US2584029A - Photographic silver transfer product and process, including a lead salt - Google Patents

Description

Jan. 29, 1952 E. H. LAND 2,584,029

PHOTOGRAPHIC SILVER TRANSFER PRODUCT AND PROCESS, INCLUDING A LEAD SALT Filed April 13, 1946 FlG.l

PHOTOSENSITIVE LAYER I O BASE LAY E n IMAGE CARRYING LAY ER I V INVENTOR BY fl ng AT ORNEY Patenied Jan. 29, 1952 PHOTOGRAPHIC SILVER TRANSFER PROD- UCT AND PROCESS, INCLUDING A LEAD SALT Edwin H. Land, Cambridge, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Application April 13, 1946, Serial No. 662,000

29 Claims.

This invention relates to photography and more particularly to novel photographic film units and materials, and methods for utilizing such film units and materials.

More specifically, a preferred form of the present invention relates to improvements over the novel photographic film units and processes disclosed in my copendin-g application Serial No. 576,254 filed February 5, 1945, for Photographic Process, Apparatus and Product, now abandoned. It is, however, not limited to use with such processes or films.

The principal object of the present invention is to provide photographic materials and processes which enable the production of a positive image having increased contrast, gamma and stability.

Another object of the invention is to provide a photographic image having a pH varying in accordance with the density of said image, said pH being high in the shadows and low in the highlights.

Another object of the invention is to provide a composite photographic film unit comprising a photosensitive layer, an image-carrying layer and a container having therein a liquid composition, said liquid composition comprising a solvent for a developer and an alkali, said film unit having therein a developer and an alkali, said imagecarrying layer having associated therewith a substance capable of reducing the alkalinity of said image-carrying layer when said liquid composition is spread in contact therewith.

Another object of the invention is to provide in a photographic process of the type wherein a layer of photosensitive material is treated with a liquid composition, including a developer, and a positive image is created by transferring image forming components from said layer to another layer, the improvement which comprises increasing the contrast and gamma of said image by forming said image in thepresence of a sub stance capable of reducing the alkalinity of said image in the highlights thereof.

A still further object of the invention is to provide a photographic process which comprises treating a layer of exposed photosensitive material with an alkaline liquid composition contain ing a developer, an alkali, and a substance capa ble of forming image-forming components with nents to another layer and creating on said other layer a positive image having dense blacks and clear highlights by reacting said image-forming components. with said alkaline liquid composition and preventing the oxidation of any excess developer in the area of said highlights by reducing the alkalinity of said liquid composition in the area of said highlights to a point where oxidation of said developer does not occur.

A still further object of the invention is to provide a photographic sheet material capable of acting as a carrier for a final positive image when formed into a permeable assembly with an undeveloped exposed photosensitive layer and permeated with a liquid composition containing a solvent, a developer, a material for forming positive image-forming components and a film-forming material, said sheet material having associated therewith a substance capable of reacting with said film-forming material to form therewith compounds less soluble in water than said film-forming material.

These and other objects of the invention will in part be obvious and will in part appear hereinafter.

In one form of the present invention there is provided a composite photographic film unit having a photosensitive layer and another layer. The other layer may serve several functions. In

a preferred example it acts as a backing layer topermit the spreading of. a liquid composition in a layer parallel to the photosensitive layer and it also performsthe additional function of serving as a carrier for the final positive image. In less preferred forms of the invention it serves only either one of these functions or merely acts to carry certain of the reactive ingredients. In a1- most all cases, however, it will have the additional function of forming, with the photosensitive layer, a unit only slowly permeable to oxygen and within which a photographic reaction may take place with substantial freedom from the effects of aerial oxidation. This layer is referred to as an image-carrying layer. Between these two layers there is included a rupturable container or pod having therein a liquid composition. This composition is preferably viscous, preferably alkaline and preferably contains therein a developer and a film-forming material. The liquid composition also preferably contains a substance which will react with the unexposed portions of the photosensitive layer to form therewith soluble image-forming complexes. When the pod is ruptured and the viscous developing composition tion of the film-forming substance which, dur- I 3 ing the processing of the film, is converted from a fluid to a solid. The positive image-forming complexes are transferred from the photosensitive layer to, the image-receiving layer, where the positive image is formed. The photosensitive layer is next preferably stripped from the imagereceiving layer to reveal the finished positive image.

The present invention deals primarily with the improvement of the above process and product by increasing the stability, contrast and gamma of the resultant image and the insolubility and dimensional stability of the formed film. The present invention is not limited to use with-the above product or process, however.

