Improvements in or relating to polyimides

摘要

A polyimide has the recurring unit where R is a tetravalent radical containing at least one ring of 6 carbon atoms having benzenoid unsaturation, the four carbonyl groups being attached directly to separate carbon atoms in a ring of the R radical and each pair of carbonyl groups being attached to adjacent carbon atoms in a ring of the R radical, and R1 is a divalent benzenoid radicle of the formula , or where R11 is where R111 and R1111 are alkyl or aryl groups. The polyimides may be prepared via the corresponding polyamide acids. Many polyimide-forming reactants are specified. The examples describe the preparation of polyimides from pyromellitic dianhydride and:-(1) bis(4-aminophenyl) diethyl silane; and (2) (a) phenyl-bis-(4-aminophenyl) phosphine oxide; (b) bis-(4: aminophenyl) - N - methylamine; (c) bis - (4 -aminophenyl) diethyl siloxane, and (d) bis-(4-aminophenyl) phenyl phosphonate. Specifications 903,272 and 980,274 also are referred to.ALSO:A substrate is coated with a polyimide having the recurring group: where R is a tetravalent radical containing at least one ring of 6 carbon atoms having benzeneoid unsaturation, the four carbonyl groups being attached directly to separate carbon atoms in a ring of the R radical and each pair of carbonyl groups being attached to adjacent carbon atoms in a ring of the R radical, and R1 is a divalent benzenoid radical of the formula: where R11 is: where R111 and R1111 are alkyl or aryl groups. The polyimides are made via the corresponding polyamide-acids which may be applied in solution to the substrates and cured in situ. Specified substrates are copper, brass, aluminium or steel in the form of sheets, wires or screening; glass in the form of sheets, fibres, foams or fabrics; wood, paper; polyethylene, polypropylene, polystyrene, polyethylene terephthalate; polytetrafluoroethylene, copolymers of tetrafluoroethylene with hexafluoropropylene and polyurethanes in the form of sheets, fibres, foams, fabrics, or screening. In Example 1, glass plates are coated by casting with a polyamide-acid made from bis-(4-aminophenyl)diethyl silane and pyromellitic dianhydride, the coating being converted to polyimide by heating. Specifications 903,272 and 980,274 also are referred to.