US3411904A - Photographic multicolor diffusion transfer process using dye developers and element - Google Patents

Description

Nov. 19, 1968 R. w. BECKER 3,411,904

FHOTOGRAPHIC MULTICOLOR DIFFUSION TRANSFER PROCESS USING DYE DEVELOPERS AND ELEMENT Filed May 19, 1964 R191 SUPPORT RECEPTION LAYER L KALINE PROCESSING COMPOSITION OVERCOAT LAYER BLUE SENSITIVE EMULSION LAYER YELLOW DYE DEVELOPER LAYER I NT E RLAYE R GREEN-SENSITIVE EMULSION LAYER MAGENTA DYE DEVELOPER LAYER INTERLAYER RED-SENSITIVE EMULSION LAYER CYAN DYE DEVELOPER LAYER SUPPORT YELLOW IMAGE l 27 MAGENTA IMAGE 2B CYAN IMAGE S iage 2 RichardWBeclcer IN VEN TOR.

By %MM @LR FJQ ATTORNEYS United States Patent 3,411,904 PHOTOGRAPHIC MULTICOLOR DIFFUSION TRANSFER PROCESS USING DYE DEVELOP- ERS AND ELEMENT Richard W. Becker, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Continuation-impart of application Ser. No. 71,314, Nov. 23, 1960. This application May 19, 1964, Ser. No. 368,490

11 Claims. (Cl. 96-3) ABSTRACT OF THE DISCLOSURE Photographic elements are provided comprising a support having coated thereon, in the order given, red, green and blue image-forming units comprising, respectively, a red sensitive emulsion layer having an underlying, contiguous cyan dye developer layer; a green sensitive emulsion layer having an underlying contiguous magenta dye developer layer; and, a blue sensitive silver halide emulsion layer having an underlying contiguous yellow dye developer layer. In accordance with the invention, the yellow dye developer layer is from .01 to .1 mil in thickness and contains from 25 to 250 mg. gelatin per square foot; each of the image-forming units is separated by gelatin interlayers which are A to 3 times as thick, and contain from 2 to 6 times as much gelatin as the yellow dye developer layer; and, the element contains a substantially colorless, water-insoluble hydroquinone which is soluble and difiusible in alkaline solution through the layers of the element.

This application is a continuation-in-part application of my copending application, Ser. No. 71,314 filed Nov. 23, 1960, now abandoned.

The present invention relates to the art of photography, and more particularly, to dye diffusion transfer systems utilizing dye developers.

Compounds which contain in the same molecule both the chromophoric system of a dye and a photographic silver halide developing moiety have been described in the photographic art as useful compounds in photographic elements for preparing color images by diffusion transfer processes. Such compounds are commonly called dye developers. Photographic elements containing such dye developers generally comprise a plurality of photosensitive silver halide emulsions wherein each of the emulsions is selectively sensitized to a different region of the spectrum. A dye developer is positioned contiguous to the silver halide in each of such emulsions. Such a photoelement is processed with an alkaline composition and the latent image is developed in the negative image areas with the dye developers, this development immobilizing the dye developers in such negative image areas, and the dye developers in the unexposed areas diffuse to the surface imagewise and are transferred to a reception layer or receiving sheet to form a positive multicolor image. Such color diffusion transfer processes are disclosed in US. Patent 2,983,606, and British Patent 804,971, as well as elsewhere in the literature.

Many problems are encountered in multicolor dye developer diffusion transfer systems that are different than corresponding monochrome systems and other multicolor systems. For example, in multicolor dye developer systems, the development products of one emulsion tend to affect the development of the other emulsions, the diifusion of a dye developer from a lower layer can be aifected, i.e., be hindered, by a dye developer or other substance in an upper layer, the exhaustion of the processing solution 3,41 1,904 Patented Nov. 19, 1968 ice by an outer layer may affect development of a lower layer and one layer may not develop to the extent of another layer, and particularly, one dye developer may not be immobilized sufiiciently to prevent it from transferring and causing color contamination of a dye image of another color. Also, a given dye developer may develop some grains of silver halide in the wrong emulsion layer with the result that an insuflicient amount of that dye developer is available for transfer and the corresponding colors are unsaturated. Thus a magenta dye developer may develop some grains of red-sensitive silver halide and become immobilized, this decreasing the magenta available to produce red colors which then appear unsaturated. Concomitantly, because of the undesired development of the red-sensitive emulsion layer by the magenta dye developer, some of the cyan dye developer which should have developed the red-sensitive emulsion layer is free to diifuse, this resulting in an even greater desaturation of the red colors. Degradation of color quality due to dye developer developing silver halide in the wrong emulsion layer is referred to as color drop-off.

It is an object of this invention to provide .a novel multicolor diffusion transfer process utilizing dye developers.

It is another object of this invention to provide a novel photographic process that is useful in preparing multicolor dye developer images having reduced color contamination.

It is another object of this invention to provide a novel dye diffusion transfer process for preparing multicolor dye developer images having reduced color drop-01f.

It is still another object of this invention to provide a new photographic element suitable for preparing multicolor dye developer images.

These and other objects of the invention are accomplished with light-sensitive photographic elements comprising a support having coated thereon three superposed dye image-forming units capable of recording red, green and blue light, each of such units comprising a gelatino silver halide emulsion layer and an underlying contiguous layer containing a dye developer in a gelatin substrate substantially complementary in color to the color of light recorded in the contiguous silver halide emulsion. The dye image-forming unit that records blue light is farthest from the support and contains a yellow dye developer, the dye image-forming unit that records red light is most proximate to the support and contains a cyan dye developer, and the dye image-forming unit that records green light and contains a magenta dye developer is positioned between the other units. In accordance with the invention, gelatin interlayers of a specified thickness are utilized on either side of the dye image-forming unit recording green light to separate it from the other dye image-forming units. The gelatin interlayers of the invention should be about to 3 times as thick as and containing about 2 to 6 times as much gelatin as the dye developer layer containing the yellow dye developer. The layer containing the yellow dye developer typically is about .01 to .1 mil in thickness and contains about 25 to 250 mg. of gelatin per square foot.

