US3615521A

US3615521A - Photographic compositions and processes-a

Info

Publication number: US3615521A
Application number: US764358A
Authority: US
Inventors: Edwin N Oftedahl Jr
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1968-10-01
Filing date: 1968-10-01
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26
Also published as: DE1949331A1; CA959323A; BR6912788D0; GB1284282A; CH517953A

Abstract

Photographic developing agents, which are lactone derivatives, such as coumarin derivatives and especially 6-hydroxy coumarin and 6-amino coumarin derivatives, and which have the property of forming a lactone developing agent precursor under neutral, slightly alkaline and acid conditions provide less stain without loss of desired sensitometric properties in photographic developer compositions, elements and processes. They are suitable in combination with other photographic developing agents. Corresponding lactone developing agent precursors are also especially useful.

Description

United States Patent [72] Inventor Edwin N. Oftedahl, Jr.

Rochester, N.Y. [21] App]. No. 764,358 [22] Filed Oct. 1, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Eastman Kodak Company Rochester, N.Y.

[54] PHOTOGRAPHIC COMPOSITIONS AND PROCESSES-A 16 Claims, No Drawings [52] U.S. Cl 96/66, 96/95 [51] Int. Cl G03c 5/30 [50] Field of Search 96/29, 29 D, 76, 95, 63, 64,65, 66; 117/34 [56] References Cited UNITED STATES PATENTS 3,043,690 7/1962 Green et al. 96/29 3,061,434 10/1962 Green et al. 96/76 X 3,232,758 2/1966 Holstead et al. 96/66 X 3,262,781 7/1966 Ryan et al 96/76 2,603,659 7/1952 Raasch 96/66 X OTHER REFERENCES Treatment of black-and-white motion picture photomaterials, Khaikin et al., U.S.S.R. 150,009, 9-14-62, Chemical Abstract, Vol. 58, p. 4086c.

Primary Examiner-William D. Martin Assistant Examiner-Theodore G. Davis Attorneys-R. E. Knapp, B, D. Wiese and W. H. J. Kline ABSTRACT: Photographic developing agents, which are lactone derivatives, such as coumarin derivatives and especially 6-hydroxy coumarin and 6-amino coumarin derivatives, and which have the property of forming a lactone developing agent precursor under neutral, slightly alkaline and acid conditions provide less stain without loss of desired sensitometric properties in photographic developer compositions. elements and processes. They are suitable in combination with other photographic developing agents. Corresponding lactone developing agent precursors are also especially useful.

PHOTOGRAPI'IIC COMPOSITIONS AND PROCESSES-A BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to photographic elements, processing compositions, especially developer compositions, and developing processes. In one aspect this invention relates to photographic elements, processing compositions and processes utilizing a photographic silver salt developing agent which has the property of forming a developing agent precursor under certain conditions. Another aspect relates to photographic elements, processing compositions and processes utilizing such a developing agent precursor.

2. The Prior Art It is well known to employ silver halide developing agents in processing photographic silver salt emulsions. It is also well known to incorporate silver salt developing agents into a layer of a photographic element containing a layer of a photosensitive silver salt. Typically, such emulsions are developed after exposure by treating them with a development activator, e.g., in a alkaline solution. Frequently, the alkaline solution will also contain a developing agent. Following development by either system, the developed silver image can be fixed or stabilized, for example, by treating the developed silver salt layer in a conventional fixing bath, such as a sodium thiosulfate or thiocyanate bath. The developed or fixed photographic silver salt layer can then be washed and dried.

Although use of a developing agent in a layer of a photographic element is convenient, it is frequently disadvantageous because the concentration of developing agent in the coating can be greatly reduced on storage for one or more reasons such as diffusion, sublimation, and the like. Also, the developing agent can become oxidized, and thus rendered ineffective, after relatively short period of storage. One of the methods proposed to overcome this problem is to incorporate a so-called developing agent precursor or blocked developing agent in one of the layers of the photographic element. These developing agent precursors are compounds which upon contact with a suitable activating agent form a silver halide developing agent. However, the developing agent precursors of the prior art also are not entirely successful and frequently are unable to form the desired developing agent within a suitable time period and/or form undesirable by-products which adversely affect the developing process. Further many of the better developing agents of the prior art in terms of speed and density rapidly oxidize to produce unsightly and objectionable black oxidation products which cause undesired stain.

There has accordingly been a need for developing agents and/or so-called developing agent precursors or blocked developing agents which provide reduced stain while maintaining or providing improved photographic speed, density and other desired sensitometric properties.

There has also been a need for developing agents and/or developing agent precursors which are acid quenchable. Developing agents and/or developing agent precursors which are acid quenchable include such compounds which have the property of providing desired developing action in the presence of a development activator and, when the desired degree of development is reached, such developing action can be stopped by lowering the pH and thus quenching the developing action by converting the developing agent to a developing agent precursor form. Developing agents which are acid quenchable and which have a ring closure mechanism to form a developing agent precursor have not been previously known.

