EP0416019A4

EP0416019A4 - Method and apparatus for mounting photographic prints

Info

Publication number: EP0416019A4
Application number: EP19890906674
Authority: EP
Inventors: Attila Kiraly
Original assignee: EBOND AUSTRALASIA Pty Ltd
Current assignee: EBOND AUSTRALASIA Pty Ltd
Priority date: 1988-05-27
Filing date: 1989-05-26
Publication date: 1991-08-07
Also published as: WO1989011681A1; EP0416019A1; KR900702417A

Abstract

A photographic print (10) is supported and protected from the environment by being mounted on a transparent, substantially rigid, acrylic sheet (12). A layer (11), about 0.2 mm thick, of an acrylic resin is applied to the acrylic sheet and the emulsion side of the print is placed on this layer. A second layer (13) of acrylic resin is applied to the back of the print, to completely encapsulate the print between the two layers. The applied acrylic layers are subsequently cured. The resin layers may be applied from nozzles (30, 33) and spread to the required thickness using at least one roller (20). In automated equipment, the nozzles move reciprocally parallel to the acrylic sheet. The same mounting technique can be effected by placing the print on an acrylic sheet (48) within an envelope (53). The envelope also contains two elongate pods (51), made from a material which is opaque to ultraviolet radiation, which are mounted on one end of the acrylic sheet. Each pod contains a flowable, one-component, ultraviolet curable, acrylic resin which is squeezed from a ruptured line of weakness (52) in the pod and is spread over and under the print when the envelope is passed through a pair of rollers (50).

Description

TITLE: "METHOD AND APPARATUS FOR MOUNTING PHOTOGRAPHIC PRINTS"

TECHNICAL FIELD

This invention concerns the display of photographs. More particularly, it concerns the mounting of photographic prints behind sheets of transparent acrylic material - such as sheets of "Plexiglass"

(trade mark) material. Note that in this specification, including the claims, the term "photographic prints" will be regarded as including within its scope: photographic transparencies, paintings, posters, and other printed or lithographed paper and the like.

BACKGROUND It is common practice to mount photographic prints behind glass, perspex and other transparent media (such as the acrylic material sold in sheet form under the trade mark "Plexiglass"). When the mounted prints are to be used in commercial activities that include outdoor advertising, only prints mounted behind transparent media that are less _. brittle than glass are used, for glass is too susceptible to breakage (caused either accidentally or by vandals). Unfortunately, photographic prints mounted behind transparent non-glass materials deteriorate rapidly due to (a) the action of ultraviolet light on the emulsion of the print, and/or (b) the penetration of water vapour between the sheets of transparent material, and the subsequent action of the water vapour on the photographic emulsion. The problem of moisture affecting a print also exists with prints mounted behind glass sheets.

DISCLOSURE OF THE PRESENT INVENTION It is an object of the present invention to provide a method and apparatus for mounting a photographic print for display without the risk of deterioration of the photograph that exists when photographic prints are mounted in the conventional manner.

This objective is achieved by embedding the entire print within an acrylic material in such a manner that the emulsion of the print is bound to the acrylic material, which is itself bonded to a transparent acrylic "shield" (usually a thick sheet of acrylic material). The acrylic material used for the embedding step forms a gas-impermeable layer over the emulsion side and over the backing sheet of the print. The acrylic shield is conveniently a sheet of "Plexiglass" material which is sufficiently rigid to act as- a support for the print.

Thus, according to the broadest form of the present invention, a method of mounting a photographic print behind a substantially rigid, transparent acrylic sheet or shield comprises the steps of a) spreading a first layer of a mixture of an acrylic resin compound and a hardener on to the surface of said acrylic sheet; b) applying the emulsion side of the print to the first layer formed by this mixture and applying pressure to the print to cause the mixture to penetrate the pores of the emulsion; c) spreading a second layer of the mixture on the non-emulsion side (back) of the print in sufficient quantity that the first and second layers meet along the edges of the print, whereby the print is completely encapsulated by the first and second layers of the mixture; and d) allowing the first and second layers to harden.

The pressure required in step (b) is . only a small pressure.

In a preferred form of the invention, the print is rolled on to the sheet of acrylic material and the resin and hardener mixture is applied to the acrylic sheet immediately in front of the line of contact between the acrylic sheet and the emulsion of the print. This minimises the possibility of air bubbles being trapped between the emulsion and the resin material It also ensures that the emulsion of the print contacts the mixture before a skin forms on the mixture. It is also preferred that the second layer of the mixture is applied to the back of the print immediately behind the line of contact between the print and the acrylic sheet. If additional stiffness of the mounted photographic print is required, a further sheet of "Plexiglass" (or similar material), wood, aluminium or other metal, or a plastics material, may be clamped to, or bonded to, the back of the embedded print.

