US3418122A

US3418122A - Photodevelopment of silver halide print-out material

Info

Publication number: US3418122A
Application number: US481918A
Authority: US
Inventors: Ralph S Colt
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1965-08-23
Filing date: 1965-08-23
Publication date: 1968-12-24
Anticipated expiration: 1985-12-24
Also published as: DE1547726A1; BE685580A; DE1547726C3; DE1547726B2; GB1158635A

Description

United States Patent 3,418,122 PHOTODEVELOPMENT 0F SILVER HALIDE PRINT-OUT MATERIAL Ralph S. Colt, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Aug. 23, 1965, Ser. No. 481,918 17 Claims. (Cl. 96--63) ABSTRACT OF THE DISCLOSURE Process for providing a direct-print material which is chemically developable to a visible image comprising imagewise exposing a fine-grain silver halide photographic print-out material comprising silver halide grains which have trivalent metal ions occluded therein, repressing the print-out ability of the silver halide by heating to at least 300 F. and exposing said silver halide to light to produce a visible image.

This invention relates to the preparation of photodeveloped images on silver halide sensitized photographic materials and particularly to a method of producing such images on normally nonphotodevelopable print-out materials.

It is well known that photographic prints of good density and contrast can be produced on silver-sensitized coatings, without chemical treatment, by the so-called print-out process which involves the imagewise photolysis of silver salts. In this process, the coating is exposed sufiiciently to print out a visible silver image. Historically, such print-out silver images were the first to be produced in the development of the silver halide photographic process. However, relatively prolonged exposures are required for producing print-out images, and moreover, such images are quite unstable. The images are not fixed and background density prints out when exposed to roomlight.

The relative simplicity of the print-out process, which requires no wet processing and obviates drying, has stimulated a search for new formulations and/ or photographic processing procedures which would retain the fundamental advantages while providing improved sensitivity, greater image stability, and more rapid access to the finished photograph.

A recent development has been the direct print process in which a much lower image exposure than that required for the conventional print-out process, is used to generate a latent image which is made visible by a subsequent uniform light exposure. High intensity light of short duration is used to make the image exposure, and light of lower intensity and longer duration is used for the second exposure which is termed the latent image intensifying (latensifying) or photodeveloping exposure. The efliciency of latensification or photodevelopment in the direct print process can be improved in a number of ways, particularly by lowering the intensity of the light employed. This unfortunately results in prolonged photodevelopment times. Such photodeveloped images, like print-out images, are not stable to prolonged exposure to further viewing light and the density difference between background and image decreases as further exposure occurs.

Photodevelopable direct print materials have already proved very useful in many image-recording applications. Still more widespread commercial application awaits development of faster procedures which will provide the photodeveloped image more rapidly.

It is accordingly an object of this invention to provide a new photodevelopment process which quickly provides silver images of high stability to light and of good contrast quickly from latent images exposed on normally nonphotodevelopable silver halide sensitized materials.

It is another object of this invention to provide a new rapid direct print process for use with silver salt sensitized photographic emulsion coatings to provide photodeveloped images of good density and contrast.

It is another object of this invention to provide a new direct print process that uses a non-optical physical treatment after latent image formation to permit photodevelopment of normally nonphotodevelopable latent images.

It is another object of this invention to provide a new direct print process that can be utilized to rapidly prepare visible images.

It is likewise an object of this invention to provide a new direct print process suitable for use with print-out silver halide systems.

It is a further object of this invention to provide a novel direct print photodevelopment process that will operate efiiciently over a wide range of intensities of image exposure.

It is a still further object of this invention to provide a novel direct print process that permits rapid photodevelopment by using light intensities much higher than the light intensities used for latent image formation.

These and other objects of the invention are attained by means of this invention as described more fully hereinafter.

In accordance with the invention a silver halide printout material is imagewise exposed to form a latent image, the exposed silver halide heated to at least about 300 F., and thereafter the heated silver halide is uniformly exposed to light for a sufficient time to produce a visible image. The silver halide print-out material utilized in the present process is the type that is capable of being exposed to light to form a latent image that is chemically developable to a visible image and which latent image is incapable of being photodeveloped by uniform exposure to a visible image of substantial discrimination (e.g., D -D =less than .1) at temperatures up to 250 F.

