US2409959A

US2409959A - Method of forming images of dichroic materials

Info

Publication number: US2409959A
Application number: US536030A
Authority: US
Inventors: William H Ryan; Barnes Arthur; Helen P Husek
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1944-05-17
Filing date: 1944-05-17
Publication date: 1946-10-22
Anticipated expiration: 1963-10-22

Description

Oct. 22, 1946. Iw, H, RYAN ET AL 2,409,959

JMAGE 0F su vee W/LL/MH. RYA/v A ARTHUR BAM/sand HELE/v Haal-:K f

QQ i tormgy Patented Oct. 22, 1945 METHOD F FORMING IMAGES OF DICHROIC MATERIALS William H. Ryan, Cambridge, Arthur Barnes, Waltham, and Helen P. Husek, Allston, Mass., assignors to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Application May 17, 1944, Serial No. 536,030

This invention relates to methods of forming images of dichroic materials, i. e., materials such as iodine, which plane polarize light when supported by, or suspended in, a suitable molecularly oriented plastic carrier, and to methods of producing said image in such carriers.

It is Vone object of the present invention to provide a novel method of producing images in polarized light, which images are known as vectographs and, more specifically, to provide vectographs which are reproductions of photographic images.

Another object of the invention is to provide a novel method of so transforming an image produced by exposing and developing a photosensitive emulsion as to produce a corresponding image in a dichroic material. y

` It is a further object of the invention to provide a novel method of chemically transforminga latent image, obtained by exposing a silver halide emulsion, to an image in iodine.

Further objects of the invention are the provision of a method of conventionally exposing a silver halide emulsion and thereafter subjecting said emulsion to a plurality of novel chemical transformations whereby iodine replaces the exposed silver halide particles of the original emulsion; the provision of a novel method of eiecting the desired chemicaltransformation from a photosensitized silver halide to iodine whereby the iodine image is sharply and clearly defined; the provision of an oriented sheet of plastic, such as polyvinyl alcohol, adapted to render an iodine stain. dichroic, surfaced with or containing a conventional silver halide emulsion, as for example of gelatin, or acting as the protective colloid for the silver halide, and the use thereof in carrying out the novel transformation of the invention to obtain a corresponding dichroic image; and the provision of a novel method of obtaining an iodine image in an unoriented material and of transforming said image to a molecularly oriented plastic carrier, as by a Surfaceto-surface contact, for the purpose of producing a corresponding dichroic image in said carrier.

Other objects of the invention will in part -be obvious and will in part appear hereinafter.

The invention, accordingly,comprises the sev- Veral steps and relationof one of said steps with respect to each of the others, `which are exemplified in the following disclosure and the scope of the application of which will ybe indicated in the claims. V f g For a fuller understanding of the nature and objectsof the invention, Vreference should be 28 Claims. (Cl. 95-5) 2 Y had to the following detailed description taken in connection with the accompanying drawing wherein Fig. l is a schematic view of a photographic element used with the invention after exposure and development thereof to effect image formation therein; and

Fig. 2 is a schematic view of the element shown in Fig. 1 after further processing thereof.

This invention contemplates the production of a predetermined image, or the like, by the transformation of a portion of a layer of non-polarizing material to a polarizing area, whereby said image is obtained in polarized light. In accordance with the invention an emulsion of a photosensitive material, such as a silver halide, is exposed and then developed and converted in a novel manner to form the desired image in iodine.

In one method comprehended by the invention, the exposed silver halide is so developed as to form in situ with the silver image a secondary image, which secondary image is then subjected to a novel chemical transformation and converted thereby into the corresponding iodine image. At some stage in the transformation prior to the formation of the iodine image the silver and silver compounds arev preferably removed.

In a preferred form of the invention, the silver halide emulsion consists of a sheet or layer of oriented plastic, which plastic is of such character that iodine is adapted to produce therein a light-polarizing stain. In another form of the invention the oriented plastic sheet, instead of forming part of the photosensitive emulsion from which the silver image is obtained, may constitute a base or a support for a conventional sillver halide emulsion, as for example of gelatin,

the iodine which forms the image migrating` from the gelatin into the plastic sheet. In still another form/of the invention, the silver halide emulsion may comprise a suspension of the silver halide in a mixture of gelatin and polyvinyl alcohol. It is also to be understood that other transformations of a latent image formed by exposure of a silver halide emulsion to an iodine image, are Within the 'scope of the invention, as for example, a photosensitized conventional paper print may have the latent image converted to an iodine image, in accordance With the processes of the invention, and the iodine image may then be imprinted by a suitable transfer process on a sheet of oriented plastic to produce in said sheet a, dichroic image.

polyvinyl alcohol, partially hydrolyzed polyvinylV acetals and polyvinyl alcohol esters, and regenerated cellulose. Of the materials falling within this class the preferred material is polyvinyl alcohol and images formed in properlyl prepared sheets of that material possess the highest dichroism and hence are more suitable in the production of dichroic images.

