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Flexible porous web having a permanent humidity sensor for indicating release of material therefrom

  • US 4,909,179 A
  • Filed: 04/25/1988
  • Issued: 03/20/1990
  • Est. Priority Date: 04/25/1988
  • Status: Expired due to Fees
First Claim
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1. A porous web having a permanent humidity detecting sensor comprisinga porous web having a substantially porous matrix and having bonded therein a metallic salt that undergoes a color change from its hydrated to its dehydrated state, said metallic salt bonded in said matrix with a polymeric binder that permanently bonds the salt in said matrix and allows the salt to undergo a visible color change upon a change in humidity of the environment to which it is exposed, said porous matrix containing an agent for release from the matrix, said release detected by a visual observation of said color change.

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