GB2335695A

GB2335695A - Colour fade protection systems

Info

Publication number: GB2335695A
Application number: GB9906839A
Authority: GB
Inventors: Michael Glover
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-26
Filing date: 1999-03-24
Publication date: 1999-09-29
Also published as: GB9906839D0; CA2233387A1

Abstract

A multi-layered sealed unit 20 incorporating one or more coloured features 21 that can fade in the presence of visible light, comprises two or more sheets 22, 23 that are essentially impermeable to oxygen. A front one of the sheets 22 is transparent, generally rigid in form and incorporates a UV-filter, and the sheets are maintained in an essentially parallel and spaced apart relationship to each other by a peripheral spacing-and-sealing assembly 34,37 enclosing a sealed chamber within which the coloured features are located. The unit includes oxygen-absorbing material positioned to be exposed to said chambers. The coloured feature may be a separate display object including oil paintings, water colour paintings, pencil drawings, engravings, photographs and printed images. The front sheet is of glass and the oxygen-absorbing material is provided in sheet form. The rear sheet may consist of flexible, multi-layer barrier film material.

Description

1 1 i ? _ -2 1 COLOUR FADE PROTECTION SYSTEMS 2335695 This invention

relates generally to color fade protection systems and specifically to sealed units incorporating decorative features that can color fade in the presence of visible light.

Museum professionals have long recognised the problem of color f ading and experience has shown that even where UV light filters are used, certain fugitive colors can fade due to exposure to visible light. To help prevent color fading of these fugitive colors, it has been proposed by Stefan Michalski that display objects should be located in oxygen-free, micro environments (Papers of the Conference, "Lighting in Museums, Galleries and Historic Houses", Museum Association, London, 1987). However in his paper, Michalski points out that although the task is not impossible, there are no practical and cost effective methods available for fabricating these oxygenfree micro-environments.

An early UK Patent 6556 issued to Simpson describes a sealed enclosure for display objects that features a glass sheet sealed to a metal casing using putty cement. A vacuum is created within the sealed enclosure by extracting air using a nozzle arrangement. Although with Simpson's invention, an oxygen-free environment would be realised if a vacuum could be achieved, the proposed assembly method is not practical because even if vacuum conditions could be achieved, the outer glass sheet would implode and break under atmospheric pressure.

US Patent 4,646,914 issued to Gipson, describes a sealed enclosure for display objects that features a transparent plastic front covering, a plastic foam backing board and a perimeter-edge sealing tape. Although the sealed enclosure is filled with inert gas, the enclosure walls are gas permeable and as a result, there would be a gradual oxygen build-up.

1 2 US Patent 5,238,648 issued to Kremen describes a sealed enclosure that incorporates input and output valves that allow for the inert gas to be recharged as required. Although effective in maintaining an oxygen-free environment, these valve port enclosures are complex and expensive to manufacture.

US Patents 5,219,524 and 5,260,023 issued to Evans, describe a sealed enclosure fabricated from flexible plastic sheets that are heat sealed at the perimeter edge. To provide stable conditions and help prevent mold and insect infestation, the document enclosure system incorporates both moisture and oxygen- absorbing material. For various technical reasons, this document enclosure system has not proved effective and the product has not been successively commercialized.

For the oxygen scavenger system, Evans proposed the use of Ageless Z which is a product manufactured by Mitsubishi Gas Chemical Company and consists of iron powder mixed with a natural zeolite which is impregnated with a saturated solution of sodium chloride. The material is packaged in sachets and is promoted as a non-toxic, residue-free method of preserving food stuffs against mould, aerobic bacterial growth and insect attack.

For museum conservation applications, the Ageless Z oxygen scavenger has also been used to obtain low oxygen atmospheres for the treatment of insect-infested museum objects and for preserving archival materials against mould. It has also been used for the display and storage of airsensitive materials such as rubber.