A photographic print mounted by the method of this invention is also encompassed by the present invention.

The present invention further encompasses apparatus for mounting a photographic print which includes a nozzle (preferably a reciprocating nozzle) which is mounted so that it can spread a mixture of acrylic resin and a hardener on to a transparent acrylic sheet. A roller in the apparatus bears against the back of the photographic print to gently press the emulsion side of the photographic print into the layer of resin and hardener mixture. The acrylic sheet is moved relative to the reciprocal path of the nozzle, and the photographic print is fed between the roller and the acrylic sheet, to ensure that there is a progressive contact between the emulsion of the print and the mixture of acrylic resin and hardener.

Thus, also according to the present invention, there is provided apparatus for the mounting of a photographic print on a substantially rigid, transparent acrylic sheet, said apparatus comprising a) means for supporting said acrylic sheet; b) a nozzle adapted to supply a mixture of an acrylic resin and a hardener through an outlet of the nozzle to one surface of the acrylic sheet over an area which is at least as wide as the width of the photographic print; c) a roller adapted to press the photographic print against the mixture applied to the acrylic sheet; and d) means to move the acrylic sheet relative to the nozzle and the roller while maintaining the distances between the outlet of the nozzle and the roller and said one surface of the acrylic sheet substantially constant.

The same nozzle and roller may be used to provide a second layer of resin and hardener to the back of the photographic print after the emulsion side of the print has been bound to the acrylic sheet. However, when used to apply a layer of acrylic- resin and hardener to the back of the photographic print, it will be necessary to interpose a film of a polyester or nylon material, or a film of another material which does not bond to acrylic resin, between the roller surface and the layer of acrylic resin and hardener, to prevent contact between the surface of the roller and the soft and tacky layer of acrylic resin.

In a preferred form of this apparatus, two nozzles and two rollers are included in the apparatus. The nozzles are adapted to supply the resin/hardener mixture to each side of the photographic print. One of the rollers is mounted to apply gentle pressure to the underside of the acrylic sheet while the other roller (protected by a film of polyester material or the like) is located so that it presses gently against the layer of resin and hardener on the back and around the edges of the photographic print.

In another aspect of the apparatus of the present invention, the acrylic sheet is mounted within a flexible envelope made from a material that is transparent to ultraviolet radiation. The acrylic sheet is longer than the print, and two elongate pods are. mounted on the region of the acrylic sheet on which it is intended that the print will not be mounted. Each pod is made from a flexible material that is opaque to ultraviolet radiation, and contains a one-component acrylic resin that is cured by the action of ultra-violet radiation. The elongate directions of the pods are substantially parallel to each other and to the width dimension of the acrylic sheet. Each .pod has an edge region that contains a line of weakness. A flap of the flexible envelope can be opened to permit a photographic print to be placed emulsion side down on the acrylic sheet, with one end of the print separating the edge regions of the two pods. After placing the photographic print on the acrylic sheet in this manner, the end of the envelope which is adjacent to the two pods is inserted between a pair of cylindrical rollers that have their cylindrical surfaces separated by a predetermined distance. The envelope is then passed through the rollers, the end of the envelope near which the pods are located being inserted between the rollers first. As the rollers compress the pods, each pod splits along its line of weakness. The rollers then act to spread the acrylic material from the pods over each side of, and over the edges of, the photographic print.

Usually, a tag or string is connected to the pods and extends through the end of the flexible envelope. After the passage of the envelope through the rollers, this tag is pulled to move the pods so that their edge regions are moved away from the photographic print and the encapsulation of the print within acrylic material is complete.

The acrylic material surrounding the print is then cured by placing the envelope and its contents in a region which is irradiated with radiation comprising ultraviolet light (for example, a region exposed to daylight) . The envelope can then be removed from the encapsulated print, which is bonded to the transparent sheet of acrylic material.

Thus, according to this further aspect of the present invention, there is provided apparatus for encapsulating a photographic print within acrylic material, said apparatus comprising: a) a flexible envelope made from a material which is transparent to ultra-violet radiation and which does not bond to an acrylic material, said envelope containing a sheet or shield of an acrylic material and having a flap therein which may be lifted to permit the photographic print to be placed on the acrylic sheet; b) a pair of generally elongate pods mounted within the envelope adjacent to and above one end of the acrylic sheet, each pod having a line of weakness parallel to the elongate direction of the pod; the elongate directions of the pods being substantially parallel to the width dimension of the acrylic sheet; each pod being made from a material which is opaque to ultraviolet radiation? each pod containing a quantity of a flowable, one-component, ultra-violet curing, acrylic resin; c) a pair of rollers mounted in a spaced apart relationship with their axes parallel to each other,- the spacing between the rollers being such that when the envelope is passed between them, the end of the envelope near which the pods are located being inserted between the rollers first, the rollers first cause the pods to be ruptured along their lines of weakness and then spread the acrylic material over and under the print that has been placed on the acrylic sheet. Preferably the pods are made from a metallic foil, or from a laminated flexible material containing a metal foil layer.

