US2698244A

US2698244A - Photographic transfer process utilizing a primary color developer for producing a colored photographic transfer image

Info

Publication number: US2698244A
Application number: US391310A
Authority: US
Inventors: Edwin H Land
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1946-10-08
Filing date: 1953-11-10
Publication date: 1954-12-28
Anticipated expiration: 1971-12-28

Description

Dec. 28, 1954 E. H. LAND 2,598,244

' PHOTOGRAPHIC'TRANSFER PROCESS UTILIZING A PRIMARY COLOR DEVELOPER FOR PRODUCING A COLORED PHOTOGRAPHIC TRANSFER IMAGE Original Filed Oct. 8, 1946 Developable Phofosensifive Maieriol Phoiosensifive Layer Developed Phoiosensifive Mawrial [00 I010 (me [7 Developer Solufion Developer Solufion l4 Reaci'ed Developer 1 FIG. 4

Phoiosensiiive Layer lmage Carrying Layer Base 36 30 w v I Phoi'osensifiva Layer 6 Coa'hng L'ayer Image Carrying Layer 34 34 Backing Layer FIG. .7 \q hoi'osensifive Layer Image Carrying Layer 6 PHOTOGRAPHIC TRANSFER {PRGGESS UTILIZING,

A PRIMARYLCQLOR DEVELOPER FUR PRODUC- IN G A; CQLGRED .PHQTOGRAPHIC .TR'ANSFER.

IMAGE Edwin H. Land; Cambridge, Mass assignor to Polaroid Corporation, Cambridge, Mass, a. corporation of Delaware.

Original application October .8, 1946, SerialNo. 702,039, now Patent No. 2,661,293, datedfDecemher, 1, 1953. Divided andjthisappli'c'atidn November v1 ll, 1953, Serial No; 391,31il

This inventionzrelates to photography and, more particularly; to "novelphotographic,processes;

Thisapplication is a"divisionxof my copending application serial No. 702,039, filed October 8, ,1946 for Process forrProducing a' Colored Photographic Image by- Means.

off'EXh'austion of Developer, now.-Patent.No. 2,661,293, which, .in turn, is .a continuation-in-part of my applicationcSerialtNo.1 53.9,550," filed.;June,9, 1944 for Photographic Product,,,Process and Apparatus (abandoned and replaced by. application Serial No, 64,870, filed 'Decem her-r11, 1948, ,now issuedfas Patent No. 2,543,181 on Eebruary.27, 1951)1 It is aprincip'al object of.jthis invention to provide an improved photographic process wherein .a .visible positive image. isobtained from a photosensitive layer. containing a latent. or. developed f negative... image, by, utilizing. the differential effect-created bysaid photosensitive layer on a;. substance, usable. in forming said. visible positive image, .to. control .the; amount of'saidsubstance which is availablefor creating said positive image.

Anotherob'ject of .thepresentinvention is to provide a photographicqprocess whereina photosensitivelayer containingga latent or developed'negative image ispermeated with a substance having-the capabilityof entering into a reaction which produces avisibleeifect on another layer,

said .substance...is reacted 'with amaterial in said photo-, sensrtivelayento selectively, make. portions of. said sub--v stance incapableof'creating said .visible effect, and the remainder otsaidlsubstance. is used'to create. said visible effect on..said other layer, said. visible elfect, due to its selective creation, forming a positive image.

Anotherobject-of the :presentinvention is to assure, in processes of theabove type, a. substantially :complete reaction-of said "substance with said-material prior-to the creation of said. visible: effect;

Another'objectof-theinvention isto provide a novel photographictprocesswherein adeveloper is reacted with I at-layerof'photosensitive. material containing a latent negative image to. causes development ofsaid latent negative image and the portions of sald developer which are. not reacted, by said photosensitive -material during said developmenbreactlon-areutilized in forming a .posi-- tive image of said latentnegative'image in'or on another layer.

Another object of the'inventionisto provide a-positive' image+forming reaction in a;: process of the: above type .-wherein ,said unreacted portionsi of; said developer are utilized to form: a=dye:cons.tituting=a positive-- image.

Anothenobjecbof'tthe inventioir is to provide a positive image-forming reaction ina process of: theabove type whereinrsaid -developer:is a.primaryzonself-coupling color developer; andnwherein-r saidr-unreacted? portions of' the developer are utilized to form a dye constituting a'posi-- tive images Anotherrobject otither'invention is to improve the contrast of a:positiverimageaproduced.in a-process of the type .describedmaboveabywpreventingi-migration of reactedv portions-of said developeriromsaidaphotosensitive layer torsaid. other :layer.

' therr-objectsrof the inventionkzwilliin part be obvious and will.zin'part'iappear"hereinafter.

The invention: accordinglycomprises: the process involvinglxtherseveralisteps andthe relation and ord i' f one or moreofsuch' steps twith -respect toeach of the others which are" exemplified in-the following; detailed disclosure, and the scope of the'application of which; will be indicated in the claims;

For a fuller understanding ofathe nature-and yobjects;

of the invention, reference'should be had to the accompanying drawing wherein:

Figures 1 through 4 are diagrammaticrepresentations composite photographic: film "unit "showing one physical I embodiment 'of they invention;

Fig. 6 is a; diagrammaticcross-sectional-1 view of; a composite photographic film unit showing another physi; cal embodiment of the invention; and

Fig. 7 is adiagrammatic cross-sectional1view.of'a;-c0mposite photographic film unitl "showing; stillfanother physi;

cal embodiment of the invention.

In general this invention ,relates ,to novel photographicprocesses and produces for the production of afiXQdjstable positive ge a late t r;. ..ve .op. dfncs. t v a e.

containedina photosensitive-layer, thje positivegimage being formed in ,oron another layer hereinafter, referred to as an image-carryinglayer.

A rcal image of any object is a visiblelikenessor reproduction oftthat object. Photographically, an image may be recorded in a photosensitivelayerbytransform?v ing said layer, which isuoriginallysubstantially,homo, geneous throughout its volumetto aqlayer, suchthat a,

chemical characteristic thereofih'as animagewise; varia-. tion throughout the, Im gearea, the-,variationbeinga;

function of'thebrightness aspects of theoriginal subject image. The resultingrecord image maybe a,;real image, k

1. e., a visible .image, ,or, a, latent image,-.,i.v e., an ,image which, while not visible per se, has the capacity-upon;

suitable chemical ,treatment to producc a visible. image.

The, term record 'imageif' when, used here in its .,photo-.. graphic sense, may be characterized as arecord of the,

brightness aspects of j any predetermined 1 subject matter such-.as a person, object onrealimage, therecord being; in the form of Ta layer of material of predetermined small, thickness having throughout its image, area animagewise variation of aochemicalcharacteristic. of thelayer, thischemical characteristic;being. capable. of: producing a visible contrast either by; virtue, of :impartingdiiferent optical characteristics .per'sc topsaid layer. or by making possible the differential chemicaltreatmentof said layer whereby dilferential optical characteristics .are imparted to said. layer.

This invention. relatesto the use;of such a record image in a photosensitivetlayer for forming another image on an .image-carryinglayer, said other? image being reversed: in the positive-negative sense with respect to sa d record image.

In its preferred aspect theprocess. involves the production -onan image-carrylng; layer of a, positive image of a record negative image-by permeating the; layer containing." said negative image wi-tlra uniforrn quantity ofr asub-, stance-in solution selectively utilizing; the: diiierentialv chemicalcharacteristic ot said ;layer;to produce an effect.

on said uniformly permeated-substance, said effect being: a function' of the:irnagewise variation of; saidchemical characteristic; transferring unaffected portions; of saidsubstance; to; said; image carrying layer and-utilizing said unaifected-r portions to create a varying visible effect which, givesa;positive image ofisa d negative image.