Another important feature of the photographic elements of the invention is the use of a substantially colorless and substantially water-insoluble hydroquinone soluble and diffusible in alkaline solution through the gelatin layers of the elements positioned in at least one of the layers on the emulsion side of the elements. Such hydroquinone compounds, in cooperation with the gelatin interlayers described above, produce results not attributable to either of these features separately. Also, the subject photographic elements are preferably processed or activated with alkaline processing compositions containing an onium compound that is soluble and ditfusible in alkaline solution through the gelatin layers of the elements.

The dye developer diffusion transfer system of the invention produces positive color image transfer prints that are particularly characterized as having improved color density and color purity.

Dye developers are well known in the photographic art. Such compounds function both as a silver halide developing agent and as a dye in photographic diffusion transfer systems. Dye developers are characterized as being relatively nondiffusible in colloid layers such as the hydrophilic organic colloids used in photographic emul sions at neutral pH, but dilfusible in the photographic elements in the presence of alkaline processing solutions. Generally, such dye developers are substantially insoluble in water, which property usually necessitates the use of organic solvents to incorporate the dye developers into the organic colloid layers of the photoelements. The dye developers are particularly characterized as containing both a chromophoric or dye moiety and at least one moiety having a silver halide developing agent function. Particularly useful dye developers are those wherein the chromophoric moiety is an azo or anthraquinone dye moiety and the silver halide developing moiety is a benzenoid moiety such as a hydroquinonyl moiety.

Representative dye developers of use in the dispersions of the invention have the general formula MN=ND in which M is an aromatic or heterocyclic ring or ring system such as a benzene, naphthalene, tetralin, anthracene, anthraquinone, pyrazole, quinoline, etc., ring which can be substituted with such groups as hydroxyl, amino, keto, nitro, alkoxy, aryloxy, acyl, alkylamido, arylamido, alkylaryl, carboxamido, sulfonamido, carboxyl or sulfo groups. D represents a silver halide developing agent moiety imparting the developing agent function to the dye developer such as a hydroquinonyl group which can be substituted with amino, alkylamino, alkyl, hydroxyl, alkoxyl or halogen groups.

A useful class of dye developers is disclosed in Australian Patent 220,276 and German Patent 1,036,640,

typical members of the class being listed below.

4- [p-(2,5-dihydroxyphenyl)-phenylazo] -5-acetamido-1- naphthol 4- [p- 2,5 '-dihydroxyphenethyl -phenylazo] -5-benzamidol-naphthol 1-phenyl-3-methyl-4- [p-( 2',5 '-dihydroxyphenethyl phenylazo -5-pyrazolone 2- [p-( 2,5 -dihydroxyphenethyl -phenylazo] -4-acetamidol-naphthol 2-[p-(2,5'-dihydroxyphenethyl)-phenylazo] -4-amino-1- naphthol 2- [p- 2,5 -dihydroxyphenethyl) -phenylazo] -4-methoxy l-naphthol 2-[p-(2,5'-dihydroxyphenethyl) -phenylazo] -4-ethoXy-1- naphthol 2- [p- 2,5 -dihydroxyphenethyl -phenylazo] -4-n-propoxyl-naphthol 1-phenyl-3-N-n-butyl-carboXamido-4- [p- 2,5 '-dihydroxyphenethyl) -phenylazo] -5-pyrazolone 1-phenyl-3 -N-n-hexylcarboxamido-4- [p- 2',5 -dihydroxyphenethyl -phenylazo 1 -5-pyrazolone 1-phenyl-3-carbethoXy-4- [p- 2,5 '-dihydroxyphencthyl phenylazo] -5-pyrazolone 2- p-( 2',5-dihydroxyphenethyl) -phenylazo] -4-isopropoxy- 1 -naphthl 1-phenyl-3-N-cyclohexylcarboxamido-4- [p- 2,5 '-dihydroxyphenethyl) -phenylazo] --pyrazolone 1-pheny1-3-pheny-l-4- [p- 2',5 -dihydroxyphenethyl) phenylazo] -5-pyrazolone 2- (4- [p- 2",5 "-dihydroxyphenethyl -phenylazo -ocnaphthylazo-4-methoxyl-naphthol 1-phenyl-3-amino-4- (4'- [p- 2",5 "-dihydroxyphenethyl phenylazo] -2',5 -diethoxyphenylazo -5-pyrazolone l-acetoXy-Z- [p- (pi-hydroquinonylethyl phenylazo] -4- methoxy naphthalene 4-isobutoxy-2- [p-(B-hydroquinonylethyl)-phenylazo] l naphthol 1-acetoXy-2- [p- ,B-hydroquinonylethyl -phenylazo] -4- propoxy naphthalene 2- [p- 2,5 '-dihydroXy-4'-methylphenethyl) -phenylazo] -4- propoxyl-naphthol 1-phenyl-3- [N- fl-ethylhexyl) -carboxamido] -4- [p- B hydroquinonylethyl -phenylazo] -5-pyrazolone 1-phenyl-3- (N-n-heptyl -carboxamido-4- [p- S-hydroquinonylethyl -phenylazo] -5-pyrazolone l (o-carboXyphenyl)-3-phenyl-4-[p-(2,5-trifluoro acetoxyfl-phenylethyl)-phenylazo] -5-hydroxy pyrazole lactone 1- (o-carboxyphenyl -3-N-phenylcarboxaInido-4- [pphydroquinonylethyl -phenylazo] -5-hydroxypyrazole lactone Another useful class of dye developers is disclosed by British Patent 804,971 and British Patent 804,973, several being listed below. 1,4-bis 2,5'-dihydroxyanilino -anthraquinone 1,5 -bis( 2',5 -dihydroxyanilino) -4,8-dihydroxy-anthraquinone 1,4-bis B- 3 ,4-dihydroxyphenyl -ethylamino] -anthraquinone 1,4-bis 3-(2,5-dihydroxyphenyl)-isopropylamino]- anthraquinone 1,4-bis ,B- (2,5-dihydroxyphenyl -ethylamino] -anthraquinone l-chloro-4- {3- 2',5-dihydroxyphenyl -ethylamino] anthraquinone N-monobenzoyl-1,4-bis [fl-( 3 ,4'-dihydroxyphenyl -ethylamino] -anthraquinone N-monobenzoyl-1,4-bis[fl-(2,5'-dihydroxyphenyl)-ethylamino] -anthraquinone 5,8-dihydroxy-1,4-bis fi-hydroquinonyl-a-methyl -ethylamino]-anthraquinone (Compound I) 1,4-bis (,s-hydroquinonyl-u-ethyl) -ethylamino] -anthraquinone 5-hydroxy-1,4-bis[ fl-hydroquinonyl-u-methyl -ethylamino] -anthraquinone 1- (,8-hydroxy-a-ethyl-ethylamino -4- (fi-hydroquinonyl-amethylethylamino-anthraquinone 1-(butanol-2'-amino)-5,S-dihydroxy-4-hydroquinony1- isopropylamino-anthraquinone Also useful are the following dye developers. Cyanurated dye developers such as 2-hydroquinoneamino-4-(pphenyl-azo) anilino 6 hydro-xy-4-triazine described in Canadian Patent 579,038. Anthraquinone dye developers such as 1,4-bis(2',5-dihydr0xyanilino) anthraquinone and 1,4-diamino-N-(fi-2',5'-dihydroxyphenyl a methylethyl)-2,3-anthraquinone dicarboximide. Amino-substituted anthraquinone dye developers such as prepared by reaction of 1-amino-4-(p-aminoanilino)-anthraquinone-2- sodium sulfonate with chloroacetamido hydroquinone monobenzoate. Dye developers obtained by reaction of 1- phenyl 3 amino-4-phenylazo-5-pyrazolone or 1,4 bis (5 aminoethylamine) anthraquinone with homogentisic acid lactone or acid chloride, or gentisic acid chloride, e.g., 1-phenyl-3-(2,5-dihydroxy-phenylacetamido-4- phenylazo-S-pyrazolone described in Canadian Patent 577,021. Naphthamide dye developer such as 1-(2,5-dimethoxyphenylazo) 2 hydroxy N (2',5' dihydroxyphenyl)-3-naphthamide described in French Patent 1,168,- 292. Diazo dye developers such as 2-[p-(1-hydroxy-3,6-disulfo-8-amino-2-naphthylazo)-3,3 dimethoxybisphenyleneazo]-hydroquinone and 2 (2',5' dimethoxy 4- [p-(2";5" dihydroxyphenethyl) phenylazo] phenylazo)-l,8 naphthalene diol-3,6-disulfonic acid. Arylazonaphthol dye developers, e.g., 1 amino-4-phenylazo-2- naphthol. Anthrapyridone dye developers, e.g., 1-acetyl-3- 13-(2',5'-dihydroxyphenyl) ethyl 6 ,8 (2',5 dihydroxyphenyl) ethylamino anthrapyridone. Thiohydroquinolyl dye developers, e.g., l phenyl-3-methyl-4-[p- (2. 5' dihydroxyphenylthioethyl) phenyl azol-S-pyrazolone described in Belgian Patent 563,344. Ortho-coupled dye developers exhibiting limited sensitivity to changes of pH, e.g., 2-[p-(2",5 dihydroxyphenoxy) phenylazo]- 4 methoxy-l-naphthol and 1-phenyl-3-methyl-4-[p-hydroquinolyl sulfonyl) phenylazo]-5-pyrazolone. Oxalyl ester dye developers, e.g., l phenyl-3-amino-4-[p-(2',5'- bis ethoxalyloxyphenethyl) phenylazo]-5-pyrazolone. Leuco compounds can also be used similarly, e.g., lphenyl 3 methyl 4 (2-rnethyl-4'-diethylamino) anilino 5 pyrazolone, which do not exert a filtering action on underlying emulsion layers and which are immobilized in the developed regions, diffuse imagewise from undeveloped areas to the reception layer and are oxidized to colored images therein. Additional suitable dye developers are disclosed in Belgian Patent 554,935, British Patents 804,971, 804,974-5 and French Patent 1,168,292.

