US2955036A

US2955036A - Fog reduction in photographic silver halide emulsions

Info

Publication number: US2955036A
Application number: US730794A
Authority: US
Inventors: Dersch Fritz; Angelus Millet R De
Original assignee: General Aniline and Film Corp
Current assignee: GAF Chemicals Corp
Priority date: 1958-04-25
Filing date: 1958-04-25
Publication date: 1960-10-04
Anticipated expiration: 1977-10-04

Description

h the like; aryl such as phenyl, toluyl, naphthyl, and the formula which we have foundto be eflfective are:

United States lC Patented och 1,

S-(p-carboxyethyl)-cysteine and its sodium, potassium;

ammonium, silver or amine salt.

2,955,036 7 S-(v-carboxypropyl)-cysteine and the methyl, ethyl or Q phenyl esters thereof. o FOG XE EE E &%%% SILVER S-carboxymethyl-cysteine hydrochloride Fritz Dersch and Millet R. De Angelus, Binghamton, B50200C'?H'GHZ SCHPOQOCZHE N.Y., assignors to General Aniline & Film Corpora- NH, 7 New York a corporation of D elaware S-carbethoxymethyl-cysteine ethyl ester No Drawing. Filed Apr. 25, 1958, Ser. No. 730,794 7 S-(p-carbethoxymethyl)-cysteine ethyl ester "8 Claims. (Cl. 96-66) 10 nooc cncnvs cnrooon NHO C-C5H5 N-benzoyl-S-carboxymethyl-cysteine use of antifo in J The present invention relates to the g g H3O QOO CHGHZ S CHQ C O 0 CH3 and stabilizing agents for photographic silver halide emulsions and, more particularly, to the employment of NHQQCGHE I s carboxy-alkyl-cysteines, their salts and esters for such benzoyl cai-homethoxymethyhoysteiho m h l P P ester. -It is recognized that'light sensitive emulsions such as N benzoyl s oarboethoxymethyhoysteiho ethyl ester} gelatino silver halide emulsions have a tendency to fog. 2o N aoetyhgoarhothoxymothyhoystoiiie h l ester, 7 The feg may be caused in a number of Ways for The above compounds are best prepared by reacting in: mpl y excessive r p g of the emulsion, y Storage aqueous solution and in a mildly alkaline mediunif of the light sensitive element at elevated temperatures and 9 cysteine h d hl id i h a h l humidity, y Prolonged development f the exposed aliphatic acid such as chloroacetic acid, bromoacetic acid, emulsiohiodoacetic acid, B-bromopropionic acid or 'y-bromobutyric A great number 0 ahtifeggihg and Stabilizing agents acid in the presence of an acid binding agent such.as have been recommended in the literature for the purpose sodium hydroxide, potassium hydroxide or h hk Aft 0f. Preventing the formation of fog in light sensitive standing for several hours, the S-carboxyalkyl-cysteine Silver halide emhleions- Although these compounds have precipitates from the reaction mixture. Alternatively, the the ability to control fog during manufacture, as well as s ik li c l h prepared ng. during Storage, y also have distinct Shortcomings to the procedures described in J. Biol. Chem. Soc., vol; For instance, they lower the sensitivity of the emulsion 106, pages 331.341; J .A C.S., vol. 66, pages 1757-9, and either immediately or under storage conditions, thus caus- 1 Chin Aota, 1 27,. 12304; ihg Speed l'egfession- The S-carboxyalkyl-cysteine thus formed may be conv We have new found that the s-earhexyalkyl-eysteines, verted to its salt by reacting it with a Water soluble their salts and esters are excellent stabilizers and antiaihaii compound containing the d i cation such-as foggants for silver halide emulsions having the ability to potassium b t sodium carbonate, ammonium car: maintain the sensitivity and fog at or close to initial optihohato or the like or with a suitable acid such as hydro, mum values under keeping conditions of high temperature hl i acid, hydrohromio id and the l l and humidity i 40 If the esters are desired, they may be producedinthe use of P compounds to lhhlhlt fog and to conventional manner by refluxing the free acid with the bilize silver halide emulsions either by location of the desired alcohol Such as methyl alcohol, ethyl alcohol, same in the emulsion, in layers adjacent to the emulsion h i l h l or ith a phenol in the presence of hydroor in processing baths for the emulsion constitutes the ohiorio id, Th .diesters. are prepared by reacting Purposes and Objects of the Presehlf ihvehhohcysteine with the ester of a halogen substituted aliphatic The s'carboxy'uower)'alkyhcystelhes, the use of which acid followed by treatment with an alcohol in an 'acid is contemplated herein, may be represented by the folmedium to insure complete t -ifi ti lowlhg formula: Beneficial eifects and fog reduction are obtained Whert R00CGH.OH2S(GH2)..COOR aqueous or alcoholic solutions of the aforementioned NHR1 compounds are incorporated in the silver halide emulsions as ripening finals or as coating finals. Ripening' finals are added during the ripening or the sensitivity increasing stage of the emulsion making process. Such additions may be made before, during or after the decomposition of the soluble silver salt such as silver nitrate bymeans of a soluble halide such as potassium-bromide, sodium chloride or the like in the presence of ja colloidal carrier such as gelatin, PVA, solubilized casein or albumen.

