| 摘要 |
1,151,723. Removal of monomer from polyamides. FARBENFABRIKEN BAYER A.G. 19 May, 1966 [21 May, 1965], No. 22285/66. Heading C3R. Monomeric and oligomeric materials are removed from a high M.W. polyamide by passing it in molten form into a heated tube which is under vacuum and in which a screw conveys it along the internal wall of the tube to the outlet point, the central portion of the tube remaining free to permit monomeric and oligomeric material to distil off and be discharged. Polyamides specified include polycaprolactam, copolyamides, e.g. a condensate of caprolactam and hexamethylene diammonium terephthalate, polyesteramides and copolyamide/polyureas. They may be of 2À5-4À0 reduced viscosity. The temperature of the tube may vary along its length, e,g. it may rise from inlet to outlet. It may be between 220‹ and 320‹ C. The pressure in the tube may be 0À001-10 mm. Hg. The tube may be at any inclination, e.g. vertical or horizontal. An additive may be introduced into the melt during distillation, e.g. a concentrate of TiO 2 in the polyamide. In a particular embodiment (Fig. 1) the polyamide melt enters at 4, the monomeric and oligomeric material is drawn off at 8 and the polymer discharged by gear pump 6. In another embodiment (Fig. 2, not shown) the vapour outlet 8 is next to 4 and the treated polymer is discharged by a second screw which is conical in shape and the axis of which is an extension of the axis of the main screw. |
