Patent ID: 11919323
Assignee: XEROX CORPORATION
Field: Textile and paper machines (Mechanical engineering)
Classification: CPC B  G | IPC B  G

Claim 14:
15. A color changing expiration indicator comprising:
a reactive layer;
a first barrier layer that covers at least a portion of the reactive layer, wherein the first barrier layer includes first pores;
a first transmission layer that covers at least a portion of the first barrier layer;
a second barrier layer that covers at least a portion of the first transmission layer and a third barrier layer that covers at least a portion of the transmission layer, wherein the second barrier layer includes second pores and the third barrier layer includes third pores, wherein the third pores, the second pores, and the first pores form paths through the transmission layer, wherein the first pores and the second pores are offset from one another and the first pores and the third pores are aligned with one another such that each of the paths includes both a lateral pathway portion and a vertical pathway portion through which the reactive layer has to traverse;
a second transmission layer that covers at least a portion of the second barrier layer;
a reactant layer that covers at least a portion of the second barrier layer, wherein the reactant layer changes color responsive to a reaction that occurs between the reactant layer and the reactive layer; and
a protective coating that covers at least a portion of the reactive layer, the first barrier layer, the first transmission layer, the second barrier layer, the second transmission layer, and the reactant layer;
wherein the reaction occurs on an expiration date, and wherein a thickness of the transmission layer is based at least in part on the expiration date to control timing of the reaction.