In the photographic elements useful in the invention, the dye developers are preferably incorporated in gelatin vehicles or carriers comprising the layers of the photographic element dissolved in high-boiling or crystalloidal solvents and dispersed in finely-divided droplets. In preparing such dispersions of dye developers, high-boiling or substantially water-immiscible organic liquids having boiling points above about 175 C. are utilized. The highboiling solvent can be used alone in dissolving the dye developer and in forming the dispersion or it can be mixed with a low-boiling organic solvent (e.g., boiling at least 25 C. below the boiling point of the higher boiling solvent), or a watersoluble organic solvent, as an auxiliary solvent to facilitate solution of the dye developer. A preferred range of proportions of high-boiling solvent to auxiliary is 1/0 to l/lO on a weight basis. Such auxiliary solvents can be readily removed from the colloidal vehicle by air-drying a chilled, noodled dispersion or by continuous water washing. Typical high-boiling, water-insoluble solvents that can be used to dissolve dye developers in preparing the dispersions of the invention are described on page 2, col. 2 and page 3, col. 1 of US. Patent 2,322,027.

The dye developers utilized in the photographic elements useful in the invention can also be incorporated into vehicles soluble in organic solvents which are also solvents for the dye developers. Likewise, other incorporating techniques for the dye developers such as ballmilling can be utilized.

Each of the dye developers is positioned in a gelatin sublayer contiguous to the respective silver halide emulsion layers. A silver halide emulsion layer and its contiguous dye developer-containing layer comprises a dye image-forming unit of the invention. The dye developers are substantially complementary in color to the color or the light recorded or spectral sensitivity of the silver halide emulsions contiguous thereto.

A wide variety of colorless hydroquinone derivatives can be utilized in the dye developer diffusion transfer systems of the invention. Such colorless hydroquinone derivatives are substantially insoluble in water and diffusible in the hydrophilic organic colloids comprising the present photographic elements in the presence of alkaline processing compositions. Typical suitable colorless hydroquinone derivatives are listed below.

