US3615519A - Direct-positive lithographic elements and processes for developing same - Google Patents

Abstract

Direct-positive-blue-sensitive, chemically fogged, silver halide photographic elements containing an alkylene oxide polymer and a process for developing direct-positive-blue-sensitive, silver halide photographic elements in the presence of a polyhydroxybenzene developer and an alkylene oxide polymer.

Description

United States Patent Inventor Kirby M. Milton Fishers, N.Y.

Appl. No. 758,582

Filed Sept. 9, 1968 Patented Oct. 26, 1971 Assignee Eastman Kodak Company Rochester, N.Y.

DIRECT-POSITIVE LITHOGRAPHIC ELEMENTS AND PROCESSES FOR DEVELOPING SAME 34 Claims, No Drawings US. Cl 96/64, 96/66, 96/114, 96/107 Int. Cl G03c 5/24 Field of Search 96/1 14, 64

References Cited UNITED STATES PATENTS 2,995,444 8/1961 Dersch 96/114 X 3,364,026 1/1968 Rees 96/64 FOREIGN PATENTS 940,051 10/1963 England 96/1 14 945,857 1/i964 England 96/1 14 Primaq: Examiner-Norman G. Torchin Assistant Examiner-John L. Goodrow Anarneys-W. 1-1.]. Kline, Bernard D. Wiese and Gerald E.

Battist ABSTRACT: Direct-positive-blue-sensitive, chemically fogged, silver halide photographic elements containing an alkylene oxide polymer and a process for developing directpositive-blue-sensitive, silver halide photographic elements in the presence of a polyhydroxybenzene developer and an alkylene oxide polymer.

DIRECT-POSITIVE LITHOGRAPHIC ELEMENTS AND PROCESSES FOR DEVELOPING SAME This invention relates to photographic materials, their preparation and use. In one of its aspects, this invention relates to direct-positive-blue-sensitive, lithographic elements. In another aspect, this invention relates to processing directpositive-blue-sensitive, silver halide lithographic elements in the presence of a polyhydroxybenzene developer and an alkylene oxide polymer.

In the graphic arts field, it is desirable to provide improved direct-positive elements and processes for obtaining improved direct-positive lithographic image records. Direct-positiveblue-sensitive, silver halide emulsions, wherein said halide is predominantly chloride, can generally be processed in low sulfite polyhydroxybenzene developers to obtain good directpositive, high-speed, lithographic images. However, it is desirable to improve the photographic properties such as image clarity, speed, development time and contrast of the lithographic image.

In reproducing continuous tone material, it is customary to make a halftone photographic intermediate, usually a film negative, in which the gradations in tone are represented by differing sizes of dots of uniform density. The shape, density and uniformity of the halftone dots are closely correlated to the quality of the resulting picture.

Photographic films used in the graphic arts field for making halftone or line images should be capable of producing extremely high contrast and good image sharpness. These factors contribute in the case of halftone images to high dot quality, that is, to the production of halftone dots of high density and sharpness.

According to this invention, I have now found a system for providing improved direct-positive lithographic records. Highcontrast, direct-positive image records can be obtained by developing blue-sensitive-direct-positive, silver halide compositions in the presence of a polyhydroxybenzene developer and an alkylene oxide polymer. In one preferred embodiment of the invention, a photographic element, comprising a directpositive-blue-sensitive, chemically fogged, silver halide composition and an alkylene oxide polymer, is processed in the presence of a polyhydroxybenzene developer.

According to the process of my invention, exposed, directpositive, high-contrast elements, defined more precisely hereinafter, are developed in the presence of an alkylene oxide polymer. The polymer can be present in the photographic element itself, such as in the silver halide emulsion or in a layer contiguous to the silver halide emulsion, or it can be present elsewhere in the system, such as in the photographic developer composition. The alkylene oxides from which the polymers are derived preferably contain from two to four carbon atoms, e.g., ethylene oxide, propylene oxide and butylene oxide. The preparation of polymers from these compounds is described in Ellis, The Chemistry of Synthetic Resins" (1935 pages 990-994.

While any alkylene oxide polymer or derivative thereof can be employed in this invention, I prefer to use ethylene oxide polymers or derivatives thereof such as polyethylene glycol, polyethylene glycol oleyl ether, polyethylene glycol cetyl ether, etc., in which the ethylene oxide moiety has an average molecular weight of from about 300 to about 4,000 which preferably have 4 or more alkylene oxide units. Another way to define certain preferred ethylene oxide polymers is by the following formula:

wherein n an integer of from about 5 to about 100 and R is hydrogen, an alkyl radical (e.g., ethyl, dodecyl, oleyl), and acid radical (e.g., carboxylic sulfonic, etc.), and acyl radical or an organic carboxylic acid (e.g., lauric acid, oleic acid), or a phenyl radical (e.g., phenyl, p-dodecylphenyl). However, it is understood that the alkylene oxide polymers may also have a highly branched structure or macrocyclic structure.

Polyethylene oxide derivatives are obtained by condensing a polyethylene oxide with compounds containing an active hydrogen atom. Suitable organic compounds with active hydrogen atoms are, for example, alcohols, primary or secondary amines, acids, amides, phenols, etc. Examples of such organic compounds include monohydric saturated or unsaturated alcohols having one to 20 carbon atoms, e.g., ethanol, dodecanol, stearyl alcohol, oleyl alcohol; polyhydric alcohols, e.g., glycols, glycerol, pentaerythritol, trimethylol propane; aliphatic primary or secondary amines, e.g., N-methyl-N- dodecylamine; aliphatic carboxylic acids, e.g., lauric acid, stearic acid, oleic acid or the amides of these acids; phenol or alkyl phenols, e.g., p-dodecyl phenol; and phosphoric acid esters of polyalkylehe oxides of the type described in Belgian Pat. 611,864 of Gevaert issued Dec. 22, 1961, and British Pat. 1,067,958 of Agfa issued May 10, 1967.

Especially good results are obtained when the alkylene oxide polymer is a water-soluble alkylene oxide blockcopolymer containing at least about 10 percent by weight of ethylene oxide units. Particularly useful results are obtained with water-soluble block copolymers of polyoxypropylene and polyoxyethylene. The polyoxypropylene chain or moiety preferably has an average molecular weight between 800 and 3,000 and the polyo'xyethylene units preferably constitute from about 10 to about 70 percent by weight of the polymer. These block polymers are available commercially under the trade name Pluronic, e.g., Pluronic L61, L62, L44, P65, L64, L92 and L81. A further description of these block polymers can be found in U.S. Pat. Nos. 3,294,540 of Goffe issued Dec. 27, 1966, 2,674,619 of Lundsted issued Apr. 6, l954, and 3,022,335 of Lundsted issued Feb. 20, 1962. Water-soluble organosilicone polyalkyleneoxide polymers such as those disclosed in U.S. Pat. No. 2,917,480 of Bailey and O'Connor issued Dec. 15, 1959, can also be employed. These water-soluble alkylene oxide block copolymers preferably contain at least about 30 percent by weight of ethylene oxide units and contain in their main chain up to approximately 15 percent by weight of silicon atoms.

