US3615535A - Photographic element product composition and process - Google Patents

Abstract

In a photographic diffusion transfer system a hydroquinone silver halide developing agent, containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus, provides reduced stain as well as improved maximum density, desired black tone, without loss of other desired sensitometric properties. Such developing agents, e.g. 6(2,5-dihydroxytolyl) hexanoic acid, are especially useful in a black and white silver salt diffusion transfer process. They can be incorporated in a photographic element and can be employed in combination with other silver halide developing agents.

Description

United States Patent James G. Smith;

Dorothy J (Beavers, both of Rochester, N.Y. 20,790

Mar. 18, 1970 Oct. 26, 1971 Eastman Kodak Company Rochester, N.Y.

Inventors Appl. No. Filed Patented Assignee PHOTOGRAPHIC ELEMENT, PRODUCT,

[ References Cited UNITED STATES PATENTS 3,246,016 4/1966 Downey et al. 96/29 3,345,166 10/1967 Land et al 96/29 Primary Examiner Norman G. Torchin Assistant Examiner.lohn L. Goodrow Allorneys-R. E. Knapp, W. H. .l. Kline and B. D. Wiese ABSTRACT: In a photographic diffusion transfer system a hydroquinone silver halide developing agent, containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus, provides reduced stain as well as improved maximum density, desired black tone, without loss of other desired sensitometric properties. Such developing agents, e.g. 6(2,5-dihydroxytolyl) hexanoic acid, are especially useful in a black and white silver salt diffusion transfer process. They can be incorporated in a photographic element and can be employed in combination with other silver halide developing agents.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to certain hydroquinone silver halide developing agents and to photographic elements, processing compositions, and to processes and photographic products, especially diffusion transfer systems, employing such developing agents. In one of its aspects it relates to a photographic product containing a photographic element, a processing composition and an image receiver, in which product the described silver halide developing agents are useful. In another of its aspects it relates to a diffusion transfer process, especially a black and white silver salt diffusion transfer process, employing the described hydroquinone silver halide developing agents.

2. Description of the Prior Art The processing composition usually contains a silver halide solvent such as sodium thiosulfate which causes the unexposed silver salts usually silver halide to dissolve forming a silver complex which diffuses to the image receiver or precipitating layer where development nuclei for an image precipitating agent in that layer causes the silver to be precipitated from the silver complex imagewise. Development nuclei or precipitating agents can be present in the imagereceiving layer before contact with the complex silver or the nuclei can be formed in situ. Diffusion transfer photographic processes, elements and compositions for such processes are well known and described, for example, in U.S. Pat. No. 2,698,237 of Land issued Dec. 28, 1954; U.S. Pat. No. 2,647,056 of Land issued July 28, 1953; U.S. Pat. No. 3,108,001 of Green issued Oct. 22, 1963; and U.S. Pat. No. 3,345,166 of Land issued Oct. 3, 1967.

A processing composition employed in diffusion transfer processes normally contains a developing agent and is usually applied as a viscous fluid layer spread between the photographic layer and the image-receiving layer.

The requirements for developing agents for diffusion transfer systems are very stringent and relatively few of the developing agents which are satisfactory for general silver halide developing processes are satisfactory or sufficiently active for diffusion transfer systems. One of the diffusion transfer developing agents used more successfully is a 2,4- diaminophenol, such as 2,4-diaminophenol-dihydrochloride, also known as Amidol. However, although such developing agents will produce a positive image they are subject to rapid oxidation which results in an unsightly and objectionable dark oxidation product which stains the positive print.

Surprisingly, silver halide developing agents which have been employed successfully in developing silver halide emulsions in general photographic processing have not provided the desired reduction in stain, This is illustrated in the following examples 2,3 and 4 in which it is demonstrated that catechol, 2,4-diaminophenol Amidol and t-butyl hydroquinone silver halide developing agents do not provide a desired reduction in stain, with a black tone image. Moreover, certain other hydroquinone silver halide developing agents are not entirely satisfactory. This is illustrated in example 5.

Accordingly, there has been a continuing need for develop ing agents which provide desired developing action and sensitometric properties in a diffusion transfer system, especially developing agents incorporated in a photographic element, without objectionable stain or oxidation products.

SUMMARY OF THE INVENTION According to the invention, reduced stain, without loss of desired sensitometric properties, and a cold black image tone are provided in a diffusion transfer system, employing photographic products, elements, processing compositions, and processes with a hydroquinone silver halide developing agent containing a methyl. ethyl or alkoxy group, especially methoxy, ethoxy or propoxy, in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms, e.g. carboxypropyl, carboxybutyl or carboxypentyl, in the 2 position of the hydroquinone nucleus.

The hydroquinone silver halide developing agents, as described, are especially suitable in a black and white silver salt diffusion transfer system. Description of the Preferred Embodiments Suitable hydroquinone silver halide developing agents which are employed in the practice of the invention include compounds of the formula:

I 0 z zCH2(CH2)nCO0H R1 wherein R is methyl, ethyl, or alkoxy, especially alkoxy containing l to 5 carbon atoms, e.g. methoxy, ethoxy, propoxy, butoxy or pentoxy; n is 0 to 5; R1 is alkyl containing 1 to 5 carbon atoms, i.e. methyl, ethyl, propyl, butyl or pentyl, hydrogen or halogen, especially chlorine, bromine, or iodine. Examples of such compounds within formula l include:

Z-carboxypropyl-S-methyl hydroquinone 2-carboxybutyl-5-methyl hydroquinone 2-carboxypentyl-5-methyl hydroquinone 2-carboxypropyl-5-ethyl hydroquinone 2-carboxypropyl-5-methoxy hydroquinone 2-carboxypropyl-5'carboxypropyl hydroquinone 2-carboxypropyl-5,6-dimethy1 hydroquinone One embodiment of the invention is: in a photographic product comprising in combination (a) a photographic element comprising a photographic silver halide, (b) a processing composition containing a silver halide solvent and (c) an image-receiving layer, the improvement comprising in said photographic element a hydroquinone silver halide developing agent containing a methyl, ethyl, or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.

Especially suitable hydroquinone developing agents useful in the practice of the invention are those within the scope of the described structure.

