US3644116A

US3644116A - Identification cards having diffusion transfer laminations

Info

Publication number: US3644116A
Application number: US618685A
Authority: US
Inventors: Paul A Andrews; Bernard T Coyle Jr
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1967-02-27
Filing date: 1967-02-27
Publication date: 1972-02-22
Anticipated expiration: 1989-02-22

Abstract

Laminar structures comprising a photographic image in silver laminated to a transparent layer through or via a layer comprising a water-activated plasticized vinyl acetate polymer.

Description

United States Patent Andrews et a1.

[ 5] Feb. 22, 1972 [54] IDENTIFICATION CARDS HAVING DIFFUSION TRANSFER LAMINATIONS [72] Inventors: Paul A. Andrews, Belmont; Bernard T.

Coyle, Jr., Marblehead, both of Mass.

[52] 11.8. C1 ..96/29, 40/22, 96/76, 117/72 [51] Int. Cl ..G03c 5/54 [58] Field ofSearch ..96/69, 76, 79, 29; 117/34; 161/5, 6, 76

[56] References Cited UNITED STATES PATENTS 2,361,670 10/ 1944 Whitehead ..40/2.2 2,558,857 7/1951 Land ....96/29 2,719,791 10/1955 Land 2,956,877 10/ 1960 Land et al ..96/29 3,113,866 12/1963 Land ..96/94 3,204,354 11/1965 Berger ...40/2.2

3,219,445 11/1965 Lu Valle et a1. ..96/76 3,313,052 4/1967 Malster ....40/2.9

3,152,901 10/1964 Johnson ..96/27 OTHER PUBLICATIONS 1. Skeist, Handbook of Adhesives, Reinhold Publishing Corp. N.Y., 1962. pps. 373- 75, 574- 76 relied upon.

Primary Examiner-Norman G. Torchin Assistant Examiner-John L. Goodrow AttorneyBrown and Mikulka, Stanley H. Mervis and Alvin lsaacs [57] ABSTRACT Laminar structures comprising a photographic image in silver laminated to a transparent layer through or via a layer comprising a water-activated plasticized vinyl acetate polymer.

14 Claims, 3 Drawing figures PATENTEBFB22 m2 FIGE ' INVENTORS PM Mm ATTORNEYS IDENTIFICATION CARDS HAVING DIFFUSION TRANSFER LAMINATIONS This invention relates to a novel and improved card that serves to identify its holder.

It is one object of the present invention to provide an identification card, or the like, which comprises a photographic likeness of its holder.

A further object of the present invention is to providean identification card, or the like, which bears a photographic likeness of its holder and which will automatically be defaced by or will automatically reveal any attempt to change or alter said photographic likeness.

A further object of the present invention is to provide an identification card of the type described above which is durable and which will provide a long and useful service life.

A further object of the present invention is to provide novel laminations comprising photographic likenesses which cannot be separated without destroying said photographic likenesses.

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

The invention accordingly comprises the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties, and relation of elements 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 of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

E16. 1 is a cross section, greatly magnified, of one stage in the preparation of a lamination made in accordance with this invention;

FIG. 2 is a cross section, greatly magnified, of a completed lamination made in accordance with this invention; and

FIG. 3 is an illustration of one method of preparing the laminations of this invention.

Numerous cards have been proposed which are designed to identify their holders to others. Typical examples are the socalled Credit Cards provided by various commercial enterprises, such as department stores, service stations, and the like, automobile driver's licenses, and identification badges such as those used to identify the personnel of plants or buildings where employees are limited in their right of access to predetermined portions of the plant or building.

In such instances, it is of great importance to provide persons with an identification card or badge which is difficult or impossible to counterfeit and which immediately identifies its holder or wearer, preferably by containing a photographic likeness of him. 1n particular, it is highly desirable to provide a card or badge which comprises a photographic likeness of its holder together with any other desired identifying indicia, which card or badge is laminated to a transparent rigid or semirigid film by way of a so-called security seal, that is, a seal which cannot be broken or tampered with without immediately clearly rendering the intrusion obvious by destroying or defacing the photographic likeness.

