| 摘要 |
1,102,630. Polyester filaments. FARBWERKE HOECHST A.G. 29 Dec., 1965 [31 Dec., 1964], No. 55107/65. Heading B5B. A process for the uniform drawing of filaments of synthetic linear polyesters, comprises passing the filaments over rollers whose diameters increase with respect to the increasing number of filament wraps by more than 0�5%, heating the filaments on or between the rollers for 1 to 5 seconds in a state which is practically free from tension to a temperature within the range of from 80� to 150� C., and drawing the filaments in known manner. Materials specified include polyethylene terephthalate, filaments of polyesters of terephthalic acid with 1,4. dimethylol-cyclohexane or of copolyesters of terephthalic acid and isophthalic acid. In examples, the undrawn filament is first fed to an unheated step-roller 1, which is driven by a motor, passed around said step-roller as shown in Fig. 1, and then led over a flat heating element 2 to an unheated step roller 3 which is not driven. The first step of the two step-rollers 1 and 3 partially has a truncated conical shape. The filament is passed in several wraps around step-rollers 1 and 3 and over the flat heating element whereby the filament warms up and extends. The variation of the length of the filament is compensated by the increasing diameter of the conical part of step-rollers 1 and 3. After the filament has acquired the temperature of the flat heating element 2, the filament extends no further and, after the last wrap around the first step of step-rollers 1 and 3 and the flat heating element, the filament is led around a stationery heated pin 4 which has a diameter of 60 mm. around which it is passed to the extent of 1� wraps. From pin 4 the filament is led over the second step of step-rollers 1 and 3 and is drawn by these rollers which rotate at a higher peripheral speed, the filament being passed in several wraps around the second step of step-rollers 1 and 3 to prevent slipping. Preferably the increase of roller diameter with respect to the increasing number of filament wraps is between 0�5 % and 5% and especially about 2%, greater increases than 5% not being necessary in view of the extensions of polyester filaments observed within the temperature range used. Filaments so treated may be subsequently drawn in a uniform manner to less than 3�5 times, for example to twice their original length. The drawing tension also becomes more uniform so that even in the case of a high drawing rate filaments having a highly uniform dye affinity are obtained. Polyethylene terephthalate filaments of high strength are advantageously drawn at 80� to 95� C. while filaments having a high elongation are preferably drawn at 110� to 130� C. In general, filaments intended to have a strength of about 4 to 5 grams per denier, combined with elongation not exceeding 30% and a heat shrinkage at 200� C. of about 18% should be drawn at 115� to 135� C. |