The described silver halide location agents can be employed in the practice of the invention in a range of physical locations in a diffusion transfer photographic system. However, they are especially suitable when incorporated in the negative photographic element. The developing agents can be employed, however, in a processing composition employed in such a system if desired. The optimum location will depend upon several factors such as the desired image, processing conditions and the like. For example, the described silver halide developing agents can be employed in a processing composition such as an aqueous alkaline developer solution and/or they can be incorporated into one or more layers of a photographic element such as a photographic silver halide emulsion layer, a layer between the support and the silver halide emulsion layer and/or an overcoat layer. Suitable diffusion transfer systems, processes, processing compositions and elements therefor which can be employed in the practice of the invention are described, for example, in U.S. Pat. No. 2,352,014 of Rott issued June 20, 1944; U.S. Pat. No. 2,452,181 of land issued Feb. 27, 1951; and U.S. Pat. No. 3,337,342 of Green issued Aug. 27, 1967. They can be used in so-called high-speed diffusion transfer processes and compositions therefor as described, for example, in U.S. Pat. No. 3,326,683 of Land et al. issued June 20, 1967 or in other types of diffusion transfer systems, processes and compositions therefor such as described in U.S. Pat. No. 2,857,274 of Land et al. issued Oct. 21, 1958; U.S. Pat. No. 3,020,155 of Yackel et al. issued Feb. 6, 1962; U.S. Pat. No. 2,584,030 of Land issued Jan. 29, 1952; and U.S. Pat. No. 2,923,623 of Land issued Feb. 2, 1960.

These references also describe typical photographic products suitable for diffusion transfer systems comprising in,c ombination (a) a photographic element comprising a photographic silver salt layer such as a photographic silver halide emulsion layer, (b) a processing composition containing a silver halide solvent and typically a silver halide developing agent, e.g. in a rupturable container, and (c) an image receiver.

The developing agents employed in the practice of the invention can be employed for developing an image in a wide range of photographic emulsions. They can be employed in such emulsions if desired.

The silver halide emulsions employed with this invention can comprise silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide, or mixtures thereof. The emulsions can be coarse or fine grain and can be prepared by any of the well-known procedures employed in emulsion making such as single-jet emulsions, double-jet emulsions such as Lippmann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions, such as those described in U.S. Pat. No. 2,222,264 of Nietz et al. issued Nov. 19, 1940; U.S. Pat. No. 3,320,069 of lllingsworth issued May 16, 1967; and U.S. Pat. No. 3,271,157 of McBride issued Sept. 6, 1966. Surface image emulsion can be used or internal image emulsions such as those described in U.S. Pat. No. 2,592,250 of Davey et al. issued Apr. 8, I952; U.S. Pat. No. 3,206,313 of Porter et al. issued Sept. 14, I965; U.S. Pat. No. 3,367,778 of Berriman et al. issued Feb. 6, 1968; and U.S. Pat. No. 3,447,927 of Bacon et al. issued June 3, 1969. If desired mixtures of surface and internal image emulsions can be used as described in U.S. Pat. No. 2,996,382 of Luckey et aI. issued Aug. 15, 1961. Negative type emulsions can be used or direct positive emulsions, such as those described in U.S. Pat. No. 2,184,013 of Leermakers issued Dec. 19, I939; U.S. Pat. No. 2,541,472 of Kendall et al. issued Feb. 13, I951; U.S. Pat. No. 3,367,778 of Berriman et al. issued Feb. 6, 1968; British Pat. No. 723,019 of Schouwenaars; French Pat. No. 1,520,785 published March 4, I968; U.S. Pat. No. 2,563,785 of Ives issued Aug. 7, I951; U.S. Pat. No. 2,456,953 of Knott et al. issued Dec. 21, 1948; and U.S. Pat. No. 2,861,885 of Land issued Dec. 8, I953.

The emulsions used with this invention can be sensitized with chemical sensitizers such as with reducing agents; sulfur, selenium or tellurium compounds; gold, platinum or palladium compounds; or combinations of these.

Suitable procedures for chemical sensitization are described in U.S. Pat. No. 1,623,499 of Sheppard issued Apr. 5, 1967; U.S. Pat. No. 2,399,083 of Waller et al. issued Apr. 23, 1946; U.S. Pat. No. 3,297,447 of McVeigh issued Jan. 10, 1967; and U.S. Pat. No. 3,297,446 of Dunn issued Jan. 10, I967.

The silver halide emulsions, processing compositions and/or image receivers used in the practice of the invention can contain speed increasing compounds such as polyalkylene glycols, cationic surface active agents and thioethers or combinations of these as described in U.S. Pat. No. 2,886,437 of Piper issued May 12, I959; U.S. Pat. No. 3,046,134 of Dann et al. issued July 24, I962; U.S. Pat. No. 2,944,900 ofCarroll et al. issued July 12, 1960; and U.S. Pat. No. 3,294,540 of'Goffe issued Dec. 27, 1966.

The silver halide emulsions and image receivers used in the practice of the invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers each used alone or in combination include thiazolium salts described in U.S. Pat. No. 2,131,038 of Brooker et al. issued Sept. 27, 1938 and U.S. Pat. No. 2,694,716 of Allen issued Nov. 16, 1964; the azaindenes described in U.S. Pat. No. 2,886,437 of Piper issued May 12, 1959 and U.S. Pat. No. 2,444,605 of Heimbach issued July 6, 1948; the mercury salts as described in U.S. Pat. No. 2,728,663 of Allen et al. issued Dec. 27, 1955; the urazoles described in U.S. Pat. No. 3,287,135 of Anderson issued Nov. 22, 1966; the sulfocatechols described in U.S. Pat. No. 3,236,652 of Kennard et al. issued Feb. 22, 1966; the oximes described in British Pat. No. 623,448 published May 19,

I949; nitron; nitroindozoles; the mercaptotetrazoles described in U.S. Pat. No. 2,403,927 of Kendall et al. issued July 16, I946, U.S. Pat. No. 3,266,897 of Kennard et al. issued Aug. 16, 1966 and U.S. Pat. No. 3,397,987 of Luckey et al. issued Aug. 20, 1968; the polyvalent metal salts described in U.S. Pat. No. 2,839,405 of Jones issued June 17, 1958; the thiuronium salts described in U.S. Pat. No. 3,220,839 of Hertz issued Nov. 30, 1965; the palladium, platinum and gold salts described in U.S. Pat. No. 2,566,263 of Trivelli et al. issued Aug. 28, 1951 and U.S. Pat. No. 2,597,915 of Yutzy et al. issued May 27, I952.

The photographic and other hardenable layers employed in a photographic element or image receiver in the process of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as the aldehydes and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfones, active halogen compounds, epoxy compounds. azaindenes, active olefins, isocyanates, carbodiimides, mixed function hardeners and polymeric hardeners such as oxidized polysaccharides like dialdehyde starch, oxyguargum and the like.