While the synthesis and chemistry of lactone compounds which have a ring opening and closure mechanism under respectively alkaline and acid conditions are known, no lactones have been reported in photographic elements, compositions and/or processes as developing agent precursors. For example, the synthesis and chemistry of coumarins is described for instance by S. M. Sethma and N. M. Shah, Chemical Reviews,36, l, (I945); R. C. Elderfield, Hererocyclic Compounds, Volume 2, pages 173-216 (1951); and by R. Adams, Organic Reactions, Volume VII, pages l-58 (1953). Coumarin is known to form cinnamic acid salts under alkaline conditions. These compounds have not been employed heretofore in photographic elements or in developer compositions as a so-called blocked developing agent or developing agent precursor. Coumarin, for example, is not a suitable developing agent. The use of a 7,8-dihydroxy coumarin as a developing agent per se is described in U.S.S.R. Pat. No. 150,009 issued Sept. 16, 1962, (Chemical Abstracts, Volume 58, P4086e). British Pat. No. 767,70l Kodak discloses a 3- pyrazolidone developing agent with certain developing agents including 3,4-dihydroxycoumarin which like 7,8-dihydroxy coumarin has an ene-diol structure. There is no recognition nor suggestion in the art that a coumarin having hydroxy or amino in the 6 and/or 8 position would form a developing agent, nor is any indication given that such a coumarin compound can be employed as an incorporated developing agent or developing agent precursor.

Coumarin compounds have also been employed in photographic emulsions as sensitizers such as disclosed in French Pat. No. 1,349,658. However, such compounds are not developing agents or developing agent precursors.

Accordingly, it is an object of the invention to provide improved photographic elements containing an incorporated developing agent or developing agent precursor providing reduced stain while maintaining desired sensitometric properties.

Another object is to provide improved processing compositions, especially developer'compositions, and emulsions for photographic elements, such compositions containing a developing agent or developing agent precursor providing reduced stain while maintaining desired sensitometric properties.

A further object is to provide an improved method of developing a latent image in a photographic silver salt layer employing a lactone derivative silverhalide developing agent or developing agent precursor.

SUMMARY OF THE INVENTION According to the invention reduced stain without loss of desired sensitometric properties is provided in photographic elements, processing compositions, especially developer compositions, and processes by employing a lactone derivative silver halide developing agent which has the property of forming a lactone developing agent precursor under neutral, slightly alkaline and acid conditions, e.g., a pH about 9 or below and/or a lactone silver halide developing agent precursor which has the property of forming a lactone derivative silver halide developing agent in the presence of an alkaline development activator. Especially suitable photographic elements, processing compositions and processes according to the invention are those employing a. a described lactone derivative photographic silver halide developing agent such as a hydroxy cinnamic acid and/or an amino cinnamic acid, i.e., coumarin derivative, mixtures thereof, and their salts, e.g., their acid salts such as their chloride, hydrochloride, and sulfate salts, alkali metal salts, such as sodium or potassium and/or b. a hydroxy coumarin and/or amino coumarin developing agent precursor, especially a 6-hydroxy coumarin and/or 6- amino coumarin developing agent precursor, mixtures thereof and their salts, as described,

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wide range of lactone derivative silver halide developing agents which have the property of forming a lactone develop ing agent precursor under neutral and acid conditions can be employed according to the invention. These include any lactone derivatives which provide desired developing activity and reduction of stain without adversely affecting desired maximum density, minimum density, photographic speed and other desired sensitometric properties. Suitable lactone derivative developing agents include those which under neutral, slightly alkaline or acid conditions, i.e., when the pH is lowered to a level of about 9 or lower, i.e., about 2 to about 9, do not have significant developing activity, if any, due to formation ofa developing agent precursor.

The mechanism involved is believed to involve the opening and closing of an anhydro ring in lactone compounds depending on pH conditions. For instance, in the case of a 6-hydroxy coumarin and/or 6-amino coumarin developing agent precursor, under alkaline conditions such as a pH of about to about 14, the anhydro ring of such a lactone is believed to open forming a cinnamic acid developing agent, i.e., a coumarin derivative developing agent. This cinnamic acid developing agent has good developing properties.

A wide variety of hydroxy cinnamic acid and/or amino cinnamic acid developing agents can be employed according to to the invention. Suitable hydroxy cinnamic acid or amino cinnamic acid developing agents include any such compounds which cause reduction of a photographic silver salt in exposed areas of a layer containing such photographic silver salt without adversely affecting the unexposed areas of the photosensitive silver salt. Especially suitable developing agents are derivatives of 6-hydroxy coumarins, 6-amino coumarins, mixtures thereof, and their salts. Suitable cinnamic acid developing agents of the invention include compounds of the formula:

a. R and R are individually hydrogen, halogen, e.g., chlorine, bromine or iodine, or alkyl, e.g., alkyl containing one to five carbon atoms such as methyl, ethyl, propyl, butyl and pentyl,

b. R and R are individually hydrogen, alkyl, e.g., alkyl containing one to eight carbon atoms such as methyl, ethyl, propyl, butyl and pentyl, alkoxy, e.g., alkoxy containing one to five carbon atoms such as methoxy, ethoxy, propoxy, butoxy and pentoxy, halogen, as described, and aryl, e.g., aryl containing up to 20 carbon atoms, such as phenyl, tolyl and xylyl,

c. R, and R are individually hydrogen, hydroxy, amino, i.e., NH NHR or -NRR wherein R and R are alkyl containing one to five carbon atoms, such as methyl, ethyl, propyl, butyl and pentyl; alkyl containing one to five carbon atoms, as described, alkoxy containing one to five carbon atoms, as described, aryl, e.g., aryl containing up to 20 carbon atoms such as phenyl, tolyl and xylyl,

mixtures thereof, and their salts, e.g., acid salts such as chloride, hydrochloride and sulfate salts, or alkali metal salts, and wherein at least one of R and R is hydroxy or amino.

Esters such as alkyl esters containing one to five carbon atoms, typically a methyl ester, ethyl ester, propyl ester, or butyl ester of the described cinnamic acid compounds, e.g., those within structure l, are also developing agents. However, if an ester of a compound of structure I is formed this can hinder or prevent the formation of a developing agent precursor as described. Accordingly, in some cases it can be undesirable to include compounds in a photographic element, composition or process accordingly to the invention which cause formation of esters, typically alkyl esters of the described cinnamic acid developing agents.

