This application is a National Stage Application of PCT Application No. PCT/GB2017/051716, filed Jun. 13, 2017, which claims priority to GB Application No. 1610250.1, filed Jun. 13, 2016. The disclosures of each of these documents is hereby incorporated by reference in its entirety.

FIELD OF INVENTION

The present invention relates to an indicator device, a method for preparing an indicator device, and products derived therefrom. In particular, the present invention relates to a laminated indicator device that is stable until it is activated. The products derived therefrom may include, for example, a multilayer adhesive sticker, which (once activated) can be used to detect or report the passage of time. The indicator device can also be used to show that packaging has been compromised and/or that a device has been compromised.

Perishable goods, and in particular drinks and foodstuffs, are often provided in some form of air-tight packaging. This packing can be applied in a modified atmosphere (known as modified atmosphere packaging (MAP)), which limits the presence of oxygen and which often involves purging the packaging with carbon dioxide. Alternatively, perishable goods may be packaged in normal atmospheric conditions.

Items that are packaged in air-tight packaging include: food, beverages, works of art, pharmaceuticals, medical diagnostic kits and sterilised packages. It is particularly desirable in the food industry to package goods such that their exposure to atmospheric conditions (and in particular, oxygen) after packaging is minimised. This can be used to effectively extend the shelf life of many perishable items.

BACKGROUND ART

Many different indicators and sensors for detecting the passage of time or for detecting when a package has been opened have been developed. Many of these depend on gas diffusion or similar related technologies. In particular, many of these are effective only over short time periods, are unstable before activation, and/or respond only to external agents such as oxygen or carbon dioxide.

Therefore, it is an object of the present invention to obviate or mitigate at least some of the disadvantages of the prior art.

A further object of the invention is to provide an indicator device that can be applied to perishable goods such as food or drink and/or associated packaging, pharmaceuticals or chemical reagents and/or associated packaging, or any item where it is desirable to detect that the item has been opened, or where it is desirable to detect for how long an item has been opened.

DISCLOSURE OF INVENTION

According to a first aspect of the invention there is provided an indicator device comprising:an indicator section comprising an indicator material that displays different visible properties in response to the presence or absence of an activating agent;an activator section comprising an activating agent that effects a change in the visible properties of the indicator material; anda barrier section comprising a barrier layer that is substantially impermeable to the activating agent, the barrier section being located between the indicator section and the activator section;wherein at least part of the substantially impermeable barrier layer is configurable to allow the activating agent and the indicator material to come into contact with each other, thereby effecting a change in visible properties of the indicator material.

The indicator device may be for indicating the passage of time.

The indicator device may be a laminate, or multi-layered, product.

The indicator material may be part of a composition. Depending on the nature of the indicator material, the indicator material, or indicator composition, may be activated by UV light, a reducing agent, an oxidising agent, carbon dioxide, a base, an alkali or an acid.

The indicator device may be configured to detect a change (increase or decrease) in the amount (i.e., the concentration) of any of the activating agent in the device, or a change in pH.

At least part of the substantially impermeable barrier layer may be removable and/or rupturable.

On removal of and/or rupture of at least part of the substantially impermeable barrier layer, the activating agent and the indicator material may come into contact with each other, thereby effecting a change in visible properties of the indicator material.

The indicator material may display different visible properties in response to the concentration of the activating agent.

The indicator device may further comprise a semi-permeable barrier layer configured to allow controlled movement of the activating agent to the indicator material.

The semi-permeable barrier layer may be located between the indicator section and the activator section.

The semi-permeable barrier layer may be located between the indicator material and the activating agent.

The semi-permeable barrier layer may be located between the substantially impermeable barrier layer and the indicator material.

The semi-permeable barrier layer may have a thickness of between approximately 1 μm and approximately 100 μm.

The semi-permeable barrier layer may be selected from one or more of the group consisting of: polyethylene, polyethylene terephthalate, low density polyethylene, polypropylene, polyurethane and polyvinyl chloride.

The semi-permeable barrier layer may comprise low density polyethylene.

The substantially impermeable barrier layer may have a thickness of between approximately 12 μm and approximately 100 μm.

The substantially impermeable barrier layer may be selected from one or more of the group consisting of: polyethylene terephthalate, ethylene vinyl alcohol, polyvinylidene chloride, polyvinyl acetate, polypropylene, polyester and aluminium oxide coated polyethylene terephthalate.

The activating agent may be a chemical agent.