Where the identification card contains a photographic likeness of its holder, it is desirable, in the interest of speed and efficiency, to provide a rapid means of obtaining such a likeness. Of particular advantage in this respect are silver transfer images of the type which may be produced by applying a processing composition containing a silver halide developing agent and a silver halide solvent to a photoexposed photosensitive silver halide element and an image-receptive element that are in superimposed relation. The processing composition acts to reduce exposed silver halide to silver, to react with unreduced silver halide to form a water-soluble complex silver salt, and to transfer it to the image-receptive element where it is reduced to silver.

Examples of photographic materials useful in the production of the foregoing type of photographic silver images are described in detail in U.S. Pat. No. 2,543,181, issued in the name of Edwin H. Land on Feb. 27, 1951, and in U.S. Pat. No. 2,647,056 issued in the name of Edwin H. Land on July 23, 1953.

In a typical process employing such materials, a processing composition containing a viscous aqueous solution of a silver halide developing agent, a silver halide solvent and an alkali is spread in a uniformly thin layer between the superposed surfaces of the photoexposed gelatino silver halide stratum of a photosensitive element and the silver-receptive stratum of an image-receptive element. The elements are maintained in superposed relation for a predetermined period ordinarily of approximately 10 to seconds in duration, during which exposed silver halide is reduced to silver and unreduced silver halide forms a water-soluble complex silver salt which diffuses through the layer of composition to the image-receptive stratum, where, upon being reduced to silver, it forms a silver print. At the end of this period, the photosensitive element, preferably together with the solidified layer of processing composition, is stripped from the image-receptive element.

Image-receptive strata of the foregoing type include silverprecipitating nuclei dispersed in a macroscopically continuous vehicle comprising submacroscopic agglomerates of minute particles of a water-insoluble inorganic, preferably siliceous material such as silica aerogel. Silver grains precipitated in the foregoing manner are concentrated primarily at the surface of the stratum. This stratum, both before and after receiving these precipitated silver grains, is extremely thin, preferably being approximately 1 to 8 microns thick. Materials of the foregoing type are specifically described in U.S. Pat. Nos. 2,698,237 and 2,698,245 issued to Edwin H. Land on Dec. 28, 1954.

The foregoing process is particularly adapted for use in a Polaroid Land camera made by Polaroid Corporation, Cambridge, Massachusetts 02139, or a similar camera structure such for example, as the camera forming the subject matter of U.S. Pat. No. 2,435,717, issued to Edwin H. Land on Feb. 10, 1948.

Where photographic likenesses of individuals are desired for identification card purposes, the foregoing process when used in cameras of the aforementioned type renders it possible to obtain such likenesses immediately upon making the photographic exposure, and obviates the necessity of the usual waiting period required for conventional photographic processes wherein a negative must be photoexposed and developed in a separate subsequent operation. However, owing to the nature of the image-receptive element as described above, it has been found that where it is sought to laminate the final silver transfer image to any conventional transparent supporting material, the image layer tends to separate, or be easily separable from the transparent overlay. This was found to be particularly true when laminations were sought to be made between the silver transfer image and various transparent supports using pressure-sensitive adhesives.

It has been found that excellent security seals can be provided for silver transfer images of the aforementioned type by laminating such images to transparent layers which comprise a hydroxylated polymer, preferably a polyvinyl alcohol, modified polyvinyl alcohol, or hydrolyzed cellulose ester, which layer may have a suitable transparent backing if desired, via an intermediate layer comprising a plasticized vinyl acetate polymer.

In particular, it has been found that vinyl acetate polymers containing plasticizers which render them water-activatable" can be used to provide coatings for hydroxylated polymer surfaces of the aforementioned type, which coatings when dried, can be subsequently rewetted with water to provide efficient adhesive layers between the hydroxylated polymer surfaces and superposed siliceous silver transfer image-bearing surfaces. The term water-activatable, when used with respect to plasticized vinyl acetate polymers in connection with the instant invention, is intended to mean that by merely applying water to the dried plasticized vinyl acetate polymer layer (which is ordinarily devoid of tackiness), the layer is rendered pressure-sensitive to the extent that upon the application of pressure alone, the layer can be made to adhere to silver transfer images of the type described above. It should be noted in this regard that in order to be water-activatable, the plasticized vinyl acetate polymer need not be water-soluble. As examples of plasticized vinyl acetate polymers which may be used as adhesive layers for lamination within the scope of the instant invention, mention may be made of vinyl acetate/maleate copolymer plasticized with n-butyl acetyl ricinoleate and vinyl acetate homopolymer or copolymer plasticized with dibutyl phthalate.

