Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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' ' MARKING ~~LEMENT
w The present invention relates to a yanking element for
use ,in conjunction.with a product which is reguixed' to be
maintained under a particular temperature or
temperature-time condition. '
There are many products which need to be stored under
conditions such that a particular temperature limit~.is not
exceeded,. or at least is not exceeded for longer' than a
predetermined time. For convenience, ' both~v of these
conditions are referred to generically herein as the pre-
defined temperature condition. Generally the temperature
limit will be a maximum .(rather than a minimum)
tempe.~ature~. ~ . . ' . . '.
.Particular examples are certain types of food product
that.~have been pre-cooked or processed by 'freezing,
irradiation, partial cooking, freeze drying or steaming (or
other food processing procedures). If such products are
not-stored in accordance with the pre-defroad temperature
conditions than there is ,the danger of contamination by
organisms which are injurious to human health. This danger
is not removed by subsequently storing the' product below
the temperature maximum. Further examples of products
which may need to be stored in accordance w~.th pre-defined
temperature conditions are certain pharmaceuticals which
would otherwise deteriorate.
Currently, the purchasers of such susceptible products
are not able to determine whether the product has been
stored in contravention of the pre-defined conditions. For
example, frozen food purchased in, say,.a supermarket may
be adequately frozen ~t the time of sale but the purchaser
is unable to tell whether the food has previously been
inCOrrectly stored. This has the potential health
disadvantages mentioned above.
According to a first aspect o~ the present invention
there is provided a marking element for indicating whether
;a pre-defined temperature condition has been maintained,
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comprising a first material.capable of flowing above a
predetermined temperature separated from a second absorbent
material by a barrier layer (preferably impervious), the
. f first and second materials being' such that when. the .barrier
layer is punctured and the predeterminedvtemperature is
exceeded the first material flow's::along the second.material
~to produce a detectable change. . ~ ~. '
Preferably" the marking element i.sw constructed such
that .the first flowable material is provided::,:adjacent one
end of an elongate channel and ( at that Enc. of .t~ie~ channel )
is separated by said barrier layer from the absorbent
material which extends along the channel. Thus when the
baxrier layer has been punctured and the predetermined
temperature has been exceeded the first mater~ial.flows
along the .channel producing said .detectable change. The
' extent to which the first material f lows, alo~~g the: channel
( and this extent of~ the detectable change a~lon~g ~ the
channel) is an indication of the total time; at which the
marking element .has been apove Cne preae~ermmeu
temperature. , . .
', A particularly suitable~way of producing~the~~marking
element as described in the previous paragraph is to.print
a layer of an ink on to a carrier sheet such that the
channel is formed in the ink. The absorbent material may
be laid in positzon along the channel and then.overxaid by
a film providing the barrier layer. The first material may
then be provided in the region of the barrier layer above
the absorbent material and the whole then overlaid by a
further f film having a melting point higher than that of the
barrier layer. In this way it~is possible to use a~ probe
heater to a temperature above~,the melting point of the
barrier layer but belaw that of the outer film ~.ayer
whereby the barrier layer is selectively .punctured to
"activate" the label..
Ideally the elongate channel is formed at one end with
an enlarged"reservoir" region in which the first material
is received.
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Preferably the detectable: change is a vcolaur change so'
that any flow of the first material: as. a~. result of the
,predetermined temperature being exceeded::.i.s immediately
visible. . ~ - ... .
The first material may ~comprise:a polymeric material
which reversibly fuses above a desired t.emperature~, e.g., a
thermo-reversible wax. It will of course~be appreciated
that the material to be used will.be selected having:: regard
to the desired temperature of fusion, and that for.any one
. type of polymeric material it is~possible to~haye a range
of fusion temperatures depending on the mole~cular~wW3ght of
the material : Inorganic salts. ( a .'g = sodium or potassium
chloride) can also be incorporated in .the polymeric
material for providing variationwin temperature .of fusion.
