US3598599A

US3598599A - Polymeric thiazole fog stabilizers for photographic emulsions

Info

Publication number: US3598599A
Application number: US673922A
Authority: US
Inventors: Richard C Tuites; Louis M Minsk
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1967-10-09
Filing date: 1967-10-09
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10
Also published as: BE721963A; FR1604619A; GB1246311A

Abstract

POLYMER THIAZOLES CONTAINING THIAZOLE GROUPS EITHER INCORPORATED INTO THE POLYMER CHAIN OR APPENDED TO THE POLYMER BACKBONE AND PHOTOGRAPHIC SILVER HALIDE EMULSIONS OR PHOTOGRAPHIC ELEMENTS CONTAINING FOG-STABILIZING AMOUNTS OF SUCH POLYMERIC THIAZOLES.

Description

United States Patent 01 ace US. Cl. 96-109 19 Claims ABSTRACT OF THE DISCLOSURE Polymeric thiazoles containing thiazole groups either incorporated into the polymer chain or appended to the polymer backbone and photographic silver halide emulsions or photographic elements containing fog-stabilizing amounts of such polymeric thiazoles.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to new polymers which are useful as improved antifoggants and stabilizers for photographic elements and to photographic silver halide emulsions containing such polymers as antifoggants and stabilizers therein.

Description of the prior art During development of a silver halide emulsion, small amounts of silver halide are reduced to metallic silver regardless of whether or not they have been exposed. This reduction of silver ion produces a background fog which is more specifically referred to as chemical fog.

Chemical fog, apparent in most silver halide systems, has been reduced by prior art methods of processing exposed silver halide material in the presence of compounds which restrict development of unexposed silver halide. Such compounds can be incorporated in the silver halide emulsion or in the processing solutions for developing such silver halide emulsions. Compounds which have been found to have a chemical fog inhibiting effect on emulsions which have been subjected to high temperature and high humidity conditions are referred to as emulsion stabilizers. On the other hand, compounds which have been found to have chemical fog inhibiting elfects on emulsions which have not been exposed to adverse storage conditions are referred to as antifoggants. Although a large number of emulsion stabilizers and antifoggants have been used in the prior art, many of these compounds cause undesirable losses in emulsion speed and contrast and others lack adequate compatibility with emulsion gelatin.

SUMMARY OF THE INVENTION According to one embodiment of this invention, there is provided a new class of polymers which are particularly useful as photographic antifoggants and stabilizers. These new polymers contain recurring groups having the formula wherein y is or 1, the radical A is S or NH- and X is a thiazole group. The thiazole groups constitute at least 30% by weight of the polymer and are monovalent when appended to the polymeric backbone and divalent when incorporated into the polymeric backbone.

According to another embodiment of this invention, there is incorporated into the silver halide emulsion of a photographic element or in a layer contiguous to the silver halide emulsion, a fog-stabilizing amount of a poly- 3,598,599 Patented Aug. 10, 1971 mer containing recurring thiazole groups. The polymer stabilizes the emulsion against fog when the dried emulsion has been subjected to a prolonged high humidity and temperature incubation period without adversely affecting other sensitometric properties. It is an advantage of high molecular weight materials, e.g., polymers, that they remain relatively immobile when incorporated into particular layers of a photographic element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One preferred group of polymers in accordance with this invention have the thiazole group incorporated into the polymer chain or backbone. These polymers contain repeating segments having the formula wherein z is an integer of 3 to 8, and R is selected from the group consisting of hydrogen atoms, alkyl (e.g., methyl, ethyl, butyl), and phenyl radicals. Such polymers can be prepared by reacting a diaminothiazole with a dicarboxylic dihalide in an inert solvent.

Another preferred group of polymers have the thiazole groups appended to the polymeric backbone. These polymers contain repeating segments having the formula and radicals; and each R is selected from the group consisting of hydroxy radicals and thioazolyl radicals having the formulae:

at least 25 percent of the total R radicals being said thiazolyl radicals. Such polymers can be prepared by reacting a thiazole which is substituted with a functional group, such as an amino or sulfhydryl group, with a polymer containing reactive groups such as anhydride or ester groups. The reaction can be conducted in the presence of sodium carbonate or sodium hydroxide. When the intermediate polymer is one which contains anhydride groups, such as copoly(styrene-maleic anhydride) or poly(arcylic anhydride), at least half of the A R groups in the above formula will be carboxy radicals. Intermediate polymers having intrinsic viscositties of up to about 1.5 are preferred.

