Multi-Axis Polarizer Film For Anti-Counterfeit Applications And Method Of Making The Same

Abstract

A polarizer film is formed to include sets of polarized lines (sets of parallel lines) oriented at several directions across the surface of the film. The lines may be created using a printing process that transfers grooves from a printing plate to the film (e.g., an embossing process). A rotogravure printing process (or other suitable process) is then used to apply a liquid polarizing dye material to the printed film. The dye molecules align along all of the various grooves embossed in the film, forming a multi-axis polarizer film. The film may be used to form separate multi-axis polarizer labels (useful in anti-counterfeiting applications), and a process of easily removing the individual labels from the original film is described.

What is claimed is: 
     
         1 . A method of making a multi-axis polarizer film comprising the steps of:
 a) providing a sheet of plastic film;   b) embossing the sheet of plastic film with a plurality of sets of grooves, each set comprising several parallel grooves of a given length and each set disposed at a different location across a surface of the sheet of plastic film and oriented at a different direction with respect to a longitudinal axis of the sheet of plastic film;   c) applying a polarizing liquid dye to the embossed sheet of plastic film, wherein molecules of the polarizing liquid dye align with the plurality of sets of grooves and form multiple axes of polarization within the embossed sheet of plastic film.   
     
     
         2 . The method as defined in  claim 1  wherein the sheet of plastic film provided in step a) is a sheet of polyvinyl-alcohol (PVA) film. 
     
     
         3 . The method as defined in  claim 1  wherein the sheet of plastic film provided in step a) is a sheet of cellulose triacetate (CTA) film. 
     
     
         4 . The method as defined in  claim 1  wherein in performing step c), the polarization liquid dye comprises iodine. 
     
     
         5 . The method as defined in  claim 1 , wherein in performing step b), the embossing comprises
 1) providing a printing plate;   2) creating the plurality of sets of grooves as a pattern on a surface of the printing plate;   3) pressing the printing plate into a section of the sheet of plastic film to imprint the plurality of sets of grooves into a surface of the section of the sheet of plastic film.   
     
     
         6 . The method as defined in  claim 5  wherein steps b1) through b3) are repeated as subsequent sections of the sheet of plastic film are positioned adjacent to the printing plate. 
     
     
         7 . The method as defined in  claim 5  wherein in performing step b2), an aluminum material is used as the printing plate. 
     
     
         8 . The method as defined in  claim 5  wherein in performing step b2), a photolithographic etching process is used to create the plurality of sets of parallel grooves across the surface of the printing plate. 
     
     
         9 . A method of making anti-counterfeit polarized labels, the method comprising the steps of:
 a) providing a sheet of polarizer film formed to include an anti-counterfeit polarization pattern;   b) applying a masking layer over an exposed major surface of the polarizer film;   c) cutting through a portion of the thickness of the structure of step b) at predetermined locations defined as boundaries for individual label elements, retaining a web frame portion of the masking layer;   d) applying a covering layer over the cut surface of the masking layer so as to adhere to each cut portion of the masking layer; and   e) pulling the covering layer away from the major surface of the sheet of polarizer film, wherein the act of pulling the covering layer also removes the underlying, adhered cut portions of the masking layer.   
     
     
         10 . The method as defined in  claim 9  wherein steps b) through d) are repeated on a remaining, opposing major surface of the polarizer film, with step e) used to pull the covering layer away from both major surfaces of the polarizer film. 
     
     
         11 . The method as defined in  claim 9 , wherein step a) is further defined as providing a multi-axis polarizer film, and includes the individual steps of:
 a1) providing a sheet of plastic film;   a2) embossing the sheet of plastic film with a plurality of sets of grooves, each set comprising several parallel grooves of a given length and each set disposed at a different location along the sheet of plastic film and oriented at a different direction with respect to a longitudinal axis of the sheet of plastic film; and   a3) applying a polarizing liquid dye to the embossed sheet of plastic film, wherein molecules of the polarizing liquid dye align with the plurality of sets of grooves and form multiple axes of polarization within the embossed sheet of plastic film to create a multi-axis polarizer film.   
     
     
         12 . A multi-axis polarizer film comprising
 a sheet of plastic material including a plurality of sets of embossed grooves formed at different spatial locations across a major surface of the sheet of plastic material, each set of grooves including several parallel grooves of a given length and each set oriented at a different direction with respect to a longitudinal axis of the sheet of plastic film; and   a polarizing dye, with molecules of the polarizing dye disposed within and aligned along the plurality of sets of grooves, forming multiple axes of polarization within the embossed sheet of plastic film to form the multi-axis polarizer film.   
     
     
         13 . The multi-axis polarizer film as defined in  claim 12  wherein the sheet of plastic material comprises a sheet of polyvinyl-alcohol (PVA) film. 
     
     
         14 . The multi-axis polarizer film as defined in  claim 12  wherein the sheet of plastic material comprises a sheet of cellulose triacetate (CTA) film. 
     
     
         15 . The multi-axis polarizer film as defined in  claim 12  wherein the polarizing dye comprises iodine.