Suitable cinnamic acid developing agents include:

[3,4-dimethyl-2,5-dihydroxy cinnamic acid;

4-methyl-2,5-dihydroxy cinnamic acid;

6-bromo-4-methyl-2,S-dihydroxy cinnamic acid; 2-hydroxy-5-amino cinnamic acid;

wherein R,, R R R R and R are described for structure I. Examples of developing agents within structure ll include:

- CH:C 0 OH IIO- CHz-COOH s 2)1- -OH and CI'Ir-C O OII Also included are compounds which are derivatives of 3,4- dihydrocoumarins. These include compounds of the formula:

(III) l 1: 1 R4- -C-C=COOII Rs OH wherein R R R R R and R are as described for Structure 1. Examples of compounds within Structure l Il include:

Also a wide range of lactone silver halide developing agent precursors can be employed which have the property of forming a lactone derivative silver halide developing agent in the presence of an alkaline development activator, e.g., under a1 kaline conditions including a pH of about 8 to 14, typically a 5 pH of about 10-14, preferably a pH of about 12 to about 14. Suitable lactone developing agent precursors include any lactones which in the presence of an alkaline development activator have the property of forming a lactone derivative silver halide developing agent, typically, it is believed, by opening of the anhydro ring of the lactone, and in the presence of such a development activator provide desired developing activity and reduction of stain without adversely affecting desired maximum density, minimum density, photographic speed and other desired sensitometric properties.

Suitable hydroxy coumarins and amino coumarins which are developing agent precursors according to the invention include developing agent precursors of the formula:

(IV) R:

wherein R,, R R R R and R,, are as described for strucwherein R R R R R and R,, are as described for structure I, with the exception that R can also be aryl, as described, especially phenyl, tolyl or xylyl. Examples of developing agent precursors within structure V include:

clude 3,4-dihydrocoumarin developing agent precursors corresponding to the coumarin developing agent precursors of structure 1V. Examples of 3,4-dihydrocoumarin developing agent precursors include:

6,7-dihydroxy-4-methyl-3,4-dihydrocoumarin and 7,8-dihydroxy-4-methyl-3,4-dihydrocoumarin.

The developing agents and/or developing agent precursors of the invention are suitable in a range of physical locations in a photographic system. They can be employed in one or more layers of a photographic element and/or in a processing composition if desired. For example, they can be employed in developer compositions, such as an aqueous alkaline developer solution, or can be incorporated into a layer, such as a silver halide emulsion layer, or overcoat layer of a photographic element. They can be employed, as described, for example, in copending U.S. Pat. application, Ser. No. 764,301 of Oftedahl, filed Oct. 1, 1968, titled Photographic Compositions and Processes (8)" in elements, e.g., photographic elements and/or image receivers and/or processing compositions, e.g., developer compositions intended for use in diffusion transfer processes. Diffusion transfer processes and photographic elements in which the developing agents and/or developing agent precursors are useful as described, for example, in U.S. Pat. Nos. 2,352,014 of Rott issued June 20, 1944', 2,543,181 of Land issued Feb. 27, 1951; and 3,337,342 of Green issued Aug. 22, 1967. They can be used also in socalled high-speed diffusion transfer processes as described, for example, in U.S. Pat. No. 3,326,683 of Land et al. issued June 20, 1967; or in other types ofdiffusion transfer processes such as those described in U.S. Pat, Nos. 2,857,274 of Land et al. issued Oct. 21, 1958; 3,020,155 of Yackel et al. issued Feb. 6, 1962; 2,584,030 of Land issued Jan. 29, 1952; and 2,923,623 ofLand issued Feb. 2, 1960.

An alkaline development activator can be employed to activate the developing agents and/or developing agent precursors of the invention which provides the desired pH. These include those commonly employed in the photographic art as development activators, such as inorganic alkalies, e.g., alkali metal hydroxides including sodium hydroxide, potassium hydroxide and lithium hydroxide, alkali metal carbonates, such as sodium carbonate, sodium bicarbonate and the like, as well as organic alkalies such as organic amines and aminoalkanols, e.g., ethanolamine and iminodiethanolamine or morpholine. The concentration of development activator suitable will vary depending on the various components of the system, the photographic emulsion employed, the desired image, and the like. A concentration is usually employed which provides a pH of at least about 10, typically about 10 to about 14 and preferably about 12 to about 14. Upon treatment with an alkaline activator, it is believed the lactone ring of the described coumarin compounds, for example, opens to yield a hydroxy group and thus a strong developer. The developing action can be stopped, or returned to its initial precursor form by returning the developing agent form, for example, to the developing agent precursor form by treatment with an acid, e.g., usually a mild acidic solution such as an aqueous acetic acid, carbonic acid, hydrochloric acid, boric acid or nitric acid solution. This property is referred to as acid quenching and is especially useful in photographic processes where residual oxidation or developer activity is undesirable. The foregoing relationship or reaction can be illustrated by the following equation employing coumarins as an example:

coumarin form cinnamic acid form Developer precursor Developing agent wherein R,, R R R R and R are as described for structure I.

In order to obtain the desired developing action upon conversion to the cinnamic form the coumarin preferably has a hydroxy group or an amino group or a derivative of these groups which is in the 6 position (i.e., R and/or 8 position (i.e., R This hydroxy or amino group is para or ortho in the cinnamic form, to the unblocked hydroxy group.

