Development In Base-Resistant Fluoroelastomers 2003-01-0944

FEPM alternating dipolymers of tetrafluoroethylene (TFE) and propylene (P) are well known to exhibit distinguished chemical resistance, especially against various organic and inorganic bases, compared to conventional fluoroelastomers (FKM): e.g., copolymers of vinylidene fluoride (VdF), hexafluoropropylene (HFP), and optionally incorporated tetrafluoroethylene (TFE). These unique characteristics have been finding automotive sealing applications where lubricants formulated with considerable quantity of additives are used. FEPM dipolymers, however, have difficulty in processing - particularly in mold release. There are TFE-P-VdF terpolymers available, which are improved in mold release. TFE-P-VdF terpolymers, however, are often pointed out that the base resistance is lost to some extent, because the minimum quantity of VdF necessary to establish a practical cure speed and physical properties is not very low. It has been difficult to develop a terpolymer with a minimized content of VdF, which is cured easily and maintains the base resistance of the original FEPM dipolymer.

In this work, controlled polymerization, formulation and compounding technologies achieved a success in minimizing the VdF unit copolymerized into TFE-P polymer structure. Only a small quantity of VdF unit effectively behaves as a cure site for both bisphenol and peroxide cure systems. This new polymer exhibits excellent curability and processability, especially mold release, without losing base resistance.