Phenylhydroquinone 2-hydroxyphenylhydroquinone phenoxyhydroquinone 4-methylphenylhydroquinone 1,4-dihydroxynaphth alene 2-(4-aminophenethyl)-5-bromohydroquinone 2-(4-aminophenethyl)-5-methylhydroquinone 4'-aminophenethylhydroquinone 2,S-dimethoxyhydroquinone 2,5-dibutoxyhydroquinone m-xylohydroquinone bromohydroquinone 3 ,6-dichlorohydroquinone 2-dimethylaminomethyltoluhydroquinone Z-cyclohexylhydroquinone sec. butylhydroquinone 2,5-dichlorohydroquinone 2,5-diisopropylhydroquinone 2,5-diiodohydroquinone 3-chlorotoluhydroquinone tetrachlorohydroquinone 2,5-diphenylhydroquinone 2,S-diresorcylhydroquinone 2,5dioctylhydroquinone dodecylhydroquinone In the present dye developer diffusion transfer systems, the hydroquinone derivative can be present in any of the layers of the light-sensitive or negative element such as in an overcoating layer, in a silver halide emulsion layer, in a dye developer layer, or in an interlayer. The hydroquinone derivatives are preferably used in one or more layers of the light-sensitive element in quantities of the order of about 10 to 100 mg. or more per square foot. However, the quantity used can be widely varied and depends in part on the amount of silver halide in the emulsion layers.

A Wide variety of diffusible onium compounds can also be utilized in the present invention. Such onium compounds, that is, compounds that contain an organic cation, are diifusible in the hydrophilic organic colloids comprising the present photographic elements in the presence of alkaline processing compositions. Such onium compounds are typically quaternary ammonium compounds, quaternary phosphonium compounds or tertiary sulfonium compounds. The onium compounds can be used .as hydroxides or as other types of salts. Typical suitable quaternary ammonium compounds have the formulas typical suitable quaternary phosphonium compounds have the formula and, typical suitable tertiary sulfonium compounds have the formula R12 Rr4 X- a In the above formulas: R to R are each organic radicals such as alkyl radicals, aryl radicals, aralkyl radicals of the benzene series, and including substituted .alkyl, aryl or aralkyl radicals, the alkyl chains generally being 1 to 18, and preferably 1 to 4, carbon atoms, and the aryl radicals preferably being phenyl; X is an anion including hydroxyl or an anion derived from an acid such as bromide, chloride, p-toluene sulfonate, perchlorate or the like; and Z and Z each represent the nonmetallic atoms necessary to complete a heterocyclic ring generally having 5 to 10, .and preferably 5 or 6 atoms in the heterocyclic nucleus such as carbon, nitrogen, oxygen, selenium and sulfur atoms to form such heterocyclic rings as pyridine, quinoline, benzoquinoline, benzoxazole, benzoselenazole, thiazole, benzothiazole, piperidine, naphthothiazole, benzimidazole, naphthi-midazole, naphthoxazole, naphthoselenazole, isoquinoline, pyrrole, pyrrolidine and the like, such heterocyclic rings being suitably substituted with such substituents as halogens, lower alkyl radicals .and halo lower alkyl radicals.

A particularly useful class of onium compounds are heterocyclic quaternary ammonium compounds that are capable of forming diffusible methylene bases in alkaline processing compositions. Such quaternary ammonium compounds can be illustrated by the formula wherein: X is an anion as described above, 11 is an integer of or 1, Z represents the nonmetallic atoms necessary to complete a heterocyclic ring as described above for Z and Z but is preferably a pyridine ring, R and R are either hydrogen atoms or lower alkyl radicals having 1 to 4 carbon atoms, and R is an organic radical as described above for R to R Typical onium compounds that can be utilized in the present invention are listed below.

l-benzyl-Z-picolinium bromide 1- 3 -bromopropyl -2apicolinium-p-toluenesulfonate l-phenethyl-Z-picolinum bromide 1'y-phenylpropyl-2picolinmm bromide 2,4-dimethyll-phenethylpyridinium bromide 2,6-dimethyll-phenethylpyridinium bromide S-ethyI-Z-methyl-l-phenethylpyridinium bromide u-picoline-B-naphthoylmethylbromide l-fl-phenylcarbamoyloxyethyl-2-picolinium bromide anhydro-l- (4-sulfobutyl) -2-picolinium hydroxide 2-ethyl-l-phenethylpyridinium bromide l- [3- (N-pyridinium bromide) propyl]-2-.picolinium-p toluene-sulfonate 1-methyl-2-'picoliniump-toluenesulfonate l-phenethyl-2,4,6-trimethylpyridinium bromide 1-phenethyl-4-n-propylpyridinium bromide 4- -hydroxypropyl-lwphenethylpyridinium bromide l-n-heptyl-2-picoliuiutm bromide Z-isopropyl-l-phenethylpyridinium bromide tetraphenylammonium bromide tetraethylammonium bromide N-ethylpyridinium bromide N,N-diethylpiperidinium bromide ethylene-bis-pyridinium bromide l-iphenethyl-3-picolinium bromide cetyltrimethylammonium bromide polyethylene oxide bis-pyridinium perchlorate 3-methyl-2-ethylisoquinolium bromide B-methylisoquinolinium methyl-p-toluenesulfonate 1-ethyl-2-methyl-3-phenethylbenzimidazolium bromide ,6-dichlorol-ethyl-2-methyl-3- 3-sulfobutyl) benzim-idazolium betaine lauryldimethylsulfoniump-toluenesulfonate nonyldimethylsulfoniu-m-tp-toluenesulfonate octadimethylsulfonium-p-toluenesulfonate butyldimethylsulfonium bromide triethylsulfonium bromide dodecyldimethylsulfonium-p-toluenesulfonate decyldimethylsulfonium-p-toluenesulfonate phenyldimethylsulfonium bromide phenethyldimethylsulfonium bromide tetraethylphosphonium bromide ethylene-bis-oxymethyltriethylphosphonium bromide tetraphenylphosphonium bromide phenethyltrimethylphosphonium bromide In dye developer diffusion transfer systems, the onium compounds are preferably utilized in the alkaline processing composition, although the onium compounds can also be utilized in the reception sheet, or less desirably, in one or more layers of the light-sensitive element, or in .at least two of such positions.

The onium compounds can be used in a wide range of concentrations in dye developer diffusion transfer systems, optimum amounts varying with the particular onium compound. Typical useful amounts of the onium compounds in the alkaline processing compositions range from about 2% to 15% by weight of onium compound based on the weight of the' processing composition.

Cit

When water-soluble silver halide solvents are employed in processing compositions used in dye developer transfer systems, particularly in conjunction with onium compounds and colorless hydroquinone derivatives as described above, further improvement in color quality results. Preferred silver halide solvents are thiosulfates such as sodium, potassium and ammonium thiosulfate. Other suitable silver halide solvents include thiocyanates, N,N- diethyl-1,3-propanediamine, triethanol amine, aminoethanol, ammonium hydroxide, and the like. Such silver halide solvents are preferably incorporated in the alkaline processing composition in amounts of about .8 to 2% by weight, although they can also be positioned in the reception layer for the dye images. Substantially no silver halide is transferred to the reception layers, and thus, the present process is to be distinguished from silver halide diffusion transfer processes.