In order to obtain the best results with respect to dichroism in the imagesof vthe present invention, at least one layer of molecules of the plastic carrier should rst be oriented to substantial parallelism. flhis Amay be conveniently accomplished by softening the sheet, as 'for example by subjecting to heat and then stretching or extending the sheet until suitable orientation'of the molecules has been obtained. 4'In the case of polyvinyl alcohol, a sheet formed by casting may be placed in satisfactory condition for `the formation ofy dichroic imagesftherein by subjecting lthe sheet to mechanical stress, as for example, by stretching in a uniform direction until the molecules therein are sufficiently oriented. A stretch of from two to six times the original length of the sheet produces vgood result. Alternatively, the surface molecules 'of a .sheet of polyvinyl alcohol may be oriented, as by applicationof linear `frictional force thereto, 4without orienting the molecules throughout the remainder of the sheet. l

Where the entire transformation of a latent silverhalide image to an iodine image is effected in -a molecularly oriented plastic carrier, the .carriervvis preferably one which maintains its orientation and is stable throughout the steps comprising the jnovel process of the invention. Polyvinyl alcohol, the preferred material for the plastic carrier, is stable in, and is permeable Yby,thersolutions which kconvert and transform -thef'latent silver halide image to the dichroic Polyvinyl alcohol is also relatiyely insoluble in said solutions so that a sharp dichroic image is obtained despite the several image of iodine.

transformations which constitute the. novel 'process of the invention.` v

The plastic carrier in any'of the processes comprehened by the present invention `may be supported on al sheet of ya transparent plastic,`

`as for'example `a cellulosic plastic, such as cellulose acetaterand cellulose nitrate, or-a vinyl compound, such Yas the vinyl acetals, vinyl ace; -tate, vinyl chloride'the vinyl acetate-vinyl clilo- Vride, copolymers, or a condensation type super- ,polymen 'such vas Ya polyamide or nylon type plastic. Cellulose acetate is a preferred material for the support and to'for'm the `most satisfactory I'materialfor thevdichroic image there is bonded to at leastone faceof a sheet of said acetate, a sheet of -molecularly oriented polyvinyl `alcohol, having ahydroxyl content, preferablyin `excessof 50%, said polyvinyl alcohol sheet being uniformly oriented throughout its entire thickness. l

iThfegfollowing description of` the invention is Agiven by way of example in connection with a `material'having'a silver` halide suspension in an oriented plastic Vcarrier on only one surface thereof whereby a single image in polarized light is obtained. It is to be expressly understood, however, that the process is equally applicable to the formation of dichroic images on a material having both of its faces molecularly oriented and ondary image in situ with said silver image.

constituting part of, and supporting on both of its faces, silver halide suspensions adapted to provide desired images. The images may be of the same object and may bear a predetermined relation to one another. For example, one may be the left eye image and the other the right eye image of a stereoscopic pair, and the directions of the molecular orientations of the plastic layers carrying said images may be at substantially right angles to one another so that an observer of the iodine images, provided with a pair of suitably oriented analyzers, may have only the left eye image rendered visible to his left eye and only the right eye image to his right eye, whereby the object is seen stereoscopically. a

In accordance with one method `of carrying out the present invention, a silver halide emulsionis exposed and is thereafter developed to produce a. silver image, the development being effected in a novel developing solution which gives, in addition to said silver image, an vinsoluble oxidation by-#product which. forms a sec- The oxidation by-product forming this secondary image is insoluble and stable, not only in the developer, but also in the bleach solution or solutions wherein, as a next step in the process, the silver is preferably transformed to a soluble compound and then removed by dissolution in a suitable solvent. This is preferably performed in a single solution but may be carried oui-fin two solutions. The oxidation'by-p-roduct forming the insoluble secondary image has ka sufficiently high oxidation potential to release iodine from an iodide in the presence of a suitable releasing medium, such as an 4acid` or other solvent for the secondary image, so that after the bleaching which removes the silver and the silver salts, the oxidation by-product is reacted with an viodide-in the presence ofsaid medium, releasing iodine. The released iodine replaces said product and forms the desired image. In instances wherein the iodine is formed inra gelatin layer coated on or supported by a molecularly oriented y plastic in /face'eto-face vContact therewith, the

