Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1991-05-23
1993-07-13
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
264237, B29C 4788, B29C 7100
Patent
active
052271102
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a method for the production of highly oriented amorphous polyester filament yarns by means of melt spinning with winding speeds of >4000 m/min, as well as an apparatus for the implementation of the method.
BACKGROUND OF THE INVENTION
The production of a fast spun polyester filament yarn consisting of at least 85 weight % of ethyleneterephthalate units, leads to a feeder-yarn which, because of its highly oriented amorphous qualities, is eminently suitable for false twist texturing. However, these properties can only be obtained if fast cooling can be effected at high winding up speeds.
Basically, two different methods were proposed to obtain such a shock cooling process.
Thus EP-A-O 089 819 describes a shock cooling process by means of water. In this process, a polyethyleneterephthalate filament yarn is cooled in a water bath at a rate of at least 5000 m/min. While being highly oriented, the resultant yarn only has a low crystallinity, substantiated by a boiling shrinkage of at least 45% and at most 68.5%.
However, cooling in water has serious drawbacks. First of all, the yarn is subjected to breaking in the water bath, resulting in high stresses. There occur problems with spraying water and the application of a spinning preparation onto the wet yarn. When using water cooling, there occurs a rapid increase in the water carried along adhering to the surface, and hence in the spraying water, as the number of filaments increases.
As compared with shock cooling with water, an improvement has been obtained with air cooling. Thus EP-A-O 244 216 describes a polyester filament yarn which is spun at a rate of over 5000 m/min in a high pressure chamber where a narrow tube is arranged at its outlet, shock cooling being obtained because of the Venturi effect. In the case of air cooling, the uniform cooling of the gathered filament bundle in the cooling tube (Venturi) is no longer ensured as the number of filaments increases.
Apart from the drawback of the high specific air consumption of up to approximately 70 Nm.sup.3 /kg of polyethyleneterephthalate, it is not possible to ensure a defined yarn speed in the range below the spinneret, exactly at the point where the most intensive cooling must be effected.
Objects of the Invention
It is the object of the invention to provide a method for the shock cooling of a fast spun polyethyleneterephthalate filament yarn, which ensures a defined yarn speed in the cooling range.
A further object is to make available an apparatus for implementing the above mentioned method.
Another object is to make available a polyester filament yarn with a high birefringence and a relatively high boiling shrinkage as a feeder yarn.
Other objects and advantages of the invention will become apparent as the description thereof proceeds.
DESCRIPTION OF THE INVENTION
The solution of the problem lies in a method which, is characterized in that the melt spun filament yarns are cooled by means of a rotating contact surface, and that they are subsequently provided with a spinning preparation and wound up.
A rotating contact surface has the advantage that an operation becomes possible under more defined conditions without a liquid or gaseous medium. Irrespectively thereof, it is possible to determine the cooling rate by determining the distance of the cooling surface from the spinneret and the angle of contact of the yarn on the cooling surface.
Merely by varying the two parameters, it is possible to obtain a great number of yarn properties.
It has proved to be expedient to choose the contact times of the filament yarn on the contact surface between 1.times.10.sup.-3 and 1.times.10.sup.-2 s, in particular 2.times.10.sup.-3 -6.times.10.sup.-3 s, set with a range of the peripheral speed of the contact surface between 1600 to 2400 m/min. It is, of course, also possible to calculate the contact length or the angle of contact of the filament yarn from the specification of the time.
The polyester yarn produced in accordance with the method, surprisingly ha
REFERENCES:
patent: 2322976 (1943-06-01), Schmitz
patent: 3553305 (1971-01-01), Au
patent: 3832435 (1974-08-01), Bauer et al.
patent: 4244907 (1981-01-01), Wu
patent: 4743504 (1988-05-01), Carr
Baris Halim
Fischer Klaus
Tentoni Leo B.
Viscosuisse S.A.
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