For a fuller understanding of the nature and objects of the invention reference should be had 7 to the following detailed description taken in connection with the accompanying drawings, wherein: 1

Figure 1 isan exaggeratedcross-sectional view of ;a preferred embodiment of -.the present inven-.

tion; and r I Fig. 2 is an exaggerated cross-sectional view of another embodiment of thepresent invention.

As shown in Fig. *1, there is providedxa base layer In adapted to carry on one surface thereof a photosensitive layer H. There is also provided an image-carrying layer [2 which may be joined to the base layer til-by means of a hinge I l. Between-the image-carrying layer 1 2 and the photosensitive layer l i, there is positioned aconloseacetate, cellulose acetate propionate, brother substances capable of supportingalphotosensie tive-emulsion. 7

This base .canbe madeopaque, if desired, by

the addition of suitable dyes or pigments to the above-named substances, or the base. :lllfcan be made or paper and-other.materialssuitable .for supporting a photosensitive emulsionopacity will be preferable depending upon .how the film is exposed within the camera. :It may also be made of an impermeablesubstance.such

asglass.

The photosensitive layer is preferably of the type rendered developable .by exposure .to light, e. g., an emulsion of a silver halide, or ofa mixture of silver halides or of a mixed-:silver halide.

The image-carrying layer H2, in a'preferred embodiment. of the invention, :is Iformed of a photographic material, known in .the artasbaryta paper, although it can be made .of other substances. This layer is preferably pern eableto a substance contained in the liquid composition and may also be manufactured from other sub stances such as gelatin or paper. It may also be made of gelatin, regenerated cellulose, .polye hydroxy alkanes such as polyvinyl .alcohol,'.s,odium alginate, certainof the cellulose etherssuch as methyl cellulose, and their derivatives such as sodiumcarboxymethyl cellulose or hydroxyethyl cellulose, carbohydrates such as gums or starch, and mixtures of these materials where Such 4 v the latter are compatible. It may, however, be made of relatively impermeable materials such as glass, Celluloid and other materials commonly used in the photographic arts.

The liquid composition, in its preferred embodiment, is composed of a developer such as hydroquinone, a film-forming substancefsuch as sodium carboxymethyl cellulose, and a substance adapted to form from a latent photographic image a posi- V tive image-forming component. This latter substance in a preferred form of the invention is sodium thiosulfate. There are also preferably in cluded other substances to aid the photographic -reaction,-such as a preservative, i. e. sodium sulfite, and an alkali, i. e. sodium hydroxide, plus water to carry the abovementioned elements in solution, Suitable liquid compositionsmay be produced as shown in the following nonlimiting examples.

Example #1 The following substances are put in a beaker.

and stirred with ,aplastic rod until dissolved:

Water -cc 47.6 7 Sodium sulfite (desiccated) ;grams, .18 Sodium hydroxide do 117.5

The following substance isthen stirred into'the above mixture with a'plasti'c rod to avoid lumps:

Sodium carboxymethyl cellulosemedium viscos' ity (Lot No. i155 Hercules), 42.62'grams. The above mixture is stirred in a closedjmixer having a nitrogen atmosphere over "the liquid therein, and the temperature is raised .t'ol'TB" The mixture is maintained at this temperature Ex mple #2 The following substances are put in a'beaker and stirred with a plastic rod until dissolved:

. Water cc 476 Sodium sulfite' (desiccated) grams 9 Sodium hydroxide do V 19.50

The following substance'is then stirred into the above mixture with aplastic rod to avoid lumps: Sodium carboxymethyl cellulose, medium viscosity (Lot No. 1155 Hercules),'4;2.62 grams.

The above mixture isstirred in a closed mixer 7 having a nitrogen atmosphere over the. liquid therein, and the temperature is raised to 178 F. The mixture is maintained at this temperature for approximately 3% hours. During the first two hours 2.5 grams of sodium-tliiosulfate are added to the above, mixture. During the last hour of heat treatments grams of hydroquinone are'adde'dto the mixture; 237 cc. of water are I then added to the mixture sometime before the completion'of the '3 /zhour heating period.

Various equivalents maybe used in the above-- mentionedliquid composition and it isequally possible to substitute for the thickening and'film forming sodium carboxymethyl cellulose other film-forming: agents; such as hydroxyethyl cel-.

lulose, or gelatin, or such materials as sodium alginate, or starch. Equally, other developers,

preservatives and alkaliesmay be used, and other substances such as restrainers may beadded.

