JP3506926B2 - Special cross-section cellulose acetate yarn and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cellulose acetate yarn having a special cross-sectional shape and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, cellulose acetate yarn has been
It has excellent color development and is positioned as a highly fashionable clothing material that is dry and has a refreshing feel. It is believed that the unique dry feel of the acetate yarn is derived mainly from the fact that the cellulose acetate fiber is produced by dry spinning. That is, generally, in dry spinning of cellulose acetate fiber, cellulose acetate flakes, which is a raw material polymer, is dissolved in a highly volatile solvent such as acetone or methylene chloride to prepare a spinning stock solution, and the spinning stock solution is discharged from a spinneret and heated. A method is adopted in which the solvent in the spinning dope is evaporated and removed by air to solidify into a fibrous form.

In this dry spinning process, immediately after the spinning dope is discharged from the spinneret, the heat of the dope itself evaporates the solvent on the outer surface layer of the extrudate to form a so-called skin layer. The heated air evaporates the solvent inside the discharge. Volumetric shrinkage occurs in the fibrous material solidified with the evaporation of the solvent, but the volumetric shrinkage is not uniform because the evaporation of the solvent progresses with the formation of the skin layer, so that the fiber cross section becomes uneven. In the case of using a spinneret having a mixed shape and a circular spinning hole, about 4 to 12 irregularities are usually formed as shown in FIG. As a result, the cellulose acetate yarn having the textured fiber surface exhibits a unique dry feeling and refreshing feeling.

The fiber surface condition of the cellulose acetate yarn 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 evaporation rate of the solvent. The larger the number of concave portions on the surface, the greater the internal scattering reflection with respect to the light entering from the outside, and the more the apparent gloss of the yarn tends to decrease. In particular, when the monofilament fineness of the yarn is reduced, the scattering reflection increases with respect to the incidence of light as the whole yarn, and the decrease in the apparent gloss of the yarn is promoted.

As a method for improving the gloss of fibers, it is generally effective to use a polymer having a high refractive index, but cellulose acetate has a refractive index of 1.48.
However, since it belongs to the category of low refractive index, and it is difficult to improve the gloss of the cellulose acetate fiber by the polymer itself, it is considered effective to make the fiber cross-section irregular, and also in the cellulose acetate fiber. Various proposals have been made for a spinning hole shape and a modified cross-section fiber. For example, JP-B-37-7917 and JP-A-60
No. 134012, WO0096 / 35010, and the like have proposed a modified cross-section fiber such as a Y-shaped cross section, a cross section, an elliptical cross section, a hollow triangular cross section, a cocoon-shaped cross section, and a C-shaped cross section.

However, according to such a proposal, the obtained cellulose acetate fiber is excellent in dry feeling, but is insufficient in gloss feeling, or in the case of a fiber having a convex smooth surface in the fiber cross section, There is an improvement in gloss,
The gloss anisotropy was strong, giving the textile a feeling of irritability and reducing the dry feeling.

[0007]

SUMMARY OF THE INVENTION In the present invention, since the dry feeling and gloss of the cellulose acetate yarn depend on the formation speed and the formation of the skin layer in the dry spinning, the formation of the skin layer in the dry spinning of the cellulose acetate yarn. By controlling the speed and the degree of formation, a part of the surface of the discharge product that is easily deformed and a part that is difficult to deform when subjected to volume contraction stress are formed, and the volume contraction of the discharge product is partially concentrated. Therefore, the results of the study on the shape and arrangement of the spinning holes of the spinneret have been completed. An object of the present invention is to provide a special cross-section cellulose acetate yarn having an excellent dry feeling and an extremely improved gloss.