As examples of hydroxylated polymers which may be used as transparent layers for bonding to silver transfer images to form the laminations of this invention, mention may be made of polyvinyl alcohol; oriented, light-polarizing polyvinyl alcohol-polyvinylene, oriented polyvinyl alcohol containing dichroic dyes, vinyl alcohol-containing copolymers such as partially hydrolyzed polyvinyl acetate; partially hydrolyzed vinyl acetate-vinyl chloride copolymers; polyvinyl alcohol with various subcoats such as cellulose nitrate and/or cellulose esters, and hydrolyzed cellulose esters such as hydrolyzed cellulose acetate.

The plasticized vinyl acetate polymer is preferably coated upon the support from solution, following which the coating is permitted to dry. in the dried state the coated material is stable and may be stored for extended periods of time prior to its actual use in a lamination with a silver transfer image.

In preparing coating solutions for the laminations of this invention, the plasticized vinyl acetate polymer may simply be dissolved in an organic solvent such as ethanol or isopropanol, and the resulting solution then mixed with water. The concentration of the coating solution is not critical; ideally, it should be such that a single coating of the solution results in a polymer layer of sufficient thickness to give a good bond but which does not result in a solution of unduly high viscosity from a mechanical handling standpoint. it has been found that solutions resulting in a coating having a thickness of about 0.6 mil.i0.l mil. have been particularly satisfactory in this respect.

It has been found that where the coating solution consists essentially of plasticized vinyl acetate polymer of the type previously described, while satisfactory security seals between hydroxylated polymeric surfaces and silver transfer images are provided, the dried coating on the hydroxylated polymer surface prior to lamination may exhibit a high degree of tackiness. If it is desired to reduce or eliminate this particular proparty, a portion of the plasticized vinyl acetate polymer in the coating solution may be replaced with polyvinyl acetate which is plasticized with a material which is nontacky and which does not render the polyvinyl acetate with which it is incorporated tacky; a preferred material for this purpose is polyvinyl acetate plasticized with dibutyl maleate. It has been found that where about percent of the water-activatable plasticized vinyl acetate polymer is replaced by dibutyl maleate-plasticized polyvinyl acetate in the coating solution, the tackiness of the dried coating is substantially reduced; where about half of the water-activatable plasticized vinyl acetate polymer is replaced by dibutyl maleate-plasticized polyvinyl acetate, the resulting coating when dried may be characterized as being essentially nontacky. In general, up to about half of the water-activatable plasticized vinyl acetate polymer in the coating solution may be replaced by vinyl acetate having other plasticizers such as dibutyl maleate without any substantial loss in the strength of the ultimate lamination.

In a preferred embodiment of this invention, the coating includes a minor amount, i.e., up to about 10 percent, of polyvinyl alcohol. It has been found that laminations prepared using such solutions tend to be somewhat stronger than without polyvinyl alcohol; moreover, they exhibit a tendency to set" more readily. However, where polyvinyl alcohol is included, the dried coating on the hydroxylated polymeric overlay prior to lamination exhibits an undesirable degree of tackiness. This can be remedied by replacing part of the water-activatable plasticized vinyl acetate polymer with dibutyl maleateplasticized polyvinyl acetate as described above. In coating solutions including both dibutyl maleate-plasticized polyvinyl acetate and polyvinyl alcohol, care should be taken that the ultimate dried coating contain no less than about 40 percent by weight water-activatable plasticized vinyl acetate polymer.

It is to be noted that the tendency toward tackiness of the Water-activatable plasticized vinyl acetate polymer referred to above has little or no effect upon the security seal ultimately formed, and hence, actually need be taken into account only in those instances where it is desired to prepare coated hydroxylated polymeric overlays and store the overlays for a finite period prior to their use in a security lamination or to provide the overlay as a continuous sheet in rolled form. It will be obvious that where security-sealed laminations between silver transfer images and hydroxylated polymeric surfaces are desired to be made immediately following the coating and drying of the overlay, precautions to minimize or eliminate tackiness are for the most part unnecessary.