The alkylene oxide polymer can be used in any concentration effective for the intended purpose. When the alkylene oxide polymer is present in the photographic element, good results are obtained when the concentration is less than about 2 grams per mole of silver in the silver halide emulsion. A preferred concentration range for the polymer in this embodiment is from about 10 to about 800 milligrams per mole of silver in the silver halide emulsion. When the alkylene oxide polymer is present in the photographic developer, good results are generally obtained when the polymer is employed in a concentration of from about 0.l to about 10 grams per liter of developer composition.

The photographic developer employed in my invention contains a silver halide developing agent consisting essentially of a polyhydroxybenzene compound. Examples of polyhydroxybenzene compounds are hydroquinone, catechol, pyrogallol, isopropylhydroquinone, methylhydroquinone, 2,5-dimethylhydroquinone, o-chlorohydroquinone, o-bromohydroquinone, 4-phenyl catechol 4-phenethyl catechol, 4-phenpropyl catechol, 4-t-butyl catechol, 4-n-butylpyrogallol, 4,5- dibromocatechol, etc. Esters of such compounds, e.g., formates and acetates, can also be employed. The developer agent can be contained in the element, in the solution or can be supplied from a layer on a separate support.

The developing agent can be employed in any concentration effective for the intended purpose. Generally, good results are obtained when the developer contains from about 12 to about 20 grams of developing agent per liter of developer.

The developer can contain conventional addenda such as antioxidants, e.g., sodium sulfite; alkaline material to produce a p of at least about 9.0, e.g., sodium carbonate. sodium hydroxide, etc., restrainers, e.g., potassium bromide, sodium bromide; sequestering agents, etc. The use of a developer containing a carbonyl bisulfite-amine condensation product, with at least about 0.075 mole of excess free amine per liter of developer composition and a dihydroxybenzene developing agent as disclosed in Masseth, Belgian Pat. 704,595 granted Nov. 14, 1967, is also quite useful in my invention.

in a preferred embodiment of this invention, the developers contain (1) sodium formaldehyde bisulfite or a carbonyl bisulfite amine and (2) from about 0.01 to about 0.05 molar of sulfite ion. Generally this developer has a p" of at least 9.0. The sodium formaldehyde bisulfite can generally be used in the developer in concentrations of about 40 to about 80 grams per liter and is preferably used in combination with an alkali metal sulfite; it can also be formed in situ by employing a mixture of formaldehyde (or paraformaldehyde) and sodium sulfite in the developer.

Useful concentrations of reducing agent and metal compound (e.g., metal salt) can be varied over a considerable raNge. As a general guideline, good results are obtained using about .05 to 40 mg. reducing agent per mole of silver halide, and 0.05 to 15.0 mg. metal compound per mole of silver halide;

As used herein, and in the appended claims, fogged refers to emulsions containing silver halide grains which produce a density of at least 0.5 when developed, without exposure, for 5 minutes at 68 F. in Developer A having the composition set forth below, when the emulsion is coated at a silver coverage of 50 mg. to 500 mg. per square foot.

The direct-positive compositions of this invention are bluesensitive compositions. It is understood that blue-sensitive means that the direct-positive compositions will provide a reversal image when exposed with light in the 350 to 500 millimicron range of the electromagnetic spectrum. The silver halide compositions can also be spectrally sensitized so as to form reversal images when exposed in other regions of the spectrum such as in the green and red regions. However, they all have the property of being capable of forming a reversal image when exposed with light in the blue region of the visible spectrum.

Typical direct-positive silver halide compositions which can be characterized by the above tests and which are useful in this invention are (l) emulsions comprising silver halide grains having internal centers which promote the deposition of photolytic silver and an outer shell or region of a fogged silver halide and preferably a halogen-conducting compound in said emulsion or (2) an emulsion which comprises fogged silver halide grains and an organic compound which accepts electrons, wherein said halide is at least 50 mole percent chloride, said grains being such that a test portion thereof, when coated as a photographic silver halide emulsion on a support to give a maximum density of at least about 1 upon processing for 6 minutes at about 68 F. in Developer A, referred to hereinafter, has a maximum density which is at least about 30 percent greater than the maximum density of an identical coated test portion which is processed for 6 minutes at about 68 F in the same developer after being bleached for about 5 minutes at about 68 F. in a 0.3 percent aqueous potassium ferricyanide solution.

This invention can be practiced with direct-positive emulsions of the type in which a silver halide grain has a water-insoluble silver salt center and an outer shell composed of a fogged water-insoluble silver salt that develops to silver without exposure. These emulsions can be prepared in various ways, such as those described in Berriman US. Pat. No.

3,367,778 issued Feb. 6, 1968. For example, the shell of the grains in such emulsions may be prepared by precipitating over the core grains a light-sensitive, water-insoluble silver salt that can be fogged and which fog is removable by bleaching. The shell is of sufficient thickness to prevent access of the developer used in processing emulsions of the invention to the core. The silver salt shell is surface fogged to make it developable to metallic silver with conventional surface image developing compositions. The silver salt of the shell is suffciently fogged to produce a density of at least about 0.5 when developed for 6 minutes at 68 F. in Developer B below. Such fogging can be effected by chemically sensitizing to fog with the sensitizing agents described for chemically sensitizing the core emulsion, high-intensity light and the like fogging means well known to those skilled in the art. While the core need not be sensitized to fog, the shell is fogged. Fogging by means of a reduction sensitizer, a noble metal salt such as gold salt plus a reduction sensitizer, a sulfur sensitizer, high p and low p silver halide precipitating conditions, and the like can be suitably utilized. The shell portion of the subject grains can also be coated prior to fogging.

Before the shell of water-insoluble silver salt is added to the silver salt core, the core emulsion is first chemically or physically treated by methods previously described in the prior art to produce centers which promote the deposition of photolytic silver, i.e., latent image nucleating centers. Such.

centers can be obtained by various techniques as described in the Berriman Patent 3,367,778 referred to above. Silver salt cores containing centers attributable to a metal of Group Vlll of the Periodic Table, e.g., palladium, iridium or platinum and the like, are especially useful since these centers also appear to function as electron acceptors. Chemical sensitization techniques of the type described by Antoine Hautot and Henri Saubenier in Science et Industries Photographiques, Vol. XX- VIIl, Jan. 1957, pages 1 to 23, and Jan. l957, pages 57 to 65, are particularly useful. Such chemical sensitization includes three major classes, namely, gold or noble metal sensitization, sulfur sensitization, such as by a labile sulfur compound, and reduction sensitization, e.g., treatment of the silver halide with a strong reducing agent which introduces small specks of metallic silver into the silver salt crystal or grain.

