US3791830A

US3791830A - Silver halide photographic element containing a reaction product of a heterocyclic mercaptan and a chloroformic acid ester as antifog agent

Info

Publication number: US3791830A
Application number: US00362737A
Authority: US
Inventors: W Abele
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1970-12-16
Filing date: 1973-05-22
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: DE2061972A1; DE2061972C3; DE2061972B2; JPS559696B1; BE776719A; GB1357037A

Abstract

Photographic material is stabilized against over-development wherein the emulsion layer or an auxiliary layer in contact with emulsion layer contains an antifogging agent of the formula

Description

United States Patent Abele Feb, 12, 1974 1 SILVER HALIDE PHOTOGRAPHIC [56] References Cited ELEMENT CONTAINING A REACTION UNITED STATES PATENTS PRODUCT OF A HETEROCYCUC 3,364,028 H1968 Von Konig 96/109 MERCAPTAN AND A CHLOROFORMIC 2,394,198 2/1946 Mueller 96/109 AC") ST S ANTTF G AGENT 3,365,294 1/1968 Von Konig 96/109 Werner Abele, Friedrich-List-Strasse, Germany Inventor:

E. J. du Pont de Nemours and Company, Wilmington, Del.

Filed: May 22, 1973 Appl. No.: 362,737

Related U.S. Application Data Continuation-impart of Ser. No. 207,593, Dec. 13, 1971, abandoned.

Assignee:

Foreign Application Priority Data Dec. I6, 1970 Germany 2061972 U.S. Cl. 96/76 R, 96/109 Int. Cl G03c l/34, G030 l/48 Field of Search 96/109, 76 R Primary Examiner.l. Travis Brown Assistant Examiner-Won H. Lovie, Jr.

A is a nitrogen-containing heterocyclic radical having 5 or 6 atoms in the heterocyclic ring; Y is S for n l and S or S and NH for n 2; R is any desired substituent such as alkyl, halogen or hydroxyalkyl; Z is S or 80:; and n is l or 2.

where 8 Claims, No Drawings SILVER HALIDE PI-IOTOGRAPIIIC ELEMENT CONTAINING A REACTION PRODUCT OF A HETEROCYCLIC MERCAPTAN AND A CHLOROFORMIC ACID ESTER AS ANTIFOG AGENT CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of.U.S. application Ser. No. 207,593, filed Dec. I3, 1971, now abandoned.

BACKGROUND OF THE INVENTION The subject of the present invention is a photographic material with at least one light-sensitive, silver halide emulsion layer that is stabilized against overdevelopment.

If photographic materials must be processed under intensified conditions, for example, with the use of highly active developer solutions, with development at relatively'high temperatures, or-with extremely long time of development, there is a danger that silver halide grains not carrying latent image nuclei also will be reduced. The fog produced by..this undesirable reduction of unexposed grains appears under the abovementioned unfavorable conditions especially strongly at the end of the normal developing process and, accordingly, is designated as overdevelopment fog. This overdevelopment cannot be prevented by conventional stabilizers or can be prevented only with abandonment of optimum sensitivity utilization.

Thus, for example, stabilizers from the class of the triazaindolizines, which are outstandingly suitable for the prevention of fog on storage, give no protection against overdevelopment, because their protective action declines and practically disappears at the end of development, through removal by diffusion and other mechanisms, when it is most needed. Other stabilizers with known effectiveness, such as mercury compounds or heterocyclic mercapto compounds are indeed able to reduce the development fog considerably in the normal development and also in the overdevelopment region, but have the great disadvantage that when used in sufficient amounts they reduce the utilizable sensitivity of the photographic emulsion considerably.

A fundamental disadvantage of the direct addition to silver halide emulsions of heterocyclic mercapto compounds, that are known to be particularly effective against overdevelopment fog, is that they are completely active starting from the time of addition, that is, also during the casting process, during the entire time of storage of the unprocessed film material and, finally, in the initial stage of photographic development. Therefore, even before the processing, desensitizing effects occur, and during the development itself the inherent sensitivity of the material is not completely utilized. To solve this problem, substitution of the mer capto groups of these compounds by suitable radicals has already been tried, which is supposed to inactivate them until a time when they should become active. Therefore, in principle, the compounds can be added to the light-sensitive emulsion without damage, since the active groups are liberated first during the development process. It is important to know, however, the time at which the reactivation of the protected group takes place because if reactivation takes place too slowly, the overdevelopment fog is not sufficiently hindered; and if it takes place too rapidly, the image build up is impaired. In both instances an optimum sensitivity/fog ratio cannot be achieved.