In the use of the invention as described above,

the photosensitive layer isexposed; to ia'ctinic' light a Ell and, without further exposure to light, the whole assembly is subjected to a mechanical stress such as by passing through a wringer, not shown, starting with the hinge end 14. As the film is squeezed through the wringer, the container [3 is ruptured and the liquid composition is uniformly spread between the photosensitive layer H and the image-carrying layer i2.

When the liquid composition is spread between the photosensitive layer H and the image-carrying layer l2, the following reaction takes place: the developer develops the latent photographic image and the sodium thiosulfate dissolves the unexposed silver halide grains and carries them into the image-receiving layer, being formed by the solidification of the film-forming substance contained in the liquid composition. These unexposed silver halide grains are then developed and formed into a positive image. While this process is in operation stated above, the filmforming substance, i. e. the sodium carboxymethyl cellulose, is being solidified into a dimensionally stable film,

It has been found that it is possible to substantially improve the products and processes described above by increasing the insolubility of the image-receiving layer, increasing the contrast of the positive image, increasing the gamma, increasing the density of the transferred imageforming components, and insolubilizing various unexhausted elements of the liquid composition.

The above can be accomplished by placing preferably within or upon the upper surfac of the image-carrying layer I2 a material which enters into the photographic reaction to bring about the results set forth above. Of the materials which have been found satisfactory, those showing the most extraordinary results are generally the lead salts, and, of the lead salts, lead acetate appears to be the most desirable. In the preferred modification of the invention, imagecarrying layer I2 is coated with a solution of a lead salt such as lead acetate,,ancl the solvent is allowed to evaporate, leaving within and upon the surface of the layer 12 a precipitate of lead acetate. When the above-described photographic process is practiced and the liquid composition is spread between the photosensitive layer II and the lead acetate coated layer l2, the lead acetate is taken into solution by a solvent (water) in the liquid composition, and substantially improves and increases the contrast, gammaand stability of the final positive image. It whitens the highlights and increases the density of the shadows.

All of the reactions involved in this substantial improvement of the quality and stability of the final positive image are not completely understood, and in some cases, it is difficult-to differentiate between cause and effect in the various reactions which are going on simultaneously. There are, however, certain reactions which can be set forth with a considerable degree of certainty. In the first place, it is quite definitely known that the lead acetate reacts with a polymeric substance such as sodium carboxymethyl cellulose to form cross-linkages therewith and thereby create a compound having an increased insolubility in water. This is believed to hasten the precipitation of the film-forming sodium carboxymethyl cellulose, thereby speeding up the formation of the image-receiving layer. The compound resulting from the interaction of the lead acetate and the sodium carboxymethyl cellulose gives a more dimensionally stable film, having an increased insolubility in water.

The lead acetate remarkably increases the con trast and gamma of the positive image produced in the image-receiving layer, although it is not completely understood how this effect is accomplished. There are certain observed conditions which would explain this improvement of the positive image, but the reason for the existence of these conditions is not readily ascertainable from a theoretical analysis of the various reactions. The positive image formed in the presence of lead acetate has very much denser blacks than a positive image formed under exactly the same circumstances wherein lead acetate is not used. This intensification of blacks is believed to be caused by an increase in the amount and size of the silver grains forming the positive image. A remarkable increase in intensification is provided by the use of lead salts generally and lead acetate in particular. It is believed that the lead reaction with the sodium carboxymethyl cellulose changes the character of the film being formed to such an extent that the'silver formed therein is formed in larger grain sizes, whereby a greater density is achieved, and less scattering of light results.

It has also been observed that an image produced without the use of a material such as lead acetate has a more or less overall uniform alkalinity; while an image produced with the use of :lead acetate has a remarkable variation in pH from point to point, and it has been found that those images having th clearest whites and the darkest blacks showed a condition which was slightly acid or neutral, i. e. a pH of 6-8, in the highlights and quite basic, i. e. a pH of above 9, in the shadows. It is believed that this slightly acid or neutral condition plays an extremely important part in at least the preservation of clear whites. One of the reasons for believing this is that those images, lacking clear highlights, are apparently stained by an oxidation product of the developer. Such a stain is eliminated when lead acetate is used in sufiicient quantity to convert the highlights to a slightly acid or neutral con dition. It is believed that this is due to the fact that the developer is incapable of being oxidized in a neutral or slightly acid solution. Therefore, no stain can form even though a potential stainforming component exists in the Whites which is made inactive by the lower pH. The presence of this stain-forming component in the highlights has been experimentally ascertained by taking a positive image, having clear highlights, produced with a lead acetate-coated image-carrying layer and placing a drop of sodium hydroxide on a clear highlight. This sodium hydroxide raises the pH considerably and a brown stain appears.

