US3345170A - Light sensitive photographic elements containing developing agent precursors - Google Patents

Description

United States Patent Ofifice 3,345,170 Patented Oct. 3, 1967 3,345,170 LIGHT SENSITIVE PHOTOGRAPHIC ELE- MENTS CONTAINING DEVELOPING AGENT PRECURSORS Francis J. Evans and John W. Gates, Jr., Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey N Drawing. Filed June 5, 1964, Ser. No. 373,099 20 Claims. (Cl. 96-35) This invention relates to light sensitive photographic silver halide emulsions and more particularly to photographic silver halide emulsions which contain a photographically compatible precursor of a silver halide developing agent.

It is known to incorporate certain silver halide developing agents in photographic silver halide emulsion layers. Such emulsions are developed after exposure to suitable radiation, by treating them in alkaline solutions which may or may not contain a developing agent. Following development, the developed silver image is fixed by treating the developed silver halide layer in a conventional sodium thiosulfate fiXing bath. The :developed and fixed photographic emulsion layer is then washed and dried.

Light sensitive silver halide emulsion layers containing a silver halide developing agent tend to have less stability on storage than is desired.

It is also well known in the photographic art to employ developing agents, the oxidation products of which react with gelatin to raise its melting point, harden or tan it so as to modify its physical properties. The layer can then be subjected to warm water to remove the untanned gelatin in the undeveloped or background areas, leaving a gelatin relief containing a silver image. This gelatin relief, by virtue of the density provided by the silver image, comprises a usable photograph. Alternatively, the difference in absorption between the gelatin relief areas and the background can be used for imbibition of dye solutions for transfer to mordanted receiving sheets; the relief can be used in photochemical processes, such as topography or gravure, the difference in ink-water receptivity of the gelatin relief and the hydrophobic support can be employed in lithographic printing. The relief can be transferred to other supports, such as silk screen for stencil printing and the like. Alternatively, the difference in the ink receptivity of the handened and unhardened areas can be employed directly without wash off as in the lithographic printing process of US. patent application Ser. No. 861,125, filed Dec. 21, 1959.

A process of this kind is also used in colloid transfer systems such as that of US. Patent 2,596,756, issued May 13, 1952.

In the usual process of photographic development, the exposed photographic element comprising a support having at least one gelatin silver halide emulsion layer thereon, is immersed in a developing bath containing a silver halide photographic developing agent. The developing bath is normally maintained as a separate processing bath and with continuous use, the bath usually becomes less efi'icient so that special techniques and replenishments are normally required to maintain optimum processing efficiency. The developing baths of the prior art normally contain a developing agent, a preservative, such as sodium sulfite, and alkali to activate the developing agent, and may also contain other materials, such as sodium bromide (restrainer), antifoggants, etc.

In many processes of the kind mentioned in the foregoing, it has been proposed to incorporate the tanning silver halide developing agent directly in the sensitive emulsion. Although this is convenient, it is frequently disadvantageous because the tanning developing agent in the presence of any oxidant, for example, the oxygen present in the atmosphere may gradually become oxidized sufliciently to tan the gelatin so that the material deteriorates on storage and may become inelfective after some keeping.

We have discovered that silver halide gelatin photographic layers can be coated in a form that is satisfactorily stable to keeping conditions in the presence of atmospheric oxygen even at relatively elevated temperatures and humidities and in a form which can be processed after exposure to a silver image in hardened gelatin against a background of residual silver halide in unhardened water-dispersible gelatin by incorporating the tanning developing agent in the form of a precursor, which is compatible with the silver halide photographic emulsion, with the other normal constituents present in silver halide gelatin emulsion layers. The developer precursor is substantially inert to atmospheric oxygen, but liberates active tanning photographic developing agent on treatment with an alkaline solution having a pH of at least 8.5.

Developer precursors which meet the above conditions are known and are disclosed in our copending U.S. application Ser. No. 251,750, now US. Patent No. 3,287,129. These compounds comprise diene adducts of paraquinones. However, efforts to prepare diene adducts of ortho-quinones have been unsuccessful heretofore because the resulting compounds were unstable. (See Organic Reactions, volume V, page 149, John Wiley & Sons, New York, 1944.) Therefore, it has been desirable to find a method of preparing diene adducts of ortho-qu-inones which could be useful as incorporated developer precursors.

It is therefore an object of our invention to provide silver halide developing agent precursors which can be incorporated with light sensitive silver halide and because of their stability are photographically compatible until the coating containing them is treated with an activating solution that provides a pH that is high enough to cause a conversion of the developing agent precursor to an active developer which will reduce photographically exposed silver halide to silver.

