| 摘要 |
1277814 Electrically insulating polyesters DYNAMIT NOBEL AG 20 June 1969 [21 June 1968] 31441/69 Heading C3R A thermostable electrical insulating foil, film, coating or material for impregnating bodies comprises a polyester having the general Formula I in which n is an integer between 80 and 300 and R represents a radical of the Formula II wherein q and r are integers between 1 and 3, the sum of q and r being 4, and A is a direct chemical bond, an aliphatic radical, a sulphonyl group or an oxygen atom, in which polyester 20 to 99% of the acid units are derived from isophthalic acid, the remainder being derived from terephthalic acid. The polyesters may be prepared by reacting mixtures of terephthalic and isophthalic acid dichlorides with chlorinated bis-phenols, the preferred bis-phenols being bis-(3,5-dichloro-4- hydroxyphenyl)-alkanes such as 2,2-bis-(3,5- dichloro-4-hydroxyphenyl)-propane. The bisphenol may be partially replaced by 1-40 mol. per cent of a chlorinated monocyclic phenol to give groups R of the Formula IV: wherein q<SP>1</SP> is an integer of 1 to 4, preferably by a chlorinated hydroquinone, such as tetrachlorohydroquinone. |