The photographic emulsions and elements including image receivers described, employed in the practice of this invention, can contain various colloids alone or in combination as vehicles, binding agents and various layers. Suitable hydrophilic materials including both naturally occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water-soluble polyvinyl compounds like poly(vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers, image receivers and other layers of a photographic element employed in the practice of this invention can also contain, alone or in combination with hydrophilic, water-permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds, such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described, for example, in U.S. Pat. No. 3,142,568 of Nottorfissued July 28, 1964; U.S. Pat. No. 3,193,386 of White issued July 6, I965; U.S. Pat. No. 3,062,674 of Houck et al. issued Nov. 6, I962; U.S. Pat. No. 3,220,844 of Houck et al. issued Nov. 30, 1965; U.S. Pat. No. 3,287,289 of Ream et al. issued Nov. 22, 1966; and U.S. Pat. No. 3,411,911 of Dykstra issued Nov. 19, I968. Particularly effective are those water insoluble polymers of alkyl acrylate and methacrylate, acrylic acid, sulfoalkylacrylates or methacrylates, those which have cross-linking sites which facilitate hardening or curing and those having recurring sulfobetaine units as described in Canadian Pat. No. 774,054.

The photographic elements and image receivers used in the practice of the invention can contain antistatic or conducting layers. Such layers can comprise soluble salts such as chlorides, nitrates and the like, evaporated metal layers, ionic polymers such as those described in U.S. Pat. No. 2,861,056 of Minsk issued Nov. 18, 1958 and U.S. Pat. No. 3,206,312 of Sterman et al. issued Oct. 14, 1965 or insoluble inorganic salts such as those described in U.S. Pat. No. 3,428,451 of Trevoy issued Feb. 18, 1969.

The photographic elements, and/or image receivers and other layers of a photographic element employed and described herein can be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose ester film, poly(vinylacetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film, and related films or resinuous materials, as well as glass, paper metal and the like. Typically a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/or an alpha olefin polymer, particularly a polymer of an alpha olefin containing 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylene-butene copolymers and the like.

The photographic layers and/or image receiver layers employed in the practice of this invention can contain plasticizers and lubricants such as polyalcohols, e.g. glycerin and diols of the type described in U.S. Pat. No. 2,960,404 of Milton issued Nov. 15, 1968; fatty acids or esters such as those described in U.S. Pat. No. 2,588,765 of Robijns issued Mar. 1 1, 1952 and U.S. Pat. No. 3,121,060 of Duane issued Feb. 11, 1964 and silicon resins such as those described in British Pat. No. 955,06 l.

The photographic layers, processing compositions and/or image receivers employed in the practice of this invention can contain surfactants such as saponin, anionic compounds such as alkyl or aryl sulfonates described in U.S. Pat. N 0. 2,600,831 of Baldsiefen issued June 17, 1952 and amphoteric compounds such as those described in U.S. Pat. No. 3,133,816 of Nen-Ezra issued May 19, 1964 and water-soluble adducts of glycidol and an alkyl phenol such as described in British Pat. No. 1,022,878.

The photographic elements and/or image receivers used in the practice of the invention can contain brightening agents including stilbene, triazene, oxazole, and coumarin brightening agents. Water-soluble brightening agents can be used such as those described in German Pat. No. 972,067 and U.S. Pat. No. 2,933,390 of McFall et al. issued Apr. 19, 1960 or dispersions of brighteners can be used, such as those described in German Pat. No. 1,150,274 and U.S. Pat. No. 3,406,070 of Oetiker et al. issued Oct. 15, 1968 and French Pat. No. 1,530,244.

The light-sensitive silver halide emulsions employed in the practice of the invention can be X-ray or other nonspectrally sensitized emulsions. They also can contain spectral sensitizing dyes and be conveniently orthosensitized or pansensitized with such dyes. For instance, these emulsions can be spectrally sensitized by treating with a solution of a sensitizing dye in an organic solvent or the dye can be added in the form of a dispersion as described in British Pat. No. 1,154,781 of Owens et al. For optimum results, the dye may either be added to the emulsion as a final step or at some earlier stage. Sensitizing dyes useful in sensitizing such emulsions are described, for example, in U.S. Pat. No. 2,526,632 of Brooker et al. issued Oct. 24, 1950; U.S. Pat. No. 2,503,776 of Sprague issued Apr. 11, 1950; U.S, Pat. No. 2,493,748 of Brooker et a1. issued .Ian. 10, 1950; and U.S. Pat. No. 3,384,486 of Taber et al. issued May 2 l, 1968. Spectral sensitizers which can be used include the cyanines, merocyanines, complex (trinuclear or tetranuclear) merocyanines, complex (trinuclear or tetranuclear) cyanines, homopolar cyanines, styryls, and hemicyanines, e.g. enamine hemicyanines, oxonols and hemioxonols. The cyanines can contain such basic nuclei as thiazolines, pyrrolines, pyridines, oxazoles, thiazoles, sclenazoles and imidazoles.

Such nuclei can contain sulfoalkyl; carboxyalkyl and alkylamino groups and can be fused to benzene or naphthalene rings either unsubstituted or substituted with halogen, phenyl, alkyl or alkoxy groups. The dyes can be symmetrical or unsymmetrical and can contain alkyl, phenyl or heterocyclic substituents on the polymethine chain. The merocyanine dyes can contain the basic nuclei mentioned as well as acid nuclei such as thiohydantoins, rhodanines, oxazolidenediones, barbituric acids, thiazolineones and malononitrile.

These acid nuclei can be substituted with alkyl, alkylene, phenyl, carboxyalkyl, sulfoalkyl, hydroxyalkyl, alkoxyalkyl, alkylamino groups or heterocyclic nuclei.

Combinations of these dyes can be used, if desired.

In addition, supersensitizing addenda which do not absorb visible light can be included, for instance, ascorbic acid derivatives, azaindenes, cadmium salts, and organic sulfonic acids as described in U.S. Pat. No. 2,933,390 of McFall et al. and U.S. Pat. No. 2,937,089 Of Jones et al. issued May 17, 1960.

The various addenda including sensitizing dyes employed in the practice of this invention can be added to the photographic emulsions and/or other layers of a photographic element and/or image receiver from water solutions or suitable organic solvent solutions. The compounds can be added using various procedures including those described in U.S. Pat. No.

