Supersensitization of red sensitized, silver halide emulsions with 5-substituted-amino-1,2,3,4-thiatriazoles

Abstract

5-Substituted-amino-1,2,3,4-thiatriazoles have been found to be supersensitizers for silver halide photographic emulsions spectrally sensitized to the red region of the electromagnetic spectrum.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the use of supersensitizers in photographic emulsions.

2. Background of the Art

In most uses of silver halide in photographic materials, it is desirable to increase the speed or sensitivity of the emulsion. There are a number of different techniques for increasing the speed of an emulsion which are usually classified as chemical sensitization or spectral sensitization. Chemical sensitization usually involves modification of the silver halide grains to make the most efficient use of the radiation that they absorb. The three general types of chemical sensitization are sulfur sensitization, reduction sensitization, and precious (noble) metal sensitization. These methods of chemical sensitization are well known and firmly established in the art (e.g., James, T. H. and Vanselow, W. "Chemical Sensitization", J. Photo. Sci., 1, 133 (1953), Freiser, H. and Ranz, E., Ber der Bunsengesellschaft, 68, 389 (1964), and Pouradier, J. "Chemical Sensitization", Photographic Theory: Liege Summer School, A. Hautot, p. 111, Focal Press (London 1963).

Spectral sensitization enables grains to benefit from radiation in regions of the electromagnetic spectrum where the silver halide would ordinarily not absorb. Dyes which absorb radiation and can transfer energy to the grains to help in the photoreduction of silver ions to clusters of silver metal are conventionally used to effect spectral sensitization.

Another phenomenon associated with the use of spectral sensitizing dyes is known in the art as supersensitization. The addition of other substances, frequently in quantities ranging from an equivalent molar rate to a 100 fold molar excess of supersensitizer to dye, can increase the spectrally sensitized speed of the emulsion by more than an order of magnitude. Some supersensitizers are dyes themselves, but many others do not absorb radiation in significant amounts in the visible portion of the electromagnetic spectrum. Therefore, the effect of supersensitizers on spectral sensitization is not clearly dependent on the ability of compounds to absorb radiation in the visible portion of the spectrum. Certain cyanines, merocyanine compounds analogous to cyanines, certain acylmethylene derivatives of heterocyclic bases, and ketone derivatives such as p-dimethylaminobenzalacetone are known supersensitizers. An expanded selection of supersensitizers is therefore desired.

Mercaptotetrazoles are generally taught in U.S. Pat. Nos. 2,403,977; 3,266,897; and 3,397,987.

U.S. Pat. No. 2,875,058 describes the use of triazines such as Leucophor BCF to supersensitize infrared sensitized silver halide emulsions.

U.S. Pat. No. 4,030,927 and 4,105,454 describe red and infrared sensitive emulsions which are supersensitized by halogen substituted benzotriazoles and benzotriazole compounds, respectively.

U.S. Pat. No. 3,592,656 describes the super-sensitization of merocyanine dye sensitized silver halide emulsions with heterocyclic compounds selected from pyrazoles, 5-pyrazolones, 3-pyrazolones, 3,5-pyrazolidenediones, triazoles, tetrazoles, xanthines, imidazoles, imidazolidines, and imidiazolinium salts.

U.S. Pat. No. 3,457,078 describes the use of mercapto substituted oxazine, oxazole, thiazole, thiadiazole, imidazole or tetrazole as supersensitizers in combination with certain cyanine dyes.

U.S. patent application No. 59,932 describes the use of 5-substituted-amino-1,2,3,4-thiatriazoles as infrared supersensitizers to wavelengths above 750 nm.

SUMMARY OF THE INVENTION

Silver halide emulsions which have been spectrally sensitized to the red region (590 up to but not above 750 nm) of the electromagnetic spectrum are supersensitized by the addition of 5-substituted-amino-1,2,3,4-thiatriazoles.

DETAILED DESCRIPTION OF THE INVENTION

Silver halide crystals have an inherent photosensitivity only in the ultraviolet and blue regions of the electromagnetic spectrum. In order to provide the crystals with sensitivity to other portions of the electromagnetic spectrum, dyes are used. These dyes which extend the range of sensitivity of the silver halide are generally referred to as spectral sensitizing dyes. As noted above, supersensitizers increase the efficiency of these spectral sensitizing dyes.

