Polyolefin/copolyamide RF active adhesive film

Abstract

Flexible, halogen-free, high frequency-sealable films fabricated from a blend of a copolyamide and a polyolefin having a carboxylic acid or carboxylic acid anhydride functionality have sufficient copolyamide to yield a DLF of at least 0.05 at a frequency of 27 megahertz and serve as effective substitutes for flexible polyvinyl chloride films. The films may be mono-layer films or multi-layer films, especially where the high frequency-sealable films serve as outer or skin layers in multi-layer films. Products made from such mono-layer and multi-layer films find utility in a number of applications, especially for medical device applications.

What is claimed is:  
     
         1 . A polymeric composition suitable for fabrication into a radio frequency weldable film structure, the composition consisting essentially of a blend of a copolyamide and a polyolefin that has a carboxylic acid anhydride functionality, the blend having a dielectric loss factor of at least 0.05 at a frequency of 27 megahertz at 23° centigrade, the copolyamide being present in an amount with a range of from 20 to 80 percent by weight, based on total blend weight.  
     
     
         2 . The composition of  claim 1 , wherein the copolyamide is derived from a dimeric fatty acid.  
     
     
         3 . The composition of  claim 1 , wherein the polyolefin has polymerized therein at least one monomer that is an ethylenically unsaturated carboxylic acid anhydride.  
     
     
         4 . The composition of  claim 1 , wherein the polyolefin is a base polyolefin having grafted thereto at least one monomer selected from the group consisting of ethylenically unsaturated carboxylic acid anhydrides.  
     
     
         5 . The composition of  claim 4 , wherein the base polyolefin is selected from the group consisting of linear low density polyethylene, low density polyethylene, ultra low density polyethylene, copolymers of ethylene and at least one alpha-olefin monomer, linear ethylene/alpha-olefin copolymers, substantially linear ethylene/alpha-olefin copolymers, propylene polymers and copolymers and copolymers of ethylene and less than 30 weight percent, based on copolymer weight, of a polar monomer.  
     
     
         6 . The composition of  claim 5 , wherein the polar monomer is selected from the group consisting of vinyl acetate, methyl acrylate, acrylic acid and methacrylic acid.  
     
     
         7 . The composition of  claim 5 , wherein the alpha-olefin monomer contains from 3 to 20 carbon atoms.