Embodiments of the present invention will now be described, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic sectional view of a photographic print mounted on a sheet of a transparent acrylic material by the method of the present invention.

Figure 2 illustrates the mounted print of Figure 1, given further support.

Figure 3 is a schematic sectional view showing the way in which a photographic print may be rolled on to a layer of acrylic resin material using one form of the apparatus of the present invention.

Figure 4 is a similar drawing to Figure 3, showing the use of an embodiment of the apparatus of the present invention which has two nozzles that supply an acrylic resin.

Figure 5 is a perspective sketch of an engineering prototype of the apparatus of the present invention. Figure 6 is a vertical sectional view, partly schematic, of the acrylic material application part of the prototype equipment shown in Figure 5.

Figure 7 is a sectional view though an embodiment of another aspect of the apparatus of the present inventio .

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Figure 1 shows a photographic print 10 positioned with its emulsion side embedded within a layer 11 of acrylic resin. The layer 11 of resin is bound to the emulsion of the print 10 and is bonded to the top surface of a sheet .12 of "Plexiglass" (or similar transparent acrylic material). Preferably, the print is a Cibachrome (trade mark) print, for, as noted by Remon Hagen in his paper entitled "Further improvements in the permanence of Cibachrome materials under adverse display conditions", published in the Journal of Imaging Technology, volume 12, pages 160 to 162, 1986, Cibachrome print ^" material is one of the most stable colour photographic print materials available, and the azo dyes incorporated into the silver dye bleach materials yield brilliant colour copies when the print is fixed.

To form the resin layer 11 of Figure 1, an acrylic resin material, such as "ACROFIX 90" (trade mark) marketed by Rohm GmbH of Darmstadt, Federal Republic of Germany, may be mixed with its hardener or catalyst "KATALYSATO 20" (also supplied by Rohm GmbH) at about 20 C for about five minutes. This mixture, containing about 3 per cent of the catalyst, is then centrifuged for five minutes to remove all air bubbles before being spread, as the layer 11, on to the top surface of the sheet 12.

The print 10 is then placed (preferably rolled) on to the resin layer 11, with the emulsion side of the print contacting the layer 11. As shown in Figure 3, it is preferred that gentle pressure is applied to the back of the print by a roller 20 at this stage to ensure that the resin mixture penetrates into the pores of the emulsion (and also into the micro-cavities of the polished surface of the material of the sheet 12). When the acrylic resin polymerises and becomes a solid polycrystalline material (a micro-crystallised acrylic resin), there is a true bonding between the layer 11 and the sheet 12, as the materials of the layer and sheet are essentially the same. However, because of the different nature of the acrylic material and the material of the emulsion of the print, there is not a true bond between the material of the layer 11 and the emulsion of the photographic print (this fact can be used to advantage if the print is subsequently to be removed from its mount, as explained in more detail below) . As shown in Figure 3, the resin mixture is preferably applied to the surface of the sheet 12 immediately in front of the line where the emulsion of the photographic print 10 would otherwise make contact with the upper surface of the sheet 12. This* technique minimises the possibility of air bubbles being trapped between the emulsion and the resin mixture.

To apply the acrylic resin mixture in this way, a dispenser 30 having a nozzle may be used. Since the width of the print that is being mounted exceeds the width of the outlet of the nozzle of the dispenser

30, it is necessary to oscillate the dispenser in a direction perpendicular to the plane of the paper when applying the resin mixture, to ensure that the layer 11 of acrylic material extends over the entire width of the print. The acrylic material from the dispenser is also placed on the sheet 12 in the region which will be alongside the edges of the print 10 when the print has been placed on the layer 11.

