AU3226299A - The production of reflective surfaces - Google Patents

Description

-1- P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE

SPECIFICATION

FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: PETER BYRNE CONCEPTS PTY LTD Peter Byrne CARTER SMITH BEADLE 2 Railway Parade Camberwell Victoria 3124 Australia THE PRODUCTION OF REFLECTIVE SURFACES The following statement is a full description of this invention, including the best method of performing it known to us 2 The present invention relates to a method for the production of a reflective surface, which is particularly suitable in the production of signage or for obtaining decorative effects for use in interior or exterior design It is known to produce a reflective surface when producing signage or decorative cladding, where desired design effects are achieved from reflective properties.

It is sometimes required to produce a reflective surface on a lightweight substrate such as a plastics sheet, and when the substrate is in the form of a planar sheet, a satisfactory reflective effect can be obtained by laminating a reflective foil onto a surface of the sheet.

If the substrate sheet is shaped into a nonplanar configuration, it is difficult to obtain satisfactory lamination of a reflective foil onto a surface of the substrate sheet.

Depending primarily on the particular shape of the substrate sheet, in some instances it is impossible to obtain satisfactory lamination of the of a reflective foil.

It is therefore desirable to provide a method for the production of a reflective surface which can be applied to either planar or nonplanar substrates.

It is therefore an object of the present invention to provide a method for the production of a reflective surface which obviates the difficulty of obtaining satisfactory lamination when applying a reflective coating onto a nonplanar surface of a substrate.

According to a first aspect, the present invention provides a substrate with a reflective surface wherein the reflective surface comprises at least one metallic coating and said substrate is at least partially transparent. Preferably, the coating applied to one surface of the substrate is one of a plurality of coatings, and where the surface of said substrate is a planar or nonplanar surface.

According to another aspect of the invention there is provided a method of producing a reflective surface on a substrate comprising the step of applying at least one metallic coating to a transparent substrate by means of an arc spray deposition process whereby the coating, when viewed from the opposite side of the substrate, provides a reflective appearance.

KLM:HHF:#31489.DIV 27 May 1999 The arc spray deposition process which is known in the art is performed by striking an arc between two electrode wires of an alloy. A stream of air is directed through the zone of the arc to carry metallic particles from the two wires onto the substrate. Arc spray guns of this type are per se known. It is to be noted that the air stream does not form a high temperature plasma but is a cool airstream which carries molten particles onto the substrate and actually cools the particles.

It is preferable that the metallic coatings comprise a metallic material having a relatively low melting point.

In a preferred form of the invention, the metallic material is an alloy of tin and zinc. Tests have shown that use of tin, in amounts between 60% and 80% but preferably 70% is desirable, and that zinc in amounts between 20% and 40%, but preferably 30% provides a desired result.

In such an alloy, the zinc provides the reflectivity and the tin tends to lower the melting point of the alloy so that the alloy is able to melt at a relatively low temperature and is able to impact on the substrate after arc spraying.

The desired temperature is around 500 Celsius as at such a temperature, the metal droplets will not cause heat damage to the surface of a substrate having a relatively low melting or oxidizing temperature.

Electrode wires of suitable tin/zinc alloy composition are produced by Hobart Tafa Technologies, Inc. of 146 Pembroke Road, Concord, New Hampshire, USA under the designation "Tafaloy mould making wire 205".

During the arc spray deposition process the molten metal droplets impinge on the surface of the substrate as particles of a size preferably less than about 5 microns in diameter and fuse together upon impacting against the substrate surface to form a thin film which conforms to the shape of the surface.

In a preferred form of the invention a bonding coating is applied to a rear surface of the metallic coating. The bonding coating overlaps the edges of the metallic coating to reduce the likelihood of the metallic coating de-laminating from the substrate.

KLM:HHF:#31489.DIV 27 May 1999 The bonding coating may be a transparent coating of thin silane-type glass adhesive, a clear polyeurathane, or an epoxy system. An opaque paint or the like may be applied to the bonding coat. Alternatively, the bonding coating may be opaque.

In a further embodiment of the present invention an open pepper coat process may be used to achieve a bonding coating.

An open pepper coat involves spraying down a coat of 205 metal, blinding or covering between 50% and 90%, preferably 75% of the clear surface, as described above, then spraying on a clear coat of bonding material to bond or anchor the metal and bonding coat to the remaining exposed areas of substrate. Preferably, the clear coating is a substance suited to bonding to a plastic or glass substrate, such as epoxy.

While the clear coating is still tacky, the substrate is again sprayed with the 205 wire to fully blind over or cover the surface, which has the effect of covering those previously un-metalled but clear coated areas, into reflective areas giving the total surface an uninterrupted mirror finish.

A coloured reflective surface can also be produced using the above coating process.

In a further form of the invention it is desirable to use a bonding coating that is transparent, so that an opaque coloured paint can be applied over areas of the substrate that are free of the metallic coating. Use of an opaque coloured paint in this manner increases the variety of coloured finishes that can be produced.

