CHARGE CARD

Abstract: A charge card is described which is preferably made with precious metal with upper and lower surfaces. The precious metal layers are adhered to the plastic sandwiched material by means of an epoxy resin formulation which is specially adapted to provide the required adhesion of precious metal layers to the plastic layers. A coating for the charge card is also described.

Description: CHARGE CARD The present invention relates to charge cards. For the avoidance of doubt the term charge card used herein embraces all possible kinds of card used in lieu of payment in cash or cheque. Examples of such cards include credit cards such as VISA (Trade Mark), AMERICAN EXPRESS (Trade Mark) and many cards for use in specific shops or debit cards such as SWITCH (Trade Mark). It is conventional to make charge cards from plastics material. Some types of card are very exclusive. It is quite common for such cards to have a gold or platinum coloured coating on the faces thereof. These so-called gold or platinum cards are very prestigious and are usually only given to high salary earners. According to the present invention there is provided a charge card made wholly or partly from a precious metal. The term precious metal used herein includes high value metals such as platinum, gold (at all carats) and silver. As indicated above, a charge card of the present invention may be made wholly of a precious metal. Alternatively, it may be made only partly of precious metal. Preferably the charge card is a laminate including one or more layers made of a precious metal and one or more layers made of other materials such as non-precious metals, plastics or any other material which is suitable. More preferably, a charge card in accordance with the present invention is a three-part laminate including outer layers made of a precious metal and an inner layer made of a plastics material. For example, the plastics can be the same sort of plastics as that used in conventional credit cards. The layers of precious metal may be bonded in any suitable manner to the inner plastics layer. For instance, the layers may be bonded together by means of an adhesive. Any suitable adhesive may be used including the sort of material sold under the trade mark SUPER GLUE. However, in order to have the necessary durability, flexibility and rugged finish, the aforementioned known adhesives were not found to be sufficiently highly reliable. Therefore, preferably, an epoxy resin formulation is applied to the precious metal layer in order to adhere it to the plastics. Such resin formulations include bisphenol epoxies and, preferably, bisphenol A. In a preferred formulation, the epoxy comprises a fundamentally two part system which also includes a diluent added to one of the two parts to increase the viscosity and handling of the resin. Advantageously, the card may also be finely coated with the epoxy formulation to give a durable, flexible and rugged finish. The epoxy formulation overcomes many of the problems found in adhering a precious metal layer to a plastics layer in accordance with the invention. Common adhesives such as SUPER GLUE™, although adequate for some purposes, have insufficient long term durability under different conditions to maintain adhesion of the layers. This results in peeling of the metal layer, usually at the edges, with resultant tearing and other damage. The preferred laminated charge card in accordance with the present invention may be provided with the usual "information" presented thereon, including the signature of the card owner and his photographic representation as well as other details such as the card number, expiry date and the hologram. This information may be presented on one or both outer surfaces of the inner plastics layer and may be seen through windows in the outer precious metal layers. Alternatively and preferably, it may be presented on the outer metal layers themselves, for instance, by suitable engraving processes including laser etching processes or alternatively by stamping processes. Advantageously, the epoxy formulation described is also suitable for adherence of the hologram to the gold surface together with the magnetic strip and, if necessary, the signature patch. The peeling and tearing problem previously described is particularly acute for the hologram because it comprises a very thin layer of plastic or other material but the resin formulations described have been found to overcome this problem, however, by coating of the card, with the hologram, magnetic strip or signature patch adhered thereto, with a fine coat of the epoxy resin formulation. It has also been found that curing of this fine coating at an elevated temperature causes an increase in clarity thereof which is necessary to maintain presentation. It is not entirely clear how the epoxy resin formulation effects such powerful bonding of the layer of the