The absorbent material, may fox example .be .paper or a
part~.culate material (e. g. kieselguhr)~
The detectable change rnay be produced in a number of
ways. For example, the first material may include a dye
which (during f ldw of the first material) causes the
.absorbent material to become dyed: and therefore coloured.
.Alternatively, the detectable change may be a colour change
resulting from an irreversible chemical reaction. Thus the
first and second materials ma,y incorporate ~x'espective
chemical reagents which wheat in contact react together to
produce a colour change.
According to a second aspect of the present invention
there is provided a marking element f or indicating whether
a pre-defined temperature condition has been maintained,
the marking element comprising an elongate indicator track
along which a detectable change (preferably a colour
change) occurs when the marking element is above a pre-
determined temperature, the length of the change being
representative of the time fox which the marking element is
above said. pre-determined temperature.
Preferably the marking element comprises a_ carrier
layer on one face of which is laid a coating in which the
indicator track is provided. To this end, the indicatoz
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track may include an'.absorbent mater~ialv:along which a
colour is developed, as.described f or~the fiesta aspect of
the invention. The reverse side of theca=Tier layer.may
be adhesively coated for _fixing.~ the marking element to a
product for which the temperature storefe.'cbnditions. are to
be , monitored : ~ .. . . . .,. , .. ~ . .
The invention will be further describedvby~ way of
example only with reference to' the accompanyi~rig 'drawings,
in which : ~. ~ ~ . - '
Fig. 1 is an exploded perspective~,view of one
embodiment of label in accordance with 'the invention; and
", . ~ ~ Fig. 2 shows the label after ' storage above the
permitted temperature.
The construction of the~~habel 1 will bewdescribed by
'reference to ,its method of production.
' A carrier sheet 2°(which'~is adhesively coated on its
reverse face) is printed 'with' an ink layer.3 (e.g. a
- polymer ~ based ink ) which is ~ such that r ~'a layer 3 of
predetermined thickness is'haid down. Layer 3 is shown as
?~eirig generally rectangular but doe's- '.include ~~a circular
aperture 9 adjacent to one, end of a ~ longitudinally
extending rectangular channel 5. A plurality of
rectangular ink layers 3 may be printed on to the carrier
sheet 2. The layer 3 may, f or example be white.
An absorbent paper wick b is then laid completely
along the length of channel 5, the wick 6 being of
sufficient length so as to extend over into the aperture 9
. where the~wick terminates (fee inset to drawing)'. Instead
of a paper wick it is possible to use a powder wick, e.g.
of kieselguhr. Furthermore, ~a~lthough Fig. 1 shows the
channel 5 opening ~.nto aperture 4, it is possible for there
to be a barrier of the ink 3 between the end of channel 5
and the aperture 9. In such a case, the wick 6 may simply
extend over the barrier.
In the°.next stage of manufacture, a clear layer 7 of
a heat shrink film is laminated~on to the ink layer 3. for
convenience,~the drawing shows layer 7 as being coterminous
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WO 9?J08113 PGT/GB91I01879 ..
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with layer 3 but in p~racti~ce a" singJ:e layer ? may be
provided to overlie all of ~ the layers ~3 ~. v
An amount .of a temperature 'condition indicator
material 8 is then introduced°irito'~aperfure~~4vand "sits" on
the layer 7 above the.wick~6.. This matexial is one wh~.ch
is of a viscosity such that the::material does not flow (at
least to any substantial. extent) below a 'predetermined
temperature,.,but will be capable of flowih'y along the wick
6 above this temperature: Th'e predetermined aemperature is
the temperature above which a prod~uc~t (with : which the
finished label will be associated). should.not'~'be stored, or
at least not stored above the temperature.f~or more than a
predetermined time.
The material 8 will generally be coloured, a.g. by the
incorporation of a dye therein. A red dye~is particularly
' suitable tar:use in conjunction with a~~white layer 3.
In the final stage of~~manufaeture, a ~ further clear
layer 9 is applied. This'layer'.9.may of course be a single
layer overlying all.of the layers 3.
