Patent GB-994321-A (GB)
Title: Process and apparatus for continuously and uniformly drawing threads of synthetic linear polymers of high molecular weight
IPC: D01F6/62
Filed: 1962-08-09
Abstract: 994,321. Synthetic filaments. FARBWERKE HOECHST A.G. Aug. 9, 1962 [Aug. 9, 1961], No. 30643/62. Heading B5B. In a process for continuously and uniformly drawing threads of synthetic linear polymers of high molecular weight which are in a glass-like state at room temperature, especially polyethylene terephthalate, the undrawn thread from a coil is wrapped several times around a uniformly driven roll and heated at 60-85 C., passed at an angle of less than 180 degrees over a rounded edge heated at 95 C.-150 C. in such a manner that it touches the heated edge over a distance of less than 15 mm. and drawnoff with or without further heating by a roll having an adjustable higher speed. Preferably the thread is heated to a temperature within the range 60-85 C. which is a few degrees below the temperature at which a jump can be observed in the drawing tension-temperature characteristic curve. The undrawn thread from a coil may be wrapped several times around a uniformly driven roll which is heated to 60- 85 C. Thus the undrawn thread may be passed several times from a stationary body heated to 60-85 C. to a uniformly driven roll. The stationary body may be a stationary roll or a stationary flat body associated with a freely running roll. Desirably, the thread is heated between the rounded heated edge and the more rapidly driven roll by a heating device having a temperature of up to 230 C. The rounded edge, which is preferably heated to 95-150 C. desirably has a surface of sintered ceramic with a high mirror finish. In the apparatus of Fig. 1, the undrawn thread 1 coming from a coil is wound several times around a heated, uniformly driven roll 2 and an associated roll 3 and then passed over a heated rounded edge 4 so that it embraces the edge with an angle of less than 180 degrees. Drawing occurs on heated edge 4 by means of roll 5 which has a higher speed of rotation than roll 2, corresponding to the desired drawing ratio. Finally, the thread is withdrawn from roll 5 and associated roll 6. In Fig. 2, the feed and draw-off rolls 2 and 5 are of different diameters and are combined on one axis. Thread 1 is wrapped several times around the heated uniformly driven roll 2 by means of associated roll 3, and is then passed with contact over rounded and heated edge 4 where it is drawn, reversed by idler roll 7, and drawn-off over roll 5 and associated roll 6. Rolls 2 and 5 have the same angular velocity and the draw-off speed of the thread is determined by the ratio of the diameter of rolls 2 and 5. In Fig. 3, the thread 1 is pressed by rubber roll 9 against an unheated feed roll 8 from which it is conducted to heated roll 2 having the same speed. By means of associated roll 3 the thread is passed several times around roll 2. It is then drawn over rounded heated edge 4 and drawn-off by roll 5 with associated roll 6. In this apparatus feed roll 8 and roll 5 are combined on one axis, and the drawing ratio of the thread is determined by the ratio of the diameters of the two rolls. In Fig. 4 the thread 1 is fed to a uniformly driven roll 2 having a temperature of 60-85 C. by means of a stationary roll 10 which is likewise heated to 60-85 C. The thread is wrapped around rolls 2 and 10 several times and then passed from stationary roll 10 at an angle of less than 180 degrees over rounded edge 4 heated at 95-150 C. The thread is then passed over idler roll 7 to roll 5 which is mounted on the same axis as roll 2 and has a higher circumferential speed determined by the ratio of the radii. The thread is passed over intermediate roll 6, by means of which it is wrapped several times around roll 5 to a winding-up device (not shown). In Fig. 5, the thread 1 is wrapped several times around a combination consisting of a uniformly driven roll 2, a stationary flat body 11 heated to 60-85 C. and an idling associated roll 12. The thread is then passed over a rounded edge 4 heated to 95-150 C. and conducted to roll 5 mounted on the same axis as roll 2, the relative circumferential speeds of rolls 2 and 5 differing according to the ratio of their radii. The thread is drawn over rounded edge 4 in proportion to said speeds, passed several times round roll 5, over roll 6 and then conducted to a winding-up device (not shown).