Traditionally, emulsions which have been spectrally sensitized to the red region of the spectrum have been sensitized inefficiently. The relative sensitivities of red sensitized emulsions tend to be lower than the relative sensitivities of emulsions spectrally sensitized to the green and blue regions of the spectrum. The need for supersensitizers in the red (590 to 750 nm) is therefore considered to be generally very important.

It has been found in the present invention that 5-substituted-amino-1,2,3,4-thiatriazoles wherein the 5-substituent is connected through an amine linking group are effective supersensitizers for silver halide emulsions spectrally sensitized to wavelengths between 590 and 750 nm. Preferably the amine linking group is a secondary amine (i.e.,--NH--). More preferably the supersensitizers of the present invention are represented by the structural formula ##STR1## wherein R is selected from the group consisting of alkyl (preferably of 1 to 12 carbon atoms, more preferably of 1 to 4 carbon atoms), aryl (preferably phenyl and substituted phenyl, more preferably p-substituted phenyl, with examples of preferred substituents being selected from the class consisting of halogen (e.g. Br and Cl), hydroxyl, alkyl (e.g. of 1 to 12 carbon atoms, preferably 1 to 4 carbon atoms), alkoxy (e.g. of 1 to 12 carbon atoms, preferably of 1 to 4 carbon atoms), fused aromatic rings (to form naphthyl groups or substituted naphthyl groups with substituents preferred similar to those used with R equals substituted aryl)), allyl, and 5- or 6-membered heterocyclic rings composed of C, S, N, and O atom.

Examples of compounds of the present invention include, but are not limited to, the following:

ATT; 5-anilino-1,2,3,4-thiatriazole NATT; 5-(1-naphthylamino)-1,2,3,4-thiatriazole EATT; 5-(N-ethylamino)-1,2,3,4-thiatriazole AATT; 5-allylamino-1,2,3,4-thiatriazole ClATT; 5-(4-chloroanilino)-1,2,3,4-thiatriazole PMATT; 5-(4-methoxyanilino)-1,2,3,4-thiatriazole MATT; 5-(N-methylamino)-1,2,3,4-thiatriazole BATT; 5-(4-bromoanilino)-1,2,3,4-thiatriazole HATT; 5-(4-hydroxyanilino)-1,2,3,4-thiatriazole CNATT; 5-(4-cyanoanilino)-1,2,3,4-thiatriazole.

These type of compounds are added to the optically sensitized emulsions in any of the conventional methods by which supersensitizers or other adjuvants are added to photographic emulsions. Typically the supersensitizing compounds of the present invention are added into the emulsion mixture just prior to coating, mixed well, then coated onto the photographic substrate. The compounds are added as aqueous solutions, aqueous dispersions, or organic solvent solutions (e.g., methanol) alone, or with other desirable adjuvants.

The compounds of the present invention may be added in any effective supersensitizing amount to the photographic emulsion. The concentration of ingredients and materials can vary significantly in photographic emulsions such as from 0.5 to 10 g/m.sup.2 for silver. The supersensitizers may also vary significantly in concentration. A generally useful range would be from 0.001 to 1.0 percent by dry weight of the supersensitizer to the total silver halide emulsion layer. This would generally comprise about 0.01 to 10% by weight of the silver halide in the photographic emulsion layer. A more preferred range would be from 0.1 to 5% for the total supersensitizer combination by weight of the silver halide or about 0.01 to 0.5% total dry weight of the coated emulsion layer.

Any red spectral sensitizing dye may be used in the practice of the present invention with the supersensitizing compounds of the present invention. Useful dyes for this purpose tend to be merocyanines, cyanines and dicarbocyanines.

