GB1019099A - Improvements in or relating to the melt-spinning of polyamides - Google Patents

Abstract

1,019,099. Melt-spinning polyamides. SNIA VISCOSA SOC. NATURALE INDUSTRIA APPLICAZIONI VISCOSA S.p.A. March 10, 1964 [March 15, 1963], No. 10026/64. Heading B5B. In melt-spinning polyamides, the polymer chips, after having been dried, by heating in vacuo, are artificially cooled, or allowed to cool spontaneously, in an atmosphere of inert gas to a temperature not exceeding 50‹ C., and preferably between 25‹ and 30‹ C., before being transferred to the feed hopper of the melt-spinning apparatus, preferably while still surrounded by an atmosphere of the inert gas. The chips may be artificially cooled or allowed to cool spontaneously in the apparatus in which they have been dried in vacuo, a dry inert gas such as dry nitrogen having been introduced into the drying chamber until the interior of the latter is at atmospheric pressure and cold water being circulated through the jacket of the drying chamber (which may be rotated to tumble the chips) until they have been cooled to the desired temperature. Alternatively the chips may be cooled, while they are being mechanically conveyed from the drier to the melt-spinning apparatus, by contacting them with a stream of a cooled dry inert gas such as dry nitrogen. In either case the initial humidity of the inert gas may be so controlled so that it does not exceed a predetermined level, such as 70 milligrams of moisture per cubic metre of gas. In a third method the hot dry chips are discharged from the drying chamber on to a hollow horizontal metallic plate through the interior of which flows a stream of cold water. The plate is enclosed in a chamber through which flows a stream of dry nitrogen and the polymer chips are caused to travel along the entire length of the plate by vibrating the plate. The cooled chips are discharged into a duct through which they are pneumatically conveyed to the melting apparatus by a current of dry nitrogen.