In the preferred form of the invention, lead acetate is used as the insolubilizing agent. This lead salt seems to be particularly efficient for accomplishing the results mentioned above and is quite easily usable since it is soluble in water.

A preferred method of incorporating the lead acetate in the image-carrying layer I2 is as follows:

1575 grams of lead acetate are dissolved in 3500 cc. of water. shallow container and heated to approximately -90 F. A continuous roll of double-weight baryta paper is then passed over the lea-d acetate bath for approximately two minutes. The paper is suspended near the bath by rollers in such a way that only one surface thereof will contact the bath. Thus, only one surface is coated. After passing through the bath, the paper. is passed This mixture is placed in a ovena dryingdrum "which'isheatedto approximately 75i-I-909 F. The coated surface of: the paper is in contact with the :drum :for approxia mately 'l minutes- This is a preferred method or coating lead acetate 1 upon. double-weight y a paper, but otherimethods may equally be used.

This method of coating the barytapaper is; preferredsince it places the poisonous leadracee 'tateonttheinner surface only of. theimagecarrying layer. Thus, in-the handling of thefilm pack the fingers'xofa-a user 'do not :contact the Of course, when; the film iunit h'as b'een processed in the :manner.

lead acetate-coatedsurface.

describedabova thelead has combined with the materials usediand has formed insoluble salts.

Despite .the'eformation of. these insoluble salts. it is stronglyrecommended that care beusedin-x handlingcthefinished picture, lest some'soluble- The finished picture should lead-salts remain. not: be placed inthe mouth.

In-uvi'ew: of-the factthat lead salts are highly poisonous,.;another preferred former: the present invention embodiesz-xtheuseof .a leadsalt which isinsoluble in water. As an example of this,

thereiisiusemlead tartrate which is deposited uponandiwithin the surface of 'the irnage-carrye ing;:laye1"l2. With: lead .tartrate used in place of a wateresolubleilead'salt, such as lead acetate, the leadtartrate will. not'normally be removed frQmithealayerJZ' by -handling. For instanceit willi'znot beipicked..up..by the fingers of a user' though .thisrlead salt-is insolublein water. It is believed that this eifect is due to the sodium.

hydroxide which apparently dissolves the lead tartrate and: forms therewith insoluble compoundsmore slowly than the other elements of the. combination: thus the lead is in ionic conditionfor reaction with the other elements of the composition.

Numerousother lea'dsalts, such as lead nitrate, lead bromide lead chlorate, lead perchlorate, lead .citrate,;lead. isobutyrate, lead peroxydisulfate,'or lead dithionatemay be used inthe practice-of.-the present invention. The lead salts may. be used singly or jointly; for example, excellent results have' been'obtained with an image-carryi inglayer firsttcoatedwith lead acetate'and'then with leadenitrate.

Since lead-salts are. extremely poisonous, personsworking withthese salts. should u'tilize the nOrmalprecauticns -.-practiced with any use of I lead salts. 7

Someoithese .leadsalts. areinsoluble in Water but solublein other substances. If those solvents are-not normally included in the liquid composition, they-areadded so that the'liquid composi tion will dissolve the lead salt. If it is undesirable to include-this solvent-in combination with the other-elements of the liquid composition for too long a time, a separate container is included ton-carry the solvent;

Zinc acetate 'frnay.. also be usedfor whitening:

' forming material.

the. higl-1lights.-:. This;;materlal:-..may. be .1- placedzl within'andzupon; the surface-rofsthe;imageecarry ingrrlayerx, l 2 in. the same .manner ;as practiced The zinc acetate is also taken intossolution by a solvent 2 therefor con. tainedwin: the liquidvcomposition' and reacts in much thesame-way-except that it doesnot in solubilize the sodium carboxymethyl. cellulose.v

with the lead salts.

It does,;however., whiten-the highlights.

It isq.-believed that. .the beneficialresults. ob-. tained'vwith the zinc acetate are. due v partly to. its ability to-reduce I thealkalinity =inv the neighL- borhoodof. the highlights of the positive image...

Ithas-salsa been .found that. it .is -possible.to practice the present invention by. incorporating; an agent such as alead salt inor upon the lowers surface-of the photosensitive layer... In this in:

s'tance the operation is. the same end, and asthe liquid composition is spread between the photo-.. fsensitiveelayer'. and .the imagesupport layer,.it.}.

issolves the leadsaltfrom the photosensitive. layer andlthe leadsalt acts inthesame manner.

as described above.