Coating finals are added to the emulsion justlprior. to coating on a suitable support such as glass, paper or film at a time when the emulsion has nearly obtainedits maximum sensitivity. L I When used as ripening finals, the antifoggants are best, BF 6 employed in a concentration of 0.20 to -2.5 milligrams per mol of silver halide and when used as coating finals in a concentration of 0.2 to 10 milligrams per mol ofsilver halide. The concentration used depends on the ammonium saver or orgamc amine salts type of emulsion employed, and it is advisable to de- -CH2SCHrCH2-COOH 7 termine the optimum concentration from case to case, 7 In some instances, it is advantageous to apply theantiwherein R is hydrogen, an aliphatic radical such as lower alkyl, i.e. methyl, ethyl, propyl, butyl, amyl and'the like; hydroxyalkyl, i.e., hydroxymethyl, hydroxyethyl and the like; carboxyalkyl, i.e., carboxymethyl, carboXyethyl and 5 like; aralkyl such as benzyl, phenethyl and thelike; or a salt forming group, i.e., sodium, potassium, ammonium, silver, tr'iethylamine, diethylamine, triethanolamine and the like; R is a hydrogen atom, an acyl radical, i.e., 6o acetyl, proponyl, butyryl, benzoyl, phenacyl, and the like; and n is a whole number of from 1 to 3.

Examples of compounds within the ambit of such a S-carboxymethylcysteine and its sodium, potassium,

foggant and stabilizers in layers adjacent to the emulsion, that is, in a separate undercoating layer or in the anti-abrasion gelatin surface. In other instances, the dsir e' d' res'ult may be obtained addition oil the antifoggant and stabilizer to one or several processingbaths? s'iichas developer, prebathor the like. r

The aforesaid antifoggants and stabilizers may'be. uti lized in connection with any type oiphotographic emulsion, e.g., non-sensitized, orthochromatic, panchromatic, boil type emulsions, ammonia type emulsions, X-ray emulsions, paper emulsions, color emulsions or the like. They may be employedincombinationwith'other known antifoggants and stabilizers, reductionand metal and noble metal sensitizers, or in combination with hydroxypolyethenoxy derivates, i.e., those obtained by reacting ethylene oxide with an alcohol, phenol,. amine or the. like (see US. Patent 1,970,578).

Although our stabilizers are somewhat related to cysteine, cystine and methionine which were previously recommended as emulsion. additives, these compounds provide eve n l'mder optimum conditions only a limited antifogging protection. 'Ihese moderate benefits are accompaniect by a number of undesirable properties, such as reduced sensitivity of. the emulsion and. lowered. contrastv together with increased fog underconditions of. high-temperature storage. The compounds of our inventionare free from these disadvantages.

I The. invention is illustrated by the following examples, limit is to be understood that the invention. is. not restficted thereto.

" Example I A-silver halide emulsion in gelatin containing 4 percent silver iodide and 96 percent silver bromide waspre-- pared in aconventional manner and brought up to its maximumlight sensitivity. It. was then readied for coating, finals were added such as'sensitizingdyes, stabilizers and hardening. agents. A 1 percent solution. of S'-(flcarboxyethyl)-cysteine was added to the emulsion as: an antifoggant. The. emulsion samples. weighed one kilogram and contained about .4 mol of silver halide. The so prepared emulsion samples were coated on a suitable cellulose ester base and dried. Samples of these film: coatings were; then exposed in .a Type: IIB Sensitometer and developed in a developer of the following composi- 4 precipitates were. combined. and purified by recrystallization from water. The product melted at 192 C. The product had the following formula:

HO 0 o-on.onzs-onz-onzo 0 on NH: Ananalysisgavethe following'results:

o i H. N r s 5. be 7. s2 17. 88 5. 24 7- 68 17. 51

Example II The procedure was the same as in Example I except- The procedurewas the same as in Example I except that the S-(fi-carboxyethyl)-cysteine was replaced by an equivalent quantity of N-acetyl-S carbethoxymethyl cysteine ethyl ester. The results were similar to those of Example I. This product was prepared according to the procedure; described in Helv. Chim. Acta, vol. 27, pages 1280-4, 'by reacting cysteine hydrochloride in an alkaline'medium successively with chloroacetic acid and acetic anhydride and esterifying the resultant dicarl'aoxylic acid.