In another embodiment, the silver halide emulsions can comprise silver halide grains having centers which promote the deposition of photolytic silver which are either sufficiently small or sufficiently buried within the crystal as to be not aceessible to initiate development to a visible image. Silver halide grains of this type can be provided by either using very low concentrations of the sensitizing agent throughout the precipitation or adding the sensitizing agent to the precipitation medium during the initial part of the precipitation..

whereby the concentration of the sensitizing agent will be lowered significantly by occlusion of the agent in the grains so that continued precipitation would result in lowered concentration of centers for promoting deposition of photolytic silver in the outer regions of each grain.

The practice of this invention is particularly suitable for high-speed, direct-positive emulsions comprising fogged silver halide grains and a compound which accepts electrons, as described and claimed in lllingsworth, US. Pat. No. 3,501.307 issued Mar. 17, 1970. The fogged silver halide grains of such emulsions are such that a test portion thereof, when coated as a photographic silver halide emulsion on a support to give a maximum density of at least about 1 upon processing for 6 minutes at about 68 F. in Developer A, has a maximum density which is at least about 30 percent greater than the maximum density of an identical coated test portion which is processed for 6 minutes at about 68 F. in the same developer afterbeing bleached for about 5 at about 68 F. in a 0.3 percent aqueous potassium ferricyanide solution.

The silver halides employed in the preparation of the photographic emulsions useful in this invention include any of the photographic silver halides which contain at least 50 mole percent chloride, as exemplified by silver chloride, silver chlorobromide, silver chlorobromoiodide, and the like. Emulsion blends, e.g., blends of silver chloride and a silver chlorobromide, can be used. Also, the core of the silver halide grain can be composed of silver halide of different composition than that in the outer shell of the grain. In any case, the total chloride present as'silver chloride or silver chlorohalide should be at least 50 mole percent of the total halide in the emulsion.

Silver halide grains having an average grain size less than about 1 micron, preferably less than about 0.75 micron, give particularly good results. The silver halide grains can be regular and can be any suitable shape such as cubic or octahedral, as described and claimed in lllingsworth, U.S. Pat. No. 3,501,306 issued Mar. 17, 1970, entitled Regular Grain Photographic Reversal Emulsions." Such grains advantageously have a rather uniform diameter frequency distribution, as described and claimed in lllingsworth, U.S. Pat. No. 3,501,305 issued Mar. 17, 1970, entitled Monodispersed Photographic Reversal Emulsions. For example, at least 95 percent, by weight, of the photographic silver halide grains can, have a diameter which is within about 40 percent, preferably within about 30 percent, of the mean grain diameter. Mean grain diameter, i.e., average grain size, can be determined using conventional methods, e.g., as shown in an article by Trivelli and Smith entitled Empirical Relations between Sensitometric and Size-Frequency Characteristics in Photographic Emulsion Series" in The Photographic Journal, Vol. LXXIX, 1949, pages 330-338. The fogged silver halide grains in these direct-positive photographic emulsions of this invention produce a density of at least 0.5 when developed without exposure for 5 minutes at 68 F. in Developer A when such an emulsion is coated at a coverage of 50 to about 1,000 mg. of silver per square foot of support.

in preferred embodiments of this invention, electron acceptors and halogen conductors (sometimes referred to as halogen acceptors) are present in the direct-positive emulsions. When the grains of the silver halide emulsion are substantially free of internal sites for the deposition of photolytic silver, it is essential that an electron acceptor be present in the emulsion if it is to be reversed by blue light.

The electron acceptors or halogen conductors which give particularly good results in the practice of this invention can be characterized in terms of their polarographic halfwave potentials, i.e., their oxidation reduction potentials determined by polarography. The electron acceptors useful herein have an anodic polarographic potential and a cathodic polarographic potential, which, when added together, give a positive sum. The halogen conductors useful herein have an anodic polarographic potential less than 0.85 and a cathodic polarographic potential which is more negative than -l.0. Preferred halogen conductors have an anodic polarographic potential less than 0.62 and a cathodic polarographic potential which is more negative than i .3. Cathodic measurements can be made with a l X 1 0'4 molar solution of the electron acceptor in a solvent, for example, methanol which is 0.05 molar in lithium chloride using a dropping mercury electrode with the polarographic halfwave potential for the most positive cathodic wave being designated E, Anodic measurements can be made with I xl0'4 molar aqueous solvent solution. for example. methnnollc solutions of the electron acceptor which are 0.05 molar in sodium acetate and 0.005 molar in acetic acid using a carbon paste of pyrolytic graphite electrode, with the voltam' metric half peak potential for the most negative anodic response being designated E in each measurement, the reference electrode can be an aqueous silver --silver chloride (saturated potassium chloride) electrode at 20 C. Electrochemical measurements of this type are known in the art and are described in New instrumental Methods in Electrochemistry, by Delahay, Interscience Publishers, New York, 1954; Polarography, by Kolthoff and Lingane, 2nd Edition, Inter-science Publishers, New York, New York, 1952; Analytical Chemistry, 36, 2426 i964) by Elving; and Analytical Chemistry, 30, 1576 (1958) by Adams. Signs are given according to lUPAC, Stockholm Convention 1953.

Advantageously, these electron acceptors used herein also provide spectral sensitization such that the ratio of minus blue relative speed to blue relative speed of the emulsion is greater than.7, and preferably greater than 10, when exposed to a tungsten light source through Wratten No. 16 and No. 35 plus 38A filters respectively; Such electron acceptors can be termed spectrally sensitizing electron acceptors." However, electron acceptors can be used which do not spectrally sensitize the emulsion.

An especially useful class of electron acceptors which can be used in the direct-positive photographic silver halide emulsions and processes of this invention are cyanine dyes, such as the imidazo[4,5-b] quinoxaline dyes. Dyes of this class are described in Brooker and Van Lare Belgian Pat. 660.253 issued Mar. 15, i965. In these dyes, the imidazo[4,5-b] quinoxaline nucleus is attached, through the 2-carbon atom thereof, to the methine chain. Typical good electron acceptor dyes used in direct-positive emulsions are disclosed in lllingsworth and Spencer, Belgian Pat. 695,364 granted Sept. 1 1, i967.

