GB2617827A

GB2617827A - Printed time-temperature integrating packaging system

Info

Publication number: GB2617827A
Application number: GB2205432.4A
Authority: GB
Inventors: Robinson John; Baker Richard; Campbell Joseph
Original assignee: Oli Tec Ltd
Current assignee: Oli Tec Ltd
Priority date: 2022-04-12
Filing date: 2022-04-12
Publication date: 2023-10-25
Also published as: GB202205432D0; WO2023199111A1

Abstract

A printed time-temperature integrating packaging system comprises at least an initiator source material 602 and a diffusion medium 603, both printed onto a base layer 601, said base layer optionally being either a packaging material or a separate label suitable for adhesion to a packaging material. Upon activation said initiator source material diffuses through said diffusion medium and causes a visible change thereto, allowing an observer to track the time-temperature history of the package. A curable monomer mix 501, fig. 1 may be printed onto a moving web and cured to form an initiator chamber and a mixing / diffusion chamber, with appropriate gellable materials then printed into the chambers, or the initiator source material 602 and diffusion medium 603 may be printed directly onto moving web 601. The initiator source material and diffusion medium may comprise anhydrous gel materials. The time temperature indicator may be activated by application of physical pressure.

Description

Printed Time-Temperature Integrating Packaging System The present invention relates to a time temperature integrating packaging system, and a method of constructing a time temperature integrating system. The present invention has particular, but not exclusive, application to indicating when a perishable product may be past its best.

Background

There are a number of active labelling systems both on the market and within the patent literature wherein the label remains inactive until such time as a user (be that a manufacturer, packaging supplier, retailer, distributor or end-point user) activates said label via the application of pressure (be that via a machine/applicator or manually, with a finger/thumb, or by two reactive layers being brought into intimate contact via/during a lamination process).

DeltaTrak sell a range of products collectively under the Trademark TempDot (TM) that monitor time/temperature progression and or alert a user to the fact that a labelled product has been exposed to temperatures beyond a pre-determined threshold temperature. The precise details of the activation mechanism are unclear, however DeltaTrak's website has the following to say: Activation must occur above the defined temperature threshold of the label. If room temperature is not above the defined threshold, the TempDot label must be heated above the threshold temperature. Squeeze the blister on the indicator to activate.

Once the label is successfully activated, the first window will be completely filled with coloured dye and the word "On" will be visible to indicate the label is active. Note: All of the dye in the START button must be squeezed out of the blister. Labels that are not immediately used after activation will need to be stored below the product stop temperature to prevent false indication of temperature abuse.

After activation, place the label into an environment that is at or below its specific stop temperature for a minimum of 1 hour. Stop temperature can be found on the product specification sheet. 1.

Remove the adhesive liner from the back of the label and adhere it to the product. Note: The product to be monitored must already be below the defined temperature threshold.

There are clear limitations with this system, mainly the requirement for activation to occur above a given temperature threshold, the necessity for the entirety of the contents of the 'blister' to be expelled into the first window and the requirement for the label to subsequently be stored at or below a second given temperature for at least one hour prior to it being adhered to the object for which temperature tracking is required.

US2016033938 (VISION WORKS IP CORP) describes a 'timing system' based on an anode and cathode separated by an electrolyte. Whilst the patent is directed to the broader system, in para 20 of the description it is stated that "...The timing device is activated when a consumer applies pressure to the protrusion thereby breaking the barrier and depositing the small quantity of electrolyte into contact with the main body of the timing device and activating the timing device " W02017086883 (KEMIJSKI INST) describes an alternative, multi-layer label construction wherein two components are brought together by the removal of a pull out 'barrier' layer. Whilst not strictly speaking a 'pressure activated' system, it does demonstrate some of the other approaches available to achieve the desired outcome (an end user initiating the mixing of multiple components to 'activate' a label).

GB2485420 (PIRTSEM IT LTD) describes a lower threshold temperature indicator label with optional pressure activation. The activation means are not described in great detail (although incorporate by reference the activation means described in US7232253) but are described as any of a pre-filled blister adjacent a pressure-rupturable seal, a pre-filled reservoir with a releasable barrier wall in the form of a releasable or frangible strip, or the use of a pull tab to release liquid from a pre-filled reservoir.

Neither the description nor the claims describe clearly how these systems are to be executed, however, in the case of the pressure activated the activation process relies upon the hydraulic pressure generated by compression of the blister (204) to partially de-laminate a multi-laminar label structure (201,202), thereby inflating and filling a second, newly created reservoir (in the circled region) with liquid (205).

A further embodiment suggests creating the necessary weakness in lamination by incorporation of a foil layer interposed between the laminar plates IJS7232253 (ISBITSKY) describes a time indicator label with a very similar activation mechanism to that described above, best embodied in Figures 5A and 5B of US7232253, showing the inactive and activated states respectively. A new reservoir (68) is created via hydraulically initiated delamination of a laminate formed from a PVC layer (51) and a 'plastic layer' (60) in an area (67) weakened by printing prior to lamination. As pressure is applied to dished portion (52) liquid from reservoir (54) is forced through inlet (64) and the hydraulic pressure thus generates causes the new reservoir (68) to fill and expand. The description states that the dished portion (52) remains in its depressed state, but there is no elucidation as to how this is ensured.

Both of these disclosures suffer from the same drawbacks, the label construction is complex and unwieldy, requiring a sizeable amount of material making them both expensive and bulky; two factors of vital importance in a mass application label US2005/0068760 A (FORMAGLOW LTD) describes a chemiluminescent device, wherein the application of pressure is used to mpture micro-capsules containing either one or both of the components required for chemiluminscence, the microcapsules are enclosed between relatively thick plastic layers as the 'device' is aimed at plastic drinks bottles and the like.

W02007/121519 A (BATE'S' et al.) describes a chemiluminescent label, again suitable for drinks bottle and suchlike The lab& (Figure 2 of W02007/121519 A) comprises two separate chambers (23,24), each containing one of the components necessary to produce a chemiluminescent reaction, both chambers being adjacent a third, mixing chamber (20), and separated therefrom by separate and independently frangible walls (26).

The label is activated through application of sufficient pressure to rupture the frangible walls (26), although no detail is offered as to how the walls are made to be frangible, nor how much pressure is required. Again, due to the nature of the material used this would not be suitable for a large proportion of products or supply chain settings.

The prior art systems discussed above all suffer from problems with both amounts of material used and complexity of construction, requiring multiple cutting, laminating and filling operations, which necessarily reduce the speed at which the labels can be manufactured and substantially increases the costs, whilst also increasing the thickness of any label thus produced Because each of the multiple layers in the prior art systems are sequentially laminated together, each individual layer must be of sufficient thickness to provide enough tensile strength across the web to allow for high speed, reel to reel winding during the manufacturing process, and those layers with cut out portions must be thicker still due to the reductions in tensile strength inherent in removing portions of the web. The thicker the labels thus produced, the less flexible they are likely to be, thereby reducing the number of potential applications. Such limitations would occur in applying such labels to any surfaces with tight radii, such as vaccine bottles, eye drops, mascara etc...