The lactone derivative developing agents and lactone developing agent precursors, e.g., coumarins or cinnamic acid compounds used in the practice of the invention, can be prepared by conventional methods known to the art or by obvious modifications of such methods to obtain derivative or substituted products. Various methods for preparing a given coumarin, as described, can, for example, be obtained from the following sources: 7-methyl-6-hydroxy coumarin-Desni and Mavani, Proc. Indian Acad. Sci., 25A, 327 (1947); 4,7- dimethy-6-hydroxy coumarin-Desni and Mavani, Proc. Indian Acad. Sci., 15A, ll (1942); and 6-amino coumarinG. Morgan, J. Chem. 806., Transactions 85, l233 1904). Further preparations can be obtained from the prior art and also from the described references.

The described hydroxy cinnamic acids and/or amino cinnamic acids and their salts can be prepared by known processes or, as in the practice of the invention, by the alkalation of the respective coumarin.

The described developing agents and developing agent precursors according to the invention can be employed in one or more layers of a photographic element. Accordingly, one embodiment of the invention comprises in an element comprising a support containing at least one layer comprising a photographic silver halide developing component the improvement comprising a lactone derivative photographic silver halide developing agent which has the property of forming a lactone developing agent precursor under neutral and acid conditions. The lactone derivative developing agent is typically selected from coumarin derivatives, mixtures thereof and their salts, especially, derivatives of 6-hydroxy coumarins, 6-amino coumarins mixtures thereof, and their salts. These compounds can be employed in a photographic silver salt emulsion layer, an overcoat layer, a layer under the emulsion layer, a baryta layer, an antihalation layer, or virtually any layer contiguous to the silver salt to be developed. For instance, the developing agents and developing agent precursors of the invention can be employed in a photographic element having a layer containing:

a. a silver halide developing agent which is a hydroxy cinnamic acid and/or an amino cinnamic acid, and/or b. a sliver halide developing agent precursor which is a hydroxy coumarin and/or an amino coumarin, and a photographic silver salt layer.

Another embodiment of the invention comprises in an element comprising a support having at least one layer comprising a photographic silver halide developing component the improvement comprising a lactone silver halide developing agent precursor which has the property of forming a lactone derivative silver halide developing agent in the presence of an alkaline development activator. Such an element typically contains a developing agent precursor, as described, selected from the group consisting of 6-hydroxy coumarin and 6-amino coumarin developing agent precursors, mixtures thereof, and their salts.

The developing agents and/or developing agent precursors described can be employed for developing an image in a wide range of photographic emulsions in photographic systems.

The photographic emulsions employed can be X-ray or other nonspectrally sensitized emulsions or they can contain spectral-sensitizing dyes such as described in US Pat. Nos. 2,526,632 and 2,503,776. Spectral sensitizers which can be used include cyanines, merocyanines, styryls and hemicyanines.

Various photographic silver salts can be used in the practice of the invention. These include photographic silver halides such as silver iodide, silver bromide, silver chloride, as well as mixed halides such as silver bromoiodide, silver chloroiodide and the like. Photographic silver salts which are not silver halides can also be employed such as silver salts of certain organic acids.

Photographic coatings which are suitable can be coated on a wide variety of supports. Suitable supports include those generally employed for photographic elements, such as, for example, cellulose acetate films, cellulose nitrate films, polyethylene terephthanlate films, or other polyester films, polycarbonate films and related films or resinous materials; as well as papers, such as paper supports coated with resinous materials, e.g., coated with polyethylene, polypropylene and/or ethylene-butene copolymers; glass; metal, and the like. The supports or layers coated on them can contain fluorescent-brightening agents such as stilbenes, benzothiazoles and benzoxazoles. Some of the coumarin compounds described can also act as brightening agents.

The photographic elements processed according to the invention typically contain an emulsion layer comprising any of the known binding materials suitable for photographic purposes. These include natural and synthetic binding materials generally employed for this purpose, for example, gelatin, colloidal albumin, water soluble vinyl polymers, such as mono and polysaccharides, cellulose derivatives, proteins, water soluble polyacryl amides, polyvinyl pyrrolidone and the like, as well as mixtures of such binding agents. These binding materials can include water insoluble polymers such as polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like. The elements can also contain stripping layers and/or antistatic layers (i.e., conducting layers).

The developing agents and/or developing agent precursors of the invention can be employed in combination with addenda known in the art to be useful in and/or for processing photographic elements. For instance, the photographic emulsions and compositions of the invention can contain various photographic addenda, particularly those known to be beneficial in photographic compositions. The various addenda and concentrations to be employed can be determined by those skilled in the art. Suitable photographic addenda include hardeners, e.g., those set forth in British Pat. No. 974,317; buffers which maintain the desired developing activity and/or pl-l level, coating aids, plasticizers, speed increasing addenda, such as amines, quaternary ammonium salts, sulfonium salts, and alkylene oxide polymers; and various stabilizing agents, such as sodium sulfite. The photographic silver salt emulsions of the invention can also be chemically sensitized with compounds of the sulfur group such as sulfur, selenium and tellurium sensitizers, noble metal salts such as gold, or reduction sensitized with reducing agents or combinations of such materials.

Developing agents and developing agent precursors as described can also be used in layers of photographic elements or processing solutions intended for use in monobath processing such as described in U.S. Pat. No. 2,875,048 of Haist et al. issued Feb. 24, 1959, and British Pat. No. 1,063,844 of Beavers et al. issued Mar. 30, 1967, and in webtype processing, such as described in U.S. Pat. No. 3,l79,5 l7 ofTregillus et al. issued Apr. 20, 1965.