A preferred class of halogen-conducting compounds useful in this invention is characterized by an anodic half wave potential which is less than 0.62 and a cathodic half wave potential which is more negative than l.3. A preferred class of halogen conductors that can be used in the practice of this invention comprises the spectral sensitizing merocyanine dyes having the formula:

where A represents the atoms necessary to complete an acid heterocyclic nucleus, e.g., rhodanine, Z-thiohydantoin and the like, B represents the atoms necessary to complete a basic nitrogen-containing heterocyclic nucleus, e.g., benzothiazole, naphthothiazole, benzoxazole and the like, each L represents a methine linkage, e.g.,

and n is an integer from 0 to 2, i.e., O, l or 2. Typical halogenconducting compounds are disclosed in Wise, Belgian Pat. 695,361 granted Sept. ll, 1967.

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

One of the most convenient ways to develop exposed highcontrast elements of this invention is to process them in a continuous transport processing machine. Such machines are disclosed, for example, in U.S. lat. Nos. 3,025,779 of Russell and Kunz issued Mar. 20, 1962; 3,078,024 of Sardeson issued Feb. 19, 1963; 3,122,086 of Fitch issued Feb. 25, 1964; 3,149,551 of Cramer issued Sept. 22, 1964; 3,156,173 of Meyer issued Nov. 10, 1964; and 3,224,356 of Fleishcr and l-lixon issued Feb. 21, 1965. In such machines, the element is processed in one continuous motion by transporting it into and out of at least one processing solution. The roller transport processing machine of the type disclosed in the Russell and Kunz patent mentioned above has been found to be especially useful.

The photographic. elements of this invention can also contain certain onium salts, such as quaternary ammonium salts, sulfonium salts and phosphonium salts in order to increasethe development rate without adversely affecting the improved dot quality and contrast. Such compounds are disclosed, for example, in Carroll U.S. Pat. No. 2,271,623 issued Feb. 3, 1942; Beavers et a1. U.S. Pat. Nos. 2,944,898 issued July 12, 1960; Carroll et a1. U.S. Pat. Nos. 2,944,900 issued July 12, 1960, 2,288,226 issued June 30, 1942, 2,275,727 issued Mar. 10, 1942, and 2,271,622 issued Feb. 3, 1942; Agfa British Pat. No. 1,067,958 published May 10, 1967; and Piper U.S. Pat. No. 2,886,437 issued May 12, 1959. Concentrations ranging from about 0.01 to about 2.0 grams of onium salt per mole of silver in the silver halide emulsion can be used with good results.

The silver halide emulsion of a photographic element useful in this invention can contain conventional addenda' such as gelatin plasticizers, coating aids, antifoggants such as the azaindines and hardeners such as aldehyde hardeners, e.g., formaldehyde, mucochloric acid,'glutaraldehyde bis(sodium bisulfite), maleic dialdehyde, aziridines, dioxane derivatives and oxypolysaccharides.

The addition of from about 0.005 to about 2.0 grams of a 3- pyrazolidone per mole of silver in the emulsion will also increase the development rate. The pyrazolidones used to advantage include those disclosed in U.S. Pat. No. 2,751,297 of Hood and Crookshank issued June 19, 1956, and represented by the following general formula:

wherein X represents hydrogen or acetyl, R represents a heterocyclic group or an aryl group of the benzene or naphthalene series and R 1 represents hydrogen, an alkyl group or an aryl group of the benzene or naphthalene series, and R and R each represents hydrogen or an alkyl group. Examples within this formula include l-phenyl-3-pyrazolidone; 5- methyl-3-pyrazolidone; 1-phenyl-5-phenyl-3-pyrazolidone; 1- phenyl-5-methyl-3-pyrazolidone; l-phenyl-4,4-dimethyl-3- pyrazolidone; l-p-hydroxyphenyl-4,4-dimethyl-3- pyrazolidone; 4-methyl-l-phenyl-3-pyrazolidone; etc. The above 3-pyrazolidones can also be contained in a contiguous layer instead of the silver halide emulsion if desired.

in the preparation of the above photographic emulsions, the electron acceptors, halogen conductor, bromide and iodide salts are advantageously incorporated in the washed, finished silver halide emulsion and should, of course, be uniformly distributed throughout the emulsion. The methods of incorporating such addenda in emulsions are relatively simple and wellknown to those skilled in the art. For example, it is convenient to add them from solutions in appropriate solvents, in which case the solvent selected should be completely free from any deleterious elfect 0n the ultimate light-sensitive materials. Methanol, isopropanol, pyridine, water, etc., alone or in admixtures, have proven satisfactory as solvents for the electron acceptors and halogen acceptorm'The type of silver halide emulsions that can be sensitized with these dyes include any of those prepared with hydrophilic colloids that are known to be closed, for example, in U.S. Pat. Nos. 3,142,568, 3,193,386,

3,062,674 and 3,220,844, and include the water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The emulsions of the invention can also be used in combination with water-soluble. halide salts, e.g., bromide salts, as described in Litzerman Belgian Patent 695,363 granted Sept. 11, 1967. Y

The invention can be further illustrated by the following examples.

EXAMPLE 1 A silver chloride emulsion is prepared by simultaneously adding over a period of 20 minutes at 70 C. one-half mole of silver nitrate and one-half mole of sodium chloride to a solution containing 10 grams of gelatin. The emulsion formed is cooled to 40 C., 50 milligrams of potassium chloroiridite are added and the emulsion is held for 10 minutes. The temperature is then raised to 70 C. This emulsion constitutes the silver chloride core containing discontinuities which trap electrons.

The shell of silver chloride is formed by adding another onehalf mole each of silver nitrate and sodium chloride over a period of about-20 minutes. The emulsion is cooled to 40 C., an additional 70 grams of gelatin are added and the whole is chill-set and washed with cold water for 2 hours. The washed emulsion is chemically sensitized into fog by heating to about 65 C. for 30 minutes with 2 milligrams of thiourea dioxide per silver mole until high contrast is obtained and the emulsion develops to maximum density without being exposed.

The emulsion is spectrally sensitized with 3-carboxymethyl- 5- [3-methyl-2(3)-thiazolinylidene] isopropylidene rhodanine [DYE I] (also serves as a halogen-conducting compound) and then a portion of it is coated upon a cellulose triacetate film support with sufficient added gelatin to give coverages of 250 milligrams of silver and 370 milligrams of gelatin per square foot. To the other portion of the emulsion is added 25 milligrams of Pluronic L-44 (a water-soluble block copolymer of ethylene oxide and propylene oxide) per mole of silver in the silver halide emulsion and then coated upon a cellulose triacetate film support with sufficient added gelatin to give coverages of 250 milligrams of silver and 370 milligrams of gelatin per square foot.

Samples of the coated elements are then exposed on an intensity scale sensitometer and one sample developed for 1% minutes in Kodak Developer D and the other developed for -l minute in Kodak Developer D-l l. The formulas for these developers are as'follows:

The following results are obtained:

D-85 developer D-11 developer Rel. Rel. Coated element speed 7 Din. Dmin. peed Y Durex. m n.

