US2410690A - Method of improving the sensitivity characteristics of emulsions - Google Patents

Description

Patented Nov. 5, 1946 mitten UNITED STATES "PATENT OFFICE METHOD OF IMPROVING THE SENSITIVITY CHARACTERISTICS OF EMULSIONS William F. Smith and Robert E. Stauffer, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application August 26, 1943,

- Serial No. 500,087

9 Claims.

This invention relates to photographic emulsions and particularly to a method for increasing the speed and contrast of such emulsions.

In Trivelli and Smith U. S. application Serial No. 500,088, filed concurrently herewith, a method is described for increasing thespeed or contrast of gelatino-silver halide emulsions. This method involves the incorporationof 'hydrazine or-its derivatives such as hydrazides or semi-carbazides in emulsions to efiect an improvement in the sensitivity characteristics of the emulsion. The Trivelli and Smith application describes hydrazine derivatives of the general formula:

be used in conjunction with the hydrazine compounds of the Trivelli and Smith application to yield marked increases in the efiects obtained with the hydrazine compounds. These added compounds are cationic, onium compounds including cationic cyclammonium quaternarysalts or sulfonium salts which do not act as-desensitizers for the emulsion.

The cationic cyclammonium quaternary salts or sulfonium salts are used together with the hydrazine compound either in the emulsion or the developer. Both the hydrazine compound and. the quaternary salt or sulfoniurn salt may be in the emulsion or both may be in the developer or one may be in the emulsion and the other in the developer.

The following compounds are representative of cationic cyclammonium quaternary salts or sulfonium salts which are suitable for use according to our invention: i 1

BASIC OPTICAL SENSITIZING DYES =Cyanz'ne dyes 3,3-diethylthiazolinocarbocyanine iodide (Brooker, U. S. Patent 3,3 -diethyl-Q-methylselenacaabgrgggiiine iodide (White, U. S. Patent 3,3-diethyloxacarbocyanine iodide (Hamer, J. Chem. 800., 1927,

page 2796) O=GH l C2115 C2115 I V 3,3'-diethyloxacyanine iodide (Fisher & Hamer, J. Chem. Soc., 1934, 40 I page 962) v 0 I s \OH GZCHTO 21.201143 icH 3 N N 32115 C2/H5\I 3,3-diethyl-4-methyloxathiazol0carbocyanine iodide (Mees, U. S. Patent 2,159,565)

ammo

3,8 -dimethyl-9 ethyl 4,5,4 ,5 dilaenzothiacarbobyanine bromide (Brooker, U. S. Patent 1,969,444)

1,1-di methyl-9-aza-2,2-cyanine iodide (Mees, The Theory of the Photographic Process, 1942, page 1025) 3,3-diethyl-4,5,4,5-dibenzothiacyanine iodide (British Patent 504,821)

3,3 diethylthiacarbocyanine iodide (Harr er, J. Chem. Soc, 1927, page 2796) 3,3'-diethyl-9-methylthiacarbocyanine iodide (Homer, J. Chem. 800., 1928, page 3160) N C2115 211s 1,1-diethy1-2,2-cyanine iodide (Mees, The Theory of the Photographic Process, 1942,. page 1002) Pyrrole dyes Styryl dyes NON-SENSITIZING QUATERNARY SALrs CuHa-CH2(3H2 Bl fl-Phenylethyl-a-picolinium bromide CeHsCH2CH2 I fl-Phenylcthyl-a-picoliniumiodide p-Tert. butyl phenoxyethoxy-ethylpyridinium perchlorate C104 CHz-O-CHaCHrO-CH: C104 N,N"ethylene-dioxymethyl pyridinium perchlorate SULFONIUM SALTS CH3 CvHn N onyl dimethyl sulionium p-toluene sulfonate The pyrrole dyes are described in Brooker and Sprague U. S. Patent 2,298,731. The non-sensitizing quaternary salts are referred to in Carroll U. S. Patent 2,271,623 and Carroll and Spence U. S. 2,334,864.

It will be seen that the compounds suitable for use according to our invention include cyclammonium quaternary salts of the sensitizing and non-sensitizing types. All of thes compounds are of the cationic type, that is, possess a complex cationic structure. In the case of the optical sensitizers, the efiect which is produced according to our invention is separate and independent from optical sensitization as will be shown in the specific examples below.

The mechanism of the action of the cationic quaternary salts appears to rest on the adsorption of the positive charges of the cationic agents to the negatively charged silver halide grain with resultant reduction of the induction period during development with negatively charged developer ions. Such induction effects are especially prominent with alkaline p-hydroquinone developers.

