Stretched poly(arylene thioether-ketone) films and production process thereof

Claim 1

A process for the production of a stretched poly(arylene thioether-ketone) film which comprises processing a thermoplastic material into the stretched poly(arylene thioether-ketone) film, wherein said thermoplastic material comprising: (A) 100 parts by weight of a melt-stable poly(arylene thioether-ketone) having predominant recurring units of the formula ##STR7## wherein the --CO-- and --S-- are in the para position to each other, and having the following physical properties (a)-(c): (a) melting point, Tm being 310°-380° C.; (b) residual melt crystallization enthalpy, ΔHmc (420° C./10 min) being at least 10 J/g, and melt crystallization temperature, Tmc (420° C./10 min) being at least 210° C., wherein ΔHmc (420° C./10 min) and Tmc (420° C./10 min) are determined by a differential scanning calorimeter at a cooling rate of 10° C./min, after the poly(arylene thioether-ketone) is held at 50° C. for 5 minutes in an inert gas atmosphere, heated to 420° C. at a rate of 75° C./min and then held for 10 minutes at 420° C.; and (c) reduced viscosity being 0.3-2 dl/g as determined by viscosity measurement at 25° C. and a polymer concentration of 0.5 g/dl in 98 percent by weight sulfuric acid; and optionally, (B) up to 100 parts by weight of at least one of thermoplastic resins and/or up to 15 parts by weight of at least one of fillers, wherein upon processing the thermoplastic material into the stretched poly(arylene thioether-ketone) film, the thermoplastic material is formed into an amorphous film, the amorphous film is stretched, as first-stage stretching, to a draw ratio of from 1.5:1 to 7:1 in one direction at 100°-180° C. to give a birefringence of 0.05-0.35, the resultant film is stretched, a optional second-stage stretching, to a draw ratio of from 1.5:1 to 7:1 in a direction perpendicular to said one direction at 100°-180° C., and the resulting film is then heat set at a temperature of from 200° C. to a temperature just below the melting point of the poly(arylene thioether-ketone).