AVis=required only if the carrier for the silver halide is I-an oriented fplastic, ire., if' the dichroic image is being formed directly .in the carrier for the photosensitive emulsion. If the carrier an unoriented material, such as a paperY print, from which the -iodine is to `be transferred to anoriented plastic surface or sheet, .the transfer of iodine to said oriented plastic can be effected Ywithoutl removing the reduction vproduct of the iodine-forming reaction. Y. A

It will now be apparent that the'selection'of ,'.the materials for carrying out the instant invention, such as the developer solution and the "bleach lammonium thiocyanate.

solution, mustbe made in the light of the properties of both of said solutions and that the selection of any one will render available a great numbei: of materialsforthe other. It' is only necessaryY that a selected developer give an insoluble secondary image having the required oxidation potential and thatthe bleach bath, or baths, be selected in relation to the oxidizing product of said developer as to bleach the silver image and, if desired, remove the silver salts without alecting the secondary image comprising said product. These conditions may be satisiied by a large numbery of developer solutions and bleaching baths. Although the reducing agent for converting the silver halide to silver and producing the secondary image of an insoluble oxidizing agent may constitute the only reactive ingredient of the developing solution, an accelerator may be incorporated in the developing solution, as well as a restrainer, provided that said reducing agent is selected to give an oxidation by-product which is insoluble in whichever of said materials is added to the developer solution. i

A suitable reducing agent for the novel developing step of the invention is p-dimethylaminophenol, which reduces the exposed silver halide and gives an oxidation by-product that is insoluble in the developer and has a high enough potential to release iodine from an iodide. Other suitable reducing agents are pyrocatechin, toluhydroquinone, 4-4dihydroxy diphenyl, monochlorohydroquinone, dichlorohydroquinone, 2-5 dihydroxydiphenyl, acetyl-p-aminophenol, pbenzylaminophenol, and 3-4 dihydroxy diphenyl.

Each of these reducing agents is preferably usedy in a developing solutionA which is alkaline. To remove the silver and the silver salts without affecting the oxidation by-product, a preferred bleach for use in connection with all of the above specied developers consists of an aqueous solutiongof amixture of potassium ferricyanide and The potassium ferricyanide acts to transform the silver to a salt soluble in the ammonium thiocyanate. Other compounds known in the art for transforming the silver to soluble silver salts, such as sodium ferricyanide, may be used together with other known solvents for said salts, such as sodium and potasasium thiocyanate, provided that none of the compounds so formed or solutions therefor, react with or dissolve the secondary image. The compound for transforming the silver to a soluble silver salt is preferably used in the same solution with the solvent for said salt, providedthere is no undesirable interaction between said compound and said solvent.

The iodide solution wherein the iodine is released to form an iodine image preferably comprises potassium iodide and hydrochloric acid, lalthough other iodides, such as sodium or amthe novel developing step for obtaining the in- 4soluble secondary imageof the desired oxidizing potential is carried out by using in the developing solution a compound for developing the silver ,halide to give a silver image and a coupler which page with up, bi1-,product 0f ,the redueifigqf the silverlia'lide to` form the desired secondaryirnage.

A suitable developing solution for this purpose comprises para-amino-diethylaniline as the reducing agent for the silver halide, and orthocresol as the coupler. The print is then preferably bleached and the silver salts are removed 'and a suitable bleach for this purpose is an aqueous solution of a mixture of potassium ferri'cyanlde and potassium thiocyanate. The secondary image is then reacted with an iodide in thepresence of an acid to form the iodine image. In the practice of the above method, it is to be understood that the coupler may be contained in the silver halide emulsion.

It is also to be understood that the invention comprehends any process wherein a latent ime age, ,produced by the exposure of a silver halide, is transformed or'converted to, or causes the formation of, an image comprising a compound which releases iodine from an iodide in a Asolution containing a solvent for said compound such, lfor example, as an acid. v

The following examples ofthe novel process of the present invention are given for purposes of illustration, but it is to be expressly understood that the proportions, temperatures and times may beV varied within wide ranges and that the ingredients may also be varied, as specified hereinabove and as will now be apparent to those skilled in the art.

