US3718475A

US3718475A - Silver halide supersensitized photographic emulsion

Info

Publication number: US3718475A
Application number: US00049981A
Authority: US
Inventors: K Shiba; A Sato
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1969-06-25
Filing date: 1970-06-25
Publication date: 1973-02-27
Anticipated expiration: 1990-02-27
Also published as: FR2052878A5; GB1293862A; BE752386A; DE2031491A1; JPS4838406B1

Abstract

A silver halide photographic emulsion is super-sensitized in the green wave length region by adding thereto at least one sensitizing dye of the following formula I and at least one sensitizing dye of the following formula II; and, optionally a compound of the following formula III:

Description

United States Patent n91 Shiba et al.

[ 1 SILVER HALIDE SUPERSENSI'IIZED PHOTOGRAPHIC EMULSION [75] Inventors: Keisuke Shiba; Akira Sato, both of Ashigara-Kamigun, Kanagawa, Japan [73] Assignee: Fuji Photo Film Co., Ltd.,

Kanagawa, Japan [22] Filed: June 25,1970 21 Appl.No.: 49,981

[30] Foreign Application Priority Data June 25, 1969 Japan ..44/50l17 v [52] U.S.Cl ..96/124, 96/139 [51] Int. Cl. ..G03c 1/14 [58] Field of Search ..96/ 124 [56] References Cited UNITED STATES. PATENTS 2,533,427 l2/l950 Carroll ..96/l24 2,541,400 2/l95l Brooker et al..... ..96/l20 2,701,198 2/l955 Carrolletal. ....96/l24 3,038,800 6/1962 Lucltey eta] ..96/l39 Primary Examiner-J. Travis Brown Attorney-Sughrue, Rothwell, Mion, Zinn and Macpeak 51 Feb. 27, 1973 [57] ABSTRACT A silver halide photographic emulsion is super-sensitized in the green wave length region by adding thereto at least one sensitizing dye of the following formula I and at least one sensitizing dye of the following formula ll; and, optionally a compound of the following formula III:

FORMULAI N N I i a i Z I CCII=CIICII:C J Z2 f Ra 4 FORMULA II i m y W 011:0 m

w 5 Its amt-1 FORMULA III is C=CH-CN=NZu 1'1,

The substituents are described in detail hereinbelow.

22 Claims, No Drawings SILVER I'IALIDE SUPERSENSITIZED PHOTOGRAPl-IIC EMULSION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a super-sensitized silver halide photographic emulsion and more particularly it relates to -a supersensitized silver halide photographic emulsion for increasing particularly the spectral senl emulsion containing couplers for making color photographic light-sensitive materials.

2. Description of the Prior Art It is well known that a spectral sensitizing method is one of the techniques employed in the manufacture of silver halide photographic emulsions, and that the sensitizing method is an indispensible technique for the production of color photographic light-sensitive materials. The spectral sensitivity obtained by the method is influenced not only by the chemical structure of the sensitizing dye to be used and the properties of the silver halide emulsion to be used, such as the composition of the halogen and the crystal system ofthe silver halide contained in the emulsion, the manner of chemical ripening, the silver ion concentration and the hydrogen ion concentration of the emulsion, but also by the various kinds of additives added to the silver halide emulsion.

In many cases, the spectral sensitivity is reduced. However, when a certain kind of sensitizing dye is used together with a dye or a colorless aromatic compound having a specific chemical structure according to the chemical structure and the properties of the sensitizing dye, a higher spectral sensitivity is obtained than when using each of the sensitizing dyes alone. This is known as a super-sensitizing action.

In particular, silver halide emulsions used for producing color photographic light-sensitive materials contain a large amount of couplers, and when a coupler is incorporated in a silver halide photographic emulsion containing a sensitizing dye, the spectral sensitivity becomes lower than the spectral sensitivity obtained by using the sensitizing dye alone. In addition, the presence of the coupler reduces the super-sensitizing action.

Also, the spectral sensitivity distribution in the green region, in which mans visual sensitivity is high, is one of the most important factors for the color reproduction of color photographic light-sensitive materials and for the quality of the image obtained.