2,912,343 of Collins et al. issued Nov. 10, 1959; U.S. Pat. No. 3,342,605 of McCrossen et a1. issued Sept. 19, 1967; U.S. Pat..,. No. 2,996,287 of Audran issued Aug. 15, 1961 and U.S. Pat. No. 3,425,835 ofJohnson et al. issued Feb. 4, 1969.

The layers of a photographic element and/or image receiver used in the practice of the invention can be coated by various coating procedures including dip coating, airknife coating, curtain coating, or extrusion coating using hoppers of the type described in U.S. Pat. No. 2,681,294 ofBeguin issued June 15, 1954. 11 desired, two or more layers can be coated simultaneously by the procedures described in U.S. Pat. No. 2,761,791 of Russell issued Sept. 4, 1956 and British Pat. N 0. 837,095.

The described developing agents can be employed in color image transfer processes, such as described in U.S. Pat. No. 3,087,817 of Rogers issued Apr. 30, 1963; U.S. Pat. No. 3,185,567 of Rogers issued May 25, 1965; U.S. Pat. No. 2,983,606 of Rogers issued May 9, 1961; and U.S. Pat. No. 3,253,915 of Wyers issued May 31, 1966; U.S. Pat. No. 3,227,550 of Whitmore et al. issued Jan. 4, 1966; U.S. Pat. No. 3,227,551 of Barr et a1. issued Jan. 4, 1966; US. Pat. No. 3,227,552 of Whitmore issued Jan. 4, 1966 as well as U.S. Pat. Nos. 3,415,644; 3,415,645; and U.S. Pat. No. 3,415,646 of Land issued Mar. 10, 1967 and inhibition transfer processes as described in U.S. Pat. No. 2,882,156 of Minsk issued Apr. 14, 1959.

The described developing agents employed in the practice of the invention can be used in colloid transfer processes. They can also be used in photographic elements and/or in processing compositions 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. published Mar. 30, 1967.

The described developing agents employed in the practice of the invention can also be used in multilayer, single element diffusion transfer systems which utilize undeveloped silver halide in nonimage areas of a negative to form a positive by physical development of this silver onto a nuclei-containing, contiguous, image-receiving layer after which the upper layer is removed by scrubbing, washing, stripping or other suitable methods. Processes of this type are described, for instance, in U.S. Pat. No. 3,020,155 of Yackel et al. issued Feb. 6, 1962. Good results are obtained in elements of this type when they are processed by use of a so-called external processing web containing the described developing agents in combination with a silver halide solvent and other processing or coating components dispersed in a vehicle and coated on a suitable support.

Processing webs of this type are described, for example, in U.S. Pat. No. 3,179,517 ofTregillus et al. issued Apr. 20 1965.

The developing agents employed in the practice of the invention can be employed if desired in photographic elements designed for stabilization type processing. For example, they can be incorporated in one or more layers of a photographic element which is exposed, and then processed by contact with an alkaline development activator, and followed by stabilization with a suitable stabilizer such as a thiocyanate or thiosulfate stabilizer, e.g. by contact with a thiocyanate or thiosulfate solution containing ammonium thiocyanate or sodium thiosulfate. Such processes are described, for example, in U.S. Pat. No. 3,326,684 of Nishio et al. issued June 29 1967; British Pat. No. 1,004,302 of llford published Sept. 15, 1965; French Pat. No. 1,516,556 of Fassbender; and in an article by H. D. Russell et al. in P.S.A. Journal, Volume 8, No. 50, pages 59-62, entitled Stabilization Processing of Films and Papers.

The developing agents employed in the practice of the invention can also be present in one or more layers of a photographic element designed for recording color images. For example, these compounds can be employed in one or more layers of the photographic element containing a photographic layer sensitive to the blue region of the spectrum, a photo graphic layer sensitive to the green region of the spectrum, and a photographic layer sensitive to the red region of the spectrum. 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 the developing agents of the invention can be used are described, for example, in Mees, The Theory of the Photographic Process, Third Edition, pages 382-396 (1966).

The developing agents employed in the practice of the invention can be employed in an element containing development nuclei or silver precipitating nuclei, such as an image receiver. As described, they can also be employed in photographic elements and/or processing compositions designed for use with an image receiver.

Development nuclei or silver precipating agents which can be employed in diffusion transfer systems, as described, can be physical development nuclei or chemical precipitants including, for example: (a) heavy metals in colloidal form and salts of these metals, (b) salts of amines which form silver salts and/or (c) nondiffusing polymeric materials with functional groups capable of combining with silver amines.

Suitable development nuclei and/or silver image precipitating agents within the described classes include metal sulfides, selenides, polysulfides, polyselenides, thiourea and its derivatives, stannous halides, sulfur, gold, platinum, palladium, and mercury, colloidal sulfur, aminoguanidine sulfate, aminoguanidine carbonate, arsenous oxide, sodium stannite, hydrazines, xanthates and similar agents disclosed, for example, in U.S. Pat. No. 3,020,l55 of Yackel et al. issued Feb. 6, 1962. A nondiffusing polymeric silver precipitant or development nuclei, such as poly(vinylmercaptoacetate) can also be employed.

A wide range of concentration of development nuclei or silver precipitating agents can be employed. A concentration of the development nuclei or silver precipitant in the image receiving layer must be at least sufficient to insure the development ofa positive image and sufficient removal of undeveloped silver salt from the light-sensitive layer to be processed. Usually the concentration of the developing agents, as described, is about 320 milligrams per square foot of the layer containing the precipitants or development nuclei.

The development agents employed in the practice of the invention can be employed in combination with other silver halide developing agents. The developing agents employed in the practice of the invention can be employed in such combinations as auxiliary developing agents or as the main component of the developing agent combination. Suitable silver halide developing agents which can be employed in combination with the described developing agents include, for example, polyhydroxybenzenes such as hydroquinone developing agents, e.g. hydroquinone, tertiary butyl hydroquinone; catechol and pyrogallol; chloro substituted hydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxy substituted hydroquinones such as methoxyhydroquinone or ethyoxyhydroquinone; aminophenol developing agents such as 2,4-diaminophenols and methoxy aminophenols, methylaminophends; eq. 6-methoxy- 2,4 -diaminophenolascrobic acid developing agents such as ascorbic acid, ascorbic acid ketals, and ascorbic acid derivatives such as those described in U.S. Pat. No. 3,337,342 OfGreen issued Aug. 22, 1967; hydroxylamine developing agents such as N,N-di(2- ethoxyethyl)hydroxylamine; 3-pyrazolidone developing agents such as l-phenyl-3 3-pyrazolidone and l-phenyl-4- hydroxymethyl-3-pyrazolidone, including those described in British Pat. No. 930,572 published July 3, 1963. Such developing agents can be used alone or in combination. It is usually desirable to use other developing agents than aminophenol compounds because of the tendency of these compounds to cause undesired stain.

