Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2002-11-04
2004-11-30
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S395000, C206S392000
Reexamination Certificate
active
06824869
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polyester type conjugate fiber package obtained by a single-stage melt-spinning method, a method for producing the same and a false-twist texturing method thereof.
BACKGROUND ART
Polyethylene terephthalate (hereinafter referred to as PET) fiber has been mass-produced throughout the world, to establish a large industry, because it is most suitable for the clothing use.
Polytrimethylene terephthalate (hereinafter referred to as PTT) fiber is known from prior art documents such as J. Polymer Science: Polymer Physics Edition: Vol. 14, p 263 to 274 (1976), Japanese Unexamined Patent Publication (Kokai) No. 52-5320 or WO-99/27168.
There is a disclosure in these prior art documents in that a fabric using PTT fibers having a proper elongation at break, thermal stress and/or shrinkage in boiling water has a low modulus to exhibit a soft hand touch and is suitable for the clothing such as inner wear, outer wear, sportswear, hosiery, lining cloth or swim suits.
On the other hand, polyester conjugate fibers of a side-by-side type or an eccentric sheath/core type have been known as fibers capable of providing a fabric with a bulkiness without being subjected to a false-twist texturing process.
As a PTT type conjugate fiber characterized by a soft hand touch, there is a conjugate fiber in which PTT is used as at least one of its components or a conjugate fiber in which PTTs having different inherent viscosities are used as both components (hereinafter, these are referred to as polyester type conjugate fibers), as disclosed in Japanese Examined Patent Publication (Kokoku) No. 43-19108, Japanese Unexamined Patent Publication (Kokai) Nos. 11-189923, 2000-239927, 2001-55634, EP 1059372, Japanese Unexamined Patent Publication No. 2001-131837, U.S. Pat. No. 6,306,499, WO 01/53573 or US 2002-0025433. These prior art documents describe that the polyester type conjugate fiber is characterized by a soft hand touch and a favorable crimp developing property which characteristics are suitable for various stretch fabrics or bulky fabrics.
In general, when the polyester type conjugate fiber is produced by a melt spinning method, there are a two-stage method in which an undrawn fiber once wound as a package is drawn to be a drawn fiber and a single-stage method in which the spinning and the drawing are continuously carried out in one process.
In Japanese Unexamined Patent Publication (Kokai) Nos. 2001-131837, 2001-348734 and 2002-61031, a so-called direct spin-draw method is proposed when the polyester type conjugate fiber is produced, in which the spinning and the drawing are continuously carried out in one stage.
Particularly, in Japanese Unexamined Patent Publication No. 2001-131837, a polyester type drawn conjugate fiber is disclosed, which has a stretching elongation of 10% or more even under a load of 3.5×10
−3
cN/dtex by controlling a thermal shrinkage stress thereof to be 0.25 cN/dtex or more. This polyester type drawn conjugate fiber can be hard-twisted and used for a woven fabric having a large structural-constraint force, in which fabric the fiber develops a high crimpability.
Methods for obtaining a pre-oriented fiber to be false-twisted are disclosed in Chemical Fibers International: Vol. 47. p72 to 74 (February, 1997), and Japanese Unexamined Patent Publication (Kokai) Nos. 2001-20136 and 2000-256918. In these documents, as a pre-oriented fiber to be false-twisted, a fiber consisting solely of PTT or a polyester type conjugate fiber is disclosed, which is wound at a speed of 2000 to 6000 m/min without using a godet roll or with a cold godet roll.
According to the study of the present inventors, the polyester type pre-oriented conjugate fiber or drawn conjugate fiber obtained at a high spinning speed has a high orientation degree but a low crystallinity. Such a pre-oriented conjugate fiber or drawn conjugate fiber has a glass transition temperature in a range from approximately 35 to 45° C. and is extremely sensitive to temperature and humidity.
In a spinning process, there is a phenomenon in that the heat generation of a motor of a winder running at a high speed is transmitted to a package via a bobbin shaft to increase the package temperature. Also, the package temperature rises by the heat generated due to the friction between the package and a presser roll. It has been also apparent that, if the package temperature is increased by such causes, the pre-oriented conjugate fiber or drawn conjugate fiber shrinks in the package during the winding.
The shrinkage of the pre-oriented conjugate fiber or drawn conjugate fiber hardly occurs in package-selvage portions (hereinafter referred merely to as selvage portions) in which the fiber is layered to have a high winding hardness, but solely occurs in the fiber layered in the remaining portion (hereinafter referred to as a central portion). As a result, the package is of a high-selvage shape during the winding. Once the high-selvage shape is formed, the selvage portion is alone in contact with the presser roll and the frictional heat is further concentrated to the selvage portion as a winding weight of the package increases.
The resultant package thus wound to have a predetermined diameter is of a so-called high-selvage shape wherein a (winding) diameter of the selvage portion is larger than that of the central portion.
FIG. 1
is a schematic illustration of a package in a non-high-selvage shape, and
FIG. 2
is a schematic illustration of a package in a high-selvage shape.
The high-selvage shaped package not only has a difference in diameter but also has a large difference in fiber property as described later, such as a thermal characteristic, yarn fineness and the number of crimps, between the selvage portion and the central portion.
In addition, as a winding weight increases, a lateral end surface of the package tends to be bulged outward due to the fiber shrinkage to form a so-called bulge whereby it is impossible to remove the package from the winder.
(i) Difference in Dry Heat Shrinkage Stress Value
The polyester type conjugate fibers in the selvage portion and the central portion of the package are different from each other in dry shrinkage stress value obtained by the measurement of the heat shrinkage stress described later. That is, the dry heat shrinkage stress value of the conjugate fiber in the selvage portion is higher than that of the conjugate fiber in the central portion.
It has been apparent that the difference in heat shrinkage characteristic becomes apparent as a difference in shrinkage or crimpability of a fabric during the dyeing process to cause a drawback of appearance quality such as a tight yarn or a puckering.
(ii) Variation in Yarn Fineness
The variation in yarn fineness of the pre-oriented conjugate fiber or drawn conjugate fiber is a periodic variation corresponding to a fiber length from one of the selvage portions of the package to the other (1 stroke or 2 strokes).
Charts measuring the variation in yarn fineness of the pre-oriented conjugate fiber or drawn conjugate fiber unwound from the package by an evenness tester are shown in
FIGS. 3 and 4
.
FIG. 3
is a chart corresponding to the package of FIG.
1
and
FIG. 4
is a chart corresponding to the package of FIG.
2
. In the measurement charts, the periodic variation is observed by downward pin-like signals appearing at an equal pitch on a lower yarn fineness side. The existence of the downward signal means that a yarn fineness of the fiber (yarn thickness) at this point in the fiber length direction fluctuates to the smaller side.
It has been apparent that such a variation in yarn fineness causes a periodic dyeing unevenness in a false-twist textured yarn or a fabric.
(iii) Apparent Crimp
The polyester type conjugate fiber is characterized to have a latent crimpability capable of developing the crimp after the heat treatment. However, there may be a case in which the crimp has already been developed while the fiber is maintained as being wound in the package. This is the apparent crimp.
As the appa
Abe Takao
Koyanagi Tadashi
Asahi Kasei Fibers Corporation
Edwards N.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
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