Therefore, various studies have been made concerning the sensitization of silver halide emulsions in the green region. For example, a method of using a combination of a benzimidazolocarbocyanine dye and a pseudocyanine dye is described in the specification of U. S. Pat. No. 2,701,198. However, when the method described in the aforementioned U. S. patent is applied to a silver halide emulsion containing a coupler, only a low sensitivity is obtained due to the presence of the coupler in the emulsion.

Also, a method of using a combination of a benzimidazolocarbocyanine dye and a benzoxazolocarbocyanine dye is described in the specification of Japanese Pat. Publication No. 4936/68. However, this method has the disadvantages that the sensitivity in the shorter wave length side of the green region, e.g., in a wave length region of 500-530 mp. is large, and also the contamination effect by the dyes after development is large.

Therefore, a primary object of the present invention is to provide a silver halide photographic emulsion having both a high spectral sensitivity in a wave length region of 500-530 my. and less of a contamination by the dyes after development.

Another object of the present invention is to provide a silver halide photographic emulsion used for producing a color photographic light-sensitive material having a high green sensitivity in the presence of a coupler.

SUMMARY OF THE INVENTION The above objects of the present invention can be attained by super-sensitizing a silver halide photographic emulsion with at least one sensitizing dye represented by the following formula I:

FORMULA I wherein R and R, (which may be same or different) each represent an alkyl group, an aryl group or a substituted alkyl group; R and R, (which may be same or different) each represent an alkyl group, an aryl group or a substituted alkyl group (including a substituted alkyl group having a sulfo group); at least one of said R and R being a substituted alkyl group having a sulfo group; Z and Z, (which may be same or different) eachrepresents a non-metallic atomic group necessary to complete a heterocyclic nucleus of the benzimidazole series; X,- represents an acid anion group usually employed in cyanine dyes; and p is an integer of 1 or 2, p being 1 when the cyanine dye of formula I forms an intermolecular salt; and at least one of the sensitizing dyes represented by the following formula II:

FORMULA II R5( 2 )ql l wherein Z, represents a non-metallic atomic group necessary to complete a heterocyclic nucleus of the 2- quinoline series; Z, represents a non-metallic atomic group necessary to complete a benzoxazole nucleus, a naphthoxazole nucleus, a benzthiazole nucleus, a benzselenazole nucleus, a naphthothiazole nucleus, or a naphthoselenazole nucleus, each being unsubstituted or substituted by an alkyl group, a phenyl group, a halogen atom, an alkoxyl group or an alkoxyl group having a sulfo group; R and R, (which may be same or different) each represents an alkyl group or a substituted alkyl group (including a substituted alkyl group having a sulfo group); at least one of said R and R being a substituted alkyl group having a sulfo group except where the heterocyclic nucleus containing Z has been substituted by a substituted alkoxyl group having a sulfo group; X represents an acid anion group usually employed in cyanine dyes; and q is an integer of in the above-mentioned formula II may be, for example, 2-quinoline and 2-quinoline containing, as a component of the skeletal-structure thereof, a benzene ring substituted by at least one of the following: an alkyl 1 or 2, q being 1 when the cyanine dye of formula II 5 group and a halogen atom. forms an intermolecular salt. The substituted alkyl group of R in the above-men- Furthermore, it has been discovered according to the tioned formula III is, for example, a sulfoalkyl group present invention that a particularly better result is obneutralized by a cation, such as alkali metal ions, ortained by incorporating a compound represented by ganic ammonium ions, a pyridinium ion, a benzylthiouthe following formula III in the above-mentioned silver m ronium ion, and the like, usually employed in cyanine halide photographic emulsion: dyes, a cyanoalkyl group and an allyl group.

As X and X in the formulas I and II, there maybe il- FORMULA In lustrated, e.g., a halogen, perchlorate, thiocyanate, ptoluene sulfonate, benzene sulfonate, methyl sulfate and ethyl sulfate ions.

