US2393763A - Salicylamide antifoggant - Google Patents

Description

Patented 1946 SALICYLAMIDE ANTIFOGGANT George E. Fallesen and John A. Lcermakers,

Rochester, N. Y.,

New Jersey assigno'rs to-Eastman Kodak Company, Rochester, N.

Y., a corporation of No Drawing. Application January is, 1944, Serial No. 518,123 I Claims. (ores-s8) This invention relates to fog inhibit rs for photographic emulsions" and to photographic emulsions containingthem.

It is known that photographic emulsions, particularly ultra-sensitive emulsions, exhibit a tendency to form a deposit of silver in the emulsion. This deposit extends more or less uniformly over the entire emulsion and is known as fog. Photographic fog is of two types, local and general. Local fog is formed by exposure of the film or plate at undesired points, as by a. light leak in the camera, or by local action of chemicals. General fog or, as it is sometimes known. chemical fog, is' formed in a number of Ways. It may be caused by the conditions under which the film or plate is stored, such as conditions of high temperature or unusually long time of storage.

The antiioggant properties of the hydroxy benzamide were tested as follows:

The nature of the emulsion may also produce chemical fee, as well as the conditions of development of the emulsion, as by development for protracted periods 01' time or at temperatures above normal. Highly sensitive emulsions are more likely to tog than those of lower sensi tivity. We arefconcerned primarily with general or chemical fog.

It is an object of the present invention to provide a fog inhibiting agent for ultra-sensitive photographic emulsions and thereby to preserve the emulsion against deterioration causing fog. A further object is to provide a novel antifoggantwhich does not markedly lower the sensitivity of the emulsions.

These objects are an exposed silver halide accomplished by developing emulsion in the presence of a hydroxy benzamide, such as salicylamide, preferably by incorporating it in the emulsion.

The hydroxy benzamide may be incorporated in an emulsion which is intended to be used directly after emulsification or one which is subjected to ripening. 'Salicylamide is very useful as an antifoggant in fast negative emulsions containing optical sensitizing dyes. The comthe following structure:

pound has In addition tosalicylamide, m-hydroxy benzamide and p-hydroxy benzamide may also be used.

. ding and washing.

'tions originating from the same Silver iodobromide was precipitated in 0.8% gelatin solution. After precipitation was complete, this entire volume of emulsion was cooled and divided into portions weighing 1643 grams each. To each portion was added enough gelatin to increase the gelatin concentration to approximately 6.6%. Each portion was then heated to the required digestiontemperature, that is, about C. and as soon as this temperature was reached a certain amount oi the compound to be tested, e. g., 25 grams or salicylamide, dissolved in 300 cc. ofmethyl alcohol, was added. Di-

30 minutes at the specified temperature and the emulsion was then chilled and stored in preparation for shred- One of these portions received no additions other than the required gelatin and it served as the control for all the porsilverjhallde.

After washing, each emulsion was heated to the optimum point for maximum speed and gamma with acceptable fog. Unsensitlzed-and panchromatized samples oi! each emulsion so finished were coated by machine After the plates were dry, 9. series oi sensitometric tests were made on them. The data were then compared with those of the check emulsion containing no addendum. These tests include initial tests for speed, gamma and fog, made on the day after coating, similar tests on a second set of plates incubated at 120 F., dry heat, for 6 or'14 days and a third set of tests made on a third set of plates after having been kept under tropical conditionsior 14' days. (The "tropical conditions are simulated by varying the temperature and humidity through a cycle to reproduce day and night conditions in tropical climates.) Plates for each 0! these tests were developed for 3 minutes at F. in Kodak D-19 developer which had the following composition:

Monomethyl-p-amlnophenol sulfate Sodium sulflte (desiccated) -do 96 Hydroquinone do Sodium carbonate (desiccated) do.. 48 Potassium bromide -do 5 Water to ers" 1 precipitation of l on glass plates.

rams 2.2

The results of these tests are tabulated below; s)

aseavoa Tropical condition 14 day 120 1". dry Initial iog tests day incubation fog incubation I r t ts iog tests Salicylamide v Emulsion Emulsion Emulsion Emulsion Emulsion Emulsion with without with without with without compound compound compound compound compound compound 1.5 g. per litc.' 0.04 0.05 0.12 0.16 3g.perliter .05 .05 .11 .16 6.3 g. per liter .04 .06 .07 l6 12.5g.perliter...-.. .05 .06 0.06 0.08 .30 .36

l 14 day; i

The amount of fog was determined by reading the density of the unexposed area. of the plate after exposure and development of the emulsion, in the usual manner. 1

The amount of fog inhibiting agent used in the emulsion will depend upon the composition 01 the agent and upon the typeot emulsion. In

general, the amount of fog inhibiting agent used will vary from 1 gram to 15 grams perlOOO cc. of wet emulsion. It will be understood that more or less than this amount may be used. Generally, however, if a greater amount is used in the emulsion, either no increased fog inhibiting efiect is obtained or there is a decrease in the sensitivity of the emulsion. The antifoggant may be incorporated by mixing it with any suitable solvent which is inert with sion such as water, methyl alcohol, ethyl alcohol,

acetone and others.

The fog inhibiting agent which we have described maybe used in various kinds of photographic emulsions, In addition to being useful in ordinary non-sensitized emulsions, it 'may be used in orthocnromatic, panchromaticv and X-ray emulsions. Various silver salts may be used as the sensitive salt such as silver bromide, silver chloride. silver bromiodide, and silver chloro bromide The dispersing agent may be gelatin or other suitable colloid such as collodion, albumen, cellulose organic derivatives or synthetic resins.

respect to the emul- In addition to its use in the sensitive emulsion itself, curios inhibiting agent may also be incorporated .in an layer in the photographic element containing the sensitive emulsion layer.

It is to be understood that we contemplate as included within our invention all modifications and equivalents tailing within thescope oi the appended claims.

We claim:

1. A gelatino-silver halide'emulsion containing a tog-inhibiting amount 01 a hydroxy benzamide.

2. 4i gelatino-silver halide emulsion containing a fog inhibiting amount of salicylamide.

3. A gelatino-silver halide emulsion containing from 1 to 15 grams per liter of wet emulsion of salicylamide. I

4. The method 01' reducing the amount of fog produced-upon development'or a silver halide emulsion which comprises developing said emulsion in the'presence of a fog-inhibiting amount oi a'hydrox benzamide.

5. The method of reducing the amount or reg produced upon development or a silver halide emulsion which comprises developing said emulsion in the presence or a tog-inhibiting amount of salicylamide.

anoaan n. r-Amnsm. JOHN A, 0104' :om-

overcoating or intermediate 7