From the German patent specification 1,173,336 and the US. Pat. No. 3,260,597, mercapto stabilizers are known, the active groups of which are protected by a carboxylic acid or a sulfonic acid group. However, these acyl radicals have the disadvantage that they are split off too rapidly in alkaline medium, that is, the active group is liberated already before the conclusion of image build up, which leads to marked losses in image density.

In contrast thereto, the thioethers described in the U. S. Pat. Nos. 2,981,624 and 3,260,597 and also the German Offenlegungsschrift 1,908,217 reactivate much too slowly and, therefore, cannot prevent the overdevelopment fog to the extent desired.

From the German Patent 1,189,380, mercapto stabilizers are known which have a carbethoxy protective group and are used to prevent yellow fog in photographic papers. These compounds also impair the sensitivity of the emulsion considerably, because the reactivation takes place too fast.

Finally, from the Offenlegungsschu'ft 1,597,503 stabilizers are known the mercapto groups of which are reacted with phosgene or isocyanates. However, these derivatives likewise are reactivated too fast or cannot be cleaved in the developer so that they are practically without effect on the overdevelopment fog.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide antifog agents with one or more inactivated mercapto groups, which are liberated for the foginhibiting reaction first after the conclusion of the image build up in the photographic development, but before the otherwise expected marked increase of the fog curve. In doing this new compounds, were found that were especially active against the overdevelopment fog and that, in their functionally guided action, are superior to the known antifog agents. They correspond to the general formula:

in which:

A a nitrogen-containing heterocyclic radical having 5 or 6 atoms in the heterocyclic ring Y=Sforn= l andSorSandNH-forn=2,

Z S or S0 and n l or 2.

The invention therefore relates to photographic material comprising a film support and at least one lightsensitive silver halide emulsion layer, said emulsion layer being in contact with an antifog agent of the formula given above. Contact between the antifog agent and the emulsion layer may be effected by incorporating the antifog agent in the emulsion or by incorporating the antifog agent in an auxiliary layer that is in contact with the emulsion.

DESCRIPTION OF PREFERRED EMBODIMENTS Suitable materials for the film support, the silver halide emulsion layer and the optional auxiliary layer will be apparent to those skilled in the art.

wherein A, Y, Z and n are defined as above and R= any desired substituent, for example, alkyl, halogen, or hydroxyalkyl.

Preparation of the new antifog agents is accomplished by reaction of the antifog agents containing mercapto groups with chloroformic acid esters in the presence of acid acceptors and can be represented by the following reactions:

in which A li and Z have the meanings given above and in which, as in the formulae below, R may or may not be present. The preparation of the chloroformic esters (I), that have a methyl group in the p-position of the phenyl nucleus, is described by T. A. Kader and D. .l. M. Stirling in Proc. Cham. Soc. 1962, page 363.

However, the synthesis can also be carried out using B-bromoethyl chloroformate according to the following reactions:

Examples of antifog agents within the general formula given above are listed in the following table:

TAnLE Compound @N-fis0o-0Hr0H,-s@-0Ha N\ /N N 2 0 ll N- fis -0-0H0H2s N N CH3 ?t N N 4 v p "m i @I II-(IfSC-OCHICHZ-S@Cl N N N (I? l @I\II-(ILI-SC-OCH2-CH:S-@C1 (I? l l TABLE- Continued Compound The preparation of the Tndivid ual compounds is described in the following:

COMPOUND l.

The potassium salt of l-phenyl--mercaptotetrazole (10.8 g 0.05 mol) is dissolved in 300 ml of acetone and reacted dropwise with stirring at 5 C. with 1 1.5 g (0.05 mol) of p-tolylthioethylene chloroformate in 50 ml of anhydrous acetone. At the end of the addition, the reaction mixture is stirred for another 5 hours at room temperature and allowed to stand overnight. Subsequently, the mixture is heated to boiling, the precipitated potassium chloride is filtered off and the filtrate is concentrated in vacuo. The oily residue is recrystallized repeatedly from a little ethanol.

Yield: ca. 60 percent of the theoretical; mp 47 C.

