US2449836A

US2449836A - Photographic silver halide emulsions

Info

Publication number: US2449836A
Application number: US592057A
Authority: US
Inventors: Blake Ralph Kingsley
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1945-05-04
Filing date: 1945-05-04
Publication date: 1948-09-21
Anticipated expiration: 1965-09-21

Description

Patented Sept. 21, 1 948 PHOTOGRAPHIC SILVER HALIDE EMULSION S Ralph Kingsley Blake, Parlin, N. J., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del, a corporation of Delaware No Drawing. Application May 4, 1945, Serial No. 592,057

8 Claims.

This invention relates to photographic silver halide emulsions of improved stability. More particularly it relates to photographic silver halide emulsions and emulsion layers which contain small amounts of lower monoalkylaminomonohydroxybenzenes.

Photographic elements deteriorate upon aging and ordinarily should be used within a year or two after manufacture if one is to obtain satisfactory results. This means that photographic elements should be used within such period in order to obtain good results. The deterioration of photographic elements upon aging generally results in a chemical fog which aflects the sensitivity and developability thereof. The formation of this fog is accelerated by the advance of time and temperature. Many proposals for controlling chemical fog have been made and while some are meritorious they involve the use of chemicals which are not always readily available. Others while improving the stability of emulsion layers decrease the sensitivi-ty.

An object of this invention is to provide photographic silver halide emulsions of satisfactory stability. A further object is to provide such emulsions without deleteriously affecting their sensitivity to light. A related object is to provide photographic films, plates, and paperswith silver halide emulsion layers which remain stable for long periods of time in hot climates. Another obiect is to provide a simple and economical means for stabilizing silver halide emulsion layers. Still other objects will be apparent from the following description of the invention.

The above objects are accomplished by incorporating with a colloid-silver halide emulsion a small amount of a lower monoalkylaminomonohydroxybenzene. The alkyl group attached to. the amino nitrogen atom may contain from 1 to 2 atoms. The monoalkylamino monohydroxybenzenes may be used in the form of the base or in the form of an addition salt, e. g., the hydrochloride or sulfate. The salts are preferred because of their stability and increased solubility in water.

The above compounds may be added at various stages during the manufacture of colloid silver halide emulsions or dispersions r emulsion layers but are preferably added to the emulsions prior to coating. The alkylaminohydroxybenzene compounds may be added to an aqueous colloid solution, such as gelatin, and mixed with a colloid silver halide emulsion or the colloid solutions may be used as a substratum coating the alkylaminohydroxybenzenes with the emulsion layers would be to bathe a silver halide emulsion layer with an aqueous solution containing such compounds.

To be more specific, colloid silver halide emulsions essentially composed of silver bromide and especially those containing small amounts, e. g., 0.5 to: 10% of silver iodide may be effectively stabilized by the addition of from 0.0015 to 0.03 gram of a lower monoalkylaminomonohydroxybenzene per grams 'of silver halide. The compounds when used in these small amounts do not exhibit any discernible developing action upon exposed silver salts when elements containing the same are immersedin an alkaline solution, e. g., caustic soda solution of 1 per cent strength. Small amounts of alkaline sulfite, e. g., sodium sulfite, potassium sulfite, ammonium sulfite, etc., for instance, about 10' to 50 times that of the alkylaminohydroxybenzene compound are desirable in the emulsions because:

it prevents a possible loss in speed. The compounds, however, do reduce the general or chemical fog to a marked extent and increase the stability of the emulsion layers upon aging. The

compounds do not have any significant effect upon the sensitivity of the emulsionlayersand have a. fog inhibiting action.

The invention will be further illustrated but is not intended to be limited by the following examples. The parts are by weight.

To portions of a gelatinoesilver halide emulsion containing. 6.8 per cent molar silver iodide and 93.2 per cent molar silver bromide and a small amount of sodium sulfite were added the N-methyl-para-aminophenol sulfate grams 0.8 Hydroquinone do- 1.0 Sodium sulfite (anhydrous) do 900 Borax do 3.0 Potassium bromide do 0.1

Water to "liters; 1

for 7 minutes at 68 F. with the results listed in the following table:

Fresh-film tested fresh Room-film held approximately 1 week at room temperature after coating before testing O venfllm held approximately 1 week at 120 F. after coating before testing EXPERIMENT No. 1

