Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1988-06-09
1990-08-21
Lowe, James
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
2642108, 2642896, 2642905, D02J 122, D01D 512
Patent
active
049505394
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of producing a smooth, cold-drawn, multifilament yarn from polyester POY (partially oriented yarn) and to a yarn produced by this process.
A smooth multifilament yarn is to be understood as meaning an untextured multifilament yarn which retains its uncrimped flat shape even on boiling in water.
Polyester is to be understood as meaning a thermoplastic material prepared from at least 85% by weight of terephthalic acid and ethylene glycol.
Polyester POY refers to a polyester yarn which has a linear density of about 50 to 1,200 dtex and was melt-spun at a speed of about 2,800 to 4,000 m/min.
In the present invention, cold drawing refers to drawing at yarn temperatures which are significantly below the glass transition temperature of the polyester, i.e. appreciably below 85.degree. C. For example, a delivery roller for the drawing can be unheated or be at a temperature of up to 70.degree. C. The drawing can take place with or without the use of a drawing peg.
Homogeneous cold drawing is to be understood as meaning that the draw ratio has to be chosen sufficiently high to ensure that, in the drawn yarn, there are no undrawn areas or areas drawn to less than the draw ratio, which is discernable for example in the Uster %, which in general should be <1.5. For POY from the stated speed range, this means that the draw ratio shall be at least 1.6, depending on a spin speed.
For the purposes of the present invention, hot relaxation is a treatment which causes a decrease in the length of the yarn by heat treatment at temperatures above the glass transition temperature. The extent of the decrease in length is determined by the overfeed VE: ##EQU1## V.sub.L =speed of delivery system V.sub.A =speed of take-off system
The production of a cold-drawn polyester yarn from POY spun at more than 4,000 m/min is known from (JP-A-53-143,728).
DE-A-2,839,672 discloses a polyester replacement yarn for cellulose acetate, having a boil shrinkage of 2 to 6% and obtainable by direct high-speed spinning at about 4,000 m/min without the use of a drawing system or any heat treatment. In this publication, a boil shrinkage of less than 2% is referred to as extremely low and as very difficult to obtain directly.
The main disadvantage of the known yarn consists in that its shrinkage is still too high. In addition, such a yarn has to be shrunk before package dyeing and be rewound onto perforated dyeing centers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process whereby it is possible to prepare a yarn which has an extremely low shrinkage while resembling a cellulose acetate or viscose yarn in-its other properties.
This object is achieved according to the invention by a method of producing a polyester yarn which is characterized in that the polyester POY, in a first process step, is homogeneously cold-drawn to a draw ratio of at least 1.6 and, in a second process step, is hot-relaxed under an overfeed of 10 to 20%.
In the range from 10 to 20% overfeed, preferably from 12 to 18% overfeed, with simultaneous heat treatment, the product is surprisingly a virtually shrinkage-free yarn which produces a full-bodied, soft sheetlike structure which has good drape and a silky lustre in the case of undelustred polymer.
The resulting yarn is highly suitable for use as a replacement material for cellulose acetate in smooth sheetlike structures and exhibits high utility for napping.
If the overfeed is less than 10%, the result is a yarn having an excessively high shrinkage; an overfeed of more than about 20% gives rise to a form of crimping which is undesirable for the intered use as a smooth yarn.
It is expedient to carry out the dry heat treatment at 140.degree. to 250.degree. C., preferably at 200.degree. to 230.degree. C., in particular at 225.degree. C., combined with a heater length of at least 200 mm.
However, it is also possible to carry out the heat treatment in a fluid, advantageously in water/steam, at 70.degree. to 140.degree. C.
It is e
REFERENCES:
patent: 3651198 (1972-03-01), Mitsuishi et al.
patent: 3770866 (1973-11-01), Sakata et al.
patent: 3816486 (1974-06-01), Vail
patent: 4195052 (1980-03-01), Davis et al.
Lieferprogramm, Viscosuisse, Switzerland, (no translation).
Industrial Aspects of High Speed Spinning, Kawaguchi, Historical Review.
Textilveredlung, Die wichtigsten Chemiefasern, Erweiterter Sonderdruck, 1972, (no translation).
Schaffner Paul
Specker Hugo
Lowe James
Striker Michael J.
Viscosuisse SA
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