NZ201257A - Mirror with a bonded foam backing:heat laminated flexible impermeable plastic skin on rear face - Google Patents

Description

2 012 57 Priority Date(s): ^.. .7/$ I Complete Specificat'on Filed: Class: 7SjJJ9.?S. .SQ.^P.M.

P.O. Journal, No: NEW ZEALAND PATENTS ACT, 1953 No.: Date: COMPLETE SPECIFICATION MIRRORS */We, CHELSEA ARTISANS LIMITED, a British Company, of Unit .2, Ferry Works, Summer Road, Thames Ditton, Surrey KT7 OQQ, United Kingdom hereby declare the invention for whichji / we pray that a patent may be granted tQ:»ne</us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) 2 012 - ja- This invention relates to improvements in or relating to mirrors and especially mirrors in which the transparent face backed by the layer of reflective material is intended to be laminated to a surface, for example a wall or a substantially rigid backing board.

It has been found that, particularly in large mirrors of this kind and especially where the transparent face is provided by a sheet of glass, there is a tendency for the product to fracture when exposed to an environment in which substantial variations in temperature are encountered; for example such as when the product 10 is used for cladding the outside of a building or is otherwise exposed to the elements and/or to direct sunlight. To overcome this defect it has been proposed to include a flexible and resiliently compressible layer of a polymeric foam which is bonded to the layer of reflective material and which in use lies between the mirror and 15 the surface to which it is to be laminated or attached; see GBA 2048166.

This foam layer absorbs the stresses developed during heating or cooling of the mirror and the surface to which it is attached due to the different coefficients of expansion of the mirror and the 20 surface, thereby reducing or preventing fracture of the mirror.

Further, where the transparent face is glass and this is fractured, e.g. by impact, the glass fragments tend to remain bonded to the foam layer, thereby reducing the danger of damage to property or persons by flying or falling glass.

The foam layer also provides the mirror with a valuable shock absorbance which increases its ability to withstand a blow without fracturing. 201257 Mirrors backed with such foam layers have therefore found rapid acceptance in the market.

It has been found however that where adhesives are used to bond such mirrors to the surfaces to which they are to be attached, 5 components of the adhesive tend to infiltrate the foam to the detriment of the foam, of the mirror itself and/or of the adhesive which may be used to bond the mirror to the foam. For example, where commonly available contact adhesives are used to adhere a foam backed mirror to a surface, solvents in the adhesive (or vapours 10 thereof) can pass through the foam and cause the foam to delaminate from the mirror.

According to the present invention, there is provided a sheet mirror structure adapted for bonding to a relatively flat support surface such as a wall or substantially rigid backing 15 board and comprising a transparent facing lamina backed by a layer of reflective material, said layer-backed lamina being bonded to a flexible and resiliently compressible layer of polymeric foam and the face of the foam layer on the opposite side to that to which the lamina is bonded being provided with a flexible substantially impermeable plastics skin which is laminated to the foam layer by the application of heat and the exposed face of which is capable of being bonded by ccnmon adhesives.

Preferably the substantially impermeable skin is a sheet, foil or film of impervious plastics material. 2C1257 m In a preferred embodiment, the skin may be of a | multi-layer nature, one layer providing the required degree of imperviousness and the other or another layer, which will be an 5 external layer, the means for effecting the bond with the foam layer. Thus, for example, the skin may be formed from a polyurethane-coated vinyl chloride polymer, e.g. PVC, sheet, film or foil. Such skin may be bonded to the foam layer via the polyurethane coating by the application of heat. An example of such a material is the polyurethane-10 coated PVC sheet sold under the trade name Velbex by Storey Bros., Braintree, Essex.

In yet another preferred embodiment, the skin may be an impervious film, sheet or foil of a plastics material which is inherently capable of being bonded to the foam layer by the application of heat. One 15 suitable example is polyurethane.

It may be found desirable to provide at least one face of the foam layer with a web which is bonded to the foam and which will prevent or inhibit the foam layer from stretching or otherwise deforming during its bonding to the other components employed in the production of the 20 mirror structure of the invention. The web, hereinafter referred to as a stabilising web, may be of any suitable material, e.g. flexible thermoplastics film or a textile e.g. of knitted or woven polyamide (nylon) or polyester.

The foam layer will normally be bonded to the reflective layer-25 backed lamina by a suitable adhesive. Preferably, however, there is provided between the foam layer and the adhesive a flexible moisture- 1 ® impermeable microporous membrane which will permit the escape of { 2 4 OCT J985"jj \\ > /' f* - V *.v 20125 . 4 - volatiles from said adhesive while preventing, when the mirror structure is in use, any water or moisture which enters the foam layer from contacting the adhesive layer.

