Light-sensitive silver halide photographic material

A light-sensitive silver halide photographic material spectrally sensitized with at least one compound of the formula ##STR1## and at least one compound of the formula ##STR2## wherein Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are individually a non-metal atom grouping necessary to complete an unsubstituted or alkyl-, alkoxyl-, phenyl-, hydroxyl-, carboxyl- or halogen-substituted benzene ring, or a non-metal atom grouping necessary to complete a naphthalene ring; Z is a sulfur or selenium atom; n.sub.1, n.sub.2, n.sub.3 and n.sub.4 are individually 2, 3 or 4; M.sub.1 and M.sub.2 are individually a hydrogen atom, an alkali metal atom or H-Q where Q is an organic base.

This invention relates to a light-sensitive silver halide photographic 
material. More particularly, the invention is concerned with a 
light-sensitive silver halide photographic material spectrally sensitized 
with the combination of at least two sensitizing dyes. 
As is well known, supersensitization is such treatment that a major 
proportion of one sensitizing dye is used in combination with a minor 
proportion of a dye or colorless organic compound different in chemical 
structure from said dye, thereby further increasing the color speed of 
photosensitive layer. Sensitizing dyes used in supersensitizing a silver 
halide photographic emulsion in the whole range of visible spectral region 
should satisfy such requirements that: 
1. THEY ARE HIGH IN SPECTRAL SENSITIZING SYNERGISTIC EFFECT, 
2. THEY HAVE SENSITIZING EFFECT IN A PERTINENT SPECTRAL REGION, AND FREE 
FROM DEFICIENCY AT THE GREEN PORTION, 
3. THEY HAVE NO DETRIMENTAL INTERACTIONS WITH OTHER PHOTOGRAPHIC ADDITIVES, 
AND POSSESS STABLE PHOTOGRAPHIC PROPERTIES EVEN DURING STORAGE OF FILMS, 
4. THEY LEAVE NO COLOR STAIN ON FILMS AFTER DEVELOPMENT, AND 
5. THEY HAVE NO DETRIMENTAL EFFECT ON IMAGE QUALITY. 
Heretofore, many combinations of two or more sensitizing dyes have been 
proposed for the supersensitization of silver halide photographic 
emulsions in the whole range of visible spectral region, but those which 
completely satisfy the above-mentioned requirements are less in number. 
That is, some combination forms fog and dye stain when made present 
together with a residual gelatin derivative, which is formed with an 
anionic precipitant, while other combination forms fog and color stain 
when coated on a basic mordant-containing antihalation layer or the like, 
and, in some cases, brings about even degradation in image quality. 
The object of the present invention is to provide a light-sensitive silver 
halide photographic material which has been supersensitized with 
sensitizing dyes, which satisfy the aforesaid requirements, do not form 
any fog and dye stain and are free from deficiency in effect particularly 
at the green portion in the whole range of visible spectral region, and 
which has been improved in image quality. 
As the result of extensive studies, we have found that when the combination 
of at least one compound having the below-mentioned general formula (I) 
with at least one compound having the below-mentioned general formula (II) 
is added to a silver halide photographic emulsion, there are obtained 
excellent photographic properties which have not been attained by the 
conventional processes. That is, we have found that when the combination 
of said compounds is added to a silver halide photographic emulsion, it is 
possible to obtain a light-sensitive silver halide photographic material 
which has been supersensitized over the whole range of visible spectral 
region, is favorable in storability, is less in color stain after 
development, and, moreover, has been improved in image quality. General 
Formula (I) 
##STR3## 
General formula (II) 
##STR4## 
wherein Q.sub. 1, Q.sub.2, Q.sub.3 and Q.sub.4 are individually a 
non-metal atom grouping necessary to complete an unsubstituted or alkyl-, 
alkoxyl-, phenyl-, hydroxyl-, carboxyl- or halogen-substituted benzene 
ring, or a non-metal atom grouping necessary to complete a naphthalene 
ring; Z is a sulfur or selenium atom; n.sub.1, n.sub.2, n.sub.3 and 
n.sub.4 are individually 2, 3 or 4; and M.sub.1 and M.sub.2 are 
individually a hydrogen atom, an alkali metal atom or H-Q (where Q is an 
organic base, for example, pyridine, triethylamine, etc.). 