Without polymer 100 12. 2 3. 6 06 100 12. 9 Q 2. 6 21 With polymer 115 16 2. 28 06 100 16. 2. 29 22 The above results show that the addition of an alkylene oxide polymer to the particular high-contrast, direct-positive photographic elements described herein when processed in a developer wherein the developing agent consists essentially of a polyhydroxybenzene compound increases speed and/or increases y.

EXAMPLE 2 A silver chlorobromide emulsion is prepared by simultaneously adding over a period of minutes, 0. 5 mole of silver nitrate, 0.025 mole of potassium bromide and 0.225 mole of sodium chloride to a solution containing grams of gelatin at 65 C. Twenty milligrams of potassium chloroiridite are added and the emulsion is held for 10 minutes. This emulsion constitutes the silver chlorobromide core containing discontinuities which trap electrons.

The shell of silver chlorobromide is formed by adding an additional 0.75 mole of silver nitrate, 0.075 mole of potassium bromide and 0.675 mole of sodium chloride over a period of about minutes at 65 C. An additional 40 grams of gelatin are added, the emulsion is cooled and sufficient saturated sodium sulfate solution is added to coagulate the emulsion. The separated and washed coagulum is dispersed in water with an additional grams of gelatin and is set, washed and chemically sensitized as in example 1.

The emulsion is then spectrally sensitized as in example 1 and then coated in the same manner with and without Pluronic L-44 polymer, except at a silver coverage of 477 milligrams per square foot and a gelatin coverage of 466 milligrams per square foot. A gelatin layer is coated at 83 milligrams of gelatin per square foot over the emulsion layer.

Samples of coated elements are then exposed as in example 1 and one sample developed for 3% minutes in Kodak Developer D-85 and the other developed for 2 minutes in Kodak Developer O-l l. The following results are obtained:

The above results illustrate that very large speed increases can be obtained by employing the particular halogen-conducting compounds as defined herein. This speed increase is a very important factor in providing a camera-speed, direct-positive, high-contrast photographic element.

EXAMPLE 4 A silver chlorobromide emulsion is prepared by adding simultaneously 0.9 mole of sodium chloride, 0.1 mole of potassium bromide and 1 mole of silver nitrate over a period of 36 minutes at 70 C. to a solution containing 10 grams of gelatin and 40 milligrams of potassium chloroiridite. An additional 40 grams of gelatin are added and the emulsion is cooled to 40 C. One hundred grams of a 10 percent gelatin solution are then added and the emulsion is chill-set and washed with cold water. The washed emulsion is then chemi cally fogged by heating with thiourea dioxide (0.3 milligram per silver mole, 20 minutes at 65 C.), adding potassium chloroaurate (0.2 milligram per silver mole, minutes at 65 C.) and continuing heating until high contrast is obtained and the emulsion develops to maximum density without being exposed.

The emulsion is then spectrally sensitized as in example 1 and then coated in the same manner with and without 125 milligrams of polyethylene glycol oleyl ether per mole of silver in the silver halide emulsion, except at a silver coverage of 340 milligrams per square foot and a gelatin coverage of 337 milligrams per square foot. A gelatin layer is coated at 83 milligrams of gelatin per square foot over the emulsion layer.

Samples of the coated elements are then exposed as in example 1 and one sample developed for 2% minutes in Kodak D-85 Developer, another sample developed for 2 minutes in Kodak D-ll Developer and a third sample developed for 1% in the following amine-type of developer disclosed and D-85 developer D-ll developer The same improvements noted in example 1 are shown by this example also.

claimed in application Ser. No. 583,935 filed Oct. 3, 1966, now abandoned of my coworker Masseth:

EXAMPLE 3 Sodium-bis-(2-hydroxyethyl)ammu- A portion of the emulsion of example 2 (before spectral 5 i j' 25-3 sensitization) is spectrally sensitized with 0.5 gram per silver z 'r'z is mole of a sulfobutyl-pyridyl-rhodanine dye of the type Hydmqmmne 225 yams described in U.S. Pat. No. 2,519,001 of Sprague issued Aug. Potassium bromide [,6 grams 15, 1950. This dye also serves as a halogen-conducting coma i fi pound as defined herein. The emulsion is then coated as in exma 8 ample 2. Another portion of this same emulsion is coated as in xam 1e 2 withouta halo en-conductin com ounde p g g p The following results are obtained:

Samples of the coated elements are then exposed as in example 1 and developed for 1% minutes in Kodak Developer D-85 with the following results:

D-ll D-85 Amine-type Developer Developer Developer Coated Rel. Rel. Rel. Coated Element Relative Speed -y Element Speed 7 Speed 7 Speed 7 Without halogen-conducting Without compound 100 3.8 polymer 89 5 X 100 5.2 76 9.0 With halogen-conducting With compound 4,170 4.5 polymer 94 5.9 2 I14 I07 12.0

The above results show significant increases both in relative speed and -y when alkylene oxide polymers are added to the particular high-contrast, direct-positive photographic elements described herein when processed in developers wherein the developing agent consists essentially of a polyhydroxybenzene compound.

EXAMPLE 5 chloroaurate (1.72 milligrams) are added and the emulsion is 15 held for 10 minutes. This emulsion constitutes the silver chlorobromide core containing discontinuities which trap electrons.

The shell of silver chlorobromide is formed by adding an additional 0.75 mole of silver nitrate, 0.675 mole of sodium chloride and 0.075 mole of potassium bromide over a period of about 15 minutes at 65 C. An additional 40 grams of gelatin are added and the emulsion is chill-set, washed and fogged by heating with 0.75 milligrams of thiourea dioxide for 40 minutes at 65 C. 2 5

The emulsion is then spectrally sensitized as in example 1 and then coated in the same manner with and without 125 milligrams of polyethylene glycol oleyl ether per mole of silver in the silver halide emulsion, except at a silver coverage of 477 milligrams per square foot and a gelatin coverage of 466 milligrams per square foot. A gelatin layer is coated at 83 milligrams of gelatin per square foot over the emulsion layer.

Samples of the coated elements are exposed as in Example 1 and a second set exposed through a magenta contact halftone screen and both sets developed for 2% minutes in Kodak D-85 Developer with the following results:

Sensitometric Halftone Screen Exposure Exposure Coated Element Relative Speed 7 Dot Quality Without polymer 100 l 1 I With polymer 110 16+ 9 determined by examining the dot areas and assigning a number ranging from 9 (Excellent) to 1 (Extremely poor) The above results show significant increases in relative speed, 7 and dot quality when alkylene oxide polymers are added to the particular high-contrast, direct-positive photographic elements described herein.

