CA2029810A1 - Tamper evident closure - Google Patents

Abstract

P.F. 1075 A B S T R A C T

This invention relates to a tamper-evident tape comprising a transparent backing carrying in order, (1) a discontinuous layer of a barrier material preventing adhesion of the underlying layer to the backing, (2) a colored laminating adhesive layer having a greater affinity to the backing than to any other layer in the tape; and (3) an adhesive layer for aggressively securing the tape to the bag pouch or other substrate to which evidence of tampering is desired, which tape is tamper-evident over a wide temperature range.

Description

P.F. 1075 202981 0 NOVE~ TA~PER ~VID~NT CLOSUR~

Backqround o$ the Invention The pre~ent invention relates to flexible tamper-evident tapes wherein the evidence of tampering is ei her a transfer of a pat~ern to the tampered product, revelation of a pattern on tke backing of the closure, or tearing of the closure and/or the product over a wide temperature range i~cluding temperatures on the order of -320F where other so-called tamper evident seals do not exhibit t~mpering when removed and replaced later.

: Tamper proofing has been of concern throughout the ages in the financial and security sectors. However recently it has taken on new proportions due to tampering of ~ood, cosmetic and pharmaceutical products.

The following patents are illustrative of the prior art, yet are by no means intended as a complet~ survey of the prior art.

The earliest patent, U.S. Patent No. 2,R45,728 issued ~ to Huber, discloses a self-des~roying label having pressure ::~ sensitive adhesive on one sur~ace thereo~O The principal object o~ this invention provided for a pressure sensitive label readily applicable ~o items of various kinds. Yet, when an attempt is made to re~ove such labels Pr~m the : article, the label is damaged or disintegrates to a sufficient extent 50 that the condition of the label, if removed fro~ one article and applied to another, readily and visibly will serYe to indicat~ that the label has been . tampered witho ~sse~tially, the inYention consists of weakening means comprising either interrupted rows of incisions or substantially continuous partial incisions.

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U.S. Patent No. 3,3~3,121 discloses ~ ~elf-adhesive copy label comprising a la~inatQ con~truct~on consi~ting of a ~irst ~ayer such a~ a sheet of paper, a second pre~ure sensitive adhesive layer, prefer~ntially adhered to the first layer so tha~ i~ separate~ with the first layer when the first and third layers are separated, and a third layer consisting o~ a sheet of ~aterial constructed to be i~pact sensitive in ~hat it carrias, in normally separate states, chemicals whic~ intermix upon impact to produce a color change in ~he impact area in or on the third layer itself.
Thus the tamper evidence her~ is a color change.

U.S. Patent No. 4,082,873 issued to Williams discloses a ~laminate comprising a transparent or translucent outer sheet having an informa~ion-containing pattern printed on its inner surface, the printed inner sur~ace having a coating of pressure sensitive adhesive film coated thereon, The affinity o~ the adhesive for the surface to which the laminated label is adhered and to the printed pattern is greater than the affinity of the printed pattern for th~
outer sheet. Once applied to a substrate, if removal of the label is attempted, the label dela~inates in a manner such that the outer sheet separates leaving at least a portion of the adhesive layer, having a~ least a portion of the printed ~ pattern adhering th~reto, adhered to the substrate."
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U.S. Patent No. 49121,003 issued to Williams modifies Patent No. ~,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. ~hus when the top sheet is delamina~ed from the adhesive, a portion of ~2~
the pigmentation in the dl~ruptable pattern adheres to both the top shee~ as well a~ ~he adhesive layer, resulting in a "diminution of in~errup~ion of the coloratio~ o~ the disruptable pattern on th~ top shee~ suf~icient ~o give visual indication of tampering.~

U.S. Patent No. ~,18~,701 issued to Franklin et al discloses a label co~prising "a laminate co~prising a transparent or translucen~ outer sheet having an information containing pattern printed on i~s inner surface, said printed film having a di~con~inuou-~ coating o~ transparent plasticized organic polymeric material thereon, with said printed and coated surface having a coa~ing of a color containing prsssure sensitive adhesive ~ilm thereon." Upon removal the label delaminates such that at least portions of the colored adhesive in register with t~e transparent discontinuous plas~icized polym~r coating re~ain on thP
substrate to which the label is adhered. Thus the evidence of tampering is a visual c~ange in at leas~ por~ions of background color.

V.S. Patent No. 4,608,288 issued to Spindler discloses a label comprising a cover ~oil with an adhesive l~y~r laminated onto a base foil. The cover foil is made of a material which is irreversibly deformable or easily breakable upon tampering. ~oreover, ~he c~er foil extends beyond the periphery of ~h~ base foil, thereby creating a safety ri~ which makes access to the base foil difficult.