Typical examples of the compounds having the aforesaid general formulas (I) 
and (II) are enumerated below, but compounds usable in the present 
invention are not limited to these. Typical examples of the compound 
having the general formula (I): 
##STR5## 
Typical examples of the compound having the general formula (II): 
##STR6## 
The compounds having the aforesaid general formulas (I) and (II), of 
course, show spectral sensitizing ability even when used independently. 
When used independently, however, they are not sufficient in sensitizing 
ability, are deficient in effect at the green spectral portion, and show 
no sufficient efficiency when viewed from the standpoint of image quality. 
If the dyes are increased in amount, not only the dye stain after 
development increases but also there is brought about such undesirable 
effect as desensitization or inferior storability. By the combination use 
of the compounds having the general formulas (I) and (II) which cannot 
give any sufficient effect when used independently, excellent sensitizing 
ability, optimum spectral sensitivity and good image quality can 
successfully be displayed. Such synergistic effect derived from the 
combination use of the two compounds has been entirely unexpected. 
Each of the two compounds used in combination in the present invention has 
such characteristics that the two nitrogen atoms constituting heterocyclic 
rings have sulfoalkyl groups as substituents, and the carbon atom at the 
center of the trimethine chain (at the meso-position) has a methyl group 
as a substituent. If the compounds fail to have any of said 
characteristics, no such supersensitization effect as in the present 
invention can be attained. The combination of the dyes according to the 
present invention supersensitizes a light-sensitive silver halide emulsion 
and gives a desirable a spectral sensitivity to the emulsion. Accordingly, 
the supersensitization according to the present invention is effectively 
applicable to all photographic materials including not only ordinary 
photographic materials but also high speed photographic materials, and is 
particularly useful for application to specific photographic materials 
such as microfilms, since the compounds used are free from deficiency in 
effect at the green portion. 
The compounds used in the present invention may be added in the form of a 
solution in water, a water-miscible organic solvent such as methanol or 
the like, or a mixture of said organic solvent with water. The said 
compounds can be added to a silver halide emulsion at any stage during 
preparation of the emulsion. Generally, however, the compounds are 
preferably added immediately after completion of second ripening. The 
amounts of the compounds to be added vary depending on the kind and 
particle size of silver halide. Ordinarily, however, the total amount of 
the compounds having the general formulas (I) and (II) is in the range 
from 100 to 1,000 mg. per mole of silver halide, though this is not 
limitative. At the time of addition to the emulsion, the compounds may be 
used either separately or in the form of a mixture. The silver halide 
emulsion used in the present invention may be any of silver iodobromide, 
silver chloride, silver chlorobromide and silver chloroidobromide 
emulsions. Further, the emulsion may be subjected to noble metal 
sensitization using a gold salt, a palladium salt, a platinum salt or the 
like, sulfur sensitization using a sulfur-containing compound such as 
sodium thiosulfate, sensitization using an amine type compound or 
sensitization using a polyalkylene oxide type compound, and may contain an 
organic or inorganic hardener such as formaldehyde, mucochloric acid, 
glyoxal or chromium alum. Further, the emulsion may contain an surfactant 
such as saponin, sodium alkylbenzenesulfonate or the like as a coating 
aid. It is needless to say that the emulsion may be incorporated with 
other known photographic additives. 
As the support for the light-sensitive silver halide photographic material 
of the present invention, there may be used a cellulose acetate, 
polystyrene, polycarbonate, polyethylene terephthalate or the like high 
polymer film, a glass plate or the like.

The present invention is illustrated in detail below with reference to 
examples, but the invention is not limited to the examples. 
EXAMPLE 1 
A medium speed silver iodobromide emulsion for microfilm containing 2 mole% 
of silver iodide and containing 150 g. of gelatin per mole of silver 
halide was subjected to second ripening with gold sensitization and sulfur 
sensitization. After completion of the second ripening, the compounds 
having the aforesaid general formulas (I) and (II), each in the form of a 
0.2% methanol solution, were added to the emulsion. The amount of each 
compound, per mole of silver halide, was as shown in Table 1. Thereafter, 
the emulsion was incorporated with fixed amounts of a stabilizer, a 
hardener and a spreading agent. This emulsion was coated on a subbed 
cellulose triacetate base to a coated silver amount of 22 mg. per 100 
cm.sup.2, and then dried to prepare a sample. 