The microporous membrane may comprise any film which is 5 impermeable to moisture and water but is permeable to gas or vapour; however it is preferably plastics. If a thermoplastic membrane is used, it can be bonded to the foam layer by heat, thus avoiding the need for another adhesive-applying step. The microporous membrane need only be a few microns, e.g. 10 to 15 microns, in thickness. 10 The said microporous membrane may also act as the above- mentioned stabilising web if it is attached to the foam layer before the latter is bonded to the reflective layer and is of a suitable material. However, the web and membrane may be different, if desired.

Examples of materials suitable for the foam layer include the 15 foams marketed by Dunlop Ltd of England as DF 113, DF 119 and, in particular, D8.

An example of an adhesive for bonding the facing lamina to the foam layer is SN 1501 marketed by Dunlop Ltd.

A suitable thickness for the foam layer is 0.1 to 0.15 inch 20 (about 2 to 4 mm) although larger or smaller thicknesses may be used.

The facing lamina may be of glass or plastics. When it is plastics, it may be a sheet e.g. of acrylic or a film e.g. of polyester. The facing lamina may be tinted. The reflective layer is generally metal, e.g. silver or copper.

One example of a mirror according to the invention is illustrated in the accompanying drawing which is a perspective view partly cut away to illustrate more clearly the various component layers of the product. 201257 In the embodiment illustrated, the mirror comprises a 3 mm thick transparent acrylic or glass sheet 2 provided in conventional manner, e.g. by silvering and coppering, with a layer 4 of reflective material. This is bonded by means of Dunlop adhesive SN 1501 (not 5 shown) to a 3 mm thick layer 8 of flexible and resiliently compressible foam, such as Dunlop DF 113, DF 119 or D8, to which a stabilising web 6 comprising a nylon scrim' has previously been bonded and which lies between the foam layer and the reflective layer, A sheet, film or foil 10 of impervious polyurethane-coated PVC 10 is bonded to the underside of the foam layer 8.

The mirror was manufactured in the following manner. First the sheet 10 of polyurethane-coated PVC (Velbex) was laminated to one face of the plastics foam sheet 8. The bonding of the Velbex was effected by placing the sheet in contact with the foam sheet with the 15 polyurethane-coated side contacting the foam, and then heating the composite structure to cause the polyurethane to soften and. adhere to the foam.

The nylon scrim 6 was then heat bonded to the free face of the foam layer and the foam layer then glued to the siLvered acrylic 20 sheet 2 with the scrim lying between the sheet and the foam.

The mirror was attached to a wall using a conventional contact adhesive which produced a strong bond between the mirror and the wall. Because of the impervious nature of the PVC skin the solvent of the adhesive did not permeate through to the mirror/foam interface and 25 consequently there was no danger of the bond between the mirror and the foam being weakened.

In a modification of the above mirror assembly, the polyurethane- 2 0125/ coated PVC sheet, film or foil 10 was replaced with a sheet, film or foil of polyurethane which was heat bonded to the foam sheet 8.

In a further modification, a sheet (not shown) of "Platinon", a flexible moisture-impermeable microporous plastics film sold by 5 Cole Plastics of England, was bonded between the acrylic sheet and the nylon scrim-coated face of the foam. 13 JUL 1982 ] ScBVEO

Claims (6)

201257 7 WHAT^WE CLAIM IS: ■^ESHTS

1. A sheet mirror structure adapted for bonding to a relatively flat support surface such as a wall or substantially rigid backing board and comprising a transparent facing lamina backed by a layer of reflective material, said layer-backed lamina being bonded to a flexible and resiliently compressible layer of polymeric foam and the face of the foam layer on the opposite side to that to which the lamina is bonded being provided with a flexible substantially impermeable plastics skin which is laminated to the foam layer by the application of heat and the exposed face of which is capable of being bonded by common adhesives.

2. A mirror structure as claimed in claim 1 in which the substantially impermeable layer is a sheet, film or foil of aainyl polyurethane-coated vinyl chloride polymer or polyurethane.

3. A mirror structure as claimed in claim 1 or claim 2 in which one face of the foam layer is provided with a stabilising web which is bonded to the foam.

4. A mirror structure as claimed in any one of claims 1 to 3 in which there is provided between the foam layer and the layer of adhesive employed to bond said layer to the reflective layer-backed lamina, a flexible moisture-impermeable microporous membrane.

5. A mirror structure as claimed in claim 4 in which a thermoplastic membrane is employed which is bonded to the foam layer by heat.

6. A mirror structure as claimed in claim 1, substantially as hereinbefore described with particular reference to the accompanying drawing. DATED THIS S 23-?/DAY Of 19^ A I PARK a SON