It is an object of the present invention to provide a time-temperature integrating packaging system that addresses at least some of the problems associated with the prior art devices, whilst being capable of rapid and cheap manufacture

Summary of Invention

The present invention is directed towards a printed time-temperature integrating packaging system suitable for food, cosmetics, pharmaceutical and other products which need to be stored and/or transported at controlled temperatures in order to maintain their freshness/efficacy, the entire system may be formed in a continuous, reel to reel, in-line printing process For the purposes of this application, the term printing can include traditional printing technologies, such as offset printing (where a reverse image is printed onto an intermediate substrate (e.g. a secondary roller) and subsequently transferred onto a base substrate).

Recently, digital printing and specifically inkjet technology has moved rapidly forwards, particularly in the area of nozzle resolution and droplet volumes.

Natural (manufactured mechanical) nozzle resolution is now commonly in the realm of 400 nozzles per inch, and interlacing concurrent jetting heads or sabring (angling) of individual jetting heads allows for much higher/tighter droplet concentration. The application or combination of these strategies allows for greater inherent image fidelity and application precision, high precision printing up to 1,200 dots per inch [dpi] can be realised, producing super high definition, high quality imagery.

The total range of droplet size has been progressively stretched, high precision printing up to 1,200 dots per inch [dpi] as discussed above, require much smaller droplet volumes so as not to blur the imagery. Technological advances have reduced droplet sizes (circa 2 picolitres in volume) to facilitate this need. At the other end of the spectrum, larger droplet sizes are now achievable (circa 120 picolitres) which in conjunction high firing frequency rates, circa. >20,000 Hz allow for ultra-high media film thicknesses to be achieved, and also the potential for inkjet printing techniques to be used as small scale, precision liquid filling processes. Applications such as relief Braille printing now become a reality, along with the ability for of continuous process 3D printing, (textures, features, steps, reliefs, etc), an ability and feature which this technological application espouses.

It was determined that emerging improvements in Inkjet technology could enable the production of a 3D printed construction of limited but significant vertical dimensions onto a continuously moving web of substrate material, that vertical component being sufficient to allow for microfluidic processes to be accommodated and subsequently function as an active device, A further advantage of using an inline printing process for label production is that it enables rapid redesign and/or modification of label appearance and structure without the need for retooling existing machinery and the inherent downtime that this would require. Similarly, multiple designs and/or prototypes can be produced both cost effectively and simultaneously on the same base material to allow for direct and contemporaneous comparison A further advantage of using an inline inkjet printing process is that the entire label production can be performed at high speed as a single reel to reel continuous process, thereby enabling mass production at greatly reduced costs.

The present invention provides a time-temperature integrating packaging system, characterised in that both the reagents and the internal structure of the system are printed directly onto a base substrate, said substrate preferably being one of a label base layer, an existing packaging material or even directly onto a product.

The present invention also provides a method of manufacturing a time-temperature integrating packaging system, comprising printing both the reagents and the internal structure of the system directly onto a base substrate First aspect of the Invention In a first aspect of the present invention there is provided a time-temperature integrating packaging system comprising a base layer onto which has been printed at least an initiator source material and a diffusion medium.

It will be appreciated that the base layer may be a dedicated layer of new material, e.g. a self-adhesive layer that may be applied to product packaging, or it may be part of another product, e.g. the existing packaging of a product.

In embodiments of the first aspect of the invention, the initiator source material is deformable. In embodiments of the first aspect of the invention, the initiator source material is both flexible and compressible. In some embodiments, the initiator source material may be considered to be resilient.

In embodiments of the first aspect of the invention, said initiator source material, or part thereof, is configured to diffuse through said diffusion medium upon activation, resulting in a visible change to the system (e.g. a visible change to the diffusion medium or the initiator source material). This may allowing an observer to track the time-temperature history of a package.

In embodiments of the first aspect of the present Invention the initiator source material is comprised of an anhydrous gel material The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol, and/or glycerol.

In embodiments of the first aspect of the present invention the diffusion material is comprised of an anhydrous gel material. The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In preferred embodiments, the initiator source material and the diffusion medium are both comprised of anhydrous gel materials. In such embodiments, the initiator source material and the diffusion medium may be comprised of the same anhydrous gel material, or may be comprised of different anhydrous gel materials. The anhydrous gel materials may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700 PEGDA 1000 or a mixture thereof (hereafter PEGDA). As described in the present application, the mixture may comprise two or more of the PEGDA gel materials described herein. The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol, and/or glycerol.

In embodiments, the initiator source material and the diffusion medium share a common constituent comprising an anhydrous gel formed of polyethylene glycol diacrylate (PEGDA) with an average molecular mass of 250, 400, 480, 700, 1000 or a mixture thereof (hereafter PEGDA), mixed with propylene carbonate (PC), propylene glycol (PG) and glycerol (replacing the water that one would use in preparing a standard PEGDA hydrogel) Gels of this formulation were found to be particularly effective.

A further advantage of using anhydrous media is that the freezing point is not closely tied to the freezing point of water, thereby enabling the use of gels that become solid at another predetermined temperature, providing accurate cold chain distribution tracking of a wider range of goods/products Anhydrous gels have also been observed to avoid issues with the moisture-vapour transmission rate, moisture loss through evaporation and crystallisation due to freezing, that has been observed with aqueous content In alternative embodiments, the initiator source material is comprised of a hydrogel material. In other embodiments the diffusion material is comprised of a hydrogel material. In further embodiments, initiator source material and the diffusion medium are both comprised of hydrogel materials.

In embodiments of the first aspect of the invention, the initiator source material comprises an acid, preferably formic acid.

In embodiments of the first aspect of the invention, the diffusion medium comprises an acid sensitive indicator, preferably one or more of methyl red, bromothymol blue, neutral red, rosolic acid, phenol red, naphthyl red and propyl red, most preferably methyl red It will be appreciated that the acid sensitive indicator responds to changes in pH levels (i.e. due to a change in acidity). The acid sensitive indicator may, for example, be a pH responsive pigment In alternative embodiments of the first aspect of the invention, the initiator source material comprises a base (e.g. an alkali). In such embodiments of the first aspect of the invention, the diffusion medium may comprise a base (e.g. an alkali) sensitive indicator.

In embodiments of the first aspect of the invention, the diffusion medium further comprises one or more buffering materials. The buffering material(s) preferably comprise salt(s), for example, sodium carbonate or sodium bicarbonate. Most preferably the salt(s) are a mixture of sodium carbonate arid sodium bicarbonate.