The developing agents and developing agent precursors of the invention can be employed in photographic elements designed for processing in stabilization type processing. For example, they can be incorporated in one or more layers of a photographic element which is exposed, activated by contact with alkaline activator, and then contacted with a thiocyanate or thiosulfate solution, such as ammonium thiocyanate, or they can be incorporated in the alkaline activator. Such processes are described, for example, in U.S. Pat. No. 3,326,864 of Nishio issued June 20, I967; British Pat. No. 1,004,302; French Pat. No. 1,516,556 of Fassbender; and in an article by H. D. Russell E. C. Yackel and E. G. Grouse in the PSA JOURNAL, Aug., 1950, pages 59-62, entitled Stabilization Processing of Films and Papers."

The developing agents and developing agent precursors employed according to the invention can also be present in one or more layers of a photographic element designed for recording color images and/or in processing compositions employed with such elements. For example, these compounds can be employed in one or more layers of a photographic element containing a photographic layer sensitive to the blue region of the spectrum, a photographic layer sensitive to the green region of the spectrum, and a photographic layer sensitive to the red region of the spectrum. The layers sensitive to the blue, green and red regions of the spectrum can contain any suitable sensitizing dyes. Photographic elements designed for recording color images in which and/or for which the developing agents and developing agent precursors of the invention are useful are described, for example, in Mees, The Theory of the Photographic Process, 3rd Edition, pages 382-396.

A photographic element and/or processing composition according to the invention can also contain toning agents such as, for example, polyvalent inorganic salts of the type described in U.S. Pat. No. 2,698,236 of Land issued Dec. 28, 1954; silica as described in U.S. Pat. No. 2,698,237 of Land issued Dec. 28, 1954; and heterocyclic mercaptans such as the mercapto azoles, e.g., mercapto diazoles, mercapto triazoles and mercapto tetrazoles.

The developing agents and/or developing agent precursors of the invention can be employed in combination with any silver halide developing agent. The developing agents and/or developing agent precursors of the invention can be employed in such combinations as auxiliary developing agents or as the main components of the developer combination and/or developing agent precursor combination. Suitable silver halide developing agents which can be employed with the developing agent or developing agent precursor of the invention include, for example, polyhydroxybenzenes, such as hydroquinone developing agents, e.g., hydroquinone, alkyl substituted hydroquinones, such as t-butyl hydroquinone, methyl hydroquinone and 2,5-dimethylhydroquinone; catechol and pyrogallol; chloro substituted hydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxy substituted hydroquinones such as methoxy hydroquinone or ethoxy hydroquinone; aminophenol developing agents, such. as 2,4-diaminophenols, e.g., 2,4-diamino-6-methyl phenol, and methylaminophenols; ascorbic acid, ascorbic acid ketols, such as those described in Green U.S. Pat. No. 3,337,342 issued Aug. 22, 1967; hydroxylamines such as N,N-di(2-ethoxyethyl)amine, 3-pyrazolidone developing agents such as lphenyl-3-pyrazolidone, including those described in British Pat. No. 930,572; and acyl derivatives of p-aminophenol such as described in British Pat. No. 1,045,303. Such developing agents can be used alone or in a combination when used with the developing agents or developing agent precursors of the invention.

The developing agents and/or developing agent precursors of the invention can be used in combination, for example, with one or more of the following compounds:

l-phenyl-3-pyrazolidone hydroquinone methyl hydroquinone 2,5-dimethyl hydroquinone 2,6-dimethyl hydroquinone tertiary butyl hydroquinone 3,6-dihydroxy benzonorbornane 2,4-diamino-6-methyl phenol dihydrochloride 4-phenyl catechol tertiary butyl pyrocatechol 2,4-diaminophenol dihydrochloride ascorbic acid N-methyl-p-aminophenol sulfate N,N-ethylene di(oxymethyl)pyridinum perchlorate 2-( 3-sulfopropyl)-2-thiopseudo urea 7,-14-diaza-6,lS-dipxoeicosane-l,ZI-bis-(pryidinium perchlorate) These compounds, for instance can be incorporated in a photographic element employed in a diffusion-transfer system, which after exposure can be developed employing a developer composition containing a developing agent and/or developing agent precursor of the invention.

One or more of the described combination of compounds can be in a photographic element and/or processing composition, e.g., developer composition of the invention. For example, a photographic element can contain a 3-pyrazolidone developing agent, such as l-phenyl-3-pyrazolidone and/or lphenyl-4,4-dimethyl-3-pyrazolidone, and/or a 2,4- diaminophenol developing agent, such as 2,4-diamino-6- methylphenol and/or 2,4-diamino-6-methoxyphenol, and be developed employing a developer composition containing a developing agent and/or developing agent precursor of the invention, e.g., a 6-amino coumarin and/or 6-hydroxy coumarin, as described, such as 4,7-dimethyl-6-hydroxycoumarin.

The developing agents and developing agent precursors of the invention can be employed in processing compositions in any form suitable for developing an exposed photographic element. For example, they can be employed as mixtures such as mixtures of the developing agents and/or developing agent precursors of the invention as auxiliary developers with other developing agents. They can be supplied as an aqueous silver halide developer solution or liquid concentrate; as a component of a solid particulate composition suitable for dissolving in a solvent such as an aqueous solvent; as a viscous composition containing various thickening agents; as a packaged component of a kit for mixing with various processing agents or as a component of a fusible solid such as a solid containing a homogeneous of an alkaline oxide polymer and a developing agent precursor of the invention which melts above about room temperature, and the like.

Another embodiment of the invention is in a photographic processing composition comprising a silver halide developing component and an alkaline development activator the improvement comprising a lactone derivative silver halide developing agent which has the property of forming a lactone developing agent precursor under neutral, slightly alkaline and acid conditions.

