JPH0790720A - Hollow acrylic yarn and production thereof - Google Patents

Abstract

PURPOSE:To obtain hollow acrylic yarn suitable for clothing use, having excellent physical properties of fiber, productivity and water absorption properties and provide production thereof. CONSTITUTION:This hollow acrylic yarn has a hollow part substantially continuing in the direction of fiber axis and intermittent cracks on an outer wall wherein the cracking reach from the surface of the yarn to the hollow part, the length of the cracks in the direction of fiber axis is >=1mu and the width of the cracking in the direction of the cross section of fiber is <=0.5mu. In subjecting two kinds of acrylonitrile-based polymers containing >=0.1wt.% of different copolymer components or two kinds of acrylonitrile-based polymers having >=0.5wt.% of difference in content of the same copolymer component and using one of the acrylonitrile-based polymers as a sheath component and the other as a core component, the yarn is obtained by making the solution concentration of the core component at least three wt.% lower than that of the sheath component.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a hollow acrylic fiber which is excellent in fiber physical properties, productivity and water absorption and suitable for clothing applications,
And a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, many attempts have been made to give an acrylic fiber a hollow structure for the purpose of improving heat retention and bulkiness and water absorption.
No. 1-28014, Japanese Patent Laid-Open No. 61-29611, Japanese Patent Publication No. 60-18332, Japanese Patent Laid-Open No. 3-249.
It is proposed in Japanese Patent No. 215, etc. But these are
It was intended to absorb water from the hollow cross section of the short fiber, and it was not considered to absorb water from the surface, and it did not have sufficient water absorption for the purpose of using it as long fibers. . Further, as a method for increasing the water absorption from the surface of the fiber, an attempt to form a small hole extending from the surface to the hollow portion in the wall of the hollow fiber is also disclosed.
Although it is proposed in Japanese Patent Publication No. 4-68415, it requires a new operation such as mixing a foreign substance into the sheath and then removing it, which is not only disadvantageous in productivity and spinning stability, but also deteriorates fiber physical properties. There were problems such as easy occurrence.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, the object of the present invention is to provide a hollow acrylic fiber which is excellent in water absorbency without causing deterioration in fiber physical properties and productivity, and also as long fibers, and It is to provide the manufacturing method.

[0004]

The first gist of the present invention is as follows.
An acrylic fiber having a hollow portion which is substantially continuous in the fiber axis direction and which has a large number of intermittent cracks on the outer wall, and the cracks reach the hollow portion from the fiber surface, and the fiber axis direction of the cracks. The hollow acrylic fiber has a length of 1 μm or more and a width of the crack in the fiber cross-sectional direction is 0.5 μm or less.

A second gist of the present invention is that two kinds of acrylonitrile-based polymers containing different copolymer components in an amount of 0.1% by weight or more, or the same copolymer component in an amount of 0.5% by weight. % Of the two acrylonitrile-based polymers differing by at least 2% from the sheath component and the other from the core component, the solution concentration of the core component is at least 3% by weight less than that of the sheath component. Using the composite spinning dope, the cross-sectional shape of the undiluted solution at the portion where the spinning dope is discharged from the spinneret has a portion in which the sheath component is thinly formed around the core component, and the core component Characterized in that the hollow portion is formed by three-dimensionally complex core-sheath composite spinning and cascade drawing so that the thickness of the thinned portion is 3 times or more in the surroundings so that the thickness of the thinned portion becomes half or less of the thickness of the thickest portion. Hollow Acry It is a method for producing a fiber.

First, the hollow acrylic fiber which is the first gist of the present invention will be described in detail. The fiber of the present invention needs to be an acrylic fiber having a hollow portion that is substantially continuous in the fiber axis direction, and absorbs moisture in the hollow portion to develop water absorption. This hollow portion needs to be continuous without being divided in the fiber axis direction. The cross-sectional shape of the hollow portion is not particularly limited, but if the structure has an eccentric structure, defects in the physical properties of the fiber are likely to occur, which is not preferable.