The addition of buffer salts was found to not only improve the curing characteristics of the gel, with a firmer/stiffer gel being produced; but also reduced the instance of self-activation of labels constructed therewith and generated a cleaner diffusion front subsequent to activation. The addition of a mixture of sodium carbonate and sodium bicarbonate to the glycerol prior to its inclusion in the gel mixture, was found to be specifically beneficial.

In embodiments of the first aspect of the invention, the initiator source material is cured subsequent to being printed onto the base layer. In other embodiments, the diffusion material is cured subsequent to being printed onto the base layer. In further embodiments, both the initiator source material and the diffusion medium are cured subsequent to the media (the initiator source material and the diffusion medium) being printed onto the base layer. In such embodiments, at least the initiator source material may be deformable subsequent to said curing. In such embodiments of the first aspect of the invention, at least the initiator source material may be both flexible and compressible. In such embodiments, at least the initiator source material may be resilient.

In embodiments, the media may be encapsulated onto said base layer by a further printed material or a conformal coating, which is itself may be cured subsequent to printing; said conformal coating preferably comprising an anhydrous gel. Said anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700 PEGDA 1000 or a mixture thereof (hereafter PEGDA). The anhydrous gel may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol Preferably the anhydrous gel of the conformal coating comprises PEGDA, propylene carbonate, propylene glycol and glycerol; even more preferably it further comprises one or more buffering salts, said buffering salts preferably comprising a mixture of sodium carbonate and sodium bicarbonate In embodiments of the first aspect of the invention, a curable monomer mixture is printed onto said base layer and cured, forming one or more compartments, which may be semi-rigid, flexible, on said base layer, into which said initiator source material and said diffusion medium are subsequently printed (and optionally cured).

In such embodiments, one or more semi-rigid, flexible compartments may comprise at least an initiator chamber, a mixing/diffusion chamber adjacent said initiator chamber, and a diffusion strip, contiguous with said mixing chamber.

In embodiments of the first aspect of the invention, a further flexible web is subsequently laminated over the base layer, thereby sealing in said various printed components (e g, the initiator source material and the diffusion material), said flexible web may further carry visible printed media displaying one or both of decorative or functional imagery.

In embodiments of the first aspect of the invention, the system further comprises an activation indicator, said activation indicator providing a visual sign that the system has been activated.

In embodiments of the first aspect of the invention, base layer is a label, preferably a self-adhesive label.

In embodiments of the first aspect of the invention, said base layer comprises a packaging element or wrapper; said additional elements being printed directly thereon In embodiments of the first aspect of the invention, said printed elements are initially printed onto a transfer roller, blanket, or pad prior to deposition onto said base layer.

In embodiments of the first aspect of the invention, said initiator source material and said diffusion medium are printed in intimate contact with one another, such that the time-temperature integrating system is activated at the point of manufacture.

In alternative embodiments of the first aspect of the invention, the initiator source material and the diffusion medium are printed physically separate from one another. In such embodiments, it may require the application of pressure on the initiator source to physically connect said initiator source material to said diffusion medium such that one or more components of said initiator source material is able to diffuse into/through said diffusion medium thereby activating said time-temperature integrating system.

In embodiments of the first aspect of the invention, the diffusion medium comprises a choke point (e.g. a neck or narrowing). The choke point may function to regulate the speed of the diffusion of the initiator source material through the diffusion medium. This may allow control of when the visible change observed by the end user. It may also help improve the consistency of the visible change.

In embodiments of the first aspect of the invention, an edge of the initiator source material located proximal to the diffusion medium comprises a feathering In such embodiments, an edge of the diffusion medium located proximal the initiator source may comprise a complementary feathering.

In embodiments of the first aspect of the invention, the initiator source material is elongated and tapered to a point The point being located proximal to the diffusion medium.

In embodiments of the first aspect of the invention, the initiator source material comprises internal directional baffles In embodiments of the first aspect of the invention, the system further comprises a mixing zone. The mixing zone may be part of the diffusion material and located between the initiator source material and the rest of the diffusion material. The system may also further comprise an angled baffle at the confluence of mixing zone and diffusion medium.

In embodiments of the first aspect of the invention, the label design (system) is adapted to be activated via the application of pressure from a roller. The roller may be an integral part of a label application machine, or may be a manually operated device.

In embodiments of the first aspect of the invention, the label design (system) is adapted to be activated via controlled directional displacement or compression, said compression being applied either by a reciprocating tool on a label application machine, a manually activated device or manual activation by an end-user, In embodiments of the first aspect of the invention, said initiator source material is deposited in such a manner as to be tapered towards said diffusion medium such that a subsequent conformal coating layer deposited atop thereof extending beyond the edge of said initiator source material, generates a hydraulic wedge effect when pressure is applied to said initiator source material.

In embodiments of the first aspect of the invention, said base layer has been modified in the region beyond the initiator source material, such that said conformal coating deposited thereon has a lower level of adhesion that with untreated base layer material, said modification optionally being in the form of a corona treatment.

Second aspect In a second aspect of the present invention there is provided a time-temperature integrating packaging system comprising a base layer comprising an initiator source material and a diffusion medium.

In embodiments of the second aspect of the present invention the initiator source material may be a printed initiator source material. The diffusion medium may be a printed diffusion medium. In such embodiments the initiator source material and/or the diffusion medium may be a printed and cured material, i.e. they may have been printed and cured.

In embodiments of the first aspect of the invention, the initiator source material is deformable In embodiments of the first aspect of the invention, the initiator source material is both flexible and compressible. In some embodiments, the initiator source material may be considered to be resilient.

In embodiments of the second aspect of the invention, said initiator source material is configured to diffuse through said diffusion medium upon activation, resulting in a visible change to the system (e.g. a visible change to the diffusion medium or the initiator source material). This may allowing an observer to track the time-temperature history of a package.

In embodiments of the second aspect of the present invention the initiator source material is comprised of an anhydrous gel material. The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In embodiments of the second aspect of the present invention the diffusion material is comprised of an anhydrous gel material The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In preferred embodiments, the initiator source material and the diffusion medium are both comprised of anhydrous gel materials. In such embodiments, the initiator source material and the diffusion medium may be comprised of the same anhydrous gel material, or may be comprised of different anhydrous gel materials. The anhydrous gel materials may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700 PEGDA 1000 or a mixture thereof (hereafter PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In alternative embodiments, the initiator source material is comprised of a hydrogel material. In other embodiments the diffusion material is comprised of a hydrogel material. In further embodiments, initiator source material and the diffusion medium are both comprised of hydrogel materials.

In embodiments of the second aspect of the invention, the initiator source material comprises an acid, preferably formic acid.

In embodiments of the second aspect of the invention, the diffusion medium comprises an acid sensitive indicator, preferably one or more of methyl red, bromothymol blue, neutral red, rosolic acid, phenol red, naphthyl red and propyl red; most preferably methyl red.

