GB1298413A - Process for melt spinning - Google Patents

Abstract

1298413 Spinning apparatus IMPERIAL CHEMICAL INDUSTRIES Ltd 4 Aug 1971 [4 Aug 1970] 37582/70 Heading B5B Spinning apparatus comprises a spinning pack 1 and a spinneret 2 with a face exposed to ambient atmosphere and associated in close proximity to, or contiguity therewith, a shield 7, disposed parallel to said face of substantially the same size and shape as the exposed spinneret face, and through an aperture or apertures in which shield the extruded filaments pass, so that in the melt-spinning of fibre-forming polymers through a plurality of such spinning packs, variation between the rates of loss of heat from the exposed faces of the various spinnerets is minimized, since at least the faces of said shields directed towards said exposed spinneret faces are maintained at substantially constant and substantially identical temperatures as a result of being supplied with a source of heat in common with that serving to maintain the spinnerets at the desired temperature. The source of heat is suitably a heattransfer fluid. Thus spinning pack 1 is heated by vapour jacket 3, and the pack and vapour jacket are insulated by a muff 4, an insulating lid 5 and insulation 6. The shield temperature should differ from that of the heat transfer medium by not more than 50‹ C, especially no more than 10‹ C. The shield is suitably constructed of material of high thermal conductivity e.g. copper, aluminium or silver, and may be movable or removable to permit wiping of the spinneret face. That face of the shield directed towards the spinneret face may be polished, and is suitably chrome plated. The other side of the shield 8 may be provided with a layer of low thermal conductivity e.g. asbestos, or a chamber containing air or which is evacuated. A shield may be in more than one part. Thus, where the pattern of spinneret holes constitutes a straight line the shield may be in two parts one each side of the straight line, the two parts of the shield delineating a narrow band free from shielding and in which the spinneret holes are situated. Figure 2 shows a view from below the spinneret of Fig. 1.