AU643471B2 - Novel tamper evident closure - Google Patents

Description

COMMONWEALTH OF AUSTRA 4 3 4 7 1 Patents Act 1952 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number Lodged Complete Specification Lodged Accepted Published Priority NON-CONVENTION 55 Se

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See 55 S

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Related Art Name of Applicant THE KENDALL COMPANY oo*

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Address of Applicant Actual Inventor(s) Address for Service 15 HAMPSHIRE STREET,

MANSFIELD,

MASSACHUSETTS,

02048 U.S.A.

ROBERT W. ETHEREDGE, 111 LUZ ELISA THOMAS F.B. RICE CO., Patent Attorneys 28A Montacue Street BALMAIN NSW 2041 Complete Specification for the invention entitled: NOVEL TAMPER EVIDENT CLOSURE The following statement is a full description of this invention including the best method of performing it known to us/;ne:- The present invention relates to flexible tamper-evident tapes wherein the evidence of tampering is either a transfer of a pattern to the tampered product, revelation of a pattern on the backing of the closure, or 5 tearing of the closure and/or the product over a wide temperature range including temperatures on the order of -320 0 F where other so-called tamper-evident seals do not exhibit tampering when removed and replaced later.

O TeAmper proofing has been of concern throughout the ages in the .inancial and security sectors. However recently it has taken on new proportions due to tampering of food, cosmetic and pharmaceutical products.

*050 S The following patents are illustrative of the prior art, yet are by no means intended as a complete survey of the prior art.

The earliest patent, U.S. Patent No. 2,845,728 issued 0.0 to Huber, discloses a self-destroying label having pressure sensitive adhesive on one surface thereof. The principal object of this invention provided for a pressure sensitive label readily applicable to items of various kinds. Yet, when an attempt is made to remove such labels from the article, the label is damaged or disintegrates to a sufficient extent so that the condition of the label, if removed from one article and applied to another, readily and visibly will serve to indicate that the label has been tampered with. Essentially, the invention consists of weakening means comprising either interrupted rows of incisions or substantially continuous partial incisions.

-lA- I U.S. Patent No. 3,383,121 discloses a self-adhesive copy label comprising a laminate construction consisting of a first layer such as a sheet of paper, a second pressure sensitive adhesive layer, preferentially adhered to the first layer so that it separates with the first layer when the first and third layers are separated, and a third layer consisting of a sheet of material constructed to be impact sensitive in that it carries, in normally separate states, chemicals which intermix upon impact to produce a color 10 change in the impact area in or on the third layer itself.

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Thus the tamper evidence here is a color change.

U.S. Patent No. 4,082,873 issued to Williams discloses 5oo a "laminate comprising a transparent or translucent outer sheet having an information-containing pattern printed on its inner surface, the printed inner surface having a coating of pressure sensitive adhesive film coated thereon.

The affinity of the adhesive for the surface to which the laminated label is adhered and to the printed pattern is 2o greater than the affinity of the printed pattern for the outer sheet. Once applied to a substrate, if removal of the label is attempted, the label delaminates in a manner such that the outer sheet separates leaving at least a portion of the adhesive layer, having at least a portion of the printed pattern adhering thereto, adhered to the substrate." U.S. Patent No. 4,121,003 issued to Williams modifies Patent No. 4,082,873, by providing that at least a portion of the information-containing pattern be printed with an ink which is not dried into an integral film form so as to form a disruptable pattern when tampered with. Thus when the top sheet is delaminated from the adhesive, a portion of -2the pigmentation in the disruptable pattern adheres to both the top sheet as well as the adhesive layer, resulting in a "diminution of interruption of the coloration of the disruptable pattern on the top sheet sufficient to give visual indication of tampering." U.S. Patent No. 4,184,701 issued to Franklin et al discloses a label comprising "a laminate comprising a transparent or translucent outer sheet having an information 1O containing pattern printed on its inner surface, said printed film having a discontinuous coating of transparent plasticized organic polymeric material thereon, with said printed and coated surface having a coating of a color containing pressure sensitive adhesive film thereon." Upon 15 removal the label delaminates such that at least portions of S the colored adhesive in register with the transparent discontinuous plasticized polymer coating remain on the substrate to which the label is adhered. Thus the evidence of tampering is a visual change in at least portions of o background color.

0* U.S. Patent No. 4,608,288 issued to Spindler discloses a label comprising a cover foil with an adhesive layer laminated onto a base foil. The cover foil is made of a 5 material which is irreversibly deformable or easily breakable upon tampering. Moreover, the cover foil extends beyond the periphery of the base foil, thereby creating a safety rim which makes access to the base foil difficult.

3o U.S. Patent No. 4,652,473 issued to Han discloses a tape comprising a backing having an outer and inner layer, the outer layer having sufficiently high tensile strength to maintain its integrity when removed. In contrast, the -3inner layer is thin and deformable. Thus, evidence of tampering is present by way of delamination. Upon removal of the outer layer, it delaminates from the inner layer which in turn generally causes a partial stretching out of the thin inner layer. Moreover, the patentee suggests using printed or colored layers for additional evidence.