I The sensitizing dye represented by formula II has at 7 least one sulfo group in the heterocyclic nucleus conwherein R represents an alkyl group or a substituted taimng R5 or '.T Spectral sensltlzanon 0balkyl group; Z represents a non-metallic atomic group gamed by 1 .sensmzmg dye rePresemed. by the necessary to complete a heterocyclic nucleus of the omula ordmanly reduced ihemtroduct'on ofa benzimidazole series; and Z represents a phenyl group sulfo group but.when the sensmzmg y represented by the formula I 15 used together therewith, the spectral or a substituted phenyl group, such as a phenyl group sensitization is increased substituted by alkyl groups, alkoxy groups, and the like. The sensitizing y represented y the formula II DETAILED DESCRIPTION OF THE PREFERRED y be Substituted therein y an alkyl p. a p y EMBODIMENTS group, a halogen atom, an alkoxyl group, or an alkoxyl group substituted by at least a sulfo group; in other In the formulas I and the alkyl words, the substituent is so selected that the maximum groups of R1 to R6 f methyl ethyl "'P sensitivity obtained by using at least one sensitizing dye Pf and lso'butyl groups; and as the of formula II and at least one compound of formula I in smuted alkyl groups of 1 to e there y be combination does not shift to a longer wavelength side "med: y group, aralkyl group, a l y' than that of the sensitizing dye of formula II. ethyl group, a 'Y' yp py group, a Y- The compound represented by formula III shows a YP Py p a B' y y group, a Y- super-sensitizing action to the sensitizing dye sulfatopropyl group, a s'sulfatobutyl group, a represented by formula I and to the sensitizing dye acetylsulfamyl g p and a B y y Y 8 "P- represented by formula II, and by using the compound In Particular, as the Substituted alkyl group having 3 represented by formula III together with the combina- Su fO gr up, t e e may be illust ated a fi-sulf p opyl tion of the other two sensitizing dyes, the green seng p, fiy g p. a 5-Sulf0buty1 g p. 3 40 sitivity is further increased and at the same time the p p y) y g p, a p p xsensitivity in the wave length region of 500-530 MA, y) yl y g p, d a Z-hydroxy-l-sulfopropyl which is present at a shorter wave length side of the S P' green region, is further increased.

As the benzimidazole series nucleus completed by The compounds which may be used in the present in- Z,, Z, or 2,, there may be illustrated: benzimidazole vention will be further illustrated by reference to the and benzimidazole containing, as a component of the following illustrative formulas, which are merely illusskeletal-structure thereof, a benzene ring substituted trative, and not limiting, in nature. by at least one of the following: a halogen atom, an N- unsubstituted or alkyl substituted sulfamyl or carbamyl (IA) 0 H C H group, an N-disubstituted sulfamyl group such as a Cl 2 5 5 morpholino sulfonyl group, an alkyl sulfonyl group, a trifluoromethyl group, an unsubstituted or substituted c-oII=c1I-CII=C I alkyl group, a cyano group, a phenyl group, a carboal- I v/ koxyl group, a hydroxyl group, and an alkoxyl group. -W

Also, the 2-quinoline series nucleus completed by 2;, 0 (01mm)? CHzCHz-O CHzCHa-O CHsCHa-SOJ The above-mentioned sensitizing dyes or the other compounds which may be used in this invention may be synthesized by known methods.

For instance, they can be synthesized by the methods described in the specifications of U. 8. Pat. Nos. 2,503,776 and 2,778,823; Belgian Pat. Nos. 590,607; 704,296; 668,014; 669,133; 669,934; 673,554; and 697,006; British Pat. Nos. 742,112; 955,964; 975,504; and 980,234; Japanese Pat. Publication Nos. 14112/65; 23467/65; and 13823/68; and Japanese Pat. Application Nos. 55439/67 and 76071/67.

Also, other sensitizing dyes and the compounds used in this invention, which were not described above, may also be easily synthesized by referring to the specifications of the above patents.

