Interpolyamides

Fibre-forming interpolyamides are prepared by heating hexamethylene diamine, or an amide forming derivative thereof, with a substantially equimolecular proportion of a mixture of adipic and sebacic acids containing from 68 to 90 per cent of adipic acid, or of a mixture containing corresponding proportions of amide forming derivatives of these acids, until an interpolyamide having a relative viscosity of at least 35 is produced. In a preferred procedure the interpolyamides are prepared by heating a mixture of preformed hexamethylene diamine salts of the acids containing 70.5 to 91.5 per cent of the adipic acid salt. The interpolyamides are extruded to form filaments which may be cold drawn, and which may be employed as fishing lines, sutures, and in the production of woven articles such as screens. Specifications 533,307 and 715,920 are referred to.