U.S. Patent No. 4,721,638, 4,746,556 and 4,763,931 all issued to Matsuguchi et al disclose a multilayered adhesive material comprising various separation forces so that when particular layers are separated they cannot readhere or cannot readhere as in the original state.

The primary disadvantage of the prior art, as (5 illustrated by the aforementioned patents, is evident at low temperature. At low temperatures, such as liquid nitrogen for example, the adhesive layers delaminate from the backing, thereby allowing for replacement without any evidence of tampering. Notably, while this delamination D0 does occur in tha three patents issued to Matsuguchi et al, lettering becomes evident when the material is replaced.

However, these tapes comprise multiple layers and thus are quite costly.

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The present invention obviates the disadvantages of the prior rt in an elegant and novel manner by providing for a S tamper evident closure at all temperatures.

-4- 5 SUMMARY OF THE INVENTION In a first aspect the present invention provides a tamper-evident adhesive tape for securing to a document container to provide evidence of tampering over a wide temperature range from above to below the Tg of the adhesive securing the tape to the document, said tape comprising a transparent backing layer carrying on one side thereof, in order: a discontinuous layer of deposits of a transparent barrier material bonded to the backing; a colored layer bonded to the backing layer in areas where there is no barrier material deposits, the barrier material preventing bonding of the colored layer to the backing layer in areas where the barrier material is present; and an acrylic pressure sensitive adhesive layer for securing the tape to the container where any evidence of tampering is desired, the bond strength between the backing layer and colored layer being greater than the adhesion strength between the colored layer and the adhesive layer securing the tape to the container both above and below the Tg of the adhesive layer, such that when attempt is made to remove the tape from the container to gain access to its contents, the colored layer will 25 remain with the backing layer in areas where they are :.:bonded while in areas where barrier material is present to prevent bonding, the colored layer will adhere to the adhesive layer to provide a colored pattern or image 0 evidencing tampering with the container which is visible to the eye, which evidence remains visible to the eye when an attempt is made to reapply the colored layer and *backing to the adhesive layer.

The present invention also provides a container with '"the inventive tamper-evident closure and a method for 35 revealing tampering of a container.

5a q- BRIEF DESCRIPTION OF THE DRAWING The figure is a diagrammatic cross-sectional view of f the novel tamper-evident tape of this invention.

DETAILED DESCRIPTION OF THE INVENTION As heretofore mentioned, the present invention is directed to a novel tamper-evident tape for applying over the flap or other opening in pouches, bags, envelopes or other containers for currency, security documents and the like, which tape will exhibit evidence of tampering if the tape is removed to gain access to the contents and then replaced. The tape will provide evidence of tampering over a wide temperature range from above to below the Tg of the adhesive layer adhering the tape to the substrate to be protected.

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99*9 *o99 a*o The invention will best be understood by reference to the accompanying drawing.

.As shown therein, the novel tamper-evident closure of this invention 10 will comprise a transparent backing 12 carrying, in order, a discontinuous layer of a barrier material 14; a colored laminating adhesive layer 16; and an adhesive layer 18, preferably a pressure-sensitive adhesive which bonds aggressively to the bag, pouch, envelope or other substrate. While not essential to the So practice of the invention, a per se known release sheet 20 is preferably provided to protect the adhesive surface from premature Scontact.

ct Backing layer 12 may comprise any of the per se known transparent and flexible backing or support sheets, e.g. a polyester such as polyethylene terephthalate, a polyolefin such as polyethylene or polypropylene, polycarbonate, a cellulosic ester such as cellulose acetate or triacetate, etc., including copolymers or blends thereof. It may be on the order of from about 0.5 to about 3.0 mils thick, 1.0 mil being preferred.

The barrier material 14, which is preferably app4e4- in a pattern but which may be randomly adhered to the backing, may comprise any material which bonds aggressively to backing 12.

*Examples of such materials include silicone, fluorocarbons, Quilon (trademark of DuPont), polyoctadecyl carbonate, etc., silicone being preferred. Barrier material 14, whose function is to bodtiAg or adereWnce.

preclude adhcrn of the underlying colored laminating adhesive layer 16 to backing 12 in areas of deposit, is -pIe erabkytransparent or translucent so that the underlying colored layer 16 may be seen therethrough when viewed through the transparent 6 backing. The barrier material deposits may, for example, be on the order of about 1.0 micron thick. They may be provided to the inner surface of the backing by per se known techniques such as gravure or flexible printing, spray coating, chemical etching and the like.

Co (ored -Lamiating adhoiRc Alayer 16 has a greater affinity for backing 12 than to the overlying adhesive layer 18. Accordingly, when effort is made to strip the tape from the substrate, layer 16 wants to stay with the backing.

6 Layer 16, which contains a color-providing material, e.g.

a non-migrating dye or a pigment, may comprise any of the known laminating adhesives. For instance, if backing 12 comprises polyester, colored layer 16 may comprise any of the commercially available polyester laminating adhesives to which the colorproviding materia,l has been incorporated.