The compounds used in this invention are incorporated in a sliver halide emulsion as solutions in water or a water-soluble organic solvent such as methanol, ethanol, and pyridine. The sensitizing dyes represented by formulal and formula 11, respectively, may be added to a silver halide emulsion as a mixture of the solutions thereof or as separate solutions. The amounts of these dyes are greatly influenced by the nature of the silver halide emulsion to be used. Usually the total amount of the above-mentioned sensitizing dyes (1 and 11) and compound 111 are preferably from 1 X mol to 1 X 10 mol, per mol of silver halide. The weight ratio of the amount of the sensitizing dye represented by formula II to the amount of the sensitizing dye represented by formula I is preferably from 10:1 to 1:2, but this ratio is varied by the amount of the compound represented by formula III to be added.

As the silver halide emulsion which may be used in this invention, there may be illustrated: a silver iodobromide emulsion, a silver bromide emulsion, a silver chlorobromide emulsion, etc. The silver halide emulsion used in this invention is mainly a gelatino silver halide emulsion but the emulsion may contain, besides gelatin, polyvinyl alcohol, an alginic acid polymer, polyvinyl imidazole, polyvinyl pyrrolidone, or copolymers thereof, or may be an emulsion thereof.

The silver halide emulsion of this invention is applied to a suitable support according to the desired use, such as a paper, a glass plate, a cellulose triacetate film, a polyethylene terephthalate film, other plastic films than above, a baryta-coated paper, a resin-coated paper, or a synthetic paper.

The present invention will be illustrated further by the following examples which are merely illustrative and not limited in nature.

EXAMPLE 1 50 g of l-pheny1-3-[3-(2,4-di-tertiaryamylphenoxyactamido)-benzamido]S-pyrazolone was dissolved in 100 ml of dibutyl phthalate by heating and the resultant solution was added to 1 liter of a 10 percent aqueous gelatin solution. Then, 50 ml of a 5 percent aqueous solution of sodium alkylbenzene sulfonate was added thereto and they were dispersed by emulsification by means of a high speed rotary mixer (the product is called the dispersion of the magenta coupler).

1 kg. of a silver iodobromide emulsion (containing 0.25 mol of silver and 4.0 mol percent of iodine) prepared by a conventional method was placed in a beaker and melted at 40C. After adding to the emulsion the sensitizing dye in the amounts shown in Table 1, the emulsion was stirred for minutes. Further, 400 g. of the dispersion of the magenta coupler as prepared above was added to the emulsion with stirring and after adding further suitable amounts of a hardening agent and an ampholite surface active agent as a wetting agent to the mixture with stirring, the resultant mixture was applied to a cellulose triacetate film in a thickness of 7 microns to obtain a sample of a green-sensitive light-sensitive material.

The sample was cut into strips and subjected to an optical wedge exposure through Yellow Filter No. K-12 made by Fuji Photo Film Co. by using a sensitometer of 5400K in color temperature of the light source. The strip thus exposed was developed for 12 minutes at C in a color developer having the following composition:

N,N-diethy1-p-aminoaniline sulfate 2.0 g Sodium sulfite 2.0 g Sodium carbonate monohydrate 50.0 g Hydroxylamine hydrochloride 1.5 g Potassium bromide 1.0 g Water to make 1000 ml Thereafter, the strip was further processed in a first fixing solution, a bleaching solution and a second fixing solution and washed with water to obtain a magenta image. After drying the sample strips thus processed, the green filter density was measured by using an S- type Densitometer made by Fuji Photo Film Co., from which characteristic curves were obtained. From these results, the densities at the point of fog plus 0.20 were calculated and the results are shown in Table 1.

The compositions of the bleaching solution and the fixing solution used in the above processing were as follows:

Composition of the Bleaching Solution Ferricyanide 100 3 Potassium bromide 20 g Water to make 1000 ml (pH, 6.9 i 0.3)