Example 1 p-Dmenihylaniinoplienolf-ff- 1/2` Sodium hydroxide do 1 Water c. c 100 VImmersion in the above solution for approximately one to two minutes gives good results and the developer is preferably maintained at approximately room temperature during this step of the process. The print is then washed and immersed for approximately one minute in a solution for bleaching the silver image and for removing the silver salts, which solution consists Potassium ferricyanide grams-- 3 Ammonium thiocyanate do 34 Water c.'c V200 VThe print is then washed and placed in an acid `solution of Ypotassium iodide consisting of Y c. c. `Potassium iodide, 10% solution 100 25 Hydrochloric acid, 2N solution Afor approximately 30 seconds.,`

l It is preferable to immerse the print in a nal ,fixing bath, which bath contains boric acid, to

stabilize the dichroic image. The fixing bath may also contain sodium sulfate to preventsoftening of the plastic sheets, potassium iodide to provide 'a control for the color of the image, and in some Iinstances a weak solutionof sodium thiosulfate.

70.' .Y Example 2 l f A layer or sheet of molecularly oriented polyvinyl alcohol containing, or supporting, a silver halide emulsion and mounted on a suitable sup- ,porting sheet ,of nelluloseacetata isexposedand 7 is' Jthenimmersedv in a' developing solutionconsigna-g:ofgV l Y. p-.Aminodiethylaniline hydrochlo- 'ride 1 grams 1 o-Cresoll. V do 0.5 Sodium hydroxide do 0.5 Water...l c. Q 100 l .After immersion in the above solution for yap- -pmximately one to two minutes, the print issubjected to the severalsteps of the process described in Example 1 `as following the ,developing .of the .latent image.

Example 3 v Themolecularly oriented polyvinylv alcohol layeror sheetof Examplevl is treated in the same way Yas rdisclosed in Example 1 except. that the silver image is bleached and thesilver salts are removed ina solution consisting of:

n l c. c. Potassium ferricyanide, 10% solution 80 Sodium thiosulfate, 25% solution 20 7 'N Examples! |Ti'vhe method described in Example 1 is followed except -that .thedeveloping solution consists of:

-Pyrocatechin grams 3 Potassium bromide do 1/2 Sodium thiosulfate, 20% solution c. c 80 Water c. 100

Sodium hydroxide, 15% solution c. c 12 Example 5 'flhejmethod described in Example l is followed exceptpthat the developingsolution consists of:

Toluhydroquinone grams 1/2 Potassium bromide do V27,-,

Sodium hydroxide k do 1 Water 1 c. c 100 gramme 6 yThe method described in Example 1 is followed :except that the developing solution consists of:

f lIt .will'lbenoted thatin every example Agiven above; vit is contemplated that the iodine image will be formed in a sheet of a high polymer which iis-1molecularly oriented. It lis conceivable that the novel transformation ofy a latent silv'erhalid'e" image to an iodine image, inaccordance with the present invention, may be useful invconnection with other Vprocesses thanffthe formation' of Idi-V vclfiroic limages and, 'accordinglypit is` expressly v,understood that unless'the claims'so specify, they `are lnot limited to the formation of an iodine image in a 'carrier which 'is molecularlyforiente'd. VvByfway of understanding the heretofore de,- scribed practices', Figs. land 2'schematica1ly show a photographicelement during variousl stages of processing. The element shown in Figs. '1 rand 2comprises Aav suitable-:support lllffor-an `image-carrying,layer'il I. Fig. ll-portrays a photo- `graphic element which vvfhas! AVan image-carrying variables.

a conditionfollowing the .exposuregand development ofthe layerinaccordance withzthe'teachings Aof `.the invention to. provide V'an image-t2 therein comprising silverandan oxidizing agent. Fig. .2 discloses the element .after :further treatment, Aas by .the Vbleaching procedure heretofore set forth, to remove `.the silver and to leave lan image formed only of an oxidizing agent, `.the same ,being indicated by Ithe `reference vcharacter vFrom the foregoing description Yit will Pbe apparent .to those skilled in .the art thatif the layer .il .is a molecularly .oriented carrier, .treatment -thereofwith a suitable iodide solution kwill kreplace theimage .M formed ofthe oxidizing agent with iodine. In ,the eventV Ythat Vthe' layer Il Vis gelatin and thesupporti ismolecularly'oriented plastic, iodine released 'from -a'solution .of yan iodide `by the oxidizing agent. will form alightpolarizing image in iodine fin'the plasticsupport. Also, if the .layer fil represents .a conventional paper print Vin which an .image .M comprising an oxidizing agent haslbeen formed, it may be used in the .described transfer process to provide a light-polarizing image in molecularly oriented plastic material when brought into contact therewith and treated in the manner already set forth.