precious metal to the plastics material but it has been found that the addition of the diluent considerably enhances the bonding of the precious metal to the plastics material and, additionally, improves the finish of the product by providing the correct viscosity of resin. It is known that a chemical interaction takes place between the diluent and the two part epoxy formulation which provides the improvements and incorporates the diluent into the resin structure but it is not known why this is so effective in binding the metal and plastics layers. The advantage is further enhanced by the fact that the formulation necessary to produce satisfactory adhesion may also be used to apply the fine coat to the finished charge card surface. The formulation described, provides not only improved adhesion and finish but also these properties in a single formulation. Preferably, the diluent is added in the range of 0 to 5% but more preferably in the range of 1 to 4% and most preferably 2% of the total composition by volume. The bisphenol epoxy and modified amine catalyst may be combined in the range of 1:0.5 to 1:4 but preferably in the mix of 1:2 by volume. This ratio provides a semi-rigid formulation which permits the required flexibility of the charge card but provides sufficient rigidity to meet the necessary toughness requirements for charge cards. The bisphenol epoxy will usually contain epichlorohydrin and bisphenol A which together will comprise 99 to 100% of the bisphenol epoxy part. The modified amine catalyst would typically comprise triethylenetetramine , tetraethylenepentamine and terphenyl and these ingredients will each be in the range of 0 to 10%. The contents of the components may be varied within the ranges described to provide the finished properties required. The preferred diluent is an N-alkyl-glycidyl ether and most preferably N- butyl-glycidyl ether. A particular preferred charge card in accordance with the present invention includes an inner plastics layer and outer gold layers. The total thickness of the card is typically the same order of thickness (0.8mm) as that of a conventional charge card. A laminated charge card in accordance with the present invention may be in the form of an inner plastics layer and outer layers of gold or other suitable precious metal, the gold may extend around the edges of the charge card to conceal the presence of the inner plastics layer. Alternatively, to provide extra strength a perimeter gasket may extend around and partially overlap the edges of the charge card. It may also peripherally overlap the faces of the charge card to the extent that it conceals the edges of the precious metal layers and thus significantly reduces the likelihood of peeling. The gasket may be made of a plastics material and this allows a very strong plastic to plastic epoxy resin bond at the interface of the plastic sandwich layer and the gasket which thus provides enhanced strength. The gasket is also bound to the metal layer where it overlaps therewith by means of epoxy resin. The fine coat of epoxy resin can also be applied over the gasket if necessary. It may be necessary to reduce the thickness of the main body of the charge card so that the perimeter gasket version of the charge card conforms with the relevant standards. In order that the present invention may be more readily understood a specific embodiment thereof will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows one face of a charge card in accordance with the present invention; and Figure 2 shows the reverse face of the charge card of Figure 1. Referring to the drawings a charge card 10 is made to conventional size (55mm x 86mm x 0.8mm) in a forge from a precious metal such as gold, which are then placed to sandwich a plastic sheet of charge card dimension. The gold layers are each 200 micron thick and the plastic card is 400 micron thick. Variations in these thicknesses can be effected and these may be necessary in order to comply with ISO standards for charge cards. The variations in thicknesses may also be necessary in order to accommodate the final coating of epoxy resin on the charge card without exceeding the ISO standard thickness. The epoxy resin formulation used in the example is made from commercially available ingredients. The two part epoxy formulation comprises ECCOBOND* 45 clear (ECCOBOND is a registered trade mark of W R Grace & Co) and catalyst 15 clear. ECCOBOND 45 clear comprises an epichlorohydrin/bisphenol A formulation which makes up 99 to 100% of the product. Catalyst 15 clear is a modified amine catalyst which includes triethylenetetramine, tetraethylenepentamine and terphenyl. Each of these components is present as less than 10% of the composition of the catalyst by weight. A diluent, N-butyl-glycidyl ether, is added to either one of the parts of the two part mixture prior to mixing. After mixing of the two parts, the resin is