Our invention will now be illustrated by reference tov the following specific examples:

EXAMPLE 1,

A fine-grain gelatino-silver bromoiodide emulsion was prepared and to portions of the emulsion were added hydrazine dihydrochloride and 3,3 diethylthiazolinocarbocyanine iodide, sepa rately and in combination. Coatings wer made of these emulsions and, after drying, these coatings were exposed ona photographic sensitometer to the light transmitted from a 3200? K. tungsten source by a Wratten No. 35 filters The. first: of

gamma thesecoating's was the plain emulsion without additions; the second coating contained 4 grams of hy- -'drazine dihydrochloride 'per 4000 cc. of wet emulsi'oni thethird coating consisted of the original emulsion with 100 mg. of '3,3'-diethy'lthiazolinocarbocyanine iodide and the fourth coating consisted of the original emulsion with 4 grams of hydrazine dihydrochloride and 100 mg. of 3,3- diethylthiazolino car-bocyanine iodide added per 4000 cc. of Wet emulsion.

Since the carbocyanine dye added to the third and fourth coatings sensitizes to green light, all of the coatings were exposed through a Wratten No. 35 filter, which absorbs green light, in order to test the efiect of the sensitizing dye on the emulsion independently of its optical sensitizing effect. The filter limited the exposure of all of the emulsions to the blue spectral region.

All of the coatings were processed after exposure for 1.5 minutes at 65 F. in a developer known as Kodak D-8 developer which has the following composition: j

Hydroquinone grams 45 Sodium hydroxide do 27.5 Sodium sulfite (desiccated) do 90 Potassium bromide do Water to iiters 1 The speed and contrast of each of the images was then determined and the following results were obtained.

emulsion was prepared and. to portions of its were added separately and in combination, 4-(o-to1yl) semicarbazide and 3,3-diethylthiazolinocarbo cyanine iodide. These portions were then coated and dried. The first coating consisted of the plain emulsion without additions; the second coating the emulsion to which had been added 100 mg. of l-(o-tolyl) -semicarbazide per 200cc. of wet emulsion; the third coating the original emulsion to which har been added 5 mg. of 3,3-

diethylthiazolinocarbocyanine iodide per 200 cc. of wet emulsion and the fourth coating the orgiinal emulsion to which'had been added 100 mg. of 4-(o-tolyl) -semicarbazide and 5 mg. of 3,3'-diethylthiazolinocarbocyanine iodide per 200 cc. of wet emulsion. These emulsions were exposed through a Wratten No. filter as in the case of Example 1 and were developed in the same manner. The following results were obtained:

g Contrast Fog Emulsion without additions 2.28 4.9 0.05 Emulsion-H00 mg. 4-(otolyl)-semicarbazide 1.95' 6.8 .05 Emulsion+5 mg. 3,3-diethylthiazolmo carbocyanine iodide 2. 22 4. 2 .04 Emulsion+l00 mg. 4-(O-tolyD-sem1carbazide and 5 mg. 3,3-diethylth1azolmocarbocyanine iodide 2. 82 23. 0 07 V] I EXAMPLE3 H A fine-grain gelatino-silver chlorobromide emulsion was prepared and to portions of it were added 4-(o-tolyl) -semicarbazide and a mixture of the semicarbazide and fi-phenylethyl-a-picolini um bromide.

The first portion consisted of the plain emulsion without additions, the second portion consisted. of the original emulsion to which had been added mg. of 4-(o-tolyl) -semicarbazide per 200 cc. of wet emulsion and the third portion consisted of the original emulsion to which had been added 100mg. of 4-(o-tolyl)- semicarbazide and 200 mg. of B-phenylethyl picolinium bromide per 200 cc. of wet emulsion. These three portions were separately coated "and dried-and exposed on a photographic sensitometertolight transmitted from a 3200" K. tungsten source. The Wratten filter was omitted because the quaternary salt used in this case was not an optical sensitizer. The emulsions were processed as in Example 1 and the following results were obtained: r r

ggg Contrast Fog Emulsion without additions 5.35 5. 9 0. 05 Emulsion+l00 mg. 4-(o-toIyD-Semicarbazide 5.10 6.1 .05 Emulsion+l00 mg. 4-(o-toly1)-semicarbazide and 200 mg. B-phenylethyl.-i-

plcolinium bromide 6.45 10.6 .09

EXAMPLE 4 A fine-grain gelatinoesilver chlorobromide emulsionwas prepared and to portions of it were added phenylmethyl-dimethylacethydrazido ammonium chloride and a mixture of the hydrazide and 3,3-diethyl-9-methylthiacarbocyanine iodide; The first portion consisted of'the plain emulsion without additions, the second portion consisted of the original emulsion to which had been added 200 milligrams of phenylmethyl-dimethylacethydrazido ammonium chloride per 200 cc. of wet emulsion and the third portion consisted of the original emulsion to which had been added 200 milligrams of the hydrazide and 5 milligrams of 3,3'-diethyl-9-methylthiacarbo cyanine iodide per 200 cc. of wet emulsion. These three portions were separately coated and dried and exposed on a photographic sensitometer to light transmitted from a 3200 K. tungsten source through a Wratten No. 35 filter. These emulsions were developed as in the case of Example 1 and the following results were obtained:

ag Contrast Fog Emulsion without additions 6.05 5.5 0.07 Emulsion+200 mg. phenyl-methyldimethylacethydrazido ammonium chloride. as. 70 8. 5 06 Emuls1on+200 mg. phenyl-methyldimethylacethydrazido ammonium 'chloride and 5 mg. 3,3-diethyl9-methyl thiacarbocyanine iodide 9.00 13.3 07

.ylthiacarbocyanine iodide :per. 200cc.v of,-wet Y emulsion. Upon exposure and development as in Example 4, the following results were obtained:

EXAMPLE 6 Three emulsion coatings were prepared as in Example 4, thefirst being the emulsion without additions, the second containing 20 milligrams of phenyl succinic dihydrazide per 200 cc. of wet emulsion and the third containing 20 milligrams of phenyl succinie dihydrazide and 8 milligrams of 3,3'-diethylthiazolino carbocyanine iodide per 200.00. of wet emulsion. These coatings were exposed and developed as in Example 4 and the following results were obtained:

lO/i speed Contrast Fo Emulsion without additions 1.62 i. 4 0. 06 Emulsion-[40 mg. plienyl succinic dihydrazide 2. 05 6. 07 Emulsion+20 mg. phenyl succinic dihydrazide and 8 milligrams 3,3-diethylthiazolino-carbocyanine iodide 2. 00 7. 5 .06

r the emulsion.

.sensitometer.

EXAMPLE 7 The following example serves to illustrate'the action of the cyclammonium quaternary salt in the developer with the hydrazine compoundin To a fine grain gelatino-silver chlorobromide emulsion there was addedll.5 grams per 4000 cc.

of 4-(o-tolyl) semicarbazide.

This emulsion was coated and dried and portions of the coating were exposed for one second to a 3000 K. light source on .a photographic The separation portions of the coatings were then developed for two minutes at 65 F. in Kodak D-8 developer oflthe formula stated in Example 1, both without and with addition of varying amounts of 3,3-diethylthiazolinocarbocyanine iodide. The amount of this quaternary salt was varied between 8.3 mg. and 33.3 mg.-per liter of developer and the following sensitometric results were obtained:

Amount of quaternary salt gg Contrast Fog 13.0 6. 0 0.05 8 3 mg. per liter 14.0 6. 0 05 16.7 mg. per liter 16.0 9. 8 .05 33.3 mg. per liter l7. 5 l0. 0 .05

EXAMPLE 8 grams of hydrazine dihydrochloride per liter of D-B developer; the second developer contained 10 milligrams of hydrazine dihydrochloride and 16 zmilligrams of 3,3-diethylthiazolinocarbocyanine iodide per liter of 13-8 developer and the third developer contained 10 milligrams of hydrazine dihydrochloride and 33 milligrams of 3,3- diethylthiazolinocarbocyanine iodide per liter of 13-8 developer. The following sensitometric results were recorded with the various developers.

'g Contrast Fog D-B 2. 60 4.8 0.14 D8+l0 mg. hydrazine dihydrochloride per 1000 cc 3. 60 9.0 .16 D8+l0 mg. hydrazine dihydrochloride+ 16 mg. 3,3-diethylthiazolinocarbocyanine iodide/1000 cc 3. 10.4 l6 D-8+10 mg. hydrazine dihydrochloride+ 33 mg. 3,3-diethylthiazolinocarbocysnine iodide/1000 cc 9. 10 15. 5 25 The acid optical sensitizing dyes such as erythrosine and the neutral optical sensitizers such as the merocyanines either cause-losses in the elfects produced by the hydrazine compounds or are inert sensitometrically from this standpoint. Accordingly, only the basic optical sensitizing dyes are suitable for use according to our invention.

The compounds which are used according to our invention should not desensitize thev emulsion. Certain basic dyes are desensitizers and, therefore, are not satisfactory for use according to our invention. Phenosafranine, for example, is a basic dye which is a well known dessensitizer. Although it might be classed as an optical sensitizing dye, it is better known for its desensitizing properties and is therefore, excluded from the scope of our invention. The structural distinction between those basic dyes which sensitize a photographic emulsion and those which desensitize an emulsion is described by Mees in The Theory of the Photographic Process, 1942, pages 10401047.