When-the lead .saltiis. carriedby the-photosensitivelayer, precautionsshould .be taken. to; insure that the .leadsalt is in. a stratum. separate.

from. the photosensitive..material since the lead salts appeantohave a- .strongdesensitizingeffect on the photosensitive material;

It isialsdpracticable tocarry the agent, such.

as aleadsalt, out of contact with eitherthe photosensitivelayer orthe support layer.

Since the leadjsalt hasa coagulating effect. upon. some .,of the film-forming. materials used in'the present invention, it. is preferred in this embodiment of theinvention. to have the lead salt and a.solvent1thereforcontained in a separate container or.pod.. A means for. accom-,.

plishingthis resultLis-shown in Fig.2 where like numbers correspondto like numbers in .F'ig.v 1 As shown here, a. separate container. I?) may be placed immediately; adjacent the container l3 carrying .the liquid .composition. Thus, when the..film..is. exposed and .processed. byrunning througlra wringer, thelead salt solution is re-. leasediand is spread,along with the liquidlcoma position, between-the photosensitive layer and.

the image-carrying; layer. 7

those. cases where; a. film-forming sub-, stance is used which is nothardened by a lead salt, the .lead salt-has. theability to increase the: contrast-and, gamma: of the final positive, even.

though it'may notinsolubilize any vformed film.

Examples: of such film-forming materials are:

hydroxyethyl cellulose 'and' polyvinyl alcohol.

In someuinstances it is desirable to'practice the'presentinvention: without :the use of .a film-' If 1 such:v be. the case, the=- photographic processfis substantially the same as that. described =above =andi the final positiveimage risformedpn and within the surface of Infsuch 'amodificatlOIlxOf the-invention, the lead salts havea'very the image-carrying :layer.

beneficial. effect upon. the final. image,-. increasing its:stabilitmncontrast. and gamma; Zinc.

acetate. similarly; increases ;the--clearness of the highlights when used jwithwa liquid-composition having vno film-formingmaterial.

Another;v though" less preferred, method of practicing; the present invention -.is to. have oer-r tainof thegmaterials'which are preferably included .in' the-liquid composition-placed elsewherein sthefilm units. For instance, it is;pos: sible to deposit thedeveloper andhypoin solid; form on the iInage-carryingz layer; In this." a

case, the. container might have therein only water or' an aqueous solution of sodium carboxymethyl cellulose.

A This sheet can be placed between the photosensitive layer II and the image-carrying layer 12. Thelayer l2 has thereon an insolubilizing agent such as lead acetate. In this modification of the invention, the container has only therein a solvent, such as water, for the various materials incorporated into the extruded sheet. When the water is spread in contact with this extruded sheet, it dissolves the sheet and the remainder of the process is the same as that discussed in connection with Fig. 1.

One advantage of this last-mentioned modification is that it eliminates the necessity for a liquid container and in this case the film unit may be processed by merely wetting it in a water bath until a sufficient amount of water has been absorbed by the film unit to give the desired concentrated solution of the reactive materials.

It is equally possible to place such an extruded sheet between the base layer in and the photosensitive layer ll, although in this latter case it is desirable to include an additional film-' forming material within the water carried by the container, since it is desirable to form the final positive image in a film created during the process.

It should also be understood that, although the invention has been described in terms of individual film units, it may be practiced with roll films wherein a. plurality of images are produced and the roll film may be treated so as to produce each image separately or all images simultaneously.

The use of soluble lead salts, and specifically lead acetate, in silver halide transfer processes is also disclosed in certain other of my copending applications, such, for example, as Serial No. 700,931, filed October 3, 1946, for Photographic Product and Process, and Serial No. 708,007, filed November 6, 1946, for Photographic Product and Process.

Since certain changes in carrying out the above process, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A photographic product comprising a photographic product comprising a photosensitive material which includes a silver halide layer, a base layer for receiving, by transfer, a positive print, and a rupturable containing means holding a liquid, said product having positioned therein photographic reagents including a silver halide developer, a silver halide solvent and a lead salt soluble in said liquid, said containing means and said layers being i so held together that said containing means is capable, upon rupture, of releasing at least part of its contents to permeate superposed portions of said photosensitive layer and said base layer, said liquid, upon release, rendering said silver halide developer and said silver halide solvent sensitive layer and to form soluble silver complexes with the undeveloped silver halide of said photosensitive layer and, additionally, providing a solution of the lead salt adjacent the surface of the print-receiving area of said base layer in which part at least of the soluble silver complex is reduced to silver to produce the positive print.