Materials which have been found to be particularly efficacious in providing the coating solutions and layers referred to above are the series of resins commercially available from Compo Chemical Company Division of Compo Shoe Machinery Corporation, Roberts Road, Waltham, Massachusetts, 02154, under the trade name XL resins, 700 series, and may be designated as consisting essentially of plasticized vinyl acetate polymers dissolved in isopropanol and water. A particularly useful detackifying material is the resin commercially available from Dewey and Almy Company Chemical Division of W. R. Grace & Co., Cambridge, Massachusetts, 02140, under the trade name Daratak A, and may be designated as consisting essentially of a solution of polyvinyl acetate internally plasticized with 20 percent dibutyl maleate, and a minor amount of a wetting agent.

When it is desired to prepare the final lamination with the silver transfer image, the dried plasticized polyvinyl acetate coating must be activated with water. This can be achieved either by wetting the coated surface, or by wetting the silver transfer print surface. Finally, the silver transfer print and coated surface are placed in face-to-face relationship and pressed together. High pressures are not necessary to achieve the security bond, but may aid in the exclusion or expulsion of any air which may be trapped between the layers.

Extremely thin photographic silver images of the type described above have been found to retain traces of the photographic reagents with which they have been processed, and the continued presence of which has been found to adversely affect their stability. Thus, in the past, it has been found desirable to physically wash such prints and coat them with a protective film-forming material. In the practice of this invention, it isstill preferable that the silver transfer print be washed prior to its lamination. However, it has been found that if the lamination is achieved by feeding the print to be laminated along with the coated transparent material and a drop of activating solution between two rolls ordinarily known as V-ing rolls," a bead of activating solution forms at the nip which effectively washes the silver transfer image. After the aqueous bead has passed over the surfaces being laminated it is ultimately extruded, carrying with it the undesired residue of the developing composition and thus a separate washing step is not necessary. However, where the silver transfer print and the coated transparent hydroxylated polymeric overlay are simply placed in face-to-face relationship and pressure applied directly, it is preferred that the silver transfer image first be washed with water. Where the silver transfer print is washed immediately prior to lamination, it need not be dried; the aqueous washing fluid remaining on the surface of the print in such instances may then also provide the activating solution for the plasticized polyvinyl acetate coating.

An alternate procedure may be used for washing and laminating silver transfer images of the aforementioned type,

which procedure is particularly adapted to those instances where it is unnecessary or inexpedient to prepare the transparent hydroxylated polymer overlay in advance by coating it with plasticized polyvinyl acetate and allowing the coating to dry. In this alternate procedure, an aqueous solution of plasticized polyvinyl acetate is used to simultaneously coat and wash the silver transfer image, and while the coating thus applied is still fresh and wet, the print is pressed directly against the transparent hydroxylated polymer overlay. Suitable devices and processes for simultaneously washing and coating silver transfer prints are described in U.S. Pat. No. 2,768,403 issued Oct. 30, 1956 to Charles A. Govatsos, and in U.S. Pat. No. 2,963,953, issued Dec. 13, 1960 to Donald R. Bishop et a1. While the bonds between the silver transfer prints and transparent overlays are equally satisfactory to those prepared by the first-described procedure, the latter procedure requires the availability, not simply of water, but rather, of aqueous solutions of the polymeric coating material. Where the laminating technique is desired for use as a relatively simple means for the production of tamperproof identification cards or badges, the disadvantages of the latter procedure are obvious.

An additional suitable method for simultaneously providing the water-activatable plasticized vinyl acetate polymer coating and washing the silver transfer print and laminating the prints to an overlay is described in U.S. Pat. No. 2,798,021, issued July 2, 1957 to Edwin H. Land. In this procedure, the coating material is contained in a sealed rupturable container which when ruptured by a suitable pressure-applying means such as pressure-applyingrollers, discharges its contents; means are provided for spreading the contents between the surfaces being laminated. It is to be noted that the procedure described in the last-mentioned patent can also be employed in the lamination of silver transfer prints to hydroxylated polymer surfaces which have previously been coated with the vinyl acetate polymer as described above. In such a case, the rupturable container contains only activating solution (e.g., water) rather than a vinyl acetate solution.

Where the transparent hydroxylated polymeric overlay comprises a light-polarizing material, a second security feature is added to the final laminated photographic image, in addition to that provided by the security bond. Any attempt to tamper with or otherwise alter the surface of the laminate, e.g., by cutting into the material or heating it, affects the lightpolarizing properties of the surface to the extent that the attempted alteration or intrusion can be readily detected with a suitable light-polarizing analyzer. The use of transparent lightpolarizing sheets as a security feature for laminates is described and claimed in the U.S. Pat. application of Robert Malster, Ser. No. 451,895 filed Apr. 29, 1965, now U.S. Pat. No. 3,313,052.