The creation of the .visible elfecton' the image-carrying layer-may 13611116 resultof thecreation of acolor.

The first step.ofithe:preferred processis to permeate'a uniform quantity of-a liquid compositlon 1nto the photosensitive layer containing a record image comprising a.

latent or-developed negativeuimage; The-liquidicomp'osition preferably 1 comprises 7 a I solution ofa react ve. substance. The; latentror develop,ed ?negat1ve. -image 1n the photosensitivelayerpreferablyt comprises a photosensitive material having an imagewise distribution which varies as a direct function of the exposure creating said latent or developed negative image.

The amount of reactive substance permeating a unit area of the photosensitive layer is substantially uniform throughout an area thereof at least coextensive with said negative image and is preferably such that it will be substantially completely reacted by the portion of said photosensitive layer containing a highest concentration of said imagewise distributed material.

This reactive substance in the liquid composition is one having the capability of entering into a reaction with said material in said photosensitive layer and also of entering into a reaction which produces a visible effect on said image-carrying layer.

In the next step of the process, the reactive substance is reacted with the material in the photosensitive layer and portions of said substance are rendered incapable of producing a visible effect as the result of this reaction. The extent of reaction between the substance and the material in the photosensitive layer preferably varies, from point to point thereof, as a function of the point-to-point degree of exposure creating the negative image. There thus remains a distribution of unreacted substance whose capability of creating a visible effect varies in amount from point to point.

As another step of the process, the remainder of the reactive substance, i. e., that portion thereof which did not react with the material in the photosensitive layer,

is thereafter transferred to said image-carrying layer from said photosensitive layer by superimposing one of said layers on the other of said layers, the superimposing being sufiiciently intimate to permit the migration of said unreacted portions of said substance without any substantial degree of dispersion. The transferred unreacted portions of said substance are then utilized for creating a visible effect on said image-carrying layer. This visible effect preferably comprises the creation of a color and varies from point to point in accordance with the distribution of the unreacted substance. Due to the selective visible effect, i. e., color created, there is formed a positive image of said negative image on said image-carrying layer.

Referring now to Figs. 1 through 4 there is shown a diagrammatic representation of the various steps of a preferred embodiment of the process of the present invention.

Referring specifically to Fig. 1 there is provided a layer of photosensitive material 10, which is shown as having been exposed to a subject image to create developable portions indicated by the dots 16, these dots representing developable grains of photosensitive material. Various portions of the photosensitive layer 10 have different amounts of developable grains 16 therein, portion 10a having a maximum amount of developable grains, portion 10b having substantially no developable grains, and the portion 10c having about half of its grains developable.

In Fig. 2, the photosensitive layer 10 is shown as having been uniformly permeated with a solution of the reactive substance. This permeation is such that there exists a predetermined quantity per unit area of the substance distributed through the photosensitive layer 10. The uniform permeation is accomplished such as by dipping the photosensitive layer in a concentrated bath of the reactive substance, the photosensitive layer being in contact with the bath only long enough to absorb a predetermined quantity of the concentrated substance 14, either on its surface or within the layer 10. The photosensitive layer 10 should not be left in the bath long enough to permit the transfer of reacted portions of the substance from the layer 10 to the bath. The concentratlon of the bath should be so high that the photosensitive layer 10 may take up and support a uniform quantity of the substance, the concentration of the substance per un1t area supported by the layer 10 being preferably just enough to be completely reacted by a most reactive portion of the photosensitive layer 10. Other methods of applying the solution of the substance to the photosensitive layer are equally feasible such as spreading a predetermined layer 14 of a viscous solution of the substance in contact with the surface of the photosensitive layer 10. The substance may also be applied by other means such as by spraying etc.

After the solution has permeated the photosensitive layer 10, the reactive substance reacts with the developable portions 16. The distribution of one of the products of this reaction is indicated by the crosses 17, which may represent developed grains of photosensitive material. As can be seen, portion 10a of the photosensitive layer has a maximum amount of reaction product 17, portion 1011 has substantially no reaction product 17, and portion 100 has about half the amount of reaction product 17 as does the portion 10a. Since the amount of reactive substance with which the photosensitive layer 10 is permeated is preferably so adjusted as to be no more than enough to be completely reacted by the most reactive portion of the photosensitive layer, there remains in the portion 10a no unreacted substance. In the portion 10b, there remains a maximum quantity of unreacted substance, and in the portion 10c, there remains a quantity of unreacted substance which is about half that remaining in the portion 10b. Thus, in this case, the amount of reacted substance is a direct function of the exposure and the amount of unreacted substance is an inverse function of the exposure creating the negative image.

Referring now to Fig. 3, the photosensitive layer 10 is shown as having been formed into a permeable unit with an image-carrying layer 12 by being superimposed on said image-carrying layer in intimate relationship therewith such as in face-to-face contact. In this figure, the unreacted portions of the substance have migrated to the image-carrying layer 12, and exist within or on the surface of the image-carrying layer 12 in a quantity substantially inversely proportional to the amount of reaction of the substance in the corresponding portions of the photosensitive layer. In the portion 12a of the imagecarrying layer, which corresponds to the portion 10a of the photosensitive layer, there is substantially no unreacted substance on or within the surface of the imagecarrying layer 12. In the portion 12b of the imagecarrying layer there is a maximum amount of unreacted substance. In the portion 120, there is present about half the quantity of unreacted substance existing in the portion 12b. Thus, where a maximum amount of reaction between the substance and the photosensitive layer 10 has taken place, there is available in the image-carrying layer a minimum amount of unreacted substance. On the other hand, where there is a minimum amount of reaction with the photosensitive layer 10, there is a maximum amount of unreacted substance available on the imagecarrying layer. The portions of the substance which have reacted with the photosensitive layer 10 are preferably trapped within the photosensitive layer 10 so that no reacted substance migrates to the image-carrying layer in those portions where maximum reaction of the photosensitive layer has taken place. This trapping may be accomplished by a taming action of the substance upon the gelatin, or other colloid of the photosensitive layer, or it may be due to the decreased molecular or ionic mobility of the reaction product of the reaction, or it .may, where the substance is a developer, be the result of coupling between the oxidized developer and a relatively immobile dye-forming component contained in the photosensitive layer, or in the viscous developer solution used in the processing. In this latter case the developer .layer preferably adheres to the photosensitive layer. In

some cases it is not essential that the reacted portions of the substance be trapped in the photosensitive layer or the viscous layer, but it is preferred that these reacted portions of the substance be kept away from the image'- carrying layer, particularly where the reacted portions are capable of creating a color and thus spoiling the highlights and contrast of the positive image.

This selective distribution of the unreacted portions of the substance on the image-carrying layer 12 is assisted, in a preferred embodiment, by the use of a highly concentrated solution of the reactive substance and by superimposing the adjacent surfaces of the photosensitive layer 10 and the image-carrying layer 12 in intimate relationship during this transfer. Such an arrangement prevents any substantial dispersion of the reactive substance in its migration from the photosensitive layer to the imagecarrying layer.

The image in unreacted substance which exists on or within the surface of the image-carrying layer 12 is next utilized to form a visible image, preferably by the creation of a color on or within the surface of the image-carrying layer 12. This color may be created by the formation of a pigment or by the formation of a dye, the intensity of color created being dependent upon the amount of substance available for the color-creating reaction.