Layer 9 is of a material which melts (or softens) only
at a higher temperature thap does layer ?. This latter
layer may for example be one which melts or softens at 100
to 120°C. furthermore, layer 9 may be printed with indicia,
such as the scale 10 and' other information e.g. company
name (not shown).
In use, the label is attached to the packaging of a
product whose storage temperature is to be monitored. The
label. is then activated by the application of a point
source of heat. This can be achieved by using a flat
pointed probe of 2-2.5 mm in diameter heated to at least
100°C but no higher then 120°C ~(a hand held soldering iron
will suffice if it can be controlled to the desired
temperature). The flat pointed probe is applied within
the circular area of the label and should be held in
position fox 0.5-1 mseaonds. As a 'result, layer ? is
punctured so that material 8 is able to come into contact
with the wiek 6.
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WO 92J08113 2 ~ (~ ~ ~ ~ ~ ~ 1'GT/GB9'1 /01879
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. Once activat.ed~,; the. label must be maintained: below the
specified storage.~temperature for the '. product.
If the temperature at which~the~.product is stored
. .
rises above the predeterminedwtemperature then the~material
8 will become less ,viscous ~ aid taiLl be~ capable of f lowing
along the wick, 6 : .The- niateriah. .:8 will . continue to f low
along the wick for ~so, long as they predetermined temperature
is exceeded. This. will result in tfie. wick becoming
indelibly coloured ~ over a part of its lerrgth~ extending f rvm
~.ts end adjacent aperture 4 (see. Fig. 2) .; zt wihl be
appreciated that in the event of the product being stored
above the permitted temperature and. then returned to below
the permitted temperature, the material 8 increases in
viscosity to prevent movement along the wick 6 although the
indelible colouring of.the~,wick 6 is maintained. If the
product should then once again bew,st~ored above the
permitted, temperature, ;the viscosity.. ofmaterial 8 will
decrease and the material.Carr advance further along the
Wick. ' , ; , . , .
A measure ,of the length .of, time for which the
temperature has been exceeded maybe obtained by reference
to the scale 10, the graduations of which may be
representative of the number of minutes,exposure above the
predetermined time. ~It is obviously an~easy matter to
inspect the scale visually to obtain .a representation of
the total time that the product has been stored above the
predetermined temperature. If this time is excessive then
the product may be discarded.
It should be appreciated that the labels 1 may be used
in a number of ways. ~'or example, the label may be
attached to the packaging of individual products so that a
purchaser of the product (e.g. in a supermarket) can
determine the time for w~:ich the product has been stored
above the permitted tempera3ture_ Alternatively, a label
mar be attached to a carton in which the products are
delivered to (say) -a supermarket. In this case, the
sapez~ta~'ket persr~nnel are able to de;.ide whether the
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product has been stored above .the permitted temperature for
too long . , _ .
The marking element according.to the invention may
also take a number af'forms other than t hat illustrated in
the accompanying drawings. ~~
For example, the marking element may comprise a
backing paper, a .paper. ,strip f arming a Wick which is
positioned on the.backing~paper, a heat sensitive laminate
applied aver the, backing paper and. paper strip:, 'a paper pad
positioned over one end of the paper strip and containing
the indicator material, and a final laminate to seal the
system.
Furthermore,. it is not essential that the marking
element be used as.an: indicator of the time for which the
product has been. stored, above a. particular temperature.
The marking element may be used, f or example, merely to
indicate that.a particular storage temperature hay been
exceeded. For example:, the marking element may comprise a
circular paper pad j E.ixed to a~ support ) overlaid by a heat-
sensitive polyrner.,layer between which an upper laminate
layer is sandwiched to the indicator material. To use the
marking elementr the ,heat sensitive polymez~ layer is
punctured as described above. If the marking element is
subjected to a temperature above that at which the
indicator material will. flow, then this material flows into
the paper pad and. provides an indiction that a
predetermined temperature has been exceeded.