The polymeric thiazoles of this invention can be incorporated into a silver halide emulsion of a photographic element or in a layer contiguous to the silver halide emulsion in any amount which will stabilize the silver halide emulsion against fog. In general, a concentration of the polymeric thiazole in an amount of from about 0.10 to about 50.0, preferably about 0.12 to about 19.0 grams per mole of silver in the silver halide emulsion can be used with good results.

The preparation of photographic silver halide emulsions such as are suitably stabilized with a polymeric thiazole typically involves three separate operations: (1) emulsification and digestion of silver halide, (2) the freeing of the emulsion of excess water-soluble salts, suitably by washing with water, and (3) the second digestion or after-ripening to obtain increased emulsion speed or sensitivity. (Mees, The Theory of the Photographic Process, 1954.) The polymeric thiazole can be added to the emulsion before the final digestion or after-ripening or it can be added immediately prior to the coating.

The silver halide emulsion of a photographic element containing the antifoggants of this invention can contain conventional addenda such as gelatin plasticizers, coating aids, and hardeners such as aldehyde hardeners, e.g., form aldehyde, mucochloric acid, glutaraldehyde bis(sodium bisulfite), maleic dialdehyde, aziridines, dioxane derivatives and oxypolysaccharides. Spectral sensitizers which can be used are the cyanines, merocyanines, complex (trinuclear) cyanines, complex (trinuclear) merocyanines, styryls, and hemicyanines. Sensitizing dyes useful in sensitizing such emulsions are described, for example, in U.S. Pats. 2,526,632 of Brooker and White issued Oct. 24, 1950, and 2,503,776 of Sprague issued Apr. 11, 1950. Developing agents can also be incorporated into the silver halide emulsion if desired or can be contained in a con tiguous layer. Various silver salts can be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide. The silver halides used can be those which form latent images predominantly on the surface of the silver halide grains or those which form latent images inside the silver halide crystals such as described in US. Pat. 2,592,250 of Davey and Knott issued Apr. 8, 1952.

The silver halide emulsion layer of a photographic element containing the antifoggants of the invention can contain any of the hydrophilic, water-permeable hiding materials suitable for this purpose. Suitable materials include gelatin, colloidal albumin, polyvinyl compounds, celluose derivatives, acrylamide polymers, etc. Mixtures of these binding agents can also be used. The binding agents for the emulsion layer of the photographic element can also contain dispersed polymerized vinyl compounds. Such compounds are disclosed, for example, in US. Pats. 3,142,568 of Nottorf issued July 28, 1964; 3,193,386 of White issued July 6, 1965; 3,062,674 of Houck, Smith and Yudelson issued Nov. 6, 1962; and

4 3,220,844 of Houck, Smith and Yudelson issued Nov. 30, 1965; and include the water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The silver halide emulsion of a photographic element containing the antifoggants of the invention can be coated on a wide variety of supports. Typical supports are cellulose nitrate film, cellulose ester film, polyvinyl acetal film, polystyrene film, poly (ethylene terephthalate) film and related films or resinous materials as well as glass, paper, metal and the like. Supports such as paper which are coated with a-olefin polymers, particularly polymers of a-olefins containing two or more carbon atoms, as exemplified by polyethylene, polypropylene, ethylene butene copolymers and the like can also be employed.

The speed of the photographic emulsions containing the antifoggants of the invention can be further enhanced by including in the emulsions a variety of hydrophilic colloids such as carboxymethyl protein of the type described in US. Pat. 3,011,890 of Gates, Jr., Miller and Koller issued Dec. 5, 1961, and polysaccharides of the type described in Canadian Pat. 635,206 of Koller and Russell issued Jan. 23, 1962.