As has been previously stated, the foregoing description is illustrative only of-operative embodiments of the present invention. It must be emphasized that each step therein is a variable and that none of the ingredients, times, or proportions for any step or solution are critical except insofar as they may be made so .by the other The specic examples given comprise operative embodiments of the invention with which. excellent vresults have been obtained. However, considerable variation is possible in lvirtuallyaany degree thereof, and one or more solutions or steps can be ycompensated for in the other steps. It is, accordingly,` obvious that Lno set rules can be given and it would be difficult, if not impossible,` even toset outside limits on the ranges o-f variation.

It is to be understood that the term relatively water-insoluble as utilized in the claims vin reference to the carrier for the silver image refers to an insolubility such as will preventfwater solu- :tions from appreciably dissolving said-carrier in ing sense. Slt is also to 'be understood thatthe following claims are intended to cover all the generic and specicufeatures rof the invention herein dethe time in which the reactions transforming-the silver halide image to the -iodine image take scribedand5all statements of the 'scope of the inysaid to fall therebetween."v 'l'fWhjatjs claimed is: j" `vif'flhe method of producinga dichroic image, k'which comprises ph'otfoeexposing [a silver vhalide "suspensionto produce' a latentA image, .developving saidjlatent image to form .arrimage compris- 4V`ing La, water-insoluble, oxidizing yagent having an VA'xidation potentialsuiiiciently 'high Ito, release 1o'dine' from kan iodide, reacting the image'comiprisingfsagid Aoxidizing agent with an iodide ,in the presence fof 'ajsolvent forjsaidoxidizing agent vention'wnicn as a matter Aof.,1angia'ge',l.rnighf, be

and not 'in a limitl iodine `from the iodide, 'and having present at some stage during the release of said iodine, in a position to receive said iodine, a layer of molecularly oriented high polymer which. forms a di chroic sorption complex with iodine.

2. The method of producing a dichroic image, which comprises photo-exposing a silvel1 halide suspension to produce a latent image, developing said latent image to form an image comprising silver and a water-insoluble oxidizing agent having an oxidation potential sufficiently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, reacting the'image comprising said oxidizing agent with an iodide in the presence of a solvent for said oxidizing agent which dissolves the latter and causes it to release iodine from the iodide, and having present at some stage during the release of said iodine, in ai position to receive said iodine, a layer of molecularly oriented high polymer which forms a dichroic sorption complex with iodine.

3. The method of producing a dichroic image, which comprises photo-exposing a silver halide suspension to produce a latent image, developing said latent image to form an image comprising silver and a water-insoluble oxidizing agent having an oxidation potential suiiiciently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in a solution in which said oxidizing agent is relatively insoluble, reacting the image comprising said oxidizing agent with an iodide in the presence of av solvent for said oxidizing agent which dissolves the latter and causes it to release iodine from the iodide, and having present at some stage during the release of said iodine,in a position to receive said iodine. a layer of molecularly oriented high polymer` which forms a dichroic sorption complex with iodine. d

4. The method of producing a dichroic image, which comprises photo-exposing a silver halide suspension to produce a latent image, transforming said latent imageby reaction with a developer and a coupler to an image comprising silver and a water-insoluble oxidizing agent having an oxidation potential suiciently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizingY agent, removing the silver compounds from said carrier in a solution in which said oxidizing agent is relatively insoluble, reacting the image comprising said oxidizingagent with an ing agent which dissolves the latter and causes it to releaseiodine from the iodide, and having present at some stage during the release of said iodine, in a position to receive said iodine,a layer of molecularly oriented high polymer which forms a dichroic sorption complex with iodine.

