Flexible magnetic foil or label including an optically diffractive structure

Abstract

A flexible foil or label for attachment to an object such as a document by stamping, blocking, pressure or roll application, consisting of or including a carrier layer, an optional release layer, a protective layer, a magnetic layer consisting of magnetic material having a permanently structured magnetic characteristic which varies from place to place, and an optional adhesive layer, the flexible foil having an optically diffractive structure formed in either the carrier layer, the protective layer, or the magnetic; layer. The flexible foil may include a reflective layer such as a metal layer to improve visibility of the diffractive structure.

What is claimed is:  
     
         1 . A flexible foil for attachment to an object such as a document by stamping, blocking, or roll application, consisting of or including a carrier layer, an optional release layer, a protective layer, a magnetic layer consisting of magnetic material having a permanently structured magnetic characteristic which varies from place to place, and an optional adhesive layer, the flexible foil having an optically diffractive structure formed in the carrier layer and/or the protective layer, and/or the magnetic layer.  
     
     
         2 . A flexible foil as claimed in  claim 1  including a reflective layer to improve visibility of the diffractive structure.  
     
     
         3 . A flexible foal as claimed in  claim 2  in which the reflective layer consists of a metal.  
     
     
         4 . A flexible label for attachment to an object such as a document by pressure, or roll application, consisting of or including a substrate layer, a magnetic layer consisting of magnetic material having a permanently structured magnetic characteristic which varies from place to place, and an adhesive layer, the flexible label having an optically diffractive structure formed in the substrate layer.  
     
     
         5 . A flexible label as claimed in  claim 4  including a reflective layer to improve visibility of the diffractive structure.  
     
     
         6 . A flexible label for attachment to an object such as a document by pressure, or roll application, consisting of or including a substrate layer, a magnetic layer consisting of magnetic material having a permanently structured magnetic characteristic which varies from place to place, and an adhesive layer, the flexible label having an optically diffractive structure formed in the magnetic layer.  
     
     
         7 . A flexible label as claimed in  claim 6  including a reflective layer to improve visibility of the diffractive structure.  
     
     
         8 . A flexible label as claimed in  claim 7  in which the reflective layer consists of a metal.  
     
     
         9 . A, flexible label as claimed in  claim 4  in which the adhesive layer is a pressure sensitive adhesive layer.  
     
     
         10 . A flexible label as claimed in  claim 4  in which the adhesive layer is provided on the opposite side of the magnetic layer to that having the optically diffractive structure.