Composition of the Fixing Solution yp 200 g Sodium sulfite 20 g Acetic acid (28%) 45 ml Boric acid 7.5 g Potassium alum 20 g Water to make 1000 ml TABLE 1 Dye Amount (ml) Dye Amount (ml) (A) (B) (mol concent- (mol concentration) ration) (1A) 40(5X10") 115 0.17 120 0.23 40 (11C) 20(1X10') 142 0.18 40 165 0.20 120 158 0.23 40 43 0.11 120 50 0.12 (TB) 40(5X10") 0.13 80 100 0.15 40 (11A) 40(1Xl0") 200 0.25 80 186 0.25 40 35 0.13 80 35 0.13 40 (11B) 40(1X10") 220 0.21 80 282 0.25 4O 43 0.13 80 46 0.13 40 (11D) 40(1X10") 190 0.23 80 220 0.25 40 33 0.1 1 80 35 0.12 (1C) 40(5X10) 0.13 80 105 0.15 40 (11E) 40(5X10) 200 0.19 80 220 0.20 160 220 0.22 40 45 0.18 80 50 0.17 160 58 0.15 40 (11F)20(1Xl0") 252 0.24 40 282 0.27 80 218 0.26 20 50 0.22 40 60 0.22 80 60 0.22 (15) 40(5X10") 0.18 80 0.24 40 40( 1X 10) 200 0.20 80 234 0.21 40 25 0.17 80 25 0.19 (1D) 40(1X10") 118 0.18 80 1 18 0.14 40 (111-1) 40(5X10") 250 0.17 80 316 0.20 40 33 0.15 80 40 0.15 (1 4 l0") 100 0.15

80 115 0.22 40 ("8) 40(1Xl0") 200 0.20 80 220 0.25 (1F) 40 79 0.25 80 85 0.27 40 (NC) 20(1X10") 118 0.27 40 150 0.30

(A): Relative yellow filter sensitivity (SY) (B): Fog.

EXAMPLE 2 As in Example 1, 1 kg of a silver iodobromide emulsion (containing 0.30 mol of silver and 6.0 mol% of iodine) was melted in a beaker at 40C and the amounts of the sensitizing dyes l and II and the compound of formula III shown in Table 2 were added to the emulsion with stirring. -7 ml of the silver halide emulsion thus obtained was applied to a glass plate of cabinet size followed by drying to obtain a sample.

The sample was cut into strips and the strips were subjected to an optical wedge exposure by yellow light as in Example 1 and then developed in a developer having the following composition for 10 minutes at C.

Composition of the Developer Water 500 ml Metol 0.3 g Sodium pyrosulfite 38 g Hydroquinone 6 g Sodium carbonate monohydrate 22.5 g Citric acid 0.7 g Potassium bromide 0.9 g Water to make 1000 ml The strips were then fixed and the optical densities thereof were measured, the results of which are shown in Table 2.

TABLE 2 Dye Amount(ml) Dye Amount(ml) Compd Amt (ml) A B (mol concen- (mol concen- (mol concentration) tration) tration) lB 40(5X10") 100 0.15 80 97 0.16 40 lIB40(1 10) 142 0.15 t. .t 80 178 016 60 111A 20(1X10'-) 166 0.15 t. 40 t. 20 0'15 n 80 200 (M6 HIB 40(lX10") I78 0.16 u u 80 I90 046 lllC 40(1Xl0') 190 0.16 u so 200 017 (A): Relative yellow filter sensitivity (Sy) (B): Fog

What is claimed is:

l. A super-sensitized silver halide photographic emulsion containing at least one sensitizing dye represented by the following first formula:

. I R 1 l substituent being alkyl, halogen, trifluoroalkyl, cyano, alkyl-sulfonyl, alkylsulfomyl or alkylcarbamyl; and at least one sensitizing dye represented by the following second formula:

wherein R is alkyl or sulfoalkyl; R is alkyl, sulfoalkyl, sulfoalkoxyalkoxy or sulfoalkylcarbamylalkyl; Z represents a non-metallic atomic group necessary to complete a Z-quinoline substituted or unsubstituted heterocyclic nucleus, the substituent being alkyl or halogen; and Z represents a non-metallic group necessary to complete a substituted or unsubstituted heterocyclic nucleus selected from the group consisting of benzoxazole, naphthoxazole, benzthiazole, benzselenazole, naphthothiazole or naphthoselenazole, the substituent being halogen or sulfoalkoxy; with the proviso that when Z contains a sulfoalkoxy group, R and R is alkyl.