It will be appreciated that the acid sensitive indicator responds to changes in pH levels due to a change in acidity. The acid sensitive indicator may, for example, be a pH responsive pigment.

In embodiments of the second aspect of the invention, the initiator source material comprises a base (e.g. an alkali). In embodiments of the second aspect of the invention, the diffusion medium comprises a base (e.g. an alkali) sensitive indicator.

In embodiments of the second aspect of the invention, the diffusion medium further comprises one or more buffering materials. The buffering material(s) preferably comprise salt(s), for example, sodium carbonate or sodium bicarbonate. Most preferably the salt(s) are a mixture of sodium carbonate and sodium bicarbonate.

In embodiments of the second aspect of the invention, the initiator source material and the diffusion medium are encapsulated onto said base layer by a conformal coating.

In embodiments, the conformal material may be a printed material. In such embodiments the conformal coating may be a printed and cured material.

The conformal coating preferably comprising an anhydrous gel. Said anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700 PEGDA 1000 or a mixture thereof (hereafter PEGDA). The anhydrous gel may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol. Preferably, the anhydrous gel of the conformal coating comprises PEGDA, propylene carbonate, propylene glycol and glycerol. The conformal gel may also comprise one or more buffering salts, e.g. sodium carbonate and sodium bicarbonate, preferably a mixture of sodium carbonate and sodium bicarbonate.

In embodiments of the second aspect of the invention, the base layer comprises one or more semi-rigid compartments containing the initiator source material and the diffusion medium. Preferably, the initiator source material and the diffusion medium are in different compartments. in such embodiments, the compartments may comprise at least an initiator chamber, a mixing/diffusion chamber adjacent said initiator chamber, and a diffusion strip, contiguous with said mixing chamber.

In such embodiments the compartments may be formed by a polymeric material located on the base layer.

In embodiments of the second aspect of the invention, the system further comprises a flexible web laminated over the base layer, which seals the initiator source material and the diffusion medium. The flexible web may further comprise visible printed media displaying one or both of decorative or functional imagery.

In embodiments of the second aspect of the invention, the system further comprises an activation indicator, said activation indicator providing a visual sign that the system has been activated. The activation indicator may be located on the base layer.

In embodiments of the second aspect of the invention, base layer is a label, preferably a self-adhesive label.

In embodiments of the second aspect of the invention, said base layer comprises a packaging element or wrapper.

In embodiments of the second aspect of the invention, said initiator source material and said diffusion medium are in contact with one another, such that the time-temperature integrating system is activated at the point of manufacture.

In alternative embodiments of the second aspect of the invention, the initiator source material and the diffusion medium are physically separate from one another. In such embodiments the system may be configured such that the application of pressure on the initiator source allows a physically connect of the initiator source material to said diffusion medium such that one or more components of said initiator source material is able to diffuse into/through said diffusion medium thereby activating said time-temperature integrating system.

In embodiments of the second aspect of the invention, the diffusion medium comprises a choke point (e.g. a neck or narrowing). The choke point functions to regulate the speed of the diffusion of the initiator source material through the diffusion medium. This may allow control of when the visible change observed by the end user. It may also help improve the consistency of the visible change.

In embodiments of the second aspect of the invention, an edge of the initiator source material located proximal to the diffusion medium comprises a feathering. In such embodiments, an edge of the diffusion medium located proximal the initiator source may comprise a complementary feathering.

In embodiments of the second aspect of the invention, the initiator source material is elongated and tapered to a point. The point being located proximal to the diffusion medium In embodiments of the second aspect of the invention, the initiator source material comprises internal directional baffles.

In embodiments of the second aspect of the invention, the system further comprises a mixing zone. The mixing zone may be part of the diffusion material and located between the initiator source material and the rest of the diffusion material. The system may also further comprise an angled baffle at the confluence of mixing zone and diffusion medium In embodiments of the second aspect of the invention, the label design (system) is adapted to be activated via the application of pressure from a roller. The roller may be an integral part of a label application machine, or may be a manually operated device.

In embodiments of the second aspect of the invention, the label design (system) is adapted to be activated via controlled directional displacement or compression, said compression being applied either by a reciprocating tool on a label application machine, a manually activated device or manual activation by an end-user.

In embodiments of the second aspect of the invention, said initiator source material is deposited in such a manner as to be tapered towards said diffusion medium such that a subsequent conformal coating layer deposited atop thereof, extending beyond the edge of said initiator source material, generates a hydraulic wedge effect when pressure is applied to said initiator source material.

In embodiments of the second aspect of the invention, said base layer has been modified in the region beyond the initiator source material, such that said conformal coating deposited thereon has a lower level of adhesion that with untreated base layer material, said modification optionally being in the form of a corona treatment.

Third Aspect In a third aspect of the invention there is provided a method for constructing a time-temperature integrating system, comprising printing and curing at least an initiator source material, and a diffusion medium onto a base layer, characterised in that at least said initiator source material is deformable subsequent to said curing By a deformable initiator source material, it will be understood that the initiator source material will move within the system under the application of force. In some embodiments, it may be considered to be both flexible and compressible. In some embodiments, it may be considered to be resilient.

It will be appreciated that the curing step may result in a hardening of the initiator source material but it does not necessarily produce a rigid initiator source material. Curing may for example involve forming a cross-linked polymer matrix.

In embodiments of the third aspect of the present invention the initiator source material is comprised of an anhydrous gel material. The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In embodiments of the third aspect of the present invention the diffusion material is comprised of an anhydrous gel material. The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In embodiments of the third aspect of the invention, the initiator source material comprises an acid, preferably formic acid In embodiments of the third aspect of the invention, the diffusion medium comprises an acid sensitive indicator, preferably one or more of methyl red, bromothymol blue, neutral red, rosolic acid, phenol red, naphthyl red and propyl red; most preferably methyl red In embodiments of the third aspect of the invention, the initiator source material comprises a base (e.g. an alkali). In embodiments of the third aspect of the invention, the diffusion medium comprises a base (e.g. an alkali) sensitive indicator.

In embodiments of the third aspect of the invention, the diffusion medium further comprises one or more buffering materials. The buffering material(s) preferably comprise salt(s), for example, sodium carbonate or sodium bicarbonate. Most preferably the salt(s) are a mixture of sodium carbonate and sodium bicarbonate.

In some embodiments of the third aspect of the invention where the diffusion medium is an anhydrous gel material further comprising propylene carbonate, propylene glycol and glycerol. The one or more buffering materials may be added to the anhydrous gel material mixture or pre-dissolved in the glycerol In embodiments of the third aspect of the invention, the method further comprises providing (e.g. printing and curing) a conformal coating layer over the top of said initiator source material and a diffusion medium (the media).