Additionally, if desired, the overlay may include a pattern, such as a stripe, comprising a mixture of dichroic dyes in an oriented polymeric substrate, such as a mixture of a positive dichroic dye of a first color and a negative dichroic dye of a second, distinct color; when viewed through a light-polarizing device, laminations of this type exhibit the original colors of the dyes comprising the mixture, as well as that of the mixture itself, thereby conferring an additional security feature upon the lamination as a whole. The use of mixtures of dichroic dyes to provide security features for information-bearing surfaces is disclosed and claimed in the copending application of Phoebe F. Jordan and Harold O. Buzzell, Ser. No. 513,046, filed Dec. 10, 1965, now U.S. Pat. No. 3,391,479.

Referring now to the drawing, FIG. 1 represents the layers as described above immediately prior to lamination, comprising a silver transfer image layer 8, a transparent hydroxylated polymer overlay on which a layer 9 comprising a water-activatable plasticized vinyl acetate polymer has been coated and allowed to dry. A drop or bead of aqueous activating solution 11 has been placed between silver transfer image layer 8 and layer 9 which, when spread between the layers, activates layer 9, enabling it to adhere to the silver transfer image layer 8 in a security bond.

rotatably mounted and suitably driven in directions indicated by the arrows.

Rolls

12 and 13 are adjustable with respect to the distances between centers so that a suitable pressure may be brought to bear upon the contacting surfaces of the sheets. Numeral l1 designates an aqueous bead of activating solution maintained at the nip between the two sheets of material undergoing lamination adjacent to the point of contact. As described previously, as the aqueous bead 11 is forced by the rotation of

rolls

12 and 13 over the surfaces of the layers being laminated and is extruded from between the layers at the completion of the lamination, it not only activates the plasticized vinyl acetate polymer coating 9 but also effects a washing of the silver transfer image 8. As the completed lamination passes from

rolls

12 and 13, it is characterized by the presence of security bond 18 which is formed between

layers

8 and 9.

The following nonlimiting examples further illustrate the present invention.

EXAMPLE I A sheet comprising a cellulose acetate butyrate support, subcoated with cellulose nitrate, followed by a layer of cellulose nitrate and polyvinyl acetate, and lastly, a layer of polyvinyl alcohol, was coated on its polyvinyl alcohol surface with an adhesive solution comprising a vinyl acetate/maleate copolymer emulsion in isopropanol and water (containing 60 percent solids) and plasticized with about 5 percent n-butyl acetyl ricinoleate, commercially available from Compo Chemical Company under the trade name XL740; a sufficient coating was applied to provide a layer having a thickness of about 0.6 mil. when dry.

After the last-mentioned coating had dried, it was wetted with water and pressed onto the siliceous image-bearing sur face of a silver transfer photographic print of the type previously described, by being passed through a pair of pressureapplying rollers. After a period of about 5 minutes, several attempts were made to separate the photographic print from the overlay; it was found that the image surface of the print adhered firmly to the overlay and could not be separated therefrom.

Cellulose acetate butyrate films having subcoats as described above may be prepared in accordance with the teachings contained in U.S. Pat. No. 2,362,580, issued Nov. 14, 1944, to Gale F. Nadeau and Clemens B. Starck; U.S. Pat. No. 2,541,478, issued Feb. 13, 1951, to the same inventors and U.S. Pat. No. 2,835,609, issued May 20, 1958, to Clemens B. Starck, Gale F. Nadeau, and Carl F. Smith.

EXAMPLE II The procedure of Example I was followed, except that the adhesive solution employed was a vinyl acetate copolymer emulsion in isopropanol and water plasticized with dibutyl phthalate, containing about 48.8 percent resin and 15.8 percent plasticizer, commercially available from Compo Chemical Company under the trade name XL-72l-2;" the resin was identified by infrared spectrophotometry as a vinyl acetate copolymer commercially available from Dewy and Almy Chemical Division of W. R. Grace & Co. under the trade name Everflex." It was observed that prior to lamination to the silver transfer image, the dried adhesive layer was somewhat less tacky than was the layer of Example I. The final lamination was substantially identical in physical properties to that of Example I.