Alternative methods that may be used include backcoating tinted glass or plastics with a translucent colour then when dry, treating the coloured surface with the 205 metal spray process.

The metal coating film thus applied is dull and grainy when viewed from the rear side of the substrate (that is, the side to which the coating is applied). However it creates a mirror face against the surface when viewed from the front side of the substrate.

As air is absent from the interface between the film and the surface of the substrate, the reflective surface of the coating does not deteriorate under the effects of oxidation. Therefore, the coated substrate is suitable for long term use, either indoors or outdoors.

KLM:HHF:#31489.DIV 27 May 1999 Although the metallic coating film does have adhesion to the surface of the substrate merely as a result of application by spraying using the process described, it is possible to remove the film by peeling the film from the substrate. A more durable bond may be achieved by applying to the rear surface of the film a bonding edge tape of clear glass film plastic, of the window tinting variety, which overlaps the edges of the film layer and prevents the edges from lifting and peeling from the substrate.

Edges of a curved undulating form require the clear tape film to be softened by applying with a hot air gun.

In order that the invention will be more readily understood embodiments thereof will now be described with reference to the accompanying drawings wherein: Figure 1 is a schematic cross sectional view of one embodiment of the invention; Figure 2 is a view similar to that of Figure 1 showing a further embodiment of the invention; Figure 3 is a view similar to Figure 1 but showing a still further embodiment of the invention.

Referring to Figure 1, a substrate 11 is a transparent substrate of glass, synthetic plastic material or the like. The substrate may be planar or it may be of any desired shape commencerate with the use to which the substrate is to be put.

A first reflective metallic coating 14 is applied to the rear surface 16 of the substrate 11 by means of arc spray deposition using two electrode wires of a tin/zinc alloy composition. The allow has between 0% and 60% tin and may be an alloy composition sold under the name "Tafaloy 205".

In the arc spray deposition process, an electric arc is drawn between the electrode wires and a stream of air is directed through the arc zone. Metallic particles which are melted from the wire electrodes by the electric arc are carried by the air stream and impinge on the rear surface 16 of the substrate 11. Preferably, the metallic particles have a size of up to about 5 microns in diameter, although particles of a larger size may be produced by the arc spray deposition process. When the metallic particles impact on the substrate surface 16, some particles merge together to form a KLM:HHF:#31489.DIV 27 May 1999 thin film of metal while other particles pepper the surface 16 to form a plurality of particle deposits.

A bonding coat 17 is then applied over the deposited metallic coating 14 on the rear surface 16. The bonding coat 17 is preferably an epoxy which bonds to the rear surface 16 and to the metallic coating 14. Other forms of bonding coat, such as a polyeurathane or a thin silane-type glass adhesive may be used.

After the bonding coat 17 has been applied, a second metallic coating 18 is deposited over the bonding coat to fully blind or cover the surface. It will be appreciated if the first metallic coating covers approximately 75% of the surface, the second metallic coating need only cover those areas which are previously uncoated although, in practice, the second metallic coating will generally cover a substantially larger portion of the surface.

Referring to Figure 2, in this embodiment, the first metallic coating is deliberately peppered onto the rear surface 16 of the substrate 11 and a bonding coat 17 is applied to ensure that the metallic coating 14 is held firmly adhered to the rear surface 16. With this embodiment, the spaces on the rear surface which are not covered with a metallic coating provides a decorative appearance to the substrate when viewed through the front surface. If desired, an opaque paint or the like may be applied to the bonding coat 17 to provide a colouring effect to the peppered metallised surface.

Although the metal coating 14 shown in Figure 2 is a randomly peppered coating, it is envisaged that a mask, stencil, masking tape or the like may be used so that the metallic coating is applied only to specific areas of the rear surface 16 to thereby provide desired decorative effects.

Referring to Figure 3, there is illustrated a further embodiment of the invention in which the metallic coating 14 completely covers the desired area of the rear surface 16, and the bonding coat 17 is applied over the metallic coating 14 and onto the rear surface 16 around the edge portion of the metallic coating 14 to thereby ensure that the metallic coating is firmly bonded to the substrate 11.

The bonding coat may be a thermochromic polymer which can change color on application of heat. The heat may be generated by applying an electrical current to KLM:HHF:#31489.DIV 27 May 1999 either the first metallic coating 14 or a second metallic coating 18, if present, to thereby cause the metallic coating to become heated by electrical resistive heating.

The bonding coat 17 in contact with the heated metallic coating can then be caused to change colour to produce desired decorative effect. By locating the electrical contact points at various parts of the metallic coating, different electrical current patterns can be caused to produce varying colour changes in the bonding coat.

It will be appreciated that more than two metallic coatings may be applied to the substrate 11. Bonding coats may be used between the metallic coatings if desired although it is also envisaged that the metallic coatings may be applied over each other without a bonding coat in between.

