Mixtures of polytetrafluoroethylene and - hard insoluble polyimide,suitable for bearings

摘要

Mixtures of polytetrafluoroethylene and hard insoluble polyimide, suitable for bearings to run against metal surfaces They contain 5-95 vol.% of a polyimide prepd. from (a) a mixture of (i) R(COOH)4 or its dianhydride or di- or tetra-ester, and/or an organic tricarboxylic acid with 2 COOH groups in o- or p-position, or its anhydride or mono-, di- or tri-ester, and (ii) Z-CO-NH-R1-NH-CO-Z1, or (b) a dicarboxylic acid deriv., of formula: Z-CO-NH-R11(COOH)2 or corresponding deriv. of the dianhydride of mono- or di-ester, or (c) a pre-polymer obtained from (i) + (ii) or from (b). R and R11 are aromatic tetra- or tri-valent residues with the CO groups in o- or p-position, R1 is a divalent aromatic residue, Z and Z1 are -R111, or -NRV1, and R111, R1111, RV and RV1 are monovalent aliphatic or aromatic hydrocarbon residues; R1111, RV and RV1 also have no terminal methylene groups.