The preferred class of dye according to the present invention is represented by the following general formula (I): ##STR2## wherein:

R.sup.0 and R.sup.1 can be a substituted alkyl group or a non-substituted alkyl having from 1 to 8 carbon atoms such as, for example, methyl, ethyl, propyl, butyl, amyl, benzyl, octyl, carboxymethyl, carboxyethyl, sulfopropyl, carboxypropyl, carboxybutyl, sulfoethyl, sulfoisopropyl and sulfobutyl groups;

X.sup.- is any acid anion such as, for example, chloride, bromide, iodide, perchlorate, sulfamate, thiocyanate, p-toluenesulfonate and benzenesulfonate;

Z.sup.0 and Z.sup.1 are independently the non-metallic atoms necessary to complete an aromatic heterocyclic nucleus chosen within those of the thiazole series, benzothiazole series, [1,2-d]-naphthothiazole series, [2,1-d]-naphthothiazole series, oxazole series, benzoxazole series, selenazole series, benzoselenazole series, [1,2-d]-naphthoselenazole series, [2,1-d]-naphthoselenazole series, thiazoline series, 4-quinoline series, 2-pyridine series, 4-pyridine series, 3,3-dialkyl-indolenine series (wherein alkyl has a meaning known to those skilled in the art including alkyl groups having 1 to 12 carbon atoms), imidazole series and benzimidazole series.

R.sup.2, R.sup.3 and R.sup.4 each represent a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, an alkyl group, an unsubstituted or substituted aryl group or an acyloxy group. R.sup.2 and R.sup.3 can also be combined to represent a ring system such as an isopherone, cyclohexane, etc.

l, m, n and p are 0 or 1.

The emulsion is preferably sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consisting of thiazoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles [1,2-d]-naphthoselenazoles, [2,1-d]naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.

Silver halide emulsions supersensitized in accordance with this invention can comprise silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, silver chlorobromoiodide or mixtures thereof. Such emulsions can be coarse, medium or fine grain (or mixtures thereof) and can be prepared by any of the well-known procedures, e.g., single jet emulsions or double jet emulsions. Useful emulsions include Lippmann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions such as those described in Nietz et al., U.S. Pat. No. 2,222,264, Illingsworth, U.S. Pat. No. 3,320,069, and McBride, U.S. Pat. No. 3,271,157; or cubic grain emulsions, such as those described by Kline and Moisar, Journal of Photographic Science, volume 12, page 242 et seq. or markocki, The Spectral Sensitization of Silver Bromide Emulsions on Different Crystallographic Faces, Journal of Photographic Science, Volume 13, 1965; or Illingsworth, British Pat. No. 1,156,193 published Jun. 25, 1969.

Tabular or lamellar grain emulsions as described in U.S. Pat. Nos. 4,425,425, 4,439,520 and 4,425,426 are also equally useful.

The silver halide emulsions supersensitized with the compounds of this invention can be unwashed or washed to remove soluble salts. In the latter case the soluble salts can be removed by chill-setting and leeching or the emulsion can be coagulation washed e.g., by the procedures described in Hewitson et al., U.S. Pat. No. 2,618,556; Yutzy et al., U.S. Pat. No. 2,614,928; Yackel, U.S. Pat. No. 2,565,418; Hart et al., U.S. Pat. No. 3,241,969; and Waller et al., U.S. Pat. No. 2,489,341.

Photographic emulsions containing supersensitizing combinations in accordance with this invention can be sensitized with chemical sensitizers, such as with reducing agents; sulfur, selenium or tellurium compounds; gold, platinum or palladium compounds; or combinations of these. Suitable chemical sensitization procedures are described in Shepard, U.S. Pat. No. 1,623,499; Waller, U.S. Pat. No. 2,399,083; McVeigh, U.S. Pat. No. 3,297,447; and Dunn, U.S. Pat. No. 3,297,446.

The supersensitized silver halide emulsions of this invention can contain speed increasing compounds such as polyalkylene glycols, cationic surface active agents and thioethers or combinations of these as described in Piper, U.S. Pat. No. 2,886,437; Chechak, U.S. Pat. No. 3,046,134; Carroll et al., U.S. Pat. No. 2,944,900; and Goffe, U.S. Pat. No. 3,294,540.

