Time temperature indicator label
AssigneeIntray Limited
InventorsJohn Robinson, Stephen Wintersgill, Andy Hancock, Martin Peacock, Sarah Akbar, Brunella Maranesi
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Abstract
A time-temperature integrating (TTi) indicator label comprises an initiator reservoir and a target reservoir, said initiator reservoir containing a pH modification system and said target reservoir comprising a pH responsive indicator. The pH responsive indicator may be photo-initiated. There is also provided a time-temperature indicator label comprising first and second reservoirs separated by a hydrogel valve, said valve allowing passage of an acid from said first reservoir to said second reservoir when the hydrogel valve is activated.
Claims67
A time-temperature integrating (TTi) indicator label comprises an initiator reservoir and a target reservoir, said initiator reservoir containing a photoinitiated pH modification system and said target reservoir comprising a pH responsive indicator, wherein the label further comprises a third reservoir comprising a temperature-dependent timing mechanism comprising at least one of a diol, a polyol, a water-soluble polymer, and a gel.
A label according to any preceding claim, wherein said pH modification system comprises an acid generation system.
A label according to any preceding claim, further characterised in that said initiator and target reservoirs are separate portions of the same physical reservoir.
A label according to any preceding claim, wherein said initiator and target reservoirs are physically separate, distinct reservoirs.
A label according to any preceding claim, further characterised in that said initiator reservoir is at least partially filled with a hydrogel polymer.
A label according to any preceding claim, further characterised in that at least a portion of said initiator reservoir is arranged such that it can be exposed to light.
A label according to any preceding claim, further characterised in that at least a portion of said target reservoir is visible from outwith said label to allow visual inspection thereof.
A label according to any preceding claim, said reservoirs being arranged in series, initiator to accumulator to target reservoir.
A time-temperature indicator label according to any preceding claim comprising an initiator reservoir, an accumulator reservoir and a target reservoir arranged in series, said reservoirs each being separated by a pH responsive hydrogel polymer plug, said initiator reservoir containing a PAG, said initiator reservoir further being provided with a substantially light impermeable, peelable cover such that it can be selectively exposed to light, said accumulator reservoir further containing a hydrogel polymer matrix or a high viscosity medium;
- said target reservoir further containing a pH indicator compound;
- such that upon removal of said peelable layer said PAG is exposed to light, said PAG reacts to generate hydrogen ions, said hydrogen ions then causing the de-swelling of the first pH responsive hydrogel polymer plug, allowing ingress of said hydrogen ions into said accumulator reservoir, the contents of said accumulator reservoir hence becoming gradually more acidic as the hydrogen ions diffuses in from said initiator reservoir;
- subsequently, as the level of hydrogen ions in said accumulator reservoir accumulates to a sufficient level said hydrogen ions causes the de-swelling of said second pH responsive hydrogel polymer plug, thereby allowing ingress of said hydrogen ions into said target reservoir wherein said hydrogen ions interacts with said pH indicator compound to effect a colour change, said colour change being observable by the user through a viewing pane incorporated into said target reservoir.
A label according to any preceding claim, further comprises a three layer, laminar construction comprising a base layer, an intermediate layer and a top layer.
A label according to any preceding claim, further characterised in that said target reservoir further contains one or more pH reactive inks arranged to enhance the colour change of said acid responsive indicator.
A label according to any preceding claim, further characterised in that said stimuli-responsive hydrogel polymers are selected from the group comprising poly (vinyl alcohol)/poly (acrylic acid) [PVA/PAA];
- poly (methacrylic acid) [PMAA] and 2-(dimethylamino) ethylmethacrylate/N-vinyl pyrrolidone [DNAEMA/NVP].
A label according to any preceding claim, wherein photo-initiated acid generation system comprises a photosensitiser.
A time-temperature indicator label comprising first and second reservoirs separated by a hydrogel valve, said valve allowing passage of an acid from said first reservoir to said second reservoir when the hydrogel valve is activated, the label further comprising a temperature-dependent timing mechanism comprising at least one of a diol, a polyol, a water-soluble polymer and a gel.
A time-temperature indicator label substantially as hereinbefore described with reference to the claims and description.
Dependencies are inferred from the claim text.