The silver halide emulsions utilized in preparing photographic or light-sensitive elements used in the present diffusion transfer systems can be any of the conventional negative-type, developing-out emulsions. Typical suitable silver halides include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, silver chlorobromoiodide and the like. Mixtures of more than one of such silver halides can also be utilized. In accordance with usual practice, such silver halide emulsions can contain spectral sensitizers, speed-increasing addenda, hardeners, coating aids, plasticizers, anifoggants and the like conventional emulsion addenda.

In preparing such silver halide emulsions, as well as in preparing the various layers of photographic elements used in the present dilfusion transfer systems, including the layers containing the dye developers and colorless hydroquinone derivatives, interlayers, topcoat layers and the like, hydrophilic organic colloids composed primarily of gelatin are utilized as the vehicle or carrier. Minor amounts of other hydrophilic colloids or carrier materials can be used with gelatin such as polyvinyl alcohol and its water-soluble derivatives and copolymers, watersoluble copolymers such as polyacrylamide, immidized polyacrylamide, etc., and other water-soluble film-forming materials that form water-permeable coats such as colloidal albumin, water-soluble cellulose derivatives, etc., can be utilized in preparing the photographic elements. However, such vehicles or carriers preferably consist essentially of gelatin.

The various layers utilized in preparing the diffusion transfer photographic elements used in the process of the invention can be coated on a Wide variety of photographic supports. Typical supports include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film, polyethylene film, polypropylene film, paper, polyethylene-coated paper, glass and the like.

Similarly, a wide variety of receiving sheets can be utilized to receive the transfer images from the photographic elements. Typical reception layers for receiving sheets include such materials as linear polyamides, proteins such as gelatin, polyvinyl pyrrolidones, poly-4-vinyl pyridine, polyvinyl alcohol, polyvinyl salicylal, partially hydrolyzed polyvinyl acetate, methyl cellulose, regenerated cellulose, or mixtures of such. These reception layers can be coated on a suitable support of the type def scribed above for the light-sensitive elements of the invention and including transparent as well as opaque supports. Also, receiving sheets that release acidic material such as that derived from an acidic polymer or other acidic compound at a controlled rate as are described in U.S. Patent 2,584,030 are particularly useful. Such acidic materials are typically positioned in layers on the receiving sheet below the dye developer reception layer, there suitably being a spacer layer between the acid layer and the mordanting layer to control the release of acidic material. Such acidic materials serve to neutralize residual portions of the alkaline activator on the receiving sheet.

A wide variety of nonditfusible cationic or basic dyemordanting compounds can be used in liquid permeable reception layers including amines such as polymeric amines, quaternary ammonium compounds, quaternary phosphonium compounds and tertiary sulfonium compounds. Such mordants are nondiffusible in the alkaline processing composition and contain at least one hydrophobic ballast group. The receiving sheets can also contain development arrestors such as mercaptoazoles and iodides.

Light-sensitive elements containing integral reception layers for dye developer images can also be utilized. Such integral reception layers can be coated beneath the emulsion and dye developer layers near the support. A stripping layer coated over the integral reception layer can be used to facilitate the removal of the overcoated layers after the diffusion of the dye developer images to the reception layer.

The processing compositions or activators used to initiate development of the exposed light-sensitive elements in accordance with the invention are strongly alkaline. Such processing compositions generally have a pH of at least 12 or contain at least .01 N hydroxyl ion. Alkali metal hydroxides, such as sodium hydroxide, and sodium carbonate, are advantageously used in the composition for imparting such high alkalinity. However, volatile amines such as diethyl amine can also be used, such amines having the advantage of being volatilized from the prints to leave no residue of alkali.

Camera apparatus of the type useful for exposing and processing image dilfusion transfer systems have been described, for example, in US. Patent 2,435,717. Such cameras permit successive exposure of individual frames of the photosensitive element as Well as processing of exposed frames. With such cameras, the exposed portion of the photosensitive element is brought in superposed relation with a portion of an integral print receiving element with a container for alkaline processing material therebetween, the alkaline processing material desirably containing a viscosity increasing agent such as hydroxyethyl cellulose or carboxymethyl cellulose. The film assembly is then drawn between a pair of pressure rollers which rupture the processing composition container and spread the alkaline processing composition between and in contact with the photosensitive element and the corresponding registered area of the print receiving element. The photosensitive element and print receiving element during the spreading of the container contents become formed into a combination wherein the photosensitive element and print receiving element are so superposed with respect to each other that the spread alkaline processing composition has access to both of the elements. This superposed relationship between the photosensitive and print receiving elements is maintained until the elements are stripped apart following the deposit on the print receiving element of the dye developer forming the final positive color image.

The processing of photographic elements in the present diffusion transfer process can also be effected in accordance with the invention outside of camera apparatus. A typical suitable processing means is illustrated by FIG. 2 of the drawing described hereinbelow.

In the accompanying drawing are shown in enlarged cross-sectional view representative elements and processing means employed in the invention.