[0008]

The present invention has a degree of acetylation of 48.
5% or more of cellulose acetate yarn, the fiber cross section of which has a substantially triangular shape, which extends from the substantially central portion of one side toward the center of the fiber cross section, and the side end is opened or closed in a slit shape. A special cross-section cellulose acetate yarn having a pseudo hollow portion in the fiber cross section and the pseudo hollow portion area occupying 2 to 10% of the total cross sectional area, and the degree of acetylation 48.
When dry spinning 5% or more of cellulose acetate, the spinning hole is a shape in which a regular square is divided into four regular squares and one small regular square is omitted. A method for producing a cellulose acetate yarn with a special cross-section, which comprises using a spinneret in which a missing portion is arranged in an annular shape with the spinneret centered.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The cellulose acetate yarn having a special cross section of the present invention is composed of cellulose acetate having a degree of acetylation of 48.5% or more, and its fiber cross section has a substantially triangular shape as shown in FIG. In the fiber cross section, there is an end at the substantially central part of one side of the substantially triangular shape, and it spreads out in the center direction of the fiber cross section, and the end on the side is opened in a slit shape or its slit-shaped opening. It has a spindle-shaped or drop-shaped pseudo-hollow portion that is closed due to the close contact.

The special cross-section cellulose acetate yarn of the present invention is a cellulose acetate yarn in which the area of the fiber cross section of the pseudo hollow portion accounts for 2 to 10% of the total cross-sectional area, that is, the hollow ratio is 2 to 10%. Further, in the special cross-section cellulose acetate yarn of the present invention, one side of the fiber cross section having a substantially triangular shape has an end portion of a pseudo hollow portion, which gives a dry feeling.
As shown in Fig. 2, the other two sides of the fiber cross section having a substantially triangular shape form a smooth concave curve, and the ratio A of the maximum length (A) to the depth (B) of the recess on each of the two sides is A. / B is 100 / 0-1
It is in the range of 00/15. Therefore, the special cross-section cellulose acetate yarn fiber of the present invention has less scattered reflection on the concave surface with respect to the incident light and more condensed reflection, thereby significantly improving the gloss. FIG. 5 shows a photograph of a fiber cross section of an example of the cellulose acetate yarn of the special cross section of the present invention.

The special cross-section cellulose acetate yarn of the present invention can be produced, for example, by the method described below. That is, when dry-spinning cellulose acetate having a degree of acetylation of 48.5% or more, the spinning hole has a shape in which a regular square is divided into four regular squares and one small regular square is omitted. The special cross-section cellulose acetate yarn of the present invention can be manufactured by using a spinneret in which a plurality of spinning holes are arranged in an annular shape with the missing portions facing the center of the spinneret.

As a general method for dry spinning cellulose acetate in the production of cellulose acetate yarn, cellulose acetate flakes having an acetylation degree of 48.5% or more are dissolved in a solvent such as acetone or methylene chloride to have a concentration of 15 to 30. As a spinning dope of 10% by weight, the spinning solution was spun into heated air at 70 to 120 ° C. from a spinneret in which spinning holes were arranged.
A method in which the solvent in the spinning dope is evaporated to solidify the cellulose acetate is used.

In the method of the present invention, during such dry spinning of cellulose acetate, as the spinneret, as shown in FIG. 3, the spinning holes are regular squares a, b,
It is indispensable to use a spinneret provided with a spinning hole in which a small regular square a is divided into four equal parts c and d. Furthermore, in the method of the present invention, as shown in FIG. 4, it is necessary that the spinneret has a plurality of spinning holes arranged in an annular shape with the missing portions of the small squares a oriented toward the center of the spinneret.

It is desirable that the spinning holes in the spinneret are arranged at intervals of preferably 2.5 mm or more, more preferably 3.0 mm or more.
If it is less than mm, the formation speed of the skin layer at the time of solidification after spinning will be slow, a plurality of irregularities will be formed on the surface, gloss will not be obtained, and fusion of fibers will easily occur.