In a technical paper by David Gratten and Mark Gilberg, (see Ageless Oxygen Absorber: Chemical and Physical Properties, Studies in Conservation 39, 1994), the authors reviewed the use of Ageless Z for museum applications. They concluded that given the exothermic nature of the reaction of oxygen with iron, Ageless Z sachets should not be allowed to come into physical contact with an object. Furthermore using the Ageless Z product, objects vulnerable to damage should not be stored under low-oxygen atmospheres unless the relative humidity can be controlled in some way.

e- -\ t 1 - ', 3 For sealed glazing units, various efforts have been made to incorporate decorative features within their controlled, moisture-free environments. Canadian patent 793,040 describes the application of a decorative pattern onto a glass surface using an enamel frit. Because the enamel frit is fused to the glass sheets at high temperatures, the decorative pattern is very durable and does not color fade even after extended exposure to sunlight. However, this enamel frit production technique is slow and complex and requires expensive equipment.

As described in US patent 5,449,426, issued to Lin, an alternative approach to preventing color fading is to incorporate the decorative feature within a laminated glass assembly. Partly because the polyvinylbutryl (PVB) sandwich layer acts as a UV-filter, this laminated glass technique is effective in preventing color fading. However, this technique is also slow and complex and requires expensive equipment. In addition, this technique is not suitable for sealed units incorporating multiple layer decorative patterns such as those described in US patent 5,494,715 issued to Glover.

Particularly for custom decorative images such as stained glass designs, there are cost and productivity advantages if the decorative designs can be applied to a flexible film which is laminated to a rigid glass sheet. decorative design is applied using an electronic ink jet printer. However, because these ink-jet printers use waterbased inks, the printed images tend to quickly fade on exposure to light and this technique is not suitable for applications requiring long term durability.

The invention provides a multiple layer sealed unit incorporating one or more decorative features formed of a material that can fade in the presence of visible light, comprising: two or more sheets that are essentially impermeable to oxygen, a front one of which is transparent, generally rigid in form and incorporating a Uv-filter, said sheets being 4 maintained in an essentially parallel and spaced apart relationship to each other by a peripheral spacing-and-sealing assembly, and defining between them one or more sealed chambers within which said decorative features are located, wherein said unit includes oxygen-absorbing material positioned to be exposed to said chambers.

A decorative feature incorporated within the sealed unit may comprise a separate display object, e.g. oil painting, water-color painting, pencil drawing, engraving, photograph, or printed image. Preferably, the front sheet is made from glass while a rear sheet may be opaque or transparent. The front sheet is preferably spaced apart from the rear sheet by at least 2 mm and where the spacing between the front sheet and rear sheets is more than 6 mm, the chamber may be filled with an inert gas such as argon.

For sealed units incorporating art work, it is recommended that an antireflective coating is applied to on one or both surfaces of the front sheet and one preferred option is for the anti-reflective coating to be applied to a flexible plastic film incorporating UV-absorbers that is laminated to one or both sides of the front sheet. The oxygenabsorbing material is typically provided in flexible sheet form and this flexible sheet can be laminated to a rear sheet of multi-layer barrier film material.

The peripheral spacing-and-sealing assembly also typically consists of a structural seal and a gas-barrier seal with preferably the structural seal being positioned inwardly of the gas barrier seal. Preferably, the gas barrier seal consists of a tape with preapplied polyisobutylene or butyl material which is wrapped continuously around the perimeter edge of the sealed unit.

For paper art work units, the structural seal preferably consists in part of a barrier film tape with preapplied pressure sensitive adhesive and this barrier film tape structurally connects the flexible barrier film back sheet, a back mat board, a front mat board and the front glass sheet. The structural seal may also consist in part of a flexible desiccant -filled foam spacer with pre-applied pressure sensitive side adhesive.

For conventional sealed glazing units typically used for building applications, the colored decorative features may be incorporated in different ways. For example, the decorative feature can be applied directly to one or more of the glazing sheets using inks or paints. Alternatively the decorative feature can be first applied using an ink jet printer to a flexible plastic film material that is laminated to one of the glazing sheets. A further option is for the decorative feature to be created from flexible strips of film material that are applied to one or more of the glazing sheets.