Photographic emulsions containing the antifoggants of the invention can also contain speed-increasing compounds such as quaternary ammonium compounds, polyethylene glycols .or thioethers.

Photographic elements containing the antifoggants of the instant invention can be used in various kinds of photographic systems. In addition to being useful in X-ray and other non-optically sensitized systems, they can also be used in orthochromatic, panchromatic and infrared sensitive systems. The sensitizing addenda can be added to photographic systems before or after any sensitizing dyes which are used.

Silver halide emulsions containing the antifoggants of the invention can be used in color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type such as described in US. Pat. 2,698,794 of Godowsky issued Jan. 4, 1955; in silver dye-bleach systems; and emulsions of the mixed-grain type such as described in US. Pat. 2,592,243 of Carroll and Hanson issued Apr. 8, 1952.

Silver halide emulsions containing the antifoggants of the invention can be sensitized using any of the wellknown techniques in emulsion making, for example, by digesting with naturally active gelatin or various sulfur, selenium, tellurium compounds and/ or gold compounds. The emulsions can also be sensitized with salts of noble metals of Group VIII of the Periodic Table which have an atomic weight greater than 100.

Silver halide emulsions containing the antifoggants of the invention can be used in diffusion transfer processes which utilize the undeveloped silver halide in non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a silver layer in close proximity to the original silver halide emulsion layer. Such processes are described in US. Pats. 2,352,014 of Rott issued June 20, 1944; 2,543,181 of Land issued Feb. 27, 1951; and 3,020,155 of Yackel, Yutzy, Foster and Rasch issued Feb. 6, 1962. The emulsions can also be used in diffusion transfer color processes which utilize a diffusion transfer of an imagewise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Silver halide emulsions containing the antifoggants of the invention can be processed in stabilization processes. such as the ones described in US. Pat. 2,614,927 of Broughton and Woodward issued Oct. 21, 1952, and as described in the article Stabilization Processing of Films and Papers by H. D. Russell, E. C. Yackel and I. S. Bruce in P.S.A. Journal, Photographic Science and Technique, Volume 16B, October 1950.

The antifogging agents of this invention can be incorporated to advantage during manufacture in silver halide emulsions representing the variations described above. Moreover, fog control in binderless silver halide films prepared by vapor deposition of silver halide on a suitable support can be achieved by coating the antifogging agents of the invention over the vapor deposited layer of silver halide.

Combinations of all the above-mentioned addenda can be used if desired.

The following examples illustrate the best modes contemplated for carrying out this invention; although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.

EXAMPLE 1 To a mixture of 2,4-diamino-5-phenylthiazole monohydrobromide (25.5 grams, 0.094 mole) and triethylamine (31 grams, 0.307 mole) in 200 milliliters of dimethylformamide is added in one portion adipyl chloride (17.2 grams, 0.094 mole) with rapid stirring under nitrogen at room temperature. The reaction is allowed to run under ambient conditions for 24 hours. The product is precipitated by pouring the reaction mixture into 2-3 liters of water with stirring. The product is filtered, washed aagin with water, and dried in a vacuum oven at 40 C. overnight. Yield of light yellow solid is 20.5 grams.

Analysis.-Found (percent): C, 58.0; H, 5.2; N, 14.0; S, 11.8; CI, 0.5.

The inherent viscosity in dimethylformamide is 0.06. The product consists essentially of repeating segments having the formula The product is dissolved in dimethylformamide/water (2/1), pH adjusted to 6.3 with percent sodium hydroxide, and subjected to photographic testing as described hereinafter.

EXAMPLE 2 To a solution of copoly(ethylene-maleic anhydride) having an inherent viscosity in dimethylformamide of 0.82 (12.6 grams, 0.1 mole) in 200 milliliters of dimethylformamide is added 2-aminobenzothiazole (15.0 grams, 0.1 mole). The reaction mixture is stirred under nitrogen for 4 hours at 75 C. The entire content is poured into 2-3 liters of diethyl ether with stirring. The supernatant ether is decanted and the precipitate is washed with water and dried in a vacuum oven at 40 C. overnight. The yield of light tan solid is 22.5 grams. After drying, the product is again washed with water, followed by ether and re-dried. The final yield of light tan solid is 16 grams.