COMPOUND 2.

The synthesis was accomplished analogous to that of compound 1 by reaction of the potassium salt of l-phenyl-5-mercaptotetrazole with U5 g (0.05 mol) of mtolylthio-ethylene chloroformate.

Yield: ca. 60 percent of the theoretical; mp 40 C.

COMPOUND 3.

The potassium salt of l-phenyl-5-mercaptotetrazole (l0.8 g 0.05 mol) is dissolved in 300 ml of acetone and reacted dropwise with stirring at 5 C. with 10.8 g of phenylthioethylene chloroformate (0.05 mol) in 50 ml of anhydrous acetone. At the end of the addition, the reaction mixture is stirred for another 5 hours at room temperature and allowed to stand overnight. Subsequently, the mixture is heated to boiling, the precipitated potassium bromide (7) is filtered off and the filtrate is concentrated in vacuo. The oily residue is recrystallized repeatedly from a little ethanol.

Yield: ca. percent of the theoretical; mp 53 C.

COMPOUND 4.

The synthesis was accomplished analogous to that of Compound 1 by reaction of l-phenyl-S- mercaptotetrazole with 12.6 g (0.05 mol) of p-chlorobenzenethioethylene formate.

Yield: ca. 50 percent of the theoretical; mp 58 C.

COMPOUND 5.

The potassium salt of 1-phenyl-S-mercaptotetrazole 712' 0.0'3'3'hib1' is dissolved in 200 ml of acetone and reacted with stirring at C. with 6.2 gof (0.033 mol) of B-bromoethyl chloroformic acid. The solution is allowed to stand overnight, subsequently filtered and the filtrate is concentrated in vacuo. The oily residue consisting of l-phenyl-S-(B-bromoethyl thiocarboxylate)-tetrazole is used without further purification for the following reaction: 2,4,S-Trichlorothiophenol (6.4 g 0.03 mol) is dissolved in 100 ml of acetone and reacted with 9.9 g (0.03 mol) of l-phenyl-S-(B- bromoethyl thiocarboxylate)-tetrazole in 50 ml of acetone with the addition of 1.2 g (0.03 mol) of magnesium oxide. The slurry is heated under reflux for 4 hours, filtered and the acetone solution is concentrated in vacuo. The residue is recrystallized repeatedly from methanol.

Yield: 8.7 g (63% of the theoretical); mp 138 C.

COMPOUND 6.

The synthesis is carried out like that of Compound 5 with 8.5 g (0.03 mol) of pentachlorothiophenol.

Yield: 75 g (47 percent of the theoretical); mp 98 C.

COMPOUND 7.

The preparation is analogous to that with Compound 1 with 13.1 g of p-tolylsulfonylethylene chloroformate.

Yield: ca. 60 percent of the theoretical; mp 115 C.

COMPOUND s.

1 -Phenyl-5-( B-bromoethyl thiocarboxylate)- tetrazole (9.9 g 0.03 mol) in 150 ml of acetone is heated under reflux for 4 hours with 6.0 g (0.03 mol) of sodium p toluenesulfinate. After filtering, the acetone solution is concentrated in vacuo and the residue is recrystallized repeatedly from methanol.

Yield: 9.2 g (68 percent of the theoretical; mp 137 COMPOUND 9.

Z-Mercaptobenzothiazole (3.4 g 0.02 mol) is treated with 0.8 g (0.02mol) of magnesium oxide in 200 ml of COMPOUND 10.

The synthesis is carried out analogous to that of compound 9 with 5.4 g (0.02 mol) of ptolylsulfonylethylene chloroformate.

Yield: 2.5 g (32 percent of theoretical) mp 153 C.

COMPOUND 11.

2,5-Dimercaptothiodiazole (3.0 g 0.02 mol) is dissolved in 200 ml of acetone and treated with 1.6 g (0.04 mol) of magnesium oxide. To this slurry is added dropwise with stirring at 5 C. a solution of 9.2 g (0.04

mol) of p-tolythioethylene chloroformate in 50 ml of anhydrous acetone. After addition is completed the mixture is stirred at room p-tolylthioethylene for an- 5 other 5 hours and allowed to stand overnight. Subsequently, the slurry is heated to boiling, filtered and the acetone solution is concentrated in vacuo. The residue is recrystallized from a little ethanol.

