Method for forming inherently ink-receptive film substrates

Abstract

Ink-receptive substrates comprise a base layer formed from a water-insoluble thermoplastic polymer, and an ink-receptive layer disposed over the base layer. The ink-receptive layer is formed from a melt-processable blend of a water-soluble polymer and a substantially water-insoluble polymer, and provides an inherently ink-receptive surface without further surface treatment. The ink-receptive blend comprises in the range of from 20 to 80 percent by weight water-soluble polymer, and in the range of from 20 to 80 percent by weight substantially water-insoluble polymer based on the total weight of the blend. The blend has a melting temperature in the range of from about 100 to 600° F. Preferred water-soluble polymers include polyvinyl alcohols and polyalkyl oxazolines. Preferred ink-receptive substrates of this invention comprise a base layer and ink-receptive layer that are formed simultaneously by coextrusion process. Ink-receptive substrates of this invention can include the ink-receptive layer on one or both surfaces of the base layer, and/or can be constructed in the form of a pressure-sensitive adhesive label, i.e., with a pressure-sensitive adhesive material disposed on a surface of the base layer opposite the ink-receptive layer.

1 . A method for forming an ink-receptive substrate comprising the steps of: 
 forming a melt-processable base layer from a water-insoluble thermoplastic polymer; and    simultaneously forming an ink-receptive layer over the base layer from a blend of a water-soluble polymer and a substantially water-insoluble polymer, wherein the ink-receptive layer provides a printable surface that is inherently ink-receptive without subsequent treatment.    
     
     
         2 . The method as recited in  claim 1 , further comprising the step of forming a tie layer over the base layer before the step of forming the ink-receptive layer, the tie layer being formed from a thermoplastic polymer and being formed simultaneously with the base layer and ink-receptive layer.  
     
     
         3 . The method as recited in  claim 1 , further comprising the step of forming an adhesive layer over a surface of the base layer opposite from the ink-receptive layer to provide a label.  
     
     
         4 . The method as recited in  claim 1 , wherein the base layer and ink-receptive layer are formed by coextrusion.  
     
     
         5 . The method as recited in  claim 1  wherein the substantially water-insoluble polymer is a polyolefin, and the water-soluble polymer is selected from the group of compounds consisting of polyvinyl alcohols, polyalkyl oxazolines, polyphenyl oxazolines, polyvinyl pyrrolidones, polyacrylic-acids, polymethyl methacrylates, polymethacrylic acids, styrene maleic anhydrides, alkyl celluloses, carboxyalkyl celluloses, hydroxyalkyl celluloses, polyethylene oxides, polyethyleneimines, and mixtures thereof.