The described developing agents are especially useful in combination with a reductone silver halide developing agent, especially an anhydro dihydro amino reductone silver halide developing agent. A range of reductone silver halide developing agents can be employed in the practice of the invention. These include any reductone silver halide developing agents which provide desired developing activity and reduction of stain without adversely afiecting desired maximum density, minimum density, photographic speed, gamma and other desired sensitometric properties. A suitable method for preparing the described amino hexose reductones and anhydro amino hexose reductones is set out in U.S. Pat. No. 2,936,308 of Hodge issued May 10, 1960. Corresponding anhydro dihydro amino reductones can be prepared from corresponding anhydro amino reductones by a process of hydrogenation in the presence of a suitable catalyst such as Raney nickel. This is described, for example, in Tetrahedron, Volume 6, pages l23-l38 (1959). Especially suitable reductone silver halide developing agents are anhydro dihydro piperidino hexose reductone, anhydro dihydro pyrrolidino hexose reductone; and anhydro dihydro morpholino hexose reductone.

A variety of cinnamic acid silver halide developing agents can be employed in combination with the described silver halide developing agents in the practice of the invention. Suitable cinnamic acid developing agents include, for example:

Beta-4-dimethyl-2,S-dihydroxy cinnamic acid 4-methyl-2,5-dihydroxy cinnamic acid 6-bromo4-methyl-2,S-dihydroxy cinnamic acid 2-hydroxy-5-amino cinnamic acid Beta-methyl-2-hydroxy-4-methoxy-5-amino cinnamic acid Beta-4-dimethyl-Z-hydroxy-S-amino cinnamic acid Beta-metyl-2,5-dihydroxy-4-methoxy cinnamic acid 2-hydroxy-5-methylamino cinnamic acid 2-hydroxy-5-anilino cinnamic acid 4-! -butyl-2,5-dihydroxy cinnamic acid 2,5-dihydroxy cinnamic acid 2,5-dihydorxy-3,4,6-trimethyl cinnamic acid 2,3-dihydroxy cinnamic acid Cinnamic acid silver halide developing agents in a diffusion transfer system are described, for example, in U.S. application Ser. No. 764,301 ofOftedahl filed Oct. l, 1968.

Typically the described cinnamic acid silver halide developing agents are derived from corresponding hydroxycoumarin and/or aminocoumarin developing agent precursors.

Suitable aminocoumarin and/or hydroxycoumarin developing agents or developing agent precursors which can be employed in the practice of the invention include, for example:

4,7-dimethyl-6-hydroxy coumarin 8-hydroxy coumarin 6-hydroxy-5,7-dimethoxy coumarin 6-hydroxy-5,7-diethoxy-4-methyl coumarin 6-hydroxy coumarin 8-hydroxy- 4-methyl coumarin 6-hydroxy- 4-methyl coumarin 6-hydroxy coumarin-S-sulfonic acid 6-hydroxy coumarin-S-sulfinic acid 4,7,8-trihydroxy coumarin 5 ,6,7trihydroxy-4-methyl coumarin 6,7,8-trihydroxy-4methyl coumarin 5 ,6,7-trihydroxy-4-phenyl coumarin 4,6-dihydroxy coumarin 5,6-dihydroxy coumarin 6,7-dihydroxy coumarin 7,8-dihydroxy coumarin 7-( benzyloxy)-6-hydroxy coumarin 3,8-dibromo-6,7-dihydroxy-4-metyl coumarin 5 ,6-dihydroxy-4,7-dimethyl coumarin 7,8-dihydroxy-3,4-dimethyl coumarin 6,7-dihydroxy-4-methyl coumarin 7,8-dihydroxy-4-methyl coumarin 6,7-dihydroxy-4-methyl-3-phenyl coumarin 6,7-dihydroxy-4-phenyl coumarin A variety of pyrimidine silver halide developing agents can also be employed in the practice of the invention in combination with the described silver halide developing agents. Suitable pyrimidine silver halide developing agents include, for example:

4-amino-5,6-dinydroxy-2-methylpyrimidine 2,5-dihydroxy-4,tS-dimethylpyrimidine 9 2-amino-4,S-dihydroxypyrimidine 2-piperidino-4,5-dihydroxy-6-methylpyrimidine 2,4-diamino-5-hydroxy-6-ethylpyrimidine 2,4-diamino-S-hydroxypyrimidine 2,5-diamino-4,o-dihydroxypyrimidine 2,4-dihydroxy-5,6-diaminopyrimidine 2,4,6-trihydroxy-S-diaminopyrimidine 2,4,5,6-tetrahydroxypyrimidine 2-methyl-4-amino-5,fi-dihydroxypyrimidine 2-amino-4,5-dihydroxy-6-methylpyrimidine 2,4,5-trihydroxy-6-methylpyrimidine 2,4,5-triaminopyrimidine Pyrimidine silver halide developing agents are described,

for example, in an article by R. W. Henn and S. V. Carpenter, Photographic Science and Engineering, No. 3, May-June, pages 135-139 (1959). Pyrimidine silver halide developing agents can be prepared, for example, by reacting the parent pyrimidine compound with a persulfate compound such as ammonium persulfate to produce a S-pyrimidyl hydrogen sulfate compound which can be hydrolyzed with acid such as concentrated hydrochloric acid to form a pyrimidine silver halide developing agent such as a S-hydroxypyrimidine.

Another embodiment of this invention is a photographic element comprising a support, photographic silver halide, and a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of hydroquinone nucleus, as described. An especially suitable hydroquinone developing agent is one of formula I, as described.

Another embodiment of the invention is in a photographic processing composition comprising (a) a silver halide solvent and (b) a silver halide developing agent, the improvement comprising a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus, as described. This composition is especially suitable when an anhydro dihydro reductone silver halide developing agent, as described, is also employed in the composition. A cinnamic acid silver halide developing agent, a coumarin silver halide developing agent or developing agent precursor can also be employed in the described combination of developing agents in the processing composition.

This processing composition is typically employed in a combination of (a) a photographic element comprising a photographic silver salt, especially photographic silver halide, (b) a viscous processing composition comprising:

1. a silver halide solvent,

2. an alkaline development activator, and

3. a silver halide developing agent, and (c) an image receiving layer comprising development nuclei, especially palladium development nuclei, dispersed in a polymeric binder, wherein the improvement comprises employing a hydroquinone developing agent, as described, especially a hydroquinone developing agent of formula I in the photographic element.

