JPH11222711A - Spinneret for cellulose acetate yarn having specific cross section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an extrafine acetate yarn of <=4 d/f single yarn fineness having smoothness on the surface as much as possible, an improved contact feeling between the skin and cloth, a wet feeling and moist handle and its aggregate, and to provide a method for producing the yarn, by reducing a great number of complicated unevenness found in a conventional acetate yarn. SOLUTION: A cellulose acetate yarn having >=45% acetylation degree is spun by a spinneret 10 in which plural spinning holes 11 having a shape obtained by cutting off a part of a circle by one straight line 12, having an angle θmade between the two ends of the straight line 12 and the center of the circle of the equation 60 deg.<=θ<=120 deg. are circularly arranged so as to lay the parts of the straight-lines toward the center P of the spinneret. The prepared yarn has an approximately C shape of smooth peripheral surface, a cross-sectional shape of false hollow part in which both the ends are approximately bonded and <=4 d/f single yarn fineness. The cellulose acetate having a wet feeling and moist handle is obtained by making the yarn surface into a smooth surface free from unevenness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spinneret for a cellulose acetate fiber having a special cross section, and more particularly to an acetate fiber capable of imparting an unprecedented wet feeling to a fabric due to its special and novel cross section. The present invention relates to a spinneret for use.

[0002]

2. Description of the Related Art Cellulose acetate fibers have been mainly used as high-grade clothing materials which have excellent coloring properties because of their low refractive index and are dry, refreshing and have high fashionability. It is considered that the unique dry touch feeling of the acetate fiber is mainly derived from the fact that the fiber is produced by dry spinning. That is, generally, in dry spinning of acetate fibers, acetate flakes as a raw material polymer is dissolved in a highly volatile solvent such as acetone or methylene chloride to obtain a stock solution for spinning, and the stock solution is passed through a spinneret having a circular spinning hole. The solvent is discharged and the solvent in the spinning dope is evaporated and removed by the heated air to be solidified into a fibrous form.

[0003] In this dry spinning process, immediately after the spinning solution is discharged from the spinneret, the heat of the stock solution itself evaporates the solvent of the outer surface layer to form a so-called skin layer. The solvent inside the yarn evaporates due to the air. Because the volume shrinkage due to the evaporation of the solvent occurs randomly, many irregularities, usually about 4 to 12 irregularities, are formed on the fiber intricately in its cross-sectional shape,
The cross-sectional shape becomes extremely large. As a result, the fiber is considered to have a reduced contact area with human skin and the like, and a unique dry feeling and a refreshing feeling are produced.
The material is suitable for spring and summer women's clothing.

[0004] The cross-sectional shape of the fiber produced by such dry spinning is mainly determined by the shape of the spinning hole of the spinneret, the fluidity of the stock solution during solidification, and the drying speed. A spinning hole shape and a cross-sectional shape of a fiber obtained by the spinning hole have been proposed.

[0005] For example, in Japanese Patent Publication No. 37-7917,
A number of spinning hole shapes and cross-sectional shapes of fibers obtained from the spinneret are disclosed. For example, if the shape of the spinning hole is a regular triangle, a fiber having a substantially Y-shaped cross section is obtained, and if the shape of the spinning hole is a square, a fiber having a substantially X-shaped cross section is obtained. A fiber having a hollow substantially circular cross section is obtained from a 2/3 circular spinning hole, and a fiber having a hollow elliptical cross section is obtained from a crescent-shaped spinning hole. Further, in the case of a spinning hole in which three slit holes are arranged in a triangle, a fiber having a triangular cross section having a circular hollow can be obtained.

JP-B-37-12710 and JP-B-39-14012 disclose a spinning hole having a shape obtained by cutting a part of a circle by one straight line and having a diameter of 110 or 130 μm. . Further, the spinneret has a plurality of spinning holes in which the linear portion faces the same direction in a range of 1.7 to 1.7.
It is arranged in a plurality of linear rows with a hole interval of 2.0 mm, and when spinning cellulose acetate fibers using such a spinneret, by blowing hot air from one side of the linear portion of the spinning hole to one side. The cross section of the obtained fiber becomes C-shaped.