For conventional sealed units, the oxygen-absorbing material can be provided in sheet form but also can be incorporated within the spacingand-sealing assembly in various ways and using different material compositions. For sheet material, oxidizable organic compounds with transition metal catalysts is one preferred material composition for the oxygen absorbing material.

The following is a description by way of example of certain embodiments of the present invention, reference being made to the accompanying drawings, in which:

Figure 1 shows an exploded perspective view of a sealed unit incorporating a colored paper artwork.

Figures 2A and 2B show alternative perimeter edge cross section details of a sealed unit incorporating a colored paper artwork.

Figures 3A to 3D show a four-step process for assembling the structural seal for a sealed unit incorporating a colored paper art work. Figure 4 shows a cross section detail of a wood picture frame with a sealed unit incorporating a colored paper art work.

Figure 5 shows a cross section perimeter-edge detail for a sealed unit incorporating an oil painting.

k 1 - '; is 6 Figure 6 shows a cross section perimeter-edge detail of double-glazed sealed unit incorporating a decorative feature applied directly to the glass.

Figure 7 shows a cross section perimeter-edge detail of a double-glazed sealed unit incorporating a laminated plastic film with a printed decorative feature.

Figure 8 shows a cross section perimeter-edge detail of a triple-glazed sealed unit incorporating decorative patterns made from strips of plastic film material.

Figures 9A to 9C show alternative cross section, perimeter-edge details of a double-glazed unit incorporating oxygen-absorbing material within the spacer-and-sealing assembly.

Figure 1 shows an exploded perspective view of a sealed unit 20 that incorporates a colored paper artwork 21 incorporating colors and pigments that can fade in the presence of visible light. The specific art work illustrated in Figure 1 is a water color painting and this type of painting is particularly subject to color fading problems.

The sealed unit 20 is manufactured from a glass front sheet 22 and a multi-layer, plastic film back sheet 23. A plastic film sheet 24 is laminated to either or both sides of the front glass sheet 22. The plastic film includes Uvabsorbing material which is either incorporated within the film material and/or the adhesive used to adhere the plastic film 24 to the front glass sheet 22. The coated film sheets 24 are typically adhered to the glass with an optically clear, wateractivated adhesive. In addition to providing W-protection, the laminated plastic film sheet 24 also helps prevent damage to the artwork due to accidental glass breakage or vandalism.

To help improve visible light transmission, the plastic film can also incorporate an anti-reflective coating. The addition of these antireflective coatings help ensure that the artwork colors are not dulled and also reduces distracting reflections from light bulbs and other high intensity light -..I 7 sources. one manufacturer who produces a suitable antireflective plastic film product is Courtaulds Performance Films of Martinsville, Virginia. An alternative to using a plastic film with a preapplied anti-reflective coating is to apply the anti-reflective coating directly to the glass and a suitable two-sided coated glass product is manufactured by Denton Vacuum Inc. of Moorestown, New Jersey. There is still a need for a UV- filter and this can be achieved by using laminated glass where the 10 polyvinylbutryl (PVB) adhesive material between the two glass sheets incorporates UV-absorbers. The multi-layer laminated plastic film back sheet 23 consists of a sheet of oxygen absorbing material 25 that is laminated to a moisture/gas barrier sheet material 26. One 15 preferred product for the oxygen absorbing material is produced by Cryovac, North America who are located in Duncan, South Carolina. The product is described in US patent 5,425,896 issued to Speer et al and the material composition consists of oxidizable organic compounds and transition metal catalysts. 20 The required thickness of the oxygen absorbing sheet 25 varies depending on the width of the picture cavity. Sufficient oxygen absorbing material must be included to absorb both the initial oxygen content in the picture frame cavity as well as additional oxygen absorbing material to soak up any oxygen that diffuses through the edge- seal and backing sheet over an extended multi-year period. The moisture/gas barrier film sheet 26 is a multilayer structure incorporating a metallized plastic film and one preferred product is Marvelseal which is produced by the Ludlow 30 Corporation of Homer, Louisiana. A conventional mat board structure is used to display the paper artwork 21. The structure consists of a front mat board 27 with an opening 28 and a back mat board 29. Both mat boards 27 and 29 are made from cardboard and it is recommended that acid-free archival 35 material is used. The artwork 21 is typically adhered to the back mat board 29 using strips of pressure sensitive paper adhesive tape 8 at the two top corners 31. The pressure sensitive tape is specifically designed for use in libraries and archives and one suitable tape product, which is described in US patent 4,725,498, is manufactured by Hans Neschen GmEH of Buckeburg, Germany.

