IES950856A2 - A composite laser-etchable tamper-proof label - Google Patents

Abstract

A composite laser-etchable tamper-proof label which may be adhered to a surface and re-used at least once before being finally adhered to a surface in a tamper-proof manner. The label has an upper layer of a brittle laser-etchable acrylic composite material which is bounded on its underside, by means of an acrylic adhesive, to a silicone-release coated polyester film. This film is coated on its underside with a coating of a pressure-sensitive acrylic adhesive, which has a controlled level of clean removability so that it can easily be detached from a surface to which it is bonded. Also, the upper layer can be released, without damage, from the silicone coated polyester film <Fig.2>

Description

A COMPOSITE LASER-ETCHABLE TAMPER-PROOF LABEL Technical Field The invention concerns a composite laser etchable label.

Background Art Labels made from a film which is etchable or engravable by means of a laser are known. The labels may be used as nameplates, rating plates, information plates, identification plates, inventory labels, barcode data carriers, and the like. The labels are made from two acrylic films of different colours, e.g. black on white, bonded together intermolecularly. An electronically controller laser beam is used to cut through the top thin layer of acrylic at high speed to give a high contrast inscription. The labels may be applied by manufacturers directly to products, spare parts and to packaging. To provide the necessary adhesive properties, the label includes a modified acrylic adhesive layer.

The acrylic film is very brittle and its composition is such that once the known labels are adhered to a surface they cannot be removed without the label breaking up. This is intentional and offers the advantage that the labels are tamper-proof and cannot be removed without destroying the label. This provides protection against theft, forgery and counterfeiting.

However, this advantage of the known labels that they destruct on removal can cause problems for manufacturers who may wish to temporarily remove the labels from a product, e.g. to insert the label in a laser printing machine, for the addition of an inscription to the labels, during a manufacturing, assembly or inspection process. To replace the label completely is very expensive due to the high cost of the composite acrylic material. OPEN TO PUBLIC INSPECTION 1S99S p 1 g_—______ UNDER |WT OKrOT.F ZI&o i SECTION 28 AND RULE 23 Π jjot j JNL. ΝΟ.../.Τ.3Λ. . OF 20/3/^4 950856’ - 2 Ob.iect of the Invention It is an object of the invention to provide a composite laser-etchable tamper-proof label which can be adhered to a surface and reused at least once before being finally adhered to the surface in a tamper-proof fashion.

Summary of the Invention Accordingly, the invention provides a composite laser-etchable tamper-proof label which may be adhered to a surface and re-used at least once before being finally adhered to a surface in a tamper-proof manner, comprising an upper layer of a brittle laser-etchable acrylic composite material, bonded on its underside, by means of an acrylic adhesive, to a silicone-release coated polyester film, which is coated on its underside with a coating of a pressure-sensitive acrylic adhesive.

Suitably, the polyester film is a clear polyester film. The pressure-sensitive acrylic adhesive on the backside of the polyester film may be protected, until used, by means of a release liner, e.g. a semi-bleached kraft liner.

In use, the upper layer may be laser etched with desired information and, after removal of the release liner, the label may be temporarily adhered to the surface of a product by means of the removable pressure-sensitive acrylic adhesive.

The whole composite label may be peeled off the product, several times as desired, for further laser etching.

When it is desired to permanently attach the label, in a tamper-proof manner, to a surface of a product, the upper layer of the brittle laser-etchable acrylic composite material may be removed easily from the silicone-coated polyester film, and adhered by the acrylic adhesive in a permanent position. Thereafter if any attempt is made to remove the tamper-proof label it will break-up. 950856 - 3 Brief Description of the Drawings An embodiment of the invention is hereinafter described with reference to the accompanying drawings, wherein; Figure 1 is a front view of a composite label of the invention; and Figure 2 is a side view, to a greatly enlarged scale, of the label of Figure 1.

Detailed Description of the Preferred Embodiment Referring to the drawings a composite laser-etchable label construction comprises an upper layer 1 of a brittle laser etchable acrylic composite material. This material is made from two acrylic films of different contrast colours bonded together intermolecularly. The material is laser engravable as explained above. The surface film may be black or silver on a base which is white or black respectively, such that when the laser cuts through the surface film a high contrast inscription is obtained. Other colour combinations may be used. A suitable material is that available commercially under the trade name TESA 6930 from Beiersdorf AG.

TESA 6930 is a high performance laser etchable acrylic film composition which is highly brittle so as to be tamper evident and which breaks-up if removal of the label is attempted after final adhesion to a surface as hereinafter described. Suitably, the film has a thickness of 65 microns and a weight per gm of 100g/m2.

The upper layer 1 is provided on the underside thereof with an adhesive layer 2, which is a acrylic resin based adhesive. A suitable adhesive is the modified acrylic adhesive, Cello 331435 commercially available under the trade name TESA 6930, referred to above. The combined thickness of the film layer 1 and adhesive layer 2 is preferably about 0.09 mm.

The upper layer 1 is adhered, by means of the adhesive layer 2 to the upper surface of a clear polyester film 3. The upper surface of the 0β 5 β - 4 polyester film 3 is coated with a silicone release material to ensure low adhesion and clean removability. Thus, the upper layer 1 can easily be peeled-off the polyester film 3 when desired. The polyester film 3 is provided on its underside with a coating 4 of a removable pressure sensitive acrylic adhesive.

Suitably, the polyester film 3 is commercially available from Flexcon Company, Inc. under the trade name Flexmark 150 SC-9. The film 3 may have a thickness of about 1.4 microns. The adhesive coating 4 suitably is also available from Flexcon Company, Inc. under the trade name Flexmark V-302LP adhesive. It has a controlled level of clean removability. Suitably, it has a thickness of about 0.8 to 0.9 microns.

The acrylic adhesive coating 4 is preferably backed with a release liner (now shown) which may be a semi bleached kraft liner.

When it is desired to use the composite label of the invention, the release liner may be peeled off and the label temporarily adhered to a surface by means of the adhesive coating 4. Because this is a removable adhesive, the label may be removed for further etching by stripping it from the surface.

When the label is to be finally attached in a tamper-proof manner to a surface, the upper layer 1 and adhesive layer 2 are easily removed from the silicone coated polyester film 3. The adhesive layer 2 of the upper layer 1 is then permanently bonded in a permanent position on the product to be labelled. Thereafter, the layer 1 cannot be removed without damage to the layer 1.

As shown in the drawings, the polyester film 3 is longer and/or wider than the film 1.

Claims (5)

1. A composite laser-etchable tamper-proof label which may be adhered to a surface and re-used at least once before being finally adhered to a surface in a tamper-proof manner, comprising an upper layer of a brittle laser-etchable acrylic composite material, bonded on its underside, by means of an acrylic adhesive, to a silicone-release coated polyester film, which is coated on its underside with a coating of a removable pressure-sensitive acrylic adhesive.

2. A label as claimed in Claim 1, wherein the polyester film 1 is a clear polyester and the pressure-sensitive acrylic adhesive coating is provided with a release liner.

3. A label as claimed in Claim 1 or Claim 2, wherein the pressure-sensitive acrylic adhesive coating has a controlled level of clean removability so that it can easily be detached from a surface to which it is bonded.

4. A label as claimed in any of the preceding claims wherein the polyester film is longer and/or wider than the upper layer.

5. A composite laser-etchable tamper-proof label substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.