The conformal coating preferably comprises an anhydrous gel. Said anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700 PEGDA 1000 or a mixture thereof (hereafter PEGDA). The anhydrous gel may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol Preferably the anhydrous gel of the conformal coating comprises PEGDA, propylene carbonate, propylene glycol and glycerol; even more preferably it further comprises one or more buffering salts, said buffering salts preferably comprising a mixture of sodium carbonate and sodium bicarbonate.

In embodiments of the third aspect of the invention, the method comprises forming one or more compartments semi-rigid compartments on said base layer prior to printing and curing the initiator source material and a diffusion medium onto said base layer. The compartments may provide a target into which said initiator source material and a diffusion medium are subsequently printed.

In such embodiments of the third aspect of the invention, the method may comprise printing a monomer mixture onto said base layer, then curing said monomer mixture to form one or more semi-rigid, flexible compartments on said base layer; said one or more compartments providing a target into which said initiator source material and a diffusion medium (media) are subsequently printed and cured.

In such embodiments, forming one or more semi-rigid, flexible compartments may comprise forming at least an initiator chamber, a mixing/diffusion chamber adjacent said initiator chamber, and a diffusion strip, contiguous with said mixing chamber.

In embodiments of the third aspect of the invention, the method further comprises laminating a further flexible web over the base layer, thereby sealing in the various printed components (initiator source material and a diffusion medium), said flexible web may further carry visible printed media displaying one or both of decorative or functional imagery.

In embodiments of the third aspect of the invention, the system further comprises providing (e.g., printing) an activation indicator, said activation indicator providing a visual sign that the system has been activated.

In embodiments of the third aspect of the invention, said printed elements are initially printed onto a transfer roller, blanket, or pad prior to deposition onto said base layer.

In embodiments of the third aspect of the invention, said initiator source material and said diffusion medium are printed in intimate contact with one another, such that the time-temperature integrating system is activated at the point of manufacture.

In alternative embodiments of the third aspect of the invention, the initiator source material and the diffusion medium are printed physically separate from one another. In such embodiments, it may require the application of pressure on the initiator source to physically connect said initiator source material to said diffusion medium such that one or more components of said initiator source material is able to diffuse into/through said diffusion medium thereby activating said time-temperature integrating system. In embodiments of the third aspect of the invention, subsequent to printing and curing of said initiator source material, a first pass of conformal coating material is printed over the top of said initiator source material, extending beyond the edge thereof, such that a tapered edge is formed proximal the subsequently printed diffusion medium In embodiments of the third aspect of the invention, the method further comprises activating the system. In such embodiments, the activation may be via the application of pressure to the system (e.g. the initiator source) from a roller. The roller surface may be of a hard and incompressible material, such as stainless steel This may give a knife edge compression line. The roller surface may also be covered with an elastomeric material in order to increase the process direction size of the compression footprint.

In embodiments of the third aspect of the invention, the printing of the initiator source material and the diffusion medium onto a base layer is via a continuous, reel to reel, in-line printing process In further embodiments, the entire time-temperature integrating packaging system may be formed in a continuous, reel to reel, in-line printing process Fourth Aspect In a fourth aspect of the invention there is provided a method for constructing a time-temperature integrating system, comprising printing at least an initiator source material, and a diffusion medium onto a base layer.

In embodiments of the third aspect of the present invention, the method further comprises curing the initiator source material and/or the diffusion material after printing the initiator source material and/or the diffusion material onto the base layer.

The curing of the initiator source material may result in an initiator source material that remains deformable. By a deformable initiator source material, it will be understood that the initiator source material will move within the system under the application of force. In some embodiments, it may be considered to be flexible and compressible. In some embodiments, it may be considered to be resilient. The curing may involve forming a cross-linked polymer matrix.

In embodiments of the fourth aspect of the present invention the initiator source material is comprised of an anhydrous gel material. The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In embodiments of the fourth aspect of the present invention the diffusion material is comprised of an anhydrous gel material The anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700, PEGDA 1000, or a mixture thereof (hereafter named PEGDA). The anhydrous gel material may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol.

In embodiments of the fourth aspect of the invention, the initiator source material comprises an acid, preferably formic acid In embodiments of the fourth aspect of the invention, the diffusion medium comprises an acid sensitive indicator, preferably one or more of methyl red, bromothymol blue, neutral red, rosolic acid, phenol red, naphthyl red and propyl red, most preferably methyl red.

In embodiments of the fourth aspect of the invention, the initiator source material comprises a base (e.g. an alkali). In embodiments of the fourth aspect of the invention, the diffusion medium comprises a base (e.g. an alkali) sensitive indicator.

In embodiments of the four aspect of the invention, the diffusion medium further comprises one or more buffering materials. In embodiments of the four aspect of the invention, the method may further comprise mixing one or more buffering materials with the diffusion material prior to printing. The buffering material(s) preferably comprise salt(s), for example, sodium carbonate or sodium bicarbonate. Most preferably the salt(s) are a mixture of sodium carbonate and sodium bicarbonate. In some embodiments of the fourth aspect of the invention where the diffusion medium is an anhydrous gel material further comprising at least glycerol, the one or more buffering materials may be added to the anhydrous gel material mixture or may be pre-dissolved in the glycerol.

In embodiments of the fourth aspect of the invention, the method further comprises printing a conformal coating layer over the top of said initiator source material and a diffitsion medium (the media). In further embodiments of the fourth aspect of the invention, the method further comprises curing the conformal coating layer.

The conformal coating preferably comprises an anhydrous gel. Said anhydrous gel may be selected from PEGDA 250, PEGDA 400, PEGDA 480, PEGDA 700 PEGDA 1000 or a mixture thereof (hereafter PEGDA). The anhydrous gel may further comprise (or may be gelled with) propylene carbonate, propylene glycol and/or glycerol Preferably the anhydrous gel of the conformal coating comprises PEGDA, propylene carbonate, propylene glycol and glycerol, even more preferably it further comprises one or more buffering salts, said buffering salts preferably comprising a mixture of sodium carbonate and sodium bicarbonate In embodiments of the fourth aspect of the invention, the method comprises forming one or more compartments semi-rigid compartments on said base layer prior to printing the initiator source material and a diffusion medium onto said base layer. The compartments may provide a target into which said initiator source material and a diffusion medium are subsequently printed. The forming of one or more semi-rigid compartments on said base layer may involve printing a monomer mixture onto said base layer and curing said monomer mixture.

In embodiments of the fourth aspect of the invention, the method further comprises laminating a further flexible web over the base layer, thereby sealing in the various printed components (initiator source material and a diffusion medium), said flexible web may further carry visible printed media displaying one or both of decorative or functional imagery.

In embodiments of the fourth aspect of the invention, the system further comprises applying an activation indicator, said activation indicator providing a visual sign that the system has been activated Applying an activation indicator may involve printing an activation indicator.