A photographic processing composition includes any compositions commonly employed for processing photographic elements, such as developer compositions, e.g., developer solutions or solid particulate compositions suitable for dissolving in a suitable solvent such as water, ethanol, ethylene glycol and the like, stabilizer compositions, monobaths, activator compositions, hardener compositions and the like.

A typical composition according to this embodiment is a developer composition comprising a silver halide developing component, which is a hydroxy cinnamic acid and/or amino cinnamic acid'developing agent, e.g., within structure I, mixtures thereof and their salts; and/or a 6-hydroxy and/or 6- amino coumarin developing agent precursor, as described, e.g., within structure IV, mixtures thereof and their salts.

A composition according to the invention can contain a silver halide solvent. A wide range of silver halide solvents are suitable, such as alkali metal and ammonium thiocyanates, e.g., sodium and potassium thiocyanate and ammonium thiocyanate, alkali metal thiosulfates, such as sodium thiosulfate and potassium thiosulfate, thiourea compounds, and the like.

A further embodiment of the invention is in a photographic processing composition, typically a developer precursor composition, comprising a silver halide developing agent precursor the improvement comprising a lactone silver halide developing agent precursor, as described, which has the property of forming a silver halide developing agent in the presence of an alkaline de\ elopment activator.

A further embodiment of the invention is in a photographic process for developing a latent image in a photographic silver salt layer of a photographic element wherein the silver salt layer is contacted with a developing component in the presence of an alkaline development activator the improvement wherein the developing component comprises a lactone silver halide developing agent precursor which has the property of forming a lactone derivative silver halide developing agent in the presence of the alkaline development activator.

According to this embodiment, the invention can comprise a process of developing a latent image in a photographic silver salt layer by contacting the silver salt layer with a processing composition containing a silver halide solvent and a silver halide developing agent precursor, as described, such as a hydroxy coumarin and/or an amino coumarin developing agent precursor.

The process according to this embodiment can also employ another silver halide developing agent, as described, either as the main developing agent or as an auxiliary developing agent in a layer of a photographic element processed and/or in the silver halide developing precursor composition. Developing action, which is effected upon contact of the developing agent precursor with a suitable activator, can be stopped by merely lowering the pH in the vicinity of the developing agent and thus returning the developing agent to its precursor form. Suitable activators which can be used include those described, and especially those which yield a pH of about 10.0 or greater.

Another embodiment of the invention is in a photographic process comprising developing a latent image in a photographic silver salt layer of a photographic element employing a silver halide developing agent in the presence of an alkaline development activator the improvement comprising developing said latent image with a lactone derivative silver halide developing agent, as described, which has the property of forming a lactone developing agent precursor under neutral and acid conditions.

According to this embodiment a process is provided for developing a latent image in a photographic silver salt layer of a photographic element by contacting the silver salt layer with a developing agent which is, for example, a cinnamic acid developing agent, as described, i.e., a derivative ofa coumarin developing agent precursor, as described, in the presence of an alkaline development activator.

Further development or oxidation can then be stopped, thus preventing or substantially reducing developer stain, by lowering the pH of the developer to a neutral, slightly alkaline or acid condition, i.e., below about 9. As described, the lowering of the pH causes the hydroxy cinnamic acid and/or amino cinnamic acid, for example, to form its respective coumarin form which has only weak, and usually negligible developing activity, if any.

The activating pH according to this process should range from about to 14 and best results are obtained when the pH is above about 12. The quenching pH range should be about from about 9 to 2. The optimum pH for any system will in many cases also be influenced by the photographic element, the desired image, the various addenda used in the developer, emulsion or layers, etc.

The concentrations .of the developing agents and/or developing agent precursors used in the practice of the invention can vary over wide ranges depending upon the particular photographic and physical variable present in the system, for example, the position of the developing agent and/or developing agent precursors in the photographic element, the developer composition, the desired image, etc. Suitable concentrations are also dependent on processing conditions, ad-

' denda present in the photographic element to be processed and/or in the processing compositions. Suitable optimum concentrations can easily be determined by those skilled in the art through routine experimentation. Typically, when a developing agent according to the invention is employed in a photographic element, it is employed in the concentration of about 0.01 to about 5 moles of developing agent per mole of silver present in the photographic element. When a developing agent precursor is employed in a photographic element, it is typically employed in a concentration which provides about 0.01 to about 5 moles of developing agent per mole of silver present in the photographic element upon activation. Usually about 0.01 to about 5 moles of developing agent precursor per mole of silver present is sufficient. When a developing agent and/or developing agent precursor composition, as described, is employed to process a photographic element, the total concentration of developing agents and precursors is typically about 0.0l to about l0, e.g. l to 5, percent by weight of the total developer composition. The particular developing time required can vary over a wide range between a few seconds up to an hour or more, depending on the desired image, and the various addenda etc. present; optimum developing time can also, however, be obtained by routine experimentation.

It is often advantageous to have an antifoggant present in the developer compositions of the invention and/or in the photographic element processed according to the invention. Suitable antifoggants include organic antifoggants, such as benzotriazole, benzimidazole, Z-mercaptobenzimidazole, nitroindazole, and mer'captotetrazole antifoggants. The developer compositions of the invention can contain an inorganic antifoggant, such as potassium bromide, potassium iodide and/or sodium bromide. The concentration of antifoggant in either the developer composition or element can be varied depending upon the desired image, other components present, subsequent processing steps and the like. The developer typically contains less than about 2 percent by weight of the antifoggant and usually in the range of about 0.01 to 2 percent by weight. Copending U.S. Pat. application, Ser. No. 764,30! of Oftedahl, filed Oct. 1, 1968, titled Photographic Compositions and Processes (B)" sets out use of developing agents and/or developing agent precursors, described herein, especially 6-hydroxy coumarins and/or 6- amino coumarins, with photographic diffusion transfer systems. The disclosure in this application is incorporated herein by reference. It will be appreciated that the requirements for developing agents and/or developing agent precursors in diffusion transfer systems set out in that application are very stringent compared to photographic systems in general.