2. The product of claim 1 wherein the liquid is a dispersion of a film-forming organic colloid, and the lead salt is capable of reacting with said colloid to give a reaction product less sol-.

uble in said liquid than said colloid.

3. The product of claim 1 wherein the lead salt is lead acetate.

4. The productof claim 1 whereinxthe lead salt is lead tartrate.

5. The product of claim 1 wherein the containing means comprises a single elongated enclosure which contains all of said liquid, and an elongated dispensing lip which parallels said enclosure and is rupturable to provide a passage for said liquid.

6. The product of .claim 1 wherein the containing means comprises a pair of liquid-containing enclosures, each including a rupturable liquid-dispensing lip'zfor providing a passage therefrom to said image-receiving area, the liquid in one of said enclosures comprising a dispersion of the silver halide solvent and the silver halide developer, and the liquid in the other of said enclosures comprising a dispersion of the lead salt.

7. The product of claim 6 wherein the disper sions are solutions.

8. A photographic product comprising a photosensitive silver halide layer, a base layer, and a rupturable container holding a liquid, said layers and said container being attached together so as to permit said layers to be superposed with said container so positioned as to release its liquid for spreading in a film between said layers, the liquid in said container comprising a silver halide developer, a silver halide solvent and an organic film-forming colloid, said base layer having dispersed therein a lead salt soluble at least in part in said liquid.

9. The product of claim 8 wherein the lead salt is located adjacent only that surface of said base layer which adjoins said photosensitive layer when said layers are superposed.

10. The product of claim 8 wherein the solution is an aqueous solution and the organic filmforming colloid dissolved therein is sodium carboxymethyl cellulose, and the sheet support is baryta paper.

11. The product of claim 10 wherein the aqueous solution includes hydroquinone, sodium thiosulfate and sodium hydroxide, and the lead salt is lead acetate.

12. A photographic product capable of forming transfer prints in conjunction with a photosensitive silver halide element, said product comprising a rupturable containing means holding a liquid and a sheet support upon which said containing means is mounted, said sheet support providing an image-receiving area adjacent said containing means onto. which said liquid is spreadable'in athin layer directly from'said containing means, said product carrying a silver halide developer, a silver halide solvent and a leadsa-lt soluble in part at least in said liquid, said reagents and said liquid being sufficient in amount and being so located in relation to said image-recei'vingarea that the spreading of said liquid over said areadisperses silver halideJdeewithvsaid colloid to egiveiax reactionproduct less il! 14. The product; oficlaimdzn wherein. :the lead.

e's'oluble in said liquid than; said: colloid.

salt is leadacetatel il5. "The product ofuclaim. l2 wherein:zthe lead salt is lead tartrate.

taining means comprises a tsingleselongatediem closure V which containsz all of said" liquid, and an elong'ated dispensinglipr. which. parallelsi .said aenclosure and eissrupturahlez. tozprovide aipassage fors s'aid liquid.

I F '17; fThezproduct-bf zclaim .12; wherein ,thecontaining means comprises;a pairrofziliquideconeta-mine enclosures, .eacl'nincludlngcarupturable 'iliquid-jdispensing lip fxfor .zproividing 11a passage 7 ther'efrom to .-vsaid .:image-receiving' 1e'..area,-f.the: illiquid: in ones-(soft:saidziienclosures..z:comprising a ifd-ispersion:aofitheesilvernhalide; solvent' 'and', 'the silveriihalide sdeveloper, .:;and ?the :liquid :in -the :\:-'dther:.-:ofs:;said-.: enclosures :.comprising--:a 'dispersaid 'imagewise distribution' of saidgsoluble 'silver *complex to an image-carrying: :layer':so:super- V posed adjacent said emulsion 'layer as to receive a depthwise diffusion or said solution from saidemulsion" layer without appreciably to silver the silver ions :of said soluble s'ilver complex in the 'presence of' a lead salt soluble saidsolution to form an-image' in silver which =is-a'po'sitive of the-subject matter of said -latent "image.