In embodiments of the fourth aspect of the invention, said printed elements are initially printed onto a transfer roller, blanket, or pad prior to deposition onto said base layer.

In embodiments of the fourth aspect of the invention, said initiator source material and said diffusion medium are printed in intimate contact with one another, such that the time-temperature integrating system is activated at the point of manufacture.

In alternative embodiments of the fourth aspect of the invention, the initiator source material and the diffusion medium are printed physically separate from one another. In such embodiments, it may require the application of pressure on the initiator source to physically connect said initiator source material to said diffusion medium such that one or more components of said initiator source material is able to diffuse into/through said diffusion medium thereby activating said time-temperature integrating system. In embodiments of the third aspect of the invention, at, subsequent to printing and curing of said initiator source material, a first pass of conformal coating material is printed over the top of said initiator source material, extending beyond the edge thereof, such that a tapered edge is formed proximal the subsequently printed diffusion medium.

In embodiments of the third aspect of the invention, the method further comprises activating the system. In such embodiments, the activation may be via the application of pressure to the system (e.g. the imitator source) from a roller. Said roller surface may be of a hard and incompressible material, such as stainless steel. This may give a knife edge compression line. The roller surface may also be covered with an elastomeric material in order to increase the process direction size of the compression footprint.

In embodiments of the fourth aspect of the invention, the printing of the initiator source material and the diffusion medium onto a base layer is via a continuous, reel to reel, in-line printing process. In further embodiments the entire time-temperature integrating packaging system may be formed in a continuous, reel to reel, in-line printing process (e.g., all of the components applied to the base layer are applied via a continuous, reel to reel, in-line printing process).

Fifth aspect Use of the time-temperature integrating packaging system according to the first or second aspects of the invention It will be appreciated that, where appropriate, any features described in relation to one aspect of the invention are also intended to be disclosed in relation to the other aspects.

The invention also comprises a printed, time-temperature integrating packaging system and a method for the manufacture thereof, substantially as hereinbefore described with reference to the accompanying claims, drawings and description.

Brief description of figures

Figure t shows an embodiment of the time-temperature integrating packaging system according to the present invention Figure 2 shows an alternative embodiment of the time-temperature integrating packaging system according to the present invention Figure 3 shows an alternative embodiment of the time-temperature integrating packaging system according to the present invention Figure 4 shows an alternative embodiment of the time-temperature integrating packaging system according to the present invention Figure 5 shows an alternative embodiment of the time-temperature integrating packaging system according to the present invention Figure 6 shows an alternative embodiment of the time-temperature integrating packaging system according to the present invention Figure 7 shows illustrative examples of elongated initiator sources with directional baffles Figure 8 shows an embodiment of the time-temperature integrating packaging system according to the present invention

Detailed Description

Initially, efforts were directed at producing structures similar to those that could be achieved via standard die cutting and lamination techniques, albeit with considerably thinner internal layers allowing increased flexibility.

In a first example and with reference to Figure 1, a curable monomer mix (501) was printed onto a moving web, then passed under a curing station (UV source) to form semi-rigid, yet flexible compartments on said web, said compartments comprising an initiator chamber (502), a mixing/diffusion chamber (503) adjacent said initiator chamber, and a diffusion strip (504), contiguous with said mixing chamber; appropriate, gellable materials were then printed into their respective chambers and cured by passing under another curing station (UV source) with a final, upper web then laminated over the whole.

The initial curable monomer is a structural media laydown creating cavities in which active media can reside, in other words, a UV curable Reservoir Body Media [RBM]. One of the advantages of this process is that whilst the reservoirs or receptor shapes can be created by depositing a high vertical dimension encasement wall (somewhat like a canal lock), the base of the reservoirs or receptor shapes can also receive a thin layer of the same material through image dithering (the process of volume reduction through artwork processing), thus ensuring that the surface of the base material is 'primed' or made consistent to allow for the receipt of subsequently jetted active media, providing a regular and controllable process, irrespective of the grade, treatment, or source of the base substrate material.

In a second example, with reference to Figure 2, the initial stage of printing and curing the compartments was completely omitted, with the active materials being laid down onto virgin web and the upper web was augmented with a printed and cured conformal coating of a flexible, gellable material, thereby creating a hermetically sealed, airless system Thus an initiator source (602) was printed onto a moving web (601) and cured by passing under a IN source, adjacent said initiator source (602) was printed and cured a diffusion medium (603), with a gellable conformal coating (604) then being printed over the top and cured, with a final flexible layer (carrying decorative/functional artwork variations) being laminated over said cured conformal coating, under which any microscopic air gaps no longer have any discernible impact on the functionality of the system.

In alternative embodiments thereof, the decoration/artwork may be printed directly onto the surface of the gellable, conformal coating (subsequent to curing); onto the over-laminate film prior to lamination (either by inkjet or other printing processes), or printed onto a clear,overlaminate film subsequent to the lamination process.

The resulting label was an improvement over that shown in Figure 1, with the initiator source in Figure 2 was both easier to depress and provided a higher level of haptic feedback that example shown in figure 1. Various spacings between the initiator source and diffusion medium were trialled with there being a balance to be struck between ease of activation (the smaller the gap, the easier the label was activated) and durability/risk of self-activation (the larger the gap, the greater shelf life and reduced likelihood of self-activation/failure) There was also some variability with regards to the amount of initiator material that breached the seal formed by the conformal coating between initiator source and diffusion medium; said variability increasing as the distance between the initiator source and diffusion medium was increased.

Thus, and with reference to Figure 3, a 'feathering' was introduced to one edge of the initiator source (the edge proximal the diffusion medium), with complimentary feathering on the edge of the diffusion medium proximal the initiator source, with samples then being produced with the respective feathered areas either separated (Fig. 7A) or intertwined (Fig. 7B).

An initiator source (702) was printed onto a moving web and cured by passing under a UV source, adjacent said initiator source (702) was printed and cured a diffusion medium (703), with a gellable conformal coating then being printed over the top and cured. The side of the initiator source proximal the diffusion medium was formed with a plurality of protrusions (705), with the edge of the diffusion medium proximal the initiator source being formed with a plurality of protrusions (706) complimentary to those formed on the initiator source, said diffusion medium was also formed with an expanded, mixing zone (707) adjacent the initiator source.

Various shapes and sizes of protrusion ranging from intertwined, comb like structures to single, arrowhead structures were tried in attempts to both improve ease and reduce variability of activation.

Perhaps counterintuitively, labels where the feathering/protrusions were intertwined (as exemplified in Figure 3B) proved more difficult to activate than those where the feathered regions were physically separated (as exemplified in Figure 3A), whilst increasing the number of protrusions improved the performance of the activation mechanism.

In order to reduce instances of self-activation, and to improve the directionality (and therefore consistency) of activation a number of additional 'structures' may be introduced to both the initiator source and the mixing zone/diffusion medium.