After the photographic print has been placed with its emulsion in contact with the layer 11 of acrylic material, an additional layer 13 of the acrylic resin and catalyst mixture is applied to the back of the print 10. The layer 13 covers the entire backing paper sheet of the print 10 and extends over its edges, to form, with the first layer 11 of acrylic material, a gas-impervious envelope around the print. Optionally, as shown in Figure 2, a second sheet 14 of "Plexiglass", or similar acrylic material, may be bonded to the layer 13 on the back of the print, thus forming a sandwich of two "Plexiglass" sheets containing a print between them. In one form of this sandwich, a second print may be mounted with its backing sheet adjacent to (and optionally bonded to) the backing sheet of the first print. With this arrangement, the second layer 13 of acrylic resin material may then be bound to the emulsion of the second print and also to the second "Plexiglass" sheet 14. Such a sandwich is particularly useful in advertising displays.

If additional support for the mounted photographic print is required, that additional support can be provided by a heavy backing sheet in place of the second "Plexiglass" sheet 14. The heavy backing sheet may be a sheet of wood, metal (for example, an aluminium alloy) or an opaque plastics material. If a translucent or semi-opaque plastics material is used as a backing sheet, fluorescent or other lighting may be used to back-light the mounted print.

A particular benefit of the use of an acrylic resin as the layers 11 and 13 each of which should be about 0.2 mm thick, but preferably not less than 0.2 mm thick) is that the acrylic resin is not only impermeable to gas, but it is a filter of almost all ultraviolet radiation and is optically more transparent than glass. Some prints mounted in accordance with the present invention have their colours enhanced by the mounting process.

Test strips of Cibachrome prints, mounted as shown in Figures 1 and 2, have been subjected to accelerated ageing using the "Atlas Weather-o-meter" equipment. This equipment bombards a mounted print with ultraviolet radiation in an atmosphere of eighty per cent relative humidity, at a temperature which is cycled between 28°C and 43°C. With this equipment, mounted Cibachrome prints have been subjected to 75,000 Langley (the equivalent of approximately three hundred years of ageing) with a maximum loss of density in magenta of 0.1 c.c. and a fraction less in the other colours. Unprotected test strips that were treated in the same manner in the same equipment were useless after 40,000 Langley. It is interesting to note that the achieved lifetime of the protected strips of Cibachrome prints is some ten times the manufacturer's quoted expected lifetime for Cibachrome emulsion.

When using the arrangement shown in Figure 3, it is preferable to mount the acrylic sheet 12 on a platform 31 that is moveable in the direction of the arrow A. A convenient platform is provided by the top surface of a small conveyor belt. Any suitable known mechanical or electro-mechanical mechanism may be used to provide the required movement of the platform 31. With this arrangement, the roller 20 can be a fixed roller and a dispenser having a nozzle 30 may be mounted for reciprocal movement in a direction substantially parallel to the plane of the upper surface of the acrylic sheet 12 (though preferably both the mounting of the roller 20 and the mounting of the dispenser 30 will be adjustable to permit the selection of a sheet 12 having any desired thickness as a shield or support for a print 10).

A modified form of the equipment illustrated in Figure 3 is depicted in Figure 4. In the Figure 4 embodiment, the nozzle 30 of the dispenser is mounted adjacent. to the nozzle 33 of a second dispenser and a guide 32 feeds a photographic print 10 between the nozzles 30 and 33 and into contact with the acrylic resin mixtures supplied through the nozzles 30 and 33 of the dispensers and on to the acrylic sheet 12. A fixed roller 36 and an adjustable roller 38 are used to apply gentle pressure to the multi-layer sandwich comprising the sheet 12, layer 11, print 10 and the layer 13.

When using the arrangement of Figure 4, it is necessary to provide a barrier between the roller 38 and the layer 13 of soft, uncured acrylic resin. Such a barrier is conveniently provided by a thin film 42 of a material (such as a polyester or nylon material) which does not bond with the layer 13 of acrylic resin. An end of the film 42 can be clamped between the sheet 12 and the platform 31 before the process of mounting the print begins. The film 42 may be supplied, as required, from a roll 43 of the film as the mounting of the print progresses.

With this system, it is preferable to leave the film 42 in contact with the resin layer 13 until the layers 11 and 13 have cured, to minimise the release of gases from the layers of acrylic mixture into the environment.

Preferably the two dispensers with their nozzles 30 and 33 are replaced by a single unit in which the acrylic resin and hardener are mixed in an airless mixing head and the mixture is supplied from the mixing head to a pair of nozzles 30 and 33. Such a mixing and supply arrangement is already available commercially.

Any required mixing ratio of the acrylic resin and hardener may be used. Additives may be included in the resin and hardener mix. One additive that has been used, successfully is the Ciba-Geigy agent "TINOVIN" (trade mark), which increases the absorption of ultraviolet radiation by the acrylic material.