Figure 2A shows a cross section, perimeter-edge detail of a sealed unit 20 incorporating a colored paper artwork 21. The front and back mat boards 27 and 29 are adhered together at the perimeter-edge using a multi-layer barrier film tape 32 with pre-applied pressure sensitive adhesive 33. As well as structurally holding the two mat boards 27 and 29 together, the barrier tape 32 prevents any sticky butyl material from the perimeter edge from contacting the mat boards.

is The multi-layer barrier back sheet 23 is adhered to the back mat board 29 using pressure sensitive adhesive 33.

The pressure sensitive adhesive 33 must be non-outgassing and one preferred material is an acrylic pressure sensitive adhesive. The combined sub-assembly of front and back mat boards 27 and 29 is adhered to the front glass sheet 22 using an adhesive foam tape 34. The adhesive tape features pre applied acrylic pressure sensitive adhesive 33 on either side of the foam tape 34. The foam material is non-outgassing and because of its low volatile content, silicone foam is the preferred material. One suitable silicone foam tape product is manufactured by Edgetech IG Inc of Cambridge, Ohio.

Because the film 24B is adhered to the front glass sheet 22 using a clear distortion-free adhesive which is typically water activated, the plastic film can incorporate high levels of moisture that can evaporate and possibly cause excessive relative humidity levels within the sealed unit. To soak up this moisture, the foam tape 34 incorporates desiccant material and the preferred desiccant material is 3A molecular sieve as this ensures that relative humidity levels within the sealed unit stay comparatively stable under fluctuating temperature and pressure conditions.

It should be noted, however, that relative humidity 1 j 9 levels within the sealed unit are generally controlled through moisture storage within the cardboard mat boards 27 and 29. For this reason, it is important that prior to the encapsulation of the artwork, the mat boards are stored for some time at the recommended relative humidity levels for the artwork. In addition, the encapsulation of the artwork should also be carried out in an interior environment maintained at the recommended relative humidity levels for the artwork.

The foam tape spacer 34 is typically first applied to the perimeter-edge of the glass sheet 22. The front glass sheet 22 is then matched with the mat board assembly 36. The pressure sensitive adhesive on the spacer sides is then wet-out using simple hand pressure. A perimeter-edge sealing tape 37 is then applied around the perimeter edge 38 of the unit 20.

The sealing tape 37 consists of an outer barrier film 52 and an inner layer of polyisobutylene and/or butyl composite materials 51. The advantage of using polyisobutylene material is that the sealant can be adequately wet-out at room temperatures and there is no need for a heating process that could potentially damage a fragile artwork.

The sealing tape 37 is applied continuously around the perimeter edge 38 of the sealed unit 20 and at the start and end points the tape is overlapped. At the corners, the two inner sticky butyl sides of the tape 37 are pinched together and the tape is then folded down on both outward facing surfaces 39A and 39B of the sealed unit 20.

To ensure an adequate gas barrier seal, the sealing tape 37 should overlap the outward facing surfaces 39A and 39B by at least 4 mm. To wet- out the polyisobutylene sealant material 51, simple hand pressure can be applied and a simple roller hand tool can also be used to ensure full surface contact between the polyisobutylene sealant material 51 and the glass sheet 22 and barrier film 26. It should be noted that at the perimeter edge 38, the anti- reflective film 24A is cut back so that the polyisobutylene material is in full surface contact with the glass sheet 22.