5. The method of producing a dichroic image, which comprises photo-exposing a silver halide suspension to produce a latent image, developing said latent image to form an image comprising a water-insoluble oxidizing agent having an oxidation potential sufficiently high to release iodine from an iodine, reacting theimage comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released, and having present at some stage during the release of said iodine, in a position to receive said iodine, a layer of moleclularly oriented high polymer which. forms a dichroic sorption complex with iodine. ,Y ,Y

` 6. The method of producingV a dichroic image, which comprises photo-exposing a silver halide suspension to produce a latent image, developing said latent image 'to form an image comprising silver and a water-insoluble oxidizing agent lhaving an oxidation potential sufciently high torelease iodine fromA aniodide, reacting said Aimage with a bleaching agent for silver which is vinert to said oxidizing agent, reacting the image `comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released, and having present `at some stage during the release oi said iodine, in a position to receive said iodine, a layer of molecularly oriented high polymer which forms a diohroic sorption complex with iodine.

7. The method of producing a dichroic image, which comprises photo-exposing a silver halide suspension to produce a latent image, developing said latent image to form an image comprising silver and a water-insoluble oxidizing agent having an oxidation potentialsuoiently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from'said carrier in a solution in which said oxidizing agent is relatively insoluble, reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released, and having present at some stage during the release of said iodine, in aposition to receive said iodine, a layer.of,molecular1y oriented high polymer which forms a Vdchroic sorption complex with iodine. i i

.8. The method of producing a dichroic image, which comprises photo-exposing a Vsilver halide suspension to produceY a latent image, transformi ing said latent image by reaction with adeveloper and a coupler to an image comprising silver and a water-insoluble oxidizing agent having an oxidation potential suiciently `high to release iodine froman iodide, reacting said image with ableaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in a solution in which said oxidizing agent is relatively insoluble, reacting the image comprisingsaid'-oxidizing agent with an iodide in the presenceAof-an acid whereby iodine is released, and having present at some stage during the release of said iodine, in a' position to receive said iodine, a .layerof molecularly oriented high polymer which forms a dichroic sorption complex with iodine.

9. The method of producing a dichroicY image, which comprises providing a photosensitive silver halide suspension in a relatively water-insoluble carrier comprising at least a layer of a permeable molecularly oriented highV polymer having an affinity for iodine and adapted to form a dichroic sorption complex therewith, said layer supporting said silver halide suspension, photo-exposing the silver halide to produce a latent image, developing said latent image to form an image cornprising silver vand a water-insoluble oxidizing y agent having an oxidation potential sufficiently high to release iodine from an iodide, reacting Vsaid image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in asolution in which said oxidizing agent is relatively insoluble, and reacting the image comprising said oxidizing ,agent with an iodide in the presence of `l l an acid whereby iodine is released to form the image in iodine.

*10. 'I he method of producing a dichroic image, which comprises providing a photosensitive silver halide suspension in a relatively water-insoluble carrier comprising at least a layer of a permeable molecularly oriented high polymer having an afli'nity for iodine and adapted to form a dichroic sorption complex therewith, said layer supporti-ng saidsilver halide suspension, photo-exposing the silver halide toproduce a latent image, transforming vsaid latent image by reaction with a developer and" a coupler to an image comprising silver and a water-insoluble oxidizing-agent having-an oxidation potential sufficiently high to release iodine from an iodide, reactingv said image with a bleaching agent for silver which is inert tosaid oxidizing agent, removing the silver compounds irom said carrier in a solution in which said oxidizing agent is relatively insoluble, and reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodiney is released to form the image in iodine.

Y 1l. The method of producing a dichroic image, which comprises providing a photosensitive silver halide suspension in a carrier' having at least the layer which supports said suspension formed of a molecularly orientedpolyvinyl alcohol, photoexposing the silver halide to produce a latent image, developing said latent image-to form an image comprising silver and a Water-insoluble oxidizingagent having an oxidation potential suiciently'high tol release iodine from an iodide, reacting said image with Va bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in asolution in which, said oxidizing agent is relatively insoluble, and reactingfthe image comprising said oxidizing agent with V4an iodide in the presence of an acid whereby iodine is released to form the image in iodine. Y l

l2.` The method of producing` a dichroic image, which comprises providing a photosensitive' silver halide suspension in a carrier having at least the layer whichsupports said suspension formed or a molecularly oriented polyvinyl 4 alcohol, photo-exposing the silver halide to producev a latent image, transforming said latent image by reaction with a developer and a coupler to an image comprising silver and a water-insoluble' oxidizing agent having an oxidation potential suiiiciently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said 'carrier in a solution in which said oxidizing agent is relatively insoluble, and reacting the image comprising said' oxidizing agent with an iodidev in the presence of an acid whereby iodine is released to form the image in iodine. Y

