Composite structure including a low vinyl acetate layer

Abstract

A composite structure suitable for making transdermal delivery devices includes in sequence: (a) a liner film layer; (b) a containment layer having from zero to 15 wt % content of vinyl acetate repeating units, the layer including either a thermal bonding copolyester resin or a combination of an ethylene-vinyl acetate component and a nonpolar polymer; and (c) a polyester film layer less than 20 μm in thickness. A drug layer lies either between the liner film layer and the containment layer or within a concave depression in the containment layer. A composition including an ethylene-vinyl acetate component and an ABA block copolymer, wherein the A segments of the block copolymer are styrenic segments, is also provided. The composition includes between 1 and 15 wt % of vinyl acetate repeating units, based on the total weight of composition exclusive of any solvents.

1 . A composite structure comprising in sequence: 
 (a) a liner film layer;    (b) a containment layer having from zero to 15 wt % content of vinyl acetate repeating units, the layer comprising either a thermal bonding copolyester resin or a combination of an ethylene-vinyl acetate component and a nonpolar polymer; and    (c) a polyester film layer less than 20 μm in thickness;    the composite structure further comprising a drug layer either between the liner film layer and the containment layer or within a concave depression in the containment layer; said depression facing the liner film layer.    
   
   
       2 . The composite structure of  claim 1 , wherein the containment layer comprises said combination of an ethylene-vinyl acetate component and a nonpolar polymer, the nonpolar polymer comprising an ABA block copolymer wherein the A segments of the block copolymer are styrenic segments.  
   
   
       3 . The composite structure of  claim 1 , wherein the containment layer comprises said combination of an ethylene-vinyl acetate component and a nonpolar polymer, said containment layer having a thickness of less than 20 μm.  
   
   
       4 . The composite structure of  claim 1 , wherein the polyester film layer comprises a mechanically abraded polyester film having a 600 gloss less than 15%.  
   
   
       5 . The composite structure of  claim 2 , wherein the containment layer comprises between 1 and 15 wt % of vinyl acetate repeating units.  
   
   
       6 . The composite structure of  claim 2 , wherein the B segments of the block copolymer are saturated aliphatic segments.  
   
   
       7 . The composite structure of  claim 5 , wherein the ethylene-vinyl acetate component constitutes between 35 and 75 wt % of a combined weight of the ethylene-vinyl acetate component and the ABA block copolymer.  
   
   
       8 . The composite structure of  claim 5 , wherein the ethylene-vinyl acetate component comprises between 25 and 95 wt % of a first EVA polymer containing between 26 and 30 wt % of vinyl acetate repeating units and between 25 and 95 wt % of a second EVA polymer containing between 31 and 35 wt % of vinyl acetate repeating units.  
   
   
       9 . The composite structure of  claim 8 , wherein the ethylene-vinyl acetate component further comprises between 5 and 25 wt % of a third EVA polymer containing between 36 and 42 wt % of vinyl acetate repeating units.  
   
   
       10 . The composite structure of  claim 1 , wherein the drug layer is within said concave depression in the containment layer.  
   
   
       11 . The composite structure of  claim 1 , wherein the drug layer is between the containment layer and the liner film layer.  
   
   
       12 . The composite structure of  claim 11 , the composite structure further comprising an adhesive layer between the containment layer and the liner film layer, the adhesive layer having a concave depression facing the liner film layer and containing the drug layer.  
   
   
       13 . The composite structure of  claim 1 , further comprising an adhesive layer on a surface of the liner film layer facing the drug layer.  
   
   
       14 . The composite structure of  claim 13 , further comprising a membrane between the adhesive layer and the drug layer.  
   
   
       15 . The composite structure of  claim 1 , further comprising a primer layer comprising a polymer selected from the group consisting of polyacrylates, ethylene-acrylic acid copolymers, amorphous polyesters, polyethylenimines, and polyvinylidene chlorides.  
   
   
       16 . The composite structure of  claim 15 , wherein the polymer is an ethylene-acrylic acid copolymer.  
   
   
       17 . The composite structure of  claim 16 , wherein the primer layer is between the drug layer and the containment layer.  
   
   
       18 . The composite structure of  claim 16 , wherein the primer layer is on a surface of the polyester film layer facing the drug layer.  
   
   
       19 . The composite structure of  claim 1 , wherein the containment layer comprises a thermal bonding copolyester resin.  
   
   
       20 . The composite structure of  claim 19 , further comprising a primer layer on a surface of the containment layer facing the drug layer.  
   
   
       21 . A composition comprising an ethylene-vinyl acetate component and an ABA block copolymer wherein the A segments of the block copolymer are styrenic segments, the composition comprising between 1 and 15 wt % of vinyl acetate repeating units, based on the total weight of composition exclusive of any solvents.  
   
   
       22 . The composition of  claim 21 , wherein the B segments of the block copolymer are saturated aliphatic segments.  
   
   
       23 . The composition of  claim 21 , wherein the ethylene-vinyl acetate component constitutes between 35 and 75 wt % of a combined weight of the ethylene-vinyl acetate component and the ABA block copolymer.  
   
   
       24 . The composition of  claim 21 , wherein the ethylene-vinyl acetate component comprises between 25 and 95 wt % of a first EVA polymer containing between 26 and 30 wt % of vinyl acetate repeating units and between 25 and 95 wt % of a second EVA polymer containing between 31 and 35 wt % of vinyl acetate repeating units.  
   
   
       25 . The composition of  claim 24 , wherein the ethylene-vinyl acetate component further comprises between 5 and 25 wt % of a third EVA polymer containing between 36 and 42 wt % of vinyl acetate repeating units.  
   
   
       26 . A method of making a composite structure, the method comprising in sequence: 
 (a) applying to a surface of a substrate a liquid mixture comprising a diluent, an ethylene-vinyl acetate component, and a nonpolar polymer; and    (b) removing the diluent to provide a coating containing between 1 and 15 wt % of vinyl acetate repeating units.    
   
   
       27 . The method of  claim 26 , wherein the nonpolar polymer comprises an ABA block copolymer wherein the A segments of the block copolymer are styrenic segments.  
   
   
       28 . The method of  claim 27 , wherein the B segments of the block copolymer are saturated aliphatic segments.  
   
   
       29 . The method of  claim 27 , wherein the ethylene-vinyl acetate component constitutes between 35 and 75 wt % of a combined weight of the ethylene-vinyl acetate component and the ABA block copolymer.  
   
   
       30 . The method of  claim 26 , wherein the substrate comprises a polyester film layer less than 20 μm in thickness, the method further comprising (c) applying to the coating a drug layer.  
   
   
       31 . The method of  claim 26 , wherein the substrate comprises a polyester film layer less than 20 μm in thickness, the method further comprising: 
 (c) applying to the coating a primer layer or an adhesive layer; and    (d) applying a drug layer to the primer layer or adhesive layer.