After the perimeter edge 38 has been sealed, the oxygen-absorbing sheet material 25 removes the oxygen from the flat chamber 43 between the front glass sheet 22 and the multilayer backing sheet 23. As a result of incorporating a uvfilter and also essentially eliminating oxygen from within the chamber space, color fading of the paper artwork 21 is substantially reduced.

Compare to using separate sachets, there are three main advantages of incorporating the oxygen-absorbing material within sheet material. First, the oxygen-absorbing material can be placed in close contact with the artwork. Second, the width of the chamber space can be minimized. Third, the production process tor manufacturing the sealed unit is significantly simplified.

Because most damage to museum objects occurs while they are being transported from one location to another, the need for an easy process for micro encapsulation of display objects is critical. By using a dual-seal combination of a structural, barrier film pressure sensitive adhesive tape and a polyisobutylene sealing tape, the process of perimeter sealing is significantly simplified and can be carried out without the need for any elaborate equipment.

Figure 2B shows an alternative perimeter edge detail of a sealed unit 20 incorporating a colored paper artwork. The front and back mat boards 27 and 29 are adhered together at the perimeter edge using a barrier film 32 with pressure sensitive adhesive 33 pre-applied on both sides of the tape. Both the front glass sheet 22 and the multi-layer back sheet 23 are adhered to the front and back mats 27 and 29 using pressure sensitive adhesive 33. No desiccant foam is incorporated within the edge seal and any excess moisture from the wateractivated adhesive that is used to bond the plastic film 24B to the glass sheet 22 is absorbed by the cardboard mat boards 27 and 29.

Figures 3A to 3D show a four step process for assembling the structural seal 40 for a sealed unit incorporating a colored paper art work. The structural seal 40 consists of a barrier film tape 32 with double-sided pressure 11 sensitive adhesive and four separate release liners 41, 42, 43 and 44.

In Figure 3A, the multi-layer barrier sheet film 26 with pre-applied oxygen-absorbing sheet material 25 is laid flat on a work surface 45. The first release liner (not shown) is removed from the barrier film tape 32 and the tape is applied to the perimeter edge of the barrier sheet film 26.

In Figure 3B, the second release liner 42 is removed from the barrier film and the back mat board 29 is placed on top of the back sheet. The paper art work 21 is positioned on the back mat board 29 and is held in position at the corners using two strips of paper tape 30.

In Figure 3C, the front mat board 27 with an opening 28 is placed in position on the back mat board 29. The third release liner 43 is removed and the barrier tape is folded over and adhered to the top surface 46 of the front mat board 27.

In Figure 3D, the fourth release liner 44 is removed and the front glass sheet 22 is adhered to the front mat 27. All four layers of the pressure sensitive adhesive 33 are wet- out using simple hand pressure. With the artwork safely protected within the glass/mat board sub-assembly, the gas barrier film 52 with the sticky polyisobutylene material 51 can then be wrapped around the perimeter edge of the sealed unit 20 without concern that the art work may be accidently damaged.

Figure 4 shows a cross section detail of a wood picture frame 54 with a sealed unit 20 that incorporates a colored paper artwork 21. The sealed unit 20 is conventionally installed within the picture frame 54. To protect the multi layer barrier film sheet 22 from accidental damage, a backing sheet 55 is located on the back face of the picture frame 54. The backing sheet 55. can be made from various materials including: hardboard, cardboard and rigid plastic foam. Using special pins 56, the backing sheet 55 is held in position against the sealed unit 20. Through applying a small compressive force at the perimeter edge 38, the sealing tape 37 remains in firm contact with the front glass sheet 22 and the multi-layer back sheet 23 and this helps to maintain the 7 "-.11 12 integrity of the barrier seal.

