| abstract |
The present invention relates to a method for improving both adhesion between substrate and polymer layers and the durability of such composite structures; while maintaining the malleability and preferred characteristics of the original substrate. Quite unexpectedly, the application of a layer or film upon an uncured, encapsulated base substrate which has been encapsulated by the shear thinning methods of the present invention, results in superior adhesion of multiple layers when compared to conventional layering, coating or composite manufacturing methods. Moreover, the uncured or at most, semi-cured, polymer composition applied to the base substrate ensures that the substrate maintains maximum flexibility for subsequent shaping into composite articles prior to curing. The methods described herein produce multiple layer composite articles that are lighter, stronger, more flexible and utilize less material, than composite articles produced by conventional techniques.The method comprises applying an uncured, substantially solvent free, polymer composition exhibiting thixotropic or pseudoplastic characteristics, onto a base substrate having structural elements and interstices therebetween; shear thinning the polymer composition to place it into the base substrate, thereby encapsulating most of the structural elements while leaving a plurality of interstitial spaces open; overlaying a layer or film of polymer or thermoplastic material to at least one surface of the uncured encapsulated base substrate; pressuring the layer or film into the interstices of the uncured encapsulated base substrate to form a chemical and mechanical interlocking bond between the polymer composition of the base substrate and the overlay material; and optionally shaping the multi layer composite and curing the completed composite. This method produces multi layer composite articles and medical garments exhibiting increased adhesion and durability with excellent malleability and flexibility over conventional methods. |