Silver halide emulsions containing the supersensitizing combinations of this invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers which can be used alone or in combination, include the thiazolium salts described in Staud, U.S. Pat. No. 2,131,038 and Allen, U.S. Pat. No. 2,694,716; the azaindenes described in Piper, U.S. Pat. No. 2,886,437 and Heimbach, U.S. Pat. No. 2,444,605; the mercury salts described in Allen, U.S. Patent No. 2,728,663; the urazoles described in Anderson, U.S. Pat. No. 3,287,135; the sulfocatechols described in Kennard, U.S. Pat. No. 3,235,652; the oximes described in Carroll et al., British Patent No. 623,448; nitron; nitroindazoles, the polyvalent metal salts described in Jones, U.S. Pat. No. 2,839,405; the thiuronium salts described in Herz, U.S. Pat. No. 3,220,839; and the palladium, platinum and gold salts described in Trivelli, U.S. Pat. No. 2,566,263 and Damschroder, U.S. Pat. No. 2,597,915.

Photographic elements including emulsions supersensitized in accordance with this invention can contain incorporated developing agents such as hydroquinones, catechols, aminophenols, 3-pyrazolidones, ascorbic acid and its derivatives, reductones and phenylenediamines, or combinations of developing agents. The developing agents can be in the silver halide emulsion and/or in another suitable location in the photographic element. The developing agents can be added from suitable solvents or in the form of dispersions as described in Yackel, U.S. Pat. No. 2,592,368 and Dunn et al., French Patent No. 1,505,778.

Silver halide supersensitized in accordance with the invention can be dispersed in colloids that can be hardened by various organic or inorganic hardeners, alone or in combination, such as the aldehydes, blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfones, active halogen compounds, epoxy compounds, aziridines, active olefins, isocyanates, carbodiimides, mixed function hardeners and polymeric hardeners such as oxidized polysaccharides, e.g., dialdehyde starch, oxyguargum, etc.

Photographic emulsions supersensitized with the materials described herein can contain various colloids alone or in combination as vehicles or binding agents. Suitable hydrophilic materials include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives (e.g., phthalated gelatin), cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water soluble polyvinyl compounds, e.g., poly(vinylpyrrolidone) acrylamide polymers or other synthetic polymeric compounds such as dispersed vinyl compounds in latex form, and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described, for example, in U.S. Pat. Nos. 3,142,568 of Nottorf; 3,193,386 of white; 3,062,674 or Houck, Smith and Yudelson; 3,220,844 of Houck, Smith and Yudelson; Ream and Fowler, 3,287,289; and Dykstra, U.S. Pat. No. 3,411,911; particularly effective are those water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, those which have cross linking sites which facilitate hardening or curing and those having recurring sulfobetaine units as described in Canadian Patent No. 774,054.

Emulsions supersensitized in accordance with this invention can be used in photographic elements which contain antistatic or conducting layers, such as layers that comprise soluble salts, e.g., chlorides, nitrates, etc., evaporated metal layers, ionic polymers such as those described in Minsk, U.S. Pat. Nos. 2,861,056 and 3,206,312 or insoluble inorganic salts such as those described in Trevoy, U.S. Pat. No. 3,428,451.

Photographic emulsions containing the supersensitizing combinations of the invention can be coated on a wide variety of supports. Typical supports include polyester film, subbed polyester film, poly(ethylene terephthalate) film, cellulose nitrate film, cellulose ester film, poly(vinyl acetal) film, polycarbonate film and related films or resinous materials, as well as glass, paper, metal and the like. Typically, a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/or an alpha-olefin polymer, particularly a polymer of an alpha-olefin containing 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylenebutene copolymers and the like.

Supersensitized emulsions of the invention can contain plasticizers and lubricants such as polyalcohols, e.g., glycerin and diols of the type described in Milton, U.S. Pat. No. 2,960,404; fatty acids or esters such as those described in Robijns, U.S. Pat. No. 2,588,765 and Duane, U.S. Pat. No. 3,121,060; and silicone resins such as those described in DuPont British Patent No. 955,061.

The photographic emulsions supersensitized as described herein can contain surfactants such as saponin, anionic compounds, such as the alkylarylsulfonates described in Baldsiefen, U.S. Pat. No. 2,600,831 fluorinated surfactants, and amphoteric compounds such as those described in Ben-Ezra, U.S. Pat. No. 3,133,816.

Photographic elements containing emulsion layers sensitized as described herein can contain matting agents such as starch, titanium dioxide, zinc oxide, silica, polymeric beads including beads of the type described in Jelley et al., U.S. Pat. No. 2,992,101 and Lynn, U.S. Pat. No. 2,701,245.