Yield: 6.5 g (61 percent of the theoretical); mp 94 C.

COMPOUND 12.

The synthesis is carried out analogous to that of Compound 11 with 10.5 g (0.04 mol) of p-tolylsulfonyl-ethylene chloroformate.

Yield: 6.0 g (50 percent of the theoretical); mp 151 C.

COMPOUND 13.

2-Amino-5-mercaptothiodiazole (4.0 g 0.03 mol) is dissolved in 250 ml of acetone and treated with 2.4 g (0.06 mol) of magnesium oxide. To this slurry is added dropwise with stirring at 5 C. a solution of 13.9. g (0.06 mol) of p-tolylthioethylene chloroformate in 50 ml of anhydrous acetone. After addition is completed the mixture is stirred at room temperature for another 5 hours and allowed to stand overnight. Subsequently, the slurry is heated to boiling, filtered hot, and the hot acetone solution is concentrated in vacuo. The oily residue is recrystallized repeatedly from ethanol.

Yield: 11.1g (71 percent of the theoretical); mp 143 C.

COMPOUND 14.

COMPOUND 15.

The synthesis is carried out like that of compound 13 with 15.0 g (0.06 mol) of benzenesulfonylethylene chloroformate. Yield 9.7 g (58 percent of the theoretical); mp 178 COMPOUND 16.

The synthesis is carried out like that of compound 13 with 15.8 g (0.06 mol) of p-toluenesulfonylethylene chloroformate.

Yield 1 1.4 g (65 percentof the theoretical); mp 168 To produce the light-sensitive materials, the antifog agents are added to the light-sensitive emulsions or also to the light-insensitive auxiliary layers, such as interlayers, protective layers and the like. Addition is accomplished most advantageously before casting the emulsions, but it is possible also to add the compounds at another time in the emulsion production. With use in the emulsion layer itself, the compounds preferably are added in quantities of 0.05 to 5 mmol based on 1.0 mol of silver halide, whereas in the auxiliary layers they display the best action in quantities of 0.1 to 5 mmol. Naturally, the optimum quantity at the time depends on the nature of the antifog agent and the emulsion used and can be determined easily from case to case.

The compounds described can be dissolved in a suitable solvent and added to the emulsion in this form. In

case the solubility of the compounds is too low in wa- EXAMPLE 2.

To a silver bromide-iodide emulsion prepared according to the data in Example I is added, per mol of silver bromide, an acetone soltuion of 0.3 mmol of the ter-miscible organic solvents, they also can be dissolved compound 2 of the table, and cast exposed and in a known manner in water-immiscible organic solcessed as in Example 1' ventsand added the form ofa p Examples Thereby, the results recorded in the table were obof suitable solvents are 4-phenyl-l,3-d1oxan, trlbutyl tained: phosphate, diethyl phthalate, ethyl acetate, phenyl glycol etc Sample 35 C. 39 C.

' Sensitivity Fog Sensitivity Fog The new antifog agents can be used in the most varied kinds of recording materials, for example, in opti- A 22:33: 010 107 042 cally unsensitized materials like X-ray films, but also in B 102 (m9 120 0,11 orthochromatic and panchromatic sensitized recording g v i 2 materials. Besides, the light-sensitive emulsions used tabe can contain the customary additives, such as chemical sensitizers, hardeners, wetting agents, and the like. EXAMPLE 3,

The new antlfog. agents b used in mixtures with To a silver bromide-iodide emulsion prepared acone another or in combination with other antifog a ems cording to the data in Example 1 is added, per mol of 'fouowin exam es will illustrate th inv mio silver bromide, an acetone solution of 0.2 mmol of the g p e e n m compound 3 of the table, and cast, exposed and prodetail, however, w1thout l1m1t1ng 1t in any way. cessed as in Example 1 I EXAMPLE 1 Thereby, the results recorded in the table were obtained:

An optically unsensitized, h1gh-sens1t1v1ty silver halide emulsion is produced which contains about 5 persamph cent of gelatin and about 10 percent of silver halide. Sensitivity 2 Sensitivity 1; The silver halide consists of 98 weight per cent of silver A comparison m0 0 120 033 bromide and 2 weight per cent of silver iodide. The emulsion emulsion produced in this way is divided into two parts 8 compound; 125 A and B. Part A contains no additive and serves as a of table comparison sample. To part B, per mol of silver bromide is added a solution of 0.3 mmol of the compound EXAMPL l of the table, dissolved in acetone.