EXAMPLE 6 The emulsion of example 4 without an alkylene oxide polymer is coated upon a polyethylene terephthalate film support at a silver coverage of 380 milligrams per square foot. Another portion of the emulsion is coated in a similar manner upon a gelatin layer containing 100 milligrams of gelatin per Sensitomctric Halftonc Screen Exposure Exposure Coated Element Relative Speed -y Dot Quality Without polymer 100 4.4 I With polymer in adjacent layer 1 15 8.4 7

The above results show that increases in relative speed, 7 and dot quality may be obtained according to the invention when the alkylene oxide polymer is contained in a contiguous layer.

EXAMPLE 7 Samples of the control elements of example 4 and example 6 (without an alkylene oxide polymer) are exposed on an intensity scale sensitometer and processed for 2 /4 minutes in Kodak D- Developer, with and without 1 gram of the oleyl ether of polyethylene glycol (molecular weight of about 1,500) per liter of developer, fixed, washed and dried with the following results:

Developer without Developer with polymer polymer Rel. Con- Rel. Conspeed trol Dlnllspeed trol Du",l

Example 4 (control) 4. 75 2. 85 141 15. T 3. 15 Example 6 (control)- 4. 70 3. 35 162 11. B 3. 50

It can be seen from the above results that the addition of an alkylene oxide polymer to the developer increases speed, contrast and D of the elements processed therein.

EXAMPLE 8 A silver chlorobromoiodide emulsion is prepared by simultaneously adding over a period of 35 minutes at 55 C. 0.4875 mole of potassium bromide, 0.0125 mole of potassium iodide and 0.50 mole of silver nitrate to a solution containing 21 grams of gelatin. An additional 19 grams of gelatin are added and the emulsion is chill-set and washed with cold water. An additional 61.5 grams of gelatin are added, the emulsion is melted at 60 C. and 4.5 moles of sodium chloride and 4.5 moles of silver nitrate are simultaneously added over a period of 24 minutes at 60 C. An additional 50 grams of gelatin are added and the emulsion is chill-set, washed and chemically fogged as in example 4.

The emulsion is then spectrally sensitized as in example 1. To one sample of the emulsion is added milligrams of polyethylene glycol oleyl ether per mole of silver in the silver halide emulsion and to another sample is added the same amount of polymer plus 15 milligrams of l-phenyl-4-methyl-3- pyrazolidone per mole of silver in the silver halide emulsion.

The various samples are then coated as in example example 1 except at a silver coverage of 477 milligrams per square foot and a gelatin coverage of 466 milligrams per square foot. Samples of the coated elements are then exposed as in example 1 and a second set exposed as in example 5. One set of samples with a sensitometric exposure is developed for 3% minutes and another set developed for 3% minutes in Kodak D-85 Developer, while the second set with the halftone screen exposure is developed for 2 minutes in the amine-type" developer described in example 4. The following results are obtained:

Kodak D-85 developer 3% minutes 3% minutes Amine-type" developer Rel. Rel. Rel. not Coated element speed 7 1),... speed 7 Din. Speed 1 Um quality Without polymer. 100 11 4. 69 97 11 4. 65 100 4. (i 4. 1| 1 W th polymer. 13. 2 4. 2 123 16+ 4. 66 470 7. 0 4. 3 (H/ With polymer and 3-pyrazolidone. .11 16+ 4. 60 257 10. 5 5.0 7

The above results indicate that the addition of the 3- pyrazolidone to the coated element permits development to D in a shorter time with no loss in dot quality or contrast (compare 3%, minutes with 3% minutes in Kodak D-85 Developer). Using the amine-type of developer, the addition of the 3-pyrazolidone to the coated element provides increases in y, D and dot quality.

EXAMPLE 9 A silver chlorobromide emulsion which is substantially free of internal centers for the deposition of photolytic silver is prepared by adding simultaneously 0.9 mole of sodium chloride, 0.1 mole of potassium bromide and 1 mole of silver nitrate over 50 minutes at 50 C. to a solution of 43 g. of gelatin. An additional 37 g. of gelatin is added and the emulsion is chill-set and washed. The washed emulsion is chemically fogged by heating with thiourea dioxide (0.3 mg./Ag mole for 20 minutes at 65 C. adding potassium chloroaurate (0.2 mg./Ag mole for 50 minutes at 65 C.) and continued heating until high contrast is obtained and the emulsion develops to maximum density without being exposed. Before coating, mg. of l-phenyl-4-methyl-3-pyrazolidone/mole and 400 mg. of a phenyl-imidazo-quinoxaline-indolo carbocyanine dye (US. application, Ser. No. 609,791, now US. Pat. No. 3,431,111 Brooker and VanLare) is added to the emulsion. To a portion of this emulsion is added 125 mg. of polyethylene glycol oleyl ether-molecular weight of about 1,540. Both emulsions are coated on a polyester (polyethylene terephthalate) film support. The coatings are exposed, developed 2% minutes in Kodak D-85 Developer, fixed, washed and dried with the following results:

2% Kodak D-85 Developer An emulsion is prepared according to the procedures of example 9. Portions of the emulsion are spectrally sensitized with Dye I at 400 mg./Ag mole plus a phenyl-imidazo-quinoxalineindolo carboncyanine dye (Dye III) at 75 mg./Ag mole and Dye l (400) plus a pyrazolyl-vinyl-imidazo-quinoxaline carbocyanine dye at 300 mg./Ag mole (Dye IV). To portions of the emulsion are added development restrainers with and without l-phenyl-4-methyl-3-pyrazolidone (MP) as listed in the table below. The emulsions are coated without bromide addition. The films are exposed and processed to direct-positive images.

The following results show the advantages of adding a development restrainer to a fogged direct-positive emulsion containing a halogen-conducting dye plus an electron-accepting dye; these advantages are increased speed, very high contrast and excellent dot quality.

Feature 3% Kodak D-85 Table-Continued Dyel+DyelV 100 5.8 Dye I Dye IV PEG(l87.5)+MP(l5) 74 10.8

3% Kodak D- Rel. DotOuality Speed 7 H M S Dyel+DyelV I00 5.3 l.() l.0 l Dye Dye IV Pluronic L-44 (35) MP (l5) 229 l6.+ 8.5 8.5 9

H highlight dots; M middle tone (50 percent) dots; S shadow dots Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and in the appended claims.

I claim:

1. In a direct-positive, high contrast photographic element comprising a support and a direct-positive-blue-sensitive fogged silver halide composition wherein the halide of said silver halide is at least 50 mole percent chloride, the improvement comprising at least one layer in said element containing a water-soluble alkylene oxide polymer having a molecular weight of at least 300.

2. A direct-positive element according to claim 1 wherein said silver halide composition comprises a spectral-sensitizing dye.

3. A direct-positive element according to claim 1 wherein said silver halide composition comprises chemically fogged silver halide grains.