Spectrally sensitized emulsions of the invention can be utilized in photographic elements which contain brightening agents including stilbene, triazine, oxazole and coumarin brightening agents. Water soluble brightening agents can be used such as those described in Albers et al., German Patent No. 972,067 and McFall et al., U.S. Patent No. 2,933,390 or dispersions of brighteners can be used such as those described in Jansen, German Pat. No. 1,150,274 and Oetiker et al., U.S. Pat. No. 3,406,070.

Photographic elements containing emulsion layers supersensitized according to the present invention can be used in photographic elements which contain light absorbing materials and filter dyes such as those described in Sawdey, U.S. Pat. No. 3,253,921; Gaspar, U.S. Pat. No. 2,274,782; Carroll et al., U.S. Pat. No. 2,527,583 and Van Campen, U.S. Pat. No. 2,956,879. If desired, the dyes can be mordanted, for example, as described in Milton and Jones, U.S. Pat. No. 3,282,699.

The sensitizing dyes and/or supersensitizers (and other emulsion addenda) can be added to the photographic emulsions from water solutions or suitable organic solvent solutions, for example with the procedure described in Collins et al., U.S. Pat. No. 2,912,343; Owens et al., U.S. Pat. No. 3,342,605; Audran, U.S. Pat. No. 2,996,287 or Johnson et al., U.S. Pat. No. 3,425,835. The dyes can be dissolved separately or together, and the separate or combined solutions can be added to a silver halide emulsion, or a silver halide emulsion layer can be bathed in the solution of supersensitizers and/or dyes.

Contrast enhancing additives such as hydrazines, rhodium, iridium and combinations thereof are also useful.

Photographic emulsions of this invention can be coated by various coating procedures including dip coating, air knife coating, curtain coating, or extrusion coating using hoppers of the type described in Beguin, U.S. Pat. No. 2,681,294. If desired, two or more layers may be coated simultaneously by the procedures described in Russell, U.S. Pat. Nos. 2,761,791 and Wynn, British Patent No. 837,095.

Silver halide emulsions containing the supersensitizer combinations of this invention can be used in elements designed for color photography, for example, elements containing color-forming couplers such as those described in Frolich et al., U.S. Pat. No. 2,376,679; Vittum et al., U.S. Pat. No. 2,322,027; Fierke et al., U.S. Pat. No. 2,801,171; Godowsky, U.S. Pat. No. 2,698,794; Barr et al., U.S. Pat. No. 3,227,554 and Graham, U.S. Pat. No. 3,046,129; or elements to be developed in solutions containing color-forming couplers such a those described in Mannes and Godowsky, U.S. Pat. No. 2,252,718; Carroll et al. U.S. Pat. No. 2,592,243 and Schwan, U.S. Pat. No. 2,950,970.

Exposed photographic emulsions of this invention can be processed by various methods including processing in alkaline solutions containing conventional developing agents such as hydroquinones, catechols, aminophenols, 3-pyrazolidones, phenylenediamines, ascorbic acid derivatives, hydroxylamines, hydrazines and the like; web processing such as described in Tegillus et al., U.S. Pat. No. 3,179,517; stabilization processing as described in Yackel et al. "Stabilization Processing of Films and Papers", PSA Journal, vol. 16B, August 1950; monobath processing as described in Levy "Combined Development and Fixation of Photographic Images with Monobaths", Phot. Sci. and Eng., Vol. 2, No. 3, October 1958, and Barnes et al., U.S. Pat. No. 3,392,019. If desired, the photographic emulsions of this invention can be processed in hardening developers such as those described in Allen et al., U.S. Pat. No. 3,232,761; in a roller transport processor such as those described in Russell, U.S. Pat. No. 3,025,779; or by surface application processing as described in Example 3, of Kitze, U.S. Pat. No. 3,418,132.

The following is the description of a general synthetic procedure which may be used in the preparation of any 5-substituted-amino-1,2,3,4-thiatriazole.

