초록

A method of monitoring if a stored product has exceeded a predetermined temperature using an assembly, which comprises coated onto a carrier a gelatin layer containing an acidic reactant, color former and an encapsulated non-aqueous solvent.

대표청구항 ▼

A method of monitoring if a stored product has exceeded a predetermined lower temperature but is still below a predetermined higher temperature which comprises forming on a carrier in clearly separate areas two colourable compositions, wherein a first of said two colourable compositions includes a c

A method of monitoring if a stored product has exceeded a predetermined lower temperature but is still below a predetermined higher temperature which comprises forming on a carrier in clearly separate areas two colourable compositions, wherein a first of said two colourable compositions includes a colour former, an acidic reactant and a first non-aqueous solvent in which colour formation can take place when said first solvent is in a molten state at a temperature at or above said predetermined lower temperature but not when said first solvent is in a solid state at a temperature below said predetermined lower temperature, said first solvent and at least one other component of said first colourable composition being encapsulated, the capsules and the remaining component of said first colourable composition being applied to a first area of said carrier with a binder, and wherein a second of said two colourable compositions includes a colour former, an acidic reactant and a second non-aqueous solvent in which colour formation can take place when said second solvent is in a molten state at a temperature at or above said predetermined higher temperature but not when said second solvent is in a solid state at a temperature below said predetermined higher temperature, said second solvent and at least one other component of said second colourable composition being encapsulated, the capsules and the remaining component of said second colourable composition being applied to a second area of said carrier with a binder, said first composition changes colour at said predetermined lower temperature and said second composition changes colour at said predetermined higher temperature, acclimatizing the carrier and encapsulated solvents to a storage temperature of the product, said storage temperature being below said predetermined lower temperature, then when said carrier is in close proximity with the product breaking the capsules of encapsulated solvent in each of said separate areas and observing when a colour change occurs in the first colourable composition which changes colour at the predetermined lower temperature to indicate that the stored product has exceeded the said predetermined lower temperature and noting if a change in colour of the second-colourable composition has occurred which, if it has, would indicate that the stored product has exceeded also the higher predetermined temperature.