US3542554A

US3542554A - Mercapto-substituted hydroquinone developing agents

Info

Publication number: US3542554A
Application number: US686823A
Authority: US
Inventors: Truman R Mcmurtray
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1967-11-30
Filing date: 1967-11-30
Publication date: 1970-11-24
Anticipated expiration: 1987-11-24
Also published as: BE724619A; FR1593829A; GB1248218A; DE1811899A1

Description

United States Patent Othce 3,542,554 Patented Nov. 24, 1970 Int. Cl. G03c 5/38 US. Cl. 96--61 13 Claims ABSTRACT OF THE DISCLOSURE Monobaths containing certain mercapto-substituted hydroquinone developing agents and mercaptan stabilizing agents for developing and stabilizing photosensitive elements have improved stability and increased useful processing life.

This invention relates to mercaptan monobath compositions and processes for the development of silver images in photographic silver salt layers of photographic elements. In one of its aspects, the invention relates to the use of mercaptan stabilized monobaths containing a hydroquinone silver salt developing agent having at least one alkyl or aryl thio radical containing at least one water solubilizing group.

It is well known that developed silver salt layers of photographic elements containing silver images require the removal or inactivation of the residual unexposed silver salt for the image to be stable under adverse conditions of light, heat and humidity. For this reason, fixing and washing steps are ordinarily employed after development to convert the silver halide to a soluble salt which is then washed from the emulsion layer.

A number of processes have been proposed to simplify or avoid the two or more fixing and washing steps. In this connection, mercapto compounds have been found to be good silver complexing agents. For example, US. Pat. 2,453,346 of Russell issued Nov. 9, 1948, discloses the use of various sulfur compounds in conjunction with metal salts for stabilizing silver prints. Acidic solutions containing the sulfur compounds and metal salts are applied to silver halide emulsion layers following development of the silver image. In US. Pat. 2,525,532 of Dreywood, issued Oct. 10, 1950, emulsion layers are developed with a p-methylaminophenol-hydroquinone developer solution containing various sulfur compounds. Following development, the emulsions are treated with acid solutions prior to drying. In US. Pat. 2,614,927 of Broughton et al., issued Oct. 21, 1952, emulsions containing certain developing agents are processed with alkaline solutions followed by inactivation of the residual silver halide with solutions of sulfur compounds, such as thio glycolic acid, thiourea or thiosulfates.

Monobaths formed by the combination of developing agents with silver complexing agents have greatly simplitied the mechanics of processing photographic films, papers, etc., by developing and fixing the exposed element in a single solution. Monobaths are well known as described, for example, in The Monobath Manual by Grant M. Haist, 1966. US. Pat. 2,875,048 of Haist et al., issued Feb. 24, 1959, proposes a monobath composition comprising an alkaline solution of a hydroxylamine or 3-pyrazolidone developing agent and a monothioglycerol, thioglycol, fi-mercaptoethylamine, N,N-diethyl-fimercaptoethylamine or 2-thiobarbituric acid. While such mercaptan-containing monobaths are known, when mercaptan monobaths contain hydroquinone as a developing agent they rapidly lose the silver complexing activity of the mercaptan due to aerial oxidation.

In this connection, it mercaptan compound stabilizers are used with unsubstituted hydroquinones in certain monobaths, there is rapid reaction between the two and stable monobaths cannot be prepared. The monobaths and monobath processes of this invention overcome this problem while providing increased stability to oxidation with constant stabilizing activity without further addition of mercaptan stabilizers.

An object of the invention is, therefore, to provide means for producing stable silver images with mercaptancontaining monobaths which reduce loss in mercaptan complexing activity.

Another object of the invention is to provide a monobath process employing a mercaptan silver complexing agent which process is resistant to loss in mercaptan silver complexing activity.

These and other objects will be apparent from the following description.

It was surprisingly found that by employing a mercaptan monobath composition and process wherein a mono bath containing (a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one SRY radical wherein R is alkylene or arylene and Y is a water solubilizing group, and

(c) a development activator,

for developing and fixing an image in an exposed photographic silver salt emulsion (a) there is no undesired reaction of the mercaptan stabilizing agent with the hydroquinone silver salt developing agent,

(b) the desired monobath has increased stability to oxidation and (c) has longer constant stabilizing activity Without further addition of mercaptan stabilizing agent.

arylene and Y is a water solubilizing group, and (c) a development activator.