applied to the plastic surface prior to application of the gold layer. A similar process is carried out on the reverse side and the card is cured at 65° Celsius for several hours. The ECCOBOND 45 CLEAR formulation and the catalyst 15 clear are mixed in the ratio of 100:200. The flexibility of the cured system may be adjusted by the user to suit the particular metal requirements by changing the ratio of the components. The cure may be effected at room temperature but it has been found that curing at an elevated temperature improves adhesion. The diluent is added to provide 2% of the overall mixture by volume but this may be varied to suit viscosity handling requirements. The same formulation is used in the above example to adhere the hologram, magnetic strip and, if necessary, the signature patch to the gold layers. Laser etching is then used to etch the gold to high definition and, optionally, the signature of the user may be laser etched or provided in the conventional manner by a signature patch and photograph. Advantageously, the card can be drilled to 600 micron to accommodate SMART card technology and can be embossed through ordinary credit card manufacture. Due to the use of precious metals, the cards are assayed at the Assay Office in the United Kingdom or at the appropriate office in other countries. The cards are then finely coated with epoxy resin after assaying the precious metal layer to give a durable, flexible and rugged finish. Tests have shown that the peel strength is an important factor if the card is to meet the required ISO, European and British standards. The number 11 attached to the card, the dates 12, 13 of first validity and expiry and the name 14 of the card owner can all be stamped or etched into the card from the reverse side of the card. The brand 15 of the particular type of card is etched onto the card or printed onto the card by screen printing and laser etching or stamping. The magnetic strip 16 is attached to the rear of the card using adhesive. A piece of paper 17 for the authorised signature of the card owner is likewise attached to the rear of the card using adhesive. It is conventional to secure holograms to charge cards in order to prevent forging. Such a hologram 18 may be secured in place by adhesive as described. It is to be understood that the above described embodiment has been made by way of illustration only. Many modifications and variations are possible. For example the dimensions of the card can be different, in particular the thickness. The thickness of the card is ideally in the range from 0.25mm to 1mm.

Claims: C AIMS 1 A charge card made wholly or partly from a precious metal. 2 A charge card as claimed in claim 1, wherein the card includes one or more layers made of a precious metal and one or more layers made of other materials. 3 A charge card as claimed in claim 2, wherein the card is formed from a three part laminate including outer layers of precious metal and an inner layer of a plastic material. 4 A charge card as claimed in any preceding claim, wherein the layers are bonded together by means of an epoxy resin adhesive. 5 A charge card as claimed in claim 4, wherein the epoxy resin comprises a two part epoxy based adhesive, the parts comprising a bisphenol based epoxy resin and a modified amine catalyst respectively. 6 A charge card as claimed in claim 5 wherein one of the two parts of the epoxy based adhesive has an N-alkyl- glycidyl ether added as a diluent. 7 A charge card as claimed in claim 6 wherein the diluent is added to one of the two parts prior to mixing of the two parts. 8 A charge card as claimed in any of claims 4 to 7, wherein the bisphenol based epoxy is an epichlorohydrin/bisphenol A epoxy. 9 A charge card as claimed in any of claims 4 to 8, wherein the modified amine catalyst comprises triethylenetetramine, tetraethylenepentamine and terphenyl. A charge card as claimed in any of claims 6 to 9, wherein the diluent is added in the range of 0 to 5% by volume of the total composition. A charge card as claimed in any preceding claim, wherein a fine coating of epoxy resin based adhesive is applied to the finished particle. A charge card as claimed in claim 11, wherein the formulation of the coating is the same as the formulation of the adhesive. A charge card as claimed in any of claims 4 to 12, wherein the epoxy resin based adhesive parts are mixed in the range of ratios of 1:0.5 to 1:4. A charge card as claimed in any preceding claim, which includes a perimeter gasket around the edges of the card to prevent peeling of the metal layers. A charge card as hereinbefore described with reference to the drawings.

Inventors: ROBERTS WILLIAM SHERBROOKE, ROBERTS, WILLIAM, SHERBROOKE
Applicants: ROBERTS WILLIAM SHERBROOKE, SHERBROOKE SECURITIES LTD, ROBERTS, WILLIAM, SHERBROOKE, SHERBROOKE SECURITIES LIMITED
Application year: 1995
Main classification: G06K19
IPC codes: G06K19