Good results are obtained when the described hydroquinone developing agents according to the invention are employed in combination with an amino alkyl hydroquinone silver halide developing agent. The amino alkyl hydroquinone silver halide developing agent is especially suitable when incorporated in the described photographic element. Amino alkyl hydroquinone silver halide developing agents which are suitable in the practice of the invention include, for example, aminomethyl hydroquinone silver halide developing agents of the formula:

wherein R R R and R are each hydrogen; alkoxy, especially alkoxy containing 1 to 5 carbon atoms, such as methoxy, ethoxy, propoxy, butoxy or pentoxy; alkyl, especially alkyl containing 1 to 5 carbon atoms, such as methyl, ethyl, propyl, butyl or pentyl; or aminomethyl, i.e.

wherein R and R are each hydrogen, alkyl, especially alkyl containing l to 5 carbon atoms, as described, aryl containing 6 to 20 carbon atoms, such as phenyl, tolyl and xylyl or together are atoms completing a heterocyclic nucleus, especially a 5 or 6 atom heterocyclic nucleus such as morpholino, piperazino, piperidino, pyrrolidino, 4-methyl piperidino and the like; at least one of R R R, and R is aminomethyl as described.

Corresponding amino alkyl catechol silver halide develop ing agents are also suitable in combination with the described hydroquinone silver halide developing agents in the practice of the invention. These include compounds corresponding to the described hydroquinone compounds of formula ll wherein the hydroxy groups are in the ortho position rather than the para position.

Suitable aminomethyl hydroquinone silver halide developing agents which can be employed in the practice of the invention include, for example:

2-methyl-S-morpholinomethyl hydroquinone 2-methyl-5-pyrrolidinomethyl hydroquinone 2-methyl-S-piperidinomethyl hydroquinone 2-morpholinomethyl hydroquinone The described aminomethyl hydroquinone compounds can be prepared by a Mannich base condensation reaction, such as described in Journal of Organic Chemistry, Volume 29, pages 2640- (l964). Another method of preparing these compounds is described, for example, in Canadian Pat. No. 766,263 issued Aug. 29, l967.

The described developing agents employed in the practice of the invention are typically employed in the form of their salts, such as their acid salts, e.g. their chloride, sulfate or hydrochloride salts or alkali metal salts such as their sodium or potassium salts. The described developing agents can be employed in their salt form or in their salt-free form in the practice of the invention.

A processing composition employed in the practice of the invention is typically a viscous processing composition. A wide range of viscosity can be employed. The viscosity can be about 20 to about 100,000 centipoise, typically about to about 10,000. Various thickening agents are suitable in the described processing compositions and processes of the invention. Any of those commonly employed in diffusion transfer photographic systems can be employed, as well as those employed in viscous monobaths. These include those described, for example, in U.S. Pat. No. 3,120,795 of Land et al. issued Feb. ll, I964, e.g. hydroxyethyl cellulose and carboxymethyl cellulose.

Suitable viscous monobaths in which the described developing agents can be employed are set out, for example, in The Monobath Manual by Grant M. Haist (I966), and U.S. Pat. No. 3,392,0l9 ofBarnes et al. issued July 9, 1968.

A wide range of silver halide solvents can be employed in the practice of the invention. Usually the silver halide solvent is sodium thiosulfate, however, various organic silver halide complexing agents, such as those described in Haist et al., Photographic Science and Engineering, Volume 5, page 198 (1961) and those described in French Pat. No. l,3l2,687 issued Nov. 12, 1962 and Belgian Pat. No. 606,559 of Ulrich et al. issued July 26, 1960 and similar agents can be also be used.

Another embodiment of the invention is in a photographic diffusion transfer process comprising developing a latent image in a photographic silver halide layer and precipitating an image in an image receiver layer, the improvement comprising developing the latent image with a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus, as described. A photographic diffusion transfer process according to this embodiment is typically one wherein the hydroquinone silver halide developing agent is a compound of formula I, as described. This photographic difiusion transfer process is typically a black and white silver salt difiusion transfer process.

The process is carried out at a PH which activates the described developing agents. The activating pH is usually about 10 to about 14 with good results being obtained when the pH is above about 12. When the pH of the system is lowered to less than about 8, such as between about 8 and about 2, developing activity stops. The optimum pH for any particular diffusion transfer system will be influenced by the particular photographic element, the desired image, various addenda employed in the processing composition, emulsion and image receiver, processing conditions and the like.

Any development activator can be employed with the described developing agents which provides the desired pH. Typically development activators which are employed are alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide or lithium hydroxide; however orgaNic development activators can be employed such as amines, e.g. 2- aminoethanol, 2-methylaminoethanol, 2- dimethylaminoethanol, S-diethylamino-2-pentanol and the like.

A photographic process according to the invention can comprise the steps of exposing a photographic element comprising a photographic silver salt, especially a photographic silver halide, and a hydroquinone silver halide developing agent as described, to form a latent image in the photographic element; developing the latent image with a processing composition, at a pH of about 12 to about 14; contacting undeveloped silver salts in the photographic element with a silver halide solvent to form an imagewise distribution of a silver complex in the unexposed areas of the photographic element; transferring at least part of this silver complex to an image receiver contiguous to the photographic silver salt; reducing the silver complex in the presence of development nuclei, especially palladium development nuclei, to form a visible image on the receiver layer; and lowering the pH of the receiver layer to below about 8 to form a stable developed image.

Processing conditions, time of development and the like can vary depending upon various factors such as the desired image, the particular components of the described photographic element, processing composition and image receiver. Typical processing is carried out under normal atmospheric conditions and is completed within about 60 seconds, e.g. within about 10 seconds. Processing temperatures are typically about 20 C. to about 30 C. but elevated temperatures can be employed if desired such as temperatures up to about 90C.

The described photographic element, receiving layer and/or processing composition can also contain toning agents. Typical toning agents which can be employed include, for example, polyvalent inorganic salts as described in US. Pat. No. 2,698,236 of Land issued Dec. 28, 1954; silica as described in US. Pat. No. 2,698,237 of Land issued Dec. 28, I954 and heterocyclic mercaptans such as mercaptoazoles, e.g. mercaptodiazoles, mercaptotriazoles, mercaptotetrazoles, and the corresponding selenoazoles.

The photographic elements, processing conditions and/or image receivers employed in the practice of the invention can contain antioxidants, such as aldehydes-bisulfite condensation products, e.g. sodium formaldehyde-bisulfite.