The fiber immediately after being spun from the spinneret has a cross-sectional shape close to the shape of the spinning hole, but when the solvent evaporates, the surface evaporation rate of the portion corresponding to the missing portion of the spinning hole is It is slower than the surface evaporation rate of other parts, and the formation of the skin layer is delayed. Therefore, during the volume contraction due to the evaporation of the solvent inside the fiber, the stress of the volume contraction concentrates in the part corresponding to the missing part of the spinning hole, and it collapses toward the inside of the fiber. Both ends of the part corresponding to the part other than the missing part approaching inside are close to each other to form a pseudo hollow part having a slit-like opening or closely adhering to close the opening, and the fiber cross section has a substantially triangular shape. Become. The portion corresponding to the portion other than the missing portion of the spinning hole has a fast surface evaporation rate, a skin layer is quickly formed, and there is no concentration of stress at the time of volume contraction, so that a smooth concave curved surface is formed in the fiber cross section. Become.

Further, in a spinneret in which a plurality of spinning holes are simply arranged in an annular shape, the solvent evaporated from the fiber immediately after spinning is present in a high concentration in the central portion of the spinneret, and the atmospheric temperature is lowered to cause evaporation. Although it is difficult to proceed, in the method of the present invention, in the spinneret, a plurality of spinning holes are arranged annularly toward the center of the spinneret so that a delay in the evaporation rate of the solvent is positively performed. By using it, it is possible to more stably obtain a substantially triangular fiber cross section exhibiting excellent gloss and dry feeling. In addition, when a plurality of spinning holes are arranged in an annular shape in which the missing parts of the small square are directed in the direction opposite to the center of the spinneret, the hollow section is not formed and the fiber cross section does not have a triangular shape. No smooth surface can be obtained.

In the method of the present invention, during dry spinning of cellulose acetate, the spinning conditions are not particularly limited except that the above-mentioned specific spinneret is used.
The special cross-section cellulose of the present invention, which does not cause yarn breakage or welding and has improved gloss, by setting a temperature lower than 65 to 75 ° C., which is a spinning dope temperature in ordinary dry spinning, and preferably 50 to 60 ° C. The acetate yarn can be obtained more stably. Moreover, according to the method of the present invention, preferably, the single fiber fineness is 3.3 to 11.1 Dtex.
It is possible to obtain a cellulose acetate yarn having a special cross-section with a stable cross-sectional shape.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. The evaluation items in the examples were measured according to the following methods.

[Hollowness] The proportion (%) of the pseudo hollow portion in the total cross-sectional area was determined from the scanning micrograph of the fiber cross section.

[Glossiness] A sample yarn was tightly wound around a flat plate under tension of 0.1 g / Dtex into 6 layers with a length of 42 mm and a width of 35 mm, and a gloss meter (manufactured by Nippon Denshoku Co., Ltd., 300A) was used.
Was measured under a reflection condition of 45 °.

[Texture] A knitted fabric having a plain knitting structure was knitted using a sample yarn, and after scouring dyeing, a sensory evaluation was performed by touch and visual inspection. At this time, a normal cellulose acetate yarn formed by using a spinneret having a circular spinning hole shape (Comparative Example 1)
Based on the knitted fabric using, the one with a slightly weak gloss is △, the one with a slightly strong gloss is ○, and the one with a strong gloss is ◎
The glossiness and the feel of wet or dry were judged.

Examples 1 to 3 Cellulose acetate having an acetylation degree of 61.6% was dissolved in a methylene chloride / methanol mixed solvent (91/9) to prepare a spinning dope having a polymer concentration of 21.95% by weight. This spinning stock solution was kept at 60 ° C., and the missing holes of 22, 15, and 8 spinning holes each having the shape of the present invention were annularly formed with the missing hole portions facing the center of the spinneret.
Using three types of spinnerets arranged in 69 mm, each spinneret was discharged into heated air at 110 ° C., and spinning speed was 500.
spinning at m / min, bright 111Dtex / 22f,
Cellulose acetate yarns of 61 Dtex / 15f and 83 Dtex / 8f were obtained, respectively. Table 1 shows the evaluation results of the cross-sectional shape, the pseudo hollow ratio, the B / A ratio, and the feel of the knitted fabric of the obtained cellulose acetate yarn.