In FIG. 1 of the drawing is shown in flow-sheet form a typical process embodying our invention according to which in Stage 1 the light-sensitive element comprises support 10, layers 11, 12 and 13 containing subtractively colored cyan, magenta and yellow dye developers, respectively, light-sensitive silver halide emulsion layers 14, 15 and'16 sensitive to red, green and blue light respectively, feature gelatin interlayers 17 and 18 described in detail herein separating the green-sensitive emulsion and its contiguous subtractively colored magenta dye developer layer from the other layers and overcoat layer 19, the colorless hydroquinone derivatives described above typically being positioned in layer 19. A receiving sheet comprising support 20 having coated thereon reception layer 21 is superposed to receive dye images transferring by dilfusion from the light-sensitive element. Positioned between the light-sensitive element and the receiving sheet 1s a rupturable container or pod containing alkaline processing composition 22. Upon rupture of the container hold ng alkaline processing composition 22, such as by passing the assembly between rollers in a camera, the contents of the container are substantially uniformly spread across a predetermined area of the sensitive element. The viscous processing composition penetrates through layers 19 to 11, latent images develop in lightsens tive layers 14, and 16 and dye developers in contiguous layers 11, 12 and 13 respectively rendered nondrlfusing in areas corresponding to latent image or neganve areas such as 23, 24 and 25, and the dye developers 1n the remaining or positive image areas diffuse imagewlse 1n register to mordant or reception layer 21 of the receiving sheet. Stage 2 of FIG. 1 illustrates receiving sheet support with reception layer 21 containing transferred dye developers to form subtractively colored positive images, namely, yellow image 26, magenta image 27 and cyan image 28. FIG. 2 of the drawing illustrates a typical lightlm-pervious enclosure useful for processing exposed rolls ot film containing silver halide emulsion layers and dye developers of the type described above. In utilizing the processing means of FIG. 2, film 30, wound emulsion srdeanwards, is passed between rollers 31 and 32. Roller 32 1S immersed in alkaline processing composition 33. Roller 32 transfers portions of alkaline processing compos1t1on 33 to the emulsion layers on film 30. Thereafter film is conveyed between rollers 35 and 36 where the emulsion layer side of film 30 is brought into contact with mordanted receiving sheet 37 to form sandwich 38. In sandwich 38, the exposed silver halide in each emulslon layer develops, .continguous dye developers become immobilized and unreacted dye developers transfer to mordanted receiving sheet 37. Thereafter sandwich 38 is conveyed over roller 39 and stripped apart to provide posltrve dye developer images on mordanted receiving sheet 37 at 40.

The following examples will serve to further illustrate the present invention.

EXAMPLE I A photographic element having the structure substant1ally as shown in FIG. 1 of the drawing (layers 10 to 19) was prepared by coating successively the following layers on a subbed cellulose acetate film support:

(l) Cyan dye developer layer (e.g., layer No. 11 of FIG. 1).A coating of the cyan dye developer, 5,8- dlhydroxy 1,4 bis[(fl hydroquinonyl a methyl) ethylamino]-anthraquinone, dissolved in N-n-butylacetanilide, dispersed in gelatin and coated at a coverage of 210 mg. per square foot of the cyan dye developer and 250 mg. per square foot of gelatin. The dye developer dispersion was prepared by adding to an aqueous gelatin solution 1 part by weight of the cyan dye developer dissolved in 1.5 parts 'by weight of N-n-butylacetanilide and 2 parts by weight of 4-methylcyclohexanone in the presence of a sodium diisopropylnaphthalene sulfonate dispersing agent. The mixture was passed through a colloid mill several times, chill set, shredded, dried to volatilize the 4-methylcyclohexanone, melted and coated.

(2) Red-sensitive emulsion layer (e.g., layer No. 14 of FIG. 1).A coating of a developing-out negative gelatino-silver bromoiodide (6% iodide) emulsion sensitized to red light was coated at a coverage of mg. per square foot of silver and 200 mg. per square foot of gelatin.

(3) llnterlayer (e.g., layer No. 17 of FIG. l).A coating of gelatin at coverages described below.

(4) Magenta dry developer layer (e.g., layer No. 12 of FIG. l).A coating of the magenta dye developer, 2 [p (2',5 dihydroxyphenethyl) phenylazo] 4 npropoxy-l-naphthol, dissolved in N-n-butylacetanilide dispersed in gelatin and coated at a coverage of 60 mg. per square foot of the dye developer, 75 mg. per square foot of gelatin and 60 mg. per square foot of N-n-butylacetanilide. The dispersion of the dye developer was prepared by dispersing in an aqueous gelatin solution 1 part by weight of the dye developer in 2 parts by weight of cyclohexanone and 1 part by weight of N-n-butylacetanilide in the presence of the dispersing agent, sodium diisopropylnaphthalene sulfonate. The resulting mixture was passed through a colloid mill several times, chill set, washed to remove the cyclohexanone, melted and thereafter coated.

(5) Green-sensitive emulsion layer (e.g., layer No. of FIG. l).A coating of a developing-out negative gelatino-silver bromoiodide (6% iodide) emulsion sensitized to green light was coated at a coverage of 75 mg. per square foot of silver and 70 mg. per square foot of gelatin.

(6) Interlayer (e.g., layer No. 18 of FIG. l).A coating of gelatin at coverages described below.

(7) Yellow dye developer layer (e.g., layer No. 13 of FIG. 1).-A coating of the yellow dye developer, l-phenyl-3 N n hexylcarboxamido 4 [p (2,5 dihydroxyp'henethyl)phenylazo]-5-pyrazolone, dissolved in ditetrahydrofurfuryl adipate and dispersed in gelatin was coated at a coverage of 75 mg. per square foot of the dye developer, 50 mg. per square foot of gelatin and mg. per square foot of ditetrahydrofurfuryl adipate. The dispersion was prepared by dispersing in an aqueous gelatin composition, 1 part by weight of the dye developer dissolved in .5 part by weight of ditetrahydrofurfuryl adipate and 2 parts by weight of ethylene glycol monobenzyl ether in the presence of a sodium diisopropylnaphthalene sulfonate dispersing agent. The mixture was passed through a colloid mill several times, the resulting dispersion chill set, washed to remove the ethylene glycol monobenzyl ether, melted and coated.

(8) Blue-sensitive emulsion layer (e.g., layer No. 16 of FIG. l).A coating of a developing-out negative gelatino-silver bromoiodide (6% iodide) emulsion that is inherently sensitive to blue light was coated at a coverage of 65 mg. per square foot of silver and mg. per

square foot of gelatin.

(9) Overcoat layer (e.g., layer No. 19 of FIG. 1).- A gelatin coating containing dispersed therein the colorless auxiliary developer, 4-methylphenylhydroquinone (referred to hereafter as MPHQ), dissolved in di-nbutylphthalate at a coverage of 120 mg. of gelatin per square foot and 40 mg. of MPHQ per square foot. The dispersion was prepared as follows:

Hydroquinone derivative dispersion D-l Part A 4'-methylphenylhydroquinone g 136 Methyl alcohol ml 136 Di-n-butylphthalate ml 272 Heat at 70 C. to dissolve, then cool to 10 C.