The fiber of the present invention has a length of 1 μm or more in the fiber axial direction and a width of 0.5 μm or less in the fiber cross-sectional direction, and has a large number of intermittent cracks extending from the fiber surface to the hollow portion. Must be on the outer wall. Due to this crack,
Even long fibers can absorb water from the surface of the fibers, resulting in hollow acrylic fibers having excellent water absorption that could not be achieved by conventional techniques. That is, the water adhering to the fiber surface through such cracks is supplied to the hollow portion, whereby the hollow acrylic fiber excellent in water absorption, which is the object of the present invention, can be obtained. The size of the cracks has a great influence on the water absorption, and the smaller the capillary phenomenon, the better the water absorption resistance, and the larger the water absorption resistance, the better the fiber axial direction length is 1 μm or more. Is preferably 0.5 μ or less. In terms of the physical properties of the fiber, if the width exceeds 0.5 μ in the cross-sectional direction of the fiber, the physical properties of the fiber are significantly deteriorated, which is not preferable.

Next, a method for producing hollow acrylic fibers, which is the second aspect of the present invention, will be described. In the present invention, in order to obtain a hollow structure, the sheath component and the core component contain different copolymerization components in an amount of 0.1% by weight or more, or in the case of containing only the same copolymerization component, the copolymerization component It is necessary that the contents have a difference of 0.5% by weight or more. When the core-sheath copolymer does not meet the above conditions, peeling between the two components does not occur during the production process, and the hollow structure intended by the present invention cannot be obtained. Further, the concentration of the polymer solution of the core component needs to be at least 3% by weight or more lower than the concentration of the polymer solution of the sheath component. When the concentration of the core-sheath component does not meet the above conditions, the hollow ratio becomes low, and the hollow structure of the present invention cannot be sufficiently achieved.

Further, in order to cause a large number of intermittent cracks in the outer wall, when performing the core-sheath type composite spinning, the sheath thickness should be at least three points at substantially equal intervals on the circumference of the cross section. It is necessary to spin so that it is less than half of the thickest part of the sheath. By partially reducing the thickness of the sheath,
In the process after the spinning process, it is possible to cause a crack to naturally occur in the sheath portion from the fiber surface to the hollow portion. In addition, in order to cause cracks in any direction on the fiber surface, the thin portions must be at least at three locations on the circumference of the cross section at substantially equal intervals. The thickness of the sheath needs to be appropriately set depending on the manufacturing conditions. Generally, if the difference between the thick and thin portions of the sheath is not more than twice, it is possible to selectively cause cracks in the thin portion. It is impossible. As a method for obtaining a modified core-sheath type composite fiber having such a cross-sectional shape, for example, Japanese Patent Application No. 5-4
This is achieved by using the spinneret described in Japanese Patent No. 3577.

A typical manufacturing method of the present invention using such a spinneret will be described with reference to the drawings. FIG. 1 shows a vertical cross-sectional view of a composite spinneret, and FIG. 2 shows AA in FIG.
It is sectional drawing of a line.

In the illustrated embodiment, the spinneret is composed of first and second spinnerets 1 and 2 which are arranged in a tatami mated state, and a core component polymer supply hole 3 is provided at the center of the first spinneret 1. A sheath component polymer supply hole 4 is formed so as to be formed so as to penetrate through the line and be parallel to the core component supply hole 3 at a position apart from the core component supply hole 3 of the first die member 1. There is.

A funnel-shaped spinning passage 8 is formed in the center of the second die member 2 and communicates with the core component supply hole 3 with the same diameter, and is gradually tapered from the middle thereof. Also, the second
Around the inlet of the core component polymer of the die material 2, a groove-shaped sheath component liquid reservoir 5 is formed continuously on the concentric circumference of the inlet, and between the sheath component liquid reservoir 5 and the inlet. Three or more (in this embodiment, six at equal intervals) independent sheath component flow paths 6 that communicate radially are formed. Therefore, the inlet portion of the core component polymer constitutes the core / sheath component combining passage 7 which joins with the sheath component polymer.

In the illustrated example, the six sheath component flow paths 6 are branched from the ring-shaped sheath component liquid reservoir 5 at equal intervals and extend in the centripetal direction as shown in FIGS. Although they are merged at a right angle to the flow direction of the sheath component flow path 7,
The sheath component flow channel 6 is merged in the tangential direction of the inlet circumferential surface of the core-sheath component flow channel 7, or separately, by being inclined downward at a predetermined angle in the flow direction of the core-sheath component flow channel 7. Sometimes.