A further understanding of the invention can be had from the following examples.

EXAMPLE 1 This example illustrates a photographic element comprising an incorporated developing composition according to the invention.

In this example an initial coating is prepared by admixing an aqueous solution containing 2 ml. of IO percent (wt.) saponin; 4ml. of aqueous sodium bisulfate solution (I mg./ml.); 17 ml. of methanol containing one-quarter ml. of dimethylacetamide; 640 mg. of 7-methyl-6-hydroxy coumarin, and 0.8 ml. of 10 percent (wt.) formaldehyde to 26 g. of 10 percent (wt.) gelatin. The admixture is then coated on a cellulose acetate film support at a coverage of 500 mg. gelatin/ft. and dried. A silver halide emulsion mixture is prepared by admixing 13 ml. of a silver chlorobromide emulsion, 2 ml. of 10 percent (wt.) saponin, l5 g. of 10 percent (wt.) gelatin, 1.2 ml. of aqueous sodium bisulfite solution (1 mg./ml.), 200 mg. of 7-methyl-6- hydroxy coumarin dissolved in 18.5 ml. of methanol containing one-quarter ml. of dimethylacetamide, and 0.6 ml. of i percent (wt.) formaldehyde. The emulsion mixture is then coated over the dried initial coating at a silver coverage of about 190 mg. Ag./ft. and dried.

The coating is exposed through a step wedge and processed by bathing for 2 minutes on an alkaline activator, consisting of an aqueous sodium hydroxide solution having a pH of 12 to 14, stopped, fixed and washed. 17 steps are visible on the layer after it is processed.

EXAMPLE 2 This example illustrates a developer composition and developing process according to the invention.

. In this example a developer solution, designated as developer solution (A), is prepared by dissolving g. of 6- amino coumarin, 50 g. of sodium hydroxide, and l g. of Na,. SO in sufficient distilled water to provide 1 liter of solution.

A 12 inchX35 mm. strip of a paper support coated with a silver chlorobromide gelatin emulsion is exposed sensitometrically for 1 second. The exposed strip is then processed for 2 minutes in the described developer solution (A).

steps are visible on the emulsion layer. The resulting minimum density is 0.04, maximum density is 0.26, and gamma is 0.20. The element is free of stain.

EXAMPLE 3 This is a comparative example.

The process of example 2 is repeated with the exception that the developer solution contains 5 g. of 6,7-dihydroxy-4- methyl coumarin in place of 6-amino coumarin.

An exposed emulsion as set out in example 2 is developed by contacting it with the developer solution.

13 steps are visible in the developed image. The resulting minimum density is 0.03, maximum density is 0.30 and gamma is 0.20.

This example illustrates that the 6-amino coumarin of example 2 though possessing a structure which would appear not to provide developing activity, is virtually as effective as a developing agent as 6,7-dihydroxy-4-methyl coumarin.

EXAMPLE 4 Similar results are obtained as in example 1 employing one of the following compounds:

8-Hydroxycoumarin EXAMPLE 5 5-Hydroxy-2-coumaranone EXAMPLE 6 5-Hydroxy-3-phenyl-2-coumaranone EXAMPLE 7 5-Hydroxy-6-octyl-2-coumaranone EXAMPLE 8 7-Hydroxy-2-coumaranone EXAMPLE 9 6-Hydroxy-2-ketol ,4-benzoxathian EXAMPLE l0 7,8-Dihydroxy-3-methyl-3,4-dihydrocoumarin EXAMPLE ll 7,8-Dihydroxy-4-methylcoumarin in place of 7-methyl-6-hydroxy coumarin.

R: Bi

I Ra

wherein:

a. R and R are individually selected from the group consisting of hydrogen, halogen and alkyl containing one to five carbon atoms;

. R and R are individually selected from the group consisting of hydrogen, alkyl containing one to five carbon atoms, alkoxy containing one to five carbon atoms, halogen and aryl containing up to 20 carbon atoms; and

. R and R, are individually selected from the group consisting of hydroxy, amino, hydrogen, alkyl containing one to five carbon atoms, alkoxy containing one to five carbon atoms and aryl containing up to 20 carbon atoms; mixtures thereof and their salts; and wherein at least one of R and R is hydroxy or amino.

2. An element as in claim 1 also comprising a photographic silver salt layer.

3. An element as in claim 1 also comprising a second silver halide developing agent.

4. An element as in claim 1 wherein said silver halide developing component is [3,4-dimethyl-2,S-dihydroxy cinnamic acid.

5. A photographic element comprising a support, photographic silver halide and 2,5-dehydroxy cinnamic acid or 2- hydroxy-S-amino cinnamic acid silver halide developing agent.

6. A photographic-processing composition comprising an alkaline development activator and a 2,5-dihydroxy cinnamic acid or a 2-hydroxy-5-amino cinnamic acid silver h .lide developing agent.

7. A photographic-processing composition as in claim 6 also comprising a silver halide solvent.

8. A photographic-processing composition as in claim 6 also comprising a second silver halide developing agent.

9. A photographic-processing composition as in claim 6 wherein said silver halide developing agent is an auxiliary developing agent.