In Fig. 4 the final positive image is shown as being composed of a number of colored points, schematically sweatersi 7 represented at 51952 which-1 may: be color-,cr'eated byi aupigi mentr, .suchra's amcolloidal metal; orvwhichr niay bewcol 1'. crleeted by-rmolecules ofirdyer Fo'nasimplici ofr descrips tion; the colored? points 39 are lrepresentedas havingkan intensity depending on depth, while actually the in ten-; sitynof color may beprimarily' lat 'andsnear the surface ofigthezimagewcarrying layer, the, eifect'rdependingi upon the; intensity :of dye created, the sizetof; apigmentgcreated, or the; quantity per :unit area, of'color created. the portion 12a, ofwthe',image carryingrlayery'wher 'n'o: unreaoted; substance existed,v there isino format Ha colon; Inbportion: 1212;: thereiis produced amaximum intensity ofcolor; and; in; portion there is produced a ,color having about half; the intensity of the color pro duced in the portion 1 21); there; is thus produced .a colorwvhichiselect vely varies froinzp m to poi t hrougho t l- 7 1.163: fii h imag rry ng lay rv 2, bs n ial-1v inrzinv rserpror r ion o the amount of reacted photosensitivematerialin -the; corresponding portions; ;of";thei photosensitive. layer 102 Where the: image,- on:-.. h.,e ;ima e arrving:l y r 1 is formedjin terms' of a;pigment;119' and the-reactive suo stance-comprises a; developer; the unreacted -portions of the(1CVCIOPEITII1QY"bC US L o form-thie pigment}? by the redrtcingaction;pfi the developer on a;,redu ciele= inc tallic .s'alt. This-reducible metallit salt-can; be a salt which; i eg ib y p o ensi ive: uc met rou chloride or --a photosensitive salt; such as; asilver; halide; In he e, he:p gm ntcfcrm t cn el ctive, due to the selective reduction-- ofi;thezsalt-,; varying from point to point, and being a minimumewheroithere was- ;a'-maxi mum devolpmeht of the latenrnegat-ive:imageand-being a maximum where there was a5 minimum development ofthe latent negative image; Thereais thus .createdon the; image-carrying; layer a positive: pigmentimageof the latent negative image-in the ;-photosensitive layer.

When the reactive substance, is a-developer=and a dye image is formedon-Ihe image carrying layer 12,; there are, anumber of ways ofaccomplishing-the dyeferma-y tion, depending upon thetypelof developer utilized. In one; method, there may-be provided, for reaction with the unreacted portions of the developer, a color-former capable of coupling with these unreaoteds-is e., unoxid. ized, portions of the-developer torcreate acolonli); This color, due to itsseleotive:creation yariesinramount from point to point, beinga minimum where'therewas amaximum; dev lopm n f; J entr g iyeimag nd e g a maximum; where there- Wasa'; minimum development of the latent negative image. There is thus-"rcreatethon the image-carrying layerr1'2, apositive dye image of, the latent negative image in the photosensitive-layer. I

In another-methodof forminga; dye imagfiithere is utilized, to create a color, a color-former capable of coupling with oxidized, rat-her -than;.-unoxidizecl,- portions of the developer; In: this case, the developer is reactedwith the-photosensitive material containinga latent-negative image to: cause adevelopment; of the negative;imageresulting in a selective? oxidation; of the developer-and a trapping ofthe oxidized developer within the developed portions of the photosensitive layer;10, ,it being necessary-to prevent migration of theoxidizeddeveloper=from thephotosensitive layer The remainder-of thje developer is then 'utilized to create a color 19 on the image-carrying layer 12. In order to formthis color, it is necessary to oxidize-these unreactedportions of the developenafter the selective-re action-of the-developer with the latent negative --image; This oxidation-maybe accomplished; by providing'an oxidizing agent on the imagecarrying layer,- in which" case the oxidizingagent may be either a photosensitive material such as a silvcr halide or" a; nonphotosensitive; oxidizing; agent such as sodiumperborate; Itis also-contemplated to-oxidize the unreacted portionsof the developer on the image-carrying; layer by aerial oxidation which ,may be. carried out by separating the image-carrying 1 layer from the photosensitive layer whereby topermi-t the ready 21CCSS';Of oxygen from; theatmosphereto the-unseacted portionsofthe developer. After thedeveloperhas beenoxidized on the image-carrying layer it is reacted; with a suitablecolor-formertocause a coupling and the creationof a color, the concentration and distribution of which; varies from;;point to point substantially in inverse proportion to the-amount of development incorrespond ingportions of the latent negative image,

In both of the abovemethods' of .dye irnzigeformation Itcanei em.- hear hat causeiarcouplingi lhtifobfltwflellp is; preferably; locatedeons the lrnagezcarrying'layer 12-;in, solid form, lttrnay,.. li'o, ever, be coated on, orincluded in, the;photosensitive layer lll, onitlmay be,in sornejI cases,-;included:a:in'solui. tron; in theliguidi JCODIPOSIKIOH." This latter modification. of the-invention sparticularly-,fcasible where-:the (level opervis, coated on i one; ofithe 4 layers in solid-form rather than 'bein g in. -s'ol-ution in the liquid 1 composition.

Iu still"anothervinethodxofi forming -a dye, image, a self-couplingdeveloper isused; This developer, may-abe;

one ofthetypeknown in -the art as a direct color-forming:

developer, i. e., one which CQHPlflS Wilh' itselfiewhen oxi-, dizeda The developeris'; selectively. reacted=withnthe photosensitive material; containingatlatent negative image,

v and the; reacted" portions; are; preferably trapp'edg-irii the photosensitive; layer. Then the unreacted" portions? of. the: developer are utilized; to -selectively; create a -rcolo 19 onthe image-carrying layer.12,; byi oxidizing the un' reacted portions of the developer.

A preferred. method of permeating; the photosensitive layer-with a uniforrnouantit-yper unit aIBElyOf-QJ-ilqllld; composition containing the reactive; substance I is to re leasethe; liquid composition between the} photosensitive layer and; the irnage-carrying layerand to spread this. .llClUld 'CGfi'lPOSlfiOll in a, uniform thin layer; between the photosermitiye -layer and; the image-carrying :layerv Such;

a method of uniformpermeatiomhas certaimadyantages,

and is particularly adaptable-for -use ,-w rh'fil'Il1 i.lnll S;Of the type shown; inrFigs fi, 6 sand 7 whichlshow preferred examples ofq thephysieal embodiments l of, the; present inven tion.-

Each} of these-film units-may be-process'ed by'the appli cationgthereto of asingle mechanical stress to cause layer in position to permeate the photosensitive-layer with a uniform amount of: a solutioniof the stance.

Since the liquid composition-is preadhetween two. layers, Which'may be only. slowly-permeable-to-oxygcn; it substantially preventstthe accessof oxygen to'the-liquid composition during the timeitexistsina layer form reactive sub-J Withinthe' confines of the-film units This arrangementpreventslthe aerial oxidation of thegreactive substance; wheresuch-a substance is oxidizable.- Separatiomofi-the imagecarrying layer from the film-.unitrenders. the-surroundingatmosphere available for e'lljecting thev aerial oxidation ofoxidizable material-oaths image-carrying layer,- This feature permits the use of reactive, substances. Whicharequite easilyoxidizcd and prevents such-oxid tion until the positive image has formedpor; until itdesired to; oxidize=the reactive substance for the purpose of creating. a. positive image.

