Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1993-01-12
1995-05-09
Ryan, Patrick J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
428173, 428200, 428202, 428204, 428688, 428914, 156230, 156247, 427147, B32B 300
Patent
active
054138396
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a transfer film for use, for example, with security documents.
Intaglio printing has been used for many years to provide security printing on documents. Such printing has been used to provide security patterns and the like on banknotes and in addition tactility.
More recently, plastics security documents such as credit cards have been developed onto which intaglio printing is not generally possible. These generally lack intaglio-like tactility properties.
In these cases, planar films bearing security indicia and patterns have been transferred using a hot stamping technique. These films are applied under elevated pressure and temperature to a surface in the form of an alphanumeric pattern, a crest, logo or the like. For example by transferring a metallised film, gold effect lettering can be created of a smooth nature.
Metallised foils can be embossed by stamping a coarse three dimensional pattern, using an engraved stamping face such as in EP-A-194042A but this does not provide intaglio tactility.
It is known to apply films by hot stamping in which there is a three dimensional pattern such as a holographic, optically diffracting relief pattern on an inner surface of the film. Such films have, after transfer, completely flat surfaces, exhibiting no surface roughness. The hot stamping process itself is likely to flatten any external relief which may previously have existed on that surface of the film which may be touched after its transfer.
Signature panels have been hitherto conveniently been applied to cards by screen printing and hot stamping methods. It is desired significantly to improve on the counterfeit resistance and forgery resistance of such panels. Paper panels are difficult to remove from cards but hot stamped coatings are even more difficult as they are thinner and have less internal strength.
The use of intaglio printing is well established as an anti-counterfeiting and anti-forgery measure but it has not been used before with hot stamp signature strips. Intaglio is however found on the relatively expensive paper panels, which can significantly increase the cost of a card.
U.S. Pat. No. 3,545,380 describes intaglio effects obtained on hot stamping signature panels but this is done by providing a discontinuous transfer according to the engraving in the stamping head. They omit portions of the panel. This is undesirable.
In accordance with a first aspect of the present invention a transfer film comprises a pattern defining layer having concavities defining an inverted relief pattern; and a retaining layer overlying and releasably filling the concavities of the pattern defining layer, the pattern defining layer being removable from the retaining layer to leave the parts of the retaining layer filling the concavities defining the relief pattern.
In accordance with a second aspect of the present invention, a transfer film comprises a pattern defining layer having concavities defining an inverted relief pattern, the concavities being releasably filled with a relief material; and a retaining layer overlying the concavities of the pattern defining layer so as to adhere to the relief material, the pattern defining layer being removable from the retaining layer and the relief material to leave the relief material defining the relief pattern on the retaining layer.
We have devised a new transfer film which can be applied using a flat, unembossed mandrel to a planar substrate using a hot stamping technique so that an intaglio-like pattern can be provided on the substrate.
The invention is particularly suitable for applying signature panels since a complete panel carrying a relief pattern can be laid down without using an engraved stamping head. A parallel surfaced hot stamping film is provided in which the pattern defining layer's surface has three dimensional characteristics. Thus, the present invention provides a transfer film which will allow the making of signature panels on plastic, financial transaction cards, by a hot stamping method, such signat
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Chatwin Charles E.
Walker Karen S.
Krynski W.
Ryan Patrick J.
Thomas de la Rue & Company Limited
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