Packaging material and products comprising indicia-former which changes from a first visual condition to a second visual condition and indicates a characteristic of the package contents

A flexible material which comprises:

• a) a thin film substrate which is substantially transparent to radiant energy;
• b) an absorbent material associated with at least a portion of the substrate, said absorbent material being sufficiently opaque to radiant energy to absorb said radiant energy and convert said energy into heat energy;
• and
• c) at least one indicia-former carried by said film substrate which undergoes conversion from a first visual condition to a second visual condition upon exposure to heat energy from said absorbent material.

A heat-shrinkable flexible packaging film, said film having at least one energy sensitive indicia-former on the surface thereof, said film comprising:

• a) a thin film substrate which is flexible and shrinks when heated, and which is substantially transparent to radiant energy, thereby remaining substantially unchanged on exposure to radiant energy;
• b) an absorbent material associated with at least a portion of said substrate, said absorbent material being sufficiently opaque to radiant energy to absorb said energy and convert said radiant energy into heat energy, with said heat energy being transferred to said indicia-former;
• and
• c) said energy sensitive indicia-former carried by said film being caused to undergo conversion from a first visual condition to a second visual condition upon exposure to said heat energy.

In combination, an open-top container, the open top of which is covered by a heat-shrinkable flexible packaging film, said film comprising:

• a) a thin film substrate which is flexible and shrinks when heated, and which is substantially transparent to radiant energy, thereby remaining substantially unchanged by radiant energy;
• b) an absorbent material associated with at least a portion of said substrate, said absorbent material being sufficiently opaque to radiant energy to absorb said radiant energy and convert said radiant energy into heat energy;
• and
• c) an energy sensitive indicia-former carried by said film and comprising an ink formulation which undergoes conversion from a first visual condition to a second visual condition upon exposure to heat energy converted from the absorbent material.