composite structures of linear poliimide fuse to melt the vorabile 2 2 bis (3, 4 dicarbos sifenil) esafluoropropan dinidride

摘要

1396331 Laminates E I DU PONT DE NEMOURS & CO 12 May 1972 [17 May 1971] 22420/72 Heading B5N [Also in Division C3] A process for preparing a laminate comprises curing a structure comprising a plurality of layers of a reinforcing agent impregnated with a binder solution containing a polyamide-acid or -ester obtained by reacting 2,2-bis-(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (or the reaction product thereof with water or an alcohol in amount insufficient to form the tetra-ester) with a diamine wherein RSP1/SP is -O-, -S- or -O-phenylene-O-, and which on curing is converted to a meltfabricable aromatic linear polyimide containing the unit where R is derived from an above specified diamine an n corresponds to an inherent viscosity of at least 0À15 (0À5 g./100 ml. in H 2 SO 4 ). The polyimide preferably has an I.V. at least 0À3 and a Tg of 220 to 385‹ C. The reinforcing agent may be fibres, e.g. of carbon, glass, boron or metal, or particulate, e.g. asbestos, mica, graphite, silicon carbide whiskers or P.T.F.E. The polymer may be modified by incorporating phthalic anhydride. A procedure is described in which carbon fibres are passed through a solution of the polyamide-acid or -ester, aligned in juxtaposed relationship and partially cured at about 150‹ C. to immobilize the fibres and the resulting prepreg cured at above 200‹ C. An assembly of the cured pre-pregs may then be laminated at 100 to 5000 p.s.i. and 275 to 525‹ C. Reference is made to Specification 1,071,901.