It should be noted that the sheath component liquid reservoir 5 enables uniform pressure supply to the sheath component flow passages 6, and when the cross-sectional areas of the respective sheath component flow passages 6 are matched, If the resistance is uniform, a uniform coating shape of the sheath component can be obtained. Also,
As a matter of course, if the cross-sectional area of the sheath component flow path 6 is changed, a modified coating shape can be obtained.

Using the spinneret of the present invention constructed as described above, the liquid polymer of the core component is supplied from the core component supply hole 3 provided at the center of the spinneret and separated from the core component supply hole 3. The liquid polymer of the sheath component is supplied to the sheath component supply hole 4 at the above position. The liquid polymer of the core component introduced into the core component supply hole 3 flows down the spinning passage 8 as it is through the core / sheath component mixing passage 7, but one sheath component supply hole 4
The liquid polymer introduced into the core is temporarily stored in the sheath component liquid reservoir 5, and then passes through each sheath component flow passage 6 to form the core-sheath component combined flow passage 7
Sent to.

A core-sheath component joint flow path 7 is passed through each sheath component flow path 6.
The liquid polymer of the sheath component sent to the
Is melted and integrated independently around the liquid polymer of the core component flowing down, and when it passes through the funnel-shaped spinning path 8, it is spun into a linear shape having the cross-sectional shape shown in FIG.

The spinning method in the present invention is not particularly limited, and any of wet, dry and dry-wet spinning methods which are generally used for the production of acrylonitrile fiber can be used and may be selected according to the purpose. You can choose As the polymer in the present invention, polyacrylonitrile or acrylonitrile, various vinyl monomers and copolymers can be used. Examples of vinyl-based monomers include vinyl acetate, vinylidene chloride, acrylamide, methyl methacrylate, acrylic acid, methyl acrylate, vinyl bromide, sodium methacryl sulfonate, and the like.

As the solvent used in the present invention, those generally used as a solvent for an acrylonitrile polymer can be used, and examples thereof include dimethylacetamide, dimethylformamide, γ-butyrolactan, ethylene carbonate, sodium thiocyanate nitrate, and chloride. A zinc aqueous solution and the like can be mentioned.

The present invention will be described below with reference to examples.

【Example】

[Example 1] Acrylonitrile 91%, vinyl acetate 9%
A dimethylacetamide solution containing 24% by weight of a copolymer containing a is a sheath component, and a 20% dimethylacetamide solution of a copolymer containing 89% acrylonitrile and 11% vinyl acetate is a core component. 3/1,
Using the modified core-sheath type composite spinneret shown in FIGS. 1 and 2, dry-wet spinning was carried out so that the cross-sectional shape of the yarn in the coagulation bath became the shape shown in FIG. 3, and a fiber having a fineness of 3d was obtained. . As the coagulation bath, a 60% by weight aqueous solution of dimethylacetamide was used at 50 ° C., and the cascade stretching ratio was set to 5 times. The fiber thus obtained is a fiber having a cross-section and a side shape as shown in FIGS. 4 and 5. Further, the obtained fiber is used to make a merias fabric and absorb water (JISL1018 sedimentation method). When it was examined, it was 2.5 seconds.

EXAMPLE 2 A 24% by weight dimethylacetamide solution of a copolymer containing 91% acrylonitrile and 9% vinyl acetate was used as a sheath component, and acrylonitrile 90 was used.
20% dimethylacetamide solution of a copolymer containing 10% by weight, vinyl acetate 9%, and sodium methacrylsulfonate 0.5% by weight as a core component, and the core / sheath discharge ratio is 3 /.
1 and using the modified core-sheath type composite spinneret shown in FIGS. 1 and 2, dry-wet spinning is performed so that the cross-sectional shape of the yarn in the coagulation bath becomes the shape shown in FIG. Got
The coagulation bath is an aqueous solution of dimethyl acetamide 60 wt% 5
It was used at 0 ° C. and the cascade stretch ratio was set to 5 times. The fiber thus obtained is a fiber having a cross-section and a side shape as shown in FIGS. 4 and 5. Further, the obtained fiber is used to make a merias fabric and absorb water (JISL1018 sedimentation method). Was examined, it was 2.7 seconds.