The emulsion is cast on a polyester film base and the 3. a i i g i gg grepared light-sensitive material obtained is evaluated in the mg 0 e a a m Xamp e a e per m0 0 usual way silver bromide, an acetone solut1on of 0.2 mmol of the And, in fact, the samples, in the form of the known compgund, r and cast exposed and test strips, are exposed for 2 sec with two Osram lamps 40 cesse as m d h b (Wi 9 2,660 K.) at a distance of 1.2 m in a grey-wedge f t e ts recor e m t e ta 6 were 0 sensitometer with a wedge constant of D 0.15/cm tamed with filters BG 3 (1.8 mm) and BG 38 (1.5 mm), and sample 5 gb: then developed for 25 sec at temperatures of 35 C. and Sensitivity Fog Sensitivity Fog 39 C. in a developer with the following composition:

A companson 100 0.19 120 0.35

emulsion 100 0.11 123 0.16 compound 4 Hydroquinone 30.00 g in table l-Phenyl-3-pyrazolidone L00 3 Na,SO (anhydrous) 60.00 g KOH 23.00 g mam-411,0 2000 g EXAMPLE 5. make To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of The films are fixed a customary fixmg bath silver bromide, an acetone solution of 0.4 mmol of the Subsequently ,washed and dried compound 5 of the table, cast and exposed as in Exam- The following results were obtamed, in WhlCh for ple l and developed for 3 min and 12 min at C in simplicity of comparison, the value for the general senthe developer given there s1t1v1ty of the comparison emulslon was set equal to Thereby, the results recorded in the table were tained:

I Sample 35 C. 39 C. Sample 3 min development l2 min development Sensitivity Fog Sensitivity Fog Sensitivity Fog Sensitivity Fog A comparison I00 0.l9 NS 0.40 A comparison 0.06 I45 0.32

emulsion 65 emulsion a 101 0.10 0.13 B 98 0.05 148 0.14

compound l compound 5 of table in table EXAMPLE .6.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.4 mmol of the compound 6 of the table, cast and exposed as in Example l and developedfor 3 min and 12 min at 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development 12 min development Sensitivity Fog Sensitivity Fog A comparison 100 0.04 132 0.27

emulsion 100 0.03 144 0.13 compound 6 in table EXAMPLE 7.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.2 mmol of the compound 7 of the table, cast and exposed as in Example l and developed for 3 min and 12 min at 20 C. in the, developer given there.

Thereby, the results recorded in the table were ob- To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.3 mmol of the compound 8 of the table, cast and exposed as in Example 1 and developed for 3 min and 12 min at 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development 12 min development Sensitivity Fog SEnsitivity Fog A comparison 100 0.04 144 0.26

emulsion 110 0.03 158 0.13 compound 8 in table EXAMPLE 9.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.1 mmol of the compound 9 of the table, cast and exposed as in Example 1 and developed for 25 sec at temperatures of 35 C. and 39 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 35 C. 39C.

Sensitivity Fog Sensitivity Fog A comparison 0.15 128 0.43

emulsion B 0.08 140 0.13

compound 9 in table EXAMPLE 10.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.1 mmol of the compound 10 of the table, cast and exposed as in Example 1 and developed for 3 min and 12 min at 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development 12 min development Sensitivity Fog Sensitivity Fog A comparison 100 0.06 132 0.36

emulsion 98 0.04 132 0.14 compound 0 in table EXAMPLE 11.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.1 mmol of the compound 11 of the table, cast and exposed as in Example l and developed for 3 min and 12 min at 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample. 3 min development 12 min development Sensitivity Fog Sensitivity Fog A comparison 100 0.04 141 0.32

emulsion B 102 0.03 148 0.17

compound 11 in table EXAMPLE 12.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.1 mmol of the compound 12 of the table, cast and exposed as in Example 1 and developed for 25 sec at temperatures of 35 C. and 39 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 35 C. 39 C.