Also the image receiver can contain an acid, especially a polymeric acid, which can provide lower pH in the image receiver after processing.

The concentration of developing agents used in the practice of the invention can vary over wide ranges depending upon the particular photographic and physical variables in the system. For example, the location of the developing agent in the system, the photographic element, processing composition, the desired image, processing conditions and the like will determine a suitable concentration range. Typically, when a developing agent according to the invention is employed in the photographic element a concentration of about 0.0l to about 5 mols of developing agent per mol of silver present is employed. This usually corresponds to about l0 to about grams of developing agent per mol of silver or about 10 to about milligrams of developing agent per square foot of support. When a developing agent as described is employed in the processing composition, the total concentration of developing agents in the composition is typically about 0.01 percent to about 10 percent preferably about 1 percent to about 5 percent by weight of the total processing composition.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 This illustrates the invention.

A gelatin solution containing 66(2,5-dihydroxytolyl) hexanoic acid, also known as Z-carboxypentyl- S-methyl hydroquinone, is coated on a polyethylene coated paper support at 240 milligrams of gelatin per square foot and 50 milligrams of 6(2,5 dihydroxytolyl) hexanoic acid per square foot. OVer this is coated a coarse grain silver bromoiodide gelatinpolymer emulsion containing 5 mol percent iodide at milligrams of silver per square foot, 320 milligrams of gelatin per square foot and 200 milligrams of a copolymer of butyl acrylate with acrylic acid containing 90 percent by weight butyl acrylate and I0 percent by weight acrylic acid.

A processing composition is prepared by mixing the following components:

(Natrusol ZSOH. sold by Hercules Powder Co., U.S.A.) Water to l liter An image receiver is prepared by coating a water-resistant paper support with palladium development nuclei dispersed in a polymeric binder. The described photographic element is sensitometrically exposed. The processing composition, as described, is then squeezed between the photographic element and the image receiver and the resulting so-called sandwich is pressed together by running between two rollers. After 30 seconds, the so-called sandwich is peeled apart and the resulting image on the image receiver is observed.

Employing this procedure and the described photographic element, processing composition and image receiver, a good positive image is produced, on the receiver having a maximum density of 1.54, a minimum density of 0.0, a cold black tone and no stain. The relative speed of the image is compared to a control rated at 100 at which the same negative element, processing composition and image receiver are employed with the exception that t-butyl hydroquinone is employed in place of 6(2,5-dihydrozytolyl) hexanoic acid.

EXAMPLE 2 This is a comparative example.

The procedure set out in example 1 is repeated with the exception that catechol is employed in place of 6(2,5-dihydroxytolyl) hexanoic acid. The resulting image is vary light, i.e. almost no image is developed. The receiver has a pink stain.

EXAMPLE 3 This is a comparative example.

The procedure set out in example I is repeated with the exception that 2,4-diaminophenol dihydrochloride (Amidol) is employed in place of 6(2,5-dihydroxytolyl) hexanoic acid. The resulting image has very low maximum density and has slight gray stain.

EXAMPLE 4 This is a comparative example.

The procedure set out in example 1 is repeated with the exception that t-butyl hydroquinone is employed in place of 6(2,5-dihydroxytolyl) hexanoic acid. This is the same as the control noted in example l.The resulting image has a maximum density of 1.50 and cold black tone but has slight gray stain.

EXAMPLE 5 This is a comparative example. The procedure set out in example I is repeated with the exception that a hydroquinone compound of the formula:

CHgCHgCHgCOOH is employed in place of 6(2,5-dihydroxytolyl) hexanoic acid. The resulting images has a warm tone, poor stain and minimum density is significantly higher.

EXAMPLE 6 The procedure set out in example I is repeated with the exception that Z-methyl- S-morpholinomethyl hydroquinone is employed in place of 6(2,5 dihydroxtolyl) hexanoic acid in the negative element and I0 grams of a hydroquinone compound of the formula:

also shown as Z-carboxypropyl- S-methyl hydroquinone is employed in the described processing composition.

The resulting image has a maximum density of L45, minimum density of 0.0, and cold black tone.

EXAMPLE 7 EXAMPLE 8 The procedure set out in example 1 is repeated with the exception that 2-methyl- S-morpholinomethyl hydroquinone is employed in place of 6(2,5-dihydroxytolyl) hexanoic acid in the negative element and 5 grams of Z-carboxypentyl- 5- methyl hydroquinone and 5 grams of anhydro dihydro piperidino hexose reductone are employed in the described processing composition.

The resulting image on the image receiver has a maximum density of 1.68, a minimum density of 0.0, cold black tone and no stain.

EXAMPLE 9 Similar results are obtained to those set out in example 8 employing 2-carboxypropyl- S-methyl hydroquinone in place of 2-carboxypentyl- 5-methyl hydroquinone. An in crease in relative speed is observed using a carboxyalkyl group containing two less carbon atoms, i.e. carboxypropyl compared to carboxypentyl.

EXAMPLE 10 Similar results to those set out in example 1 are obtained employing 2-carboxypropyl- S-methyl hydroquinone in place of 6(2,5-dihydrozytolyl) hexanoic acid.

EXAMPLE 1 1 Similar results to those set out in example 1 are obtained employing 2-carboxybutyl- S-methyl hydroquinone in place of 6(2,5-dihydroxytolyl) hexanoic acid.

EXAMPLE 12 Similar results to those set out in example 1 are obtained employing Z-carboxypropyl- 5,6-dimethyl hydroquinone in place of 6(2.5-dihydroxytolyl) hexanoic acid.

EXAMPLE l3 A photographic element is prepared as described in example l with the exception that the 6(2,5-dihydroxytolyl) hexanoic acid is employed in the photographic silver halide emulsion. Similar results are obtained.

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 effected within the spirit and scope of the invention.

We claim:

1. ln a photographic product comprising in combination (a) a photographic element comprising a photographic silver halide, (b) a processing composition containing a silver halide solvent and (c) an image receiving layer the improvement comprising in said photographic product a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.

2. A photographic product as in claim 1 wherein said hydroquinone silver halide developing agent is a compound of the formula:

l on

5. A photographic product as in claim 1 wherein said hydroquinone silver halide developing agent is 6(2,5- dihydroxytolyl) hexanoic acid.

6. A photographic silver halide emulsion comprising photographic silver halide and a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.

7. A photographic silver halide emulsion as in claim 6 wherein said hydroquinone developing agent is 6(2,5- dihydroxytolyl) hexanoic acid.