EXAMPLE Ill The procedure of the foregoing examples was followed, except that the adhesive employed was a mixture of polyvinyl acetate (commercially available from Monsanto Chemical Company under the trade name Gelva V-lOO) and dibutyl phthalate in an ethanol/water mixture containing about 49 percent polymer and 16 percent plasticizer. The dried adhesive coating and resulting lamination were substantially identical in physical properties to those of Example II.

EXAMPLE IV The procedure of the foregoing examples was followed, except that the adhesive solution employed was a blend of parts of XL 721-2 solution described above, and 5 parts of an aqueous dispersion of polyvinyl acetate internally plasticized with 20 percent dibutyl maleate, commercially available from Dewey and Almy Chemical Division of W. R. Grace & Co., under the trade name Daratak A. The adhesive coating after drying prior to water activation exhibited a lower degree of tackiness than the adhesive coatings of examples I through Ill.

The final lamination exhibited a seal which was substantially identical to those of the laminations of the foregoing examples.

EXAMPLE V The procedure of the foregoing examples was followed, except that the adhesive solution employed was a blend of 8 parts of XL 72l2 solution and 2 parts ofa 10 percent aqueous solution of 88 percent hydrolyzed polyvinyl alcohol. The resulting lamination was substantially identical to that of the foregoing examples but in addition, was noted to exhibit a particularly high degree of water resistance EXAMPLE VI The procedure of the foregoing examples was followed, except that the adhesive solution employed consisted of a mixture of 45 parts XL 740, 50 parts Daratak A, and 5 parts of the polyvinyl alcohol solution described in Example V. The dried adhesive coating prior to water activation was relatively nontacky; the resulting lamination exhibited an excellent security seal between the silver transfer image-bearing surface and the hydroxylated polymeric overlay.

EXAMPLE VII The procedure of the foregoing examples was followed, except that the adhesive solution employed consisted of a mixture of 50 parts XL 721-2, 40 parts Daratak A, and 10 parts of the polyvinyl alcohol solution previously described. The dried adhesive coating prior to water activation, and the final lamination, were substantially identical to those of Example Vl.

After initial attempts to separate the laminations of each of the foregoing proved unsuccessful, the laminations were stored at 100 percent relative humidity at 100 F. for 10 days; no change was observed either in the lamination bond or in the silver transfer image itself.

it will be appreciated that the term image as used in the foregoing discussion is intended to include not only photographic likenesses of given individuals, but also, especially when applied to identification cards and the like, includes photographically recorded indicia which may form a part of the final picture.

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

What is claimed is:

1. A laminar structure comprising a first transparent layer at least one surface of which comprises a transparent hydroxylated polymer selected from the group consisting of polyvinyl alcohols, at least partially hydrolyzed vinyl acetate-vinyl chloride copolymers, at least partially hydrolyzed polyvinyl acetate, and at least partially hydrolyzed cellulose esters, a second layer adjacent to said hydroxylated polymer surface comprising a water-activated plasticized vinyl acetate polymer, and a third layer comprising a siliceous surface containing a silver transfer image, which third layer is bonded to said first layer via said second layer.

2. A laminar structure as defined in claim 1 wherein said transparent hydroxylated polymer is polyvinyl alcohol.

3. A laminar structure as defined in claim 1 wherein said transparent hydroxylated polymer is a molecularly oriented light-polarizing polyvinyl alcohol.

4. A laminar structure as defined in claim 1 wherein said first transparent layer comprises a cellulose acetate butyrate support having a first subcoat comprising cellulose nitrate, a second subcoat comprising cellulose nitrate and hydrolyzed polyvinyl acetate, and a third subcoat comprising polyvinyl alcohol.

5. A laminate structure as defined in claim 1 wherein said water-activatable plasticized vinyl acetate polymer is a vinyl acetate polymer plasticized with dibutyl phthalate.

6. A laminar structure as defined in claim 1 wherein said second layer includes polyvinyl acetate plasticized with dibutyl maleate.

7. A laminar structure as defined in claim 1 wherein said second layer includes up to about 10 percent polyvinyl alcohol.

