3 - Manufacture

Abstract

Fluorinated ionomers are produced in relatively small volumes. For the economics of manufacture it is therefore important to integrate the manufacture with that of similar, larger volume products. This chapter describes monomer synthesis, copolymerization, fabrication, including lamination to a reinforcement, and finishing in enough detail to allow the manufacture of these products on a laboratory scale. It then gives the procedures to adjust the parameters of equivalent weight (EW) and melt flow (MF) during copolymerization. A laboratory chlor-alkali cell is described in a way that will allow testing in its most important application, particularly in direct comparison with commercially available membrane types. For perfluorinated ionomers, the monomer synthesis can be integrated with that of other vinyl ether monomers such as perfluoro propyl vinyl ether (PPVE) or perfluoro methyl vinyl ether (PMVE). For partially fluorinated ionomers, it is possible to use radiation grafting of certain monomers on commercially available fluoropolymer films such as fluorinated ethylene propylene (FEP) copolymer. While this approach may lead to attractive economics, the oxidative stability of the products obtained has been poor. The important raw materials for the preparation of perfluorinated ionomers are TFE and hexafluoro propylene epoxide (HFPO). The synthesis of these two materials must be discussed to fully understand the process.