Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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
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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
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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
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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
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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
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~ 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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