When the OllllfiFySllKfflCQ of the layers of the; filmunitare opaque, to actinic light, the construction of the-film unit. permits the liquid composition, particularly where,

the liquid is viscous, to form a lightproof laminate, ofthe filmunit so ,thatthe film unit maybe ejected. from a camera. into daylight, immediately after the mechanh cal treatment. Exposure of thesphotos'ensitive, layer isefiected prior to the iormationof said lightproofi laminateand with the. photosensitive and. the image-carrying layers-in spread apart or separatedrelation with-respect to each other. Since the compositelaminate is opaque to actinic light, the photographic processmaybe carried. to compietionoutside; of the cantera-withno danger olfdestroyingt thelatent image as' the, result of light reaching. the photosensitive material.

Such-Jfilm units should havecertain features-in. order thatthey may fulfill the requirements of-the process, In the firstplaCC, it is preferable that the; film units have within theirconfines. all the-materials neeessarvfor the completeprocessing thereof to produce the -final positiveimage, .lnthe second place, the film units shouldbeso designed that they, may inherently assure the proper se quence-of reactions, or-canbeso used asto assure this proper sequence ofreactions.

The physical embodiment of ,the; broad inventiomshovt n,

infigs. 5, 6 and 7, generallyinyolvesa' composite film unit comprising, a photosensitivelayer, an imagegcarrying m the;c01Qr,-, o.rm@ hic l is e cte withi hedev l p r c "F r nd a n iner w a n d HQ EEIQJLL hQ can-i;

tainer being positioned in the film unit for release of its liquid composition so as to permit the permeation of the liquid into at least the surface portions of the photosensitive and image-carrying layers. The liquid composition is preferably viscous and preferably includes the reactive substance, and at least includes a solvent therefor.

The film unit of Fig. 5 preferably comprises a photosensitive layer 30, an image-carrying layer 32, and a container 34 having therein a liquid composition and positioned to release its liquid between the two

layers

30 and 32. For supporting the photosensitive layer 39 there is provided a usual film base 36.

In another physical embodiment of the invention, shown in Fig. 6, there is provided a film unit of the general type described in connection with the discussion of Fig. 5, the embodiment of Fig. 6 being particularly useful in those processes described previously where the reactive substance reacts with a material on the image-carrying layer to create a color.

Referring now to Fig. 6, where like numbers correspond to like elements of Fig. 5, there is provided the usual layer 30 of photosensitive material, carried by a base layer 36. An image-carrying layer 32 is also provided. On that surface of the image-carrying layer 32 which is closest to the photosensitive layer 30 there is provided a coating or layer 38 of a material which is only slowly permeable to a liquid composition within a container 34.

In general the embodiment of the invention of Fig. 6 is usable with all processes of the type discussed previously and is particularly useful for those processes wherein a developer is the reactive substance and the imagecarrying layer 32 contains a material which is quite reactive with the developer, the reaction of the developer with'the material being that which creates a color constituting the positive image.

In still another physical embodiment of the invention there is provided a composite film unit comprising a photosensitive layer and an image-carrying layer similar to the embodiment of Figs. 5 and 6 but having its various layers so arranged with respect to the introduction of the liquid composition that the liquid composition must per-- meate through the layer of photosensitive material before reaching the image-carrying layer. Such an embodiment of the invention is shown in Fig. 7 where like numbers correspond to like elements of Figs. 5 and 6.

Referring specifically to Fig. 7 there is provided a usual photosensitive layer 30 coated on the upper surface of an image-carrying layer 32. A container 34 is provided in the film unit in a position to discharge its liquid composition adjacent that surface of the photosensitive layer 30 which is farthest from the image-carrying layer 32. For assisting in spreading the liquid composition in a uniform thin layer adjacent the surface of the photosensitive layer 30 there is provided a relatively impermeable backing layer 40.

The embodiment of Fig. 7 may be utilized with any of the processes previously described and it has particular advantage in those processes wherein the reaction of the reactive substance with the negative must be completed before the liquid composition permeates the image-carrying layer.

In the above-described processes portions of a reactive substance, such as a developer, are selectively rendered incapable of creating a color by reaction with a layer of photosensitive material containing a latent negative image to cause the development thereof, and the unreacted portions of the reactive substance are utilized in a color-creating reaction to form a positive image on an imagecarrying layer. In such processes it is essential to carry the first reaction to substantial completion before the second reaction commences. The proper sequence of the two reactions is obtainable in numerous ways.

One way of obtaining the proper sequence is described above in connection with the discussion of Figs. 1 through 4, where the development of the latent negative image is accomplished while it is separate from the locale of the second reaction, i. e., before it is formed into a permeable assembly with the image-carrying layer 12. This way of assuring the proper sequence between the two reactions is not as preferred as those ways to be discussed hereinafter, since it is not particularly adaptable for use with a compact apparatus such as a hand camera.

When film units'of the type of Figs. 5, 6 and 7 are utilized with the process of the present invention and the liquid composition is spread in a uniform layer within the film unit while the various layers thereof are in permeable relationship to each other, the proper sequence of reactions may be assured by providing the proper physical and/lor chemical relationship between the various materia s.

There are a number of forms that this relationship may take. The first form, which is particularly useful with the embodiment of Fig. 5, involves the provision of materials such that the development of the latent negative image is inherently faster than the color-creating reaction which forms the positive image. An example of this modification of the invention is one wherein the silver halide in the latent negative image is more readily reducible than the metallic salt on the image-carrying layer. Another modification of this form of the invention, useful with the embodiment of Fig. 5, involves the provision of an oxidizing agent on the image-carrying layer which oxidizes the developer more slowly than the developer develops the latent negative image.

Another form of a relationship of material for assuring the proper sequence of reactions is the provision of some means for temporarily preventing the color creating reaction. This means may comprise a coating, as shown in Fig. 6, on the surface of the image-carrying layer or a hardened surface on the image-carrying layer which is adapted to retard penetration of the developer into the image-carrying layer until such time as the developer has been selectively reacted by the latent negative image in the photosensitive layer. Materials suitable for such a coating, as will appear in the more detailed examples which illustrate the invention, comprise polyvinyl alcohol, cellulose nitrate and the like.

Another way of assuring the proper sequence of reactions is to provide a process, particularly useful with the embodiment of Fig. 5, wherein the image-carrying layer must be subjected to a definite treatment before the unreacted developer, on its surface, may enter into the color creation reaction. In one form of this modification of the invention there is provided, on the imagecarrying layer, a layer of unexposed photosensitive material. In this case, the unreacted developer cannot reduce this unexposed photosensitive material until it has been made developable by exposure to light. In another form, where there is used a developer which, when oxidized, couples with itself or another substance, this coupling can be prevented, if no oxidizing agent is included on or within the image-carrying layer, or if the oxidizing agent must be treated, such as by exposure to light, before it is capable of oxidizing the unreacted portions of the developer. In this case, the developer cannot couple until the image-carrying layer has been exposed to aerial oxidation or the oxidizing agent has been activated such as by being exposed to actinic light.

Still another way of assuring the proper sequence of reactions, as shown in Fig. 7, is to adjust the direction of permeation of the developer so that it permeates through, and is substantially completely reacted by, the photosensitive layer before reaching the image-carrying layer.

In the above discussion of the processes applicable to Figs. 1 through 4 and Figs. 5, 6 and 7, no mention is made of the preferred materials. These materials vary in accordance with the specific processes involved and are discussed in more detail hereinafter.

In the following discussion of preferred examples of the various processes of the present invention it may be assumed that all the processes may be practiced as shown in Figs. 1 through 4 and are usable with the modifications of the physical embodiments of the invention shown in Figs. 6 and 7, by suitably arranging the reactive material on the image-carrying layer and either supplying a protective slowly permeable coating thereover or causing the reactive substance to permeate through the photosensitive layer before it contacts the reactive material. Where the process is also particularly well suited for use with a film unit of the type shown in Fig. 5, it is so stated. In the following examples the numbers refer to Figs. 1 through 4 unless the process is particularly applicable to one of Figs. 5 through 7.

