GB1237004A - Polymer films - Google Patents

Abstract

1,237,004. Polyimide films. TORAY INDUSTRIES Inc. 3 Dec., 1968 [4 Dec., 1967; 15 March, 1968 (2)], No. 57205/68. Heading B5B. [Also in Division C3] A linear polymer having a repeating unit where R 1 is a tetravalent aromatic group with the valencies (1) ortho to (2) and (3) ortho to (4); R 2 is a C 3+ trivalent group with the valencies (5) and (7) on carbons adjacent to those carrying valencies (6) and (8) respectively; R 3 is a C 2+ bivalent group; X is -OR, -SR, -COOR or -NHR; and R is H or a C 1-6 hydrocarbon radical, is cast into a film and then heated first at a temperature between the primary and secondary transition points and thereafter at temperature between the secondary transition point and decomposition temperature to give a linear polymer having the repeat unit The film may be immersed in an acetic acidpyridine solution prior to the first heating which is preferably effected for 0À5 to 10 minutes at 100‹ to 250‹ C. with the film under tension. The second heating may be effected under reduced pressure or inert gas at 300‹ to 450‹ C. preferably till at least 20% cyclization is effected. The cast film may contain 20 to 50 wt. per cent residual solvent prior to the first heating. Numerous examples are given of polymerforming reactants, solvents, diluents and solubility-promoting inorganic salts and organic bases. The initial polymer preferably has an inherent viscosity of 0À3 to 3. Additives such as Al, Fe, Sn and Zn halides may be compounded with the film.