Figure 5 shows a cross section detail of a wood picture frame 54 with a sealed unit 20 that incorporates a canvas oil painting 58. The sealed unit 20 consists of a front glass sheet 22 with pre-applied plastic films 24A and 24B laminated to both sides. The plastic films feature an antireflective coating and incorporate UV absorbers. The back sheet 59 is made from a thin metal sheet of aluminum or stainless steel. A sheet of oxygen absorbing material 25 is taped to the metal sheet 59.

The perimeter edge seal 60 consists of a metal Ushaped channel 61 with double-sided adhesive foam tapes 34 applied to the top 62 and bottom 63 legs of the U-channel 61. The double-sided adhesive foam tapes 34 structurally adhere the metal channel to the front glass sheet 22 and back metal sheet 59. A sealing tape 37 is adhered to outward facing surfaces 48 and 49 of the glass sheet 20 and the metal backing sheet 59.

The sealed chamber 66 is filled with inert gas using conventional gas filling techniques used in the insulating glass industry. However, it should be noted that because of the physical obstruction provided by the oil painting 58, it is difficult to achieve high gas fill levels and the oxygen absorbing sheet material 25 is required to remove any oxygen that may remain in the sealed chamber.

The oil painting 58 is fixed in position within the sealed cavity 66 by means of wood screws 65 that attach the metal channel 61 to the wood stretcher 64. A spacer 67 separates the metal channel 61 from the bottom edge of the canvas painting 58. The spacer 67 can be made from traditional cork fittings or alternatively a low density, open-cell silicone foam material. The foam tapes and spacers help protect the oil painting from impact damage and also can help reduce canvas vibration particularly when the painting is being transported by moving vehicles. The sealed unit 20 is installed within the frame 54 and is held in place by means of a wood batten 67.

Figures 1 to 5 show examples of a water color ( 'I 13 painting and an oil painting being incorporated in a sealed unit containing oxygen absorbing material in sheet form. It can be appreciated by those skilled in the art that other types of display objects can be incorporated in a sealed unit containing oxygen absorbing material and these display objects can include: pencil and pastel drawings, historic documents, engravings, photographs, printed images and outdoor advertising materials.

Figure 6 shows a cross section detail of the perimeter edge seal 60 of a sealed glazing unit 76. The perimeter edge seal 60 separates a front glass sheet 22 and a back glass sheet 68. Although glass is the preferred material, plastic glazing sheet material such as polycarbonate or acrylic can also be used. When the sealed unit 76 is installed within a building, the front glass sheet 22 is located adjacent to the exterior and the back glass sheet 68 is located adjacent to the building interior. A flexible plastic sheet of oxygen absorbing material 25 is adhered to the cavity face of the front glass sheet 22. The plastic sheet 25 incorporates UVabsorbers or alternatively the adhesive used to adhere the plastic sheet 25 to the glass sheet 22 can incorporate UVabsorbers. A colored decorative feature 71 is applied directly to the cavity face of the back glazing sheet 66. The colored decorative feature 71 is produced using inks or paints and when exposed to UV and visible light, these colored inks and paints can gradually fade over time.

The two glass sheets are sealed at the perimeter edge using conventional insulating glass technologies. one preferred technology is to use a desiccant-filled foam spacer 72 that is manufactured by Edgetech IG Inc of Cambridge, Ohio. The foam spacer is marketed under the registered trade name of Super Spacer@ and features pressure sensitive side adhesive. Typically, the foam spacer 72 is backed up by hot melt butyl sealant 73. The glazing chamber 74 between the two glass sheets 22 and 68 is filled with an inert gas such as argon. However it should be noted that when using conventional gas filling techniques, it is difficult to achieve higher fill 1 1 \- 1/ ' 14 levels than 95 per cent. Consequently, the oxygen absorbing material is required to both absorb any oxygen that remains in the unit and also absorb any oxygen that enters the unit through the perimeter edge seal 60 over an extended period of 5 time.