The activating agent may migrate to the indicator material.

The indicator device may further comprise one or more adhesive layers.

The one or more adhesive layers may be located adjacent to or between one or more of the sections, layers, materials and/or agents.

The one or more adhesive layers may have a thickness of between approximately 1 μm and 3 μm.

The one or more adhesive layers may be selected from one or more of the group consisting of: a rubber based hot melt, an acrylic adhesive, a varnish coated adhesive, an adhesive kill treated adhesive, a treated or coated permanent acrylic, a treated or coated peelable acrylic, a UV curing adhesive, a pressure sensitive adhesive, and UV curable pressure sensitive adhesive.

The substantially impermeable barrier layer may comprise a detachable section and optionally a fixed section.

Where the detachable section and the fixed section meet there may be provided a separable portion. The separable portion may be a substantially continuous cut line.

The detachable section and the fixed section may be adjacent. The detachable section and the fixed section may be separate from each other. The detachable section and the fixed section may be separated by a substantially continuous cut line. The detachable section and the fixed section may be in physical contact with each other.

The detachable section and the fixed section may be connected by a frangible portion.

The frangible portion may be a perforated portion.

The indicator device may further comprise a first adhesive layer located between or adjacent to the substantially impermeable barrier layer and the indicator material.

The first adhesive layer may be arranged such that it is in contact with the fixed section, the detachable section and the separable portion, and wherein at least part of the detachable section is adhesive free.

The separable portion may be sealed, the seal configured to mitigate the activating agent and the indicator material from coming into contact with each other.

The first adhesive layer may be located adjacent to the substantially impermeable barrier layer and arranged such that it covers at least the separable portion, thereby sealing the separable portion.

The majority of the detachable section may be adhesive free.

The first adhesive layer may be arranged in a pattern having an outer adhesive layer and an inner adhesive layer, the separable portion being positioned between the outer adhesive layer and the inner adhesive layer.

The inner adhesive layer may define an enclosed space. The inner adhesive layer may be in the shape of a ring or the like. At least part of the indicator material may be surrounded by the inner adhesive layer.

The inner adhesive layer may wholly surround the indicator material.

The first adhesive layer may be located between or adjacent to the substantially impermeable barrier layer and a support section or a substrate layer.

The adhesive used for the inner adhesive layer may be of a lower adhesive strength than the adhesive used for the outer adhesive layer.

The inner adhesive layer may be a pressure sensitive adhesive and the outer adhesive layer may be a permanent bond laminating adhesive.

The ring of adhesive may have a width of from about 0.3 mm to about 0.9 mm.

The indicator device may further comprise a second adhesive layer located between or adjacent to the substantially impermeable barrier layer and the activating agent.

The second adhesive layer may be arranged in a pattern having an outer adhesive layer and an inner adhesive layer, the separable portion being positioned between the outer adhesive layer and the inner adhesive layer.

The inner adhesive layer may define an enclosed space.

The inner adhesive layer may be in the shape of a ring or the like.

At least part of the activating agent may be surrounded by the inner adhesive layer.

The inner adhesive layer may wholly surround the activating agent.

The second adhesive layer may be located between or adjacent to the substantially impermeable barrier layer and the activator section.

The adhesive used for the inner adhesive layer may be of a lower adhesive strength than the adhesive used for the outer adhesive layer.

The inner adhesive layer may be a pressure sensitive adhesive and the outer adhesive layer may be a permanent bond laminating adhesive.

The ring of adhesive may have a width of from about 0.3 mm to about 0.9 mm.

The first and/or the second adhesive layer may have a thickness of between approximately 1 μm and 3 μm.

The first and/or the second adhesive layer(s) may be selected from one or more of the group consisting of: a rubber based hot melt, an acrylic adhesive, a varnish coated adhesive, an adhesive kill treated adhesive, a treated or coated permanent acrylic, a treated or coated peelable acrylic, a UV curing adhesive, a pressure sensitive adhesive, and UV curable pressure sensitive adhesive.

The detachable section may further comprise a tab, optionally a pull-tab.

The detachable section may be peelable or may comprise a peel mechanism.

The indicator device may further comprise a support section.

The support section may comprise a barrier layer that is substantially impermeable to the activating agent.

The indicator section may comprise a substrate material.

The indicator material may be incorporated into a discrete indicator layer and the substrate material may be incorporated into a discrete substrate layer, separate to the indicator layer.

The substrate layer may have a thickness of between approximately 12 μm and approximately 100 μm.