"24; The process of claim 23 wherein the lead salt iscarried in 's'olidfornr-by saidimage-carryl The:producttofzclaimi'1'7 wherein therdis- V V persions are solutions; :19. miphotographiczproducthcapable of forming transfer prints in conjunctionawvith-aa. photosensitive FISllVel :2 halide element, z'sai'd product e'omprisingea rupturabletcontaining.:means hold- ':ing an: alkalineiliquidzsolutiomofiaacsilver halide l; developer ,:.a .s'ilver halide solventigand' arr: organic -Cfilmeforming::uolloidgtaiid; asheetzzsupport :u'pon twh-ichysaid containing": means .:is: .mounted,: said ei'sheet 'isupport providing; an images-receiving: area adj aeent said: containing means :conto. :which. said -i11quidsolutions. is spreadable gin; a. .thin; layer ,di-

ire'ctlyxirom said: 'containing..:means; :said; support iihaving distributed, 2 at least throughout said.

image-receiving. area,:. a'lead; :s'altsoluble .:in;said z;solution;zsairtisolutiongandcsaidrplead salt being z zsufiicient; in :ramonnt Lsoxth'at: therzspreadingeof :said;;liquid .-'Over:- sa;idaiarea1 provides. a; dispersion of. .rsilverahalidegdeueloper, ::.si1ver ::ha1ide;:- solvent film-forming colloid dissolved-therein issodium ezcar'boxymethyl --.cellulose, and: the sheet support :is 1 barytapaper.

22. The product of :claim ;'21"Wher8in' the aqueous solution 1 includes ehydroquinone, so

iidium. thiosulfate vsand @sodium hydroxide, and

:Ithei lead:1salti.is lead acetate.

23;.Thezprocessiofstorming. positive images .in rrsilver whichicomprisesdeveloping alatent neg- :ative :image. insa silverthalide. emulsion layer swith ax solution-comprising-a. silver halide .de- .1 velopert and l. a: silver: halide solvent: to form an i. imagewise distribution ;of;soluble silver complex ;:in: saidsiemulsionzzlayer, :transferring from said --emulsion1ayer by'z'imbibition at.. ;least. part .Of

inglayer in a position to bedissolvedfin' the solution.

"25."The processpfclainr-Zt-wherein the lead 7 .salt is dispersed adja'centonly' the surface of sensitive layer.

-26.'-The;process of claim=23"wherein a liquid containing an"01'ganic film' forming colloid ;-'-is "spread in a 'layer generaily; parallel to and: ad-

"ja'cent the photosensitive emuision in a' position to permeate said emulsion *and gproVides 'sthe liquid-for the solution' ofthe-silverhalide developer and the silver halide solvent.

7 '27. The process cram-1m 26 wherein'the-liquid is spread-between the, silver halide emulsion layerand the image-carrying' layer, and the "lead saltreacts with the film -forming eolloidin the liquid layer" to form therewith a reaction product more insoluble in the liquid than the colloid.

28. The-process of claim 27' wherein the lead salt is lead acetate.

29; A photographic product 1 capable or form- *ing-tran'sfer prints-in conjunction "with a photo- "sensitive silver" halide element, said "product comprising a rupturable containing means" hold- "ing'a liquid" and" a sheet" support upon-"which said "containing" means is 'mounted, said sheet support" providing 'an.-'-image-receiving area adjacent saidcontaining means 'onto which said liquid is sprea dable in a thin layer directly from "said containing means; said product carrying a lead 'salt -soluble in partat "least in'said liquid and also at leastone substance from the class consisting of the silver halide 1 developers and the silver halide solvents; :said liquid beings-suificient' in tamount and beingi-so located inzrelation -to said image receiving area that 1 the spreading'ofsaidliquidt'over said area disperses :zsaidssubstance and; .leadi'sa'lt throughout ;:said .area'? in adequate quantity..:to:participate in the formation of a transfers-print of aslatent'. image in an area of a contiguous silver'halide. element 2 equivalenttrto said :imageereceiving v area.

."E'D'WIN LAND.

JREFERENCES CITED "iThe following" references are of record 'in" the itle of this patent:

'JUNITED. STATES PATENTS E-Number if Name Date 2312 954 :iBlain ::*Feb..:24,I 1885 1,610,888 itifelley ..'I Dec. '14,; 1926 l',9:lifi';350 :Wendt. July .4,1.:l.933 1 ,963,707 LeJeune :June 19,1934 .5 2,691 639 .rRllSSEll ;:'Aug. 31, 1937 "32,217,169 *Sus Oct." 8,i 1940 123224269 Ivlelntosh 1 Dec. 10,; 19,40

:{vQihCP TBf-CKBHUQS on fcllowingpage) said image-carrying layer-adjacent the photo- 14 Country Date Great Britain May 8, 1930 Great Britain May 12, 1932 Great Britain May 3, 1933 Great Britain July 26, 1934 France Mar. 10, 1943 OTHER REFERENCES Beveridge: Paper Makers Pocket Book," D.

