Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1989-06-08
1992-04-21
Lesmes, George F.
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, D02G 300
Patent
active
051066858
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the manufacture of a cold drawn, flat polyester filament yarn made of POY with an intrinsic viscosity of 0.6 to 0.9 dl/g as well as a polyester filament yarn manufactured according to the process.
A flat multiple filament yarn is not a textured filament yarn which retain his uncurled flat form even after the boiling in water.
Polyester is a thermoplast made from at least 85 weight percent terephtalic acid and ethylene glycol.
Polyester-POY (Partially Oriented Yarn) stands for a polyester yarn which was drawn, i.e. spun, from the spinning nozzle at a speed of appr. 2,500 to 3,500 m/min. The winding can be performed directly by means of a spooler or a pair of rolls can be interposed. The pair of rolls turns at the same or at a slightly lower speed than the spooler which serves to control the yarn tension in order to improve the winding structure. The exact spinning speed for a good POY depends on different spinning conditions, in particular on the fibril titer. For example, a fibril titer of 1 dtex should be used for the lower limit and a fibril titer of 10 dtex applies more to the upper limit.
Cold drawing signifies a drawing at yarn temperatures which are significantly below the glass conversion temperature of polyester, that is significantly below 85.degree. C. For example, in order to perform a drawing the feeding roll can either be not heated or have a temperature up to 70.degree. C.
A homogenous cold-drawing is to imply that the draw-ratio must be selected so high as to avoid undrawn or insufficiently drawn parts in the drawn yarn, i.e. drawn under the draw ratio selected, which can be recognized from the Uster % which should be less than 1.4. For POY of the speed range indicated, this means, according to the spinning speed, the draw ratio must be at least 1.8.
Hot relaxation means a length decrease of the yarn caused by a heat treatment involving temperatures above the glass conversion temperatures. The amount of length decrease is determined by what is referred to as the overfeed [VE]: ##EQU1##
The percentage of shrinkage or relaxation [S] is related to the overfeed as follows: ##EQU2## VE=overfeed V.sub.L =Speed of feeding rolls
It is known to manufacture cold-drawn polyester yarns from POY which is spun with more than 3,500 m/min (JP-A-53-14 37 28).
Conventionally known, drawn yarns made of polyester-POY have the disadvantage that a flat structure made thereof is not thermostable during a tension-free or yarn-tension-free treatment in boiling water or hot air. This undesirable property during further manufacture, i.e. after a tension-free, thermal treatment, is indicated by a pronounced relaxation shoulder in the force-elongation-diagram.
It is the object of the invention to provide a process for manufacturing a polyester filament yarn which does not exhibit these disadvantages and moreover, has a high initial modulus, high strength and a low shrinkage.
The object is achieved in accordance with the invention in that the POY is cold-drawn at a constant draw ratio between 1.8 and 2.5 and subsequently relaxed at a constant overfeed between 3 and 10%.
The invention will be best understood from the following description of the drawings wherein:
FIG. 1 shows a schematic block-diagram of the process according to the invention;
FIG. 2 shows strength-elongation curves of polyester yarns, PES dtex 70 f 24, in accordance with the present invention;
FIG. 3 shows strength-elongation curves of polyester yarns, PES dtex 90 f 24, in accordance with the present invention; and
FIG. 4 shows strength-elongation curves of polyester yarns, PES dtex 150 f 30, in accordance with the present invention.
Surprisingly, thermal influences caused only slight dimensional changes. After the hot water treatment, a relatively high initial modulus is retained. This was the first time to succeed in manufacturing a dimensionally stable, high-strength filament yarn from polyester by employing a polyester-POY, using an intrinsic viscosity of 0.6 to 0.9 dl/g obtained through cold drawing, followed b
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.
patent: 4950539 (1990-08-01), Specker et al.
Lesmes George F.
Rhone-Poulenc Viscosuisse SA
Withers James D.
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