Normally, after a print has been encapsulated between layers of acrylic material, the encapsulated print will be placed in a curing oven. In a preferred curing method, the temperature of the curing oven is raised to an initial temperature of about 60°C and is held at this temperature for about one hour. The oven temperature is then increased to about 70°C, which temperature is held for a further period of about one hour. The oven temperature is then increased to about 80 C and is maintained at about 80°C for about one hour, after which the oven is allowed to cool to ambient temperature. This curing process ensures that the applied layers of acrylic resin bond with each other at their edges, and the layer 11 bonds to the acrylic sheet, with all the acrylic materials having substantially the same molecular weight and the same physical properties. It will be appreciated, however, that other curing temperature sequences and times can produce satisfactory results.

By completely enclosing a photographic print within an envelope of acrylic material which does not actually bond to the emulsion or to the backing sheet, not only is the print protected but it can be removed from its mounting, if necessary. To remove a print from its surrounding acrylic material, the edges of the encapsulating material may be cut or trimmed so that the edges of the print are exposed when the material trimmed from the mounted print has been removed. The acrylic material bound to the print may then be separated from the print by prising the layers from the emulsion of the print and from its backing paper. The full-size engineering prototype equipment illustrated in Figures 5 and 6 was constructed to demonstrate that the apparatus of the present invention is suitable for industrial application, and to provide a basis from which production models of the apparatus can be designed and their components tested.

This prototype equipment is a realisation of the arrangement illustrated in Figure 4, and where - appropriate the same reference numeral will be used in Figures 4, 5 and 6 to denote the same or similar components.

The prototype equipment has two pairs of vacuum transport belts 31 upon one of which (or upon two of which, if the print 10 to be mounted is very wide) an acrylic sheet 12 is placed for transport to the region of the equipment where acrylic material and the print to be mounted are applied to the sheet 12. Before the sheet 12 is placed on a belt 31, a layer of Mylar (trade mark) or similar polyester film is placed underneath the acrylic sheet. The Mylar film is supplied from a dispenser 60 which is fed with Mylar sheet from a roll 61 mounted on a spider 62. The Mylar film is fed past the downstream side of a pair of nozzles 30 and 33 before the print to be mounted is inserted between the nozzles. After the Mylar film has been positioned under the acrylic sheet 12, the sheet 12 is moved by the transport belt until its leading edge 12A is beneath the output ends of the nozzles 30 and 33. Simultaneously, the print 10 to be mounted is fed, through print transport rollers 65, until it is between the nozzle outputs. At this point, a mixture of resin and hardener is supplied through the nozzles as the print is fed further towards the acrylic shield 12, which continues its movement through the machine in the direction of arrow B.

The nozzles 30 and 33 are moved reciprocally over the width of the print. To achieve this movement, each nozzle is mounted on a respective nozzle support carriage 66 which is moved to and fro along a respective cross bar 67. A respective cable attached to each nozzle support carriage connects the nozzle support carriage to a stepper motor. Activation of the stepper motor moves the cable first in one direction, then in the other direction. An alternative carriage movement arrangement, involving linear bearings on a shaft in place of the cable, is now preferred over the cable connection to each nozzle support carriage.

The feed rates of the print 10 through the print transport rollers 65 and the acrylic shield 10 through the equipment are matched. The movement of the nozzle support carriages 66 (and hence of the nozzles 30 and 33) is such that as the mixture of acrylic resin compound and hardener are pumped through each nozzle, a continuous layer of resin compound mixture is deposited below and above the print 10 as it is brought into contact with the acrylic shield 12.

The continued transport of the acrylic shield in the direction of arrow B takes it between a pair of precision ground polyurethane rollers 68. The spacing of the rollers 68 is set to be such that as the acrylic shield 12 with its print and layers of acrylic resin passes between the rollers 68, the pressure applied to the Mylar film 42 .(now below the acrylic shield or plate 12 and above the topmost layer of resin mixture) causes a uniform layer of acrylic resin, which is about, but preferably not less than, 0.2 mm thick, to coat each face of the print 10. If the resin coatings have a thickness which is less than about 0.2 mm, air bubbles tend to form in the coatings and incomplete polymerisation of the resin compound is experienced. If the coatings have a thickness which is significantly greater than about 0.2 mm, the cost of the mounting technique increases unnecessarily and the print may "float" within the resin coatings, so that in the final product, when the resin has cured, the print is not mounted in an optical plane.

At an appropriate point during the passage of the acrylic shield 12 and the print 10 through the rollers 68, the film of Mylar from the dispenser 60 is cut. In the prototype equipment, a cutter mounted on a linear bearing for movement across the width of the Mylar film is used for this purpose, but other cutting arrangements may be used.