10 Van Nostrand & Company, 1925, page 238 cited.

Wall: Intensification and Reduction, American Photographic Publishing 00., 1927, page 15 Photography Theory and Practice. Pitman Publishing (10., pages 355-? cited 2d edi- UNITED STATES PATENTS Number Number Name Date 3581762 2,224,654 McIntosh Dec. 10, 1940 3 2,637 2,322,005 Fierke June 15, 1943 a 391,790 2,322,006 Fierke June 15, 1943 413,853 2,322,027 Jelley June 15, 1943 879,995 2,352,014 Rott June 20, 1944 2,355,884 McIntosh Aug. 15, 1944 FOREIGN PATENTS Number Country Date 12,678 Great Britain July 22, 1899 of 1 99 cited 1311).).

10,051 Great Britain Apr. 30, 1906 Clerc- 24,667 Great Britain 1906 15 u 1937 13,835 Great Britain 190*! 1

Claims (2)

1. A PHOTOGRAPHIC PRODUCT COMPRISING A PHOTOGRAPHIC PRODUCT COMPRISING A PHOTOSENSITIVE MATERIAL WHICH INCLUDES A SILVER HALIDE LAYER, A BASE LAYER FOR RECEIVING, BY TRANSFER, A POSITIVE PRINT, AND A RUPTURABLE CONTAINING MEANS HOLDING A LIQUID, SAID PRODUCT HAVING POSITIONED THEREIN PHOTOGRAPHIC REAGENTS INCLUDING A SILVER HALIDE DEVELOPER, A SILVER HALIDE SOLVENT AND A LEAD SALT SOLUBLE IN SAID LIQUID, SAID CONTAINING MEANS AND SAID LAYERS BEING SO HELD TOGETHER THAT SAID CONTAINING MEANS IS CAPABLE, UPON RUPTURE, OF RELEASING AT LEAST PART OF ITS CONTENTS TO PERMEATE SUPERPOSED PORTIONS OF SAID PHOTOSENSITIVE LAYER AND SAID BASE LAYER, SAID LIQUID, UPON RELEASE, RENDERING SAID SILVER HALIDE DEVELOPER AND SAID SILVER HALIDE SOLVENT EFFECTIVE TO DEVELOP A LATENT IMAGE IN SAID PHOTOSENSITIVE LAYER AND TO FORM SOLUBLE SILVER COMPLEX WITH THE UNDEVELOPED SILVER HALIDE OF SAID PHOTOSENSITIVE LAYER AND, ADDITIONALLY, PROVIDING A SOLUTION OF THE LEAD SALT ADJACENT THE SURFACE OF THE PRINT-RECEIVING AREA OF SAID BASE LAYER IN WHICH PART AT LEAST OF THE SOLUBLE SILVER COMPLEX IS REDUCED TO SILVER TO PRODUCE THE POSITIVE PRINT.

23. THE PROCESS OF FORMING POSITIVE IMAGES IN SILVER WHICH COMPRISES DEVELOPING A LATENT NEGATIVE IMAGE IN A SILVER HALIDE EMULSION LAYER WITH A SOLUTION COMPRISING A SILVER HALIDE DEVELOPER AND A SILVER HALIDE SOLVENT TO FORM AN IMAGEWISE DISTRIBUTION OF SOL,UBLE SILVER COMPLEX IN SAID EMULSION LAYER, TRANSFERRING FROM SAID EMULSION LAYER BY IMBIBITION AT LEAST PART OF SAID IMAGEWISE DISTRIBUTION OF SAID SOLUBLE SILVER COMPLEX TO AN IMAGE-CARRYING LAYER SO SUPERPOSED ADJACENT SAID EMULSION LAYER AS TO RECEIVE A DEPTHWISE DIFFUSION OF SAID SOLUTION FROM SAID EMULSION LAYER WITHOUT APPRECIABLY DISTURBING THE IMAGEWISE DISTRIBUTION OF THE SILVER COMPLEX IN SAID SOLUTION, AND REDUCING TO SILVER THE SILVER IONS OF SAID SOLUBLE SILVER COMPLEX IN THE PRESENCE OF A LEAD SALT SOLUBLE IN SAID SOLUTION TO FORM AN IMAGE IN SILVER WHICH IS A POSITIVE OF THE SUBJECT MATTER OF SAID LATENT IMAGE.

Images