The spinning hole disclosed in Japanese Patent Application Laid-Open No. Sho 60-134012 has a substantially triangular shape in which three apexes of a triangle are cut off by a circle centered on the center of gravity of the same triangle. The spun cellulose acetate fiber has a substantially Y-shaped cross section.

Further, WO 96/35010 discloses an attempt to change the cross-sectional shape of cellulose acetate fiber by adding 5 to 40 parts by weight of a polymer substance capable of plasticizing cellulose acetate to a spinning dope. Have been. For example, when a spinning dope containing such a polymer substance is spun from a circular spinning hole, a fiber having a cocoon-shaped cross section in which the central portion of an ellipse is narrowed is obtained. When a square spinning hole is used, a fiber having a cross-shaped cross section is obtained, and when a triangular spinning hole is used, a fiber having a Y-shaped cross section is obtained.
When a fan-shaped spinning hole of 0 ° to 250 ° is used, a fiber having a substantially C-shaped cross section in which the ends are almost joined to form a pseudo hollow portion is obtained.

[0009]

With the diversification of consumer needs in recent years, acetate fibers have been required to have not only a dry feeling but also various textures and touches. In particular, acetate fibers are required to have a wet feeling and a supple drape that are completely opposite to the dry feeling of acetate fibers.

In order to provide a wet feeling, it is effective to make the fiber cross section smooth with little unevenness. In order to improve the drape property, the single fiber fineness is 4d.
It is effective to use ultrafine fibers of not more than / f. However, among the fibers disclosed in the above-mentioned publications, fibers having a cross section with large irregularities are all excellent in dry feeling, and cannot meet such demands.

[0011] Further, in the fiber having a substantially C-shaped cross section having a single pseudo-hollow portion which is close to a circle with little unevenness disclosed in International Publication WO96 / 35010, the dry feeling is reduced, As described above, the spinning hole for spinning a fiber having a U-shaped cross section is a sector of 230 ° to 250 °, and has a complicated shape in which a portion projecting at an angle toward the center of the circle is present. However, not only is it difficult to form a fine spinning hole having a diameter of 50 μm or less, but also the spinning stock solution tends to be clogged at the projecting portion, and the spinneret must be washed frequently, so that stable spinning is impossible. Becomes Therefore, it is not possible to substantially obtain an ultrafine fiber having a single fiber fineness of 4 d / f or less, and the fiber has a large fineness, so that the drape property is impaired and the wet feeling is poor.

Accordingly, the present invention reduces the cross-sectional shape of the conventional acetate fiber having many irregularities and the dry feel based on the same, and has a delicate drape property having a wet texture rich in wet feeling, which is exactly the opposite. It is an object of the present invention to provide a spinneret capable of spinning an acetate fiber. Specifically, it reduces the many intricate irregularities seen in conventional acetate fibers, has a smooth surface, and has a moist texture rich in wet feeling with improved contact feeling between skin and fibers. It is an object of the present invention to provide a spinneret for spinning ultrafine acetate fibers having a single fiber fineness of 4 d / f or less.

[0013]

Means for Solving the Problems Here, a general method for producing an acetate fiber will be described. The acetate fiber is prepared by dissolving acetate flakes in a solvent such as acetone or methylene chloride to form a spinning dope, which is then used as a circular spinning solution. It is obtained by dry spinning using a spinneret having holes. In this dry spinning, the solvent evaporates at the same time as the spinning solution is discharged from the spinneret, and the fibers harden. At this time, the outer side hardens first, forming the skin layer, and then the inner layer. As the solvent escapes, the outer skin layer partially enters the inside, and irregularities are formed on the fiber surface. When spinning is performed under normal conditions using a spinneret having the above-described circular spinning hole, the frequency of appearance of these irregularities increases, and about 4 to 12 convex portions are formed.

Based on such recognition, the present inventors have conducted intensive studies. As a result, in order to eliminate the appearance of many irregularities,
The formation speed and degree of formation of some skin layers are made different from those of other parts, and the surface is relatively low in strength and partly deformed when subjected to stress. By concentrating the strain that occurs during shrinking in that part,
It has been found that the other part can be kept relatively smooth.

