GB1309501A - Polyamideimide compositions - Google Patents

Abstract

1309501 Polyamide-imide films TORAY INDUSTRIES 19 April 1971 [3 Feb 1970(2)] 21517/71 Heading B5B [Also in Division C3] A film-forming composition comprises (a) a polyamide-imide having a repeating unit of the general formula (II) (b) an organic solvent therefor; and (c) a phosphorus compound providing 0À00015 to 6À5% P by weight of the polymer. In the formulµ R 1 , R 3 and R 5 represent divalent organic groups, R 3 differing from R 5 and R 2 and R 4 are respectively tri- and tetra-valent organic groups having one and two pairs of carbonyl groups in cylic anhydride-forming positions. The polymers (a) preferably have an inherent viscosity above 0À4 and may be prepared by first reacting the appropriate tri- or tetra-carbonyl compound with an amino-acid H 2 N-R 1 -COOH or diamine H 2 N-R 5 -NH 2 in proportions giving a COOH terminated product which is then reacted with a diisocyanate OCN-R 3 -NCO. A large number of polymer-forming reactants, solvents and phosphorus compounds, both organic and inorganic, are specified. Making films.-The compositions are used to make films by being extruded or poured on to a plate, belt or drum and dried thereon. The phosphorous compound is stated to reduce adhesion thus enabling this technique to be used with these normally lightly adhesive polymers. The polymer in the film-forming composition may be incompletely imidized, depending on the temperature of formation of the carboxyl-terminated intermediate, imidization being completed after separation of the polymer. Examples illustrate film formation on various metal plates, belts or drums, e.g. of steel, stainless steel or chromium. Subsequent heat treatment, e.g. at 300‹ C. for 30 mins. may be effected to improve heat resistance, chemical resistance and electrical insulating properties of the film.