Analysis-Found (percent): C, 54.0; H, 4.8; N, 6.2; S, 6.8. The analytical results for nitrogen and sulfur are consistent with the product containing about 60 percent of the theoretical amount of the benzothiazole system off the polymer chain. The product contains repeating segments having the formula The product is suspended in water and dissolved by adding 10 percent sodium hydroxide. The solution, pH: 6.2, 1s subjected to photographic testing as hereinafter described.

EXAMPLE 3 The process of Example 2 is repeated substituting for the copoly(ethylene-maleic anhydride) an equimolar amount of poly(acrylic anhydride) having an inherent viscosity in dimethylformamide of 0.31. The product contains recurring segments having the formulae and l j S i m HN wherein the ratio of the values of m to n is about 5:3. Analysis of the product for nitrogen and sulfur indicates that the product contains about percent of the theoretical amount of benzothiazole groups off the polymer chain.

EXAMPLE 4 Analysis of the product for nitrogen and sulfur indicates that the product contains about percent of the theoretical amount of 2-mercapto-6-aminobenzothiazole groups off the polymer chain.

EXAMPLE 5 The process of Example 3 is repeated substituting for the 2-aminobenzothiazole an equimolar amount of 2- mercapto-6-aminobenzothiazole and using a poly(acrylic anhydride) having an inherent viscosity in dimethylformamide of 0.79. The product contains recurring segments having the formulae wherein the ratio of the values of m and n is about 2:1. Analysis of the product for nitrogen and sulfur indicates that the product contains about 70 percent of the theoretical amount of Z-mercapto-6-aminobenzothiazole groups off the polymer chain.

EXAMPLE 6 The process of Example 3 is repeated substituting for the Z-aminobenzothiazole an equimolar amount of 2- aminothiazole and using a poly(acrylic anhydride) having an inherent viscosity in dimethylformamide of 0.23. The product contains recurring segments having the formulae.

and

wherein the ratio of the values of m and n is about 4:3. Analysis of the product for nitrogen and sulfur indicates that the product contains about 85 percent of the theoretical amount of 2-aminothiazole groups off the polymer chain.

7 EXAMPLE 7 The process of Example 6 is repeated substituting for the poly(acrylic anhydride) an equimolar amount of copoly(styrene-maleic anhydride) having an inherent viscosity in dimethylformamide of 1.37. The product contains repeating segments having the formula Analysis of the product for nitrogen and sulfur indicates that the product contains about 82 percent of the theoretical amount of the 2-amin0thiazo1e groups off the polymer chain.

EXAMPLE 8 The process of Eample 2 is repeated substituting for the 2-aminobenzoth'iazole an equimolar amount of 2- amino-4-(4-biphenylyl)triazole. The product contains repeating segments having the formula HO HN Analysis of the product for nitrogen and sulfur indicates that the product contains about 75 percent of the theoretical amount of Z-amino-4-p-diphenylthiazole groups off the polymer chain.

EXAMPLE 9 Vinyl acetate is polymerized in refluxing methanol solution in the presence of an equimolar amount of chloroform using about 3 percent by weight of monomer of 2,2'-azobis(Z-methylpropionitrile) as catalyst. The polymerization is allowed to run for 48 hours at 70 C. under nitrogen. The product is obtained as a tacky, light yellow solid by evaporating oil the solvent and washing the residue with ligroine. The product is further purified by dissolving it in a small volume of acetone and precipitating into ligroine. After drying, the yield of tacky solid is about 4050 percent of the theoretical yield. The inherent viscosity of the product in acetone is 0.13 and the molecular weight is estimated on the basis of chlorine analysis to be between 3000 and 4000. This product is hydrolyzed using sodium hydroxide in methanol to give poly(vinyl alcohol).