Therefore, the present invention provides a method in which a plurality of spinning holes having a discharge port having a shape in which a part of a circle is cut off by one straight line are arranged in an annular shape with the straight portion facing the center of the die. The main configuration is a spinneret for special section cellulose acetate fiber.

The fiber spun from the spinneret having such a spinning hole has a cross-sectional shape immediately after spinning substantially matching the shape of the spinning hole, that is, the fiber surface is spun from the linear portion of the spinning hole. It has a flat surface and an arc surface spun from the arc portion of the spinning hole. Fiber having such a fiber surface, when the fiber surface is dried immediately after spinning, the drying speed of the flat surface is lower than the drying speed of the arc surface,
The formation of the skin layer is delayed on the flat surface than on the arc surface. Therefore, at the time of volume shrinkage due to evaporation of the solvent inside the fiber, the stress of the volume shrinkage is concentrated on a flat surface with a small degree of drying, and the flat surface is depressed toward the inside of the yarn and becomes single. Is formed, and furthermore, when the concave recess enters into the interior due to volume shrinkage, both ends thereof are almost joined to form a substantially C-shaped cross section, and a pseudo hollow portion is formed, and the peripheral surface is formed. Is a smooth surface.

In order to obtain a smooth cross-sectional shape with less irregularities, which is an object of the present invention, it is effective to arrange the linear portions in a portion where the formation speed of the skin layer is slow even with respect to the arrangement of the spinning holes. It is. In a spinneret in which a plurality of spinning holes are arranged in a ring, a solvent evaporated at the time of drying the fiber immediately after spinning is present at a high concentration at a central portion of the spinneret. And the fiber tends to be difficult to dry. Therefore, by arranging the linear portions of the plurality of spinning holes annularly toward the center direction like the spinneret of the present invention, the formation speed of the skin layer of the fiber portion discharged from the linear portions is further increased. It becomes slower, the joining portion at both ends of the concave portion becomes larger, and the peripheral surface of the fiber becomes smoother as a whole.

Conversely, when the linear portions of the plurality of spinning holes are arranged annularly outward, the skin layer forming speed of the fibers discharged from the linear portions approximates the forming speed of the other portions. There is little intrusion of the concave portion, the ends are completely separated without joining, and a pseudo hollow portion is not formed.
It becomes a character-shaped cross section. In that case, the fiber cannot be given a wet feeling, resulting in a fiber having a dry feeling.

It is preferable that the angle θ between both ends of the straight line and the center of the circle is 60 ° ≦ θ ≦ 120 °. The angle θ between both ends of the straight line and the center of the circle is larger than 120 °,
That is, when the dimension of the linear portion of the spinning hole is long, the cross-sectional area of the pseudo-hollow portion becomes large, so that the feeling of wetness is small and the feeling of bulkiness is large, and it is not preferable. Conversely, when the angle θ between the ends of the straight line and the center of the circle is smaller than 60 ° and the dimension of the straight line portion is too short, the drying speed between the flat surface and the circular arc surface of the fiber immediately after spinning is reduced. Is small and the formation of the skin layer on both surfaces is relatively uniform, so that the concentration of stress due to volume shrinkage in the linear portion as described above is eliminated, and as a result, the fiber spun through the circular spinning hole The cross section has a plurality of substantially the same irregularities.

Further, the shape of the spinning hole is extremely simple among special hole shapes for spinning a fiber having a special cross-sectional shape, and is easily formed. Therefore, it is possible to produce a spinneret having a spinning hole having a small area with a hole diameter of 50 µm or less. As a result, it is possible to spin an acetate fiber having a fineness of 4 d / f or less, and the wetness can be improved by making the fineness as described above.