The substrate material may be selected from one or more of the group consisting of: aluminium oxide foil, polypropylene, and polyethylene terephthalate.

The indicator layer may have a thickness of between approximately 1 μm and approximately 3 μm.

The indicator material may comprise a polymer binder optionally selected from one or more of the group consisting of: polyvinyl butyral (PVB), nitrocellulose (NC), polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), polyethylene glycol (PEG) and polyethylenimine (PEI).

The indicator material may comprise a polymer binder optionally selected from one or more of the group consisting of: polyvinyl butyral (PVB), hydroxypropyl cellulose (HPC), polyethylene glycol (PEG) and polyethylenimine (PEI).

The indicator layer may comprise a plasticiser optionally selected from one or more of the group consisting of: tributyl phosphate, diisodecyl adipate, tris-2-ethylhexyl phosphate, tributyl phosphate, glycerol and dimethyl phthalate.

Optionally, the indicator material and the substrate material are incorporated into the same layer so-forming a combined indicator and substrate layer, and wherein the indicator material is dispersed within the substrate material or vice versa.

The combined indicator and substrate layer may comprise a polymer composite, said polymer composite comprising at least one thermoplastic polymer, and at least one chemical indicator dispersed in the at least one thermoplastic polymer, the at least one chemical indicator comprising a particulate inorganic substrate, and at least one indicator material, reactive dye or ink coated on and/or impregnated within the particulate inorganic substrate.

The combined indicator and substrate layer may have a thickness of between approximately 30 μm and approximately 100 μm.

The indicator material may be selected from one or more of the group consisting of: a redox sensitive material, a carbon monoxide sensitive material, a carbon dioxide sensitive material, an oxygen sensitive material, an amine sensitive material, an ammonia sensitive material, a pH sensitive material, and an acid sensitive material.

The pH sensitive material may be selected from one or more of the group consisting of: m-Cresol Purple (MCP, Hydroxy triarylmethane), Thymolphthalein (3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-2-benzofuran-1-one), o-Cresolphthalein (3,3-Bis(4-hydroxy-3-methylphenyl)-1(3H)-isobenzofuranone), Acryloly florescein (AcF1), 13-methyl umbelliferon (BMUB), Bromothymol blue (BTB, Hydroxy triarylmethane), 5′ and 6-Carboxyseminaphtholfluorescein (c-SNAFL), S′ and 6′-Carboxyseminaphtholrhodamine (c-SNARF), Cresol Red (CR, o-Cresolsulfonephthalein), 2-(2,4-Dinitrophenylaxo)-1-naphthol-3,6-disulphonic acid (DNPA), tris(thenoyltrifluoroacetonato) europium (III) (Eu(tta)1), Fluorescein (Fl, resorcinolphthalein), 7-hydroxycoumarin-4-acetic acid (HCA), 1, Hydroxypyrene-3,6,S-trisulphonic acid (HPTS), Neutral red (NR, toluylene red), Phenol Red (PR, phenolsulfonphthalein), Rhodamine 6G (R6G), Sulforhodamine 101 (SRh), Thymol blue (TB, thymolsulphonephthalein), Texas Red hydrazine (THR), Phenolphthalein (3,3-bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one), Thymol blue, Phenoltetraiodophthalein, Phenoltetrachlorophthalein, α-Naphtholbenzein and p-Xylenol blue.

The pH sensitive material may be selected from one or more of the group consisting of: Phenol Red (PR, phenolsulfonphthalein), m-Cresol Purple (MCP, Hydroxy triarylmethane) and Cresol Red (CR, o-Cresolsulfonephthalein).

The pH sensitive material may have a pKa value equal to or greater than approximately 7.9, optionally equal to or greater than approximately 8.3, optionally equal to or greater than approximately 8.32.

The pH sensitive material may have a pKa value of between approximately 7.9 and approximately 8.3, optionally between approximately 7.9 and approximately 8.32.

The pH sensitive material may be an acid sensitive material.

The indicator device may further comprise a release section adjacent a support section and detachable therefrom.

An adhesive layer may be located between the release section and the support section.

The release section may comprise a release layer.

The release layer may have a thickness of between approximately 50 μm and approximately 100 μm, optionally between approximately 60 μm and approximately 70 μm.

The release layer may be selected from one or more of the group consisting of: glassine, siliconised glassine paper, and a silicon treated polymer.

The indicator section, the activator section and the support section may be located between the release section and the barrier section.