2. A super-sensitized silver halide emulsion according to claim 1 wherein said silver halide emulsion further contains a compound represented by the following formula III:

FORMULA III wherein R represents an alkyl group or a substituted alkyl group wherein the substituent is a sulfo group neutralized by a cation, a cyano group or a vinyl group; Z represents an atomic group necessary to complete a heterocyclic nucleus of the benzimidazole series; and Z represents a phenyl group or a substituted phenyl group wherein the substituent is alkyl or alkoxy.

3. A silver halide emulsion according to claim 1 wherein'the alkyl group of R to R is methyl, ethyl, npropyl, iso-propyl, n-butyl or iso-butyl.

4. A silver halide emulsion according to claim 2 wherein the alkyl group of R to R is methyl, ethyl, npropyl, iso-propyl, n-butyl or iso-butyl.

5. A silver halide emulsion according to claim 1 wherein said substituted alkyl group is a vinylmethyl group, a benzyl group, a B-acetoxyethyl group, a 'yacetoxypropyl group, a y-carboxypropyl group, a B- carboxyethyl group, a y-sulfatopropyl group, a 8- sulfatobutyl group, a S-N-acetylsulfamylbutyl group, a B-hydroxyethyl group, a y-sulfopropyl group, a 'y-sulfobutyl group, a 8-sulfobutyl group, a 2-(3-sulfopropoxy)ethyl group, a 2[2-(3-sulfopropoxy)ethoxylethyl group, or a 2-hydroxy-l-sulfopropyl group.

6. A silver halide emulsion according to claim 1 wherein the heterocyclic nucleus of the benzimidazole series completed by Z Z or Z, is a benzimidazole nucleus, or a benzimidazole nucleus containing, as a component of the skeletal-structure thereof, a benzene ring substituted by at least one of the groups consisting of a halogen atom, an N-unsubstituted or alkyl substituted sulfamyl or carbamyl group, an N-disubstituted sulfamyl group, an alkyl sulfonyl group, a trifluoromethyl group, an alkyl group, a cyano group, a

phenyl group, a carboalkoxyl group, a hydroxyl group 1m and an alkoxyl group. I

7. A silver halide emulsion according to claim 1 Clwherein the heterocyclic nucleus of the 2-quinoline series is a 2-quinoline nucleus or a 2-quinoline nucleus 5 containing, as a component of the skeletal-structure thereof, a benzene ring substituted by at least one of 11915011 the groups consisting of an alkyl group and a halogen (31W atom. N

8. A silver halide emulsion as in claim 1 wherein the -01 light-sensitivity in the wave length region of 500-530 mu is increased. C

9. A silver halide emulsion as in claim 2 wherein the N total amount of said sensitizing dyes I and II and said (0119180? compound of formula III is within the range of from 1 X 10' mol to l X 10* mol per mol of Silver halide- 14. A silver halide emulsion as in claim 1 which con- 10. A silver halide emulsion as in claim 1 wherein wins the sensitizing dye of the following formula; said emulsion contains the following sensitizing dyes:

CJII5 I? (cnmsw (Jammie o 0,11,50,-

11. A silver halide emulsion as in claim 1 wherein at least one sensitizing dye of formula II and at least one said emulsion contains one sensitizing dye of formula I compound of formula III.

and asensitizing dye of the following formula: 15: A silver halide emulsion according to claim 14 (1113) H C 3 wherein said emulsion contains the following sensitiz- 3 a ing dyes:

\ CH:C

f 4 can N wherein said sensitizing dye of formula I is:

( 2115 C 2H5 4 C 2 5 0 l (IIB) cllrlNncocamsoa mc- 12. A silver halide emulsion according to claim 11 \V *CHZC CzHrNHC OCaHaSOa' and a compound of the following formula:

IIIA) 0:1

13. A silver halide emulsion according to claim 11 I I wherein said sensitizing dye of formula I is 0,115

16. A silver halide emulsion as in claim 1 wherein (10) said emulsion contains the following sensitizing dyes: (Inns UHZJHL mm (CH2CH2O)2SOF v (IA) 02115 0211 20. A silver halide emulsion as in claim 1 wherein 01 N said emulsion contains the following sensitizin d es:

N\ 01 g Y ZM F 2 5 (01193501- 17 A silver halide emulsion as in claim 1 wherein CZHS said emulsion contains the following sensitizing dyes: ID) (IE) CzIIr, C2H5 l S e 20 18. A silver halide emulsion as in claim 1 wherein 21. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes: said emulsion contains the following sensitizing dyes:

wmnsor 5 C2115 ?HzCH=OHz Cl N N o wnmsor 01115 on 19. A silver halide emulsion as in claim 1 wherein E i said emulsion contains the following sensitizing dyes: 1193503 (I F) q 22. A photographic light-sensitive element compris- -c1r=c ing a support having thereon at least one layer contain- N ing the photographic silver halide emulsion as in claim can N 2m 1.

H3 It =0 0

Claims

2. A super-sensitized silver halide emulsion according to claim 1 wherein said silver halide emulsion further contains a compound represented by the following formula III:
3. A silver halide emulsion according to claim 1 wherein the alkyl group of R1 to R6 is methyl, ethyl, n-propyl, iso-propyl, n-butyl or iso-butyl.
4. A silver halide emulsion according to claim 2 wherein the alkyl group of R1 to R7 is methyl, ethyl, n-propyl, iso-propyl, n-butyl or iso-butyl.
5. A silver halide emulsion according to claim 1 wherein said substituted alkyl group is a vinylmethyl group, a benzyl group, a Beta -acetoxyethyl group, a gamma -acetoxypropyl group, a gamma -carboxypropyl group, a Beta -carboxyethyl group, a gamma -sulfatopropyl group, a delta -sulfatobutyl group, a delta -N-acetylsulfamylbutyl group, a Beta -hydroxyethyl group, a gamma -sulfopropyl group, a gamma -sulfobutyl group, a delta -sulfobutyl group, a 2-(3-sulfopropoxy)ethyl group, a 2(2-(3-sulfopropoxy)ethoxy)ethyl group, or a 2-hydroxy-1-sulfopropyl group.
6. A silver halide emulsion according to claim 1 wherein the heterocyclic nucleus of the benzimidazole series completed by Z1, Z2 or Z5 is a benzimidazole nucleus, or a benzimidazole nucleus containing, as a component of the skeletal-structure thereof, a benzene ring substituted by at least one of the groups consisting of a halogen atom, an N-unsubstituted or alkyl substituted sulfamyl or carbamyl group, an N-disubstituted sulfamyl group, an alkyl sulfonyl group, a trifluoromethyl group, an alkyl group, a cyano group, a phenyl group, a carboalkoxyl group, a hydroxyl group and an alkoxyl group.
7. A silver halide emulsion according to claim 1 wherein the heterocyclic nucleus of the 2-quinoline series is a 2-quinoline nucleus or a 2-quinoline nucleus containing, as a component of the skeletal-structure thereof, a benzene ring substituted by at least one of the groups consisting of an alkyl group and a Halogen atom.
8. A silver halide emulsion as in claim 1 wherein the light-sensitivity in the wave length region of 500-530 m Mu is increased.
9. A silver halide emulsion as in claim 2 wherein the total amount of said sensitizing dyes I and II and said compound of formula III is within the range of from 1 X 10 6 mol to 1 X 10 3 mol per mol of silver halide.
10. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
11. A silver halide emulsion as in claim 1 wherein said emulsion contains one sensitizing dye of formula I and a sensitizing dye of the following formula:
12. A silver halide emulsion according to claim 11 wherein said sensitizing dye of formula I is:
13. A silver halide emulsion according to claim 11 wherein said sensitizing dye of formula I is
14. A silver halide emulsion as in claim 1 which contains the sensitizing dye of the following formula:
15. A silver halide emulsion according to claim 14 wherein said emulsion contains the following sensitizing dyes:
16. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
17. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
18. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
19. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
20. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
21. A silver halide emulsion as in claim 1 wherein said emulsion contains the following sensitizing dyes:
22. A photographic light-sensitive element comprising a support having thereon at least one layer containing the photographic silver halide emulsion as in claim 1.