Process for making fluoropolymer composites

A process for the production of a fluoropolymer-fiber composite comprising:

• (a) preparing thin thermoplastic fluoropolymer flakes having an irregular periphery with an irregular microfibular structure extending therefrom by disc refining fluoropolymer pellets, said flakes having a Canadian Standard Freeness greater than 800, then co-dispersing said flakes with fibers in an aqueous solution to form a homogenous slurry;
• (b) feeding the slurry to a screen in a layer;
• (c) removing water from the layer;
• (d) drying the layer to form a thin self-supporting porous fluoropolymer-fiber planar preform layer;
• (e) preconsolidating said planar preform layer by heating said planar preform layer to above the melt temperature of the fluoropolymer, then applying sufficient pressure normal to the plane of the preform layer while the preform layer is unconstrained in the in-plane direction to cause the fluoropolymer to flow orienting the fibers in substantially the plane of the layer by means of said flow to form a preconsolidated sheet;
• (f) cooling said sheet;
• and
• (g) forming a solid shaped composite from a stack of said sheets by heating said stack to a high enough temperature and applying sufficient pressure for a sufficient amount of time to form said solid shaped composite.