4 Part B 10% gelatin solution g 1360 Water ml 1360 Mucochloricacid (2.7% aqueous solution) ml 136 Heat to 40" o.

Part A was slowly added to Part B with the aid of mechanical agitation. The solution obtained was then passed through a colloid mill five times. The colloid mill was then rinsed and the dispersion was adjusted to a Weight of 3775 g., chill set and stored in a refrigerator. 7

The coating composition for the overcoat layer (e.g., Layer 19 of FIG. 1) was prepared as follows:

Part I Dispersion D-l g 3,775 Water ml 2,225

Heat to 40 C.

In order to demonstrate the effect of varying amounts of gelatin in the interlayers (e.g., layers 17 and 18 of FIG. 1), several films having the basic structure described above were prepared in which the gelatin content of layer 17 was 75, 150 and 200 mg. per square foot 2 ad for layer 18 was 75, 150 and 300 mg. per square foot These films are designated as Films A, B and C respectively in the tables below. Similar films containing no MPHQ in layer 19 were prepared and are designated Films D, E and F in the tables below. The thicknesses in mils of the layers of Films A, B and C are shown in Table I.

TAB LE I Layer N 0. (Corresponding to Fig. 1 of the drawing) Film:

A 0. 07 0. 06 0. O4 0. O1 0. 07 O. 05 0. 02 0. 13 0. 23 B 0. 06 0. O7 0. 04 0. 03 0. 07 0. 06 0. 04 O. 14 O. 24 C 0. O6 0. 07 0. O4 0. 04 O. 07 O 06 0. 07 0. 15 0. 24

It can be seen from these measurements that in Films B and C, the interlayers, .17 and 18, are at least or 75% as thick as the yellow dye developer layer, 13. When crosssections of these films are viewed at a magnification of the order of l500 in Film A layers 12 and 15 appear to almost touch layers 14 and 13 respectively, whereas in Films B and C, layers 12 and 15 are distinctly separated from layers 14 and 13 as illustrated in FIG. 1', Stage 1 of the drawing. The films were each exposed under a step tablet to red, green and blue light and each wetted with either Activator I or Activator II in contact with either Receiving Sheet A or B, the activators and receiving sheets being described below. The films and the receiving sheets were left in contact for 3 minutes at F. and then stripped apart to give multicolor images on the receiving sheets. As a result the silver halide developed in exposed areas 23, 24 and 25 of each sample, and the dye de velopers in the contiguous areas of layers 13, 12 and 11 thereunder become immobilized as a function of the development and the unreacted dye developers ditfused imagewise and in register to the recei ing sheet to yield a colored positive image composed of mages 26, 27 and 28 as shown in Stage 2 of the drawings. In this process, the use of the interlayers of suitable thickness in cooperation with the colorless hydroquinone auxiliary developer, 4-methylphenylhydroquinone, the dye developers in each of layers 11, 12 and 13 become immobilized at the required rate, extent and in the proper layers, particularly when the processing was carried out in the presence of an onium compound. Density measurements were then made upon the resulting neutral scale and red scale of each print through red, green and blue filters to obtain the density values shown in Table 11 below. The activators or alkaline processing compositions referred to had the following composition:

Activator I An aqueous solution containing 3.5% high viscosity hydroxyethyl .cellulose 4.5% sodium hydroxide, 2% benzotriazole, 2% l-benzyl-Z-picolinium bromide and 1% sodium thiosulfate.

Activator II An aqueous solution containing 3.5% high viscosity hydroxyethyl cellulose 4.5% sodium hydroxide, 2%

*High viscosity hydroxyethyl cellulose sold by Hercules Powder Co. as Natrosol 250 Type H having a. viscosity of about 10,00015,000 cps. at 25 C. as 2% aqueous solution.

A paper support carrying a gelatin (300 mg. per square foot) layer containing a mixture of poly-4-vinyl pyridine mordant (300 mg. per square foot) and l-phenyl-S-mercapto tetrazole mg. per square foot).

Receiving Sheet B A paper support carrying a gelatin (300 mg. per square foot) layer containing a mixture of poly-4vinyl pyridine (300 mg. per square foot), l-phenyl-S mercapto tetrazole (15 mg. per square foot) and l-phenethyl-Z-picolinium bromide (100 mg. per square foot).

light, the dye image-forming unit recording blue light being furthest from the support and the dye image-forming unit recording red light being most proximate to the support, each of said image-forming units comprising a gelatino-silver halide emulsion layer and an underlying contiguous gelatin layer containing a dye developer substantially complementary in color to the color of light recorded in the contiguous gelatino-silver halide emulsion layer, a substantially colorless and substantially waterinsoluble hydroquinone soluble and diffusible in alkaline solution through the layers of said element positioned in at least one of the layers on the emulsion side of said element, and gelatin interlayers separating the said imageforming unit recording green light from the said imageforming unit recording red light and the said image- TABLE II Layer 18 Layer 17 Red Scale Density Ratio of Test Neutral Scale Dmin' 1st Step Cyan to N 0. Film Activator Receiver mgJgel/ Thickmg. lgel/ Thick- Magenta It." ness it. ness R G B R G B Dye (mils) (mils) Densities D (No MPHQ)--- I A 75 .01 75 .02 .34 .23 .33 .78 1.27 1.67 1;1.e3 E (No MPHQ) 1--.- 150 03 150 04 .35 .27 49 67 1.34 1.81 1:2. 0 F (No MPHQ) 200 04 300 07 28 .25 40 56 1. 43 1. 85 1:2. 56 A (With MPHQ) I A-.. 75 01 75 02 26 24 26 60 1. 03 1. 59 1:1. 73 B (With MPHQ). I 150 03 150 04 22 22 24 39 1. 12 1. 74 1:2. 89 C (With MPHQL- 1.- 200 04 300 07 21 25 23 1. 26 1. 72 1:5. 5 D (No MPHQ)--- II 75 01 75 02 .22 .87 .55 .75 1.55 1. 85 1:2. 08 E (No MPHQ) II- 150 03 150 04 20 54 94 70 1. 61 1. 93 1:2. 32 F (No MPH 200 04 300 07 .14 51 1. 08 64 1. 70 1. 91 1:2. 68 A (With MPHQL- I1. 75 01 75 02 18 41 1. 17 1. 56 1:2. 94 B (With MYHQ)" II- 150 03 150 O4 15 3O 43 34 1. 29 1. 73 1:3. 82 C (With MPHQ)" II A--. 200 .04 300 07 1,4 .27 .42 .30 1.48 1. 88 1:4. 95 13 D (No MPHQ) 75 01 75 O2 .27 .39 60 79 1. 41 1. 79 1:1. 79 E (No MPHQ) II 150 03 150 O4 27 40 66 71 1. 1. 87 1:2. 04 F (No MPHQ) II 200 04 300 07 24 41 76 61 1. 6O 1. 92 1:2. 64 A (With MPHQ) 75 01 75 02 20 22 28 49 1. 06 1. 57 1:2. 17 17 B (With M'PHQ) 150 03 150 04 16 19 28 29 1. 15 1. 71 1 4. O0 18 C (With MPHQ) II B 200 04 300 07 20 .23 .31 .26 1. 36 1. 86 1:5. 25

