Patent GB-1294751-A (GB)
Title: Process for the production of a shaped article of a heat resistant polymer
IPC: C08G73/00
Filed: 1970-04-23
Abstract: 1294751 Heat-resistant polymer films and fibres TORAY INDUSTRIES Inc 23 April 1970 [24 April 1969 16 Dec 1969 21 Jan 1970] 19447/70 Heading B5B [Also in Division C3] A film, sheet, or fibre of a heat-resistant polymer is made by (1) extruding a composition (C) of: (A) a polymer containing heterocyclic rings (H), and (B) an organic solvent for polymer (A), at a temperature T e  above the softening point, so as to retain the cross-sectional shape imparted on extrusion; and (2) heat-treating the extruded article at a temperature T h , where T h  > Te. There is 15-150% wt. solvent (B) based on polymer. (A) may also contain groups (G) convertible to heterocyclic groups on heating. Heterocycles (H) form 15-100% of (H+G). The heat-treatment removes remaining solvent (B) and cyclizes (G). (H) may be imide, imidazole, benzoxazole, benzimidazole, benzoxazinone, imidazopyrrolone, hydantoin, oxathiadiazole, and/or oxadiazole rings. Composition (C) is solid at or below room temperature; it may have softening point < 270‹ C. T h  may be 200-500‹ C. The extruded article may be cooled to 30-350‹C. below T e  before heattreatment; or it may be heat-treated in the molten state; or it may be contacted with a compound which is miscible with solvent (B), liquid at room temperature, and a non-solvent for (A) before heat-treatment. Solvent (B) may have b.p. # 150‹ C. (A) may be formed in the appropriate amount of (B), or in excess (B), the excess being removed after polymerization. Composition (C) may be in particle or pellet form, or used directly after polymerization without solidifying. The article may be a film, sheet, or fibre. Exemplified starting materials for polymer (A) include: butane-1,2,3,4-tetracarboxylic acid, trimellitic anhydride, 3,3<SP>1</SP>,4,4<SP>1</SP>- benzophenonetetracarboxylicdianhydride, pyromellitic anhydride, pyromellitic dianhydride, trimellitic acid chloride, isophthalic acid chloride, diphenyl ether dicarboxylic acid dichloride, isophthalic acid dihydrazide p-aminobenzoic acid, 4 - amino - 4<SP>1 </SP>- carboxybiphenylketone, 1 - amino - 4 - carboxycyclohexane, 4,4<SP>1 </SP>- diaminodiphenylmethane, N,N<SP>1</SP> - diethoxycarbonyl - 4,41 - diaminodiphenylmethane, 4,41- diaminodiphenyl ether, 4,4<SP>1</SP>-isopropylidene-bis- (2 - aminophenol), 5 - amino - 2 - (m - aminophenyl) - benzoxazole, diphenylmethane diisocyanate, and p-phenylene diisocyanate. In examples: (1) a film is extruded at 180‹ C. and placed on a metal belt heated to 200‹ C., the film being heat-treated successively at 200‹, 250‹, and 300‹ C. (2) A film is extruded from a die at 195‹ C., and then heated with hot air, heated to 250‹ C. to remove solvent, and then heated to 300‹ C. under tension. (3) Filaments are melt-spun at 190‹ C., air-cooled, and then wound around a heated roller and heat-treated at 300‹ C. (4) A film is extruded from a die at 170‹ C., and wound round a metal drum at 20‹ C. to solidify it. It is then heated by radiant heat on both surfaces to 280-300‹ C. (5) A film extruded at 150‹ C. is similarly cooled to 20‹ C. and is then heat-treated at 280‹ C. (6) A film is extruded through a die at 170‹ C. to a film which is solidified, and then treated in hot air at 100‹ C. (7) A film extruded from a die at 150‹ C. is wound round a drum at 10‹ C., and is then treated with hot air at 200‹ C., and is then heattreated at 280‹ C. under tension. (8) A film extruded from a die at 150‹ C. is contacted with a metal belt in an inert atmosphere at 280‹ C. (9) A film extruded through a die at 175‹ C. is cooled on a drum to 20‹ C. and is then heated to 330‹ C. by air containing < 10% O 2 , its edges being held by clips. (10) A film is extruded from a die at 170‹ C. and heat-treated under tension at 280‹ C. (11) A film is extruded from a die at 160-180‹ C., dipped into a water-bath at 30‹ C., contacted with a metal belt, cooled to room temperature, peeled from the belt, and heat-treated successively at 200‹, 250‹ and 300‹ C. Other examples describe similar methods to these, different temperatures being sometimes employed.