Process for expanding polytetrafluoroethylene and products produced thereby

摘要

A process for producing a shaped porous article includes the steps of providing an extrudate of a fluoropolymer material which is capable of being stretched and bilaterally stretching the extrudate along a longitudinal axis. The stretching step is carried out under conditions sufficient to yield an article which is substantially uniformly stretched over a major portion of its length. After stretching, the material has a unique through-pore microstructure characterized by elongate nodes connected by fibrils. The stretched material is sintered while being maintained in its stretched state to produce the shaped porous article. A significant feature of the inventive process is that stretching is carried out by displacing both ends of the extruded material as opposed to known method wherein only one end of an extruded material is stretched, resulting in a microporous fluoropolymer article which are different than conventional fluoropolymer stretching/expansion processes.