Further, since the acetate fiber obtained by the spinneret of the present invention is an ultrafine multifilament of 4 d / f or less, the number of spinning holes formed in the spinneret increases. As a result, the spacing between the spinning holes arranged in a line in a ring is inevitably reduced, and the concentration of the solvent evaporated when the fiber dries also increases in the direction in which the spinning holes are arranged. Becomes low and it becomes difficult to dry. Therefore, in the spinneret, it is desirable that the interval between the spinning holes is 2.5 mm or more. This interval is 2.
If it is smaller than 5 mm, the formation speed of the skin layer in the direction of the arrangement of the spinning holes also decreases, so that stress due to volume shrinkage cannot be concentrated only on the linear portion, and a plurality of irregularities are formed on the peripheral surface, and The feeling cannot be given.
Furthermore, there is a possibility that adjacent single fibers may adhere to each other and lose product value.

Further, when dry spinning the acetate fiber, the temperature of the spinning dope when discharged from the spinneret is usually set at about 65 ° C. or more and 75 ° C. or less. However, in the present invention, by setting the temperature of the spinning solution to a range lower than the above-mentioned normal temperature, it becomes easy to obtain an acetate fiber having the above-mentioned special cross-sectional shape. That is, the temperature of the spinning dope discharged from the spinneret is 45 to 65 ° C., preferably 50 to 6 ° C.
It is preferable to set the temperature to 0 ° C. When the spinning dope temperature is 4
If the temperature is lower than 5 ° C., the solvent in the spinning dope does not dry sufficiently,
During the spinning process, a plurality of single fibers may adhere to each other or cause a yarn breakage. On the other hand, if the temperature is higher than 65 ° C., the solvent becomes extremely easy to evaporate, and even if the shape of the spinning hole is a special shape as described above, the difference in the formation rate of the skin layer between the flat surface and the arc surface of the fiber becomes small. In addition, the number of irregularities in the fiber cross section per single fiber increases.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings and representative examples. FIG. 1 is a plan view showing an arrangement of spinning holes in a spinneret of the present invention, and FIG. 2 is a plan view of the spinning holes.

The spinning hole 11 has a shape in which a part of a circle having a diameter R is cut off by one straight line 12 as shown in FIG. The angle θ formed between both ends 12a, 12a of the straight line 12 and the center O of the circle is set in the range of 60 ° ≦ θ ≦ 120 °.
Further, in the spinneret 10 having such a spinning hole 11, a plurality of the spinning holes 11 are arranged annularly with a hole interval of 2.5 mm or more with the straight line portion 12 facing the center of the spinneret P as shown in FIG. I have.

Next, the cellulose acetate fiber dry-spun using the spinneret 10 will be described with reference to examples. Note that the present invention is not limited to the following embodiments.

Various evaluations in the following Examples and Comparative Examples were measured as follows. (Hollow ratio) Cross-sectional photographs as shown in FIG. 3 and FIG. 44 were taken, and the ratio of the pseudo hollow portion to the entire cross-sectional area of the fiber was determined from the photographs, and the ratio was shown in%. (Hand) A knitted fabric was formed with a flat knitting structure using the obtained cellulose acetate fiber (multifilament), and after refining and dyeing, a sensory evaluation was performed by touch. At this time,
Comparative Example 1 was used as a standard, and those having a wet feeling were judged to be slightly good, and those having a wet feeling were judged to be good.

Comparative Example 1 Cellulose acetate flakes having an average acetylation degree of 61.2% were dissolved in a methylene chloride / methanol mixed solvent (91/9) to prepare a spinning stock solution. This spinning dope was adjusted to 72 ° C., and spinning was performed at 730 m / min with a spinneret having a circular spinning hole having a hole diameter of 38 μm, to obtain a cellulose acetate multifilament having 75 denier / 20 filaments.

Examples 1-3 and Comparative Examples 2-4 Cellulose acetate flakes having an average acetylation degree of 61.2% were dissolved in a methylene chloride / methanol mixed solvent (91/9) to prepare a spinning dope. . This spinning dope was adjusted to 60 ° C. and spun at a spinning speed of 500 m / min using a spinneret shown in Table 1 to obtain a cellulose acetate multifilament of 75 denier / 30 filaments. Table 1 shows the evaluation results of the cross-sectional shape, hollow ratio, and hand of each filament.