With reference to Figure 4, the initiator source (802) was elongated, and tapered to a point towards the end proximal the mixing zone (807), furthermore, internal, directional baffles (808) were introduced to the initiator source. The mixing zone (807) was further differentiated from the diffusion medium (803) as a whole by the introduction of an angled baffle (810) at the confluence of mixing zone and diffusion medium and a dithered portion (809) introduced proximal the initiator source; de facto creating a separate target zone (811) near to the initiator source.

With further reference to Figures 4B and 4C, the size and shape of both the dithered portion and the target zone were varied.

It should be made clear that when speaking of introducing structures, such as the directional baffles (808) or the angled baffle (810), these are not additional elements needing to be added to the device separately, rather they are created by adjusting the shape being printed onto the moving, base web. Similarly, the dithered region (809) is simply created by printing a region of discrete dots/pixels rather than a solid printed area; hence it can be seen that these developments were not previously possible, and are unattainable with the traditional label manufacturing technologies.

The directional baffles (808) produced a far more unidirectional movement of initiator material upon compression, and also delivered a more pronounced level of haptic feedback, whilst the dithered region (809) and angled baffle (810) led to a large reduction in self-activation.

In a further embodiment (Figure 5) the mixing zone (907) is curved in order to reduce internal turbulence upon activation, and the angled baffle is replaced with an arcuate baffle (910), again to reduce turbulence and improve the uniformity of activation, whilst allowing the placement of an "activation witness", a transparent window to visually alert the user (generally by means of a colour change) to the fact that the label has been successfully activated.

In a further embodiment (Figure 6), the initiator source (1002) is considerably more elongate, and optionally tapered; with the target zone (1011) formed to present an obtuse angled target proximal one end of an almost semi-circular mixing zone (1007), allowing a larger volume of initiator whilst encouraging more efficient evacuation of the initiator chamber, especially when combined with the use of a roller to apply the activating pressure..

It will be appreciated by the skilled reader that any combinations of the above features can be readily and easily combined, simply by adjusting the patterns being printed onto the base web, such that an elongated initiator source can readily be printed down with directional baffles, and both the number, length and width of the directional baffles can be modified to optimise performance based on the physical characteristics of the initiator source material. Several illustrative examples are shown in Figure 7.

Further optimisation can be conducted to reduce further issues such as, due to the materials being deposited in a liquid form prior to curing there is an inevitable 'relaxing' of said materials as a function of the materials surface tension and the surface energy of the substrate thereby reducing the definition of the shapes being printed, leading to inconsistencies in activation as the boundary between acid and indicator gels varies slightly from label to label. Furthermore, there is a limited directionality when the labels are activated, as downward pressure on the acid source tends to impel the acid gel equally in all directions rather than preferentially towards the indicator gel. This issue can be mitigated/eliminated in a variety of ways, whilst retaining a central depression mechanism: * The lower surface of the pneumatic, hydraulic or mechanical (e.g. cam controlled or lever operated) ram's foot pad can be formed from an elastomeric material; * The surface can be moulded to create a topology which would deliver differing levels of compression, direction, and compression timing (sequencing), wherein the peripheral area of the foot pad (outside the perimeter of the instigator reservoir) would be the first to be compressed and would increasingly be compressed as the central zone descends and is compressed, thus the initiator source material is not compressed centrally (radially) but directionally, with the high compression periphery repelling any tendency to rupture, whilst the instigator flow would be directed towards a weakened area of peripheral compression resulting in a controlled compression and evacuation, with no uncontrolled leakage.

Figure 8 shows two further embodiments of the present invention, both so closely related as not to merit discussion separately. The acid source 0201) is pi hued onto a base layer in an elongated form, tapering to a (rounded) point; adjacent the beginning of the diffusion/indicator gel (which is also printed onto the base layer) (1202) (the difference between the two embodiments is merely the shape of the beginning of the diffusion/indicator gel -one being a rounded point, comparable to the terminating end of the acid source; the other being a cup shape, to partially encompass the terminating end of the acid source) Upon compression of the acid source, the acid gel is impelled towards the 'beginning' of the indicator gel (leakage is prevented by a further, conformal coating covering both elements 1201 and 1202 -not shown in the figures), wherein mixing occurs both within the initial sector of the indicator gel but also in a dithered area (1204); said dithering impeding the movement of the acid gel only to such extent as to prevent the gel being impelled too far into the indicator gel and to provide a consistent initial level of mixing. Diffusion of the acid through the indicator gel then commences, with a visual indication of activation being revealed by the colour change in viewing window (1203) The conformal coating (not shown) may be otherwise printed with whatever designs are deemed necessary, or may alternatively be covered with a laminate (printed either before or after lamination).

It will be appreciated by a reader skilled in the art, that the provision of an activation indicator as described in relation to figure 8 could be equally applied to any of the preceding embodiments.

It was subsequently discovered that an alkaline mixtui e of' similar constitution (created by replacing the acid with an alkali whilst leaving the remainder of the formulation unchanged) does not suffer from any deleterious effects with regard to either forming a gel or the texture of a gel thereby formed. It will be readily apparent to one skilled in the art that there is little material difference between diffusing an alkali or an acid through the indicator gel, thus the acid source in any of the aforementioned labels can be replaced with an alkali source to deliver a similar effect; with the selection of an appropriate pH responsive pigment or pigments to deliver a colour change at the pH levels generated by the increase in alkalinity.

Whilst all of the abovementioned examples have been describing discrete labelling systems for subsequent application to a packaging material, it is recognised, that similar systems could also be printed directly onto a packaging element either prior to or subsequent said package element being filled. In some instances the packaging element will be formed of a material suitable for direct printing of the various label components as described above, whereas other packaging materials may require the application of an additional, impermeable layer in the region to be printed.

It has been recognised that there is a greater propensity for premature self-activation of labels, subsequent to rewinding of the carrier web, the closer to the inside of a reel they are This is due to the fact that the pressure is greater the closer one gets to the core of a wound reel of material This issue can be eliminated by the additional printing (and curing) of stripes of reservoir body material (or other suitable hard gelling polymer) along the edges and/or in between labels along the web; said stripes serving as load bearing bars to take the 'weight' of the outer layers of carrier web, thereby preventing compression of the acid source material and removing the aforementioned compression as a potential failure mode within the labels.

In a preferred embodiment, the initiator source material and the diffusion medium share a common base comprising an anhydrous gel formed of polyethylene glycol diacrylate (PEGDA) with an average molecular mass of 250, 400, 480, 700, 1000 or a mixture thereof (hereafter PEGDA), mixed with propylene carbonate (PC), propylene glycol (PG) and glycerol (replacing the water that one would use in preparing a standard PEGDA hydrogel).