In accordance with the present process a print-out material that normally would uniformly fog if uniformly exposed to light after an imagewise exposure can be used to prepare light-stable visible silver images by heating to temperatures of at least about 300 F. prior to the photodevelopment or photolysis step. The heating step in the present process represses the usual printing out of unexposed or non-image areas (D the original recording sensitivity of the silver halide beinginactivated by such heating. The optimum temperature and time interval to which the silver halide print-out material is heated in accordance with the present process can be readily ascertamed by one of ordinary skill in the art by simply moditying such variables until an image having optimum or desirable discrimination density is obtained after photodevelopment. Temperatures of at least about 300 F. utilized and preferably at least about 350 F. The upper extremes of the heating conditions utilized in the present process can also be readily ascertained by one of ordinary skill in the art, such factors as the breaking down or charring of the support of the photographic element or the vehicle for the silver halide being practical considerations.

The initial imagewise exposure is to light in the spectrum range in which the silver halide is sensitive sufiicient to form a latent image (invisible image) in the silver halide material, but insutficient to cause the silver halide to print out. Such an image exposure can be effected with high or low intensity light. Such exposure conditions can be readily ascertained and vary widely with the type of silver halide material utilized. The latent image so formed is capable of being chemically developed to a visible silver image with known photographic developing compositions.

The final step in the present process is a uniform or over-all exposure of the image-exposed and heated silver halide material to light in the spectrum range in which the silver halide was initially sensitive (typically about 2500-5700 Angstrom units such as ordinary daylight, tungsten light, fiuoroescent light, etc.). This step is a photodevelopment or photolysis step and is utilized to develop the latent image formed in the initial imagewise exposure to a visible silver image of substantial discrimination. Such photodevelopment can be carried out during or after the heat treatment step. The development of the unexposed or non-image areas is repressed by the aforedescribed heating step.

A wide variety of silver halide systems that print out, but which cannot be photodeveloped after a latent image exposure to a visible image of substantial discrimination on uniform exposure to light when heated to temperatures up to 250 C., can be utilized. Light-developable directprint silver halide systems of the type typically exposed to a short duration, high-intensity light source to form a latent image and thereafter photodeveloped by exposure to a light source of longer duration and lower intensity than the imagewise exposure are not utilized in the present process. The present silver halide print-out systems are composed of fine-grain silver halide more typically having an average silver halide grain size of less than about .2 micron and generally ranging from about .01 to .2 micron.

A particularly useful photographic system that can be utilized in the process of the invention is a radiationsensitive silver halide print-out system containing unfogged silver halide grains formed in the presence of a trivalent metal ion in an acidic media, such silver halide system preferably having contiguous to the trivalent metalcontaining silver halide grains a halogen acceptor.

In preparing such photographic systems, trivalent metal ions are used in the precipitation or formation of the silver halide. Silver halide crystals are formed with trivalent ions on the inside of the crystals, i.e., silver halide crystals with trivalent ions occluded therein. Typical suitable trivalent metal ions include those of bismuth, iridium, rhodium and the like. Bismuth ions are particularly useful. The trivalent metal ion can be suitably added with the water-soluble silver salt (e.g., silver nitrate) or the water-soluble halide (e.g., sodium or potassium iodide, bromide or chloride) that are conventionally reacted to prepare or precipitate photographic silver halide. Likewise, the trivalent ions can be introduced into the silver halide precipitation vessel with a hydrophilic colloid such as gelatin. The trivalent metal ions can be added to the system as water-soluble inorganic salts, as organo-metallic materials, as complexes, or any other form of material that results in the availability of trivalent metal ions during the formation of silver halide. The amount of trivalent metal utilized can be widely varied, although at least about 1x10 and more generally 1 10- to 2, mole percent based on the silver halide is used.

In preparing the print-out silver halide with trivalent metal ions, the water-soluble silver salt and the watersoluble halide are reacted to precipitate the silver halide under acidic conditions. The pH of the silver halide precipitation is typically less than 6 and preferably less than 5. Such acids as phosphoric, trifluoracetic, hydrobromic, hydrochloric, sulfuric and nitric are typically utilized in the silver halide precipitating media to maintain acidic conditions.

Suitable silver halides used in preparing the photographic elements processed in accordance with the invention include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, and silver chlorobromiodide. The silver halide preferably contains at least 50% bromide, less than 10% iodide and less than 50% chloride on a molar basis. Both silver halide that forms latent images predominantly on the surface of the silver halide crystal or those that form latent images predominantly inside the silver halide crystal, such as those described in Davey and 4 Knott, US. Patent 2,592,250 issued Apr. 8, 1952, can be used in the materials of the present invention.

The silver halide used in preparing the photographic elements processed in accordance with the invention is typically utilized in an emulsion or dispersion containing a colloidal material. Gelatin is preferably used as the colloidal material, although other colloidal materials such as colloidal albumin, cellulose derivatives or synthetic resins, for instance, polyvinyl compounds can also be used. Mixtures of such dispersing agents in a wide range of proportions can be utilized,'typical of such mixtures being mixtures of gelatin and an acrylate-acrylic acid copolymer. Such emulsions can contain conventional addenda such as coating aids, plasticizers, sensitizing dyes, hardeners, etc.

'In addition to silver halide emulsions, vacuum deposited photographic silver halide substantially free of conventional vehicles, binders or dispersing agents can be processed in accordance with the invention. Such vacuum deposited silver halide can be utilized in accordance with the invention by incorporating the halogen acceptors in a coating or layer contiguous to the vacuum deposited light-sensitive material.

The silver halide utilized in the present instance is unfogged. Such silver halide contains no visible or developable latent image. The silver halide is sensitive to electromagnetic radiation such as light and x-ray.

A wide variety of halogen acceptors can be utilized in the silver halide systems processed in accordance with the invention. Such materials are well known to those skilled in the photographic art and are conventionally added to light-developable, direct print silver halide emul- SlOIlS.

Nitrogen-containing halogen acceptors are particularly useful in preparing the silver halide systems processed in accordance with the invention. Suitable nitrogen-containing halogen acceptors used can be represented -by the formulas,

wherein: -R, R and R can each be hydrogen atoms, alkyl radicals, aryl radicals, including substituted alkyl and aryl radicals, or acyl radicals (e.g.,

wherein R is a hydrogen atom, an alkyl radical or an aryl radical); \R can be a nitrogen-containing radical such as an amino radical or a thiocarbamyl radical, including substituted amino and thiocarbamyl radicals; and D represents the necessary atoms to complete a heterocyclic nucleus generally having 5 or 6 atoms including at least two nitrogen atoms and at least one divalent radical having the formula,

wherein X can be a sulfur atom, an oxygen atom, a selenium atom or an imino radical (-=NH). When a nitrogen atom comprising D or R is attached directly to the nitrogen atoms of the above formulas, at least one hyrogen atom is attached to at least one of such nitrogen atoms of the halogen acceptor. The amino radical for substituent R can be represented by the formula,

wherein R and R can each typically be such substituents as hydrogen atoms, alkyl radicals, aryl radicals or acyl radicals as described above for R and R The thiocarbamyl radical for substituent R can be represented by the formula,

wherein R and R can be the same substituents as R and R or amino radicals.

Particularly useful nitrogen-containing halogen acceptors used in the invention can be further represented by the following subgeneric formulas:

wherein: R R R R R R R R R and R can each be hydrogen atoms, al'kyl radicals, aryl radicals or acyl radicals as described above for R, R and R E can be a sulfur atom, an oxygen atom, a selenium atom or an imino radical; and Q and Z can be the necessary atoms to complete a heterocyclic nucleus generally having 5 or 6 members. Q and Z typically are the ,necessary atoms to complete such moieties as a triazole-thiol, a mercaptoimidazole, an imidazolidine-thione, a triazinethiol, a thiobarbituric acid, a thiouracil, a urazole including a thiourazole and the like heterocyclic moieties.

With respect to the above formulas of nitrogen-containing halogen acceptors: the aryl radical substituents are those of the naphthyl and phenyl series, and include such common substituents as alkyl groups, halogen atoms, acyl radicals and the like; the alkyl radical substituents typically can contain 1 to 20 carbon atoms and more generally 1 to 8 carbon atoms, and can be substituted with such radicals as aryl radicals, halogen atoms, acyl radicals and the like.

Typical halogen acceptors of the thiourea type represented by Formula A and Formula B are disclosed in copending Kitze application, now US. Patent No. 3,241,- 971 issued Mar. 22, 1966; and in copending Fix application, now US. Patent No. 3,326,689. Typical halogen acceptors of the hydrazine type represented by Formula C are disclosed in Ives, US. Patent 2,588,982, issued Mar. 11, 1952. Typical halogen acceptors of the type represented by Formula D are the urazole and thiourazole halogen acceptors disclosed in Bacon and Illing'swo'rth application, U.S. Ser. No. 406,186 filed Oct. 23, 1964.

'Examples of specific nitrogen-containing halogen acceptors that are useful in the invention are set out below.

1 ,3-dimethyl-Z-imidazolidinethione Z-imidazolidinethione 1-phenyl-5-mercaptotetrazole Thiosemicarbazide Tetramethylthiourea p-dimethylaminobenzaldehyde-thiosemicarbazone l-isopentyl-Z-thiourea 1-(2-diethylaminoethyl) -1,2,5,6-tetrahydro-l-3,5-triazine-4-thiol 1 ,2-bis( 1,2,5 ,6-tetrahydro-l ,3,5-triazine-4-thiol) ethane l-phenyl-Z-thiourea 1 ,3-diphenyl2-thiourea 4-thiobarbituric acid 2-thiouracil l-acetyl-2-thiourea 1,3-dibenzyl-2-thiourea 1, l-diphenyl-Z-thiourea l-ethyl-1-(a-naphthyl)-2-thiourea Z-mercaptoimidazole 5-selenourazole Hydrazine Phenylhydrazine hydrochloride 2,5-dichlorophenyl hydrazine 1-phenyI-Z-imidazolidinethione 4,5-diphenyl-4-imidazolidine-Z-thione 1-methyl-2-mercaptoimidazole l-n-butyl-l ,2,5 ,6-tetrahydrol 3 ,5 -triazine-4-thiol p-toluene sulfonyl hydrazine Hexylhydrazine Thiourea l-methyl-Z-imidazolidinethionc D-mannose thiosemicarbazone Morpholino-Z-propane thiosemicarbazone D-galactose thiosemicarbazone Urazole 3-thiourazole 3,5-dithiourazole 3,5-dithiourazole hydrazine salt 4-aminourazole hydrazine salt 3,5-dithiourazole hydrazine salt Urazole sodium salt 4-(1-naphthyl)urazole 4-ethylurazole l-phenylurazole 4-phenylurazole l-butylurazole 1-octylurazole 4-butyl-3,5-dithiourazole 1,4-diphenylurazole 1,4-dibutylurazole 1,4-dibutyl-3,S-dithiourazole 1,4-diphenyl-3,S-dithiourazole 1-ethyl-4-phenylurazole 1-ethyl-4 phenyl-3,5-dithiourazole 3-thio-5-iminourazole p-tolyhydrazine hydrochloride u-naphthylhydrazine a-benzyl-a-phenylhydrazine Such ureas, which include thioureas, urazoles, etc., as well as cyclic forms thereof, are merely illustrative halogen acceptors.

Other typical halogen acceptors that can be used in the invention include stannous salts such as stannous chloride as disclosed in Hunt, US. Patent 3,033,678 issued May 8, 1962; aromatic mercaptans such as thiosalicylic acid; hydroquinones such as hydroquinone, chlorohydroquinone, gentistic acid and t-butylhydroquinone; catechols such as phenyl catechol and t-butylcatechol; paminophenols such as N-methyl-p-aminophenol sulfate; 3-pyrazolidones such as 1-phenyl-3pyrazolidone, 4-methyl-l-phenyl-B-pyrazolidone and 1-phenyl-4,4-dimethyl-3- pyrazolidone; phenylenediamines; nitriles; phenols; glycine; sodium sulfite; alkaline materials such as borax, alkali metal hydroxide, etc.; and the like halogen acceptors well known to those skilled in the art.

The concentration of halogen acceptor utilized in the emulsions of the invention can be widely varied in accordance with usual practice. Usually, about .01 to mole percent, and more generally about .1 to 25 mole percent, based on the silver halide in the emulsion is utilized.

The halogen acceptors are utilized contiguous to the silver halide in the present photographic system. Such halogen acceptors can be incorporated in the same photographic layer as the silver halide such as in the same emulsion layer, or in a layer adjacent to the silver halide.

The photographic silver halide system of the inven tion can comprise layers coated on a wide variety of supports in accordance with usual practice. Typical suitable supports include paper, polyethylene-coated paper, polypropylene-coated paper, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film, and related films of resinous materials, as well as glass, metals and others.

The following examples illustrate preferred embodiments of the invention.

Example 1 A radiation-sensitive gelatino silver chlorobromide (5 mole percent chloride and 95 mole percent bromide) photographic emulsion having an average grain size of about .06 micron was prepared by slowly adding simultaneously an aqueous solution of silver nitrate and an aqueous solution of alkali metal halides to an agitated aqueous gelatin solution containing 122 mg. of bismuth nitrate pentahydrate per silver mole at 60 C. at a pH of about 2.0 adjusted with nitric acid. About 5.0 mole percent of the halogen acceptor dithiourazole hydrazine salt, based on the silver, was added to the emulsion and thereafter the emulsion was coated on a photographic paper support. The resulting prepared photographic element was a print-out paper that can be utilized to prepare visible images without a photodevelopment or chemical development step by exposure to suflicient light.

(A) High intensity exposure to produce visible image directly.A print-out image was obtained by image exposing a sample of the prepared photographic element to tungsten illumination of 400,000 foot-candle seconds (5 minutes to 1380 foot-candles). A reflection density of 1.44 was produced by photolysis under roomlight conditions. An area of the same photographic element which was not exposed to light had a reflection density of 0.09. The image discrimination of the exposed photographic element is 1.35 density units (1.44-0.09).

(B) Latent image exposure+heat treatment-i-photodevelopment to produce visible image.Another sample of the above-described photographic element image-exposed in accordance with the invention to tungsten illumination to give an exposure of 240 foot-candle seconds (20 seconds to 12 foot-candles). No visible image on the image-exposed photographic element was apparent. The resulting sample with an area having this latent image exposure and an area with no exposure was heated by holding it in contact with a metal platen at 530 F. for 2 seconds in the dark. The sample was then exposed uniformly to tungsten illumination to give an exposure of 400,000 foot-candle seconds to photodevelop the latent image. The area given the latent image exposure was darkened to give a reflection density of 1.25. The area receiving no latent image exposure was darkened only slightly by the exposure of 400,000 foot-candle seconds, the reflection density being 0.33. The image discrimination of this photographic element was 0.92 density units (1.250.33). When the heat treatment step before the photolysis step is omitted, the entire emulsion area of the photographic element prints out to uniform density, there being no differentiation between image and nonimage areas.

These data demonstrate that a density ditference of the magnitude usually associated with print-out papers can be achieved in a paper given only a latent image exposure if the paper is heated to a high temperature prior to overall photolysis.

Example 2 Two photographic elements of the type described in Example 1 and treated as described in Example 1A and Example 1B were prepared and designated Element A and Element B in Table I below.

(a) Element A.Visi'ble image prepared directly with intensity image exposure (a print-out image).

(b) Element B.--Visible image prepared 'by latent image exposure+heat treatment+photodevelopment (exposure in accordance with the invention).

Both Element A and Element B were exposed for 2 minutes to 1600 foot-candles of illumination from a white flame arc lamp. The reflection densities of exposed and unexposed areas (image and non-image areas) were measured before and after the arc lamp exposure.

TABLE I Before arc lamp After are lamp exposure exposure Element A:

Exposed area. 1. 44 1. 55

Unexposed area 0.09 1. 46

Discn'minatiom 1. 35 0. 09 Element B:

Exposed area 1.25 1. 34

Unexposed area. 0. 33 0. 43

Discrimination 0. 92 0. 91

The data set out in Table I illustrates the improved light stability of images processed in accordance with the invention with a print-out photographic system.

EXAMPLE 3 TABLE II Unexposed area Discrimination Platen temp, degrees F.

Exposed area The data in Table II illustrate that heating times of one minute at temperatures of at least about 300 F. are used to achieve any significant image discrimination.

EXAMPLE 4 TABLE III Trivalent metal salt: Concentration (mg/Ag. mole) (NI-I RhCl 1.0 (NH RhCl 5.0 (NH RhCl 25.0 K IrCl 10.0

The various emulsions were coated on photographic paper supports, image exposed, heated and thereafter photodeveloped to form visible images in the areas of exposure as described in Example 1B.

The present invention thus provides a process for utilizing normally nonlatensifiable silver halide print-out materials for preparing photodeveloped images having high stability.

The invention has been described in considerable 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.

I claim:

1. A photodevelopment process for preparing visible silver photographic images in a fine-grain silver halide photographic print-out material comprising silver halide grains which have trivalent metal ions occluded therein, said grains having been formed in an acidic media, and wherein said silver halide grains have a halogen acceptor contiguous thereto; said process comprising imagewise exposing said silver halide to form a latent image, heating said exposed silver halide to at least about 300 F. to repress printing out of unexposed areas of said silver halide and thereafter uniformly exposing said heated silver halide to light to produce a visible silver image.

2. A process as described in claim 1 wherein said halogen acceptor is a nitrogen-containing halogen acceptor.

3. A process as described in claim 1 wherein said trivalent metal ions are selected from the group consisting of bismuth, iridium and rhodium.

4. A process as described in claim 1 wherein said trivalent metal ions are bismuth ions.

5. A process as described in claim 1 wherein said trivalent metal ions are rhodium ions.

6. A process as described in claim 1 wherein said trivalent metal ions are iridium ions.

7. A process as described in claim 1 wherein said silver halide print-out material is a gelatino silver chlorobromide emulsion in which said silver chlorobromide has an average grain size of less than about .2 micron.

8. A process as described in claim 1 wherein said silver halide grains are formed in the presence of trivalent metal ions.

9. A photodevelopment process for preparing visible silver photographic images in a fine-grain silver halide photographic print-out material comprising trivalent metal ion-containing silver halide grains, said grains having been formed in an acidic media, and wherein said silver halide grains have a halogen acceptor contiguous thereto; said process comprising imagewise exposing said silver halide to form a latent image, heating said exposed silver halide to at least about 300 F to repress printing out of unexposed areas of said silver halide and thereafter uniformly exposing said heated silver halide to light to produce a visible silver image.

10. A photodevelopment process for preparing visible silver photographic images in a silver halide photographic print-out emulsion comprising silver halide grains having an average size of less than about .2 micron and having 4 occluded bismuth ions therein, wherein said grains are formed in an acidic media, and wherein said grains have a halogen acceptor contiguous thereto; said process comprising imagewise exposing said silver halide to form a latent image, heating said exposed silver halide to at least about 300 F. to repress printing out of unexposed areas of said emulsion and thereafter exposing said heated silver halide to light to produce a visible silver image.

11. A process as described in claim 10 wherein said halogen acceptor is a nitrogen-containing halogen acceptor.

12. A process as described in claim 10 wherein said halogen acceptor is a thiourazole.

13. A process as described in claim 10 wherein said halogen acceptor is dithiourazole hydrazine salt.

14. A process as described in claim 10 wherein said silver halide grains are formed in the presence of bismuth 15. A process as described in claim 10 wherein the silver halide print-out emulsion is a gelatino silver chlorobromide emulsion comprising at least mole percent bromide.

16. A process as described in claim 10 wherein the silver halide emulsion is coated on a paper support.

17. A process as described in claim 10 wherein said silver halide emulsion is coated on a polyethylene terephthalate support.

References Cited UNITED STATES PATENTS 2,448,060 8/1948 Smith et al 96-108 2,717,833 9/1955 Wark 96-108 3,241,971 3/1966 Kitze 96-108 3,287,137 11/1966 McBride 96-108 956,567 5/1910 Caldwell 96-107 3,033,678 5/1962 Hunt 96-119 3,144,336 8/1964 Herz 96-108 FOREIGN PATENTS 1,177,004 8/1964 Germany.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner.

US. Cl. X.R. 96-107, 108