Figure 7 shows a cross section detail of the perimeter edge seal 60 of a sealed glazing unit 76 incorporating a laminated plastic film 25 with a printed decorative feature 71. The dual seal, perimeter-edge detail is the same as illustrated in Figure 6. The laminated plastic film incorporating oxygen- absorbing sheet material 25 is also the same as illustrated in Figure 6 and the plastic sheet film material and/or adhesive also incorporates UV-absorbers. In addition, the chamber surface face 77 of the flexible film is specially treated to be print receptive and a decorative feature 71 is applied to cavity surface face using an electronic printing system such as an ink-jet printer.

A wide variety of decorative printed images can be applied including simulated stained glass designs and advertising material. Typically ink jet images fade on exposure to UV and visible light but by using the combination of UV absorbers and an oxygen- free environment, color fade problems are substantially reduced.

Figure 8 shows a cross section perimeter edge detail of a triple-glazed sealed unit 75 incorporating decorative patterns made from strips of plastic sheet material 77. In order to simulate the appearance of traditional muntin grid windows, the plastic strips 77 are applied in registering patterns as described in US patent 5,494,715. Slimline white PVC muntin grids 78 can be positioned on either side of the registering patterns and this further helps create the visual appearance of a traditional muntin grid windows. The strip sheet material 77 incorporatesboth UV absorbers and oxygenabsorbing material. By providing the combination of Uv- absorbers and an oxygen-free environment, the problem of color fading is substantially reduced and this allows the muntin strips to be strongly colored creating a distinctive visual is image.

Figure 9A, 9B and 9C show cross sections of various alternative perimeteredge details of a double glazed sealed units 76 with a UV-absorbing plastic film 31 laminated to the cavity face 69 of the front glass sheet 22 and with a decorative feature 71 applied to the film 31 typically using an electronic printer. The cavity face of the flexible film is specially treated to be print receptive. The flexible plastic film as well as being UV-absorbing also provides other performance advantages such as increased protection against vandalism and storm damage. Special solar control and low-e coatings can also be incorporated as part of the flexible film.

In Figure 9A, the spacing-and-sealing assembly 80 consists of a hollow metal spacer 79 with polyisobutylene 51 on the sides and with the spacer 79 backed by conventional insulating glass sealant 73. Both oxygenabsorbing material 86 and moisture-absorbing desiccant material 87 is incorporated in bead form within the hollow metal spacer 79.

In Figure 9B, the spacing-and-sealing assembly 80 consists of a desiccant-filled foam U-channel spacer 82 with pre-applied pressure sensitive side adhesive 33 and a vapourbarrier backing 72. The U- channel is filled with a matrix material 83 containing oxygen-absorbing material 86 and the spacer is backed by conventional insulating glass sealant material 73.

In Figure 9C, the spacing-and-sealing assembly 80 consists of a foam spacer 72 with preapplied pressure sensitive side adhesive 33 and a vapour barrier backing 82. The spacer 72 incorporates both oxygen- absorbing material and moisture-absorbing, desiccant-fill material. The foam spacer 72 is backed by conventional insulating glass sealant material 73.

11 1 p 16

Claims

CLAIMS:

1. A multi-layer sealed unit incorporating one or more decorative features that can fade in the presence of visible light, comprising: two or more sheets that are essentially impermeable to oxygen, a front one of which is transparent, generally rigid in form and incorporates a UV-filter, said sheets being maintained in an essentially parallel and spaced apart relationship to each other by a peripheral spacing-andsealing assembly, and defining between them at least one sealed chamber within which one or more of said decorative features are located, wherein said unit includes oxygen-absorbing material positioned to be exposed to said chambers.

2. The sealed unit of claim 1 wherein said colored feature is a separate display object including oil paintings, water color paintings, pencil drawings, engravings, photographs and printed images.

