Core-sheath conjugated fiber, slit fiber, and method of manufacturing such fibers

Patent metadata

Field	Value
Publication number	US-10745829-B2
Application number	US-201615549890-A
Country	US
Kind code	B2
Filing date	Feb 3, 2016
Priority date	Feb 13, 2015
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

A core-sheath conjugated fiber includes two kinds of polymer, wherein the core-sheath conjugated fiber is characterized in that the core component has projected shapes having projections and grooves alternately in a cross section in a direction perpendicular to the fiber axis, the projections are formed continuously in the direction of the fiber axis, and the height (H) of the projections, the width (WA) at the tip of the projections, and the width (WB) of the bottom surface satisfy the formulas at the same time:

1.0≤ H /( WA ) 1/2 ≤3.0  (1)

0.7≤ WB/WA ≤3.0  (2).

First claim

The invention claimed is:

1. A slit fiber prepared by removing a sheath component from a core-sheath conjugated fiber; the core-sheath conjugated fiber comprising two kinds of polymer,
wherein
the core-sheath conjugated fiber is characterized in that a core component has projected shapes having projections and grooves alternately in a cross section in a direction perpendicular to a fiber axis, projections are formed continuously in a direction of the fiber axis, and a height (H) of the projections, a width (WA) at a tip of the projections, and a width (WB) of a bottom surface and a distance (PA) between the adjacent projection tips satisfy formulae (1), (2) and (3) at the same time:
1.0≤ H /( WA ) 1/2 ≤3.0 . . .   (1)

1.0≤ WB/WA ≤3.0. . .   (2)

0.1≤ WA/PA ≤0.5. . .   (3);

and
an area proportion of the core component is at least 70% and up to 90% in the cross section perpendicular to the fiber axis of the core-sheath conjugated fiber, and
the slit fiber having slits which are continuous in the direction of the fiber axis; and
wherein the height (H) of the projections, the width (WA) at the tip of the projections, and the width (WB) of the bottom surface and the distance (PA) between the adjacent projection tips being measured in the following procedure:
a multifilament comprising a core-sheath conjugated fiber is embedded in an embedding agent and a cross section of the embedded core-sheath conjugated fiber is observed by using a scanning electron microscope (SEM) at a magnification capable of observing at least ten projections protruding from the core component into the sheath component to thereby obtain a two-dimensional picture and ten random projections in a picture are measured for their projection height (H), width of the tip (WA), width of the bottom surface (WB) and the distance (PA) between the adjacent projection tips is a distance between the intersecting points of the center line and the circumcircle of the adjacent two projections by the unit of μm, and measurements were rounded to a first decimal place, and the procedure was repeated for ten pictures and values were averaged and rounded to a first decimal place.

2. A slit fiber having projected shapes having projections and grooves alternately in a cross section in a direction perpendicular to a fiber axis, projections are continuously formed in a direction of the fiber axis, and a height (HT) of the projections, a width (WAT) at a tip of the projections, a width (WBT) of a bottom surface, a slit width (WC) and a fiber diameter (DC) of the slit fiber satisfy the formulae at the same time:
1.0≤ HT /( WAT ) 1/2 ≤3.0  (4)

0.7≤ WBT/WAT ≤3.0  (5)

0.02 WC/DC ≤0.10  (6);

wherein the height (HT) of the projections, the width (WAT) at the tip of the projections, and the width (WBT) of the bottom surface are measured in the following procedure:
the projection height (HT), width at the tip (WAT), and width of the bottom surface (WBT) of the projection are measured by embedding a multifilament comprising the slit fibers in an embedding agent and observing a cross section of the embedded slit fibers by using a scanning electron microscope (SEM) at a magnification capable of observing at least ten projections to thereby obtain a two-dimensional picture and ten random projections in the picture were measured for their projection height (HT), width at the tip (WAT), and width of the bottom surface (WBT) by the unit of μm, and the measurements were rounded to a first decimal place and the procedure was repeated for ten pictures and values were averaged and rounded to a first decimal place; and
the slit width (WC) and the fiber diameter (DC) of the slit fiber is measured in the following procedure:
the slit width (WC) is determined by taking an image of a cross section of the slit fiber with a scanning electron microscope (SEM) at a magnification allowing observation of at least ten slits and the slit width (WC) is a value measured by a difference of a distance between adjacent projection tips and a width of the projection tip using ten random slits from the image, and when at least ten slits cannot be observed in one slit fiber, at least ten slits in total are observed by including slits of another slit fiber, the slit width is measured at a unit of μm, a value measured is rounded to the first decimal place, and the procedure is repeated for ten images and values were averaged and rounded to a first decimal place; and
the fiber diameter (DC) of the slit fiber is a diameter of a perfect circle which contacts a cross section at two or more points in the cross section of the slit fiber in a direction perpendicular to the fiber axis in a two-dimensional image, the fiber diameter (DC) being measured by embedding a bundle of the slit fibers in an embedding agent, slicing the embedded slit fibers, taking images of the cross section with a stereomicroscope at a magnification capable of observing ten or more fibers, randomly choosing ten fibers in an image, measuring the circumcircle of the fibers in the unit of μm, rounding the measurement to a first decimal place, repeating the procedure for ten images, and calculating a simple number average of a fiber diameter (DC) value measured in each image and its ratio (WC/DC).

3. The slit fiber according to claim 2 , wherein the projections are so formed that a distance between adjacent projection tips (slit width WC) in the cross-section perpendicular to the fiber axis has a variation (CV %) of at least 1.0% and up to 20.0%.

4. The slit fiber according to claim 2 , wherein degree of irregularity of the cross-sectional shape in the direction perpendicular to the fiber axis is 1.0 to 2.0.

5. The slit fiber according to claim 2 , wherein the fiber contains a polyamide as its main component.

6. The slit fiber according to claim 3 , wherein degree of irregularity of the cross-sectional shape in the direction perpendicular to the fiber axis is 1.0 to 2.0.

Assignees

• Toray Industries

Inventors

• Masuda Masato
• Matsuura Tomohiko
• Kanemori Yasunori

Classifications

• D01F6/60

  from polyamides (from polyamino acids or polypeptides D01F6/68) · CPC title

• D10B2401/06

  Load-responsive characteristics · CPC title

• D01F8/12

  with at least one polyamide as constituent · CPC title

• D01F1/02

  Addition of substances to the spinning solution or to the melt (addition of substances to viscose D01F2/08) · CPC title

• D01D5/34

  Core-skin structure; Spinnerette packs therefor · CPC title