The non-sensitizing quaternary salts such as p-phenyl-ethyl-a-picolinium bromide, which are listed above, have been used as supersensitizers in silver halide emulsions. However, our eifect is not believed to be a supersensitization since not all supersensitizers enhance the eifect produced by the hydrazine compounds. For example, 6-methoxyquinoline has been used as a supersonsitizer but is inert with respect to improvement of the sensitometric characteristics in the manner contemplated by our invention.

The eifect produced according to our invention' is noticeable on various types of silver halide emulsions such as silver bromide, silver chlorobromide and silver bromoiodide emulsions.

We have referred to thesensitivity characteristics of the emulsion. By sensitivity characteristics we mean the speed and contrast characteristics as indicated by the characteristic curve of the emulsion.

Where we refer to actinic radiation we intend to include visible light, as well as ultra-violet light, infra-red light, X-rays, and gamma rays, and also charged particles, such as a-rays, ,e-rays, and cosmic rays.

We claim:

1. The method of producing an image inan undeveloped silver halide developing-out emulsion, which comprises exposing said emulsion and developing it with a hydroquinone developing "agent at a pH of at least approximately 9.5 in

the presence of a compound selected from the group consisting of hydrazine compounds of the general formula:

where at least two Rs are hydrogen atoms and when less than 4 Rs are hydrogen atoms the remainder are carbon radicals, and the salts of said compounds, and also in the presence of an onium compound selected from the group consisting of non-desensitizing cationic cyclammonium quaternary salts and sulfonium salts.

, 2. The method of improving the sensitivity characteristics with respect to actinic radiation of a silver halide photographic layer, which comprises exposing an undeveloped silver halide emulsion layer to actinic radiation and developing it with a hydroquinone developing agent at a pH of at least approximately 9.5 in the presence of a compound selected from the group consisting of hydrazine compounds of the general formula:

where at least two He are hydrogen atoms and when less than 4 Rs are hydrogen atoms the remainder are carbon radicals, and the salts of said compounds, and also in the presence of an onium compound selected from the group consisting of non-desensitizing cationic cyclammonium quaternary salts and sulfonium salts.

3. The method of improving the sensitivity characteristics with respect to actinic radiation of a silver halide photographic layer, which comprises exposing an undeveloped silver halide emulsion layer to actinic radiation and developing it with a hydroquinone developing agent at a pH of at least approximately 9.5 in the presence of a compound selected from the group consisting of hydrazine compounds of the general formula:

where at least two Rs are hydrogen atoms and when less than 4 Rs are hydrogen atoms the remainder are carbon radicals, and the salts of said compounds and also in the presence of a non-desensitizing cationic cyclammonium quaternary salt.

4. The method of improving the sensitivity characteristics with respect to actim'c radiation of a silver halide photographic layer, which comprises exposing an undeveloped silver halide emulsion layer to actinic radiation and developing it with a hydroquinone developing agent at a pH of at least approximately 9.5 in the presence of a compound selected from the group consisting of hydrazine compounds of the general formula:

where at least two Rs are hydrogen atoms and when less than 4 Rs are hydrogen atoms the remainder are carbon radicals, and the salts of said compounds, and also in the presence oi a emulsion layer to actinic radiation and developing it with a hydroquinone developing agent at a pH of at least approximately 9.5 in the presence of a compound selected from the group consisting of hydrazine compounds of the general-formula:

NHz NH-R where R is selected from the class consisting of hydrogen andCONHCeH5, and the salts of said compounds, and also in the presence of a nondesensitizing cationic cyclammonium quaternary salt.

6. The method of improving the sensitivity characteristics with respect to actinic radiation of a silver halide photographic layer, which comprises incorporating in a gelatino-silver halide emulsion a hydrazine and an onium compound selected from the group consisting of nondesensitizing cationic cyclammonium quaternary salts and sulfonium salts, coating the emulsion on a support, exposing the emulsion to actinic radiation, and developing it at a pH of at least approximately 9.5 in the presence of said hydrazine and onium compound.

7. The method of improving the sensitivity characteristics with respect to actinic radiation of a silver halide photographic layer, which'comprises incorporating in a gelatino-silver halide emulsion a hydrazine and a non-desensitizing cationic cyclammonium quaternary salt, coating the emulsion on a support, exposing the emulsion to actinic radiation, and developing it at a pH of at least approximately 9.5 in the presence of said hydrazine and quaternary salt.

8. The method of improving the sensitivity characteristics with respect to actinic radiation of a silver halide photographic layer, which comprises exposing said layer to such radiation and developing it at a pH of at least approximately 9.5 in a solution containing a photographic developing agent, a hydrazine compound selected from a group consisting of compounds of the general formula:

tion, and developing it at a pH of at least 9.5 in

a developing solution containing a photographic developing agent and an onium compound selected from the group consisting of non-desensitizing cationic cyclammonium quaternary salts and sulfonium salts.

WlLLIAM F. SMITH. ROBERT E. STAUFFER.