N'-methylpara-amino- Film Relative phenol sulfate Age Speed Gamma Fog Fresh. 528 75 13 Control Rcom 400 71 16 Ovenm. 264 65 .33 Fresh. 493 79 10 0.0025 g Room... 400 73 .06

ven. 325 74 15 Fresh. 493 76 07 00050 g Room 400 76 07 Oven 303 71 .15

EXPERIMENT N0. 2

N-methyl-para-amino- Film Relative phenol sulfate Age Speed Gamma Tog Fresh 400 78 14 Control Room 373 78 10 Oven 214 70 31 Fresh 400 78 12 0.0050 g Room 373 78 10 Oven 283 71 21 Fresh 373 78 12 0.0067 g Room 303 75 .09 Oven 264 72 15 Fresh 373 .76 12 0.0083 g Room 325 .76 09 Oven 283 78 15 Similar results were obtained without the sulfite with an insignificant loss in speed.

In place of the particular monoalkylaminomonohydroxybenzene compound described in the above experiments there may be substituted various other salts coming within this class. Suitable additional compounds include N-methyl-paraaminophenol hydrochloride, N-ethyl-para-aminophenol sulfate, N ethyl para aminophenol, N methyl-para-aminophenol, N-methyl para-- aminophenol hydrochloride.

Various emulsion components may be used in conjunction with the. monoalkylaminomonohydroxybenzenes. For example, color formers, hardeners, sensitizing dyes, wetting agents, fog inhibitors, and the like may be'present in the emulsion in addition to the silver salts and the monoalkylaminomonohydroxybenzenes, General emulsion sensitizers, such as sodium sulfite, may advantageously be used with such compounds. A suitable emulsion, for example, may contain in addition to the gelatin, silver iodide and silver bromide, small amounts of thymol, alkali sulfite, alcohol, a cyanine dye, a soluble bromide, saponin, and alum.

Colloid binding agents other than gelatin may be used in the emulsions and emulsion layers. Suitable additional hydrophilic colloids include albumin, polyglycuronic acid, hydrophilic cellulose derivatives, e. g., ethers and carboxylic acid esters, vinyl alcohol polymers and interpolymers and polyamides. These colloids may be substituted in whole or in part for the gelatin.-

The invention has many advantages.

It provides a means for obtaining stable emulsions and emulsion layers in a simple and economical manner. Another advantage resides in the fact that photographic elements containing such emulsions are readily obtained without any significant loss in sensitivity. A further advantage resides in the fact that the novel elements have good stability in hot climates.

As many widely different embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims. J

What I claim is: y

l. A colloid silver bromide emulsion containing from 0.0015 to 0.03 gram of N-alkylaminomonohydroxybenzene having from 1 to 2 carbon atoms in the alkyl radical per grams of silver halide.

2. A gelatino-silver iodobromide emulsion containing from 0.0015 to 0.03 gram of N-alkyl-paraaminophenol having from 1 to 2 carbon atoms in the alkyl group per 100 grams of silver halide.

3. A gelatino-silver iodobromide emulsion layer containing from 0.0015 to 0.03 gram of N-methylpara-aminophenol sulfate per 100 grams of silver halide.

4. A gelatino-silver iodobromide emulsion layer containing from 0.0015 to 0.03 gram of N-methylpara-aminophenol sulfate and a small amount of an alkaline sulfite per 100 grams of silver halide.

5. A photographic element bearing at least one hydrophilic colloid-silver iodobromide emulsion layer which contains 0.0015 to 0.03 gram of a lower monoalkylaminomonohydroxybenzene per 100 grams of silver halide.

6. A photographic element bearing at least one hydrophilic colloid-silver bromide emulsion layer which contains 0.0015 to 0.03 gram of N-alkylaminomonohydroxybenzene having from 1 to 2 carbon atoms in the alkyl group per 100 grams of silver halide.

7. A photographic element bearing at least one hydrophilic colloid-silver iodobromide emulsion layer which contains 0.0015 to 0.03 gram of N-alkyl-para-aminophenol having from 1 to 2 carbon atoms in the alkyl group per 100 grams of silver halide.

8. A photographic element bearing at least one gelatino-silver iodobromide emulsion layer which contains 0.0015 to 0.03 gram of N-methyl-paraaminophenol sulfate per 100 grams of silve halide.

, RALPH KINGSLEY BLAKE.

, REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain 1898