(Comparative Examples 1 to 3) The same spinning dope as used in Example 1 was used, and this spinning dope was kept at 60 ° C. to form circular spinning holes with a triangular shape Spinning was performed in the same manner as in Example 1 except that the arranged spinneret was used, and Bright 111Dtex / 26f, 111
Dtex / 22f and 111 Dtex / 22f cellulose acetate yarns were obtained, respectively. Table 1 shows the evaluation results of the cross-sectional shape, the pseudo hollow ratio, the glossiness, and the feel of the knitted fabric of the obtained cellulose acetate yarn.

[0024]

[Table 1]

(Examples 4 to 5, Comparative Examples 4 to 5) Example 1
Using the same spinning dope as used in step 1,
And using two kinds of spinnerets in which 26 and 30 spinning holes each having the shape of the present invention are annularly arranged with the missing portions facing the center of the spinneret at the spinning hole intervals shown in Table 2. Spinning was carried out in the same manner as in Example 1, and bright 111 Dte
Cellulose acetate yarns of x / 26f and 167Dtex / 30f were obtained, respectively. The evaluation results of the cross-sectional shape stability of the obtained cellulose acetate yarn are shown in Table 2.

[0026]

[Table 2]

(Example 6, Comparative Examples 6 to 7) The same spinning dope as used in Example 1 was used, and spinning was carried out in the same manner as in Example 1 except that the spinning dope was kept at the temperature shown in Table 3. Bright 111Dtex / 22f cellulose acetate yarns were obtained. Table 3 shows the evaluation results of the cross-sectional shape stability and glossiness of the obtained cellulose acetate yarn.

[0028]

[Table 3]

[0029]

EFFECTS OF THE INVENTION The special cross-section cellulose acetate yarn of the present invention has a drastically improved glossy feeling which is not found in conventional cellulose acetate yarns, and also has a dry feeling, and is suitable as a woven or knit material. is there. Further, according to the method of the present invention, such a special cross-section cellulose acetate yarn of the present invention can be stably obtained.

[Brief description of drawings]

FIG. 1 is a fiber cross-sectional view of a special cross-section cellulose acetate yarn of the present invention.

FIG. 2 is a fiber cross-sectional view of an example of a conventional cellulose acetate yarn.

FIG. 3 is a plan view of spinning holes of a spinneret used in the method of the present invention.

FIG. 4 is a partial layout view of spinning holes in the spinneret used in the method of the present invention.

FIG. 5 is a photograph (400 times magnification) of a fiber cross section of an example of a cellulose acetate yarn having a special cross section of the present invention.

[Explanation of symbols]

a Small square (missing part) b small square c small square d small square

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 60-134012 (JP, A) JP 37-7917 (JP, B1) International publication 96/35010 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) D01F 1/00-9/04 D01D 5/253

Claims (4)

(57) [Claims] 1. A cellulose acetate yarn having a degree of acetylation of 48.5% or more, wherein the fiber cross section has a substantially triangular shape and spreads from approximately the center of one side toward the center of the fiber cross section, and the end on the side side. Has a pseudo hollow portion opened or closed like a slit in the fiber cross section, and the area of the pseudo hollow portion is 2 to 10 of the total cross sectional area.
Special cross-section cellulose acetate yarn characterized by occupying 100%. 2. The special cross-section cellulose acetate yarn according to claim 1, wherein the other two sides of the fiber cross section having a substantially triangular shape form a smooth concave curve. 3. A spinning hole having a shape in which, when dry-spinning cellulose acetate having an acetylation degree of 48.5% or more, a regular square is divided into four regular squares, and one small regular square is omitted. A method for producing a cellulose acetate yarn having a special cross section, which comprises using a spinneret in which a plurality of spinning holes are arranged in an annular shape with the missing portions facing the center of the spinneret. 4. The method for producing a special cross-section cellulose acetate yarn according to claim 3, wherein the spinning holes are arranged at intervals of 2.5 mm or more.