Comparative Example 1 Acrylonitrile 89 was prepared by using a 24% by weight dimethylacetamide solution of a copolymer containing 91% acrylonitrile and 9% vinyl acetate as a sheath component.
%, A 20% dimethylacetamide solution of a copolymer containing 11% vinyl acetate as a core component, a sheath / core discharge amount ratio of 3/1, and a concentric circular core-sheath composite nozzle, which is used for coagulation bath yarn. Dry-wet spinning was performed so that the cross-sectional shape of the strip became a shape as shown in FIG. 6, and a fiber having a fineness of 3d was obtained. The coagulation bath uses a 60% by weight aqueous solution of dimethylacetamide at 50 ° C.
The cascade draw ratio was 5 times. The fiber thus obtained is a fiber having a cross-sectional shape and a side surface shape as shown in FIGS. 7 and 8. Further, the fiber thus obtained is used to make a merias fabric and absorb water (JISL1018 sedimentation method). Was examined and found to be 5.5 seconds.

[0022]

INDUSTRIAL APPLICABILITY The hollow acrylic fiber of the present invention has excellent water absorption because it enhances the water absorption due to the cracks on the surface of the fiber as well as the formation of the hollow part, and the heat retention property originally possessed by the hollow fiber structure, It is a fiber that has excellent bulkiness and is particularly suitable for clothing applications. Further, the fiber of the present invention has fiber physical properties (strength, etc.)
It is also an excellent hollow acrylic fiber. Further, the method for producing a hollow acrylic fiber of the present invention does not require a complicated step of forming pores on the fiber surface in a subsequent step, does not cause a decrease in productivity, and, even as a long fiber, absorbs water. A hollow acrylic fiber having excellent properties can be provided.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a composite spinneret of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view showing a fiber cross section immediately after spinning obtained by the production method of the present invention.

FIG. 4 is a cross-sectional view showing a cross section of a fiber obtained by the production method of the present invention after coagulation and stretching.

FIG. 5 is a perspective view showing a side surface of a fiber obtained by the production method of the present invention after coagulation and stretching.

FIG. 6 is a cross-sectional view showing a cross section of a fiber obtained in Comparative Example 1 immediately after spinning.

FIG. 7 is a cross-sectional view showing a fiber cross-section obtained in Comparative Example 1 after coagulation and stretching.

8 is a perspective view showing a side surface of a fiber obtained in Comparative Example 1 after coagulation and stretching. FIG.

[Explanation of symbols]

 1 Upper Mouth Metal Material 2 Lower Mouth Metal Material 3 Core Component Supply Channel 4 Sheath Component Supply Channel 5 Sheath Component Liquid Reservoir 6 Sheath Component Channel 7 Core-Sheath Component Combined Channel 8 Spinning Channel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Hayashi 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A hollow portion which is substantially continuous in the fiber axis direction and has intermittent cracks in the outer wall, the cracks extending from the fiber surface to the hollow portion, and in the fiber axis direction of the cracks. A hollow acrylic fiber having a length of 1 μm or more and a width of the crack in a fiber cross-sectional direction of 0.5 μm or less. 2. Two kinds of acrylonitrile-based polymers containing 0.1% by weight or more of different copolymer components, or two acrylonitrile-based polymers containing 0.5% by weight or more of the same copolymer component. One of the coalesces is the sheath component,
When composite spinning is performed using the other as the core component, a composite spinning dope is used in which the solution concentration of the core component is at least 3% by weight lower than the solution concentration of the sheath component, and the spinning dope is discharged from the spinneret. The cross-sectional shape of the undiluted solution has a portion in which the sheath component is thinly formed around the core component, and at three or more portions around the core component, the thinnest portion is the thickest portion. 2. The method for producing a hollow acrylic fiber according to claim 1, wherein the hollow core is formed by subjecting the modified core-sheath composite spinning to a half or less of the thickness and performing the cascade drawing.