charge; and m1 is the number of 0 or more, which is necessary to counterbalance intramolecular charge,
wherein Z
1
, Z
2
and Z
3
each represent an atomic group necessary to form a 5- or 6-membered nitrogen-containing heterocyclic ring; R
1
and R
3
represent an alkyl group; R
2
represents a hydrogen atom , an alkyl group, an aryl group or a heterocyclic group; L
1
, L
2
, L
3
, L
4
, L
5
, L
6
, L
7
, L
8
, and L
9
each represent a methine group; p1 and p2 are each 0 or 1; n1 and n2 are each 0, 1, 2, 3 or 4; M
1
represents a charge balancing counter ion; and m1 is the number of 0 or more, which is necessary to counterbalance intramolecular charge,
wherein Z
4
, Z
5
and Z
6
each represent an atomic group necessary to form a 5- or 6-membered nitrogen-containing heterocyclic ring; R
4
represents an alkyl group; R
5
and R
6
represent a hydrogen atom , an alkyl group, an aryl group or a heterocyclic group; L
10
, L
11
, L
12
, L
13
, L
14
and L
15
each represent a methine group; p3 is 0 or 1; n3 and n4 are each 0, 1, 2, 3 or 4; M
2
represents a charge balancing counter ion; and m2 is the number of 0 or more, which is necessary to counterbalance intramolecular charge;
3. The silver halide photothermographic material described in 1. above, wherein the sensitizing dye represented by formula (2) is represented by the following formula (4):
wherein Z
7
is the same as defined in Z
1
of formula (2), Z
8
is the same as defined in Z
2
of formula (2) and Z
9
represents an oxygen atom, a sulfur atom or a selenium atom; R
7
is the same as defined in R
1
of formula (2), R
8
is the same as defined in R
2
of formula (2) and R
9
is the same as defined in R
3
of formula (2); L
16
is the same as defined in L
1
of formula (2), L
17
is the same as defined in L
2
of formula (2), L
18
is the same as defined in L
3
of formula (2), L
19
is the same as defined in L
4
of formula (2), L
20
is the same as defined in L
5
of formula (2), L
21
is the same as defined in L
6
of formula (2), and L
22
is the same as defined in L
7
of formula (2); p4 is the same as defined in p1 of formula (2); n5 is the same as defined in n1 of formula (2) and n6 is the same as defined in n2 of formula (2); M
3
is the same as defined in M
1
of formula (2); m3 is the same as defined in m1 of formula (2); Q represents an alkyl group, an aryl group or a heterocyclic group; k1 is 1, 2, 3 or 4;
4. The silver halide photothermographic material described in 1, 2 or 3, wherein light-sensitive silver halide contains overall iodide of 0.01 to 10 mol %;
5. The silver halide photothermographic material described in 1, 2, 3 or 4, wherein binder of the light-sensitive layer is mainly comprised of a polymeric latex;
6. An image recording method, wherein a silver halide photothermographic material described in any one of 1 to 5 above is exposed by using a laser exposure apparatus, in which scanning laser light is not exposed at an angle substantially vertical to the exposed surface of the photothermographic material;
7. The image recording method described in 6, wherein the photothermographic material is exposed by using a laser exposure apparatus, in which scanning laser light is longitudinally multiple;
8. An image forming method, wherein a silver halide photothermographic material is thermally developed in a state having a moisture content of 0.01 to 5.0% by weight.
DETAILED DESCRIPTION OF THE INVENTION
Infrared sensitizing dyes, as described above, are generally weak in adsorption and inferior in storage stability after spectral sensitization of photothermographic materials, producing problems such that
Bierman Jordan B.
Bierman, Muserlian and Lucas
Chea Thorl
Konica Corporation
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