Low molecular weight poly(vinyl alcohol) prepared as described above (22 grams, about 0.05 mole) and chloroacetic anhydride (90 grams, 0.525 mole) are heated together in 1000 milliliters of refluxing 1,2-dichloroethane under nitrogen for 4 to hours. The reaction mixture is then poured into 2-3 liters of methanol. The precipitated product is washed with additional methanol and the resulting gummy solid is dried in a vacuum oven overnight. The yield of yellow-tan, flaky solid is 21 grams.

Analysis.Calcd. (percent): Cl, 29.4. Found (percent): CI, 26.3.

The calculated chlorine analysis is for the polymer repeating unit without end-groups. The chlorine analysis indicates about 8590 percent reaction to give the chloroacetate product. Concentration of the mother liquors followed by washing with diethyl ether and reprecipitating from a small amount of acetone with ligroine yielded another 14 grams of gummy product after drying. The product is low molecular weight poly(vinyl chloroacetate).

To a solution of poly(vinyl chloroacetate) prepared as described above (12.0 grams, 0.1 mole) in 200 milliters of dimethylformamide are added Z-mercaptobenzothiazole (16.7 grams, 0.1 mole) and sodium carbonate (5.3 grams, 0.05 mole). The mixture is heated at 70 C.

for 24 hours under nitrogen with stirring. The reaction mixture is poured into 2-3 liters of Water with stirring and filtered. The solid is Washed very well with methanol, filtered, and dried in a vacuum oven at 40 C. overnight. The product, 14 grams, is a light tan solid.

Analysis.Found (percent): C, 52.2; H, 4.5; N, 3.5; S, 18.9; C1, 5.1.

The analytical results for nitrogen and sulfur are consistent with a product containing about 60-70 percent of the theoretical amount of the benzothiazole system off the polymer chain. The product contains repeating segments having the formula The product is dissolved in a 1:1 mixture of dimethylformamide and acetone and the solution is subjected to photographic testing as hereinafter described.

EXAMPLE 1O Polyvinyl alcohol having an inherent viscosity in water of 0.4 is treated with chloroacetic anhydride as described in Example 9 to obtain poly(vinyl chloroacetate) having a chlorine content of 28.0%. The product is then reacted with Z-mercaptobenzothiazole as described in Example 9. Analysis of the product for nitrogen and sulfur indicates that the product contains about 82 percent of the theoretical amount of Z-mercaptobenzothiazole groups ofr th polymer chain. 1

EXAMPLE l1 Z-mercaptobenzothiazole (16.7 grams, 0.1 mole) and sodium hydroxide (4.0 grams, 0.1 mole) are heated in 200 milliliters of dimethylformamide for one hour at 75 C. under nitrogen. Copoly(ethylene-maleic anhydride) having an inherent viscosity in dimethylformamide of 0.13 (12.6 grams, 0.1 mole) is added and the mixture heated at 75 C. for 4 hours under nitrogen. The reaction mixture is poured into 2-3 liters of acetone with stirring. The product is filtered off and dried in a vacuum oven at 40 C. overnight. A purplish solid (15 grams) is obtained. The dry solid is washed very well with methanol and re-dried. Recovery of the product is 13 grams.

Analysis-Found (percent): C, 39.9; H, 4.4; N, 2.1; 2.6; 2.8; S, 2; Na, 11.6.

The nitrogen analysis is consistent with a product containing about 50-60 percent of the theoretical amount of the benzothiazole system off the polymer chain. The product contains repeating segments having the formula The product is dissolved in water and the pH adjusted to 6.4 by the addition of 10 percent aqueous sodium hydroxide. The resulting solution is subjected to photographic testing as described hereinafter.

EXAMPLE 12 The process of Example 11 is repeated substituting for the 2-mercaptobenzothiazole an equimolar amount of 2- rnercapto-6-nitrobenzothiazole. The product contains repeating segments having the formula Analysis of the product for nitrogen and sulfur indicates that the product contains about 25 percent of the theoretical amount of Z-mercapto-6-nitrobenzothiazole groups off the polymer chain.

and is terminated at one end thereof by H and on the other end by the group SCHCH OH.

EXAMPLE 15 EXAMPLE 13 2-aminobenzothiazole (9.0 grams, 0.06 mole) and vinylte (4.15 grams 0.06 mole) are allowed to react Low molecular wer ht ol hen l acr late havin a tsocyana molecular weight of aiapr xiiiia tely 1060 and iermina t ed m 250 mllhhhters. anhydrous dlethyl ether P with Z-mercaptoethanol (14.6 grams, 0.1 mole) is dispefature under [Imogen for hours a i solved in 200 milliliters of distilled N-methylpyrrolidone. minutes after the reactatits are mlxed Whlle begins 2-aminothiazole (18 grams, 0.18 mole) is added and the to separatifronzithz prevlously homogeneous reaptlon i reaction mixture is heated with stirring under nitrogen at i t t 6 en 0 the teale901 penod the .Whlte F 160-170 C. for 24 hours. The reaction medium is homo- Hate 1S filtered wafhed Wlth. ether and The yleld geneous and turns quite dark during the course of the E; mduct ;\I'vmy1 N 'benzothlazol'z'yl urea 18 11 grams t heating period. The product 15 prec1p1tated by pourlng the perceil c reaction mixture into 3 liters of distilled water. The pre- 15 19 ig i l ffg z ffi 5 g cipitate is then washed several times with fresh quantities 3 N o perce of water to allow for removal of any unreacted Z-aminot 'M R t t th thiazole, filtered and dried in a vacuum overnight. The e a spec m are consls cm W 6 yield of tan solid is about 17 grams. 'N 'beniothlazoliz'yl urea structute' Analysis Found (percenty C H N 16 20 N-vmyl-N -benb0th1aZol-2-yl urea 1s polymerized in S 19 4 refluxlng acetone with 1 percent 2,2-azobis-[2-methylpro- The nitrogen and sulfur analyses are consistent with a plomtnle] fatalyst for 24 under. nitrogen T product wherein about 90 percent of the phenyl ester product preclpitates from solutlon as a whlle sol1d during groups have reacted to give the thiazolyl-amide linkage. the course of i heaimg 9 The Infrared .Spectrum of The product is dissolved in dimethylformamide and 25 the pq cqnslstent wlth polymer; Structure tested as an antifoggant as described hereinafter. compnsmg repeating Segments havmg the formula The product contains repeating segments having the formula -CH2CH -CH2?H I N S 1 HN l NH- N and is terminated at one end thereof by H and on the other end thereof by the group SCH CH OH.

EXAMPLE 14 The polymerfis dissolved in dimethylformamide for testn as an anti 0 t. The process of EJFamPIe 13 is repiated usmg poly 4O 1 Each of the c iiiaounds prepared in Examples 1 to 15 5552221122 33? 3.222%: 523E231? 332122.232; 4

b 1 f th than): in 1od1de emuls1on. For purposes of comparison, high speed g m 0 d i a l P. d nd silver br0mo1od1de emuls1ons are also prepared lncoron O h no 13 Preclpl e a poratmg the hydrolysls products of the intermediate polymet anolrat ert g z 5 N 12 8' mers used in Examples 5 and 11 i.e., polyacrylic acid Analyszs.-Found (percent). 5 .3, H, obtained by hydrolysis of the polyacrylic anhydride nitro n and sulfur anal Ses indicate that about having an inherent viscosity in dimethyltormamide of 0.79 85 95 f th h 1 t y h t d t and copoly(ethylene-ma le1c ac1d) obta1ned by hydrolysis hp g a l l Yd r f fgh ave d 6 o ot copoly(ethy1ene-male1c anhydrlde) havmg an inherent f t e 1 lazoy 3 g e Pro uct vlscosity in dimethylformamide of 0.13. Each emulsion tams repeatmg segments havmgt e ormula sample is coated on a cellulose acetate film support at a CH2CH coverage of 459 milligrams of silver and 1040 milligrams of gelatin per square foot. A sample of each film coating is exposed on an intensity scale sensitometer, processed for i five minutes in Kodak Developer DK-SO, fixed, washed and dried. The photographic results obtained from these 5 tests are listed in the table below.

TABLE Incubation at 120 F. and 50% Fresh relative humidity for 2 weeks G. l R l. R 1. Compound of Example l g spee ii Gamma Fog spee d Gamma Fog 100 1.38 0. 11 33 0. s0 0. 74 so 1. 52 0. 10 so 1. 12 0. 20 97 1. 43 0. 14 63 1. 10 0. 29

TABLE Continued Incubation at 120 F. and 50% Fresh relative humidity for 2 weeks G./rnole Rel. Rel.

Compound of Example Ag speed Gamma Fog speed Gamma Fog Polyacrylic acid 18.0 110 1. 65 0. 35. 5 0. 85 1 0. 83 Copoly(ethylene maleic acid) 45. 0 123 1. 62 0. 24 1 1. 0

1 l-week incubation instead of 2-week incubation.

The results in the above table show that the compounds of the invention prevent the growth of incubation fog when incorporated in photographic emulsions but that polymers which do not contain the thiazole nucleus are either inert or cause fog in photographic emulsions.

Although the invention has been described in considerable detail with reference to certain embodiments thereof, it will be understood that variations and modifications can be effected without departing from the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A composition comprising a photographic silver halide emulsion stabilized against fog with a fog-stabilizing amount of a polymeric thiazole containing repeating segments having the formula wherein the thiazole groups consititue at least by weight of said polymeric thiazole.

4. A composition comprising a photographic silver halide emulsion stabilized against fog with a fog-stabilizing amount of a polymeric thiazole containing repeating segments having the formula wherein at is 0 or 1, and when x is 0, R is hydrogen, and when x is 1, R is hydrogen or phenyl; A is selected from the group consisting of radicals; and each R is selected from the group consisting of hydroxy radicals and thiazolyl radicals having the formulae:

\S/ 7:9 are at least 25 percent of the total R radicals being said thiazolyl radicals.

5. A composition as set forth in claim 4 wherein said repeating segments have the formula OH HILJ 6. A composition as set forth in claim 4. wherein said repeating segments have the formula Q) HJKEQQ 7. A composition as set forth in claim 4 wherein said repeating segments have the formula 8. A composition as set forth in claim 4 wherein said repeating segments have the formula 9. A composition as set forth in claim 4 wherein said repeating segments have the formula and wherein the polymer is terminated on one end thereof by H and on the other end thereof by the group SCH CH OH.

10. A composition as set forth in claim 4 wherein said repeating segments have the formula and wherein the polymer is terminated on one end thereof by -H and on the other end thereof by the group SCH CH OH.

11. A photographic element comprising a support coated with a silver halide layer, said element stabilized against fog by a fog-stabilizing amount of a polymeric thiazole containing repeating segments having the formula N -Nn Time (CH1) Pr":-

wherein z is an integer of from 3 to 8, and R is hydrogen, alkyl, or phenyl, and wherein the thiazole groups constitute at least 30% by weight of said polymeric thiazole.

12. A photographic element comprising a support coated with a silver halide layer, said element stabilized against fog by a fog-stabilizing amount of a polymeric thiazole containing repeating segments having the formula wherein the thiazole groups constitute at least 30% by weight of said polymeric thiazole.

13'. A photographic element comprising a support coated with a silver halide emulsion, said element stabilized against fog by a fog-stabilizing amount of a polymeric thiazole containing repeating segments having the formulae at least 25 percent of the total R radicals being said thiazolyl radicals.

14. A photographic element as set forth in claim 13, wherein said repeating segments have the formula DE EN 15. A photographic element as set forth in claim 13, wherein said repeating segments have the formula -CH2CHCHCH2 8 H0 HN- 16. A photographic element as set forth in claim 13,

wherein said repeating segments have the formula CHzCHCHCHz 17. A photographic element as set forth in claim 13, wherein said repeating segments have the formula I l S 6 NO2 s 18. A photographic element as set forth in claim 13, wherein said repeating segments have the formula CHzCH no N Hl and wherein the polymer is terminated on one end thereof by -H and on the other end thereof by the group SCH CH OH.

19. A photographic element as set forth in claim 13, wherein said repeating segments have the formula and wherein the polymer is terminated on one end thereof by H and on the other end thereof by the group -SCH CH OH.

US. Cl. X.R. 96-114