[0029]

[Table 1] As in Comparative Example 2, when the angle θ between both ends of the straight line of the spinning hole and the center of the circle is large and the dimension of the straight line is long, the pseudo hollow portion is formed in a state where both ends of the concave portion are separated from each other without being joined to each other. Is not formed, a concave portion having a large area is formed, and a wet feeling cannot be obtained. Further, even if the pseudo hollow portion is formed as in Comparative Example 3, if the angle θ is large and the dimension of the straight line is long, the area of the pseudo hollow portion becomes large, resulting in a hard texture. On the other hand, even when the angle θ is too small as in Comparative Example 4, a large number of irregularities are formed on the surface of the fiber, and the contact area with human skin is small, resulting in a hard feeling with a dry feeling. .

Example 4, Comparative Example 5 Average acetylation degree
2% cellulose acetate flakes were dissolved in a methylene chloride / methanol mixed solvent (91/9) to prepare a spinning dope. The spinning dope was adjusted to 57 ° C. and spun at a spinning speed of 500 m / min using a spinneret shown in Table 2 to give
A d / 30f acetate multifilament was obtained. Table 2 shows the results.

[0031]

[Table 2] As in Comparative Example 5, when a plurality of spinning holes are annularly arranged with their linear portions facing outward, stress due to volume shrinkage cannot be concentrated only on the linear portions. Until the end portions are joined to each other, the concave concave portion cannot enter the inside, a pseudo hollow portion is not formed, and a U-shaped cross-sectional shape results.

Examples 5 to 6, Comparative Example 6 Average acetylation degree 6
A 1.2% cellulose acetate flake was dissolved in a methylene chloride / methanol mixed solvent (91/9) to prepare a spinning stock solution. The spinning dope was adjusted to 57 ° C., and was dry-spun at a spinning speed of 500 m / min using a spinneret shown in Table 3 to obtain an acetate multifilament of 75d / 30f. Table 3 shows the results. FIG. 3 is a cross-sectional photograph of the fiber of Example 6, and FIG. 4 is a cross-sectional photograph of the fiber of Comparative Example 6.

[0033]

[Table 3] When the hole interval is set to 2.5 mm or less as in Comparative Example 6, the concentration of the solvent evaporated at the time of drying becomes high even at a portion in the arrangement direction of the spinning holes, and the atmosphere temperature becomes low, so that the drying becomes difficult. Therefore, as shown in FIG. 4, the fiber cross section has a plurality of irregularities formed around it. Therefore, the texture is slightly hard and a wet feeling cannot be obtained. On the other hand, in Examples 5 and 6, in which the distance between the holes was sufficiently provided to completely remove the influence of the evaporated solvent, a single pseudo hollow portion was formed in the fiber cross section as shown in FIG. Since the peripheral surface has a smooth and substantially C-shape, the fiber has an excellent wet feeling and a moist texture.

[0034]

As described above, when the fiber is spun using the spinneret of the present invention, the cellulose acetate fiber has a cross-sectional shape having a rounded overall fiber surface and an extremely smooth surface. Can be obtained, and a fabric having a wet and moist texture, which acetate fibers could not achieve before, can be provided, and its significance is extremely large.

[Brief description of the drawings]

FIG. 1 is a plan view showing an arrangement of spinning holes in a spinneret of the present invention.

FIG. 2 is a plan view of the spinning hole.

FIG. 3 is a micrograph (400-fold magnification) of a cross section of the cellulose acetate multifilament of Example 6.

FIG. 4 is a photomicrograph (400 × magnification) of a cross section of a cellulose acetate multifilament of Comparative Example 6.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Spinneret 11 Spinning hole 12 Straight line 12a Both ends of straight line O Center of circle P Center of spinneret

Claims (3)

[Claims] 1. A plurality of spinning holes having a discharge port having a shape obtained by cutting a part of a circle by one straight line, wherein the plurality of spinning holes are arranged in a ring shape with the straight part facing the center of the die. Spinneret for special section cellulose acetate fiber. 2. An angle θ between both ends of the straight line and the center of the circle.
2. The spinneret according to claim 1, wherein satisfies 60 ° ≦ θ ≦ 120 °. 3. The spinneret according to claim 1, wherein an interval between the spinning holes is 2.5 mm or more.