Another object is to provide silver halide photographic materials which have the precursor substances incorporated in the emulsion layers, or layers adjacent thereto. A further object is to provide developing agent precursors for the tanning development of the emulsion layers.

Still another object is to provide a method of processing the emulsion layers of the invention.

The above objects are accomplished by incorporating certain Diels-Alder adducts as developing agent precursors in silver halide emulsion layers, or in layers contiguous thereto, and after photographic exposure, treating 1 with an alkaline solution, such as aqueous sodium carbonate, which treatment causes to be formed an active developing agent in the layers.

The developing agent precursors (Diels-Alder adducts) of our invention are illustrated by the following general formula:

R1 0 a ii 1 X R1 R1 a R1 R2 wherein:

X=-alkylene, e.g. methylene, ethylene R R and R may be alike or different.

The following examples are intended to illustrate our invention but not to limit it in any way.

Example 1.(phenyl-4a,5,8,8a-tatrahydro-i8- methano-I ,Z-naph tltoquinone) To a chilled, stirred solution of 7.2 g. of iodic acid in 280 ml. of water was added dropwise a solution of 18.6 g. (0.1 mole) of 4-phenyl catechol in 280 ml. of acetone. The addition was complete in 1 hour. The brown precipitate which formed was collected by filtration and washed with 50% acetone and water (2X 100 ml. portions). The material was air dried to give 22.4 g. of a brown solid M.P. 104-105 C. which was identified as 4-phenyl-oquinone through its infrared spectrum. This material was converted to its diene adduct in the following manner. To a suspension of 9.2 g. of 4-phenyl-o-quinone in 200 ml. of 30-60 C. petroleum ether was added 6.0 g. of freshly prepared cyclopentadiene. To this suspension, 50 ml. of anhydrous ether was added and the mixture was stirred for 48 hours. The yellow precipitate which had formed during this time was collected and washed several times with 3060 C. petroleum ether and air dried to give 10.7 g. (84.0%) M.P. 121-123 C.

Analysis.-Calcd. for C H O C, 81.6; H, 5.6. Found: C, 81.2; H, 6.0.

Example 2.(4-methyl-4a,5,8,8a-tetrahydr0-5,8- methano-I ,2 -naph thoquinone) To a solution of 6.2 g. (0.05 mole) of 4-methyl catechol in 250 ml. of anhydrous ether were added 35.0 g. of freshly prepared Ag O and 35.0 g. Na SO The mixture was stirred under nitrogen for one hour and then filtered through Celite. To the red filtrate, 5.0 g. (0.05 mole) of cyclopentadiene was added and the solution was stirred for an additional 24 hours. The yellow solution was taken to dryness on a rotary evaporator and the red residue was crystallized with some difiiculty from 60-90 C. ligroin and isopropyl alcohol. The yellow crystalline material was recrystallized several times from petroleum ether and isopropyl alcohol to give 4.5 g. (47.9%) M.P. 79- 80 C.

Analysis.Calcd. for C H O C, 76.6; H, 6.4. Found: C, 76.8; H, 6.7.

Example 3.-(4a,5,8,8a-tetrahydr0-5,8-methano- 1,2-naphthquin0ne) To a stirred, chilled solution of 5.5 g. (.05 mole) of pyrocatechol and 3.3 g. cyclopentadiene in 200 ml. of 80% EtOH was added a solution of 3.6 g. iodic acid in 100 ml. of 80% EtOH. The addition took place over the course of /2 hour. The resulting red solution was stirred vigorously for one hour and stored at 0 C. for 43 hours. The solution was then partially decolorized with Norit and concentrated on a rotary evaporator. The residue was extracted with benzene. The benzene extracts were washed wtih water, dried over anhydrous MgSO and again decolorized with Norit. The solvent was removed under reduced pressure and the residue was crystallized with 6090 C. ligroin and isopropyl alcohol. The yellow solid was recrystallized from isopropanol and 60-90 C. ligroin to give 3.4 g. (39.1%) M.P. 8991 C. The identity of this material was shown by comparison of its infrared spectrum with the spectra of the above two examples.

Example 4 The compound, 4 phenyl 4a,5,8,8a tetrahydro 5,8- :methano-l,2-naphthoquinone, was added as an alcoholic solution to an unhardened fine grained silver chloride photographic emulsion. Coatings were made on a cellulose acetate film support as follows:

(1) Contained 154 mg. Ag/ft 285 mg. gel/ft. and 72 mg. of the naphthoquinone/ftfi.