Sensitivity Fog Sensitivity Fog A comparison 100' 0.18 107 0.42

emulsion B 112 0.12 0.19

compound 12 in table EXAMPLE 13.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.2 mmol of the compound 13 of the table, cast and exposed as in Example 1 and developed for 3 min and 12 min at 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development -12 min development Sensitivity Fog Sensitivity Fog A comparison 100 0.04 126 0.30

emulsion B 100 0.03 132 0.13

compound 13 in table EXAMPLE 14.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.2 mmol of the compound 14 of the table, cast and exposed as in Example 1 and developed for 3 min and 12minat 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development 12 min development Sensitivity Fog Sensitivity Fog A comparison 100 0.05 129 0.26

emulsion 109 0.05 138 0.12 compound 14 in table EXAMPLE 15.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, and acetone solution of 0.1 mmol of the compound 15 of the table, cast and exposed as in Example 1 and developed for 3 min and 12 min at C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development 12 min development Sensitivity Fog Sensitivity FOg A comparison 100 0.4 132 0.35

emulsion B 98 0.3 126 0.09

compound 15 in table EXAMPLE 16.

To a silver bromide-iodide emulsion prepared according to the data in Example 1 is added, per mol of silver bromide, an acetone solution of 0.1 mmol of the compound 16 of the table, cast and exposed as in Example 1 and developed for 3 min and 12 min at 20 C. in the developer given there.

Thereby, the results recorded in the table were obtained:

Sample 3 min development 7 12 min development Sensitivity Fog Sensitivity Fog A comparison 0.5 129 0.32

emulsion B 0.4 129 0.1 1

compound 16 in table EXAMPLE 17.

A silver bromide-iodide emulsion prepared according to Example 1 is divided into 5 parts. Whereas, part A is cast on a polyester base unchanged as a comparison, the parts B, C, D and E are treated with acetone solutions of the following additives:

B 0.2 mmol of l-phenyl-5-carbethoxythiotetrazole (compound 4 of German Pat. 1,189,380). C 0.4 mmol of 1-phenyl-5-diethylcarbamoylthiotetrazole (compound 8 of the Offenlegungsschrift' 1,597,503) (OLS).

D 0.2 mmol of bis-1-phenyl-tetrazolyl-5- dithiocarboxylic acid ester (compound 1 of the OLS 1,597,503).

0.4 mmol of l-phenyl-S-ptolylthioethylenecarboxythiotetrazole (compound 1 of the table).

The exposed test strips were developed for 3 min and 12 min at 20 C. with the developer mentioned in Example 1, subsequently fixed in a customary fixing bath, washed and dried.

Evaluation gave the following results:

12 min development 3 min development Sensitivity Fog Sample Sensitivity Fog As is evident, with the previous state of the art (B, C and D) adequate improvement of the overdevelopment fog cannot be achieved without loss in sensitivity.

The advance achieved with the invention consists in that the overdevelopment fog can be reduced without the appearance of a loss in sensitivity. Beyond this, as a result of the better functional controllability of the reactivation process in the compounds of the invention,

it is possible to produce emulsions with an improved sensitivity/fog ratio and, in fact, both under normal and also under overdevelopment conditions. Consequently, the new compounds are superior in effectiveness to the known inactivated antifog agents.

1 claim:

1. Photographic material comprising a film support and at least one light-sensitive silver halide emulsion layer,'containing an antifog agent or being in contact with an auxiliary layer containing an anti-fog agent, said antifog agent having the general formula:

5. Photographic material according to claim 1 wherein the phenyl group attached to Z bears a substituent selected from alkyl, halogen, or hydroxyalkyl.

6. Photographic material according to claim 2 wherein the antifog agent has the following formula:

i hBibgr'iiiic material according to claim Z wherein the antifog agent has the following formula:

8. Photographic material according to claim 1 wherein said antifog agent is contained in said auxiliary layer in contact with said light-sensitive silver halide emulsion layer.

Claims

2. Photographic material according to claim 1, wherein A represents a 1-phenyltetrazolyl radical.
3. Photographic material according to claim 1, wherein A represents a benzthiazolyl radical.
4. Photographic material according to claim 1 wherein A represents a thiodiazolyl radical.
5. Photographic material according to claim 1 wherein the phenyl group attached to Z bears a substituent selected from alkyl, halogen, or hydroxyalkyl.
6. Photographic material according to claim 2 wherein the antifog agent has the following formula:
7. Photographic material according to claim 2 wherein the antifog agent has the following formula:
8. Photographic material according to claim 1 wherein said antifog agent is contained in said auxiliary layer in contact with said light-sensitive silver halide emulsion layer.