U.S. Patent No. 4,652,473 issued to ~an discloses a tape comprising a backing having an outer and inner layer, the outer layer having sufficiently high tensile strength to ~ maintain it~ in~egrity wh~n removed. In contrast, the : -3-inner layer is ~hin and de~or~able. Thus, evidencQ o~
tamparing i~ present by way o~ delamination. ~pon remov~l of the ou ~r lay~r, it dela~inate~ ro~ the inner layer which in turn generally cause~ a partial ~tretching out o~
the thin inner layer. ~oreover, ~ha pa~ent~ suggest~ u~ing printPd or colored layers for additional evidence.

U~S. Patent No. 4,721,638, 4,746,~56 and 4,763,931 all issued to Matsuguchi et al di~close a multilayered adhesive material comprising various separa~ion forces so that when particular layers are separated they cann~t readhere or cannot readhere as in the original state.

The primary disadvantage of the prior art, as illustrated by th~ aforemen~ioned patents, is evi~en~ 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 ~his delamination does occur in the ~hree paten~ issued ~o Mat~uguchi et al, lettering becomes evident when ~he material is replaced.
However, these tapes comp~ise multiple layers and thus are quite costly.

The present invention obviates the dicadvantages o~ the prior art in an elegant and novel manner by providing for a tamper evident olosure at all temperatures~

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In accordance with thi~ invention, th~ aforementioned disadvantages ~re obviated l~y providing a ta~per-evid~nt tape comprising a transpar~nt bac:king carrying in order, (1~ a discontinuous layer o a barrier material preventing adhesion of the underlying layer to the backing;
(2) a colored lamina~ing adhe~ive layer havin~ a greater af f ini~y to the bacXing than to any other layer in the tape; and (3) an adhesive layer for aggressively securing the tape to the bag pouch or other substrate tc~ which evidence of tampering is desired, which tape is tamper-evident over a wide temperature range.

BRIEF DESC~IPTION O~ THE DRAWI~G

The f igure is a diagrammatic cross-sectional view of the no~el tamper-evident tape of 'chis invention.

DETAILED DESCRIP'rION OF q~HE INV~TION

A~ heretofore mentioned! the present invention is directed to a novel tamper-evident tape ~or applyirlg ov~r the flap or other opening in pouche~, bags, envelopes or other c:on~ainers ~or currency, security documents and the like, which tape will exhibit evidence o~ tampering i~ the tape is removed to gain access to the contents and then replaced. The tape will provide evidence o~ tamperirlg over a wids temperature rang~ from above to belo~ the ~g of the adhesive layer adhering the tape to the substrate to be protected.

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The i~entlon will be~t be understood by re~erence ~o the accompanying drawing.

As shown therein, the novel tamper-evident clo~ure of this in~ention 10 w~ll comprise a transparent backing 12 carrying, in order, a discontinuous layer of a barrier material 14; a colored la~inating adhe~ive layer 16; and an adhesive layer 18, pre~rably a pressure-sensitiv~ adhesive, which bonds aggressively ~o ~h~ bag, pouch, envelope or other substrate. whil~ not essential to the practice o~ the invention, a per se known release sheet 20 is prefera~ly provided to protect the adhesive surface ~ro~ prematur~
contact.

Backing layer 12 may comprise any o~ the per s~ known transparen~ and fl~xible backing or support sheets, e.g. a polyester such as polyethylene terephthalat~, a polyolefin such as poly~thylene 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 O.S to about 3.0 mils thick, 1.0 mil being preferred.

The barrier material 14, Which is preferably applied in a pattern but which may be randomly adhered t~ the backing, may comprise any material which does~ 3 bon~ a9~r~sslvely to backin~ ~ Examples of ~uoh material~ ;nclude silicone, uorocarbons, Quilon ~trademark of DuPont~, polyoctadeGyl carbonate, etc., silicone b ~ pr~ferred~ ier material 14, whose function is to ~ c~~adherences of the ` 7;~
underlying colored lamina~iny adhe~ive layer 16 to backinq J
in areas of deposit, is preferably transparent or translucent so that the underlying colored layer 16 may be seen therethrough when viewed through the transparent --6~

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- backing. ~e barrier ~aterial depo~it~ may" for example, be on the order o~ about 1.0 ~!thick. ~ey may be provided to the inmler ~urface o~ ~backing by per ~ kno~n techniqae~ ~uch as gravur@ or ~exlble printi~g; spray coating, chemical etching a~ad the lik~.

La~ninating adhe~;ive layer 16 ha~ a greater aiEi~inity for backing 12 than to the~nde~ying adhes~re layer.
i~ Accordingly, when e~for~made to strip the tape from the substrate, lay~r 16 wants to stay with the backing.