After leaving the rollers 68, the assembly comprising the shield 12 with its plate 10 and the layers of acrylic resin compound, within the Mylar sandwich, is placed in an oven and the resin compound is cured as indicated above. Although the Mylar film may be removed from the assembly after the curing, the better practice is to leave the Mylar film in place to provide protection for the mounted print during transport and storage. In this way, when the mounted print is hung on a wall or placed within a display, and the Mylar film is then removed, the surfaces of the mounted print assembly are clean and unscratched.

Reverting, to the prototype equipment illustrated in Figures 5 and 6, it will be seen (from Figure 5) that the resin "Aerofix 90" and the catalyst "Katalysator 20" are pumped from their respective storage chambers 70 and 71 to be mixed in an airless mixing head 72 in the ratio 97:3. The acrylic resin mixture is supplied to the nozzles 30 and 33 by hoses 73 and 74, connected to the twin outputs of the mixing head 72. The entire operation of the prototype equipment shown in Figures 5 and 6 has been automated, the control of the operation being by a micro-computer, using a program written specifically for the purpose of operating the print encapsulation process.

Although reference has been made in the above description to the mounting of photographic prints, it will be recalled, from the introductory part of this specification, that this term includes photographic transparencies. Using the technique and apparatus of the present invention, it is possible to produce mounted transparencies which are readily back-lit, and thus are well-suited for advertising displays and exhibitions.

In the embodiment of the present invention which is illustrated in Figure 7, a flowable, single component, ultra-violet curable, acrylic resin material (such as the resin material marketed under the trade mark "ACROFIX 92" by Rohm GmbH) is stored in a pair of pods 51. The pods 51 are each elongate in the direction perpendicular to the plane of the paper of the drawing. The pods 51 have corresponding edge regions which contain lines of weakness 52, along which they rupture when the pressure within the pods is increased. The pods are made from a metallic film or foil, or other suitable material that is opaque to ultra-violet radiation. The pods 51 are mounted above but adjacent to one end of an acrylic sheet 48. The sheet 48 shown in Figure 7 is divided into a main portion and an end or subsidiary portion 48A by a notch 49 which extends across its underside. The presence of the notch 49 enables the subsidiary portion 48A of the sheet to be snapped off after a photographic print has been mounted on the main portion of the acrylic sheet.

The pods 51 and the acrylic sheet 48 are mounted within an envelope 53, which is made from a flexible and thin, ultra-violet transparent, polyester or similar material - for example, Mylar (trade mark) material - which does not bond to acrylic resins. A flap 58 forming part of one face of the envelope 53 is partially removable from the envelope to enable a photographic print 10 to be placed, emulsion side down, on the main part of the acrylic sheet 48. The end of the print 10 which is closest to the pods 51 is positioned between the edge regions of the pods 51 which contain the lines of weakness 52, so that one line of weakness is above the print 10 and the other line of weakness is below the print 10. The flap 58 is then replaced, to cover the print 10.

The flap 58 is preferably connected into the envelope 53 by a zip-fastener, by a strip of "Velcro" (trade mark) material, or by a strip of any other suitable material which enables the construction of an openable sealing arrangement. The flap need not be located at the end of the envelope which contains the pods 51, although that is the currently preferred position for the flap.

The envelope 53 is quite loose at the end which contains the pods 51. This loose end is inserted through the gap 55 between a pair of rollers 50 so that the entire envelope and its contents may be passed through the gap 55 by pulling it through the gap using the loose end of the envelope 53. When the envelope is pulled through the gap 55, the rollers 50 first compress the pods 51 until they split along the lines of weakness 52. The rollers then squeeze the flowable acrylic material from the pods 51 and spread it along each side of the print 10 and around the edges of the print. The gap 55 has a dimension such that when that portion of the envelope which contains the acrylic sheet 12 and the photographic print 10 is moved between the rollers, - each side of the print 10 receives a pre-metered coating of at least 0.2 mm of the flowable acrylic material (and preferably no more than about this thickness of acrylic material) .

After coating the print 10 with acrylic material, a string tag 54 which is connected to the pods 51 and extends through an aperture 59 in the end 58 of the envelope is pulled to move the pods 51 away from the end of the print 10, and thus enable the acrylic material from the pods to completely encapsulate the print 10. At this stage, the envelope 53 is placed in an environment into which ultra-violet light, or radiation containing ultra-violet light (for example, daylight) is admitted. The exposure of the acrylic material surrounding the print to this radiation will result in all of the applied acrylic material being cured. When the acrylic material surrounding the print 10 has been cured, the envelope 53 can be peeled off the print, and the subsidiary portion 48A of the acrylic sheet can be snapped off.