Preparation of Aryl Thiosemicarbazides

To a cooled and stirred ethanolic solution of the primary aromatic amine (0.25 mole) having the selected R group was slowly added 40 mls of ammonium hydroxide (sp. gr. 0.90). With the temperature maintained below 20.degree. C., carbon disulfide (15 mls) was added over a 15 minute period. After one hour, an aqueous solution of the sodium salt of monochloroacetic acid (0.25 mole) was added to this mixture followed by addition of hydrazine hydrate (0.25 mole). The mixture was cooled overnight in a refrigerator. The crude thiosemicarbazide was filtered out and recrystallized from ethanol and water.

Preparation of 5-Amino Substituted 1,2,3,4-Thiatriazole

To a cooled and stirred mixture of the thiosemicarbazide (0.10 mole) generated in the above procedure and hydrochloric acid (76.0 ml, 15%) was added sodium nitrite (0.10 mole, 6.90 grams) in 50 mls of water over a period of 30 minutes. The solid material which formed was filtered and recrystallized from ethanol. Melting points, where available, were in agreement with values reported in the literature. NMR and IR spectral data correlated with the appropriate structures.

These and other aspects of the invention will be shown by the Examples.

Two different emulsions were used in the various examples to show the practice of the present invention. Emulsion A was prepared by a double jet precipitation to provide an emulsion with 64% chloride and 36% bromide with an average grain size of 0.24 micrometers. The emulsion was digested with p-toluenesulfinic acid, sodium thiosulfate and sodium gold tetrachloride (NaAuCl.sub.4).

Emulsion B was an ammoniacal iodobromide emulsion made by double jet precipitation with all potassium iodide and ammonia in the kettle before precipitation. The resulting emulsion was 3% iodide and 97% bromide with an average grain size of 0.24 micrometers. The emulsion was then chemically digested with sulfur and gold.

Final preparation of the emulsions comprised the addition of water and gelatin to a level of 5.0% gelatin and 2500 g of emulsion per mole of silver. The pH was adjusted to 7.0, and the pAg was adjusted to 7.2. Red sensitizing dyes (D1-D3) and the amino thiatriazoles were added as 0.1% solutions in methanol. All additives listed in the tables are given in quantities per mole of silver. Formaldehyde hardener and surfactant were added before coating as aqueous solutions. The coatings were run at 2.4g Ag/m.sup.2 on 7 mil (0.178 mm) clear polyester base. ##STR3##

EXAMPLES 1-3

The supersensitizing effects were investigated with emulsion A (sulfur and gold disgested chlorobromide emulsion) and the red sensitizing dyes D1 and D2. The level for both dyes, D1 and D2, was 100 mg/mole Ag. A wedge spectra was run of each to determine the peak sensitivity of each dye. The peak sensitivities were 660 nm for D1 and 700 nm for D2. The dye, D1, had high sensitivity at 633 nm and was also examined at that wavelength. The films were then evaluated on a sensitometer with a 10.sup.-3 second exposure through narrow band filters matching the peak sensitivity of each dye and also at 633 nm for D1. The exposed films were developed in a 90 second x-ray processor. Sensitometric results are given for film aged one day at room temperature (fresh) and incubated at 50.degree. C. and 60% RH for one week (incubated). The sensitometric results include Dmin, Speed, (percent change in speed for emulsion without additives) and average contrast (CONT). The results are listed in Table 1 for the amino thiatriazole, ClATT. The addition of ClATT not only increased the speed of the red sensitizing dyes but also acted as an antifoggant reducing both fresh and incubated Dmin.

TABLE I__________________________________________________________________________ NarrowClATT Band(mg/ Filter FRESH INCUBATEDEx. Dye mole) (nm) Dmin SPD CONT Dmin SPD CONT__________________________________________________________________________A D1 -- 633 0.049 100 2.63 0.061 83 2.561 D1 150 633 0.046 162 2.88 0.049 138 2.75B D1 -- 660 0.049 100 2.68 0.058 83 2.502 D1 150 660 0.045 178 2.86 0.050 144 2.71C D2 -- 700 0.048 100 2.69 0.062 76 2.553 D2 150 700 0.041 148 2.67 0.044 120 2.58__________________________________________________________________________

EXAMPLES 4-23

The procedure outlined in examples 1-3 was repeated to evaluate additional amino thiatriazoles. The chlorobromide emulsion (A) was dyed with 75 mg/mole Ag of D1. The sensitometric results are listed in Table 2 and were obtained with a 660 nm narrow band filter. The data show strong supersensitization of red dye, D1, with all the amino thiatrizoles tested.