Samples prepared in the above manner were individually developed at 
27.degree. C. for 2 minutes with a developer of the composition shown 
below, subjected to ordinary fixing and water-washing, dried and then 
measured in speed to obtain such results as shown in Table 1. In Table 1, 
the speed is a relative value measured when the white light speed of the 
sample containing 300 mg/mole silver halide of the compound (I-10) was 
assumed as 100. Further, the measurement of spectral speed such as 
sensitivity maximum and sensitivity limit was effected by use of a grating 
spectrophotometer (manufactured by Shimazu Seisakusho Co., Ltd.). 
______________________________________ 
Composition of developer: 
______________________________________ 
Metol 1 g. 
Sodium sulfite 75 g. 
Hydroquinone 9 g. 
Sodium carbonate 27 g. 
Potassium bromide 5 g. 
Water to make 1,000ml. 
______________________________________ 
Table 1 
__________________________________________________________________________ 
Relative speed 
Sensi- 
Compound and amount 
White 
Green 
Red tivity 
Sample 
(mg/mole silver halide) 
light 
light 
light 
maximum 
No. Compound (I) 
Compound (II) 
speed 
speed 
speed 
(nm) Fog 
__________________________________________________________________________ 
1 (I-10) 300 mg 
-- 100 7 4 635 0.03 
2 (I-10) 500 mg 
-- 115 9 7 635 0.03 
3 -- (II-5) 300 mg 
110 6 9 645 0.04 
4 -- (II-5) 500 mg 
120 8 11 645 0.04 
5 (I-10) 300 mg 
(II-5) 200 mg 
150 22 18 640 0.03 
6 (I-10) 200 mg 
(II-5) 300 mg 
160 21 22 642 0.04 
7 (I-1) 300 mg 
-- 110 7 3 632 0.03 
8 (I-1) 500 mg 
-- 115 8 6 632 0.03 
9 -- (II-2) 300 mg 
115 6 13 643 0.03 
10 -- (II-2) 500 mg 
140 10 14 643 0.03 
11 (I-1) 300 mg 
(II-2) 200 mg 
150 17 16 635 0.03 
12 (I-1) 200 mg 
(II-2) 300 mg 
160 13 20 635 0.03 
13 (I-3) 300 mg 
-- 105 8 6 630 0.03 
14 (I-3) 500 mg 
-- 110 9 7 630 0.04 
15 -- (II-12) 300 mg 
120 10 9 650 0.04 
16 -- (II-12) 500 mg 
115 7 12 650 0.04 
17 (I-3) 300 mg 
(II-12) 200 mg 
145 14 15 640 0.03 
18 (I-3) 200 mg 
(II-12) 300 mg 
140 12 17 645 0.04 
19 (I-2) 300 mg 
-- 115 12 11 635 0.05 
20 (I-2) 500 mg 
-- 125 14 12 635 0.05 
21 -- (II-9) 300 mg 
130 11 12 645 0.03 
22 -- (II-9) 500 mg 
150 16 13 645 0.03 
23 (I-2) 300 mg 
(II-9) 200 mg 
170 23 20 640 0.04 
24 (I-2) 200 mg 
(II-9) 300 mg 
160 25 26 645 0.04 
__________________________________________________________________________ 
From Table 1, it is understood that the samples according to the present 
invention, which contain the combination of the compounds of the general 
formulas (I) and (II), are far more increased in spectral sensitivity than 
in the case where the said compounds are used independently, have 
excellent spectral sensitivity over the whole range of visible spectral 
region, and are excellent also in other photographic properties. 