(2) Contained 195 mg. Ag/ft. 455 mg. gel/ft. and 55 mg. of the naphthoquinone/ftF.

Samples of the coatings were contact exposed to a Kodalith line original, activated for 30 seconds in a 4 percent K CO solution at 68 F., treated 5 seconds in a 2 percent acetic acid stop-bath, fixed in Kodak Fixer F5 and washed in F. water.

In both coatings the non-image areas were washed away whereas the insolubilized image areas adhered to the film base. (1) yielded a silver density of 3.0 and (2) yielded a silver density of 2.0.

The developer precursor compounds of our invention can be incorporated in an ordinary photographic silver halide emulsion, or colloidal dispersion of a water-permeable hydrophilic colloid suitable for preparing an undercoat or an overcoat for such silver halide emulsion, by mixing a solution or dispersion of the precursor compound with the silver halide emulsion, or dispersion of hydrophilic colloid, prior to coating. For example, a developer precursor can be made up as an oil dispersion by stirring a solution of 10 grams of the developing agent precursor into 40 grams of warm tricresyl phosphate, and then mixing this solution with 100 grams of a 10 percent aqueous gelatin solution containing 10 cc. of a 5 percent aqueous solution of an alkylnaphthalene sodium sulfonate wetting agent. The resulting dispersion can then be homogenized by passing for 5 times through a colloid mill to produce a homogeneous colloid dispersion. Solvents other than tricresyl phosphate can be employed, including any of the crystalloidal compounds described in Jelley and Vittum U.S. Patent 2,322,027, issued June 15, 1943. The resulting colloidal dispersion can then be added to an ordinary silver halide emulsion, or a dispersion of a water-permeable hydrophilic colloid, adapted for preparation of an undercoat or overcoat for such silver halide emulsion.

The developing agent precursors of our invention can be adapted for addition to a liquid silver halide emulsion or colloidal dispersion by other means as well. Suitable methods will depend largely upon the solubility characteristics, particularly in water or polar solvents, of the particular precursors in question.

After addition of the dispersion or solution of the developing agent precursor substance to the liquid emulsion or colloidal dispersion, the mixture is stirred to assure uniform results, or passed through a blending device, such as a colloid mill or Waring Blendor. A uniform coating can then be made on a suitable support and the coating dried. Suitable supports comprise any of the well known supporting materials, such as cellulose ester film base (e.g. cellulose acetate, cellulose nitrate, cellulose acetate butyrate, cellulose acetate propionate, etc.), polyethylene, polypropylene, polystyrene, polyethylene terephthalate and other polyesters, paper, polycarbonates, etc.

The photographic elements of our invention comprising a photographic development precursor either in the photographic silver halide emulsion layer, or layer contiguous thereto, or both, can then be exposed to an original or negative and developed by merely treating the exposed emulsion layer with an alkaline activator bath. Typical activator baths comprise, for example, an aqueous solution of an alkaline material, such as sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, mixtures of sodium hydroxide and sodium sulfite, etc. Suitable baths can comprise, for example, an aqueous solution containing about 1 percent sodium hydroxide and 5 percent sodium sulfite. A bath of the latter type is quite suitable for developing an exposed emulsion layer in about 30 seconds when the activator bath is at about 68 F. Modifications can easily be made in the activator baths without departing from the spirit and scope of the invention. For example, an aqueous solution comprising about 4 percent of sodium carbonate and 5 percent of sodium sulfite produces development in about 30 seconds at 68 F. Another aqueous activator solution comprising 2 percent sodium hydroxide and 5 percent sodium sulfite produces useful photographic images in a few seconds when heated at F. Particularly useful activator solutions have a pH of at least about 9.0 and preferably of at least about 10.5.

The activator solutions of the present invention can be applied to an exposed photographic element in any number of known ways, such as by dipping, spraying, or other suitable surface applications. If desired, a thickener can be added to the activator solution to increase the viscosity of the composition and make it more adaptable for continuous processing. Viscous compositions can then be removed by squeegeeing or water spraying. The photographic element can then be stabilized by conventional fixation or stabilization, such as by sodium thiosulfate.

