Polyimide

摘要

A polymer having recurring units of the formula where R is a divalent radical of the formula and n is a whole number greater than 10, may be obtained by reacting a compound of the formula with a diamine of the formula H2N-R-NH2 in an organic solvent. The polymers may also be obtained by forming the monomer in situ by reacting N,N1-diphenyl-p-phenylene diamine with chloroformyl phthalic anhydride and then adding a second diamine required to make the polymers in a suitable solvent. They generally have softening points in the range 275 DEG to 375 DEG C. Conventional additives may be added to the polymers (they may also be blended with other polymers) and they may be used as laminating resins, formed into films, filaments or fibres or they may be moulded into shaped articles. The dianhydride monomers may also be used to effect curing of epoxy resins by incorporating small amounts of the dianhydride in an epoxy resin and heating the latter at 150-175 DEG C.ALSO:A novel dianhydride of the formula may be obtained by reacting 4-chloroformyl phthalic anhydride with N,N1 - diphenyl - p - phenylene diamine. The reaction may be effected in an inert organic solvent.ALSO:A coating composition comprises a polymer of the formula: where R is a divalent radical of the formula and n is a whole number greater than 10. The polymers may be coated on metallic or non-metallic substrates, e.g. glass, by flame spraying, melt casting or by casting while dissolved in a solvent. In an example a nickel-coated copper wire is dipped into a solution of a polymer of the formula: in N-methyl pyrrolidone and cured at 300 DEG C for 3 minutes for each of three coats.