4. A photographic element according to claim 10 wherein said alkylene oxide polymer is present in said element in an amount of less than about 10 grams per mole of silver in said silver halide composition.

5. The photographic element of claim I wherein said alkylene oxide polymer is present in a layer contiguous to said silver halide composition.

6. The photographic element of claim 1 wherein said alkylene oxide polymer is present in said silver halide composition.

7. The photographic element according to claim 1 wherein said silver halide comprises silver halide grains having internal centers which promote the deposition of photolytic silver and an outer region ofa fogged silver halide.

8. The photographic element of claim 1 wherein said silver halide grains have a halogen-conducting compound contiguous therewith, wherein said halogen-conducting compound has an anodic half wave potential which is less than 0.85 and a cathodic half wave potential which is more negative than -l .0.

9. The photographic element of claim 7 wherein said centers in said silver halide grains which promote the deposition of photolytic silver are obtained from an iridium salt.

10. The photographic element of claim 1 wherein said alkylene oxide polymer is an ethylene oxide polymer in which the ethylene oxide moiety has an average molecular weight of from about 300 to about 4,000.

11. The photographic element of claim 1 wherein said halide is at least about 70 mole percent chloride.

12. The photographic element of claim 8 wherein said halogen-conducting compound is a merocyanine dye.

13. The photographic element of claim 1 which also con tains a 3-pyrazolidone.

14. The photographic element of claim 13 wherein said 3- pyrazolidone is l-phenyl-4-methyl-3-pyrazolidone.

15. The photographic element according to claim 1 wherein said silver halide comprises fogged silver halide grains and an organic compound which accepts electrons which has an anodic half wave potential and a cathodic half wave potential which, when added together. give a positive sum, said grains being such that a test portion thereof, when coated as a photographic silver halide emulsion on a support to give a maximum density of at least about 1 upon processing for 6 minutes at about 68 F. in Developer A, has a maximum density which is at least about 30 percent greater than the maximum density of an identical coated test portion which is processed for 6 minutes at about 68 F. in the same developer after being bleached for about minutes at about 68 F. in a 0.3 percent aqueous potassium ferricyanide solution wherein Developer A has the formula:

N-methyl-p-aminophenol sulfate 16. A photographic element according to claim 1 wherein said silver halide composition comprises an electron-accepting compound and a halogen-conducting compound, wherein said halogen-conducting compound has an anodic half wave potential which is less than 0.85 and a cathodic half wave potential which is more negative than 1 .0.

17. A photographic element according to claim 1 further comprising a water-soluble halide and an onium salt.

18. The photographic element according to claim 16 wherein the electron acceptor is a cyanine dye.

19. The photographic element according to claim wherein said silver halide grains are reduction and gold fogged.

20. A process comprising developing in the presence of a water-soluble alkylene oxide polymer, which has a molecular weight of at least 300, an exposed, direct-positive, high-contrast photographic element in a photographic developer comprising a silver halide developing agent consisting essentially of a polyhydroxybenzene compound, said photographic element comprising a support coated with a directpositive-bluesensitive, chemically fogged silver halide emulsion, wherein the halide of said silver halide is at least 50 mole percent chloride.

21. The process of claim 20 wherein said alkylene oxide polymer is present in said element in an amount of less than about 1 gram per mole of silver in said silver halide emulsion.

22. The process of claim 20 wherein said alkylene oxide polymer is present in said silver halide emulsion.

23. The process of claim 20 wherein said alkylene oxide is present in the photographic developer.

24. The process of claim 20 wherein said polyhydroxybenzene compound is hydroquinone.

25. The process of claim 20 wherein said developer also contains a carbonyl bisulfite-amine condensation product.

26. The process of claim 20 wherein said developer contains at least about 0.075 mole per liter offree amine.

27. The process of claim 20 wherein said alkylene oxide polymer is an ethylene oxide polymer in which the ethylene oxide moiety has an average molecular weight of from about 300 to about 4,000.

28. The process of claim 20 wherein said halide is at least about 70 mole percent chloride.

29. The process of claim 20 wherein the silver halide of said photographic element comprises silver halide grains having internal centers which promote the deposition of photolytic silver and an outer region for said core of a fogged silver halide.

30. The process of claim 20 wherein said silver halide grains have a halogen-conducting compound contiguous therewith, wherein said halogen-conducting compound has an anodic half wave potential which is less than 0.85 and a cathodic half wave potential which is more negative than --1 .0.

31. The process of claim 30 wherein said silver halide grains have an electron-conducting compound contiguous therewith, said electron-conducting compound having an anodic half wave potential and a cathodic half wave potential which, when added together, give a positive sum.

32. The process of claim 29 wherein said centers in said silver halide grains which promote the deposition of photolytic silver are obtained from an iridium salt.

33. The process of claim 20 wherein the silver halide of said photographic element comprises fogged silver halide grains and an organic compound which accepts electrons which has an anodic half wave potential and a cathodic half wave potential which, when added together, give a positive sum, said grains being such that a test portion thereof, when coated as a photographic silver halide emulsion on a support to give a maximum density of at least about 1 upon processing for 6 minutes at about 68 F. in Developer A, has a maximum density which is at least about 30 percent greater than the maximum density of an identical coated test portion which is processed for 6 minutes at about 68 F. in the same developer after being bleached for about 5 minutes at about 68 F. in a 0.3 percent aqueous potassium ferricyanide solution wherein Developer A has the composition:

N-methyl-p-aminophcnol sulfate 2.5 g. sodium sulfite (anhydrous) 30.0 g. hydroquinone 2.5 g. sodium mctaborate 10.0 g. potassium bromide 0.5 g.

water to make 1.0 l.

34. The process of claim 33 wherein said electron acceptor is a cyanine dye.

323 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,615,519 Dated ctober 26, 1 971 Inventor(s) Kirby M. Milton It is certified that error appears in tI-e above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 70, "and" should read ---an-.

Column 2, llne 72, p should read ---pH---.

Column 3, line 8, "p should read ---pH--- Column 3, line 18, "raNge" should read --range---.

Column L line 1 9, "p and low p should read ---pH and low pAg--- Column 5, line 6, "about 5 at" should read ---about 5 minutes at---.

Column 5, line 67, "1X1 O'L should read ---IXI O Column 9, line LL}, "Kodak Developer O-ll should read ---Kodak Developer D-1 1---.

Column 13, line I "with 3-1/L minutes in Kodak 13-85" should read ---with 3-3/1; minutes in Kodak D-8S---.

Column 5, line 72, "1X1 O'LL" should read ---|X| O FIB-1050 UNITED STATES PATENT OFFICE 5 9 CERTIFICATE OF CORRECTION Patent No. T 51 9 Dated OCtObel 97 Inventor(s) Kirby M. Milton It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 2 Column l3, line 50, "carboncyanine dye" should read --carbocyanine dye---.

