| 摘要 |
1,254,924. Polyester yarn. SOC. RHODIACETA. 18 March, 1969 [18 March, 1968], No. 14297/69. Heading B5B. [Also in Division D1] A multifilament yarn of polyester material in which each filament has on the microscopic scale, alternating thick and thin parts is further characterized in that the thick parts, on the microscopic scale, comprise alternating zones of at least two different average diameters, the zones of smallest diameter having the highest crystallinity and molecular orientation and vice versa. The thin parts, on the microscopic scale, comprise either the same alternations of zones and the same differences of structural characteristics to a much lower degree, or are substantially uniform in diameter. The thick parts have a non-spiral 3-dimensional crimp and are bulked. The least crystalline zones of the thick parts have a crystallinity index below 20%. A process for producing the yarn comprises partially stretching at a stretch ratio of 1À5-3À5 a multifilament yarn of a polyester material in contact with a crack-promoting agent, e.g. ethanol, heat treating the yarn in a relaxed state, and continuously or intermittently varying the degree of relaxation during such heat treatment and/or the degree of stretching during the initial or a supplementary partial stretching treatment. In one embodiment of the process, a supplementary partial stretch in which the degree of stretch varies precedes a heat treatment in a relaxed state. In an alternative embodiment, the yarn may be stretched to a varying degree while in contact with a crack-promoting agent. The polyester material is preferably polyethylene terephthalate. Apparatus for carrying out the method comprises means e.g. rollers 5, 6 for feeding yarn 3 to a bath 7 of crack-producing agent, means e.g. draw rollers 8, 9 for stretching the yarn in the bath, means 10 for heating the yarns, means e.g. rollers 11, 12 for relaxing the yarn while it is heated, means e.g. reciprocating finger 15 for intermittently or continuously changing the degree of relaxation during such heat treatment and/or the degree of stretch during the initial or a supplementary stretching treatment, and means 16 for winding up the yarn produced. The finger 15 may form part of, or be carried or operated by, a cam driven by a motor. In alternative embodiments of the apparatus, the finger 15 is disposed between the relaxing rollers 11, 12 and the wind up means 16, or between the feed rollers 8, 9 and the heater 10. |
