2430257-A is referenced by 18 patents and cites 5 patents.

By printing a bar code (comprising dark and light regions) or parts of such a bar code with an ink containing a dye, which changes colour in the presence of an acid or a base to remove the contrast between the regions of the bar code, and a neutral compound which releases an acid or a base on exposure to energising radiation, a bar code can be produced that becomes unreadable after a pre-determined interval. This can be used as a time-temperature indicator to ensure that products, which might be perishable, associated with such a bar code are not used by the public. In one embodiment the dye is a leuco dye, in another embodiment the neutral compound is a cationic photoinitiator.

Title
Bar code having a time-temperature indicator
Application Number
GB20050018948 20050916
Publication Number
2430257A
Application Date
September 16, 2005
Publication Date
March 21, 2007
Inventor
Leonard Michael William
GB
Azizian Farid
GB
Assignee
Sun Chemical
GB
IPC
G01N 31/22
G01K 03/00
B65D 79/00
G01K 11/00
G01N 31/22
G01K 03/04
B65D 79/02
G01K 11/12
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