The data in Table 11 illustrates the improved multicolor transfer images that result from the novel features of the present dye developer difiusion transfer system. The data particularly illustrates the retarding of the diffusion of the magenta dye developer to the red-sensitive emulsion layer, and the retarding of the difiusion of the cyan dye developer upward, to produce red colors having less contamination with other colors and more saturation in accordance with the invention. Such improvements are indicated by substantial decreases in the ratio of cyan to magenta dye densities in the red scale, as measured by red (R) light and green (G) light. Tests 10, 11 and 12 illustrate the cooperation of the feature gelatin interlayers and the auxiliary hydroquinone developer to produce the improvements of the invention. Tests 4, 5 and 6, as well as Tests 16,- 17 and 18, illustrate the further cooperating effect of an onium salt in the system with the feature gelatin interlayers and auxiliary hydroquinone developer. Similar improvements are not obtained with other developing agents such as pmethylaminophenol, 1-phenyl-3- pyrazolidone, 4-phenylcatechol, 4-amino-5-methyl resorcinol, 2-amino-5-methyl resorcinol, pyrogallol monocarbonate and 1-phenyl-4,4-dimethyl-3-pyrazolidone when substituted for the present auxiliary hydroquinone developing agents.

The invention has been described in considerable detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A photographic element comprising a support having coated thereon three superposed dye image-forming units in layers capable of recording red, green and blue in said image-forming unit recording blue light being about .01 to .1 mil in thickness and containing about 25 to 250 mg. of gelatin per square foot.

2. A photographic element as described in claim 1 wherein the substantially colorless and substantially waterinsoluble hydroquinone is positioned in an overcoat layer on the emulsion side of the photographic element.

3. A photographic element as described in claim 1 wherein the substantially colorless and substantially waterinsoluble hydroquinone is selected from the group consisting of phenylhydroquinone, 2'-hydroxyphenylhydroquinone, phenoxyhydroquinone, 4-methylphenylhydroquinone, 1,4-dihydroxynaphthalene, 2-(4-aminophenethyl)-5-bromohydroquinone,

2- (4-aminophenethyl -5 -methylhydroquinone, 4'-aminophenethylhydroquinone, 2,S-dimethoxyhydroquinone, 2,5-dibutoxyhydroquinone, m-xylohydroquinone, bromohydroquinone, 3,6-dichlorohydroquinone, Z-dimethylaminoethyltoluhydroquinone, 2-cyclohexylhydroquinone, sec.-butylhydroquinone, 2,5-dichlorohydroquinone, 2,5-diisopropylhydroquinone,

2,5-diiodohydroquinone,

15 3-chlorotoluhydroquinone, tetrachlorohydroquinone, 2,S-diphenylhydroquinone, 2,S-diresorcylhydroquinone, 2,5-dioctylhydroquinone, and dodecylhydroquinone.

(e) a gelatino-silver bromoiodide emulsion layer sensitized to record green light;

(f) a gelatin interlayer;

(g) a layer about .01 to .1 mil in thickness containing about 25 to 250 mg. per square foot of gelatin and the yellow dye developer, 1-phenyl-3-N-n-hexylcarboxamido 4 [p-(Z,5-dihydroxyphenethyl)phenylazo]-S-pyrazolone;

(h) a gelatino-silver bromoiodide emulsion layer inherently sensitive to record blue light; and

(i) an overcoat gelatin layer containing about to 100 mg. per square foot of 4'-methylphenylhydroquinone;

said gelatin interlayers (c) and (f) being about A: to 3 times as thick and containing about 2 to 6 times as much gelatin as said layer (g) containing said yellow dye developer.

7. The process for preparing multicolor photographic diffusion transfer dye developer images which comprises treating an exposed photographic element as described in claim 1 with an alkaline liquid, developing latent images in the regions of exposure of the silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise in register to a dye developer reception layer.

8. The process for preparing multicolor photographic diffusion transfer dye developer images as described in claim 7 wherein the processing is carried out in the pres- 16 ence of an onium compound diffusible in the alkaline liquid.

9. The process for preparing multicolor photographic diffusion transfer dye developer images as described in claim 7 wherein the alkaline liquid contains a heterocyclic quaternary ammonium compound capable of forming a diifusible methylene base in said alkaline liquid and having the formula wherein:

(a) n is an integer of 0 to 1,

(b) Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus,

(c) X is an anion,

(d) R is selected from the group consisting of an alkyl radical, an aryl radical and an aralkyl radical, and

(e) R and R are each selected from the group consisting of a hydrogen atom and a lower alkyl radical.

10. The process for preparing multicolor photographic diffusion transfer dye developer images which comprises treating an exposed photographic element as described in claim 6 with an aqueous alkaline liquid, developing latent images in the regions of exposure of the silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise to the surface of said photographic element, and transferring the resulting diffused images from said undeveloped regions in register to a dye developer receiving sheet superposed on said photographic element.

11. The process for preparing multicolor photographic diffusion transfer dye developer images as described in claim 10 wherein the aqueous alkaline liquid contains about 2% to 15% of l-benzyl-Z-picolinium bromide based on the weight of said aqueous alkaline liquid.

References Cited UNITED STATES PATENTS 2,983,606 5/1961 Rogers 963 3,077,400 2/1963 Rogers et a1. 963 3,146,102 8/1964 Weyerts et a1. 963

FOREIGN PATENTS 221,880 5/1959 Australia.

NORMAN G. TORCHIN, Primary Examiner.

A. T. SURO PICO, Assistant Examiner.

Images