The concentration of the precursors used in our invention will vary, depending upon the particular chemical compound involved and the location of the compound within the photographic element. That is, if the precursor is incorporated within the silver halide emulsion undergoing development, it may be desirable to use a somewhat dilferent concentration than would be used if the precursor were incorporated in a layer contiguous to the photographic silver halide emulsion. A useful concentration of precursor for incorporation in the emulsion is from about 0.005 to 3.0 moles per mole of silver halide. A particularly useful range is from about 0.01 to 1.0 mole per mole of silver halide, with especially useful results being obtained within the range of about 0.02 to 0.6 mole per mole of silver halide. For incorporation in a layer contiguous to the silver halide emulsion layer, somewhat larger concentrations of precursor can be tolerated without adverse efiects.

Photographic silver halide emulsions useful in our invention comprise any of the ordinarily employed silver halide developing-out emulsions, such as, silver chloride, -chlorobromide, -chloroiodide, -chlorobromoiodide, bromide and -bromoiodide developing-out emulsions. Any of the conventionally employed water-permeable hydrophilic colloids can be employed in the silver halide emulsions, or in a layer contiguous thereto. Typical waterpermeable hydrophilic colloids include gelatin, albumin, polyvinyl alcohol, agar agar, sodium alginate, hydrolyzed cellulose esters, hydrophilic polyvinyl copolymers, etc.

Photographic silver halide emulsions useful in 0 ur invention can also contain such addenda as chemical sensitizers e.g. sulfur sensitizers (e.g. allyl thiocarbamate, thiourea, allyl isothiocyanate, cystine, etc.), various gold compounds (e.g. potassium chloroaurate, auric trichloride, etc.). (See U.S. Patents 2,540,085, 2,597,856 and 2,597,915.)

Photographic silver halide emulsions useful in our invention can also be sensitized by other means, such as by alkylene oxide polymers, many of which are well known to those skilled in the photographic art. Typical polyalkylene oxide polymers include those of US. Patents 2,423,549 and 2,441,389.

The emulsions of the invention can also contain speedincreasing compounds of the quaternary ammonium type as described in U.S. Patents 2,271,623, issued Feb. 3, 1942; 2,288,226, issued June 30, 1942; 2,334,864, issued Nov. 23, 1943; or the thiopolymers as described in Graham et al., U.S. application Ser. No. 779,839, filed Dec. 12, 1958; and Dann et al., U.S. application Ser. No. 779,874, filed Dec. 12, 1958.

The emulsions may also be chemically sensitized with reducing agent such as stannous salts (Carroll U.S. Patent 2,487,850), polyamines such as diethylene triamine (Lowe and Jones U.S. Patent 2,518,698), polyamines such as spermine (Lowe and Allen U.S. Patent 2,521,- 925 or bis-(B-aminoethyl) sulfide and its water soluble salts (Lowe and Jones U.S. Patent 2,521,926).

The emulsions may also be stabilized with the mercury compounds of Allen, Byers and Murray U.S. application Ser. No. 319,611; Carroll and Murray U.S. application Ser. No. 319,612; and Leubner and Murray U.S. application Ser. No. 319,613, all filed Nov. 8, 1952, now U.S.

Patents 2,728,663, 2,728,664, and 2,728,665, respectively, granted Dec. 27, 1955.

The addenda which we have described may be used in various kinds of photographic emulsions. In addition to being useful in X-ray and other nonoptically sensitized emulsions, they may also be used in orthochromatic, panchromatic, and infrared sensitive emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. The agents may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color generating materials, emulsions of the mixed-packet type, such as described in Godowsky, U.S. Patent 2,698,- 794, issued Jan. 9, 1955 or emulsions of the mixed-grain type, such as described in Carroll and Hanson U.S. Patent 2,592,243.

It has been found that the development rate of the precursors above can be improved by adding an auxiliary developing agent either to the silver halide emulsion layer, or a hydrophilic layer contiguous thereto. Typical auxiliary developing agents include those described in the copending application Ser. No. 134,014, filed Aug. 5, 1961, of P. H. Stewart, G. E. Fallesen and J. W. Reeves, Jr. Typical auxiliary developing agents described in this application include 3-pyrazolidone compounds containing an alkyl (e.g. methyl, ethyl, etc.) or aryl substituent (e.g. phenyl, p-tolyl, etc.). In addition, such 3-pyrazolidones can be made inert to facilitate incorporation in the emulsion by introducing an acyl or acyloxy substituent which will be hydrolyzed from the compound by treatment with the above activator solutions to produce the desired developing agent. Typical auxiliary developing agents include, for example, 1-phenyl-3-pyrazolidone, 1-p-tolyl-3- pyrazolidone, 1-phenyl-5-methyl-3-pyrazolidone, l-acetamido-phenyl-3-pyrazolidone, l-phenyl-4,4 dimethyl-3- pyrazolidone, 1-phenyl-4-methyl-3-pyrazolidone, etc. Typical inert precursors useful for incorporation include 3- acetoxy-l-phenyl-3-pyrazolidone (Enol ester), Z-(pyridinium acetyl)-1-phenyl-3-pyrazolidone chloride, l-phenyl- 2-benzoyl-3 pyrazolidone, l-phenyl-Z-lauroyl B-pyrazolidone, 1-phenyl-2-chloroacetyl-3-pyrazolidone, etc.