Those skilled in this art will recognise that although specific embodiments of the present invention have been described above, variations are possible without departing from the present inventive concept.

Claims

1. A method of mounting a photographic print (10) behind a transparent, substantially rigid, acrylic sheet (12) comprising the steps of a) spreading a first layer (11) of a mixture of an acrylic resin compound and a hardener on to the surface of said acrylic sheet; b) applying the emulsion side of the print to the first layer formed by this mixture and applying pressure to the print to cause the mixture to penetrate the pores of the emulsion; c) spreading a second layer (13) of the mixture on the non-emulsion side of the print in sufficient quantity that the first and second layers meet along the edges of the print, whereby the print is completely encapsulated by the first and second layers of the mixture; and d) allowing the first and second layers to harde .

2. A method as defined in claim 1, in which the print (10) is rolled on to said first layer (11).

3. A method as defined in claim 2, in which said mixture is applied to the surface of the acrylic sheet (12) to form said first layer immediately in front of the print (10) as the print is being rolled on to said first layer. 4. A method as defined in claim 1, claim 2 or claim 3, in which said application of pressure to the print is effected using a roller (20).

5. A method as defined in claim 3, in which the application of said mixture to form said second layer is effected immediately behind the contact point between the print and the first layer as the print is being rolled on to said first layer.

6. A method as defined in claim 5, in which said application of pressure to the print is effected using a pair of rollers (36, 38), one of said rollers (36) being mounted beneath said acrylic sheet and the other roller (38) being mounted above the second layer and being separated from said second layer by a film (42) of a material which does not bond to acrylic resin.

7. A method as defined in claim 6, in which said film is a film of a polyester material.

8. A method as defined in any preceding claim, including the step of subsequently bonding the second layer to a second substantially rigid sheet (14) of acrylic material or to a sheet of another rigid or substantially rigid material.

9. A method as defined in any preceding claim, in which an ultraviolet absorbing agent is included in the mixture of acrylic resin and hardener. 10. A method as defined in any preceding claim, in which said first and second layers have a thickness of about 0.2 mm.

11. A method as defined in any preceding claim, including the subsequent step of curing the applied acrylic resin and hardener mixture.

12. A method as defined in claim 11, in which the curing step comprises placing the mounted print in an oven and, in sequence, a) raising the temperature of the oven to about 60 C and maintaining that temperature for about one hour; b) raising the temperature of the oven to about 70 C ^• and maintaining the oven temperature at about 70 for one hour; c) raising the temperature of the oven to about 80 C and maintaining the oven temperature at about 80°C; and d) allowing the oven to cool to ambient temperature.

13. Apparatus for mounting a photographic print (10) on a substantially rigid acrylic sheet (12) comprising a) means (31) for supporting said acrylic sheet; b) a nozzle (30) adapted to supply a mixture of an acrylic resin and a hardener through an outlet of the nozzle to one surface of the acrylic sheet over an area which is at least as wide as the width of the photographic print; c) a roller (20) adapted to press the photographic print against the mixture applied to the acrylic sheet; and d) means to move the acrylic sheet relative to the nozzle and the roller while maintaining the distances between the outlet of the nozzle and the roller and said one surface of the acrylic sheet substantially constant.

14. Apparatus for mounting a photographic print (10) on a substantially rigid acrylic sheet (12) comprising a) means (31) for supporting said acrylic sheet so that said sheet is generally horizontal; b) a first nozzle (30) adapted to supply a mixture of an acrylic resin and a hardener through an outlet of the nozzle to the upper surface of the acrylic sheet over an area which is at least as wide as the width of the photographic print; c) a second nozzle (.33 ) mounted adjacent to but spaced apart from the first nozzle (30), said second nozzle being adapted to supply a mixture of an acrylic resin and a hardener through an outlet thereof to the back of said photographic print; - 30 -

d) first and second cylindrical rollers (38 and 36) mounted with their axes parallel and spaced apart so that, when the assembly of the acrylic sheet with said print and said first and second layers of mixture is passed between said rollers, pressure is applied by said rollers to said assembly; e) guide means (32) to guide said print between the first and second nozzles towards the acrylic sheet; and

.f) means (43) for supplying a film (42) of a material which does not bond to acrylic resin and for positioning said film between the first roller (38) and the mixture supplied by said second nozzle.

15. Apparatus as defined in claim 13 or claim 14, in which said means for supporting the acrylic sheet is a platform having a planar upper surface, the platform being mounted for movement in the plane of its upper surface.