Monobaths are well known in the art, as set out in the references described. Monobath, as employed herein, means a composition containing a silver salt developing agent and a silver salt fixing or stabilizing agent. It usually refers to an aqueous solution of such developing agents and fixing or stabilizing agents. Monobaths within the scope of the invention effect both development and stabilization of the silver salt emulsion. Further definition of the term monobath is set out in. the book The Monobath Manual by Grant M. Haist, 1966.

A wide range of mercaptans can be employed in the monobaths of this invention as stabilizers for silver salts. Such mercaptan silver salt stabilizing agents can be any silver salt stabilizing agent mercaptan compound which is compatible with the components of the monobath and effects the desired fixing and/or stabilization. Suitable silver salt stabilizing agents include, for instance, those represented by the formula:

wherein R is an alkylene or arylene radical and Y is a water solubilizing group. Suitable alkylene or arylene groups include those which are substituted, such as those which contain mercaptan, i.e. SH, hydroxyl, and car- 3 boxyl groups, as Well as any groups which do not adversely aifect the stabilizing or fixing action of the mercaptan. R is typically an alkylene or arylene radical containing 1 to 20 carbon atoms, e.g., methylene, ethylene, propylene, butylene, isobutylene, isopropylene, hydroxypropylene (-CH CHOHCH carboxyethylene (CHCOOHCH phenylene, naphthylene, and xylylene ('CH2C6H4CH2) A water solubilizing group as employed herein is one which (a) has the effect of making the compound containing the group more soluble in water than the corresponding compound Without the Water solubilizing group and (b) has no substantial adverse affect on the stabilizing action of the mercaptan stabilizing agents or developing action of the developing agents employed in the practice of the invention. Such water solubilizing groups include, for example, hydroxyl and carboxyl radicals.

Useful mercaptan silver salt stabilizing agents include for instance:

mercaptoethanol HSCH CH OH mercaptopropanol HSCH CH CH OH mercaptoacetic acid HSCH COOH fl-mercaptopropionic acid HSCH CH -COOH mercaptobenzoic acid HSC H COOH mereaptosuceinic acid 0 O OH di-mercaptoadipie acid 0 O O H C O O H a-mereaptopropionic acid i H S --CH0 0 OH Any suitable concentration of mercaptan silver salt stabilizing agent can be employed in the monobath composition of the invention. An amount of about 1% to about 50% by weight of the total monobath composition is usually suflicient. For example, Where the monobath is an aqueous solution usually about 10 grams to about 500 grams of mercaptan silver salt stabilizing agent is sufiicient per liter of the total monobath. Concentrations outside this range can be employed.

The described hydroquinone silver salt developing agent can be any silver salt developing agent, typically a silver halide developing agent, which (a) afiects development of the exposed silver salt without adversely aifecting the other desired properties of the monobath, e.g., the desired stabilization action, (b) has a 1,4-dihydroxybenzene nucleus, and (c) has at least one SR-Y radical wherein R and Y are as described herein with respect to the aforementioned mercaptans employed in the monobaths of the invention as stabilizers. Mixtures of such developing agents can also be used. The 1,4-dihydroxybenzene nucleus can contain substituents in addition to the one or more S-RY radicals. These substituents can be any radical which does not adversely aifect the desired action of the monobath. For example, suitable substituents include hydroxyl, lower alkyl, e.g., methyl, ethyl, propyl, butyl, t-butyl and isopropyl, chloro or bromo radicals.

Any suitable amount of the described developing agent can be employed in the practice of the invention. An amount of developing agent of about 0.5% to about 10% wherein R is an alkylene or arylene radical containing 1- to 20 carbon atoms and Y is a water solubilizing group.