The concentration of auxiliary developing agents can be varied and, of course, no auxiliary developing agent need be employed unless so desired. Useful concentrations of auxiliary developing agent vary from about 0.01 mole to 2.0 moles per mole of the developing agent precursor. Depending upon the particular auxiliary developing agent employed, larger or smaller quantities can be used.

The developer precursors of our invention can be used in emulsions intended for use in diffusion transfer processes which utilize the undeveloped silver halide in the non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott U.S. Patent 2,352,014, issued June 20, 1944, and Land U.S. Patents 2,584,029, issued J an. 29, 1952; 2,698,- 236, issued Dec. 28, 1954, and 2,543,181, issued Feb. 27, 1951; and Yackel et a1. U.S. Patent 3,020,155, issued Feb. 6, 1962. They may also be used in color transfer processes which utilize the difiusion transfer of an image- Wise distribution of developer, coupler or dye, from a light sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land U.S. Patents 2,559,643, issued July 10, 1951, and 2,698,798, issued Jan. 4, 1955; Land and Rogers Belgium Patents 554,933 and 554,934, granted Aug. 12, 1957; International Polaroid Belgium Patents 554,212, granted July 16, 1957, and 554,935, granted Aug. 12, 1957; Yutzy U.S. Patent 2,756,- 142, granted July 24, 1956, and Whitmore and Mader U.S. patent application Ser. No. 734,141, filed May 9, 1958. They may also be used in emulsions intended for use in a monobath process such as described in Haist 7 et a1. U.S. Patent 2,875,048, issued Feb. 24, 1959, and in web-type processes, such as the one described in Tregillus et al. US. patent application Ser. No. 835,473, filed Aug. 24, 1959.

Of course, the activator solutions which are used in our invention are stable for extended periods of time and are not subject to the harmful decomposition reactions so common to conventional photographic developing solutions when these developing solution are stored for extended periods of time. No special precautions are required to prevent oxidation of the activator solutions since they are inherently quite stable. If desired, the ac tivator solutions can be incorporated in a carrier, such as gelatin and coated in contact with the photographic silver halide emulsion layer which contains the development precursors of our invention. After exposure, the development can be effected merely by heating the photographic emulsion layer to a temperature sufiicient to release water, which may be present in the support or in a separate layer in the photographic element. This water then dissolves the activator solution from the hydrophilic colloid layers and takes it into the photographic halide emulsion layer where the development is effected.

The elevated temperatures from about 95l50 C. are usually sufficient to effect development in this manner. If desired, additional moisture can be added by spraying steam upon the sensitive surface of the photographic element.

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 as described hereinabove and as defined in the appended claims.

We claim:

1. A photographic element comprising a support and a photographic silver halide emulsion layer, and integral with said photographic element a water-permeable hydrophilic colloid layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represent-s a member selected from the class consisting of hydrogen, alkyl groups from 120 carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups.

2. A photographic element comprising a support and a photographic water-permeable hydrophilic colloid silver halide emulsion layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 12 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class 8 a o consisting of hydrogen, alkyl groups from 12() carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower. alkyl groups.

3. A photographic element comprising a paper support and a photographic silver halide emulsion layer, and integral with said photographic element a water-permeable hydrophilic colloid layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 1-2. carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups.

4. A photographic element comprising a support with a photographic silver halide emulsion layer, and integral with said photographic element, a colloidal dispersion of a compound in a water-soluble, water-permeable crystalloidal solvent, said compound being selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and R represents a member of a class conssiting of hydrogen and lower alkyl groups.

5. A photographic element according to claim 4 wherein said crystalloidal solvent is a high-boiling ester of a phenol.

6. A photographic element according to claim 4 wherein said high-boiling ester is tricresyl phosphate.

7. A photographic element comprising a paper support and a photographic silver halide emulsion layer, and integral with said photographic element a water-permeable, hydrophilic colloid layer containing (a) a compound selected from the class of compounds represented by the following general formula:

Rs l

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups, and (b) a 3-pyrazolidone photographic developing agent.