1,3'. The method of producing a dichroic image, which comprises providing a photosensitive vsilver halide suspension in a permeable relatively waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent h image to form an image ,comprisingV a Waterinsoluble oxidizing agent having an oxidation Apotential suiiciently high to releaseiodine froman iodide, reacting the image comprising said oxidizing agent with an iodide in' the presence of an .acidfwhereby iodine is released toI form the image in iodina and bringing into face-to-face contact with `said carrier a transparent molecularly orientedlngh polymer adapted t form ai dfhroic sorption complex with iodinev and f having a greater anity for iodine than said carrier.

14. The method of producing a dichroic image, which comprises providing aphotosensitive silver halide suspension in a permeable relatively Waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image to form an image comprising 'silverA andA a Water-insoluble oxidizing agent having an-o-xida-- tion potential sufcently highv to release iodine from an iodide, reacting said image With a bleaching agent for silver-which is inert to said oxidizing agent, reacting the image comprising said oxidizing agent with: an iodide in the presence of an. acid whereby iodine is vreleased to form the image in iodine, and bringing into face-to-fface contact With said carrier a transparent molecularly oriented high polymer adapted to formga dichroic sorption complex with. iodine and having a greater ailinity for iodine than said carrier. y

l5. The method of producing a'dvichroicimage; which comprises providing a photosensitive silver halide suspension in avpermeable relatively waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, developing sai'd latent image to form animage comprising a- Wat-erinsoluble oxidizing agent havingl an'oxidaton potential suiciently high to release iodine from: an iodide, reacting the image comprising said oxidizing agent with an idodide in the presence of an acid whereby iodineisV .released to formv the image in iodine, and bringing into face-to-face kcontact with said carrier a molecularly oriented polyvinyl alcohol. A v

16. The method of producing a dichroic image, which comprises providing Aa photosensitive silver halide suspension in a permeable relatively waterinsoluble carrier, photo-exposing thesiiver halide to produce a latent image, developing said latent image to forman image comprising silverand a water-insoluble oxidizingagent having an oxidation potential sufficiently high to release iodine from an iodide, reacting said image with aY bleaching agent for silver which is inert Yto said oxidizing agent, reacting the image comprising said oxidizing` agent with an iodide ingthe presence of an acid whereby iodine isr released to form the image in iodine, and bringing intofface-tog face contact` with said Vcarrier a molecularly oriented polyvinyl alcohol. y. y H y 17. The methodv of producing a. dichroic image, which comprises providing a photosensitive silver halide suspension in a permeable relatively Waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, developing saidlatent image to forman ,image comprising 'a Waterinsoluble oxidizing agent having an loxidation potential suiiiciently high to release iodine from an iodide, immersing said carrier nan iodide, and

bringing said carrier into `acetofa0e Contact vwith a transparent molecularly oriented high polymer containing an acid and adapted to 'form a dichroic sorption complex with iodine. l

1 8. The method of producing a dichroic image, which comprises providing a photosensitive silver halide suspension in a permeable relatively waterinsol-u'ble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image to form an image comprising silver and a water-insoluble oxidizing vagent having an oxidatio'n suiii'ciently high to release iodine from 'an iodide, reacting said image with `a bleaching agent for silver which is inert to said oxidizingV agent, immersing said carrier in an iodide, and" bringing said carrier into face-to-face Contact with' a transparent molecularly oriented high polymer containing an acid and adapted to form a dichroic sorption complex with iodine.

19. The method of producing a dichroic image', which comprises providing a photosensitive silver halide suspension in a permeable relatively waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image to form an image comprising a waterinsoluble oxidizing agent having an oxidation potential sufficiently high to release iodine from an iodide, immersing said carrier in an iodide, and bringing said carrier into face-to-face contact with a molecularly oriented polyvinyl alcohol containing an acid.

