Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,...
Reexamination Certificate
2002-01-10
2003-09-16
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Reexamination Certificate
active
06620502
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polytrimethylene terephthalate fiber suitable for the high-speed draw false-twist texturing process and a method for producing the same. More specifically, the present invention relates to a partially oriented polytrimethylene terephthalate fiber capable of being subjected to the draw false-twist texturing process, in a stable manner and for a long period, and a method for production thereof.
BACKGROUND ART
A fiber using polytrimethylene terephthalate (hereinafter referred to as PTT) obtained from the polycondensation of terephthalic acid or a lower alcoholic ester of terephthalic acid; typically dimethyl terephthalate; with trimethylene glycol (1,3-propanediol) is an epoch-making fiber having properties similar to polyamide, such as a low elastic modulus (soft touch), excellent elastic recovery and a good dyeability as well as properties similar to polyethylene terephthalate (hereinafter referred to as PET), such as those excellent in resistance to light, heat settability and dimensional stability and a low water-absorption, and used for a BCF carpet, a brush, a tennis racket string or others (for example, see the U.S. Pat. Nos. 3,584,108 and 3,681,188, J. Polymer Science; Polymer Physics (Vol. 14, pages 263 to 274, Published in 1976), Chemical Fibers International (Vol. 45, pages 110 to 111, Published in April 1995), and Japanese Unexamined Patent Publication (Kokai) Nos. 9-3724, 8-173244 and 5-262862).
One of fibrous aspects in which the above-mentioned properties of PTT are maximally exhibited is a false-twist textured yarn. The false-twist textured yarn of PTT is excellent in elastic recovery and softness in comparison with the conventional false-twist textured yarn of PET or polybutylene terephthalate (hereinafter referred to as PBT) and is extremely suitable for a raw yarn of a stretchable material, as disclosed in Japanese Unexamined Patent Publication (kokai) Nos. 9-78373 and 11-093026.
When the PTT false-twist textured yarn is used while applying the above-mentioned properties thereof to various fields in which PET or polyamide fiber have been conventionally used, it is very important to facilitate the productivity of the PTT false-twist textured yarn and reduce the production cost thereof. However, since a drawn yarn produced through a two-stage process including the spinning and the drawing is used as a raw yarn to be subjected to the false-twist texturing process in such prior arts as disclosed in the above Publications, the productivity becomes lower to increase the production cost of the fiber. Also, since the drawn yarn is used as a raw yarn, it is impossible to apply thereto a draw false-twist texturing process which can be carried out at a high speed and a high productivity.
To facilitate the productivity and reduce the production cost, it is desirable to use a fiber produced through a single stage process similar to PET fiber or polyamide fiber and carry out the draw false-twist texturing at a high speed.
A technology for carrying out the draw false-twist texturing of PTT fiber produced through a single stage process is disclosed in Chemical Fibers International (Vol. 47, pages 72 to 74, published in February 1997) wherein a partially oriented yarn (hereinafter referred to as POY) of PTT is subjected to a draw false-twist texturing process. More specifically, PTT polymer having an intrinsic viscosity [&eegr;] of 0.9 is extruded at a temperature in a range from 250 to 275° C., cooled and solidified, and after being imparted with a finishing agent, taken up as POY of PTT (hereinafter referred to as PTT-POY) via a godet roll or no godet roll at a speed in a range from 600 to 3200 m/min, which is then subjected to a false-twist texturing process at a speed in a range from 450 to 1100 m/min.
Also, in Korean Unexamined Patent Publication No. 98049300, there is a description of a method for producing PTT-POY by spinning a polymer having an intrinsic viscosity in a range from 0.75 to 1.1 at a spinning speed in a range from 2500 to 5500 m/min and a technology for false-twist texturing this PTT-POY at a temperature in a range from 150 to 160° C. and at a processing speed of 400 m/min. In Japanese Unexamined Patent Publication (Kokai) No. 57-193534, there is a description of PTT-POY obtained by spinning a polymer having an intrinsic viscosity [&eegr;] of 0.97 at a spinning speed in a range from 2500 to 3000 m/min.
According to a study made by the present inventors, however, the PTT-POYs described in the above documents or Patent Publications have a drawback in that the yarn largely shrinks on a bobbin on which it is wound so as to tighten the bobbin, and if an amount of the yarn corresponding to that of PET fiber usually adopted in an industrial scale is wound, the bobbin largely deforms to prevent a cheese-shaped package from being removed from a spindle of a winder. Under the circumstances, even if the deformation of the bobbin could be mitigated by using a bobbin of a large mechanical strength, there would be a so-called bulge phenomenon in which opposite lateral sides of the package are swollen outward, or the yarn would be tightly wound in the inner layers. Accordingly, a yarn tension becomes higher and fluctuates largely when the yarn is unwound, and fluff and/or yarn breakage frequently occur during the draw false-twist texturing process, as well as irregularities of crimping or dying may be generated.
A technology for fixing a fibrous structure is disclosed in Japanese Examined Patent Publication (Kokoku) No. 63-42007, wherein a polymer prepared by blending PET with PTT and/or PBT is melted and extruded, which, after being cooled and solidified, is heat-treated by a hot roller and taken up at a speed of 3500 m/min or higher to result in a fiber having an elongation at break of 60% or lower and a shrinkage in boiling water of 7% or lower.
In this Publication, another fiber is disclosed as a comparative example, obtained from PTT homopolymer, and a polymer prepared by blending 10 wt % of PET with PTT homopolymer which is then heated at 180° C. in the same manner as the above and taken up at a speed of 4000 m/min to have an elongation at break of 33% and a shrinkage in boiling water of approximately 4%. Also in this Publication, a high speed spinning in which the fiber is heated by a roller and PTT fiber obtained thereby are described. However, the technology disclosed in this Publication is one for suppressing the shrinkage by facilitating the crystallization of the resultant fiber when the fiber is used for clothing as it is so that the crepability is improved.
According to the study made by the present inventors, if the fiber is heat-treated at a temperature as high as 180° C. or more, the bulge or collapse of yarn coils in the package may frequently occur. Also, since such a fiber is heat-treated at a high temperature to have a low elongation at break of 60% or lower which is similar to that of the drawn fiber, it is impossible to carry out the draw false-twist texturing of the fiber.
Regarding the polyamide type POY, Japanese Unexamined Patent Publication (Kokai) No. 50-71921 discloses the technology for obtaining a package free from the collapse of yarn coils by heat-treating the fiber with a hot roller. If the polyamide POY is not crystallized, it is liable to extend due to moisture absorption to cause the collapse of yarn coils. The technology disclosed in this Publication is to solve such a collapse of yarn coils.
In Japanese Unexamined Patent Publication (Kokai) No. 51-47114, a technology is disclosed wherein a fiber spun at a high speed is heat-treated under a tense state through a hot roller to crystallize the same, whereby the elongation at break of the fiber is lowered and the ease of false-twisting the fiber is improved. The technology disclosed in this Publication, however, aims to lower the elongation at break of the fiber and improve the crimpability thereof.
In other words, the technologies disclosed in both the Publications aim to achieve objects different from the improvem
Fujimoto Katsuhiro
Kato Jinichiro
Asahi Kasei Kabushiki Kaisha
Edwards N.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
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