8. The process for preparing a laminar structure which comprises coating a transparent sheetlike element at least one surface of which comprises a transparent hydroxylated polymer selected from the group consisting of polyvinyl alcohols, at least partially hydrolyzed vinyl acetate-vinyl chloride copolymers, at least partially hydrolyzed polyvinyl acetate, and at least partially hydrolyzed cellulose esters, with an aqueous dispersion of a water-activatable plasticized vinyl acetate polymer, said coating being applied to said hydroxylated polymeric surface of said transparent layer, drying the coating formed thereby, wetting the surface of said coating with water, and pressing said activated coating on to the siliceous, imagebearing surface of a silver-transfer photographic print.

9. The process as defined in claim 8 wherein said transparent hydroxylated polymer is polyvinyl alcohol.

10. The process as defined in claim 8 wherein said transparent hydroxylated polymer is a molecularly oriented lightpolarizing polyvinyl alcohol.

11. The process as defined in claim 8 wherein said transparent sheetlike element comprises a cellulose acetate butyrate support having a first subcoat comprising cellulose nitrate, a second subcoat comprising cellulose nitrate and hydrolyzed polyvinyl acetate, and a third subcoat comprising polyvinyl alcohol.

12. The process as defined in claim 8 wherein said water-activatable plasticized vinyl polymer is a vinyl acetate polymer plasticized with dibutyl phthalate.

13. The process as defined in claim 8 wherein said aqueous dispersion of a water-activated plasticized vinyl acetate polymer includes polyvinyl acetate plasticized with dibutyl maleate.

14. The process as defined in claim 8 wherein said aqueous dispersion of a water-activatable plasticized vinyl acetate polymer includes a minor amount of polyvinyl alcohol.

Claims

2. A laminar structure as defined in claim 1 wherein said transparent hydroxylated polymer is polyvinyl alcohol.
3. A laminar structure as defined in claim 1 wherein said transparent hydroxylated polymer is a molecularly oriented light-polarizing polyvinyl alcohol.
4. A laminar structure as defined in claim 1 wherein said first transparent layer comprises a cellulose acetate butyrate support having a first subcoat comprising cellulose nitrate, a second subcoat comprising cellulose nitrate and hydrolyzed polyvinyl acetate, and a third subcoat comprising polyvinyl alcohol.
5. A laminate structure as defined in claim 1 wherein said water-activatable plasticized vinyl acetate polymer is a vinyl acetate polymer plasticized with dibutyl phthalate.
6. A laminar structure as defined in claim 1 wherein said second layer includes polyvinyl acetate plasticized with dibutyl maleate.
7. A laminar structure as defined in claim 1 wherein said second layer includes up to about 10 percent polyvinyl alcohol.
8. The process for preparing a laminar structure which comprises coating a transparent sheetlike element at least one surface of which comprises a transparent hydroxylated polymer selected from the group consisting of polyvinyl alcohols, at least partially hydrolyzed vinyl acetate-vinyl chloride copolymers, at least partially hydrolyzed polyvinyl acetate, and at least partially hydrolyzed cellulose esters, with an aqueous dispersion of a water-activatable plasticized vinyl acetate polymer, said coating being applied to said hydroxylated polymeric surface of said transparent layer, drying the coating formed thereby, wetting the surface of said coating with water, and pressing said activated coating on to the siliceous, image-bearing surface of a silver-transfer photographic print.
9. The process as defined in claim 8 wherein said transparent hydroxylated polymer is polyvinyl alcohol.
10. The process as defined in claim 8 wherein said transparent hydroxylated polymer is a molecularly oriented light-polarizing polyvinyl alcohol.
11. The process as defined in claim 8 wherein said transparent sheetlike element comprises a cellulose acetate butyrate support having a first subcoat comprising cellulose nitrate, a second subcoat comprising cellulose nitrate and hydrolyzed polyvinyl acetate, and a third subcoat comprising polyvinyl alcohol.
12. The process as defined in claim 8 wherein said water-activatable plasticized vinyl polymer is a vinyl acetate polymer plasticized with dibutyl phthalate.
13. The process as defined in claim 8 wherein said aqueous dispersion of a water-activated plasticized vinyl acetate polymer includes polyvinyl acetate plasticized with dibutyl maleate.
14. The process as defined in claim 8 wherein said aqueous dispersion of a water-activatable plasticized vinyl acetate polymer includes a minor amount of polyvinyl alcohol.