TABLE II______________________________________Thiatriazoles FRESHEX. (mg/mole) Dmin SPD CONT______________________________________D -- 0.050 100 2.96 4 75 mg ATT 0.046 155 2.99 5 150 mg ATT 0.045 162 2.97 6 75 mg NATT 0.047 144 2.95 7 150 mg NATT 0.049 155 2.92 8 75 mg EATT 0.050 219 3.01 9 150 mg EATT 0.054 209 2.9410 75 mg AATT 0.047 195 2.8411 150 mg AATT 0.057 251 3.0212 75 mg ClATT 0.047 166 2.9613 150 mg ClATT 0.046 174 2.8514 75 mg PMATT 0.048 138 2.8815 150 mg PMATT 0.045 155 2.8716 75 mg MATT 0.048 129 2.9617 150 mg MATT 0.051 117 2.9718 75 mg BATT 0.048 123 2.9519 150 mg BATT 0.045 132 2.8920 75 mg HATT 0.044 138 3.0121 150 mg HATT 0.043 144 3.0222 75 mg CNATT 0.047 126 2.8823 150 mg CNATT 0.044 129 2.88______________________________________

EXAMPLES 24-26

The procedure outlines in examples 1-3 was repeated with the iodobromide emulsion (B). The emulsion was tested with 75 mg/mole of both D1 and D3 and supersensitized with ATT. The sensitometric results are compiled in Table 3 was were obtained with a 660 nm narrow band filter for dye, D1 and a 700 nm narrow band filter for dye, D3. The data show that ATT supersensitivzed the iodobromide emulsion in the red region of the electromagnetic spectrum.

TABLE III______________________________________ Narrow Band ATT Filter FRESHEx. Dye (mg/mole) (nm) Dmin SPD CONT______________________________________E D1 -- 660 0.05 100 1.8724 D1 75 mg ATT 660 0.05 219 2.0725 D1 150 mg ATT 660 0.05 204 2.16F D3 -- 700 0.04 100 1.9926 D3 150 mg ATT 700 0.04 126 2.22______________________________________

Claims

1. A silver halide photographic emulsion in a hydrophilic colloidal binder, said emulsion being spectrally sensitized to the red portion of the electromagnetic spectrum and having a supersensitizing amount of a 5-substituted-amino-1,2,3,4-thiatriazole.

2. The emulsion of claim 1 wherein said amine group is a secondary amine group.

3. The emulsion of claim 1 wherein said 5-substituted-amino-1,2,3,4-thiatriazole is represented by the general formula ##STR4## wherein R is selected from the group consisting of alkyl groups, aryl groups, allyl, and 5- or 6-membered heterocyclic groups having only C, N, S or O ring atoms.

4. The emulsion of claim 3 wherein R is a phenyl group.

5. The emulsion of claim 3 wherein R is an alkyl group.

6. The emulsion of claim 4 wherein said phenyl group comprises a para-substituted phenyl group.

7. The emulsion of claim 6 wherein said phenyl group has a para-substituent selected from the class consisting of halogen, alkyl, alkoxy, and hydroxy.

8. The emulsion of claim 1 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consisting of thiazoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.

9. The emulsion of claim 2 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consisting of thiazoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, enzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.

10. The emulsion of claim 3 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine bye selected from the class consisting of thizaoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-inodolenines, imidazoles, and benzimidazoles.

11. The emulsion of claim 4 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consisting of thiazoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.

12. The emulsion of claim 5 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consisting of thiazoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.

13. The emulsion of claim 6 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consisting of thiazoles, benzothiazoles, [1,2-d]-naphthothiazoles, [2,1-d]-naphthothiazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.

14. The emulsion of claim 7 wherein said emulsion is sensitized by a merocyanine, carbocyanine, or dicarbocyanine dye selected from the class consistent of thiazoles, benzothiazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, oxazoles, benzoxazoles, selenazoles, benzoselenazoles, [1,2-d]-naphthoselenazoles, [2,1-d]-naphthoselenazoles, thiazolines, 4-quinolines, 2-pyridines, 4-pyridines, 3,3-dialkyl-indolenines, imidazoles, and benzimidazoles.