One method of creating a dye positive image from a latent negative image is to use on the image-carrying layer a material capable of coupling with unreacted portions of a reactive substance, such as a developer, to form a dye. This dye may be formed by the use of a color-former, or dye base such as a diazonium fast salt, on the image-carry- 'ing layer, which is capable of coupling with unreacted por- 9 tions of an amine or phenol developer. Such a process is set-forth in the following nonlirniting example:

EXAMPLE 1' The image-carrying. layer 12, which may be conventional baryta coated paper, is prepared-by'coating' with a water solution of Naphthosol East Orange Salt GC and allowed to dry. Naphthosol'Fast Orange SaltGC is stabiliz'edand diazotized' meta chlor aniline (American Dyestuif Reporter, 1939, vol. 28, No.4, pp. 82-83).. The'pjhot'osensitivelayer ll) comprises'a relatively slow, high contrast orthochromatic silver halide emulsion, such as'is employed with copying film, commonly known tothe'trade as contrast process ortho film. The photosensitive layer'is'exposed to actinic light and permeated'with ad'ev'eloper by dipping for a few seconds in a solution'of LS-dihydroxynaphthalene. Development of the photosensitive'layer is continued for several minutes after removal from the developer bath. The developed photosensitive-layer is'then placed in contact withthe'image carrying layer to cause the unreacted portions of the developer" tomigra'te to the surface of the image-carrying layer where they couple with the NaphthosolFast Orange Salt 5C to form a positive dye image on the image-carryinglayer. This image appears to be intensified by the aerial oxidation of the unreacted developer after the initialpositive'imageis formed. Thus the'irnage appears to be formed by the unreacted portions of the developer which couples, partially in its unoxidizedand partially in its oxidizedcondition', with the color-former. Those portions of the d'evelop'eroxidized as the result of the development ofthe'latentnegative image appear to be trapped within the photosensitive layer and thus cannot spoil the positive image.

In another method of forming a dye positive image from a latent negative image there is utilized a color-former capable of coupling with oxidized, rather than unoxidized, portions of the developer. Such aprocesswhere thecolorformer is contained in the liquid is described'in the' following nonlimiting example:

EXAMPLE '2 The photosensitive layer 19, which may comprise an ortho-chromatic emulsion of the character described in connection with Example 1, is exposed'toactinic light to create therein alatent negative'image. ThisQla'tent negative image is developed'uslng the following'de'velope'ri Diethylparaphenylenediamine hydrochloride grams 6 Sodium sulphite do 10 Potassium bromide do 0.5 Sodium carbonate do 11 7 Color-former (p-nitrophenylaeetonitrile') do 0.10 Water cc 2000 Acetone cc 10 The negative is removed from the above developing both after approximately 5 seconds and development is allowed to continue for a minute and a half. The developed negative is then pressed into contact with an image-carrying layer 12 containing an oxidizingagent. Such an image-carrying layer may be prepared by swabbinga sheet of paper, known in the art as imbibition paper, with a 10% solution of sodium perborate. The negative is left in contact with the image-carrying layer for approximately four minutes to permit the sodium perborateto oxidize the unreacted portions of the developer so thatth'ey may couple with the color-former. The negative is then separated from the image-carrying layer to reveal thepositive dye image on the image-carrying layer. The image obtained by this process is magenta and may be utilized to advantage in three-color photography.

EXAMPLE. 3

A cyan positive image may be obtained in Example 2 by using, as the color-former, 2,4-dichloro-1-naphthol.

EXAMPLE 4 10 of'thedeVeloper have been transferred to theimage-earrying la yer: In-this ease the'developer'solution is the sa'me except that no color-former is included therein.

In'the' above specific example, sodium perborate' was use'd as the oxidizing-agent for oxidizing those portionsof theheveloperunreacted by the development of thelatent negative image. Other-non-photosensitive oxidizing agents suchas'sodiumperchlorate; ammonium dichromate, and ammonium persulfate may also be used.

It is also contemplated touse aphotosensitiveoxidizing agent on or within the surface-of the image ca'rryin'g layer. Such a photosensitive-material can be a silver halideand is preferably dispersed within thesurface of the paper. This photosensitive:material can beeither exposed or unexposed depending upon thedesiredtype of process; If exposed, it reacts with'the developer as soon as it contacts the developer. If unexposed, it must be exposed to actinic light, or otherwise madedevelopable, before it can oxidize the developer. This latter condition has certain advantages since it enables the use of such an unexposed oxidizing agent-with a film unit ofthe type shown in Fig. 5

I In'practicing the above modification of the invention it is'equally possible to rely on aerial oxidation as thesole means for oxidizing the unreac ted portions of the developer as set forth in the following example:

EXAMPLE 5 The process of Example 2'is modified by eliminating the o'xidizing'agent from the image-carrying layer 12. When the image-carrying layer has been imbibed with the developed negative for 4 or 5- minutes itis separated therefrom andthe invisible image in unreacted developer on the surfaceof the-image-carrying layer is exposed to aerial oxidation. As the developer oxidizes it couples with the color-former to create a color and'thus produces apo'sitiveimage.

In the'process of the type of Example 2, where a colorformer couples'withthe oxidized developer, it is desirable toinsure the trapping, within the photosensitive layer, of all the developer that is oxidized-by the development o'f the latent negative image. Such a trapping maybe-improved by; including within thephotosensitive'layer 10 a color-former that-couples with the oxidized developer to form a relativelyimmobile dye. Thus,-asthe developer is oxidized by the development of'the latent negative image, it immediately couples with the color-former'in the photosensitive layer- 10 and is converted into an immobiledye, thereby being trapped within the photosensitive layer. This is particularly desirablewhere the color-forme'r'used to create the QsitiVeimage is-placedon the image-carrying layer rather-than in the developer solution.

In-stillaanother: method of-forming a dye positive image from. a latent'negativeimage, a self-coupling developer is used. This developer may be one of the type known inthe art as a direct color-forming developer, i. 6., one which couples with itself to form a dye when oxidized, as'set forth in the following nonlimiting example:

EXAMPLE 6 A- layer: of silver. halide photosensitivefilm 3036 of Fig. 5, such as orthochromatic copying film of the type described" in Example 1,.is exposed to asubject' image. A preferred form of image-carrying layer 32 comprises a sheet of imbibition paper. A suitable liquid composition r contains the following materials:

Water' cc-- 476 Sodium .carboxymethyl cellulose grams 42.6 Sodium hydroxide do 17.5 1,5-dihydroxynaphthalene do With sucha liquid'composition, the process is'prefefi ablycarried out by spreading a thin layer of the'liquid composition between the exposed photosensitivelayerfill and the image-carrying layer 32. This spreading may be accomplished by releasing the liquid composition'from a container 34 positioned between these two layers and spreading the liquid by means such as a pair of pressure rollers. The 1,5-dihydroxynaphthalene develops the latent negative image and, where development occurs, it selfcouples to form an immobile dye. Where development does not occur, the unreacted. developer migrates to the surface of the image-carrying layer. The image-carrying layer 32, withthe positive image in termsof u'n're'a'cted developer'on its'surface, is thenseparated from the'photo sensitive-layer 30-and exposedto air'so astooxidiz'e'the" ;the image-carrying layer.

unreacted developer. This oxidation causes the developer on the image-carrying layer to self-couple, thus creating a color and forming a positive image of the subject image.