S 56 The thickness of colored layer 16 may beA-e. the ordev of from about 0.1 to about 0.4 mil, a preferred thickness being about S0.2 mil.

Adhesive layer 18, laminating the tape to the substrate may comprise an acrylic pressure sensitive adhesive formulation aggressively adhering to the substrate. To increase flow and adhesion to the substrate, it preferably includes an adhesion promoter such as an unsaturated higher fatty acid having at least 12 carbon atoms, oleic acid being illustrative. Tackifiers and/or plasticizers may also be incorporated in the acrylic adhesive to increase adhesion.

In any event, it is critical to the practice of this invention, as will be explained in detail hereinafter, that 7 while acrylic adhesive 18 must adhere aggressively to the substrate, the bond or affinity between layer 18 and the overlying colored layer 16 must not be as great as the borF or affinity of layer 16 to backing 12.

In optional embodiments, layer 18 may further contain a non-migratory color-providing material contrasting with the color-providing material in the overlying layer 16. It may also contain a chemical reagent which, through contact with the skin, produces a traceable reaction product in the skin and/or on layer 18 itself.

0 In use, the tape will of course be applied over the mouth or other opening in the container or other substrate.

(S When the tape is removed above the Tg of layer 18, e.g. at ambient temperatures, so as to tamper with the contents, in '4areas where no barrier material is present, the colored (2 layer 16 will remain with the backingA as heretofore alluded to. However, in areas where barrier material 14 is present o K0 so as to preclude adhesion of colored layer 16 to the (Ov -er I I backing the colored layer will be stripped away from the so 1 Pyer 12A barrierA adhering to adhesive layer 18 which remains aggressively bonded to the substrate. This will in turn provide a colored pattern on the substrate in terms of adhered colorant from layer 16 and a reverse contrast image visible through the stripped-off backing in terms of the remaining colored layer and areas'where there is no colorant visible through the backing. Even when an attempt is made to re-apply the tape precisely to the substr[te, evidence of its removal will still be readily visible to the eye, due to adhesive distortion.

When the tape is removed below the Tg of the adhesive, e.g. by first spraying with liquid nitrogen, and then removing the tape, visual evidence of the tampering will also be exhibited in one or more of the following ways.

-8a i t i -i;Q^ First, when the tape is removed from the substrate, adhesive layer 18 delaminates from colored layer 16 except where barrier layer 14 is present. At these areas, colored layer 16 breaks from barrier layer 14 and transfers with S adhesive layer 18.

A second possible evidence of backing is liable to tear, leaving along with the evidence of tearing tampering, is that the an image on the substrate of the backing.

9a 'e *9 .4 *t 0 4 .4.44 A third evidence which may occur is a noticeable wrinkling or distortion of the substrate.

The following examples show by way of illustration and 15 not limitation the novel characteristics of the present invention.

Example 1

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Si ;o Layer Layer Layer Layer Ingredient Mylar* Silicone Polyester Laminating Adhesive 10% Blue Pigment Ethylacetate Based Acrylic Adhesive Oleic Acid Kraft Release Liner Thi:ckness 1 mil <1 "4 0.4-0.5 mil 0.1-0.4 mil 4 mils .4r .4 S as Layer 4 Layer 5 Tradorior'k (if, Duiorit -9ft. Example 2 Mylar was flexible printed with a silicone layer. The printed side was then overcoated with the laminating layer which was in turn overcoated with the adhesive layer.

Lastly, a Kraft release liner was applied to the adhesive side of the aforementioned film.

By way of recapitulation, the present invention offers b 0 (0 a tamper evident closure over a temperature ranging from S* +150 F to -320 o. Among the many tamper evident mechanisms are: transfer of a colored pattern to the substrate, revealing of a printed pattern on the backing,tearing of the backing, color change, wrinkling of the substrate, finger prints as well as transfer of color to tamperor.

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Claims (4)

1. 4. A tamper-evident tape as defined in any one of the preceding claims wherein the barrier material comprises silicone. A tamper-evident tape as defined in any one of the preceding claims wherein the colored layer consists essentially of a color-providing material and polyester characterized as being relatively soft and pliant so that under force of removal it will convolute or distort so that it cannot later by overlaid on the adhesive layer without evidence of its removal being visibly revealed.
2. 6. A tamper-evident method for revealing tampering of a container having an opening for access to insert or to remove an article within the container, comprising the steps of: inserting an article through the opening and into the container; and thereafter sealing the opening by applying over the opening a tamper-evident tape as defined in any one of claims 1 to
3. 7. A container having an opening for inserting or removal of an article, an article disposed within the container, and a tamper-evident tape as defined in any one 25 of claims 1 to 5 adhered across the opening cf the :container to seal the opening closed.
4. 8. A tamper-evident tape substantially as hereinbefore described with reference to the accompanying drawing. DATED this 13th day ofE September 1993 o* THE KENDALL COMPANY .Patent Attorneys for the eeo Applicant: F.B. R±iE CO. ^4