| 摘要 |
1,106,367. Polyarylsulphone films. IMPERIAL CHEMICAL INDUSTRIES Ltd. 26 April, 1965 [1 May, 1964], No. 18228/64. Heading B5B. An oriented film of a polyarylsulphone is formed of repeating units of the formula -Ar-SO 2 - where Ar is a divalent aromatic residue which may vary from unit to unit in the polymer chain, and in at least some of the units Ar is derived from a compound of formula (where Z is -O-, -S-, or the residue of a 4,4<SP>1</SP>-bisphenol) and in any other units Ar is similarly derived from benzene, diphenyl, or a polynuclear aromatic hydrocarbon containing not more than two aromatic nuclei so that in the divalent aromatic residues containing two benzene rings each benzene ring bears one of the valencies and one or more of the hydrogen atoms bound to aromatic rings may be replaced by halogen atoms or alkyl or alkoxy groups and a minor proportion of the -SO 2 - links may be replaced by -CO- links. The residues Ar may be derived from diphenyl ether or diphenyl sulphide, and optionally also in minor proportion from diphenyl. Films may be made by compression-moulding, melt-extrusion, calendering, or casting from a solution of the polymer in a suitable solvent e.g. nitrobenzene or dimethyl formamide. In moulding or extrusion, temperatures of at least 300‹ C. are required to obtain the material in a sufficiently mobile form, but temperatures above 330‹ C. may cause thermal degradation. Orientation may be effected by stretching, suitably at 240-260‹ C. A preferred oriented film is made from a polyarylsulphone in which the benzene rings in the polymer chain are essentially all -para. The stretching method used depends largely on the process used for forming the film. Longitudinal stretching may be effected by the use of feed and draw rolls, and the film may then be transversely stretched by tentering. Alternatively tentering alone may be employed using a tenter in which the pairs of clamps diverge laterally while the distance between adjacent pairs is also increased, thus simultaneously stretching the film both laterally and longitudinally. Alternatively, tubular films may be made by melt-extrusion and drawn by passage between two pairs of nip rolls while simultaneously inflated, in known manner. |