8. A photographic element comprising a flexible support and a photographic silver halide emulsion layer, and integral with said photographic element a waterpermeable hydrophilic colloid layer containing a compound selected from the class of compounds represented by the following general formula:

l sl

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group'and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups.

9. A photographic element comprising a support and a photographic silver halide gelatino emulsion layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the the class consisting of alkylene groups having l-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups.

10. A photographic element comprising a support and a photographic silver halide untanned gelatino emulsion layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-2() carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups.

11. A process for forming a visible photographic image com-prising developing an exposed photographic element comprising a support and a photographic silver halide emulsion layer, and integral with said photographic element, a water-permeable, hydrophilic colloid layer con- 1 0 taining a compound selected from the class of-compounds represented by the following general formula:

wherein R represents a member selected from the class consisting of alkylene groups having l-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and F represents a member of a class consisting of hydrogen and lower alkyl groups, by imbibing throughout said photographic silver halide emulsion layer an aqueous alkaline solution containing sufficient alkali to give a pH of at least about 9.0.

12. A process for forming a photoresist comprising exposing a substantially unhardened colloidal photographic silver halide emulsion layer containing a compound selected from the class of compounds represented by the following general formula:

R R3 wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydro-gen, alkyl groups from l-20 carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups, developing in an alkaline bath, and removing the untanned areas in warm water.

13. A photographic process as defined in claim 12 wherein said precursor is 4-phenyl-4a,5,8,8a-tetrahydro- 5,8-methano-1,2-naphthoquinone.

14. A photographic process as defined in claim 12 wherein said procursor is 4-methyl-4a,5,8,8a-tetrahydro- 5,8-methano-1,2-naphthoquinone.

15. A photographic process as defined in claim 12 wherein said precursor is 4a,5,8,8a-tetrahydro-5,8-meth ano-l,2-naphthoquinone.

16. A process for forming a visible photographic image comprising developing an exposed photographic element comprising a support and a gelatino photographic silver halide emulsion layer, and integral with said photographic element, a gelatin layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and R represents a. member of a class consisting of hydrogen and lower alkyl groups, by imbibing throughout said photographic silver halide emulsion layer an aqueous alkaline solution containing sufficient alkali to give a pH of at least about 9.0.

17. A process for forming a photoresist comprising exposing a substantially unhardened gelatino photographic silver halide emulsion layer containing a compound selected from the class of compounds represented by the following general formula:

wherein X represents a member selected from the class consisting of alkylene groups having 1-2 carbon atoms, R represents a member selected from the class consisting of hydrogen, lower alkyl groups, an aryl group and halogen, R represents a member selected from the class consisting of hydrogen, alkyl groups from 1-20 carbon atoms, an aryl group and halogen and R represents a member of a class consisting of hydrogen and lower alkyl groups, developing in an alkaline bath, and removing the untanned areas in warm water.

18. A photographic process as defined in claim 17 wherein said precursor is 4-phenyl-4a,5,8,Sa-tetrahydro- 5,8-methano-1,2-naphthoquinone.

19. A photographic process as defined in claim 17 wherein said precursor is 4-methyl-4a,5,8,8a-tetrahydro- 5,8-methano-1,2-naphthoquinone.

20. A photographic process as defined in claim 17 wherein said precursor is 4a,5,8,8a-tetrahydro-5,8-methano-1,2-naphthoquinone.

References Cited UNITED STATES PATENTS 4/1952 Yackel 9695 8/1955 Yutzy et al. 96-95 OTHER REFERENCES NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner.

Claims (2)

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT AND A PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER, AND INTEGRAL WITH SAID PHTOGRAPHIC ELEMENT A WATER-PERMEABLE HYDROPHILIC COLLOID LAYER CONTAINING A COMPOUND SELECTED FROM THE CLASS OF COMPOUNDS REPRESENTED BY THE FOLLOWING GENERAL FORMULA:

12. A PROCESS FOR FORMING A PHOTORESIST COMPRISING EXPOSING A SUBSTANTIALLY UNHARDENED COLLOIDAL PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER CONTAINING A COMPOUND SELECTED FROM THE CLASS OF COMPOUNDS REPRESENTED BY THE FOLLOWING GENERAL FORMULA: