CA1051706A - Transition metal photoreduction systems and processes - Google Patents

Abstract

Abstract of the Disclosure A radiation-sensitive element is disclosed including a radiation-sensitive layer comprised of a cobalt(III)complex and a photoreductant. A process is disclosed in which the photoreductant is converted to a reducing agent by exposure to electromagnetic radiation longer than 300 nanometers. The reducing agent is then reacted with a cobalt(III)complex.
Images can be recorded directly within the radiation-sensitive layer or in a separate image-recording element or layer by use of the residual cobalt(III)complex not exposed or one or more of the reaction products produced by exposure. By using the ammonia liberated from ammine ligand containing cobalt(III)-complexes on exposure in combination with imagewise and uniform exposures, positive or negative images can be formed in diazo image-recording layers or elements associated with the radiation-sensitive layer.

Description

~L~517~6 This invention is directed to a process and element capable of forming a use~ul redox couple in response to actinic radiation in excess of 300 nanometers in wavelength. More specifically, this invention is directed to a photographic process and element capable of selectively generating a useful redox couple through the interaction of a cobalt(III)complex and a photoreductant. The present invention is further con-cerned with a photographic element and process capable of`
forming a photographic image in either a photographic element or layer containing the redox couple or in a separate, contiguous photographic element or layer.
Classically, photographic elements have incorporated silver halide as a radiation-sensitive material. Upon exposure and processing the silver is reduced to its metallic form to produce an image. Processingg with its successive aqueous baths~ has become increasingly objectionable to users desiring more immediate availability of a photographic image.
Despite the processing requlred, silver halide photography has remained popular~ since it offers a number of distinct advantages. For example, although silver halide is itself photoresponsive only to blue and lower wavelength radiation, spectral sensitizers have been found which, without directly chemically interactingg are capable of transferring higher wavelength radiation energy to sllver halide to render it panchromatic. Addltlonally, silver halide photography is attractive because of its comparatively high speed. Frequently, silver halide is referred to as exhibiting internal amplifica-tlon--i.e., the number of silver atoms reduced in imaging is a large multiple of the number Or photons received.
~; 30 A variety of ~onsilver photographic systems have been considered by;those skilled in the art. Typically these

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systems have been chosen to minimize photographic processing and to provide useable photographic images with less delay than in silver halide photography. Characteristically, these systems require at least one processing step to either print or fix the photographic image. For example, ammonia or heat processing has bee~ widely used in diazo imagi~g syste~s While advantageously simple in terms of processing, these systems have, nevertheless, exhibited signlficant disadvantages. For example, many nonsilver systems are suitable for producing only negative images (or only positive images). Further, these systems have been quite slow, since they have generally lacked the internal amplification capability of silver halide. Many systems have also suffered from diminishing image-background contrast with the passage of time.
The use of cobalt(III)complex compounds in photographic elements is generally known in the art. For example, Shepard et al U.S. Patent 3,152,903 teaches imaging through the use of an oxidation-reduction reaction system that requires a photocatalyst. The solid reducing agent is taught to be any one of a number of hydroxy aromatic compounds, including dihydrophenols, such as hydroquinone. The oxidant is taught to be chosen from a variety o~ metals, such as silver, mercury, lead, gold, manganese, nickel, tin, chromium, platinum, and copper. Shepard et al does not specifically teach the use of cobalt(III)complexes as oxidants. Instead, Shepard et al teaches that photochromic complexes, such as cobalt ammines, can be employed as photocatalysts to promote the oxidation-reduction reaction.
Cobalt(III)complexes are known to be directly responsive to electromagnetic radiation when suspended in .

solution. While most cobalt(III)complexes are pre~erential]y ' .:

responsive to ultraviolet radiation below about 300 nanometers, a number o~ cobalt(III)complexes have been observed in solu-tion to be responsive to electromagnetic radiation ranging well into the visible spectrum. Unfortunately, these same complexes when incorporated into photograpnic elements lose or are diminished in their ability to respond directly to longer wavelength radiation. For example, Hickman et al in U.S. Patent 1,897,843 teaches mixing thio-acetamide with hexamino cobaltic chloride to form a light-sensitive complex capable of interacting with lead acetate to produce a lead sulfide image. Hickman et al U.S. Patent 1,962,307 teaches mixing hexammine cobaltic chloride and citric acid to form a light-sensitive complex capable of bleaching a lead sulfide image. Weyde in U.S. Patent 2,084,420 teaches producing a latent image by exposing Co(NH3)2(N02)4NH4 to light or an electrical current. A visible image can be formed by subsequent development with ammonium sulfide. In each of the above patents there is no photoreductant preæen-t. ~-Borden in U.S. Patent 3,567,453, issued March 2, 1971, and in his article "Review of Light-Sensitive Tetraarylborates", - Photographic Science and Engineerin~, Volume 16, No. 4, July-August 1972, discloses that aryl borate salts incorporating a wide variety of cations can be altered in solvent solubility upon exposure to actinic radiation. Borden demonstrates the general utility of aryl borate salts as radiation-sensitive compounds useful in forming differentially developable coat-ings, as lS typical of lithography, by evaluatlng some 400 - di~ferent cations~ranging from organic cations~ such as dlazonium, acridinium and pyridinium salts, to inorganic cations, such as cobalt hexammine. Borden discloses that the aryl borate salts can be spectrally sensitized with a variety ' ... , . .~

~5~7CD6 oE sensitizers, including quinones. In its unsensitized form the cobalt hexam-nine ~etraphenyl borate of Borden is reported to be light sensitive in the range of from 290 to 430 nano-meters. Borden notes in his report that hexammino cobalt chloride, although bright orange and therefore absorptive in the visible spectrum, is not useful in the lithographic system discussed in his article. Thus, Borden relies upon the light-sensitive aryl borate anionic moiety to provide radiation sensitivity.
In Resear~h Disc~Q~ure, Vol. 126, October, 1974, Publication No. 12617, and Canadian Serial Nos. 204,033 and 204,201, filed July 4, 1974 and July 5, 1974, respectively, it is taught to reduce tetrazolium salts and triazolium salts to formazan and azo-amine dyes, respectively, employing in the presence of labile hydrogen atoms a photoreductant which is capable of forming a reducing agent precursor upon exposure to actlnic radiation. The reducing agent precursor is converted to a reducing agent by a base, such as ammonia.
In one aspect of the invention there is provided a radiation-sensitive element comprislng a support and, as a coating, a radiatîon-sensitive layer comprised of a cobalt(III)-complex free of a sensitlzable anion and a pllotoreduçtant capable of forming a redox couple wi~h the cobalt(III)complex upon exposure to actinic radiation longer than 300 nanometers in wavelength.

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, ~ ' ~5~L7~6 In another aspect this invention is directed to a process comprising converting a photoreductant to a reducing agent by exposure to electromagnetic radiation of' a wave-length longer than 3OO nanometers. The reducing agent is then reacted with '1 cobalt(III)complex free of a sensitizable anion.
In still another aspect this invention is directed to a process comprising exposing a radiation-sensitive layer containirlg a photoreductant and a ligand containing cobalt(III)-complex to electromagnetic radiation of a wavelength longer than 3OO nanometers to convert the photoreductant to a reducing agent. The radiation-sensitive layer is associated with an image-recording layer which is visibly~responsive to at leas-t one ligand contained wi-thin the cobalt(III)complex upon release thereof. The radiation-sensitive layer is then heated to s-timu-late reduction of the cobalt(III)complex with concomitant ligand release and transfer of the released ligand to the image-recording layer.
In an additional aspect this invention is directed to a process of formlng positive images by imagewise exposing a radiation-sensitive layer containing a photoreductant and a cobalt(III)complex to radlation longer than 300 nanometers ln wavelength to convert the photoreductant to a reducing agent. The radiation-sensitive layer is heated to stimul'ate reduction of the cobalt(III)complex in exposed areas. There-after, leuco dye means is introduced into the radiation-sensitive layer and the leuco dye means is imagewise oxidized to a colored form by the cobalt(III)complex remaining in : :
. .

.

~S~IL7~36 unexposed areas of the radiation-sensitive layer to form a positive image.
This invention can be better understood by re~erence to the following detailed description considered in conjunction with the accompanying drawings, in which Fig. 1 is a schematic diagram of a radiation-sensitive element according to this invention;
Fig. 2 is a schematic diagram of the radiation-sensitive element in combination with an original image-bearing element receiving a reflex exposure~
Fig. 3 is a schematic diagram`of the radiation-sensitive element in combination with a copy sheet receiving thermal processing;
Fig. 4 is a schematic diagram of the `imaged copy sheet;
Fig. 5 is a schematic diagram of a composite radiation-~ sensitive imaglng element; and Figs. 6 and 7 are schematic diagrams o~ an original image-bearing element and an image-bearing radiation-sensitive composite.
Cobalt(III)Complexes The cobalt(III)complexes employed in the practice of th1s inven-tion are those which feature a molecule having a cobalt atom or ion surrounded by a group of atoms, ions or other molecules which are generically referred to as ligands.
The cobalt atom or ion in the center of these complexes is a Lewls acid while the ligands~are Lewis bases. While it is known that cobalt is capable of forming complexes in both , - its divalent and trivalent forms, trivalent cobalt complexes--iOe., cobalt(~III)complexes--are~employed in the practice of ~thls invention, since~the ligands are~ tenaciously held in ~these~complexes as compared to corresponding cobalt(II)complexes.

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~ 5~7~6 Preferred cobalt(III)complexes are those which are inert.
Inert complexes are defined as those which, when a test sample thereof is dissolved a-t 0.1 molar concentration at 20C in an inert solvent solution also containing a 0.1 molar concentration of a tagged uncoordinated ligand of the same species as the coordinated ligand, exhibit essentially no exchange of uncoordinated and coordinated ligands for at least one minute, and preferably for at least several hours, such as up to five hours or more. This test is advantageously conducted under the conditions existing within the radiation-sensitive elements of this invention. ~any cobalt(III)-complexes show essentially no change of uncoordinated or coordinated ligands for several days. The definition of inert complexes, and the method of measuring ligand exchange using radioactive isotopes to tag ligands are well known in the art.
See, for example, Taube, Chem. Rev., Vol. 50, p. 69 (1952) and Basolo and Pearson, Mechanisms of Inorganic Reactions, A Study of Metal Complexes and Solutions, 2nd Edition, 1967, published by John Wiley and Sons, page 141. Further details on measurement of ligand exchange appear in articles by Adamson èt al, J. Am. Chem., Vol. 73, p. 4789 (1951).
Preferred cobalt(III)complexes useful in the practice of this invention are those having a coordination number of 6. A wlde variety of ligands can be used with cobalt(III) to form cobalt(III)complexes. Nearly all Lewis bases (i.e. substances having an unshared pair o~
eIectrons) can be l~gands in cobalt(III)complexes. Some typical useful ligan~s include halides (e.g., chloride~
bromide,~fluoride), nitrate, nitrite, superoxide, water, amines (e.g., ethylenediamine, n-propylene diamine, diethyl-enetriamine, triethylenetetraam me, diaminodiacetate, ethyl-~5~71~6 enediamine-tetraacetic acid, etc.), ammine, azide, glyoximines, thiocyanate, cyanide, carbonate, and similar ligands, including those referred to on page 44 of Basolo et al, supra.
It is also contemplated to employ cobalt(III)complexes incorporating as ligands Schi~f bases, such as those dis-closed in German OLS Patents 2,052,197 and 2,052,198 The cobalt(III)complexes useful in the practice of this invention are those which are free of sensitizable anions. In one form the cobalt(III)complex can be a neutral compound which ls entirely free of either anions or cations.
The cobalt~III)complexes can include one or more cations or nonsensitizable anions as determined by the charge neutraliza-tion rule. Useful cations are those which produce readily solubilizable cobalt(III)complexes, such as alkali and quaternary ammonium cations. Anions are considered to be sensitizable for purposes of this invention if their use in combination wi-th known sensitizers for silver halide emulsions stimulates their photographic response upon exposure to electromagnetic radiation longer than 300 nanometers in wavelength. Such anions can, of course, be readily identified to be sensltizable by observing their behavior in combination with photolytically inactive cations with and without known spectral sensitizers being present. Especially useful with :
cobalt(III)complexes are nonsensitizable anions, such as halldes (e.g., chloride, bromide, fluoride~ etc.), sulfite, ~sulfate, alkyl or aryl sulfonates, nitrate, nitrite, per-chlorate, carboxylates (e~g., halocarboxylates, acetate, hexanoate, etc.), hexafluorophosphate, tetrafluoroborate, as well as other, similar, nonsensitizable anions. Preferred ~cobalt(III)complexes are those which, in accordance with the charge neutralization rule, incorporate nonsensitizable anions ;: :
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,.. .. . . ,; , , , ; . . ~ . ` . . , . ,' ' ... ' .,, . ', .. , ; . .

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having a net negative charge of' 3.
In systems of the type disclosed by Thap DoMi.nh in commonly assigned U.S. Patent No. 4,075,019, titled HIGH GAIN
TRANSITION METAL COMPLEX IMAGING, cobalt(III)complexes incorporating anions of acids having pKa values of 3.5 or less (preferably from 3.0 to O.O), when employed with certain compounds containing conjugated ~ bonding systems capable of forming Co(III) ligands, exhibit remarkable increases in imaging capabilities, probably due to catalysis of image-producing cobalt(III)complex generation.
Exemplary preferred cobalt(III)eomplexes useful in the practice of this invention are those set forth in Table I.

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TABLE I
Exemplary Pre~erred CobaltlIII)Complexes C- 1 hexa-ammine cobalt(III) acetate C- 2 hexa-ammine cobalt(III) thiocyanate C- 3 hexa-ammine cobalt(III) trifluoroacetate C- ~ chloropenta~ammine cobalt(III) bromide C- 5 bromopenta-ammine cobalt(III) bromide C- 6 aquopenta-ammine cobalt(III) nitrite C~ 7 bis(ethylenediamine) di-ammine cobalt-(III) perchlorate C- 8 bis(ethylenediamine) diace-~tato cobalt-(III) chloride C- 9 triethylenetetramine dichloro cobalt(III) acetate C-10 bi.s(methylamine) tetra-ammine cobalt(III) hexafluorophosphate C-ll aquopenta(methylamine) cobalt(III) nitrate C-12 chloropenta(ethylamine) cobalt(III) :
chloride C-13 trinitrotris-ammine cobalt(III) C-14 trinitrotrls(methylamine) cobalt(III) C-15 tris(ethylenediamine) cobalt(III) acetate C-16 tris(1,3-propanediamine) cobalt(III) tri-fluoroacetate C-17 bis(dimethylglyoxime) bispyridine cobalt-(III) trichloroacetate C-18 N,N~-ethylenebis(salicylideneimine) bis-ammine cobalt(III) bromide . . .
C-I9 bis(dimethylglyoxime) ethylaquo cobalt- . .

C-20 J~-superoxodeca-ammine dicobalt(III) perchlorate ~.
C-21: sodium dichloro ethylenediamine diaceto cobalt(III) : ', ~ :.

~L~5~7~;
TABLE I Cont.
Exemplary Preferred Cobalt(III)Complexes C-22 penta-ammine carbonato cobalt(III) nitrite C-23 tris(glycinato) cobalt(III) C-24 trans[bis(ethylenedia~line) chlorothio-cyanato cobalt(III)] sulfite C-25 trans[bis(ethylenediamine) diazido cobalt(III)] chloride C-26 cis[bis(ethylenediamine) ammine azido cobalt(III)hexanoate C-27 tris(ethylenediamine) cobalt(III) chloride C-28 trans[bis(ethylenediamine) dichloro cobalt(III)] chloride C-29 bis(ethylenediamine) dithiocyanato cobalt(III) fluoride C-30 triethylenetetramine dinitro cobalt-(III) iodide C-31 tris(ethylenediamine) cobalt(III) 2-pyridylcarboxylate ~61 5 3L~
Photoreductan-ts As employed herein, the term "photoreductant"
designates a material capable of molecular photolysis or photo-induced rearrangement to generate a reducing agent, which forms a redox couple with the cobalt(III)complex. The reducing agent spontaneously or with the application of heat reduces the cobalt(III)complex. The photoreductants employed in the practice o~ this invention are to be distinguished from spectral sensitizers, such as those disclosed in commonly assigned, concurrently ~iled Canadian patent application Serial No. 221,818, titled Spectral Sensitization of Transition Metal Complexes. While spectral sensitizers may in fact form a redox couple for the reduction of cobalt(III)complexes (although this has not been confirmed), such sensitizers must be associated with the cobalt(III)complex concurrently with receipt of actinic radiation in order for cobalt(III)complex reduction to occur. By contrast, when a photoreductant is first exposed to actinic radiation and thereafter associated with a cobalt(III)complex, reduction of the cobalt(III)complex still occurs.
Any photoreductant as defined above can be usefully employed in the practice of this invention. A variet~ of compounds are known in the art to be photoreductants. For example, diazonium salts are known photoreductants. In Research Disclosure3 Vol. 126, October, 1974, Publication No.
12617, and Canadian Serial Nos. 20L~,033 and 204,201, filed July 4, 1974 and July 5, 1974, respectively, cited above and here incorporated by reference, a large variety of photo-reductants are disclosed which are useful in the prac-tice of this invention. We have observed quinone, disulfide, diazo-anthrone, diazonium salt, diazophenanthrone and aromatic azide, carbazide and diazosulfonate photoreductants to be ~5:L'7~q6 particularly preferred for use in the practice of thisinvention.
The disul~ide photoreductants of this invention are preferably aromatic di-sulfides containing o~e or two aromatic groups attached to the sulfur atoms. The nonaromatic group can take a variety of forms, but is preferably a hydro-carbon group, such as an alkyl group having from 1 to 20 (preferably 1 to 6) carbon atoms. The aromatic groups of the di-sulfide, azide, carbazide and diazosulfonate photoreductants can be either single or fused carbocyclic aromatic ring structures, such as phenyl, naphthyl, àhthryl, etc. They can, alternatively, incorporate heterocyclic aromatic ring structures, such as those having 5- or 6-membered aromatic rings i~cluding oxygen, sulfur or nitrogen heteroatoms. The aromatic rings can, of course, bear a variety of substituents.
Exemplary of specifically contemplated ring substituents are lo~er alkyl (i.e., 1 to 6 carbon atoms), lower alkenyl (i.ec, 2 to 6 carbon atoms), lower alkynyl (i.e., 2 to 6 carbon atoms), benzyl, styryl, phenyl, biphenyl, naphthyl, alkoxy (e.g., methoxy, ethoxy, etc~), aryloxy (e.g., phenoxy), carboalkoxy (e g., carbomethoxy, carboethoxy, etc.), carboaryloxy (e.g., carbophenoxy, carbonaphthoxy), acyloxy (e.g., acetoxy, benzoxy, etc.), acyl (e.g., acetyl, benzoyl, etc.), halogen (i.e., fluoride, chloride, bromide, iodide), cyano, azido, nitro, haloalkyl (e.g., trirluoromethyl, trifluoroethyl, etc.), amino (e.g., dimethylamino), amido (e.g., acetamido, benzamido), ammonium (e.g., trimethylammonium), azo (e.g., phenylazo), - ~ sulfonyl (e.g., methylsulfonyl, phenylsulfonyl), sulfoxy (e.g., methylsulfoxy), sulfonium (e.g., dimethyl sulfonium), silyl (e.g., trimethylsilyl) and thioether (e.g., methyl mercapto) substituents.

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: '' ~353L7~6i Specific exemplary di-sulfides, diazoanthrones, diazophenanthrones, aromatic carbazides, aromatic azides, diazonium salts and aromatic diazosul~onates are set forth in Table II.
TABLE II
Exemplary Photoreductants PR- 1 l-naphthyl disulfide PR- 2 ~-naphthyl disulfide PR- 3 9-anthryl disulfide PR- 4 cyclohexyl 2-naphthyl disulfide PR- 5 diphenylmethyl 2-naphthyl disulfide PR- 6 2-dodecyl lt-naphthyl disulfide PR- 7 thioctic acid PR- 8 2,2'-bis(hydroxymethyl)diphenyl disulfide PR- 9 10-diazoanthrone PR-10 2-methoxy-10-diazoanthrone PR-ll 3-nitro-10-diazoanthrone PR~-12 3,6-diethoxy-10-diazoanthrone PR-13 3-chloro-10-diazoanthrone PR-14 4-ethoxy-10-diazoanthrone PR-15 4-(1-hydroxyethyl)-10-diazoanthrone .
:PR-16 237-dlethy1 10-diazoanthrone PR-17 9-diazo-10-phenanthron0 PR 18 3,6-dimethyl-9-diazo-10-phenanthrone PR-19 2,7-dimethyl-9-diazo-10-phenanthrone PR-20 4-azidobenzoic acid , .
PR-21 4-nitrophenyl azide .

PR-22 4-dimethylaminophenyl azide PR-23 2,6-di-4-azidobenzylidene~4-methyl-: 30 cyclohexanone .
PR-24 2-azido-1-octylcarbamoyl-benzimidazole ~ ~ .
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TABLE II Cont.
Exemplary Photoreductants PR-25 2,5-bis(4-azidophenyl.)-1,3,4-oxadiazole PR-26 1-azido-4-methoxynaphthalene PR-27 2-carbazido-l-naphthol PR-28 3,3'-dimethoxy-4,4'-diazidobiphenyl PR-29 4-diethylaminobenzenediazonium tetra-fluoroborate PR-30 2,5-dimethoxybenzenediazonium tetra-~luoroborate PR-31 2,5-diethoxybenzenediazonium tetra-fluoroborate PR-32 255-diethoxy-4-morpholinobenzenediazonium tetrafluoroborate PR-33 4-chloro-2,5-diethoxybenzenediazonium tetrafluoroborate PR-34 4-dimethylaminobenzenediazonium tetra-fluoroborate PR-35 2-ethoxy-4-diethylaminobenzenediazonium tetrafluoroborate . .
PR-36 4-(ethylamino)benzenediazonium tetra-- fluoroborate PR-37 4-[bis(hydroxypropyl)amino~benzenedi-azonium tetrafluoroborate PR-38 2-ethoxy-4-diethylaminobenzenediazonium tetrafluoroborate PR-39 4-(N-methyl-N-aIlylamino)benzenediazonium tetrafluoroborate PR-40 4-(diamylamino)benzenediazonium tetra-

3 fluoroborate : PR-41 2-methyl-4-diethylaminobenzenediazonium tetrafluoroborate PR-42 4-(oxazolidino)benz0nediazonium tetra-: fluoroborate:
PR-43 4-(cyclohexylamino)benzenediazonium tetra-fluoroborate PR-44 2-nitro-4-morpholi.nobenzenediazonium hexa-fluorophosphate PR-45 4-(9-carbazolyl~benzenediazonium hex-fluorophosphate - -:~ :PR-46 4-(dihydroxyethylamino)-3-methylbenzene- :
: : diazonium hexfluorophosphate PR-47 4-diethylaminobenzenediazonium hexa-chlorostannate ~S~7(~6 TABLE II Cont.
Exemplary Photorecluctants PR-48 4-dimethylamino-3-methylbenzenediazonium hexachlorostannate PR-49 2-methyl-4-(N-methyl-N-hydroxypropyl-amino)benzenediazonium hexachlorostannate PR-50 4-dimethylaminobenzenediazonium tetra-chlorozincate PR-51 4-dimethylamino-3-ethoxybenzenediazonium chlorozincate PR-52 4-diethylaminobenzenediazonium tetra-chlorozincate PR-53 4-diethylaminobenzenediazonium hexa-~luorophosphate PR-54 2-carboxy-4-dimethylaminobenzenediazonium hexafluorophosphate PR-55 3-(2-hydroxyethoxy)-4-pyrrolidinobenzene-diazonium hexafluorophosphate PR-56 4-methoxybenzenediazonium hexafluoro-phosphate PR-s7 2,5-diethoxy-4-acetamidobenzenedi-azonium hexafluorophosphate PR-58 4-~ethylamino-3-ethoxy-5-chlorobenzene-diazonium hexafluorophosphate pR-sg 3-methoxy-4-diethylaminobenzenediazonium hexafluorophosphate PR-60 2,5-dichloro-4-benzylaminobenzenedi- :
azonium hexafluorophosphate PR-61 4-phenylaminobenzenediazonium hexafluoro-phosphate ~ :
PR 62 4 (tert.-butylamino)benzenediazonium : hexafluorophosphate PR-63 4-morpholinobenzenediazonium hexa~luoro-phosphate PR-64 4-morpholino-3-methoxybenzenediazonium hexafluorophosphate PR-65 1-piperidinoisoquinolin-4-yldiazonium hexa-fluorophosphate PR-66 4-morpholino-2,5-dimethoxybenzenedi-azonium hexafluorophosphate PX-67 4-morpholino-2-ethoxy-5-methoxybenzene-diazonium hexa~luorophosphate ~S~6 TABLE II Cont.
Exemplary Photoreductants PR-68 4-(4-methoxyphenylamino)benzenediazonium chlorozincate PR-69 4-morpholino-2,5-dibutoxybenzenedi azonium chlorozincate PR-70 2,5-diethoxy-4-benzoylaminobenzenedi-azonium chlorozincate PR-71 2~5~dibutoxy-4- benzoylaminobenzenedi-azonium chlorozincate PR-72 4-ethylmercapto-2,5-diethoxybenzene~
diazonium chlorozincate PR-73 4-tolymercapto-2,5-diethoxybenzenedi-azonium chlorozincate PR-74 potassium 4-(N-ethyl-N-hydroxyethyl! -amino)-benzenediazosulfonate PR-75 sodium 4-(diethylamino)benzenediazo-sulfonate PR-76 potassium 2-chloro-4-morpholinobenzene-diazosulfonate PR-77 tetramethylammonium 3-methoxy-4-piper-idinobenzenedi~zosulfonate ~: ~

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~ ~ ' ~351~7~6 Quinones are useful as photoreductants in the practice of this invention. Preferred quinones include ortho-and para-benzoquinones and ortho- and para-naphthoquinones~
phenanthrenequinones and anthraquinones. The quinones may be unsubstituted or incorporate any substituent or combination of substituents that do not interfere with -the conversion o~
the quinone to the corresponding reducing agent. A variety of such substituents are known to the art and include, but are not limited to, primary, secondary and tertiary alkyl, alkenyl and alkynyl, aryl, alkoxy, aryloxyg aralkoxy, alkaryloxy, hydroxyalkyl, hydroxyalkox~, alkoxyalkyl, acyloxyalkyl, aryloxyalkyl, aroyloxyalkyl, aryloxyalkoxy, alkylcarbonyl, carboxyl, primary and secondary amino, amino-alkyl, amidoalkyl, anilino~ piperidino, pyrrolidino, morpholino~ nitro, halide and other similar substituents.
Such aryl substituents are preferably phenyl substituents and such alkyl, alkenyl and alkynyl substituents, whether present as sole substituents or present in combination with other atoms~ typically incorporate 20 (preferably 6) or fewer carbon atoms.
Specific exemplary quinones intended to be used in combination with a separate source of labile hydrogen atoms are set forth in Table III.

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~S~7~6 TABLE lII
Exemplary Quinones Use~ul With External Hydrogen Source PR-78 2,5-dimethyl-1,4-benzoquinone PR-79 2,6-dimethyl-1,4-benzoquinone PR-80 duroquinone PR-81 2~ formyl-1-methylethyl)-5-methyl-1,4-benzoquinone PR-82 2-methyl-1,4-benzoquinone PR-83 2-phenyl-1,4-benzoquinone PR-84 2,5-dimethyl-6-(1-formylethyl)-1,4-benzoquinone PR-85 2-(2-cyclohexanonyl)-3,6-dimethyl-1,4-benzoquinone PR-86 1,4-naphthoquinone PR-87 2-methyl-1,4-naphthoquinone PR-88 2,3-dimethyl-1,4-naphthoquinone PR-89 2,3-dichloro-1,4-naphthoquinone PR-90 2-thiomethyl-1,4-naphthoquinone PR-91 2-(1-~ormyl-2-propyl)-1,4-naphthoquinone -PR-92 2-(2-benzoylethyl)-1,4-naphthoquinone PR-93 9,10-phenanthrenequinone PR-94 2-tert-butyl-9,10-anthraquinone PR-95 2-methyl-1,4-anthraquinone PR-96 2-methyl-9,10-anthraquinone - ~-;' : ~ :.~, ., ~ -20- ;

~53L7~6 A preferred class of photoreductants are internal hydrogen source quinones; that is, quinones incorporating labile hydrogen atoms. These quinones are more easily photo-reduced than quinones which do not incorporate labile hydrogen atoms. Even when quinones lacking labile hydrogen atoms are e~ployed in combination with an external source of hydrogen atoms while incorporated hydrogen source quinones are similarly employed without external hydrogen source compounds, the internal hydrogen source quinones continue to exhibit greater ease of photoreduction. When internal hydrogen source quinones are employed with external hydrogen source compounds, their ease of photoreduction can generally be further improved, although the improvement is greater ~or t,hose internal hydrogen source quinones which are less effective when employed without an external hydrogen source compound.
Using quinones exhibiting greater ease of photo- -reduction results in photographic elements which exhibit improved image densities for comparable exposures and which produce comparable image densities with lesser exposure times. Hence, internal hydrogen source quinones can be employed to achieve greater photographic speeds and/or image densities.
Particularly preferred internal hydrogen source quinones are 5,8-dihydro-1,4-naphthoquinones having at least one hydrogen atom in each of the 5 and 8 ring positions~
Other preferred incorporated hydrogen source quinones are those which have a hydrogen atom bonded to a carbon a-tom to which is also bonded the oxygen atom o~ an oxy substituent or a nitrogen atom of an amine substituent with the further provision that the carbon to hydrogen bond is the third or -:

.. . : . ~ . ~ , . . . ~ , ~S~L7~Si forth bond removed from at least one quinone carbonyl doublebond. As employed herein the term "amine substituent" is inclusive of amide and imine substituents. Disubstituted amino substituents are preferred. 1,4-Benzoquinones and naphthoquinones ha~i~g one or more 1~- or 2t-hydroxyalkyl, alkoxy (including alkoxyalkoxy~-particularly 1l- or 2~-alkoxy-alkoxy, hydroxyalkoxy, etcO), 1'- or 2~-alkoxyalkyl, aralkoxy, 1~- or 2~-acyloxyalkyl, 1'- or 2~-aryloxyalkyl, aryloxyalkoxy, 1~- or 2~-aminoalkyl (preferably a 1~- or 2l-aminoalkyl in which the amino group contains two substituents in addition to the alkyl substituent), 1~- or 2l-aroyloxyalkyl, ~alkylarylamino, dialkyl-amino, N,N-bis-(l-cyanoalkyl)amino, N-aryl~N-(1-cyanoalkyl)amino, N-alkyl-N~ cyanoalkyl)amino, N,N-bis(l-carbalkoxyalkyl)-amino, N-aryl-N-(l-carbalkoxyalkyl)amino, N-alkyl-N-(l-carb-alkoxyalkyl)amino, N,N-bis(1-nitroalkyl)amino, N~alkyl-N-(l-nitroalkyl)amino, N-aryl-N-(l-nitroalkyl)amino, N,N-bis-(l-acylalkyl)amino, N-alkyl-N-(l-acylalkyl)amino, N-aryl-N-(l-acylalkyl)amino, pyrrolino, pyrrolidino, piperidino, and/or morpholino subs-tituen-ts in the 2 and/or 3 position are particularly preferred. Other substituents can, of course, be present. Unsubstituted 5,8-dihydro-1,4-naphthoquinone and 5,8-dihydro-1~4-naphthoquinones substituted at least in the 2 and/or 3 positlon with one or more of the above-listed preferred quinone substituents also constitute preferred internal hydrogen source quinones. It is recognized that ;- '' additional fused rings can be present within the incorporated hydrogen source quinones. For example, 1,4-dihydro anthra-quinones represent a useful species of 5,8-dihydro-1,4-naphthoquinones useful as incorporated hydrogen source quinones.
The aryl substituents and su'bstituent moieties of incorporated hydrogen source quinones are preferably phenyl or phenylene ~5~7~6 while the aliphatic hydrocarbon substltuents and substituentmoieties preferably incorporate twenty or fewer carbon atoms and, most preferably~ six or fewer carbon atoms. Exemplary preferred internal hydrogen source quinones are set forth in Table IV.

':

.,:

~5~7~6 TABLE IV
Exemplary Internal ~Iydrogen Source Quinones PR-97 5~8-dihydro-1,4-naphthoquinone PR-98 5,8-dihydro-2,5,8- trimethyl-1,4-naphthoquinone PR-99 2, 5-bis(dimethylamino)-1,4-benzoquinone PR-100 2,5- dimethyl-3,6-bis(dimethylamino)-1,4-benzoquinone PR-lOl 2,5-dimethyl-3,6-bispyrrolidino-1,4-benzoquinone PR-102 2-ethoxy-5-methyl-1,4-benzoquinone PR-103 2 ,6-dimethoxy-1,4-benzoquinone PR- 104 2~5-dimethoxy-1,4-benzoquinone PR- 105 2,6-diethoxy-1,4-benzoquinone PR-106 2,5-diethoxy-1,4-benzoquinone PR-107 2,5-bis~2-methoxyethoxy)-1,4-benzoquinone .
PR-108 2,5-bis~-phenoxyethoxy)-1,4- : :
benzoquinone : ,, .
PR-109 2,5-diphenethoxy-1,4-benzoquinone PR-llO 2,5-di-n-propoxy-1,4-benzoquinone PR-lll 2,5-di-isopropoxy-1,4-benzoquinone PR-112 2,5-di-n-butoxy-1,4-benzoquinone PR-113 2,5-di-sec-butoxy-1,4-benzoquinone PR-Il4 1,1'-bis(5-methyl-1,4-benzoquinone-2-yl)-dlethyl ether 0 PR-115 2-methyl-5-morpholinomethyl-1,4-3 benzoquinone PR-116 2,3,5-trimethyl-6-morpholinomethyl-1,4 benzoquinone PR-117 2,5-bis(morphol momethyl)-1,4-benzocluinone :PR- 118 2-hydroxymethyl-3,5,6-trimethyl-1,4-benzoquinone PR-ll9 2-(1-hydroxyethyl)-5-methyl-1,4-benzoquinone PR-120 2-(1-hydroxy-n-propyl)-5-methyl-1,4-~ benzoquinone : .,. ::' . ' .. -2~-.

7~
TABLE IV Cont.
Exemplary Internal Hydrogen Source Quinones PR-121 2~ h~droxy-2-methyl-n-propyl)-5-methyl-1,4-benzoquinone PR-122 2-~1,1- dimethyl-2-hydroxyethyl) -5-methyl-1,4-benzoquinone PR-123 2-~].-acetoxyethyl)-5-methyl-1,4-benzoquinone PR-124 2-(1-methoxyethyl)-5-methyl-1,4-benzoquinone PR-125 2-(2-hydroxyethyl)-3,5,6-trimethyl-1,4-benzoquinone PR-126 2-~thoxy-5-phenyl-1,4-benzoquinone PR-127 2-i-propoxy-5-phenyl-1,4-benzoquinone PR-128 1,4-dihydro-1,4-dimethyl-9,10-anthra-quinone PR-129 2-dimethylamino-1,4-naphthoquinone PR-130 2-methoxy-1,4-naphthoquinone PR-131 2-benzyloxy-1,4-naphthoquinone PR-132 2-methoxy-3-chloro-1,4-naphthoquinone PR-133 2,3-dimethoxy-1,4-naphthoquinone PR-134 2 ,3-diethoxy-1,4-naphthoquinone PR-135 2-ethoxy-1,4-naphthoquinone PR-136 2 -phenethoxy-1,4-naphthoquinone PR-137 2- (2-methoxyethoxy)-1,4-naphthoquinone PR-138 2- (2-ethoxyethoxy)-1,4-naphthoquinone PR-139 2-(2-phenoxy)ethoxy-1,4-naphthoquinone : PR~140 2-ethoxy-5-methoxy-1,4-naphthoquinone PR-141 2-ethoxy-6-methoxy-1,4-naphthoquinone -25- :

~ 5~ ~0 ~
TABLE IV Gont.
Exemplary Internal Hydrogen Source ~uinones PR-142 2-ethoxy-7-methoxy-1,4-naphthoquinone PR-143 2-n-propoxy-1,4-naphthoquinone PR-144 2-(3-hydroxypropoxy)-1,4-naphthoquinone PR-145 2-isopropoxy-1,4-naphthoquinone PR-146 7-methoxy-2-isopropoxy-1,4-naphthoquinone PR-147 2-n-butoxy-1,4-naphthoquinone PR-148 2-sec-butoxy-1,4-naphthoquinone PR-149 2-n-pentoxy-1,4-naphthoquinone PR-150 2-n-hexoxy-1,4-naphthoquinone ~ .
PR-151 2-n-heptoxy-1,4-naphthoquinone PR-152 2-acetoxymethyl-3-methyl-1,4-naphtho- -quinone - PR-153 2-methoxymethyl-3-methyl-1,4-naphthoquinone PR-154 2-~-acetoxyethyl)-1,4-naphthoquinone PR-155 2-N,N-bis~cyanomethyl)aminomethyl-3-methyl-1,4-naphthoquinone PR-156 2-methyl-3-morpholinomethyl-1,4-naphthoquinone PR-157 2-hydroxymethyl-1,4-naphthoquinone PR-158 2-hydroxymethyl-3-methyl-1,4-naphthoquinone PR-159 2-(1-hydroxyethyl)-1,4-naphthoquinone PR-160 2-(2-hydroxyethyl)-1,4-naphthoquinone PR-161 2-(1,1-dimethyl-2-hydroxyethyl)- .
1,4-naphthoquinone : .
PR- 162 2-bromo-3-isopropoxy-1,4-naphthoquinone 3 PR- 163 2-ethoxy-3-methyl-114-naphthoquinone ~ PR- 164~2-chloro-3-plperidino-1,4-naphthoquinone :~ PR- 165 2-morpholino-1,4-naphthoquinone ~ :
PR-~166 2,3-dipiperidino-1,4-naphthoquinone .

~5~ 6 T~BLE IV Cont.
Exemplary Internal Hydro~en Source Quinones P~ 167 2-dibenzylamino-3-chloro-l,L~-naphthoquinone PR-168 2-methyloxycarbonylmethoxy-1,4-naphthoquinone PR-169 2-(N-e~hyl-N-benzylamino)-3-chloro-1,4-naphthoquinone PR-170 2-morpholino-3-chloro-1,4-naphthoquinone PR-171 2-pyrrolidino-3-chloro 1,4-naphtho-quinone PR-172 2-diethylamino-3-chloro-1,4-naphtho-quinone PR-173 2-diethylamino-l,L~-naphthoquinone PR ~174 2-piperidino-1,4-naphthoquinone PR-175 2-pyrrolidino-1,4-naphthoquinone PR-176 2-(2-hexyloxy)-1,4-naphthoquinone PR-177 2-neo-pentyloxy-1,4-naphthoquinone - PR-178 2-(2-n-pentyloxy)-1,4-naphthoquinone PR-179 2-(3-methyl-n-butoxy)-1,4-naphtho-quinone PR-180 2-(6-hydroxy-n-hexoxy)-1~4-naphtho-quinone PR-181 2-ethoxy-3-chloro 1~4-naphthoquinone PR-182 2-di(phenyl)methoxy-1,4-naphthoquinone PR-183 2-(2-hydroxyethoxy)-3-chloro-1,4-naphthoquinone PR-184 2-methyl-3-(1-hydroxymethyl)ethyl-1,4-naphthoquinone :~
PR-185 2-aze~idino-3-chloro-1~4-naphthoquinone .... .
PR-186 2-(2-hydroxyethyl)-3-bromo-1,4-naphtho-quinone PR-187 2,3-dimorpholino-1,4-naphthoquinone : - PR-188 2-ethylamino-3-piperidino-1,4-naphtho-quinone PR-189 2-ethoxymethyl-1,4-naphthoquinone PR-l90 2-phenoxymethyl-1,4-naphthoquinone : -27-, , . - . , . ~ . . ~ . .... ~ .. - . . .

~51~7~6 - While each of the various categories of photo-reductants noted above form a redox couple with cobalt(III)-complexes upon exposure to actinic radiation in excess o~
300 nanometers in wavelength, the photoreductants vary some-what in the manner and mechanism through which they react.
Many of the photoreductants react rapidly with the cobalt-(III)complex upon exposure to actinic radiation. Certain of the quinone photoreductants exhibit this reaction characteristic. Other of the photoreductants form a redox couple upon exposure, but require an extended period to reduce the cobalt(III)complex. In most~ instances it is desirable to heat the redox couple formed by the exposed photoreductant and cobalt(III)complex to drive the r-eaction to a more timely completion. Although optimum levels of heating vary considerably, depending upon specific choices of photoreductants, cobalt(III)complexes, other materials present and desired photographic speeds, typically, heating the redox couple in the temperature range of from 80 to 150C is preferred.
Photoreductant Adiuvants The photoreductants employed in the practice of this invention shif-t the position of or change the number of atoms contained within the molecule in the course of conversion to the corresponding reducing agent. Internal hydrogen source quinones are exemplary of photoreductants capable of relying entirely on the atoms initially present ~ithin the molecule to permlt conversion to the corresponding reducing agent.
In other photoreductants conversion to the corresponding reducing agent may require that an adjuvant be present in intimate association ~ith the photoreductant to donate the necessary atoms to perm1t formation of the reducing agent.

. ~. ,':. .

~ 5~ 6For example, in quinones lacking an internal hydrogen source it is necessary to employ in combination an adjuvant capable of functioning as an external source of hydrogen atoms. In most instances we have observed significant impro~ements in performance by employing in combination with our photo-reductants an adjuvant, such as an external hydrogen source, to facilitate conversion of the photoreductant to a reducing agent, whether or not the photoreduetant itself contains the requisite atoms for its conversion to a reducing agent.
Any conventional source of labile hydrogen atoms that is not otherwise reactive with the remaining components or their reaction produets eontained within the photographic element can be utilized as an adjuvant. Generally preferred for use are organie compounds ha~ing a hydrogen atom attached to a carbon atom to which a substituent is also attached which greatly weakens the carbon to hydrogen bond, thereby rendering the hydrogen atom labile. Preferred hydrogen souree compounds are those which have a hydrogen atom bonded to a carbon atom to which is also bonded the oxygen atom of an oxy substituent and/or the trivalent nitrogen atom of an amine substituent.
As employed herein the term "amine substituent" is inclusive of amide and imine substituents. Exemplary preferred substituents which produee marked lability in a hydrogen atom associated with a common carbon atom are oxy substituents, such ` - as hydroxy, alkoxy, aryloxy, alkaryloxy and aralkoxy substituents and amino substituen-ts, sueh as alkylarylamino, diarylamino~ amido, N,N-bis(1-cyanoalkyl)amino, N-aryl-N-tl-cyanoalkyl)amino,N-alkyl-N~ eyanoalkyl)amino, N,N-bis-(l-earbalkoxyalkyl)amino, N-aryl-N-(l-earbalkoxyalkyl)amino, N-alkyl-N-(l-earbalkoxyalkyl)amino, N-N-bis(l-nitroalkyl)-amino~ N-alkyl-N (l-nitroalkyl)amino, N-aryl-N-(l-nitroalkyl)-~05~7~
amino, N,N-bis(1-acylalkyl)amino, N-alkyl-N~ acylalkyl)-amino, N-aryl-N(1-acylalkyl)amino, and the like. The aryl substitllents and substituent moieties are preferably phenyl or phenylene while the aliphatic hydrocarbon substituents and substituent moieties pre~erably incorporate twenty or ~ewer carbon atoms and, most pre~erably, six or fewer carbon atoms.
~xemplary of compounds which can be used in the practice of this invention for the purpose of providing a ready source of labile hydrogen atoms are those set forth in Table V.
Compounds known to be useful in providing labile hydrogen atoms are also disclosed in U.S. Patent 3,383,212, issued May 14, 1~68.

.- : - , :. . , :

~5~6 TABLE V.
Exemplary External Hydrogen Source Compounds HS- 1 poly(ethylene glycol) HS- 2 phenyl-1,2-ethanediol HS- 3 nitrilotriacetonitrile HS- 4 triethylnitrilotriacetate HS- 5 poly(ethylene glycol) HS- 6 poly(vinyl butyral) HS- 7 poly(vinyl acetal) HS- 8 1,4-benzenedimethanol HS- 9 methyl cellulose HS-10 cellulose acetate butyrate HS-ll 2,2-bis-(hydroxymethyl)-propionic acid HS-12 1,3-bis-(hydroxymethyl)-urea HS-13 4-nitrobenzyl alcohol HS-14 4-methoxybenzyl alcohol HS-15 2,4-dimethoxybenzyl alcohol HS-16 3,4-dichlorophenylglycol HS-17 N-(hydroxymethyl)-benzamide HS-18 N-(hydroxymethyl)-phthalimide HS-I9 5-(hydroxymethyl)-uracil hemihydrate HS-20 nitrilotriacetic acid HS-21 Z,2',2"-triethylnitrilotripropionate .
HS-22 2,2'~2"-nitrilotriacetophenone HS-23 poly(vinyl acetate) HS-24 poly~vInyI alcohol) HS-25 ethyl cellulose . HS-26 carboxymethyl cellulose HS-27 poly(vInyl formal) ~L~5~7~6 The external hydrogen source adjuvants incorporated within the photographic elements of the present invention can, in fact, perform more than one function. For example, the polymers included in Table V can also be used as binders as well as to provide a source of labile hydrogen atoms. These compounds are designated as external hydrogen source compounds only to point up that the labile hydrogen atoms are not incorporated in the photoreductant.
Radiation-Sensitive Composition, La~er and Element To form a radiation-sensitive composition useful in the present invention it is merely necessary to bring together the photoreductant and the cobalt(III)complex. If required by the choice of photoreductant, an adjuvant should also be included. The radiation-sensitive composition can then be . ~.
brought into a spacially fixed relationship, as by coating the composition onto a support to form a radiation-sensitive element according to the present invention. For maximum efficiency of performance it is preferred that the components of the radiation-sensitive composition, particularly, the -photoreductant, the cobalt(III)complex and the adJuvant, if any, be intimately associated. This can be readily achieved, for example, by dissolving the reactants in a solvent system.
The solvent system can be a common solvent or a combination of miscible solvents which together bring all of the reactants into solution. Typical preferred solvents which can be used alone or in combination are lower alkanols, such as methanol, ethanol, isopropanol, t-butanol and the like;
~- ketones, such as methylethyl ketone, acetone and the like, water, liquid hydrocarbons; chlorinated hydrocarbons, such as chloroform, ethylene chloride, carbon tetrachloride and the llke; ethers, such as diethyl ether, tetrahydrofur&n, and ~ 3 ~5~7~6 the like; acetonitrile; dimethyl sul~oxide and dime-thyl formamide.
For ease of coating and ~or the purposes of impart-ing strength and resilience to the radiation-sensitive layer it is generally preferred to disperse the reactants in a resinous polymer matrix or binder. A wide variety of natural and synthetic polymers can be used as binders In order to be useful it is only necessary that the binders be chemically compatible with the reactants. In addition to performing their ~unction as a binder the polymers can also serve as adjuvants such as external hydrogen sources to supplement or replace other adjuvants such as hydrogen sources as described above. For example, any of the polymers set ~orth in Table V can be used both as binders and as external hydrogen sources.
It is preferred to employ linear ~ilm-~orming polymers such as, for example, gelating cellulose compounds, such as ethyl cellulose, butyl cellulose, cellulose acetate, cellulose triacetate, cellulose butyrate, cellulose acetate butyrate and the like; vinyl polymers~ such as poly(vinyl acetate), poly(vinylidene chloride), a poly(vinyl acetal) such as poly(vinyl butyral), poly(vinyl chloride-co-vinyl acetate), polystyrene, and polymers o~ alkyl acrylates and methacrylates including copolymers incorporating acrylic or methacrylic acid; and polyesters, such as poly(ethylene glycol-co-iso-phthalic acid-co-terephthalic acid), poly(~-cyclohexane dicarboxylic acid-co-isophthalic acid-co-cyclohexylenebis-methanol~), poly(~-cyclohexanedicarboxylic acid-co-2,2,4,4-tetramethylcyclobutane-1,3-diol) and the like. The condensation product o~ epichlorohydrin and bisphenol is also a~pre~erred useful binder. Generally any binder kno~n 33~

:~

~ 6~53L7~6 to have utility in photographic elements and, particularly, diazo photographic elements can be used in the practice of this invention. These binders are well known to those skilled in the art so tha-t no useful purpose would be served by including an extensive catalogue of representative binders in this specification. Any of the vehicles disclosed in Product Licensing Index Vol. 92, December 1971, publication 9232, at page 108, can be used as binders in the radiation-sensitive elements of this invention.
While the proportions of the reactants forming the radiation-sensitive layer can be varied widely, it is generally preferred for most efficient utiliza-tion of the reactants that they be present in roughly stoichiometric concentrations--that is, equal molar concentrations. One or more of the reactants can, of course~ be present in excess. For example, where the external hydrogen source is also used as a binder, it is typically present in a much greater concentration than is essential merely for donation of labile hydrogen atoms.
It is generally preferred to incorporate from 0.1 to 10 moles of the cobalt(III)complex per mole of the photoreductant.
Adjuvants, such as external hydrogen sources, supplied solely to perform this function are typically conv~niently incorpor-ated in concentrations of from 0.5 to 10 moles per mole of photoreductant. The binder can account for up to 99~ by weight of the radiation-sensitive layer, but is typically employed ln proportions of from 50 to 90~ by ~eight of the radiation~sensitive layer. It is, of course, xecognized that the b m der can be omitted entirely from -the radiation-sensitive ` layer. The surface or areal densities of the reactants can vary, depending upon the specific application; however, it is generally preferred to incorporate the cobalt(III)complex . . .

3L6~5~ )6 in a concentration of at least l x 10 7 moles per s~uare decimeter and, most preferably, in a concentration of from 1 x 10 5 to 1 x 10 ~ moles per square decimeter. The areal densities of the remaining reactants are, of course, proportionate. Typically~ the radiation-sensitive layer can vary widely in thickness depending on the characteristics desired for the radiation-sensitive element~-e.g., image density, flexibility, transparency, etc. For most photo-graphic applications coating thic~nesses in the range of from 2 microns to 20 microns are preferred.
Any conventional photographic support can be used in the practice of this invention. Typical supports include transparent supports, such as film supports and glass supports as well as opaque supports, such as metal and photographic paper supports. The support can be either rigid or flexible.
Preferred supports for most applications are paper or film supports. The support can incorporate one or more subbing layers for the purpose of altering its surface properties.
Typically subbing layers are employed to enhance the adherency of the radiation-sensitive coating to the support. Suitable exemplary supports are disclosed in Product Licensing Index Vol. 92, December 1971, publication 9232 at page 108.
The radiation-sensitive layer can be formed on the support using any conventional coating techni~ue. Typically the reactants, the binder (if employed) and any other desired addenda are dissolved in a solvent system and coated onto the support by such means as whirler coating, brushing~ doctor blade coating, hopper coating and the like. Thereafter the solvent is evaporated. Other exemplary coating procedures are set forth in the Product icensing Index publication cited above, at page 109. Coating aids can be incorporated 1~5~L7~

into the coating composition to facili-tate coating as dis-closed on page 108 of the Product Licensing Index publication.
It is also possible to incorporate antistatic layers and/or matting agents as disclosed on this page of the Product Licensing Index publication.
As is illustrated in Fig. 1, in a simple ~orm the radiation-sensitive element 100 can be formed entirely of a support 102 and a radiation-sensitive layer 10~. In -this form the radiation-sensitive element need not exhibit an image-recording capability, rather the radiation-sensitive element merely exhibits a selective response to imagewise exposure with actinic radiation. The selective response can be usefully employed, as in recording the image in a separate photographic element. In a preferred radiation-sensitive element of this type the cobalt(III)complex incorporates one or more ligands which can be volatilized upon reduction o~ the complex. For example, the cobalt(III)-complex can incorporate one or more ammine ligands which are liberated as ammonia upon imagewise reduction of the cobalt-(III)complex. For such an application it is preferrea tochoose a cobalt(III)complex which incorporates a large number of ammine ligands, as are present in cobalt hexa-ammine and cobaIt penta-ammine complexes.
Separate Image-Recording Layers and Elements Where the radiation-sensitive layers employed in the practice of this invention do not incorporate an image-recording capability, it is contemplated that a separate image-recording layer be used with the radiation-sensitive layer. In a simple form a separate image-recording element can be used in combination with a radiation-sensitive element, s~ch as element 100. In this way reaction products released upon -36_ . , .

.~ . . ...
- . . .

imagewise ex~osure o~ the radi~tion-sensitive ele~ent can be transferred in an image pattern to produce an image printout or bleachout in the image-recording layer. In one form of the invention it is contemplated that ammonia will be image-wise transferred ~rom the radiation-sensitive layer to a separate image-recording element. In such instance the image-recording element can take the ~orm of any conventional element containing a layer capable of producing an image as a result o~
ammonia receipt org more generally, contact with a base.
In a simple ~orm the image-recording element can con~
sist o~ a support bearing thereon a coating including a material capable o~ either printout or bleachout upon contact with ammonia. For example, materials such as phthalaldehyde and ninhydrin printout upon contact with ammonia and are there-fore use~ul in ~orming negative images. A number o~ dyes, such as certain types of cyanine dyes, styryl dyes, rhodamine dyes, azo dyes, etc. are known capable o~ being altered in color upon contact with a base. Particularly pre-ferred ~or ~orming positive images are dyes which are bleached by contact with a base, such as ammonia, to a substantially transparent ~orm. Pyrylium dyes have been ~ound to be parti-cularly suited ~or such applications. While the image-recording layer can consist essentially o~ a pH or ammonia responsive imaging material, in most instances it is desirable to include a binder ~or the imaging material. The image-recording element can be formed using the same support and binder materials employed in ~orming the radiation-sensitive elemen-t or in any other convenient, conventional manner.
To record an image using separate radiation-sensitive and image-recording elements, the radiation-sensitive layer o~

~[35~7~&~

the radiation-sensitive element is first imagewise exposed to radiation of from 300 to about 900 nm, preferably to radiation o~ from 300 to 700 nm. This can be accomplished using a mercury arc lamp, carbon arc lamp, photoflood lamp, laser or the like. Upon exposure to actinic radiation the photoreductant present in the radiation~sensitive layer is converted to a reducing agent in exposed areas and ~orms a redox couple with the cobalt(III)complex. Where a redox couple is formed tha-t reacts rapidly at ambient temperatures, it is desirable to have the image-recording layer of the image-recording element closely associated with the radiation~sensitive layer at the time o~
exposure. Where the redox couple reacts more slowly, as in those instances where it is desirable to drive the redox reaction to completion with the application of heat, the image-recording element can be associated with the radiation-sensitive element before or after exposure. ~or example, in one form the radiation-sensitive element can be exposed and thereafter associated with the image-recording element, as by feeding the elements with the radiation-sensitive and image-recording 2Q layers juxtaposed between heated rolls. After the radiation-sensitive element has been used to produce an image in the image-recording element, it can be discarded or, where a more slowly reaoting redox couple is formed, reused with another image-reGording element to provide another photographic print.
Where a oobalt(III)complex is employed which contains ammine ligands, it is contemplated that the ammonia given off upon reduotion of the complex can, by proper ohoice of reactants~
stimulate ~urther imagewise release of ammine ligands. ~or ~x~mple, ~4-superoxodecammine dioobalt(III) oompounds oan be -38_ ~C35~7~6 decomposed by contact with free ammonia. Hence, when a - radiation-sensitive layer is formed using this type of cobalt-(III)complex, the reaction of the photoreductant, which has been converted to a reducing agent by irradiation, and the ammine ligand containing cobalt(III)complex initiates reduction of the complex, but thereafter the ammonia released can further reduce the f~-superoxodecammine dicobalt(III) compound in irradiated areas.
In a~other form of this invention a hydrogen amine (e.g., ammonia or a primary or secondary amine) can be employed in place of radiation to convert a quinone to a reducing agent for a cobalt(III)complex. For example, where a quinone is provided which is unsubstituted in at least one quinoid ring position adjacent a carbonyl group (e.g., a 2 or 3 ring position in the case of l,L~-benzoquinones and l,~-naphthoquinones), a hydrogen amine such as ammonia can react with the quinone at the unsubstituted ring position to form the corresponding amino-1,4-hydroquinone. The hydroquinone then reduces the cobalt(III)complex. Where the cobalt(III)complex contains a releasable hydrogen amine ligand, still more hydroquinone will be generated. The reaction can be initiated by any source of hydrogen amine. The quinone can function initially as a photo-reductant or a ~separate photoreductant can be incorporated lnitially to reduce a hydrogen amine containing cobalt(III)-complex and liberate the hydrogen amine. In another form the hydrogen amine can be externally supplied. In still a~other form the reduction of a cobalt(III)complex to liberate hydrogen amine can be directly stimulated with ultraviolet light or by sensitizing the cobalt(III)complex to visible light.
The practice of this invention employing separate radiation-sensitive and image-recording elements is illustrated by reference to the following examples:

~ 5~7~
Examples 1 through 20 An image~recording element was in each instance formed by adding a solution of 30 mg of dye, identified below in Table VI, in 0.50 grams of dimethylformamide to 5.0 grams of a 10 percent by weight solution of cellulose acetate butyrate in acetone. The resulting solution was coated at 43C on a poly(eth~lene terephthalate) film support to a wet coating thickness of approximately 100 microns and dried.
A radiation-sensitive element was formed b~ solvent coating onto a poly(ethylene terephthalate) film support a composition 8.1 mg/dm2 of 2-isopropoxy-1,4-naphthoquinone (PR-145), 6.2 mg/dm2 of cobalt hexa-ammine acetate (C-l) and 60.3 mg/dm2 of cellulose acetate butyrate (HS-10) in acetone. -The radiation-sensitive element was given a 20 second imagewise exposure with an ultraviolet light source available under the trademark 'IKalfile Printer 340 VC" from Canon. The exposed radiation-sensitive coating and the image-recording coating were placed face-to-face and passed through a pair of pressure rollers heated to 100C-and having a linear speed of o.66 cm/secO After passing between the rollers, the radiation-sensitive and image-recording elements were separated and the image-recording la~er viewed. The observed results are set forth below in Table VI~

:
~$a '' ~S~7~

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O ~ ~1 ~ ~ ~1 ~1 ~1 ~1 ~:1 C~~~ o O o o o C~ o o o C) C~ C) ~ C) O

?
p;
a~
~ ~ ~ " O :~
~ o C~ ~ ~
h o 3 ~ ~ o ~ P ~1 M h ~ o ~ h o ,Q bO ,O :-H ~1 0 . .
. ' :
~1 rl ~ h P I c~ ~ I ~ ~1 o _ c~ ~ r I ~ O h ~ I ~ ' E~ ~ rll h o ~ h I ,~
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~ 53L7~6 Example 21 The procedure of Examples 1 through 20 was repeated substituting 4-(4-diethylaminostyryl)quinoline monohydro-chloride as the dye present. The unexposed area was red and the exposed area was bright yellow.
Example 22 .
The procedure of Examples 1 through 20 was repeated substituting for the dye 30 mg of 3',6'-bis(N-methyl~N-phenyl-amino)fluoran and 13 mg of p-toluenesulfonic acid (to yield a rhodamine dye of the type disclosed in British Patent 1,286,885). The unexposed area was dark violet and the exposed area was light violet.
Example 23 A radiation-sensitive element was formed by coating a mixture of 0.2 gram of PR-145; 0.1 gram of C-l; 0.5 gram HS-10; 5.0 grams of 2-methoxyethanol and 5.0 grams of acetone to a wet coating thickness of approximately 100 microns on a poly(ethylene terephthalate) film support, An image-recording element was formed by coating a mixture of 8.o grams of 10 percent cellulose acetate butyrate~
in ~0:20 weight ratio acetone/methyl alcohol solvent system;
0.25 g of o-phthalaldehyde and 1.75~grams acetone on a poly-(ethylene terephthalate) ~ilm support to a wet coating thick-ness of approximately 100 microns.
After drying the radiation-sensitive coating was imagewise exposed ~or 0.5 second using a L~oo watt medium pressure mercury arc lamp available under the trademark "Micro Master Diazo Copier Model 2D" from I~M
providing light primaril~ in the , : ' . ' .
~ ,', ' ~S~7~6 300 to 500 nm wavelength range. The image-recording and exposed radiation-sensitive layers were then placed in face-to-face abutment and passed between a pair of rollers heated to 100C. Upon separating the radiation-sensitive element, the image-recording element exhibited a neutral image having a density of l.0 to l.5. The image-recording element was substantially free of background printout and no printout in background areas was observed during subse~uent handling o~
the image~recording element in room light.
Example 24 A composition was prepared consisting essentially of 130 mg of 4-diethylaminobenzenediazonium tetrafluoroborate (PR-29); 1500 mg of C-3; 30.1~ grams of 2-methoxyethanol; and ; 68~0 grams o~ 10% by weight solution of HS-lO in a 80:20 mixture of acetone and methyl alcohol. me composition was coated on a poly(ethylene terephthalate) ~ilm support to a wet coating thickness of lO0 microns and allowed to dry.
The dried coating was imagewise exposed for 2 seconds using as a radiation source a medium pressure mercury lamp providing radiation principally in the range o~ from 300 to 500 nanometers. The radiation-sensitive element was then placed in face-to-face relationship with an ammonia bleachable image-recording element. The image~recording element was rormed by coating a solution consisting essentially of 3.96 grams 2,4-diphenyl-6-(beta-methyl-3,4-diethoxystyryl) pyryIium tetrafluoroborate; 19.~0 grams of cellulose acetate butyrate;
- and 273.~0 grams acetone~ to a wet coating thickness of lO0 microns on a poly(ethylene terephthalate) film support. me ~ two elements were passed between rolls heated to l30CC in ; 30 face-to-face relationship. The dye was bleached in areas " .

~L~35::3L7(1 6 corresponding to the radiation-exposed areas of the radiation-sensitive element to produce a positive magenta image.
Examples 25 through 32 The procedure o~ the preceding example was repeated, but with the substitution o~ various diazonium salts as photo-reductants. me photoreductants and results are set forth below in Table VII. An exposure of 4 seconds was employed.

TABLE VII

Example Image No. Photoreductant . Qualit~
(PR-L~7) weak 26 (PR-52) good 27 (PR-53) good 28 (PR-56) weak 29 (PR-59) moderately wea~
(PR-62) weak 31 (PR-65) moderately weak 32 (PR-6~) moderately weak A ~urther illustrative practice o~ this invention employing separate radiation-sensitive and image-recording ele-ments can be appreciated by re~erence to Figures 2 through 4 o~
the drawings. In ~igure 2 the radiation-sensitive element 100 comprised o~ support 102~ which in this instance is a substantially transparent support, and radiation-sensitive layer 104 is placed in contact with an article 106 to be copied comprised o~ support lOo and coated image areas llOa, llOb~
3 llOc and llOd. me~support is ~ormed to provide a re~lective sur~ace. ~or example~ the support can be paper or can be ~ormed with a re~lective coating. The image areas are formed using a material which is substantially absorptive within the spectrum ~ 5~7~)6 of exposure.
With the elements 100 and 106 associated as illustrated the radiation-sensitive element is uniformly exposed to actinic radiation, indicated schematicall~ by arrows 111~, through the support 102. Substantially all of the radiation reaches and penetrates the radiation-sensitive layer 104. A significant portion of the radiation reaches the article to be copied and is either absorbed or reflected back into the radiation-sensitive layer, depending upon whether the radiation impinges upon the reflective surface 112 or the image areas. As a result of differential availability of actinic radiation to the radiation-sensitive layer, exposed zones 116 are formed in the radiation-sensitive layer in which a comparatively high concentration of redox couple is formed.
After exposure the radiation-sensitive element is separated from the article to be eopied and is brought into contact with an image-recording element 118 comprised of a support 120 and an image-recording layer 122~ In the form shown the image-recording is chosen to be initially colored, but capable of being bleached, although an initially colorless image-recording layer that is capable of being colored could be alternatively employed. Upon the uniform application of heat, as is schematically illustrated by the arrows 124, the redox couples formed in the exposed areas 116 of the radiation-sensitive layer are caused to react. The reaction product diffuses from the radiation-sensitive la~er 104 to the adjacent image-recording layer 122 and causes the image-recording layer to become bleached in areas 126a, 126b, 126c and 126d. Thus, a positive copy of the article 106 is formed.
By employing an initially colorless image recording layer that is colored by receipt of reaction products from the radiation-sensitive layer a negative copy of ~5~
the article can be formed. It is thus apparent that either positive or negative copies can be formed by reflex exposure techni~ues according to the practice of this invention. It is, of course, recognized that the practice of this invention is not limited to reflex exposure techniques, although these are advantageous for many applications.
Reflex exposure is further illustrated by reference to the following example:
Example 33 The following solution was prepared: Cobalt(III) hexa-ammine acetate (C-l) 115 mg, 2-morpholino-1,4-naphtho-quinone (PR-165) 80 mg, cellulose acetate butyrate (HS-10) lg, and acetone 10 ml.
The above solution was coated to 100 microns wet thickness on a poly(ethylene terephthalate) support. After drying, a black-on-white document was then placed face down onto the above coating. A reflex exposure was carried out by exposing through the support of the photosensitive intermediate to a 650 watt incandescent la~p available under the trademark "120 Multi Spectrum Copier" from Nashua, for 3 seconds. The document was removed and the exposed intermediate was heated in contact with an ammonia sensitive receiver sheet at 100-110C for 10 seconds by passing the composite through a pair of heated rolls. The receiver sheet was coated with an acidified solution of 3,3'-dimethylene-2,2'-spirobi[(2H)naphtho-~2,156]pyran] in ~IS-10. A blue-on-white positive copy of the black-on-white document was obtained. When a conventional diazo recording element (commercially available under the tradename RECORDA~ Diazo-M) was used, as a receiver sheet, a negative copy of the document was obtained.
.

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L7~6 Instead of employing separate radiation-sensitive and image-recording elements, separate radiation-sensitive and image-recording layers can be incorporated within a si.ngle element. This can be illustrated by re~erence to Figure 5.
An element 200 is schematically sho~n comprised of a support 202 and a radiation-sensitive layer 20L~, which can be identical to support 102 and radiation-sensitive layer 104, described above. Overlying the radiation sensitive layer is a separation layer 206. An image-recording layer 20~, which can be identical to the separate image-recording layers pre-viously discussed, overlies the separation layer. I~ desired, the relationship o~ the image-recording and radiation-sensitive la~ers can be interchanged.
Ihe separation layer is an optional component of the element 200, since în most instances the image-recording and radiation-sensitive layers are chemically compatible for substan-tial time periods. However, to minimize any degradation of properties of either of the active layers due to migration of chemical components from one layer to the other, as could conceivably occur during extended periods of storage before use, it is preferred to incorporate the separation layer.
qlhe separatio~ layer is chosen to be readily permeable by the reaction product(s) to be released -~rom the radiation-sensitive layer upon exposure while impeding unwanted migration of initially present components of the radiation-sensitive and image-recording layers. For example, the separation layer can be chosen to be readily permeable to a~monia, but relatively impermeable to liquid components. It has been found that a 3 wide range o~ polymeric layers will permit diffusion o~ gaseous : ammonia from the radiation-sensitive layer to the image-recording layer while otherwise inhibiting interaction o~ the components : of these layers.
. 48 -- ....... ..... . .

~5~1L7~6 It is generally pre~erred to employ hydrophobic polymer layers as separation layers where the radiation-sensitive and image-recording layers incorporate polar reactants whose migration is thought to be inhibited. ~ost pre~erred are linear hydrocarbon polymers, such as polyethylene, polypropylene, polystyrene and the like. It is generally pre~erred that the separation layer exhibit a thickness o~ less than about 200 microns in order to allow image definition to be retained in the image-recording layer. For most applications ~eparation layers o~ 20 or ~ewer microns are pre~erred.
Photoresponsive Separate_Ima~e-Recor_ing Layersc~ Elements While the separate image-recording layers heretofore described need not themselves be radiation responsive, image-recording layers wbich are responsive both to reaction products released by the radiation-sensitive layers and also directly responsive to actinic radiation are recognized to be useful in the practice o~ this invention. ~or example, a conventional diazo recording element can be used as an image-recording element in the practice o~ this invention. Typically diazo recording elements are ~irst imagewise exposed to ultraviole-t light to in- -activate radiation-struck areas and then uni~ormly contacted with ammonia to printout a positive image. Diazo recording elements can initially incorporate both a diazonium salt and an ammonia activated coupler (commonly re~erred to as two-component :
diazo systems) or can initially incorporate only the diazonium salt and rely upon subsequent prooessing to imbibe the coupler (commonly re~erred to as one-component diazo systems). Both one component and two component diazo systems can be employed in the~practioe o~ this lnvention. Subsequent discussions, although directed to the more common two component diazo systems, should be recognized to be applicable to both systems. The photo-' _~9~
. ~ ;

~ L~5~7C~6 responsive image-recording layers can be incorporated in separate image-~ecording elements or can be incorporated directly within the radiation-sensiti~e elements o~ this invention, such as illustrated in Figure 5.
The use of a radiation-sensitive layer and a separate photoresponsive image-recording layer in combination offers a versatility in imaging capabilities use~ul in forming either pos itive or negative images. The production of a positive image with such a combination can be readily appreciated by reference to Figure 6. In this figure a radiation-sensitive layer 302 and a photoresponsive image-recording layer 3O~such as a con~en-tional diazo recording layer, are associated in face-to-face relationship. The layers together with a support and separation layer can, i-f desired, form a single element, such as element 200, or, in the alternative, the separate layers can be provided by placing a conventional diazo recording element and the radiation-sensitive element 100 in -face-to-face relationship.
As employed herein the term "face-to-face relationship" means simply that the image-recording and radiation-sensitive layers are adjacent and not separated by a support, as would occur in a back-to-back relationship.
To -form a positive image the photosensitive image-recor~lng layer 304 is first imagewise exposed to ultraviolet radiation, as is schematically indicated by transparency 306 bearing the image 308. This photolytically destroys the diazonium salt in the exposed areas of the image-recording layer. The radiation-sensitive layer 302 is preferably uniformly exposed to actinic radiation before it is associated with the layer 304, where separate image-recording and radiation-sensitive elements are 3 employed. Alternately, where a single element is employed incor-porating~ayers 302 and 304, the radiation-sensitive layer is . . .
-5~-~5~7~6 uniformly exposed using radiation in the visible spectrum so as not to destroy the diazonium salt in image areas. Exposures through either major outer surface are contemplated where the layers 302 and 304 form a single element. Transparent or opaque supports can be used with either single or plural element arrangements. Heating of the layers 302 and 304 in face-to-face relationship results in ammonia being released from the radiation-sensitive layer for migration to the diazo layer, thereby activating the coupler in the diazo layer to prod~ce a dye image 310, which is a positive copy of the image 308. If an element bearing a negative image is substituted for transparency 306, the negative image will be reproduced in the layer 304.
The identical photosensitive image-recording and separate radiation-sensitive layer combination employed to form a positive image in Figure 6 can also be used to -form a negative image, as illustrated in Figure 7. To form a negative image the radiation-sensitive layer is first imagewise exposed, as indicated by the transparency 306 bearing the image 308. Where the layers 302 and 304 are in separate elements the radiation-sensitive element zo is preferably exposed before association with the image-recording element. Where the layers are in a single element, the radiation-sensitive layer is preferably exposed with visible radiation to avoid deactivating the diazo layer. ~ith the layers associated as shown, they are uniformly heated. This imagewise releases ammonia from the radiation-sensitive layer which migrates to the diazo layer, causing imagewise print~ut. The area of the diazo layer defining the negative image 312 can then be deactlvated by ':
exposure to ultraviolet light, if desired, although this is not required. The image 312 is a negative copy of the image 308. If 3U an element bearing a negative image is substituted for transparency 306, the image will be reversed in the layer 304.
... . .

:: ,, .. . . .. . .

~S~7~6 Numerous variations are contemplated and will be readily apparent to those skilled in the art. For e~ample, the photoreductant and photoresponsive image-recording layer can be variously chosen to be responsive to other portions o~
the spectrum. Instead of the photoreductant being responsive to visible light and the diazo layer being responsive to ultra-violet light, as noted above, a diazonium salt can be chosen which is selectively responsive to visible light and a photo-reductant chosen that is selectively responsive to either visible or ultraviolet light. Where both the radiation-sensitive and photoresponsive image-recording layers are present in a single element and are responsive to the same portion of the spectrum~ it is necessary to provide a trans-parent support and it is desirable to include a separation layer that is substantially opaque to that portion of the spectrum. It is also contemplated that for certain applications the separation layer can advantageously be formed of or include an ultraviolet absorbing material. In still another variation, where uniform ammonia release is employed to develop the diazo image, a supplementary base treatment can be used to enhance the diazo image if desired.
The practice of this invention employing a photo~
responsive image-recording layer and a separate radiation-sensitive layer in combination is further illustrated by the following examples:
Examples 34 through 15~ ~
~ In each instance a coating composition was prepared consisting essentially of 1.0 gram of cellulose acetate butyrate (HS-10); 11.3 grams ethylene dichloride, 2.0 grams methanol; 2 : 3 drops of water; 0.10 gram hexa-ammine cobalt~III) acetate (C-l) and 1.00 millimole of a photoreductant. E.ach coating composition : -52-: . : -,.

-: : i ~, - - . : . : . :

~LCl 5~ 6 was used to prepare two identical coatings on poly(ethylene terephthalate) film support each having a wet coating thickness of approximately 100 microns. Where it was desired to expose a coating to an additional light source an additional, identical pair of radiation-sensitive elements was prepared.
~ xposure was undertaken using either a predominantly ultra-violet and blue light source or a predominantly visible light source. The ultra-violet and blue light source employed a 400-watt medium pressure mercury arc lamp. A 2-second exposure was given with this light source. This light source is commercially available under the trade name Micro Master Diazo Copier. The predominantly visible light source employed an incandescent lamp of 650 watts, and a 16-second exposure was given using this light source. This light source is commercially available under the trade name Nashua 120 Multi-Spectrum Copier. In each instance exposure was made through a 0.3 log E silver step tablet. Approx~
imately 10 seconds after exposure the radiation-sensitive element was placed in face-to-face relationship with a diazo recording .. . .. . .,, .. . . . ................ _ _ _ _, element commercially available under the trademark RECORDAK
? Diazo M Film. To produce a negative image in the diazo-recording element the face-to-face elements were Passed three times between rollers heated to 100 C at a linear rate of o.66 cm/sec.
~ The speed of the radiation-sensitive elements was calculated as the quotient of 100 divlded by the time in seconds required to reach ~eutral image density above gross fog of 0.40.
For purposes of comparison those elements exhibiting speeds below 12.5 were considered to be slow; those exhibiting speeds of from 12.5 to 50 were categorized as moderately slow; those exhibiting speeds of from 50 to l00 were considered moderately fast; and those exhibitin~g speeds above 100 were categorized as being fast. The averaged results with each identically prepared and exposed pair of radiation-sensitive elements are reported below in Table VIII, -53- :

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1--1 ~ v ~cl c~ ~I rl ~1 0 X O
H ~ O ~ ,~
H ~ .S P~ ~ ~ O ~ ~ ~ ~ u~
P., u~ ~ ~ O W O ~t ~ O ~ ~ t O
h ~ ~ ~ ~ ¢ U r~
~ t~ U hH ~ 1_l bc t~ ~ bO r-l bD
P ~ 1~l rl ~ ~ ~
¢ p~ h C) O O O ~ F O ~ r-l o-rl ~-rl X .5: ~ F ~ Y X '~
rl~ h O ~ h ~rl u~ p, ~ q t~ O ~ t~ r~ S
u u ~ u ~
t~ ~ I h O F~ u o O
~ ~ a~ o ~1 h C~
O U oo O~ l O ~ C) rl r~ d ~ ul ~ U U
o ~ I I s~ ¢ ~ ~
C) ~ ~ O 0, ~d ~rl ~ U) ~ ~ ~ S~ ~ ' O ~ ~ ~d O h ~ , z o ~ o ~:4 t) o ~ a) ,,, ~ ,~
~, ~ Z h a~ ~ ~d O r~
: r~ r~ O U O
~--1 O O O ~ O oo 1~ ~ P-l ~ rl ,: , ~ 5 Ei O N ~ ¢ ~
X u) Il') O O ' ~ ~ ~) d- ~ ' ~ ~I V V z z ~

: .: ~ :

., , . . ... .~.,.. ., , .. .. ~ . .. . . .. . . . .... .

7~tii Example 154 Example 34 was repeated, but with the use of photo-reductant PR-27, a 4-second exposure to the ultraviolet and blue light source, and a 2-pass development at 130 C. A diazo print was produced having a "slow" rating as defined in Example 34.
~xamples 155 and 156 Example 148 was repeated, but with the substitution of photoreductants PR-9 and 24, respectively. Similar results were obtained in each instance.
Example 157 A radiation-sensitive element was prepared as described in Example 23. The radiation-sensitive element was placed in face-to-face relationship with a diazo rccording element having a transparent base (commercially available under .. . . . . . . ......................... . . .. ..
the trade~ark KODAK Diazo Type ~ Fil~). The exp~suré and develop-ment procedure of Example 23 was repeated resulting in a reversed copy of the original image. The diazo recording layer was then fixed against further printout by uniform exposure to ultraviolet light.
Example 158 A radiation-sensitive element and diazo recording element identical to those of the preceding example were mounted in face-to-face relationship. The combined elements were first imagewise exposed through the diazo recording element for 2 seconds using the exposure unit of Example 23. Thereafter the combined elements were flash exposed for 0.5 second through the radiation-sensitive element using the same exposure unit and developed as in Example 23. An image was formed in the diazo recording element which was a positive of the image copied.

., , ~

1(~5~6 Examples 159 through 162 A composition was prepared consisting essentially of 130 mg of PR-29; 1500 mg of C-3; 30.4 grams of 2-methoxyethanol;
and 68.0 grams of 10% by weight solution of HS-10 in a 80:20 mixture of acetone and methyl alcohol. The composition was coated on a poly(ethylene terephthalate) film support to a wet coating thickness of 100 microns and allowed to dry. The dried coating was imagewise exposed for 8 seconds using as a radiation source a medium pressure mercury lamp providing radiation principally in the range of from 300 to 500 nanometers. The radiation-sensitive element was then placed in face-to-face relationship with a diazo recording element having a transparent base (commercially available under the trademark KODAK Diazo Type M Film), and the two elements so related were passed between rolls heated to 130 C.
A negative of the original image was formed in the image-recording element which was ~ixed by subse~uent exposure of the image-recording element to room light.
:' The procedure of the preceding example was repeated,but with the substitution of various diazonium salts as photo-reductants. The photoreductants and results are set forth below in Table IX.
TABLE IX
Example No. Photoreductant Image Quality 159 PR-Z9 good 160 PR-32 weak 161 PR-35 good 162 PR-41 good :
~ Example 163 . .
~ A coating composition was prepared by dissolving 0.2 gram of~C-l in 9 grams of 10~ by we~ight poly(vinyl alcohol) in : .,, : ~
... .
~: :

.: ,: .,: :; ., . ;, : : . . , . ~ .

~S~7~6 water. To this was added a solution of 0.2 gram of PR-160 in 1 gram of n-propanol. The composition was coated to a wet thickness of approximately 100 microns on a poly(ethylene tere-phthalate) film support. The dried coating was imagewise exposed to an ultraviolet and blue radiation source medium pressure mercury arc lamp for 8 seconds. This light source is commercially available under thetrademark Micro Master Diazo Copier. The radiation-sensitive element was placed in face-to-face relationship with a diazo recording element having a transparent base (commercially available under the trademark KODAK Diazo Type M
Film). The radiation-sensitive element and the image-recording element in face-to-face abutment were then passed between a pair of rollers hea~ed to 100 C at a linear rate of advance of 0.68 centimeter/sec. A negative diazo image was formed.
xamples 164 through 165 The procedure of the preceding example was repeated in each instance with C-6~ C-13, and C-16 substituted for C-l.
In each instance a negative diazo image was obtained in the image-recording element.
20 Example _ 6 Following the procedure of Example 163, except as otherwise stllated,two coatings were prepared. Both coatings differed from the radiation-sensitive coating of Example 158 in sub-stituting 0.115 gram of C-5 for the 0.2 gram of C-l. One of the coatlngs further differed from the coating of Example 163 through the omission of the photoreductant. The coating lacking a photo-reductant produced no image even though it was exposed for 32 seconds. The remaining coating produced a negative image in the diazo-recording element having a neutral density of 0.7.
Example 167 ~ Following the procedure of Example 163, except as otherwise stated, 0.2 gram of C-20 was substituted for G-l. The : `~

:' ~
.~:
... _ __ ._. ~ . .. .... .. _ .. ___ . . . .. _ .. ..... _ ~

~5~7~6 coating lacking a photoreductant produced no image in the diazo-recording element while the coating containing PR-160 ~roduced a negative image in the diazo-recording elemen~ having a neutral density of 0.7.
Example 168 Following the procedure of Example 163, except as otherwise stated~ 0.37 gram of C-16 was substituted for 0.2 gram of C-l. After exposure of 4 seconds a negative image was obtained in the diazo-recording element having a neutral density of 0.45, Example 169 Following the procedure of Example 163, except as otherwise stated, 0.2 gram of C-31 was substituted for C-l. After an exposure of 2 seconds a negative image was obtained in the diazo-recording element having a neutral density o-f 1.0, Example 170 - An element 200 was formed using 100 micron poly-~ethylene terephthalate) to form the support 202. A radiation-sensitive layer 204 having a wet coating thickness of approximately 75 microns was ormed on the support using a coating composition consisting essentially of 0.2 gram PR-145; 0,1 gram C-l; 0.5 gram HS-10; 5.0 grams 2-methoxy ethanol and 5.0 grams acetone. After drying, a separation layer 206 was formed on the photosensitive image-recording layer using as a coating composition 10.0 grams of toluene and 0.5 gram styrene-butadiene copolymer. The separation exhibited a wet coating thickness of approximately 50 microns, Again, after drying~ a photosensitive image-recording layer 208 was formed on the support to a wet coating thickness of approximately 100 microns from a composition consisting of 0.02 gram 5-sulphosalicylic acid; 0.066 gram _-~diethylamino)benzene-:
diazonium tetrafluoroborate; 0,084 gram naphthol AS-D coupler (commercially available from GAF Corporation) and 0.8 gram cellulose acetate butyrate, A positive image was made by imagewise exposing the element from the diazo side for 7 seconds using a high pressure mercury vapor light source commercially available under the trademark 3M Filmsort Uniprinter Copier. The element was then given a 3-second uniform exposure with the same light source through the support. The element was then heated for 5 seconds, support down, on a heat block maintained at 115 C. I~ positive image was obtained. The element exhibited a maximum neutral image density of 1.1 and a neutral minimum background density of 0.07.
Example 171 The preceding example was repeated, except that a negative image was formed by first imagewise exposing for 3 seconds through the support followed by heating. The residual diazonium salt was destroyed with an overall exposure of 7 seconds from the diazo layer side. Background and image densities wer- identical to those of the p~eceding example.

.

.

~S~ 6 Radiation-Sensitive Layers with Image-Recording Capabilities In employing a radiation-sensitive layer to also perform the function of image-recording, a radiation-sensitive element, such as element 100, can be employed having a radiation-sensitive layer containing only a cobalt(III)complex and a photoreductant as active components. To record images with a radiation-sensitive element of this type the cobalt(III)complex is employed as an oxidant for a leuco dye which is convertible to a colored form upon oxidation.
Alternatively, conventional dye-forming components (e.g., an oxidizable organic color developer and a coupler) can be employed which are converted to a coloreddye upon oxidation o~ the organic color developer and coupling. In this approach the radiation-sensitive layer is initially imagewise exposed to form a redox couple in radiation-struck areas and thereafter heated to insure that the cobalt(IIIlcomplex is reduced to a cobalt(II) compound in these areas. Thereafter, the radiation-sensitive layer is brought into contact with a leuco dye or the dye-forming com-ponents are brought together within the radiation-sensitive layer.
The cobalt~III)complex remaining in the non-irradiated areas then oxidizes the leuco dye or the organic color developer so that a colored image is formed in the non-irradiated areas of the radiation-sensitive layer. The organic color developer and coupler therefor can be introduced into the radiation-sensitive layer together or separately. As is well understood in the art, both the coupler and the oxidizable organic color developer can be contained in the developer solution and concurrently introduced into the radiation-sensitive layer. In a preferred form a ballasted ~- ~ coupler is employed which is initially contained within the rad]ation-sensitive layer with the organic color developer being later introduced. A wide variety of conventional techniques for .~
ntroducing the dye-lmage-forming components into the radiation-~sensitlve layer can be used ranging from bathing the radiation-.. . . . ... . . . ~ . . .,. , . , ~ . . . ~ . . . . .

~S~L7~
sensitive element, after exposure and heating, in dye-~orming component solutions to re]easing the dye-formin~ components from pressure rupturable containers such as pods or micro-encapsulation layers contained in the radiation-sensitive element or a separate element abutted therewith.
A wide variety of oxidiz~ble leuco dyes and oxidizable,dye-forming component c~mbinations are ~nown to the art that can be readily emplo~ed in the practice of this invention. Exemplary leuco dyes include amlnotriarylmethane~ aminoxanthenes,aminothioxanthen~s, amino-9,lO~dihydroacridines, aminohydrocinnamic acids (cyanoethanes), aminodiphenylmethanes, aminohydrocinnamic acids (cyanoethanes), leucoindigoid dyes, 1,4-diamino-2,3-dihydroanthraquinones, etc.
In addition to these general categories of useful leuco dyes there are numerous other types of amines which can be oxidized to a colored species, such as those set forth in U.S. Patents 3,042,515 and 3,042,517--e.g., 4,4'-ethylenedianiline, diphenylamine, N,N~
dimethylaniline, 4,4'-methylenedianiline, triphenylamine, N-vinyl-carbazole, and the like. Certain hydrazones and acyl derivatives of these hydrazones can be oxidized to diazonium compounds which will then couple with any of a large number of coupling agents to produce an azo dye. Exemplary compounds of this type are disclosed in U.S. Patent 3,076,721, here incorporated by reference. Exemplary of couplers useful with such hydrazones and acyl derivatives thereof are N,N-diethylaniline, N,N-dimethyl-m-toluidine and N-(2-cyanoethyl)-N-methyl-2-naphthylamine. Aromatic diamines in com-bination with a coupling agent can produce upon oxidiation azo-methlne and lndoaniline dyes. Exemplary of N,N-dialkylphenylene-diamines, which are preferred for use in the practice of this - - .
invention~ are N,N-dimethyl-~-phenylenediamine and N,N-dimethyl-toluene-2,5-dlamine;. These amines are useful with couplers such as 2-acetyl-4'-chloroacetanilide, 2-benzoyl-2'-methoxyacetanilide, - -o-ethylphenol, 2-naphthol, 7-acetylamino-1-naphthol, N,N-dimethyl-anlllne and N,N-diethyl-m-toluldine. Further specific illustrations ~ L~5~706 of oxidizable leuco dyes and dye-forming component combinations useful in the practice of this invention are provided in U.S.
Patent 3,383,212, here incorporated by reference.
Instead of utilizing the residual cobalt~III)complex remaining after exposure and heating to form an imaging coloration, it is recognized that the reaction products formed on imaging and/or heating can be employed to form an image within the radiation-sensitive layer, if desired. This approach has the advantage of requiring no additional processing. Any compound can be incor-porated which is compatible with the remaining components of the radiation-sensitive layer and which is capable of either being bleached or darkened upon contact with or further reaction with one or more o-f the reaction products formed on imaging and/or heating. In one form such a component can be identical to one of the components previously described for incorporation in a separate image-recording layer. For example~ a component such as ninhydrin or o-phthalaldehyde can be incorporated which generates a color upon contact with ammonia released as a reaction product upon imaging and/or heating of the radiation-sensitive layer.
Alternatively, bleachable dyes, such as the pyrylium, styryl, cyanine, rhodamine and similar conventional dyes lcnown to exhibit color alterations upon contact with a base can be incorporated into the radiation-sensitive layer.
A cobalt(~II) compound produced as a reaction product in the course or reducing a cobalt(III)compl~x in the radiation sensitive layer can, if desired, be used to record images. To be useful ln forming an image within the radiation-sensitive layer it is merely necessary that any cobalt(II) compound formed in exposed areas be visibly distinguishable from the original cobalt-3~ (III)complex present in unexposed areas. Typically cobalt(II)compounds produced as reaction products tend to be subs~an~ially ~ -66-~ .

~53L7~i colorless so that they are best suited to forming image back-grounds. By choosing a cobalt(III)complex of a distinctly differ-ing hue which is reducible to a substantially colorless cobalt-(II) compound, useful positive images can be formed within the radiation-sensitive layer. In the preferred form of the inven-tion both the cobalt(III)complex as well as the photoreductant and the oxidation products thereof are substantially colorless.
Cobalt(II) compounds can then be imagewise generated which form readily discernible, optically dense images by selecting a compound for inclusion in the radiation-sensitive layer which is compatible with the remaining components of the radiatlon-sensitive layer and which is capable of forming a visi~le colored cobalt(II)complex as a ligand thereof. We have discovered that it is possible to produce optically dense cobalt(II) compounds useful in forming negative images by incorporating into the radiation-sensitive layer a compound capable of chelating with the cobalt(II) atom formed on reduction of the cobalt(III)complex.
In the pre~erred practice of this invention the chelating coIn-pound is initially present with and chemically compatible with the cobalt(III)complex and the photoreductant within the radiation-sensitive layer.
While a variety of compounds are known to be capable of forming optically dense chelates with cobalt(II) atoms and ;
can~be employed in the practice of this invention, preferred .: . . , chelating compounds include formazan dyes, dithiooxamides, nitroso-arols~ azo compounds, hydrazones, and Schiff bases. As is well understood by those skilled in the art all formazan dyes are capable of forming bidentate chelates and are therefore use-ful in the practice of this invention. Preferred formazan dyes are those having a ring-bonded, aromatic substitutent in the 1 .
and 5 positions. In formazan dyes it is unnecessary that either -67_ ~Cl 5~7~6 of these aromatic substituents exhibit a ligand-forming capability in order for the dye to exhibit a bidentate chelate-forming capability, but chelate ligand-forming, aromatic substituents can be chosen~ if desired, to produce additional chelate ligands. Dithiooxamide is a preferred chelating compound as well as derivatives thereof having one or both nitrogen atoms substituted with an alkyl, alkaryl, aryl, or aralkyl group. Preferred nitroso-arol compounds are those in which the nitroso and hydroxy substituents are adjacent ring position substituents (e.g., 2-nitrosophenols, l-nitroso-2-naphthols, 2-nitroso-1-naphthols, etc.). Preferred azo compounds capable of forming at least bidentate chelates with cobalt(II) are those of the general formula.:~

Z -N=N-Z .

Preferred hydrazones capable of forming at least bidentate chelates with cobalt(II) are those of the general formula:

Z3-CH-N-NH-Z4~

Preferred Schiff bases capable of forming at least bidentate chelates with cobalt(II) are those of the general formula:

Z5-CH=N-Z6.

20 : ~In the foregoing formulas each of the Z substituents are chosen to be ring-bonded, aromatic substituents and at least z2, z3, z4, Z5 and z6 are chosen to be capabIe of ~ormlng a chelate ligand. The aromatic substituents of the ligand-forming compounds can take the form of either homocyclic or heterocycllc single- or~multiple-ring substitutents, such as phenyl, naphthyI, anthryl, pyridyl, quinolinyl, azolyl, etcO

-. ~ .
~ ~ ~ -68-i ~ g~5~7a~
In one form the aromatic substituent can exhibit a ligand forming capability as a result of being substituted in the ring position adjacent the bonding position with a substituent which is sus-ceptible to forming a ligand, such as a hydroxy, carboxy or amino group. In another form the aromatic substituent can be chosen to be an N-heterocyclic aromatic substituent which contains a ring nitrogen atom adjacent the azo bonding position--e.g., a 2-pyridyl, 2-quinolinyl, or 2-azolyl (e.g. 2-thiazolyl, 2-benzothiazolyl, 2-oxazolyl, 2-benzoxazolyl, etc.) substituent. The aromatic sub-stituents can, of course, bear substituents which do not interferewith chelating, such as lower alkyl (i.e., one to six carbon atoms), benzyl, styryl, phenyl, biphenyl, naphthyl, alkoxy (e.g., methoxy, ethoxy, etc.), aryloxy ~e.g., phenoxy), carboalkoxy (e.g., carbo-methoxy, carboethoxy, etc.), carboaryloxy (e.g., carbophenoxy, ~-carbonaphthoxy), acyloxy (e.g., acetoxy? benzoxy, etc.), acyl (e.g., acetyl, benzoyl, etc.), halogen (i.e., fl~loride, chloride, bromide, iodide), cyano, azido, nitro, haloalkyl (e.g., trifluoromethyl, trifluoroethyl, etc.), amino (e.g., dimethylamino), amido (e.g., acetamido, benzamido)~ ammonium (e.g., trimethylammonium)~ azo (e.g., phenylazo), sulfonyl (e.g., methylsulfonyl, phenylsulfonyl), sulfoxy ., ~ . .... . .
(e.g., methylsulfoxy), sulfonium (e.g., dimethyl sulfonium), silyl ~e.g., trimethylsilyl) and thioether (e.g., methylthin) substituents.
It is generally preferred that the alkyl substituents and substituent moieties have 20 or Eewer carbon atoms, most preferably six or fewer carbon atoms. The aryl substituents and substituent moieties are preferably phenyl or naphthyl groups. Exemplary preferred chelate-forming compounds are set forth in Table X.

-69_ ~: , . .

~L~517~
TABLE X
Exemplary Chelate-For_ing _ompounds CH- 1 1,3,5-triphenylformazan CH- 2 1-(4-chlorophenyl)-3,5-diphenylformazan CH- 3 1-(4-iodophenyl)-3,5-~diphenylformazan CH- 4 1,5-diphenylformazan CH~ 5 1,5-diphenyl-3-methylformazan CH- 6 1,5-diphenyl-3-(3-iodophenyl)formazan CH- 7 1,5-(2-carboxyphenyl)-3-cyanoformazan CH- 8 1,5-diphenyl-3-acetylformazan CH- 9 1,3-diphenyl-5-(4-diphenyl)formazan CH-10 1-(2-hydroxyphenyl)-3,5-diphenylformazan CH-ll 1-(2-carboxyphenyl)-3,5-diphenylformazan CH-12 1-phenyl-3-~3~4-dimethoxyphenyl)-5-(4-nitrophenyl)formazan : CH-13 1~5-diphenyl-3-(2-naphthyl)formazan CH-14 1-phenyl-3-undecyl-5-(4-nitrophenyl)-formazan CH-15 1-(2-hydroxy-5-sulfophenyl)-3-phenyl-5-(2-carboxyphenyl)formazan CH-16 1,5-diphenyl-3-carbohexoxyformazan CH-17 1-~4-methylthiophenyl~-3-(3-nitrophenyl)-5-~3,5-dichlorophenyl)~ormazan CH-18 1-(2-naphthyl) 3-(4-cyanophenyl)-5-(3~
nitro-5-chlorphenyl)formazan CH-l9 1-(3-pyridyl)-3-(4-chlorophenyl)-5-phenylformazan ~, .
CH-20 1-(2~4~5-trichlorophenyl)-3-phenyl-5-(4-nitrophenyl)~ormazan ;~: CH-21 1-(4-pYridyl3-3-phenyl-5-(2~trifluOrO_ methylphenyl ~ormazan CH-22 ~ 1-(2-nitro-4-chlorophenyl)-3-(4-chloro-phenyl-5-(4-phenylazophenyl)~ormazan ~
CH-23~ 1,3-diphenyl-5-(2-pyridyl)formazan ~.
CH 24 ~1-(2,5-dimethylphenyl)-3-phenyl-5-(2-pyridyl)formazan : .

~:
~ _70_ ~
'" ' :
.

~S~L7~6 TABLE X Cont.
Exemplar~_Chelate-Formin~ Compounds CH-25 1-(2-pyridyl)-3-(4-cyanophenyl)-5-(2-tolyl)formazan CH-26 1-(2-benzothiazolyl)-3-phenyl-5-(2-pyridyl)~ormazan CH-27 1-(4,5-dimethylthiazol-3-yl)-3-(4-bromophenyl)-5-(3-tri~luoromethyl-phenyl)formazan --CH-28 1~3-diphenyl-5~(benzothiazol-2-yl)-formazan CH~29 1-(benzoxazol-2-yl)-3~phenyl~5-(4-chlorophenyl)~ormazan CH-30 1,3-diphenyl-5-(2-quinolinyl)~ormazan CH-31 1-phenylazo-2-phenol CH-32 1-phenylazo-4-dimethylamino-2-phenol CH-33 2-hydropheny-lazo-2-phenol CH-34 1-(2-hydroxyphenylazo)-2-naphthol CH-35 1-(2-pyridylazo)-2-naphthol CH-36 1-(2-pyridylazo)-2-phenol CH-37 1-(2-pyridylazo)-4-resorcinol CH-38 1-(2-quinolylazo)-2-naphthol CH-39 1-(2-thiazolylazo)-2-naphthol CH-40 1-(2-benzothiazolylazo)-2-naphthol CH-41 1-(4-nitro-2-thiazolylazo)-2-naphthol ~; CH-42 1-(2-thiazolylazo)-4-resorcinol CH-43 2,2-azodiphenol : CH-44 1-(3,4-dinitro-2-hydroxyphenylazo)-2~5-phenylene-diamine ; CH-45 1-(2-benzothiazolylazo)-2-naphthol. . .
CH-46 1-(1-isoquinolylazo)-2-naphthol . .
: CH-47 2-pyridinecarboxaldehyde-2-pyridyl- : :
hydrazone ~: ~ CH-48 2-pyridinecarboxaldehyde-2-benzothia-: - zolylhydrazone ' 5~6 TABLE X Cont.
Exemplar~y~ te-Forming Compounds CH-49 2-thiazolecarboxalclehyde-2-benzoxa-zolylhydrazone CH-50 2-pyridi.necarboxaldehyde-2-quinolyl-hydrazcne CH-51 1-(2-pyridinecarboxal.dehyde-imino)-2-naphthol CH-52 1-(2-quinolinecarboxaldehyde-imino)-2-naphthol CH-53 1-(2-thiazolecarboxaldehyde-imino)-2-naphthol CH-54 1-(2-benzoxazolcarboxaldehyde-i.mino)-2-phenol CH-55 1-(2-pyridine carboxaldehyde-imino)-2-phenol CH-56 1-(2-pyridinecarboxaldehyde-imino)-2-pyridine 20- CH-57 -(2-pyridinecarboxaldehyde-imino)-2-CH-58 1-(4-nitro-2-pyridinecarboxaldehyde-imino)-2-thiazole CH-59 1-(2-benoxazolecarboxaldehyde-imino)-2-- oxazole CH~60 1-nitroso-2-naphthol CH-61 2-nitroso-1-naphthol CH-62 1-nitroso-3,6~disul~o-2~naphthol CH-63 disodium 1-nitroso-2-naphthol-3,6-di-- sul~onate 30 ~ CH-64 4-nitrosoresorcinol GH-65 2-nitroso-4-methoxyphenol CH-66 dithiooxamide CH-67 N,N'~dimethyldithiooxamide .
- CH-68 N,N'-diphenyldithiooxamide ;
CH-69 N,N'-di-n-hexyldithiooxamide CH-70 N,N'-di-~-tolyldithiooxamide :

~5~
In still another form of this invention inorganic metal sulfide images can be formed within the radiation-sensitive layer. This can be achieved b~ incorporating into the radiation-sensitive layer in combination with the cobalt(III)-complex and the photoreductant compounds such as those contain-ing one or more thioamide functional groups--e.g.g thiourea, thioacetamide and substituted and/or cyclized derivatives thereof. It has also been discovered that the use o~ a trans-parent overlayer incorporating one or more thioamide compounds will increase the optical density of images obtained. The overlayer offers the further advantage that it allows greater concentrations of the thioamides to be employed. It has also been observed that superior results are obtained using thio-amides to produce images if the radiation-sensitive layer is heated concurrently with exposure. It is recognized that the use o~ a cobalt(III)complex and a photoreductant in combination can be used to enhance the radiation sensitivity and spectral response of radiation-sensitive systems sueh as those disclosed in UOS. Patents 1~897,843; 1,962,307; and 2,084~420~ cited above.
All of the compounds added to the radiation-sensitive layer can be introduced similarly as the leuco dye or oxidizable dye-forming component combina-tions. That is, these image-forming compounds can be added to the radiation~sensitive layer by conventional procedures a~ter imagewise exposure, if desired. To minimize processing it is generally preferred to incorporate the image-forming compounds capable of reacting with the reaction products formed on exposure directly into the radiation-sensitive layer at the time it is ~ormed. This -30 can be conveniently accomplished by dissolving the image-forming compound within the coating composition used to form the radiation-sensitive layer. While the proportions of-the image-forming compounds incorporated within the ~,'~ .

~(3 5~'7~t~

radiation-sensitive layer can be widely varied, it is generally preferred that the image-forming compound be present in a concen-tration of from 0.1 to 10 parts per part by weight of cobalt~III)-complex initially present in the radiation-sensitive layer. It is speci-fi.cally recognized that the radiation-sensitive layers and elements having image-forming capabilities can be employed in combination with image-recording layers and elements similarly as those radiation-sensitive layers and elements lacking image recording capabilities.
The practice of the invention is further illustrated by reference to the following examples:
Example 172 A coating composition was prepared consisting essentially of 0.3 gram ninhydrin; 0.2 gram 2-isopropoxy-1,4-naphthoquinone ~PR-145); 0.1 gram hexa-ammine cobalt~III) acetate ~C-l); 0.1 gram water; 6 grams 2-methoxy ethanol; 4 grams acetone; and 0.4 gram cellulose acetate butyrate ~HS-10). The coating composition was spread to a wet thickness of approximately 100 microns on a poly-~ethylene terephthalate) film support and allowed to dry. The dried coating was exposed imagewise to a high pressure mercury lamp as a radiation-source. A faint brown negative image was formed whlch greatly intensified upon heating to 115C. for 5 to 10 seconds.
Example 173 .
The procedure of the preceding Example was repeated, but o-phthalaldeh~de was substituted for ninh~drin. Upon heat-ing a black negative image was formed.

Example 174 ~',.
The procedure of the preceding Example was repeated, ., 3Q but with the substi~tution of a coating composition consisting essentlally of 0.2 gram 2-isopropoxy-l~4-naphthoquinone ~PR-145);
7~

.

~L~5~6 0.66 gram ~-superoxodecammine dicobaltate(III) perchlorate (C-20);
0.75 gram cellulose acetate butyrate (HS-10) and lO.0 grams dimethyl formamide. After exposure and heating as in the preceding Example the radiation-sensitive element was immersed in a solution of leuco malachite green in toluene. A green positive image was formed.
Example 175 .
A coating composition was prepared consisting essentially of C-3, 500 mg; C~1-43, 65.0 mg; PR-1~5, 220 mg; ~IS-10, 1000 mg;
and 10 mg acetone. A coating was formed USillg the comp~sition having a wet thickness of 100 microns on a poly(ethylene terephthalate~
film support. After drying the coating was imagewise exposed to an ultraviolet and blue radiaton source medium pressure mercury arc lamp for 0.5 second. This light source is commercially available under the trademark Micro Master Diazo Copier. The imagewise exposed coating was then heated to 100C. for 10 seconds by passage between heated rollers. A b,ri~ht red,,ima~ w~s formed in irradiated areas havi~g a densit~ o~ 1.3.
Example 176 A coating composition was prepared consisting essentially of C-15, 210.0 milligrams; CH-35, 120 milligrams; PR-145, 110.0 mg;
HS-lO, 1000.0 mg; and 10 mg acetone. The procedure of the pre-ceding Example was repeated, except that the coating was imagewise exposed for 8 seconds. A magenta image was formed in exposed areas having a density of 1.3.
Example 177 , ..
A composition was prepared consisting essenti'ally of 20 , mg. 4-diethylamino-ben~enediazonium tetrafluoroborate PR-29; 100 mg., C-3; and o-phthalaldehyde in 10 grams of methyl alcohol. The composition was imbibed in a filter paper and after drying was imagewise~exposed for 2 seconds using as a radiation source a medium pressure mercury lamp. This radiation source is commercially . ~ .