The activating agent may be at least one of an oxidising agent, water, carbon dioxide, amines, acids, carboxylic acids, ammonium hydroxide and ammonia.

The activating agent may be an acid.

The activating agent may be an organic acid.

The acid may be selected from one or more of the group consisting of: aromatic acids, aliphatic acids, and cyclic acids.

The acid may be selected from one or more of the group consisting of: aromatic carboxylic acids, aliphatic carboxylic acids, and cyclic carboxylic acids.

The acid may be selected from one or more of the group consisting of: benzoic acid, o-toluic acid (2-methylbenzoic acid), 4-ethylbenzoic acid, 2,4-dimethyl benzoic acid, p-toluic acid (4-methylbenzoic acid), salicylic acid (2-hydroxybenzoic acid), decanoic acid, undecanoic acid, dodecanoic acid, 4-methylnonanoic acid, 4-ethyloctanoic acid, 1-Methyl-1-cyclohexanecarboxylic acid, 2-butyloctanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, 3-hydoxybenzoic acid, 4-hydroxybenzoic acid, cyclohexanecarboxylic acid, nonanoic acid, and cyclohexaneacetic acid.

The acid may have a melting point of at least approximately 20° C., optionally between approximately 20° C. and approximately 220° C., optionally between approximately 27° C. and approximately 217° C.

The acid may have a molecular weight of between approximately 100 gmol−1and approximately 300 gmol−1, optionally between approximately 120 gmol−1and approximately 230 gmol−1, optionally between approximately 122 gmol−1and approximately 200 gmol−1.

According to a second aspect of the invention, there is provided a package or packaging comprising the indicator device as described in the first aspect.

According to a third aspect of the invention there is provided a tape or film comprising the indicator device as described in the first aspect.

According to a fourth aspect of the invention, there is provided a method of detecting the passage of time, comprising the steps of:a) providing an indicator device as described in the first aspect;b) activating the indicator device; andc) subsequently detecting a visible change in the indicator material whereby the passage of time is revealed.

According to a fifth aspect of the invention, there is provided a method of detecting whether a sealed package has been compromised, comprising the steps of:a) providing an indicator device as described in the first aspect;b) activating the indicator device; andc) subsequently detecting a visible change in the indicator material whereby the compromise of the package is revealed.

The alternative features and different embodiments as described apply to each and every aspect and each and every embodiment thereof mutatis mutandis.

A particulate inorganic substrate is understood to be defined as a substrate which is typically made of an insoluble material, and which is provided in a particulate form. This typically includes inorganic fillers and/or inorganic pigments, which may be white, transparent, or coloured. In the context of the invention an insoluble material is understood to be defined as a material that is insoluble in a water-based or organic solvent in which the indicator material or composition ink is intended to be dissolved, prior to coating and/or impregnating within the particulate inorganic substrate.

The particulate inorganic substrate may be in powder form. Typically, the particulate inorganic substrate may be an inorganic pigment, e.g. silica, titania, alumina, magnesium oxide, calcium oxide or a zeolite.

The at least one chemical indicator may be substantially uniformly dispersed in the at least one polymer.

The polymer composite may comprise a melt-processed polymer composite, preferably extruded, and may be provided in the form of e.g. a film, sheet, tube, or any other suitable profile.

The at least one thermoplastic polymer may comprise an addition polymer such as a polyolefin, e.g. polyethylene or polypropylene, or another thermoplastic addition polymer, e.g. polystyrene or a polyacrylate. Alternatively, the at least one thermoplastic polymer may comprise a condensation polymer, e.g. polycarbonate, polyether, polyester, polyamide or polyacetal.

In one embodiment, the at least one thermoplastic polymer may be a hydrophobic polymer, e.g. polyethylene. In such instance, the at least one chemical indicator may comprise a hydrophobic particulate inorganic substrate, e.g. hydrophobic silica or hydrophobic alumina.

The indicator device of the present invention can be applied to foodstuffs and the like by end users in the home. Alternatively, it can be used in a commercial setting such as the catering and retail industries. The indicator device enables accurate assessment of the amount of time since a foodstuff was first exposed to air or opened, or the amount of time since a foodstuff was prepared. The indicator device can be used to indicate when a sealed package has been compromised. Therefore, the indicator device can be used to indicate when a foodstuff is no longer fit for consumption or it can be used to show when a sealed package has been opened. This helps to prevent both consumption of unfit foodstuffs and the unnecessary disposal of consumable foodstuffs.