It is equally possible to use oxidizing agents on the image-carrying layer of Example 6 rather than relying on aerial oxidation to oxidize the unreacted developer on In such a case the film unit should be of the form of Fig. 6 or 7 and the oxidizing agents may be of the various types discussed in connection with Examples 2 through 4 above.

Where the positive image on the image-carrying layer is formed in terms of a color created by a pigment, as distinguished from a color created by a dye, the unreacted .portions of the developer may be used to form this pig- -ment by the reducing action of the developer on a reducible salt, as set forth in the following nonlirniting example:

EXAMPLE 7 The layer of photosensitive material preferably I Grams Hydroquinone .2 Sodium sulphite 37.8 Sodium hydroxide 36.1

Water 900 The layer 10 is removed from the bath after about seconds and development is allowed to continue for about 2 minutes. The developed negative image, containing an invisible image in unreacted developer, is then placed in intimate contact with an image-carrying layer comprising a sheet of uniformly exposed photosensitive paper such as a relatively fast, conventional enlarging paper having an emulsion comprising silver bromide and silver chloride. The unreacted developer permeates and develops the exposed photosensitive grains in the imagecarrying layer and thus develops a positive image in silver on the image-carrying layer. The undeveloped grains in the image-carrying layers are then preferably fixed out by bathing in a suitable silver halide solvent, such as a solution of sodium thiosulphate.

The process of Example 7 has been described in connection with a process of the type shown in Figs. 1 through 4. It may equally be used in film units of the type shown in Figs. 6 and 7, or in a film unit like Fig.5 where the imagecarrying layer is sufficiently impermeable so as to I! I delay permeation thereof by the developer. If it is desired to include a silver halide solvent in the liquid composition for the purpose of removing unreduced silver halide from the image-carrying layer of Example 7 the photosensitive material in the photosensitive layer 30 is made of less soluble material than the silver halide in the image-carrying layer. The unreduced silver halide may be removed from the image-receiving layer to a protective colloid film formed between the image-carrying layer and the photosensitive layer by a plastic material such as sodium carboxymethyl cellulose carried in the liquidprocessing composition or this unreduced silver halide may be transported to the base which supports the photosensitive layer.

In still another modification of the invention, a nonphotosensitive salt is added to the image-carrying layer for the purpose of making available a material which can be reduced to a pigment by unreacted portions of the developer. This salt may be added after the invisible image in unreacted developer has been formed on the surface of the image-carrying layer. One method of practicing this feature of the invention is set forth in the following nonlimiting example:

- EXAMPLE 8 A copying film, of the type heretofore described, is used Solution A Sodium carboxymethyl cellulose grams 20 Water cc Sodium hydroxidegrams 3 Hydroquinone 9 Water to make 300 grams.

This development is preferably accomplished by spreading the liquid composition in a uniform thin layer between the photosensitive layer 30 and the image-carrying layer 32 of Fig. 5. This spreading is preferably accomplished by releasing the liquid composition from a container 34 therefor positioned between the two layers. After several minutes the image-carrying layer 32 is separated from the photosensitive layer 30 and there is seen an extremely faint yellowish image, which apparently is an image in unreacted developer which has started to oxidize. The image-carrying layer 32 is next swabbed with a dilute solution of silver nitrate and a gray positive image is developed as the result of the reduction of the silver nitrate by the unreacted developer.

EXAMPLE 9 A yellow positive image can be obtained in the process of Example 8 by swabbing the image-carrying layer 32, containing an invisible positive image in unreacted developer, with a salt such as ferric chloride, chromic trioxide or platinum chloride.

In another modification of the invention wherein unreacted portions of the developer are utilized for creating a color in terms of a pigment, a nonphotosensitive salt is selectively reduced to colloidal particles by these unreacted portions of the developer, as set' forth in the following example:

EXAMPLE 10 An image-carrying layer 32 of Fig. 5 is formed of baryta paper and is prepared by swabbing with a 2% solution of chloroplatinic acid. The photosensitive layer 30 and the base layer 36 may comprise a sheet of Contrast Process Ortho film. With such materials the liquid composition in the container 34 preferably comprises:

Water cc 476 Sodium sulphite grams 9 Sodium hydroxide do 19.6 Sodium carboxymethyl cellulose do 42.6 Hydroquinone do 9 The film unit is processed by exposing the photosensitive layer 30 to actinic light and then passing it through a wringer. The layers are kept together for a few minutes and then separated to reveal a yellow positive image on the image-carrying layer.

EXAMPLE 1 1 An image-carrying layer 32 of Fig. 5 is formed of baryta paper and is prepared by swabbing with a 2% solution of palladium chloride. The photosensitive layer 30 and the base layer 36 may comprise a sheet of the heretofore described copying film. With such materials the liquids composition in the container 34 preferably comprises:

Water cc 476 Sodium sulphite grams 9 Sodium hydroxide do 4.9 Sodium carboxymethyl cellulose do 28.4 Hydroquinone do 9 The film unit is processed by exposing the photosensitive layer 30'to actinic light and then passing it through a wringer. The layers are kept together for a few minutes and then separated to reveal a yellow positive image on the image-carrying layer.

EXAMPLE 12 13 Another modification ofthe invention wherein the reaction of the developer with the negative image is inherently faster than the color formin'g reaction is described in the following nonlimiting example:

EXAMELE 13 The photosensitive layer 3i? and the base layer 36 of Fig. may comprise a silver halide photographic film such as the heretofore described copying film. For use With this photosensitive layer 30 the liquid' composition in the container 34 preferably comprises:

Grams 5916 water solution of sodium carboxymethyl cellu- Sodiunr hydroxides- 1 Sodium. sulphite e. n.;t e l e 2.5 Pyrocatechin i i I a 0.5

The image-carrying layer" 32 is preferably formed or a sheet of baryta paper which has been swabbed with a color-former capable of coupling with unreacted portions of the pyrocatechin. Such a color-former may be applied by: making an alcohol and water solution of Naphthosol Fast Orange Salt GC. The photosensitive layer 30 is exposed to actinic light, and the developer is then spread between the exposed photosensitive layer 30 and the image-carrying layer 32by the use of pressure rollers or other suitable means. The pyrocatechin appears-to react first With the latent negative image in the photosensitive layer 3!), and thenthe unreacted portions thereof migrate to the image-carrying layer Where they couple with the color-former o'nthe image-carrying layer to give apositive image. V

In still another modification of the embodiment of Figs 5 wherein a dye positive'image-is obtained, a process is used which is similar to thatdescribed in Example 2. In the following example there is shown a method of practicing this-feature of the invention with the modification of Fig. 5 wherein the proper sequence of reactions is assured by using an oxidizing agent which oxidizes the developer more slowly than the developer develops the latent negative image:

EXAMPLE l4 The photosensitive layer 30 and the baselayer 36 preferably' comprise a sheet of the copying film of the preceding. examples, and the image-carrying. layer 32 comprises aisheet of baryta paper which has beenswabbed with a solution ofsodium perborat'el A preferred liquid composition comprises:

Grams Diethylparaphenylenediamine hydrochloridefl u- .75 Sodiumv sulphitev i 1.5 Potassium bromide 0.6 5% waten solution of sodium-carboxymethy cellulose I 131 Sodium carbonate 14.62 2-,4-dichloro1-l-naphthol' (color-former .1