. . .. ~.

~ 5~7~)6 available under the trademark Micro Master Diazo Copier. The exposed coating was then heated for approximately 5 seconds at 110 C. A black image was formed in irradiated areas.
Example 178 Following the procedure of Example 163, except as other-wise stated, 0.23 gram of C-2 was substituted for 0.2 gram of C-l.
A diazo recording element having a transparent base was used of a type commercially available under the trademark KOD~K Diazo Type H Film. A negative image was formed in the diazo receiver sheet and a blue negative image was formed in the radiation-sensitive layer.
The invention has been described in detail with parti-cular 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.

:, :

Claims (56)

We Claim:

1. A radiation-sensitive element comprising (A) a support and, (B) as a coating, a radiation-sensitive layer comprised of 1) a cobalt(III)complex free of a sensitizable anion and 2) a photoreductant capable of forming a redox couple with the cobalt(III)complex upon exposure to actinic radiation longer than 300 nanometers in wavelength.

2. A radiation-sensitive element according to claim 1 in which said cobalt(III)complex is not directly reducible by exposure to electromagnetic radiation of a wavelength longer than 300 nanometers.

3. A radiation-sensitive element according to claim 1 in which said cobalt(III)complex contains ammine ligands.

4. A radiation-sensitive element according to claim 3 in which said cobalt(III)complex contains at least five ammine ligands.

5. A radiation-sensitive element according to claim 4 in which said cobalt(III)complex contains a hexa-ammine cobalt(III) cationic moiety.

6. A radiation-sensitive element according to claim 4 in which said cobalt(III)complex contains a µ -superoxodeca-amine dicobalt(III) cationic moiety.

7. A radiation-sensitive element according to claim 1 in which said cobalt(III)complex contains an anionic moiety exhibiting a pKa of greater than 3.5.

8. A radiation-sensitive element according to claim 7 in which said anionic moiety is a thiocyanate.

9. A radiation-sensitive element according to claim 7 in which said anionic moiety is a carboxylate.

10. A radiation-sensitive element according to claim 1 in which said photoreductant is a quinone, disulfide, diazo-anthrone, diazophenanthrone, aromatic carbazide, aromatic azide, diazonium salt, diazosulfonate or mixture of two or more of these photoreductants.

11. A radiation-sensitive element according to claim 1 in which said photoreductant is a 10-diazoanthrone.

12. A radiation-sensitive element according to claim 10 additionally including an adjuvant for reduction of the photo-reductant.

13. A radiation-sensitive element according to claim 1 additionally including means for supplying a source of labile hydrogen atoms.

14. A radiation-sensitive element according to claim 13 in which said photoreductant is a quinone.

15. A radiation-sensitive element according to claim 14 in which said quinone is a 1,4-benzoquinone, a 1,4-naphthoquinone, a 1,2-naphthoquinone, a 9,10-phenanthrenequinone, or a 9,10-an-thraquinone.

16. A radiation-sensitive element according to claim 14 in which said photoreductant is chosen from the group consisting of 9,10-phenanthrenequinone, 2-(1-formyl-2-propyl)-1,4-benzoqui-none and 2-methyl-1,4-benzoquinone.

17. A radiation-sensitive element according to claim 1 in which said photoreductant incorporates one or more labile hydrogen atoms.

18. A radiation-sensitive element according to claim 17 in which said photoreductant is a quinone.

19. A radiation-sensitive element according to claim 18 in which said labile hydrogen atoms are attached to a carbon atom which is also bonded to the oxygen atom of an oxy substituent or the nitrogen atom of an amine substituent with the further provision that the carbon to hydrogen bond is the third or fourth bond removed from at least one quinone carbonyl bond.

20. A radiation-sensitive element according to claim 19 in which said quinone is a 1,4-benzoquinone or 1,4-naphthoquinone and incorporates as 2 or 3 position substituents at least one substituent chosen from the class consisting of 1' or 2'-hydroxyalkyl, hydroxyalkoxy, alkoxy, 1' or 2'-alkoxyalkyl, aralkoxy, 1' or 2'-acyloxyalkyl, 1' or 2'-aryloxyalkyl, aryloxy-alkoxy, 1' or 2'-aminoalkyl, 1' or 2'-aroyloxyalkyl, alkylaryl-amino, dialkylamino, N,N-bis(1-cyanoalkyl)amino, N-aryl-N-(1-cyanoalkyl)amino, N-alkyl-N-(1-cyanoalkyl)amino, N,N-bis (1-carbalkoxyalkyl)amino, N-aryl-N-(1-carbalkoxyalkyl)amino, N-alkyl-N-(1-carbalkoxyalkyl)amino, N,N-bis(1-nitroalkyl)amino, N-alkyl-N-(1-nitroalkyl)amino, N-aryl-N-(1-nitroalkyl)amino, N,N-bis(1-acylalkyl)amino, N-alkyl-N-(1-acylalkyl)amino, N-aryl-N-(1-acylalkyl)amino, pyrrolino, pyrrolidino, piperidino and morpholino substituents.

21. A radiation-sensitive element according to claim in which said quinone is chosen from the group consisting of (a) 1,4-naphthoquinone (b) 9,10-phenanthrenequinone (c) 2-ethoxy-5-methyl-1,4-benzoquinone (d) 2,6-diethoxy-1,4-benzoquinone (e) 2,5-diethoxy-1,4- benzoquinone (f) 2,5-bis(2-methoxyethoxy)-1,4-benzoquinone (g) 2-ethoxy-5-phenyl-1,4-benzoquinone (h) 2-i-propoxy-5-phenyl-1,4-benzoquinone (i) 2-methoxy-1,4-naphthoquinone (j) 2-benzyloxy-1,4-naphthoquinone (k) 2-ethoxy-1,4-naphthoquinone (l) 2-phenethoxy-1,4-naphthoquinone (m) 2-(2-methoxyethoxy)-1,4-naphthoquinone (n) 2-(2-ethoxyethoxy)-1,4-naphthoquinone (o) 2-(2-phenoxy)ethoxy-1,4-naphthoquinone (p) 2-ethoxy-5-methoxy-1,4-naphthoquinone (q) 2-ethoxy-6-methoxy-1,4-naphthoquinone (r) 2-ethoxy-7-methoxy-1,4-naphthoquinone (s) 2-n-propoxy-1,4-naphthoquinone (t) 2-(3-hydroxypropoxy)-1,4-naphthoquinone (u) 2-isopropoxy-1,4-naphthoquinone (v) 7-methoxy-2-isopropoxy-1,4-naphthoquinone (w) 2-n-butoxy-1,4-naphthoquinone (x) 2-sec-butoxy-1,4-napbthoquinone (y) 2-n-pentoxy-1,4-naphthoquinone (z) 2-n-hexoxy-1,4-naphthoquinone (aa) 2-n-heptoxy-1,4-naphthoquinone (bb) 2-hydroxymethyl-1,4-naphthoquinone (cc) 2-hydroxymethyl-3-methyl-1,4-naphthoquinone (dd) 2-(1-hydroxyethyl)-1,4-naphthoquinone (ee) 2-(2-hydroxyethyl)-1,4-naphthoquinone (ff) 2-bromo-3-isopropoxy-1,4-naphthoquinone (gg) 2-diethylamino-3-chloro-1,4-naphthoquinone (hh) 2-(2-hexyloxy)-1,4-naphthoquinone (ii) 2-neo-pentyloxy-1,4-naphthoquinone (jj) 2-(2-n-pentyloxy)-1,4-naphthoquinone (kk) 2-(3-methyl-n-butoxy)-1,4-naphthoquinone (ll) 2-(6-hydroxy-n-hexoxy)-1,4-naphthoquinone (mm) 2-ethoxy-3-chloro-1,4-naphthoquinone (nn) 2-(2-hydroxyethyl)-3-bromo-1,4-naphthoquinone

22. A radiation-sensitive element according to claim 1 in which from 0.1 to 10 moles of cobalt(III)complex are present per mole of photoreductant.

23. A radiation-sensitive element according to claim 12 in which said adjuvant is present in a concentration of at least 0.5 mole per mole of said photoreductant.

24. A radiation-sensitive element according to claim 1 in which said radiation-sensitive layer incorporates a binder in a concentration of up to 99% by weight.

25. A radiation-sensitive element according to claim 24 in which said radiation-sensitive layer incorporates a binder in a concentration of from 50 to 90% by weight.

26. A radiation-sensitive element according to claim 1 in which said radiation-sensitive layer additionally includes a compound capable of forming a ligand of an optically dense cobalt(II) compound upon reduction of said cobalt(III)complex.

27. A radiation-sensitive element according to claim 26 in which said ligand forming compound is a chelating agent.

28. A radiation-sensitive element according to claim 26 in which said ligand forming compound is capable of forming at least bidentate chelates with cobalt.

29. A radiation-sensitive element according to claim 28 in which said chelating compound is chosen from the group consisting of formazan dyes, dithiooxamide, nitroso-arol, azo, hydrazones and Schiff base chelating agent.

30. A radiation-sensitive element according to claim 29 in which said chelating agent is chosen from the class con-sisting of compounds of the formula Z1-N=N-Z2, Z3-CH=N-NH-Z4 and Z5-CH=N-Z6 wherein each Z is a ring-bonded aromatic substituent and at least Z2, Z3, Z4 and Z5 are chosen to be capable of forming a chelate ligand.

31. A radiation-sensitive element according to claim 1 and, in combination therewith, image recording means overlying said radiation-sensitive layer.

32. A combination according to claim 31 in which said image recording means includes an ammonia responsive layer and said cobalt(III)complex includes at least one ammine ligand.

33. A combination according to claim 32 in which said ammonia responsive layer includes ninhydrin, o-phthalaldehyde or a combination thereof.

34. A combination according to claim 32 in which said ammonia responsive layer incorporates an ammonia bleachable dye.

35. A combination according to claim 34 in which said ammonia bleachable dye is a pyrylium dye.

36. A combination according to claim 32 in which said ammonia responsive layer is additionally radiation responsive.

37. A combination according to claim 36 in which said ammonia responsive layer is a diazonium salt containing layer.

38. A combination according to claim 36 and, in combination therewith, at least one ammonia permeable layer interposed between said radiation-sensitive layer and said ammonia responsive layer.

39. A radiation-sensitive element comprising (A) a support and, (B) as a coating, a radiation-sensitive layer comprised of 1) a cobalt(III)complex free of a sensitizable anion and including a µ-superoxodeca-ammine dicobalt(III) cationic moiety and 2) a photoreductant capable of forming a redox couple with the cobalt(III)complex upon exposure to actinic radiation longer than 300 nanometers in wavelength.

40. A radiation-sensitive element comprising (A) a support and, (B) as a coating, a radiation-sensitive layer comprised of 1) a cobalt(III)complex free of a sensitizable anion and including at least one hydrogen amine ligand and 2) a quinone having at least one quinone ring position adjacent a carbonyl group unsubstituted.

41. A process comprising (A) converting a photoreductant to a reducing agent by exposure to electromagnetic radiation of a wavelength longer than 300 nanometers and (B) reacting the reducing agent with a cobalt(III)-complex which is free of a sensitizable anion.

42. A process according to claim 41 comprising exposing a radiation-sensitive layer containing the photoreductant and the cobalt(III)complex to actinic radiation and heating the radiation-sensitive layer to stimulate reducing agent produced on exposure of the photoreductant to react with the cobalt(III)complex.

43. A process according to claim 42 in which the radiation-sensitive layer is heated to a temperature in the range of from 80 to 150°C.

44. A process according to claim 42 in which heating is undertaken after exposure.

45. A process according to claim 42 in which exposure occurs while the radiation-sensitive layer is heated above ambient temperature.

46. A process according to claim 42 additionally including the step of incorporating a chelating agent to react with a reaction product formed by reduction of the cobalt(III)-complex.

47. A process according to claim 42 in which the cobalt(III)complex includes an ammine ligand and ammonia is liberated from the radiation-sensitive layer upon heating and after exposure.

48. A process according to claim 47 in which the radiation-sensitive layer is substantially uniformly exposed and heated so that ammonia is substantially uniformly liberated from the radiation-sensitive layer.

49. A process according to claim 47 in which the radiation-sensitive layer is imagewise exposed and substantially uniformly heated so that ammonia is imagewise liberated from the radiation-sensitive layer.

50. A process comprising (A) exposing a radiation-sensitive layer containing a photoreductant and a ligand containing cobalt(III)complex free of a sensitizable anion to radiation longer than 300 nanometers wavelength longer than 300 nanometers to convert the photo-reductant to a reducing agent, (B) associating with the radiation-sensitive layer an image recording layer which is visibly responsive to at least one ligand contained within the cobalt(III)complex upon release thereof, and (C) heating the radiation-sensitive layer to stimulate reduction of the cobalt(III)complex with concomitant ligand release and transfer of the released ligand to the image recording layer.

51. A process according to claim 50 in which the radiation-sensitive layer is imagewise exposed and an image recorded within the image recording layer.

52. A process of forming a positive image comprising (A) associating with a radiation-sensitive layer con-taining a photoreductant and a cobalt(III)complex free of a sensitizable anion and containing at least one ammine ligand, a diazo image recording means, (B) imagewise exposing the diazo image recording means to actinic radiation, (C) uniformly exposing the radiation-sensitive layer to radiation of a wavelength longer than 300 nanometers to convert the photoreductant to a reducing agent, and (D) heating the radiation-sensitive layer to stimulate reduction of the cobalt(III)complex with concomitant release of ammine ligands and transfer of released ammonia to the diazo image recording means to form a positive image therein.

53. A process of forming a negative image comprising (A) associating a radiation-sensitive layer comprising a photoreductant and a cobalt(III)complex free of a sensitizable anion and including at least one ammine ligand with a diazo image recording layer, (B) imagewise exposing the radiation-sensitive layer to radiation of a wavelength longer than 300 nanometers to convert the photoreductant to a reducing agent and (C) heating the radiation-sensitive layer to stimulate reduction of the cobalt(III)complex with concomitant release of ammonia and transfer of the ammonia to the image recording layer to permit the formation of a negative diazo image.

54. A process according to claim 53 in which the diazo image recording layer is uniformly exposed to actinic radiation after the negative image is formed therein to stabilize the diazo image recording layer against printout in low density areas.

55. A process of forming positive images comprising (A) imagewise exposing a radiation-sensitive layer containing a photoreductant and a cobalt(III)complex free of a sensitizable anion to radiation longer than 300 nanometers in wavelength to convert the photoreductant to a reducing agent, (B) heating the radiation-sensitive layer to stimulate reduction of the cobalt(III)complex in exposed areas and there-after introducing into the radiation-sensitive layer leuco dye means which is imagewise oxidizable to a colored form by the cobalt(III)complex remaining in unexposed areas of the radiation-sensitive layer.

56. A process of forming positive images according to claim 55 in which the cobalt(III)complex includes a µ-super-oxodeca-ammine dicobalt(III) cationic moiety.