8. A photographic element comprising a support. photographic silver halide, and a hydroquinone silver halide developing agent containing a methyl, ethyl, or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.

9. A photographic element as in claim 8 wherein said hydroquinone silver halide developing agent is a compound of the formula:

wherein R is methyl, ethyl or alkoxy containing 1 to 5 carbon atoms; n is to R is alkyl containing 1 to 5 carbon atoms.

10. A photographic element as in claim 8 wherein said hydroquinone silver halide developing agent is 6(2,5- dihydroxytolyl) hexanoic acid.

11. In a photographic processing composition comprising (a) a silver halide solvent and (b) a silver halide developing agent the improvement comprising a hydroquinone silver halide developing agent containing a methyl, ethyl, or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.

12. A photographic processing composition as in claim 11 wherein said silver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.

13. A photographic processing composition as in claim II which is a monobath.

14. A photographic processing composition as in claim H which is a viscous liquid.

15. In a photographic diffusion transfer process comprising developing a latent image in a photographic silver halide layer and precipitating an image in an image receiver layer, the improvement comprising developing said latent image with a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.

16. A photographic diffusion transfer process as in claim 15 wherein said hydroquinone silver halide developing agent is a compound of the formula:

I OH

wherein R is methyl, ethyl or alkoxy containing 1 to 5 carbon atoms; n is 0 to 5; R is alkyl containing l to 5 carbon atoms,

17. A photographic diffusion transfer process as in claim 15 wherein said hydroquinone silver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.

18. A photographic diffusion transfer process as in claim 15 which is a black and white silver salt diffusion transfer process.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pazgnt, 3 ,615 53S Da ed October 26, 1971 v James G. Smith and Dorothy J. Beavers It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 57, before "Amidol", should be .nserted, and after "Amidol", should be inserted.

Column 2, line 32, "Z-carboxypropyl-S-carboxypropy1" should read 2carboxybutylS-carboxypropyl Column 3, line 24, "emulsion" should read ---emulsions-- Column 5, line 15, "Nen-Ezra" should read --BenEzra-.

Column 6, line 24, "inhibition" should read ---imbibition---. Line 51, after "20", should be inserted.

Column 7, lines 57-58, "methylaminophends; eq. 6-methoxy- 2,4diaminophenolascrobic" should read -e.g. 6methoxy2,4- iiaminophenol, methylaminophenols; ascorbic--. Line 60, "Of" should read --of-- Line 63, "l-pheny1-3 3-pyrazolidone" should read l-phenyl-3-pyrazolidone--. Lines 63-64, "l-pheny1-4- hydroxymethyl-3pyrazolidone" should read 1- phenyl-4-methyl- 4-hydroxymethy1-3-pyrazolidone-.

Column 8 line 27 that part of the formula reading "Bota4-" should read -Beta, 4- Line 28 "Betametyl" should read ---Beta-methy1 Lines 32-33, "2,5-dihydorxy- 3,4,6'trimethyl cinnamic acid" should read 2,5-dihydroxy- 3,4,6-trimethyl cinnamic acid and should be placed on a line separate from and after "2 5-dihydroxy cinnamic acid" Line 62, that part of the formula reading "-4-metyl" should read I-methyl Line 74 that part of the formula reading "dinydroxy" should read --dihydroXy--.

Column 11, line 26, "orgaNic" should read --organic--.

PAGE 2 mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,615 ,535 Dated October 26 1971 ve or) James G. Smith and Dorothy J. Beavers It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

fi r Column 12 line 26 that part of the formula reading "66 should read 6 Line 31, "OVer" should read -Over-- Line 65 "at" (second occurrence) should read -in- Line 68 that part of the formula reading "dihydrozytolyl" should read --dihydroXytolyl-. Line 74, "vary" should read --very-.

Column 13, line 35, "images" should read ---image--. Line 41, that part of the formula reading "dihydroxtolyl" should read dihydroxytolyl---. Line 54, "shown" should read --known--- Column 14 line 13 "in crease" should read -increase- Line 22 that part of the formula reading "dihydrozytolyl should read --dihydroxytolyl--.

Signed and sealed this 29th day of August 1972.

(SEAL) Attesb:

EDWARD M.P'LETCHER,JR. ROBERT GOTTSCHALK Alltfjfitlll', Officer- Commissionerof Patents

Claims (17)

1. 2. A photographic product as in claim 1 wherein said hydroquinone silver halide developing agent is a compound of the formula:
2. 3. A photographic product as in claim 1 wherein said photographic product comprises an auxiliary silver halide developing agent.
3. 4. A photographic product as in claim 1 wherein said processing composition comprises a silver halide developing agent.
4. 5. A photographic product as in claim 1 wherein said hydroquinone silver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.
5. 6. A photographic silver halide emulsion comprising photographic silver halide and a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.
6. 7. A photographic silver halide emulsion as in claim 6 wherein said hydroquinone developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.
7. 8. A photographic element comprising a support, photographic silver halide, and a hydroquinone silver halide developing agent containing a methyl, ethyl, or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.
8. 9. A photographic element as in claim 8 wherein said hydroquinone silver halide developing agent is a compound of the formula:
9. 10. A photographic element as in claim 8 wherein said hydroquinone silver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.
10. 11. In a photographic processing composition comprising (a) a silver halide solvent and (b) a silver halide developing agent the improvement comprising a hydroquinone silver halide developing agent containing a methyl, ethyl, or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.
11. 12. A photographic processing composition as in claim 11 wherein said silver halide developing agent is 6(2,5-dihydroxytolyl) hexanoic acid.
12. 13. A photographic processing composition as in claim 11 which is a monobath.
13. 14. A photographic processIng composition as in claim 11 which is a viscous liquid.
14. 15. In a photographic diffusion transfer process comprising developing a latent image in a photographic silver halide layer and precipitating an image in an image receiver layer, the improvement comprising developing said latent image with a hydroquinone silver halide developing agent containing a methyl, ethyl or alkoxy group in the 5 position and a carboxyalkyl group containing 4 to 9 carbon atoms in the 2 position of the hydroquinone nucleus.
15. 16. A photographic diffusion transfer process as in claim 15 wherein said hydroquinone silver halide developing agent is a compound of the formula:
16. 17. A photographic diffusion transfer process as in claim 15 wherein said hydroquinone silver halide developing agent is 6(2, 5-dihydroxytolyl) hexanoic acid.
17. 18. A photographic diffusion transfer process as in claim 15 which is a black and white silver salt diffusion transfer process.