3. The sealed unit of claim 1 or claim 2 wherein said front sheet is of glass.

4. The sealed unit of any one of claims 1 to 3 wherein said oxygenabsorbing material is provided in sheet form.

5. The sealed unit of any one of claims 1 to 4 incorporating a rear sheet consisting of flexible, multi-layer barrier film material.

17

6. The sealed unit of claim 5 wherein said oxygenabsorbing material is laminated to said rear sheet.

7. The sealed unit of claim 1 where said UV filter is a plastic film laminated to said front sheet.

8. The sealed unit of any one of claims 1 to 7 wherein said transparent front sheet incorporates an anti-reflective coating on at least one surface thereof.

9. The sealed unit of claim 8 wherein said anti reflective coating is applied to a flexible plastic film that is laminated to at least one surface of said front sheet.

10. The sealed unit of claim 8 including a flexible plastic film that is laminated to at least one surface of said front sheet, said flexible plastic film incorporating both UVabsorbing material and an antireflective coating.

11. The sealed unit of any one of claims 1 to 11 wherein said sheets are spaced apart by a distance of at least 2 mm.

12. The sealed unit of any one of claims 1 to 11 wherein said front and rear sheets are separated by a distance of at least 6 mm and where the sealed chamber is filled with an inert gas.

13.

The-sealed unit of any one of claims 1 to 12 wherein 4 18 said peripheral spacing and sealing assembly comprises a structural seal and a gas barrier seal.

14. The sealed unit of claim 13 wherein said structural seal is an inner seal positioned inwardly of said gas barrier seal.

15. The sealed unit of claim 14 wherein said structural seal comprises in part a barrier film tape with pre-applied pressure sensitive adhesive.

16. The sealed unit of claim 15 wherein said unit incorporates a paper artwork and where said barrier film tape features pre-applied, two sided pressure sensitive adhesive which structurally adheres together said flexible back sheet, a back mat board, a front mat board and said front glazing sheet.

17. The sealed unit of claim 16 where prior to application said barrier film tape includes three or more separate release liners.

18. The sealed unit of claim 13 where said gas barrier seal is positioned outwardly of said structural seal and comprises a tape with pre-applied polyisobutylene or butyl material.

19. The sealed unit of claim 14 wherein said structural seal consists in part of a foam tape with-preapplied pressure 19 sensitive side adhesive on the sides thereof.

20. The sealed unit of Claim 19 wherein said foam tape incorporates desiccant material.

21. The sealed unit of Claim 20 wherein said foam tape is made from silicone foam.

22. The sealed unit of claim 1 wherein two or more of said sheets are glass.

23. The sealed unit of claim 1 wherein said spacing-andsealing assembly incorporates desiccant material that is exposed to the interior of said chamber.

24. The sealed unit of claim 1 wherein said colored feature is printed onto a flexible film which is laminated to a cavity face of one or more of said sheets.

25. The sealed unit of claim 1 wherein said colored feature consists of multiple patterns applied directly to a cavity face of one or more of said sheets.

26. The sealed unit of claim 1 wherein said colored feature consists of strips of colored plastic film material adhered to a cavity face of one or more sheets.

27.

The sealed unit of claim 26 wherein said strips incorporate oxygenabsorbing material in sheet form.

28. The sealed unit of claim 6 wherein the composition of said oxygen absorbing sheet material comprises oxidizable organic compounds and transition metal catalysts.

29. The sealed unit of claim 7 wherein said oxygen absorbing material is incorporated in said spacer-and- sealing assembly.

30. The sealed unit of claim 7 wherein said spacing-andsealing assembly comprises a desiccant-filled spacer strip sandwiched between said sheets and located inwardly of the glazing edges, thereby creating an outwardly facing perimeter channel that is filled with sealant material.

31. The sealed unit of claim 30 wherein said oxygen absorbing material is contained within a channel formed in said spacer strip.

32. The sealed unit of claim 30 wherein said oxygenabsorbing material is incorporated as a fill within said spacer strip.

33. A sealed unit substantially as hereinbefore described with reference to the accompanying drawings.