20. The method of producing a dichoric image, which comprises providing a photosensitive silver halide suspension in a permeable relatively waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image to form an image comprising silver and a water-insoluble oxidizing agent having an oxidation potential suiliciently high to release iodine from an iodide, reacting said image with a bleaching agent ior silver which is inert to said oxidizing agent, immersing said carrier in an iodide, and bringing said carrier into face-toface contact with a molecularly oriented polyvinyl 'alcohol containing an acid.

21. The method of producing an iodine image, which comprises providing a photosensitive silver halide suspension in a permeable relatively water-insoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image in an alkaline solution comprising monochlorohydroquinone to form an image comprising silver and an oxidizing agent insoluble in said solution and having an oxidation potential sufficiently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in a solution in which said oxidizing agent is relatively insoluble, and reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released to form the image in iodine.

22. The method of producing an iodineimage, which comprises providing a photosensitive silver halide suspension in a permeable relatively water-insoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image in an alkaline solution comprising p-dimethylaminophenol to form an image comprising silver and an oxidizing agent insoluble in said solution and having an oxidation potential suincient high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in a solution in which said oxidizing agent is relatively insoluble, and reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released to form the image in iodine.

23. The method of producing an iodine image, Which comprises providing a photosensitive silver halide suspension in a permeable relatively waterl 14 reacting said image with a bleaching agent yfrom the class consisting of sodium ferricyanide and potassium ferricyanide, removing the silver compounds from said carrier in a solution of a v'compound from the class consisting of ammonium thiocyanate, sodium thiocyanate and potassium thiocyanate, and reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released to form th'e image in iodine. A "24. The method of producing an iodine image, which comprises providing a photosensitive silver halide suspension in a permeable relatively Water-insoluble carrier, photo-exposing the silver halide to produce a latent image, developing said latent image in an alkaline solution comprising monochlorohydroquinone to form an image comprising silver and an oxidizing agent insoluble in said solution and having an oxidation potential suiciently high to release iodine from an iodide, reacting said image with a bleaching agent from the class consisting of sodium ferricyanide and potassium ferricyanide, removing the silver compounds from said carrier in a solution of a compound from the class consisting of ammonium thiocyanate, sodium thiocyanate and potassium thiocyanate, and reacting the image comprising said oxidizing agent with an iodide in the presence Of an acid whereby iodine is released to form the image in iodine.

25. The method of producing an iodine image, which comprises providing a photosensitive silver halide suspension in a permeable relatively waterinsoluble carrier, photo-exposing the silver halide to produce a latent image, transforming said latent image by reaction with p-amino-diethylaniline and o-cresol to an image comprising silver and a water-insoluble oxidizing agenthaving an oxidation potential suiiiciently high to release iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, removing the silver compounds from said carrier in a solution in which said oxidizing agent is relatively insoluble, and reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released to form the image in iodine.

26. The method of producing an iodine image, which comprises providing a photosensitive silver halide suspension in a permeable relatively water-insoluble carrier, photo-exposing the silver halide to produce a latent image, transforming said latent image by reaction with p-amino-diethylaniline and o-cresol to an image comprising silver and a water-insoluble oxidizing agent having an oxidation potential suciently high to release iodine from an iodide, reacting said image with a soluble of potassium ferricyanide and potassium thiocyanate to remove the silver and silver salts, and reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released to form the image in iodine.

27. The method of forming a dichroic image which vcomprises photoexposing a permeable relatively water-insoluble carrier which is sensitized with silver halide to form a latent image therein, developing said latent image to form an image comprising a water-insoluble oxidizing agent having an oxidation potential suflicient to effect the release of iodine from an iodide, reacting the image comprising said oxidizing agent with an iodide in the presence of an acid whereby iodine is released, and causing the iodine to migrate into a, molecularly oriented polymeric plastic to form inthe oriented plastic a dichroc sorption complex in iodine.

28. The method of forming a dichroic image which comprisesphotoexposing a permeable relatively Water-insoluble carrier which is sensitized with silver halide to form a latent image therein, developing said latent image to form an image comprising silver and a Water-insoluble oxidizing agent having an oxidation potential sufcient to effect the release of iodine from an iodide, reacting said image with a bleaching agent for silver which is inert to said oxidizing agent, reacting the image comprising said oxidizing agent with an iodide in the presence o an acid whereby iodine is released, and causing the iodine to migrate into a molecularly oriented polymeric plastic to form in the oriented plastic -a dichoric sorption complex in iodine.

WILLIAM H. RYAN. ARTHUR BARNES. HELEN P. I-IUSEK`