After exposure of the photosensitive layer to actinic light to create therein a latent negative image, the film unit is'processed to release the liquid' composition from the container 34 and tospread the liquid in a uniform thin layer between the photosensitive layer 30 and the image-carrying layer 32; The developer" (diethylparaphenylenediamine hydrochloride) develops the latent negative image and, Where development occurs, it couples with the color-former and apparently is trapped within the negative by forminga relatively'immobile dye. The unreacted portions of the developer are then slowly oxidizedl'by the sodium perborate on=the image-carryinglayer. As. these portions. are oxidized they couple with the color former. tocreate a color on the image-carrying layer constituting the positive image. a v

A -specific modification of the embodiment of Fig. 6 is described= in the following nonlirniting example wherein ametallic'salt is selectively reduced byunreact'ed portions of" a developer and a slowly permeable polyvinyl alcohol coating? is placed over the metallic salt toassure a proper sequenceof reactions.

nitrate o 200 cc1- of a 3 per cent nitric acid solution. A-

sheet of baryta pap'erg for useas the image-carryin layer 32, is placed in this solution for two minutesand'the excess solution is removed from the sheet by the'use of squeegee. "the sheet is then soalted in a 10 per cent solution of sodium chloride for two minutes, thus forming mercurous chloride in the surface of the baryta paper. The sheet is then dried in air at room temperature. To one surface of a sheet prepared as above there is laminated a layer 38 of polyvinyl alcohol. This layer 38 of polyvinyl alcohol is preferably in the neighborhood of .0006 inch thick and is laminated to the baryta sheet by using a water solution of polyvinyl alcohol.

For use with the above described composite sheet 32-38 a liquid composition in the container 34' preferably comprises the following ingredients:

Grams Water r 7 I860 Sodium carboxymethyl cellulose 116 Sodium sulphit 78 Sodium hydroxide 74.6 Citric acid 38.5

Hydroquinone 52 In preparing this liquid composition, the Water and sodium carboxymethyl cellulose are mixed for two hours. Then all of the other elements, except the hydroquinone; are added and mixed for 5 minutes. Lastly the hydroquinone is added and the whole batch is mixed for two hours at 50 C. under an atmosphere of nitrogen.

For the negative photosensitive layer 3036 a preferred material is a sheet of the previously mentioned copying film. The photosensitive layer 30 is exposed to a subject image and the film unit is processed, as by passing it through a pair of pressure rollers to release the liquid composition from the container 34- and to spread the liquid in a uniform thin layer between the photosensitive layer 30 and the polyvinyl alcohol coating 38. When the above described liquid composition is spread between the exposed photosensitive layer 30 and the polyvinyl alcohol coating 33 on the image-carrying layer 34, the developer develops the latent negative image in the photosensitive layer, this development being substantially completed before any substantial permeation of the polyvinyl alcohol layer 38 takes place. Where the developer is unreacted by this development, it permeates through the polyvinyl alcohol coating and reduces the mercurous chloride on the surface of the image-carrying layer to colloidal black particles forming a positive image of the latent negative image.

While the above modification of the invention describes a preferred form thereof, numerous other materials and processes may be utilized. The slowly permeable'layer 38 may comprise plastics other than polyvinyl alcohol, and reducible salts other than mercurous' chloride may be used; The liquid composition is also susceptible of Wide varia-' tions without departing from the scope of the invention;

While the slowly permeable layer 38 of polyvinyl alco' 1101 is preferably applied in the form of a sheet by laminat ing to the image-carrying layer, it is equally possible to cast, from an aqueous solution, a layer 33 of polyvinyl alcohol directly on the surface of the prepared imagecarrying layer 32 by the use of a doctor blade or other coating techniques.

The slowly permeable barrier layer 33 may equally be formed of a plastic such as cellulose nitrate, as set forth in the following example:

/ curous chloride, is dipped in a bath containing a 2% nearest the photosensitive layer.

one-half second cellulose nitrate solution in equalparts of butyl alcohol and butyl acetate. The sheet is dried, andthelayer of cellulose nitrate is found to be approximately .0001 to .0002 inch thick over the mercurous chloride.- Such a sheet is preferably used with a developer of the type mentioned above.

in the embodiment of the invention of Figs. 5, 6 and 7, the material which reacts with the developer on the image= carrying layer 32 may be situated on the surface thereof Ifsuch' be the case with respect to Fig. 7, the photosensitive layer30 is preferably so formed that it may be readily separated from the image-carrying layer 32. This separation may be assisted by including'within the liquid composition a film-forming: material, such as sodium carboxym'eth-yl cellulose; which i is capable of forming a strong adhesive bond betweeti'th'e' photosensitive layer 30 and the backing layer 40. Thus when the image-carrying layer 32 is separated from the backing layer 40, the photosensitive layer 30 adheres to the backing layer 40. The photosensitive layer of Fig. 7 may, if desired, be carried by a suitable permeable base material such as a sheet of gelatin, in which case the base can be mounted with respect to the image-carrying layer so as to be readily separable therefrom as in the manner of conventional stripping film.

In another modification of Figs. 5, 6 and 7, the material which reacts with the unreacted portions of the developer is situated on the surface of the image-carrying layer farthest from the photo-sensitive layer. In this case no separation of the various layers of the film unit is required in order to view the positive image. Visibility of the negative image, in instances where the layers of the film unit are to remain unseparated after positive image formation, may be prevented by the use of a suitable opaque material, for example baryta paper, for the imagecarrying layer.

In still another modification of the embodiment of Figs. 5, 6 and 7 there may be one reactive material on one surface of the image-carrying layer and another reactive material on the other surface of the image-carrying layer. As an example of such an arrangement, as applied to Fig. 7, an oxidizing agent may be included on the upper surface of the image-carrying layer in a position to oxidize unreacted portions of the developer as it permeates through the composite film unit. On the lower surface of the image-carrying layer there may be a color-former capable of coupling with the oxidized developer. As the developer reaches the color-former on the lower surface it couples therewith to form a positive dye image.

In the physical embodiments of the invention represented by Figs. 5, 6 and 7, the container 34 preferably comprises a paper-backed metal foil coated on its inner surface with a resin, such as polyvinyl butyral, which is inert to alkalies, although it may take numerous other forms.

The liquid composition in the container 34 preferably comprises an aqueous solution of the reactive substance. For assisting in spreading the liquid in a uniform film, the liquid preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when spread over a water-absorbent base, will form a relatively firm, dimensionally stable film. Where the aqueous solution is alkaline, the film-forming material is preferably one which is not hydrolyzed in an alkaline solution. A preferred film-forming material is a high molecular weight polymer as, for example, a polymeric, water-soluble ether inert to an alkali solution, such as hydroxyethyl cellulose or a metal salt of carboxymethyl cellulose, e. g., sodium or aluminum carboxymethyl cellulose. Other film-forming materials or thickening agents can be used for the conversion of nonviscous solutions to viscous solutions where the conditions are such that their ability to increase the viscosity of the solution is not destroyed when left in solution for a considerable length of time. The viscosity of the liquid composition is preferably in the neighborhood of 20,000 centipoises although it may be as low as 8 centipoises. The high viscosities are preferred, since they give a more accurate control of spreading of the liquid composition.

In the various physical embodiments of the invention, the liquid composition in the container 34 preferably comprises an aqueous solution of the reactive substance. In some cases, however, it is desirable to include the reactive substance, such as a developer, in or on one of the layers of the film unit and for the liquid composition to include only water, possibly an alkali, and possibly a film-forming material to aid in accurate spreading. In other cases, the liquid composition may, for example, comprise only an aqueous solution of the developer, and there may be included in solid form in one of the layers of the film unit any alkali which may be required.