Gels of this formulation formed effective gels, albeit there were some instances of self-activation of the labels; this shortcoming has subsequently been overcome by the addition of salts to the glycerol (in one or both of the diffusion medium and the conformal coating medium) to act as a buffer to the acid, specifically the addition of a mixture of sodium carbonate and sodium bicarbonate to the glycerol prior to its inclusion in the gel mixture The addition of these buffer salts not only improves the curing characteristics of the gel, with a firmer/stiffer gel being produced; but also reduced the instance of self-activation of labels constructed therewith and generated a cleaner diffusion front subsequent to activation.

Similar results were achieved with the addition of the buffer salts to the complete mixture, rather than pre-dissolving them in the glycerol; as such either method can be used dependent on other manufacturing restraints In some settings it is seen as beneficial to activate a label upon application to a degradable product such that the time-temperature profile is tracked from the moment the product is packaged up to the moment a product is frozen (or brought below a predetermined threshold temperature), have the progress of the label cease, or dramatically slow down, whilst the product is maintained below said threshold temperature and subsequently recommence time-temperature integration when the temperature rises above said threshold temperature. This process is achievable via the careful selection of the diffusion media such that gels are formed which effectively become solid at a pre-determined temperature, thereby reducing diffusion to zero until such time as the pseudo-solid is warm enough to behave again as a gel This highlights a further advantage of using anhydrous media, as the freezing point is not so closely tied to the freezing point of water, thereby enabling accurate cold chain distribution tracking of a wider range of goods/products.

Claims

Claims 1 A time-temperature integrating packaging system comprises a base layer onto which has been printed at least an initiator source material and a diffusion medium.
2 A system according to claim 1, further characterised in that said initiator source material and said diffusion medium are both comprised of anhydrous gel materials.
3 A system according to claim 2, further characterised in that said anhydrous gel materials comprise PEGDA gelled with propylene carbonate, propylene glycol and glycerol.
4 A system according to any preceding claim, further characterised in that said initiator source material comprises an acid.
A system according to claim 4, further characterised in that said acid is formic acid.
6 A system according to any preceding claim, further characterised in that said diffusion medium comprises an acid sensitive indicator.
7 A system according to claim 7, further characterised in that said indicator is methyl red.
8 A system according to any preceding claim, further characterised in that said diffusion medium comprises one or more salts.
9 A system according to claim 8, further characterised in that said one or more salts comprise a mixture of sodium carbonate and sodium bicarbonate.
10. A system according to any preceding claim, further characterised in that both the initiator source material and the diffusion medium are cured subsequent to being printed onto the base layer.
11. A system according to any preceding claim, further characterised in that said initiator source material and the diffusion medium are encapsulated onto said base layer by a further printed material/conformal coating, which is itself cured subsequent to printing.
12. A system according to claim 11, further characterised in that said conformal coating comprises an anhydrous gel material.
13. A system according to claim 12, further characterised in that said anhydrous gel material comprises PEGDA, propylene carbonate, propylene glycol and glycerol.
14. A system according to claim 13, further characterised in that said anhydrous gel material comprises one or more salts.
A system according to claim 14, further characterised in that said salts comprise a mixture of sodium carbonate and sodium bicarbonate.
16 A system according to any preceding claim, further characterised in that a curable monomer mixture is printed onto said base layer and cured, forming one or more semi-rigid, flexible compartments on said base layer, into which said initiator source material and said diffusion medium are subsequently printed and cured.
17 A system according to claim 16, further characterised in that said one or more semirigid, flexible compartments comprise at least an initiator chamber, a mixing/diffusion chamber adjacent said initiator chamber, and a diffusion strip, contiguous with said mixing chamber.
18 A system according to any preceding claim, further characterised in that a further flexible web is subsequently laminated over the base layer, thereby sealing in said various printed components, said flexible web may further carry visible printed media displaying one or both of decorative or functional imagery.
19 A system according to any preceding claim, fUrther comprises an activation indicator, said activation indicator providing a visual sign that the system has been activated.A system according to any preceding claim, further characterised in that said base layer is a label 21 A system according to claim 20, further characterised in that said label is a self-adhesive label.22 A system according to any of claims 1 to 19, further characterised in that said base layer comprises a packaging element or wrapper, at least said initiator source material and diffusion medium being printed directly thereon.23 A system according to any of claims 1 to 19, further characterised in that said printed elements (initiator source material and diffusion medium) are initially printed onto a transfer roller, blanket or pad prior to deposition onto said base layer.24 A system according to any preceding claim, further characterised in that said initiator source material and said diffusion medium are printed in intimate contact with one another, such that the time-temperature integrating system is activated at the point of manufacture.A system according to any of claims 1 to 23, further characterised in that the initiator source material and the diffusion medium are printed physically separate from one another, requiring the application of pressure on the initiator source to physically connect said initiator source material to said diffusion medium such that one or more components of said initiator source material is able to diffuse into/through said diffusion medium thereby activating said time-temperature integrating system.26 A system according to claim 25, wherein said system is adapted to be activated via the application of pressure from a roller, said roller being either an integral part of a label application machine or a manually operated device.27 A system according to claim 25, wherein said system is adapted to be activated via controlled directional displacement or compression, said compression being applied either by a reciprocating tool on a label application machine, a manually activated device or manual activation.28 A system according to any of claims 25 to 27, further characterised in that said initiator source material is deposited in such a manner as to be tapered towards said diffusion medium such that a subsequent conformal coating layer deposited atop thereof, extending beyond the edge of said initiator source material, generates a hydraulic wedge effect when pressure is applied to said initiator source material.29 A system according to claim 28, further characterised in that said base layer has been modified in the region beyond the initiator source material, such that said conformal coating deposited thereon has a lower level of adhesion that with untreated base layer material A method for constructing a time-temperature integrating system comprises printing and curing at least an initiator source material, and a diffusion medium onto a base layer, characterised in that at least said initiator source material is both flexible and compressible subsequent to said curing 31 A method according to claim 30, further characterised by printing and curing a conformal coating layer over the top of said initiator source material and diffusion medium 32 A method according to either of claims 30 or 31, further characterised by initially printing a monomer mixture onto said base layer, then curing said monomer mixture to form one or more semi-rigid, flexible compartments on said base laver; said one or more compartments providing a target into which said initiator source material and diffusion medium are subsequently printed and cured 33 A method according to any of claims 30 to 32, further characterised by laminating a further flexible web over the base layer, thereby sealing in said initiator source material and diffusion medium, said flexible web may further carry visible printed media displaying one or both of decorative or functional imagery.34 A method according to any of claims 30 to 33, further characterised in that, subsequent to printing and curing of said initiator source material, a first pass of conformal coating material is printed over the top of said initiator source material, extending beyond the edge thereof such that a tapered edge is formed proximal the subsequently printed diffusion medium.Use of a time-temperature integrating packaging system according to any one of claims 1 to 29.