Column 1L line 35, "Claim 1 0" should read ---Claim 1---.

Column 114 line 3 7 "10 grams per mole" should read ---I gram per mole--- Signed and sealed this 5rd day of December 197 (SEAL) Attest:

C. MARSHALL DANN MCCOY M. GIBSON JR.

Commissioner of Patents Attesting Officer

Claims (33)

1. 2. A direct-positive element according to claim 1 wherein said silver halide composition comprises a spectral-sensitizing dye.
2. 3. A direct-positive element according to claim 1 wherein said silver halide composition comprises chemically fogged silver halide grains.
3. 4. A photographic element according to claim 1 wherein said alkylene oxide polymer is present in said element in an amount of less than about 1 gram per mole of silver in said silver halide composition.
4. 5. The photographic element of claim 1 wherein said alkylene oxide polymer is present in a layer contiguous to said silver halide composition.
5. 6. The photographic element of claim 1 wherein said alkylene oxide polymer is present in said silver halide composition.
6. 7. The photographic element according to claim 1 wherein said silver halide comprises silver halide grains having internal centers which promote the deposition of photolytic silver and an outer region of a fogged silver halide.
7. 8. The photographic element of claim 1 wherein said silver halide grains have a halogen-conducting compound contiguous therewith, wherein said halogen-conducting compound has an anodic half wave potential which is less than 0.85 and a cathodic half wave potential which is more negative than -1.0.
8. 9. The photographic element of claim 7 wherein said centers in said silver halide grains which promote the deposition of photolytic silver are obtained from an iridium salt.
9. 10. The photographic element of claim 1 wherein said alkylene oxide polymer is an ethylene oxide polymer in which the ethylene oxide moiety has an average molecular weight of from about 300 to about 4,000.
10. 11. The photographic element of claim 1 wherein said halide is at least about 70 mole percent chloride.
11. 12. The photographic element of claim 8 wherein said halogen-conducting compound is a merocyanine dye.
12. 13. The photographic element of claim 1 which also contains a 3-pyrazolidone.
13. 14. The photographic element of claim 13 wherein said 3-pyrazolidone is 1-phenyl-4-methyl-3-pyrazolidone.
14. 15. The photographic element according to claim 1 wherein said silver halide comprises fogged silver halide grains and an organic compound which accepts electrons which has an anodic half wave potential and a cathodic half wave potential which, when added together, give a positive sum, said grains being such that a test portion thereof, when coated as a photographic silver halide emulsion on a support to give a maximum density of at least about 1 upon processing for 6 minutes at about 68* F. in Developer A, has a maximum density which is at least about 30 percent greater than the maximum density of an identical coated test portion which is processed for 6 miNutes at about 68* F. in the same developer after being bleached for about 5 minutes at about 68* F. in a 0.3 percent aqueous potassium ferricyanide solution wherein Developer A has the formula: N-methyl-p-aminophenol sulfate 2.5 g. sodium sulfite (anhydrous) 30.0 g. hydroquinone 2.5 g. sodium metaborate 10.0 g. potassium bromide 0.5 g. water to make 1.0 l.
15. 16. A photographic element according to claim 1 wherein said silver halide composition comprises an electron-accepting compound and a halogen-conducting compound, wherein said halogen-conducting compound has an anodic half wave potential which is less than 0.85 and a cathodic half wave potential which is more negative than -1.0.
16. 17. A photographic element according to claim 1 further comprising a water-soluble halide and an onium salt.
17. 18. The photographic element according to claim 16 wherein the electron acceptor is a cyanine dye.
18. 19. The photographic element according to claim 15 wherein said silver halide grains are reduction and gold fogged.
19. 20. A process comprising developing in the presence of a water-soluble alkylene oxide polymer, which has a molecular weight of at least 300, an exposed, direct-positive, high-contrast photographic element in a photographic developer comprising a silver halide developing agent consisting essentially of a polyhydroxybenzene compound, said photographic element comprising a support coated with a direct-positive-blue-sensitive, chemically fogged silver halide emulsion, wherein the halide of said silver halide is at least 50 mole percent chloride.
20. 21. The process of claim 20 wherein said alkylene oxide polymer is present in said element in an amount of less than about 1 gram per mole of silver in said silver halide emulsion.
21. 22. The process of claim 20 wherein said alkylene oxide polymer is present in said silver halide emulsion.
22. 23. The process of claim 20 wherein said alkylene oxide is present in the photographic developer.
23. 24. The process of claim 20 wherein said polyhydroxybenzene compound is hydroquinone.
24. 25. The process of claim 20 wherein said developer also contains a carbonyl bisulfite-amine condensation product.
25. 26. The process of claim 20 wherein said developer contains at least about 0.075 mole per liter of free amine.
26. 27. The process of claim 20 wherein said alkylene oxide polymer is an ethylene oxide polymer in which the ethylene oxide moiety has an average molecular weight of from about 300 to about 4,000.
27. 28. The process of claim 20 wherein said halide is at least about 70 mole percent chloride.
28. 29. The process of claim 20 wherein the silver halide of said photographic element comprises silver halide grains having internal centers which promote the deposition of photolytic silver and an outer region for said core of a fogged silver halide.
29. 30. The process of claim 20 wherein said silver halide grains have a halogen-conducting compound contiguous therewith, wherein said halogen-conducting compound has an anodic half wave potential which is less than 0.85 and a cathodic half wave potential which is more negative than -1.0.
30. 31. The process of claim 30 wherein said silver halide grains have an electron-conducting compound contiguous therewith, said electron-conducting compound having an anodic half wave potential and a cathodic half wave potential which, when added together, give a positive sum.
31. 32. The process of claim 29 wherein said centers in said silver halide grains which promote the deposition of photolytic silver are obtained from an iridium salt.
32. 33. The process of claim 20 wherein the silver halide of said photographic element comprises fogged silver halide grains and an organic compound which accepts electrons which has an anodic half wave potential and a cathodic half wave potential which, when added together, give a positive sum, said grains being such that a test portion thereof, when coated as a photographic silver halide emulsion on a support to give a maximum density of at least about 1 upon processing for 6 minutes at about 68* F. in Developer A, has a maximum density which is at least about 30 percent greater than the maximum density of an identical coated test portion which is processed for 6 minutes at about 68* F. in the same developer after being bleached for about 5 minutes at about 68* F. in a 0.3 percent aqueous potassium ferricyanide solution wherein Developer A has the composition: N-methyl-p-aminophenol sulfate 2.5 g. sodium sulfite (anhydrous) 30.0 g. hydroquinone 2.5 g. sodium metaborate 10.0 g. potassium bromide 0.5 g. water to make 1.0 l.
33. 34. The process of claim 33 wherein said electron acceptor is a cyanine dye.