Hydroquinone silver salt developing agents which can be employed in the practice of the invention include:

-somc1non l on 2- 2,5-dihydroxyphenylthio ethanol 311 @somonomon a-hydroxy-,8- (2, S-dihydroxyphenylthio propanol on -sonzcoon I OH 2,S-dihydroxyphenylthioacetic acid on -s 011201120 0 01-1 I OH a 2,5 -dihydroxyphenylthio propionic acid (III) a-(2,5-dihydroxyphenylthio)propionic acid (VI) OH I SCHCH2OOOH 2,5-dihydroxyphenylthiosuccinic acid COOH o-(2,5-dihydroxyphenylthio)benzoic acid (VIII) OH I C O OH O O OH (VII) a- 2,5 -dihydroxyphenylthio -a'-mercaptoadipic acid (IX) OH OH I ('30 OH O OH I S CH H CS CHzC'Hz i I OH OH a,u'-Bis(2,5-dihydroxypheny thio)adipic acid Any development activator and any suitable concentration of development activator can be employed in the monobath of the invention which provides the desired alkalinity or pH to elfect the desired development. Typical development activators include inorganic development activators such as sodium hydroxide, potassium hydroxide and lithium hydroxide, as well as organic activators, such as organic amines, e.g. ethanolamine, morpholine, propanolamine, and the like. The pH of the monobath can vary over wide ranges, but in general a pH of at least 9 is employed, e.g., preferably about 10.0 to about 13.

Additional inorganic salts can be present in the desired monobath. These include, for example:

Al (N0 3 9H O Bi (Cal-I90 Ce 3) 3 CsCl PdCl

RbCl

((321 1302) 3 H2O PdCl RbCl RhCl SH O SbCl Sc ah Srn(NO SnCl TiCl V50 7H O Y3 YbCl 6H O YnCl These inorganic compounds have also been found effective in aiding stabilization and extending the active life time of other monobaths containing mercaptan stabilizing agents. Such monobaths are disclosed, for example, in an article by L. Corben, C. Bloom, D. Willoughby and A. Shepp in Journal of Photographic Science, vol. 14, No. 6, 1966, pages 297-303.

A typical monobath composition for developing and fixing a stable silver image in an exposed photosensitive element containing a silver salt emulsion according to the invention comprises an aqueous solution of (a) a stabilizing amount of a mercapto carboxylic acid or mercapto alkanol silver salt stabilizing agent, (b) a silver salt developing agent of the general formula:

wherein R is an alkylene or arylene radical containing '1 to 20 carbon atoms and Y is hydroxyl or carboxyl, and (c) an organic activator.

Monobath compositions within the scope of the invention can be prepared in any suitable manner. For example, the individual components of the monobath can be prepared prior to preparation of the monobath composition and mixed in an aqueous solvent before use or can be prepared in the monobath in situ. One especially suitable method comprises:

(1) adding a mercapton silver salt stabilizing agent to an aqueous solvent, e.g. dissolving a mercapto carboxylic acid silver salt stabilizing agent in water,

(2) adding a p-benzoquinone, i.e. a p-benzoquinone corresponding to the hydroquinone moiety of the described hydroquinone silver salt developing agent in an amount which is less than the stoichiometric quantity required to react with the mercaptan silver salt stabilizing agent,

(3) adding a development activator, typically an inorganic alkali, such as sodium hydroxide, potassium hydroxide or lithium hydroxide, to the aqueous solvent in suflicient quantity that the resulting solution is alkaline, and

(4) adding a mercaptan silver salt stabilizing agent, e.g. the mercapto carboxylic acid silver salt stabilizing agent of step 1.

The process need not be carried out in the respective order of steps 1 to 4. For example, the p-benzoquinone can be dissolved in or otherwise added to the aqueous solvent and then the mercaptan silver salt stabilizing agent added to the resulting solution before adding the development activator, or the development activator can be added to the aqueous solvent before the other compo nents are added.

A typical aqueous monobath of the invention is prepared by first dissolving a mercapto carboxylic acid in water. The pH of the resulting solution is usually below 6.0. p-Benzoquinone is then added with stirring in the ratio of 1 mole of p-benzoquinone to about 1.2 to about 1.5 moles of mercapto carboxylic acid. Suflicient water is employed to dissolve both of these components. Inorganic alkali, e.g. sodium hydroxide, is added until the pH of the solution is at least about 9.0, e.g. preferably 10.0 to about 13.0. Additional stabilizing agent is then added, typically more mercapto carboxylic acid. Usually a buffer, such as Z-aminoethanol, and a preservative, such as sodium sulfite, are then added followed by dilution of the monobath to the desired volume with water.

The process of preparing a monobath composition of the invention can be carried out under any suitable reaction conditions of temperature, pressure and the like. Typically, a monobath is prepared under ambient conditions, especially at room temperature, pressure, etc.

The hydroquinone silver salt developing agent having at least one SRY radical as described can be prepared before addition to the monobath composition of the invention. These compounds can be prepared by mixing the corresponding p-benzoquinone with a compound of the formula HS--RY wherein R and Y are as described, typically in an aqueous solvent. Any suitable reaction conditions can be employed, but in general the reaction can be carried out under ambient conditions. The p-benzoquinone compound and HSRY compound are typically mixed in stoichiometric quantities but mixtures outside these quantities can be employed. The resulting compounds can be separated from the aqueous solvent before addition to the monobath composition of the invention or the compounds can be added to the monobath with the aqueous solvent.

Any suitable p-benzoquinone compound can be employed for the preparation of the described hydroquinone silver salt developing agents including p-benzoquinone and 2-methyl-p-benzoquinone.

Another embodiment of the invention is a monobath process comprising developing and fixing a silver image in an exposed photosensitive element containing a silver salt emulsion layer with a monobath composition comprising: l

(a) a mercapto silver salt stabilizing agent,

(c) a development activator.

The hydroquinone silver salt developing agent typical- 1y has the described general Formula A and/ or the mercapto silver salt stabilizing agent is a mercapto carboxylic acid and/ or a mercapto alkanol.

The monobath compositions and processes of the invention are suitable for developing and fixing a wide variety of photosensitive emulsions, especially silver halide gelatino photosensitive emulsions. The photosensitive emulsions which can be developed and fixed with the compositions and processes of the invention include those which are non-spectrally sensitized, such as x-ray type emulsions, or emulsions which are orthochromatic, panchromatic, infrared sensitive, and the like, containing spectral sensitizing dyes such as described in US. Pats. 2,526,632 and 2,503,776. Spectral sensitizers which can be used in a photosensitive emulsion processed according to the invention include cyanines, merocyanines, styryls, and the like.

The photographic elements employed in the practice of the invention can be sensitized by using any of the well known techniques used in emulsion making, e.g. by digesting with naturally active gelatin or various sulfur, selenium, noble metal and/or gold compounds. The photosensitive emulsions employed in the practice of the invention, as well as the monobath compositions of the invention, can contain various photographic addenda, especially those known to be beneficial in photographic compositions. The types of addenda and amounts to be employed can be determined by those skilled in the art. Suitable addenda include, for example, hardeners, e.g. those set out in British Pat. 974,317; buffers which maintain the desired pH level including various sulfonamides and boraxes; coating aids; plasticizers; speed increasing addenda, such as quaternary ammonium salts and alkylene oxide polymers, and various stabilizing agents, such as sodium sulfite.

Various colloids can be used alone or in combination as vehicles or binding agents where one is used in the photosensitive emulsions and elements employed in the practice of the invention. Among such materials are the natural and/or synthetic binding materials generally employed for this purpose including, for example, gelatin, colloidal albumin, water soluble vinyl polymers, mono and polysaccharides, cellulose derivatives, proteins, water soluble polyacrylamides, polyvinylpyrrolidone and the like. In addition to the hydrophilic colloids, the vehicle or binding agents can contain dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable synthetic polymers of this type include water insoluble polyrmers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The silver salts processed according to the invention include any of the photosensitive silver salts, such as any of the photosensitive silver halides. Suitable silver halides include, for example, silver bromide, silver iodide, silver chloride or mixed halides, such as silver chlorobromide, silver bromoiodide, and the like. Preferred silver halides are those in which the halide comprises at least 50 mole percent chloride. 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, as well as direct positive emulsions such as those described in US. Pat. 2,541,472 of Kendall and Hill, issued Feb. 13, 1951.

The photosensitive emulsions processed according to the invention can be coated on a wide variety of supports. Typical supports include those generally employed for photographic elements, including various films, such as cellulose acetate films, cellulose nitrate films, polyethylene terephthalate films, or other polyester films, polycarbonate films and related materials, papers, such as paper supports coated with resinous materials, e.g. coated with polyethylene, polypropylene and/or polyethylenebutene copolymers, glass, metal, and the like.

In some cases it may be desirable to include morpholine or an aminoalkanol in the monobath compositions of the invention. These include any suitable aminoalkanols which have one, two or more hydroxy radicals. Suitable aminoalkanols include compounds within the formula:

wherein R is a hydroxyalkyl radical such as one containing up to ten carbon atoms, for example, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxyisobutyl, dihydroxylpropyl, dihydroxbutyl, and the like, R and R are each selected from the group consisting of hydrogen atoms and alkyl radicals, such as those containing up to about ten carbon atoms, such as methyl, ethyl, propyl, butyl, isobutyl, and isopropyl radicals. Suitable aminoalkanols which can be described as hydroxyalkylamines include:

Z-aminoethanol 2-methylaminoethanol 2-ethylaminoethanol 2-n-propylaminoethano1 Z-dimethylaminoethanol Z-diethylaminoethanol diethanolamine (2,2'-iminodiethanol) 2-aminopropanol 3-aminopropanol 3-diethylamino-1propanol l-dimethylamino-2-propanol 3dimethylamino-l,2-propane diol 4-aminobutanol 4-diethanolaminobutanol S-aminopentanol 5diethanolamino-2-pentanol 2-isopropylaminoethanol 2-amino-a-methyl-l-propanol triethanolamine S-diethanolaminopentanol methylolamine trimethylolamine 2- (di-n-propyl) aminoethanol 3-methylaminopropanol 2-methylolaminoetl1anol Any suitable amount of the aminoalkanol can be employed, usually about 1% to about 30% by weight of the total monobath composition being used.

A silver salt developing agent, the same as or difierent from the described silver salt developing agent, can be present in the photosensitive element employed in the practice of the invention. Such developing agents include any silver halide developing agent which is compatible with the components of the element and does not adversely affect the developing and fixing action of the monobath composition of the invention.

Suitable developing agents which can be employed include, for example, polyhydroxy benzenes, such as hydroquinone developing agents, e.g. hydroquinone, alkyl substituted hydroquinone, such as t-butylhydroquinone, methylhydroquinone, dimethylhydroquinone; catechol and pyragollol; chloro substituted hydroquinones, such as chlorohydroquinone, or dichlorohydroquinone; alkoxy substituted hydroquinone, such as methoxy or ethoxy hydroquinone; aminophenol developing agents, such as N-methyl-p-aminophenol and 2,4-diaminophenols; ascorbic acid developing agents; pyrazolidone developing agents, including those described in British Pat. 958,678 and British Pat. 930,572; acyl derivatives of p-aminophenol. Such developing agents can be used alone or in combination. It is especially desirable that the developing agents employed in the developer compositions be soluble in water.

The concentration of developing agent in the photosensitive element employed in the practice of the invention can vary over a wide range depending on many factors, such as the desired image, the components of the monobath composition, and the like. It can be the major developer used in the developing and fixing process of the invention or it can be an auxiliary developing agent.

It can be advantageous in some cases to have an antifoggant present in the monobath composition and/or in the photosensitive element employed in the practice of the invention. Suitable antifoggants include organic antifoggants, such as benzotriazole, benzimidazole, Z-mercaptobenzirnidazole and mercaptotetrazole antifoggants. Inorganic antifoggants, including potassium bromide, potassium iodide and/or sodium bromide, can be employed in the photosensitive element and/or monobath composition of the invention. Any suitable amount of antifoggant can be employed, depending on the components of the monobath composition, the photosensitive element, and the like.

Developing and fixing according to the practice of the invention can be carried out under any suitable conditions, usually ambient conditions, e.g. about 20 C. to about 30 C. However, higher temperatures can be employed if desired.

The time for processing employing the monobath composition of the invention can vary from about a second to several minutes or more depending on the desired image, processing conditions and the like.

The components of the monobath compositions of the invention can be stored in one or more separate containers such as in separate packets or bottles as part of a kit before use. At the time of use the components can be mixed together and/or diluted to the desired concentration. For example, the developing agent can be in one container and the stabilizing agent in another. The two compositions can be mixed before use.

The invention is further illustrated in the following examples.

EXAMPLE 1 This example illustrates preparation of a monobath according to the invention.

One hundred grams of mercaptosuccinic acid are dissolved in 600 cc. of water. Thirty cubic centimeters of an aqueous sodium hydroxide solution containing 40% by weight NaOH is added. Thirty grams of p-benzoquinone is then added slowly to the solution with agitation, the pH of the solution being below about 6.0. The solution is clear and only slightly yellow. An additional 35 grams of mercaptosuccinic acid is then added and then an aqueous solution of 40% by weight NaOH and water are added to bring the volume to 1 liter and the pH to about 1010.5. This monobath can be employed for developing and fixing an exposed photographic silver halide emulsion.

EXAMPLE 2 This example illustrates developing and stabilizing a photosensitive element with a monobath composition of the invention.

An exposed photographic paper having a medium grain silver chloride emulsion layer containing 1-phenyl-3-pyrazolidone as an incorporated developing agent at the rate of 1 mole of developing agent per mole of silver in the emulsion is developed and fixed by immersing in a monobath prepared as in Example 1. However, 50.0 grams of anhydrous sodium sulfite and 25.0 cc. of Z-aminoethanol are added to the monobath before the final dilution with water.

A stable image is developed and stabilized in the silver chloride emulsion layer within 6 seconds at about 20 C. Similar results are obtained when the compounds 2-(2,5 dihydroxyphenylthio)ethanol, on Ihydroxy 18 (2,5 dihydroxyphenylthio)propanol, 2,5 dihydroxyphenylthioacetic acid, 13-(2,5-dihydroxyphenylthio) propionicacid, a-(2,5-dihydroxyphenylthio) propionic acid, 2,5-dihydroxyphenylthiosuccinic acid, o-(2,5 dihydroxyphenylthio) benzoic acid, a-(2,5 dihydroxyphenylthio)-u-mercaptoadipic acid, and e d-bis(2,5-dihydroxyphenylthio)adipic acid are employed in the monobaths of this example.

EXAMPLE 3 This example illustrates preparation of a monobath according to the invention.

Thirty-five grams of thiolactic acid is added to 280 cc. of water. Thirty grams of p-benzoquinone and 300.0 cc. of water are added with stirring to the resulting solution. Eighty-eight grams of mercaptosuccinic acid is then added with 200 cc. of aqueous sodium hydroxide solution containing 40% by weight NaOH. Finally, 50.0 grams of am hydrous sodium sulfite, 25.0 cc. of Z-aminoethanol, and sufficient water are added to make 1 liter of solution.

An exposed medium grain silver chloride photographic emulsion is developed and stabilized within 6 seconds at about 20 C. in this monobath. The monobath is resistant to aerial oxidation also.

EXAMPLE 4 This is a comparative example illustrating advantages of a monobath of the invention over a monobath containing hydroquinone as the developing agent.

A mercaptan monobath is prepared having the following composition:

Mercaptosuccinic acid: 70.0 grams.

Sodium hydroxide (aqueous solution containing 40% by weight NaOH): 90.0 cc.

Hydroquinone: 31.0 grams.

Sodium sulfite (anhydrous): 50.0 grams.

Z-aminoethanol: 25.0 cc.

Water to make 1 liter.

This monobath has a pH of 10.2.

An identical monobath is prepared except that 2,5-dihydroxyphenylthiosuccinic acid is employed in place of hydroquinone as the developing agent.

At 20 C. each of these monobaths, upon initial preparation, develop and stabilize an image within 6 seconds in an exposed medium grain silver chloride emulsion layer on photographic paper. However, after 24 hours of exposure to air, the stabilizing activity of the first monobath is markedly decreased, while the second, i.e. a monobath of the invention, shows no evidence of significantly de creasing stabilizing activity.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be 1 1 effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A monobath composition for developing and fixing an exposed photosensitive silver salt layer comprising:

(a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having an -S-R-Y group wherein R is an alkylene or arylene group and Y is a hydroxy or carboxy group, and

(c) a development activator.

2. A monobath composition as in claim 1 wherein said hydroquinone silver salt developing agent contains at least one -S-R-Y radical wherein R is a 1 to 20 carbon atom alkylene or arylene radical.

3. A monobath composition as in claim 1 wherein said hydroquinone silver salt developing agent has the general formula wherein R is an alkylene or arylene containing 1 to 20 carbon atoms and Y is hydroxy or carboxy.

4. A monobath composition as in claim 1 wherein said hydroquinone silver salt developing agent is:

2- (2,5 -dihydroxyphenylthio ethanol,

a-hydroxy-p- 2,5 -dihydroxyphenylthio) propanol, 2,5-dihydroxyphenylthioacetic acid, p-(2,5-dihydroxyphenylthio)propionic acid,

a( 2,5 -dihydroxyphenylthio) propionic acid, 2,5-dihydroxyphenylthiosuccinic acid, o-(2,5-dihydroxyphenylthio)benzoic acid, a-(2,5-dihydroxyphenylthio)-a'mercaptoadipic acid, or a,a-bis (2,5 -dihydroxyphenylthio) adipic acid.

5. A monobath composition as in claim 1 wherein said mercaptan silver salt stabilizing agent is mercaptoethanol, mercaptopropanol, mercaptoacetic acid, B-mercaptopropionic acid, mercaptobenzoic acid, mercaptosuccinic acid, dimercaptoadipic acid, or a-mercaptopropionic acid.

6. A photographic process comprising developing and fixing a silver image in an exposed photosensitive element containing an exposed photosensitive silver salt layer with a monobath composition comprising:

(a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one -S-R-Y radical wherein R is alkylene or arylene and Y is a hydroxy or carboxy group, and

(c) a development activator.

7. A photographic process as in claim 6 wherein said hydroquinone silver salt developing agent has the general formula wherein R is an alkylene or arylene radical containing 1 to 20 carbon atoms and Y is a hydroxy or carboxy group.

8. A photographic process as in claim 6 wherein said mercapto silver salt stabilizing agent is mercaptoethanol, mercaptopropanol, mercaptoacetic acid, fi-mercaptopropionic acid, mercaptobenzoic acid, mercaptosuccinic acid, dimercaptoadipic acid, or a-mercaptopropionic acid.

9. A photographic process as in claim 6 wherein said exposed photosensitive element is developed and fixed with a monobath composition comprising:

(a) mercaptosuccinic acid,

(b) ,8-(2,5-dihydroxyphenylthio)succinic acid, and

(c) a development activator.

10. A photographic process as in claim 6 wherein said exposed photosensitive element is developed and fixed with a monobath composition comprising:

(a) mercaptosuccinic acid and thiolactic acid,

(b) a-(2,S-dihydroxyphenylthio)propionic acid, and

(c) a development activator.

11. A photographic process as in claim 6 wherein said photosensitive element contains a silver halide developing agent.

12. A process for preparing a stable aqueous monobath composition for developing and fixing an exposed photosensitive silver salt emulsion comprising:

(a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one -S-R-Y radical wherein R is alkylene or arylene and Y is a carboxylic acid radical, and

(c) a development activator comprising:

(a) adding a mercapto carboxylic acid silver salt stabilizing agent to an aqueous solvent,

(b) adding a p-benzoquinone to said aqueous solvent in an amount which is less than the stoichiometric quantity required to react with the said mercapto carboxylic acid,

(c) adding an inorganic alkali development activator to said aqueous solvent in sufiicient quantity that the resulting solution is alkaline, and

(d) adding a mercaptan silver salt stabilizing agent to the resulting solution.

13. A process as in claim 12 wherein said mercaptan carboxylic acid is mercaptosuccinic acid and said mercaptan silver salt stabilizing agent is also mercaptosuccinic acid.

References Cited UNITED STATES PATENTS 2,875,048 2/1959 Haist et al 96-66 2,525,532 10/1950 Dreywood 96-66 2,453,346 11/1948 Russell 96-61 2,614,927 10/ 1952 Broughton et al. 96-66 3,017,270 1/ 1962 Tregillus et a1. 96-61 3,033,765 5/1962 King et a1. 96-61 3,173,789 5/1965 King et al. 96-61 3,043,690 7/1962 Green et al 96-76 OTHER REFERENCES Haist Monobath Manual, Morgan & Morgan 1966, pp. 22, 23, 24, 31, 40, 41, 49

WILLIAM D. MARTIN, Primary Examiner M. SOFOCLEOUS, Assistant Examiner U.S. Cl. X.R.