Layer 1~, which contains a color-proYiding material, e.g. a non migrating dye or a pigment, Dlay co}~prise any of the known laminating adhe~;ives. For instance, if backing 12 comprises polyester, colored layer 16 D~ay c:olDprise any of the commercially available polyes~er laminating adhesives to whic21 the color-providing material has bPen incorporated.

The thickness of colored layer 16 may be on the order of ~rom about 0.1 to about 0. 4 mil, a pre~erred thickness being about 0. 2 mil .

Adhesive layer 18, la~inating the tape to th~ substrate may compriRe an acrylic pressure sensitive adhe~ive formulation aggressively adhering ~o the substrate. T~
increase ~low and adhesiorl to the subs~rate, it preferably includes an adhesion promoter such as an unsaturated hig~er fatty acid having at least 12 carbon ato~s, oleic acid being illustrative. Tackifiers and/or plasticizrs may also be incorporated in the acrylic adhesive to incre~se adhesion.

In any event, i~ is critical to the practic:e of this invention, as will be explained in d2tail hereina~ter, that \
~2 whils acrylic adhe~ive 1~ ~U#t adhere aggr~ssively to the substrate, the ~ond or a~inity between layer 18 and the overlying colored layer 16 mu~t not be as great as the af~inity of layer 1~ ~o backing 12~

In optional embodi~ent~, layer 18 ~ay further contain a non-migratory c310r-provid~ng ~aterial contrasting with the color-pro~iding material in the overlying layer 167 It may also contain a chemical reagent which, through contac~ with the skin, produces a traceable reaction product in the skin and/or on layer 18 itself.

In use, the tape will o~ course be applied over the mouth or other opening in the container or other substrate.
When the tape i5 removed above the Tg o~ layer 1~, e.g. at ambient temperatures, so as to tamper with the contents, in areas where no barrier material is present, the colored layer 16 will remain with the backing, as heretofore alluded to. However, in areas where barrier material 14 is present so as to preclude adhesion of colored layer 16 to the backing, the colored layer will be stripped away from the barrier, adhering to adhesive layer 18 whi~ remains aggr~ssively bonded to the substrate. This will in turn provide a colored pattern on the substrate in terms o~
adhered colorant from layer 1~ and a rever~e contrast ima~e visible through the stripped-off backing i~ terms of the remaining colored layer and areas where there is no colorant vi~ible through the bac~ing. Even when an at~empt is made to re-apply the tape precisely ~o ~he s~bstrate, evide~ce of its removal will s~ill be readily visible to the eye, due to adhesive dlst~rtion.

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.

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Firs~, when the t~pe is removed fro~ the substrate, adhe~;iv~ layer 18 dela~inate~ ~rom colored layer 16 except where barrier layer 14 is present. P.t these area~, colored layer 15 break from barrier layer 14 and ~rans~er~ with adhesive layer 18.

A second possible evidence of tampering, i~ ~hat the backing is liable to tear, leavi~g an image on the substrate along with the e~idence of tearing of the ~ackin~

A th~rd evidence which may occur is a noticeable wrinkling or distortion of the substrate.

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

Example 1 Layer Ingredient Thickness Layer 1 Mylar* 1 mil Layer 2 Silicone <1 ~Y
Layer 3 Polye~ter Laminating O.4-0.5 mil Adhesive 10~ Blue Pigment Layer 4 Ethyl~cetate Based 0.1-0.4 mil Acrylic Adhesive 5% Oleic Acid Layer 5 Kra~t Relea~e Liner 4 mils * Trademark of DuPont ' 9a 2~29~ ~
~ ylar was flexibl~ printed with a silicone l~y~r. Th~
print~d ~ide wa~ then overcoated wit~ ~he la~inating layer which wa~ in turn overcoa~ed wi~h ~he adhesi~e layer.
La~tly, a Kraf release liner was applied to the a~he~ive side of the a~orementioned film.

By way of recapitulation, t~ present invention offer~
a tamper eviden~ ClQsure over a tempera~ure ranging from +150F to 32~F. Amony the many tamper evident mechanisms are: transfer of a colored pattern to the substrate, revealing of a printed pattexn on the backing~tearing of the backing, color change, wrinkliny of the substrate, finger printF as vell as tr nsfer of color to tamperor.

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Claims

WHAT IS CLAIMED IS:

A tamper-evident closure comprising a transparent backing carrying in order, (1) a discontinuous layer of a barrier material preventing adhesion of the underlying layer to the backing;
(2) a colored laminating adhesive layer having a greater affinity to the backing than to any other layer in the tape; and (3) an adhesive layer for aggressively securing the tape to the bag pouch or other substrate to which evidence of tampering is desired, which tape is tamper evident over a wide temperature range.