The best adhesive results have been achieved with an amine cured epoxy that has been modified to bond specifically to glass or synthetic plastic material.

The process creates new visual effects for a substrate such as glass or synthetic plastic material or other transparent of translucent material. One effect is a chrome effect which can be back-lit so as to give the appearance of a chrome surface. The back-lighting, however, emphasizes holes or spikes where the metal deposition on the substrate does not totally cover the substrate surface.

In order to obtain a reflective area of a defined shape within the borders of the substrate, prior to application of the metallic coating film to the rear surface of the substrate, a mask, removable masking tape and/or a removable shaped template may be applied to the rear surface of the substrate. The metallic coating film is then applied, and the mask, masking tape and/or template is removed. The bonding layer is then applied over the rear surface of the film and also over the areas left free after removal of the masking tape or template.

If, as is preferably the case, the bonding layer is itself a transparent layer, opaque paint applied to the outer surface of that layer over areas not covered by the metallic coating film will be clearly visible through the transparent bonding to provide a combination of metallic and coloured areas which can provide visually distinctive effects, for example for use as a sign.

KLM:HHF:#31489.DIV 27 May 1999 From the perspective of an observer viewing the substrate from the front, the presence of the thin, transparent bonding layer between the paint is not easily detectable and does not diminish the visual effect provided by the paint.

The process described enables a reflective coating to be applied to the surface of a transparent substrate of any shape. Although the process will normally be used with substrate in the form of a plastics sheet either of planar or nonplanar shape, it can also be used with a glass substrate.

It is desirable that a surface must be given a mild detergent wash rise and thoroughly dried before proceeding with applying any reflective metal spray film.

KLM:HHF:#31489.DIV 27 May 1999

Claims (21)

1. A method of producing a reflective surface on an at least partially transparent substrate, comprising the steps of applying a plurality of coatings to the substrate, one or more of the coatings being a metallic coating applied by a process of arc spray deposition.

2. A method for the production of a reflective surface as claimed in claim 1 where the plurality of coatings are of partial and non-partial coatings.

3. A method for the production of a reflective surface as claimed in claim 2 where a first coating is applied to the surface of the substrate and where this first coating is a metallic coating.

4. A method for the production of a reflective surface as claimed in claim 2 or claim 3 where the first coating is a partial metallic coating.

A method for the production of a reflective surface as claimed in claim 3 where said one or more metallic coatings is a non-partial metallic alloy with a relatively low melting point.

6. A method for the production of a reflective surface as claimed in claim 4 or claim 5 where the metallic alloy comprises a combination of tin and zinc in amounts between 60% and 80% tin and 20% and 40% zinc.

7. A method for the production of a reflective surface as claimed in claim 6 wherein the combination of tin and zinc is 70% and 30% respectively,

8. A method for the production of a reflective surface as claimed in claim 7 where a second coating is applied to the surface of the substrate.

9. A method for the production of a reflective surface as claimed in claim 8 where this second coating is a bonding coating which overlaps the edges of the first metallic coating.

A method for the production of a reflective surface as claimed in claim 9 where the bonding coating is in the form of a silane type glass adhesive, a clear polyeurathane, or an epoxy system.

11. A method for the production of a reflective surface as claimed in claim where a third coating is applied to the surface of the substrate. KLM:HHF:#31489.DIV 27 May 1999

12. A method for the production of a reflective surface as claimed in claim 11 where the third coating is a coloured coating.

13. A method for the production of a reflective surface as claimed in claim 12 where the third coating is a partial coloured coating, which deposits on at least some parts of the substrate free of the first metallic coating, and when the substrate is viewed from its other side, the coloured coating is visible.

14. A method for the production of a reflective surface as claimed in claim 13 where the coloured coating is an opaque coloured paint.

A method for the production of a reflective surface as claimed in claim 14 where a fourth coating is applied to the surface of the substrate.

16. A method for the production of a reflective surface as claimed in claim where the fourth coating is a metallic coating which deposits on the substrate free of previous metallic or coloured coatings.

17. A method for the production of a reflective surface as claimed in claim 2 where an open pepper coat of a first partial metallic coating is sprayed onto between 50% and of the substrate surface.

18. A method for the production of a reflective surface as claimed in claim 17 where a second coating being a transparent bonding coating is applied to the substrate.

19. A method for the production of a reflective surface as claimed in claim 18 where a third coating is applied being a full metallic coating.

A method for the production of a reflective surface as claimed in claim 19 where the third coating is applied when the bonding coating is tacky.

21. A method of producing a reflective surface substantially as hereinbefore described with reference to the accompanying drawings. DATED: 27 May 1999 CARTER SMITH BEADLE Patent Attorneys for the Applicant: PETER BYRNE CONCEPTS PTY LTD KLM:HHF:#31489.DIV 27 May 1999