Patent ID: 7736576

Claim:
A continuous process for modifying a material surface, comprising the steps of: a) providing an expanded polytetrafluoroethylene material having a surface comprised of nodes interconnected by fibrils, the fibrils having lengths; b) exposing the expanded polytetrafluoroethylene surface to an unfocused laser beam to elongate fibrils and shorten fibrils to form node clusters; c) exposing the polytetrafluoroethylene surface having said node clusters to an unfocused laser beam to remove the surface portion of some nodes and some elongated fibrils, thereby producing a material having said node clusters, valleys, and rough gnarled nodes connected by fibrils disposed on the valley floor; and, next d) exposing the material having said node clusters, valleys, and said rough gnarled nodes connected by fibrils, to an unfocused laser beam to remove the fibrils connecting said rough gnarled nodes to form gnarled nodes, said gnarled nodes having a protruding length and being substantially devoid of fibrils along the protruding length.