In still another modification of the physical embodiment of the invention the film unit may contain no liquid and may contain, in solid form, all of the various materials ordinarily carried in solution within the film unit.

Such a modification of the invention is not as preferred as those described, since it requires the addition of a solvent to the film unit and thus cannot be processed by the mere application of mechanical stress to the film unit. Such a modification of the invention is, however, included within the scope of the present application.

The image-carrying layer, while being preferably formed of papers such as those known in the art as baryta paper or imbibition paper, may be formed of numerous other materials such as a water-permeable plastic or a water-permeable, reversible, film-forming organic colloid capable of having high viscosity characteristics and appreciable jelly strength, in which dye bases or salts may be suspended.

Examples of other suitable image-carrying layers are regenerated cellulose; polyhydroxy alkanes, such as polyvinyl alcohol; sodium alginate; cellulose ethers, such as methyl cellulose, or their derivatives, such as sodium carboxymethyl cellulose or hydroxyethyl cellulose; papers; proteins, such as glue or gelatin; carbohydrates, such as gums and starch; and mixtures of these materials where the latter are compatible. Where the above materials are transparent they may be mounted on an opaque base if desired, or have incorporated therein a colloidal pigment to render them opaque.

Throughout the specification and appended claims the expression positive image has been used. This expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive layer. As an example of an alternative meaning for positive image, assume that the photosensitive layer is exposed to actinic light through a negative transparency. In this case the latent image in the photosensitive layer will be a positive and the image produced on the image-carrying layer will be a negative. The expression positive image is intended to cover such an image produced on the imagecarrying layer.

In preceding portions of the specification the expression color has been frequently used. This expression is intended to include the use of three colors to obtain black.

Throughout the specification and claims the expression superimposing has been used. This expression is intended to cover the arrangement of two layers in overlying relation to each other either in face-to-face contact or in separated condition and including between them at least one layer or stratum of a material which may be a viscous liquid.

Since certain changes may be made in the above process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A process of forming positive transfer images in color wherein a single application of liquid to the exposed silver halide emulsion of a photosensitive element produces the necessary sequences of reactions for giving the finished positive print, said process comprising the steps of: permeating said silver halide emulsion with a liquid composition, and, during said permeation, having said silver halide emulsion so superposed on an image-receiving layer that said liquid has access to the latter layer; providing within the lamination comprising said photosensitive element and said image-receiving layer a reagent capable of developing exposed silver halide to silver and capable of reacting in the presence of an oxidizing agent to give a dye and comprising a primary color-forming silver halide developer, said reagent being so distributed throughout said lamination as to have a substantially constant depthwise concentration per unit surface area of said lamination and being present per each said unit area substantially only in such a quantity as to cause said reagent to be substantially completely reacted within the emulsion in the event of the full development of the silver halide of said unit area, said reagent being dissolvable in said composition when contacted thereby and when dissolved therein being mobile in said lamination; developing the latent image in the silver halide emulsion by means of said reagent and causing so much of the said reagent as is oxidized in development of silver to participate in the formation of a dye image in the emulsion and to there effect the exhaustion of the reagent for participation in providing image dye in proportion to silver development for each said unit area of said lamination; transferring to said image-receiving layer in solution in said composition at least a part of the unreacted portion of said reagent; thereafter, causing the transfer of the unreacted portion of said reagent to react within the image-receiving layer in the presence of an oxidizing agent to produce a dye image in said layer; and, throughout said process, maintaining said image-receiving layer free of appreciable amounts of silver, silver salts and material which, during said process or in the presence of light and air, will impart to said image receiving layer a color that will adversely affect the visibility of the said image in the image receiving layer.

2. In a process of forming positive transfer images in color as defined in claim 1, the step of separating the image-receiving layer and said photosensitive element from their superposed relationship at some stage of said process after the unreacted portions of said reagent have been transferred to said image-receiving layer.

3. A process of forming positive transfer images in color as defined in claim 1 wherein said reagent is contained in said liquid composition when the liquid com position is permeated into said silver halide emulsion.

4. A process of forming positive transfer images in color as defined in claim 1 wherein said reagent is contained in said liquid composition and the image-receiving layer is part of a separate element, and wherein said process includes the step of retarding the contact of said liquid composition with said image-receiving layer by causing said liquid composition, before coming into contact with said image-receiving layer, to pass through a stratum of material which is located between said emulsion and said image-receiving layer and which is characterized by being slowly permeable to said liquid cornposition.

5. A process of forming positive transfer images in color as defined in claim 1 wherein the permeation of 18 said emulsion with said liquid composition is effected by the step of providing a layerwise distribution of said liquid composition between said photosensitive element and another element, the latter element supporting said imagereceiving layer.

6. In a process of forming positive transfer images in color as defined in claim 5, the step of separating said image-receiving layer and said photosensitive element from their superposed relationship at some stage of saidprocess after unreacted portions of said reagent have been transferred to said image-receiving layer.

7. A process for forming positive transfer images in color as defined in claim 1 and including the steps of providing a layerwise distribution of liquid composition having said reagent dissolved therein between said emulsion and a stratum of material which is located on said image-receiving layer and is characterized by being less permeable to said liquid composition than said emulsion and permeating said emulsion with liquid composition from said layerwise distribution While retarding contact of liquid composition with said image-receiving layer until said liquid composition has passed through the stratum of lesser permeability.

8. A process of forming positive transfer images in color as defined in claim 1 and including the step of effecting the oxidation of the unreacted portion of said developer which is transferred to said image-receiving layer with an oxidizing agent substantially uniformly distributed throughout at least a stratum of said image-receiving layer adjacent the surface thereof to which said reagent is transferred.

No references cited.

Claims

1. A PROCESS OF FORMING POSITIVE TRANSFER IMAGES IN COLOR WHEREIN A SINGLE APPLICATION OF LIQUID TO THE EXPOSED SILVER HALIDE EMULSION OF A PHOTOSENITIVE ELEMENT PORDUCES THE NECESSARY SEQUENCES OF REACTIONS FOR GIVING THE FINISHED POSITIVE PRINT, SAID PROCESS COMPRISING THE STEPS OF: PERMEATING SAID SILVER HALIDE EMULSION WITH A LIQUID COMPOSITION, AND, DURING SAID PERMEATION, HAVING SAID SILVER HALIDE EMULSION SO SUPERPOSED ON AN IMAGE-RECEIVING LAYER THAT SAID LIQUID HAS ACCESS TO THE LATTER LAYER; PROVIDING WITHIN THE LAMINATION COMPRISING SAID PHOTOSENSITIVE ELEMENT AND SAID IMAGE-RECEIVING LAYER A REAGENT CAPABLE OF DEVELOPING EXPOSED SILVER HALIDE TO SILVER AND CAPABLE OF REACTING IN THE PRESENCE OF AN OXIDIZING AGENT TO GIVE A DYE AND COMPRISING A PRIMARY COLOR-FORMING SILVER HALIDE DEVELOPER, SAID REAGENT BEING SO DISTRIBUTED THROUGHOUT SAID LAMINATION AS TO HAVE A SUBSTANTIALLY CONSTANT DEPTHWISE CONCENTRATION PER UNIT SURFACE AREA OF SAID LAMINATION AND BEING PRESENT PER EACH SAID UNIT AREA SUBSTANTIALLY ONLY IN SUCH A QUANTITY AS TO CAUSE SAID REAGENT TO BE SUBSTANTIALLY COMPLETELY REACTED WITHIN THE EMULSION IN THE EVENT OF THE FULL DEVELOPMENT OF THE SILVER HALIDE OF SAID UNIT AREA, SAID REAGENT BEING DISSOLVABLE