' Example IV The procedure was the same as in Example I except ing that the S -(fi carboxyethyl)cysteine was replaced by an equivalent quantity of. N-acetyLS-(fl-carboxyethyllcysteine; The. results were. similar to those obtained in. Examplel.

Example V The antifogging action of S-(B-carboxyethyl') -cysteine was compared with-that of cysteine and cystine. The following results were obtained.

It is 'evident from this .table that the s-(flrcarboxyv ethyl):-cysteine reduces fog without loss .of speed. to a;

tionz;

p Grams Metol (p-methylaminophenol sulfate) L5 sulfite, anhydrous 45 blSlllfite j Hydroquinone 3: carbonate, monohydrated 6 Potassium bromide 7 0,8 Water to make 1 liter.

V j .Speedi LOven'fQg' Quantltyofflompoundadded Relative Fog at after oven atfiDe- .Speed 6' Dev test velopment- The S-(fl-carboxyethyl)-cysteine was prepared as follows: a I

15.7 grams. cysteine hydrochloride (.0.1' mol) was added to 100-milliliters of 110 N sodium-hydroxide solution and the pH adjusted toa point between 8' andf9. To this dispersion was added a solution of 15.3 grams of j3- bromo-propionic acid in St) milliliters of water whereupon greater extent than the cysteine and the cystine which. in addition .to: their poorer antifogging performance, cause .aserious loss of speed.

Example VI A gelatin solution containing 30 grams of gelatin, 1 0.0 mgLof S'(fi carboxyethyl)cysteine per liter was coated on filmbasein' a manner known to the art. After the coating was performed,.a silver halide emulsion in gelatin containing 4 percent of silver iodide and 9-6 percent of silver bromide was coated on top of the previously coated gelatin layer; After drying, film samples. were exposed and processed as described in Example III. The samplm exhibited a relative speed of and a fog of 0.12 compared with a type coating of the same emulsion having undercoating similar to that described above, but

lacking the antifoggant and having a speed of 100 and a fog of 0.20.

Example VII Exposed samples of a photographic film were developed for twelve minutes at 65 F. in a standard metol-hydroquinone developer. Two tests were made, one with the normal developing solution and one with a developer containing mgs. of S-(B-carboxyethyl)-cysteine per liter of developer. Sensitometric strips, developed in the normal developer (control) for twelve minutes, showed a fog of .30, whereas those strips which were developed in the developer containing the antifoggant had a fog of .20.

Various modifications of the invention will occur to persons skilled in the art. Thus, it is understood that in lieu of using the particular antifoggants of the examples, any of the antifoggants listed in the application may be employed with equivalent results. We, therefore, do not intend to be limited in the patent granted except as necessitated by the prior art and the appended claims.

We claim:

1. A light sensitive photographic material comprising a base and a light sensitive silver halide emulsion, said light sensitive material containing as an antifoggant a compound of the following constitution:

wherein R is selected from the class consisting of hydrogen, and alkyl, hydroxyalkyl, carboxyalkyl, aryl and aralkyl radical and a sodium, potassium, ammonium, silver and an amine cation; R is a member selected from the class consisting of hydrogen and acyl groups wherein the total number of carbon atoms in said radicals and groups does not exceed eight, and n is a whole number ranging from 1 to 3. i

2. The article as defined in claim 1 wherein the antifoggant is located in the silver halide emulsion.

3- T e a s s s in c m 1 w ere t e ant foggant is located in a layer adjacent to said silver halide emulsion layer.

4. A light sensitive photographic material comprising a base with a light sensitive silver halide emulsion thereon, said emulsion containing as an antifoggant the compound S-(fl-carboxye'thyl) -cysteine.

5. A light sensitive photographic material comprising a base with a light sensitive silver halide emulsion thereon, said emulsion containing as an antifoggant the compound S-(carboxymethyl)-cysteine.

*6. The process of minimizing and preventing fog in light sensitive silver halide materials comprising a base having a light sensitive silver halide emulsion thereon, which comprises exposing said emulsion to light and developing the same in the presence of an antifoggant having the following structural formula:

wherein R is selected from the class consisting of hydro gen, an alkyl, hydroxyalkyl, carboxalkyl, aryl and aralkyl radical and a sodium, potassium, ammonium, silver and an amine cation; R is a member selected from the class consisting of hydrogen and acyl groups wherein the total number of carbon atoms in said radicals and groups does not exceed eight; and n is a whole number ranging from 1 to 3.

7. The process as defined in claim 6 wherein the antifoggant is S-(B-carboxyethyl)-cysteine.

8. The process as defined in claim '6 wherein the antifoggant is S-carboxymethyl-cysteine.

References Cited in the file of this patent UNITED STATES PATENTS 2,363,777 Downing et al. Nov. 28, 1944 2,438,716 Mueller Mar. 30, 1948 2,449,153 Urbach Sept. 14, 1948