10. A photographic-processing composition as in claim 6 wherein the pH of the developer composition is about 10 to about 14.

11. A photographic processing composition as in claim 6 wherein said silver halide developing agent is present in a concentration of 0.0] to 10 percent by weight of said processing composition.

12. A photographic processing composition comprising an alkaline development activator and a coumarin developing agent precursor of the formula:

wherein:

a. R and R, are individually selected from the group consisting of hydrogen, halogen, and alkyl containing one to five carbon atoms;

b. R and R are individually selected from the group'consisting of hydrogen, alkyl containing one to five carbon atoms, alkoxy containing one to five carbon atoms, halogen and aryl containing up to 20 carbon atoms; and

c. R, and R are individually selected from the group consisting of hydroxy, amino, hydrogen, alkyl containing one to five carbon atoms and aryl containing up to 20 carbon atoms; salts of such coumarin compounds; mixtures thereof; and wherein at least R is hydroxy or amino.

14. A photographicprocessing composition comprising an alkaline development activator and B,4-dimethyl-2,5- dihydroxy cinnamic acid. A

15. A photographic emulsion comprising a photographic silver salt and a lactone derivative silver halide developing agent which is selected from the group consisting of cinnamic acid developing agents of the formula:

wherein:

a. R and R are individually selected from the group consisting of hydrogen, halogen, and alkyl containing from one to five carbon atoms;

b. R and R are individually selected from the group consistlng of hydrogen, alkyl containing one to five carbon atoms, alkoxy containing one to five carbon atoms, halogen and aryl containing up to 20 carbon atoms; and

c. R and R are individually selected from the group consisting of hydroxy, amino, hydrogen, alkyl containing one to five carbon atoms, alkoxy containing one to five carbon atoms and aryl containing up to 20 carbon atoms; salts of such compounds; mixtures thereof and wherein at least one of R and R is hydroxy or amino.

16. A photographic emulsion as in claim 15 wherein said silver halide developing agent is present in a concentration of 0.01 to 5 moles of said developing agent per mole of said photographic silver salt.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 5 Dated ctober 26L 1971 Inventor) Edwin N. Oftedahl Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- In Column 3 line 68 "accordingly" should read :1

according-"p In Column 4, line 26, after are as-- should be inserted.

In Column 4, line 55, that part of formula reading "=COOH" should read COOH In Column 5, line 35, after "6-hydroxy-S,7-dimethoxy" should be inserted -coumarin;--.

In Column 5, line 43, '6-amino" should read 6- hydroxy-.

In Column 5, line 67, "R should be deleted.

In Column 6, line 20, "agents" should read ---agent precursors---.

In Column 6, line 24, "agent precursors" should read --agents (12/10/70 amendment, page 1, under IN THE SPECIFICA TION; the Patent Office erroneously amended line 5 instead of line 9) In Column 6, line 54, "An" should read Any- In Column 7, line 38, that part of formula reading "dimethy" should read dimethyl- In Column 7, line 60, after "coumarins", should be inserted.

In Column 7, line 70, "sliver" should read silver Po-1o50 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated October 26, 1971 Patmu No. ,521

Inventr(s) N. Oftedahl, Jr.

in the above-identified patent It is certified that error appears corrected as shown below:

and that said Letters Patent are hereby F- In Column 8,

---terephthalate--.

line 30, "terephthanlate" should read In Column 9, line 19, after "Russell", should be inserted.

In Column 12, line 2, "variable" should read variables.

In the Claims:

In Column 15, line 11, after "five carbon atoms" should be inserted alkoxy containing 1 to 5 carbon atoms (12/10/70 amendment, page 2, Claim 46(c) Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer ROBERT GOTTSCHALK Commissioner of Patents

Claims

2. An element as in claim 1 also comprising a photographic silver salt layer.
3. An element as in claim 1 also comprising a second silver halide developing agent.
4. An element as in claim 1 wherein said silver halide developing component is Beta ,4-dimethyl-2,5-dihydroxy cinnamic acid.
5. A photographic element comprising a support, photographic silver halide and 2,5-dihydroxy cinnamic acid or 2-hydroxy-5-amino cinnamic acid silver halide developing agent.
6. A photographic-processing composition comprising an alkaline development activator and a 2,5-dihydroxy cinnamic acid or a 2-hydroxy-5-amino cinnamic acid silver halide developing agent.
7. A photographic-processing composition as in claim 6 also comprising a silver halide solvent.
8. A photographic-processing composition as in claim 6 also comprising a second silver halide developing agent.
9. A photographic-processing composition as in claim 6 wherein said silver halide developing agent is an auxiliary developing agent.
10. A photographic-processing composition as in claim 6 wherein the pH of the developer composition is about 10 to about 14.
11. A photographic processing composition as in claim 6 wherein said silver halide developing agent is present in a concentration of 0.01 to 10 percent by weight of said processing composition.
12. A photographic processing composition comprising an alkaline development activator and a coumarin developing agent precursor of the formula:
13. A photographic-processing composition as in claim 12 wherein said developing agent precursor is present in a concentration of 0.01 to 10 percent by weight of said processing composition.
14. A photographic processing composition comprising an alkaline development activator and Beta ,4-dimethyl-2,5-dihydroxy cinnamic acid.
15. A photographic emulsion comprising a photographic silver salt and a lactone derivative silver halide developing agent which is selected from the group consisting of cinnamic acid developing agents of the formula:
16. A photographic emulsion as in claim 15 wherein said silver halide developing agent is present in a concentration of 0.01 to 5 moles of said developing agent per mole of said photographic silver salt.