EXAMPLE 2 
Samples were prepared and processed in the same manner as in Example 1, and 
then examined in resolving power to obtain such results as shown in Table 
2. As the resolving power test chart, there was used a test chart. 
Table 2 
______________________________________ 
Resolving 
Compound and amount power 
Sample 
mg/mole silver halide (white light) 
No. Compound (I) Compound (II) Lines/mm 
______________________________________ 
25 (I-3) 300 mg -- 200 
26 (I-3) 500 mg -- 210 
27 -- (II-12) 300 mg 
190 
28 -- (II-12) 500 200 
29 (I-3) 200 mg (II-12) 300 mg 
230 
30 (I-3) 300 mg (II-12) 200 mg 
250 
31 (I-4) 300 mg -- 200 
32 (I-4) 500 mg -- 205 
33 -- (II-7) 300 mg 180 
34 -- (II-7) 500 mg 200 
35 (I-4) 200 mg (II-7) 300 mg 240 
36 (I-4) 300 mg (II-7) 200 mg 230 
______________________________________ 
From Table 2, it is understood that by the combination use of the compounds 
of the general formula (I) and (II), there are obtained excellent effects 
in resolving power which cannot be attained when the compounds are used 
independently. 
In this example, it was also confirmed that the samples according to the 
present invention were excellent in spectral sensitivity and other 
photographic properties. 
EXAMPLE 3 
Using the combination of the compound (I-3) with the compound (II-6), an 
emulsion was prepared in the same manner as in Example 1. For comparison, 
another emulsion was prepared in the same manner as above, except that the 
compound (I-3) was replaced by the below-mentioned compound (A) similar in 
structure thereto and the compound (II-6) was replaced by the 
below-mentioned compound silimar in structure thereto. Both the compounds 
(A) and (B) are compounds out of the scope of the present invention. 
##STR7## 
These emulsions were individually coated on the same film base as in 
Example 1 and then dried to prepare samples. The thus prepared samples 
were processed in the same manner as in Example 1 and measured in relative 
speed, sensitivity maximum and resolving power. The results obtained were 
as shown in Table 3. 
Table 3 
__________________________________________________________________________ 
Relative speed 
Sensi- 
White 
Green 
Red tivity Resolving 
Sample 
Compound and amount 
light 
light 
light 
maximum power 
No. (mg/mole silver halide) 
speed 
speed 
speed 
(nm) Fog Lines/mm 
__________________________________________________________________________ 
37 (I-3) 
300 mg -- 105 8 6 630 0.03 
200 
38 (I-3) 
500 mg -- 110 9 7 630 0.04 
210 
39 -- (B) 300 mg 
115 6 8 650 0.04 
190 
40 -- (B) 500 mg 
120 7 650 0.04 
200 
41 (I-3) 
200 mg 
(B) 300 mg 
125 8 10 640 0.04 
200 
42 (I-3) 
300 mg 
(B) 200 mg 
135 10 11 635 0.04 
205 
43 (A) 
300 mg -- 100 7 5 640 0.03 
200 
44 (A) 
500 mg -- 110 8 6 640 0.03 
210 
45 -- (II-6) 
300 mg 
95 6 9 645 0.03 
195 
46 -- (II-6) 
500 mg 
110 7 10 645 0.04 
210 
47 (A) 
200 mg 
(II-6) 
300 mg 
125 9 12 643 0.03 
210 
48 (A) 
300 mg 
(II-6) 
200 mg 
130 10 12 640 0.03 
200 
49 (A) 
200 mg 
(B) 300 mg 
130 9 12 640 0.03 
200 
50 (A) 
300 mg 
(B) 200 mg 
125 9 11 640 0.03 
205 
51 (I-3) 
200 mg 
(II-6) 
300 mg 
145 20 18 643 0.03 
230 
52 (I-3) 
300 mg 
(II-6) 
200 mg 
150 19 19 640 0.03 
240 
__________________________________________________________________________ 
From Table 3, it is understood that when two compounds according to the 
present invention are used in combination, a marked improvement in 
photographic properties can be observed as compared with the case where a 
compound similar in structure to the compounds of the present invention is 
used. That is, if either one of the compounds used in combination is 
replaced by a compound out of the scope of the present invention, such 
excellent effects as in the present invention cannot be obtained any more. 
Further, if the two compounds used in combination are compounds out of the 
scope of the present invention, no such effects as in the present 
invention can, of course, be obtained.