16. Apparatus as defined in claim 15, in which said platform is the upper surface of a conveyor belt.

17. Apparatus as defined in any one of claims 13 to 16, in which said or each nozzle is reciprocally moveable in a direction which is orthogonal to the direction of movement of the acrylic sheet relative to the outlet of the or each nozzle. 18. Apparatus for mounting a photographic print (10) on a substantially rigid acrylic sheet (12) comprising: a) at least one transport belt (31) mounted for substantially horizontal travel through said apparatus; b) a pair of nozzles (31, 33) mounted a predetermined distance above said at least one transport belt; c) reciprocal movement means for moving said nozzles reciprocally in a direction orthogonal to the direction of said travel while maintaining said predetermined distance; d) print transport rollers (65) mounted between said nozzles for feeding said print between said nozzles towards said at least one transport belt; e) a mixer having a mixing head .(72) with two outlets, said mixing head outlets being connected by respective hoses (73, 74) to said nozzles (30, 33), said mixer receiving acrylic resin and hardener from respective supplies ' hereof; f) a dispenser of polyster film mounted above said at least one transport belt; and g) a pair of cylindrical rollers (68) mounted within said apparatus downstream in the direction of travel with respect to said nozzles, said rollers having their axes parallel to each other and to the direction of reciprocal movement of said nozzles, said rollers being spaced apart a predetermined distance which is substantially equal to the thickness of said acrylic sheet plus the thickness of said print plus twice the thickness of the polyester film plus 0.4 mm.

19. Apparatus as defined in claim 18, in which each said nozzle is mounted on a respective nozzle support carriage (66) and said reciprocal movement means comprises a pair of cables attached to, respectively, the nozzle support carriages and a stepper motor for moving said cables.

20. Apparatus as defined in claim 18, in which each said nozzle is mounted on a respective -nozzle support carriage (66) and said reciprocal movement means comprises a pair of shafts connected to, respectively, the nozzle support carriages by linear bearings, and a stepper motor for rotating said shafts.

21. Apparatus as defined in any one of claims 18, 19 and 20, including means for cutting said polyester film.

22. Apparatus as defined in any one of claims 18 to 21, including a computer activated control system and a microcomputer programmed to control the operation of the apparatus to cause the apparatus to mount said print on said acrylic sheet. 23. Apparatus for mounting a photographic print (10) on a substantially rigid, transparent, acrylic sheet (48), said apparatus comprising: a) a flexible envelope (53) made from a material which is transparent to ultraviolet radiation and which does not bond to an acrylic material; said envelope having an upper wall and a lower wall and containing the acrylic sheet (48), said upper wall having a flap (58) therein which may be lifted to permit the photographic print to be placed on.the acrylic sheet; b) a pair of generally elongate pods (51) mounted within the envelope adjacent to and above one end of the acrylic sheet, each pod having a line of weakness (52) parallel to the elongate direction of the pod; the elongate directions of the pods being substantially parallel to the width dimension of the acrylic sheet; each pod being made from a material which is opaque to ultraviolet light; each pod containing a quantity of a flowable, one-component, ultra-violet curable, acrylic resin; c) a pair of rollers (50) mounted in a spaced apart relationship with their axes parallel to each other, the spacing between the rollers being such that when the envelope is passed between them, the end of the envelope near which the pods are located being inserted between the rollers first, the rollers first cause the pods to be ruptured along their lines of weakness and then spread the acrylic material or mixture over and under the print that has been placed on the acrylic sheet.

24. Apparatus as defined in claim 23, in which a tag

(54) is connected to said pods and extends through an aperture (59) in the end (58) of said envelope which is closest to said pods.

25. Apparatus as defined in claim 23 or claim 24, in which said pods are made of a metallic film or foil.

26. Apparatus as defined in any one of claims 23 to

25, in which the spacing (55) of said rollers is adjustable and is set to a value which is about, but is at least, the sum of the thickness of the acrylic sheet plus twice the thickness of the envelope material plus 0.4mm.

27. Apparatus as defined in any one of claims 23 to

26, in which said acrylic sheet has a main portion and a subsidiary portion (48A), the boundary between said main and subsidiary portions being defined by a notch (49) in the acrylic sheet, said pods being mounted above said subsidiary portion and said print being placed above said main portion, said acrylic sheet being fracturable along the line of said notch. 28. Apparatus as defined in any one of claims 23 to 27, in which the envelope is made from a polyester material.

29. A method of mounting a photographic print, substantially as hereinbefore described with reference to the accompanying drawings.

30. Apparatus for mounting a photographic print substantially as hereinbefore described with reference to Figure 3, or Figure 4, or Figures 5 and 6, or Figure 7 of the accompanying drawings.