JPH07331527A - Production of cellulose acetate fiber - Google Patents

Abstract

PURPOSE:To stably dry spin a spinning solution of cellulose acetate at a high speed. CONSTITUTION:This method for producing cellulose acetate fibers is to use a spinneret, having >=1 ratio (L/D) of the length (L) of a discharge part 4 of each spinning hole 2 to the diameter (D) thereof in the spinneret and comprising a material of the inner periphery thereof of a ceramic, preferably zirconium oxide in discharging a spinning solution containing cellulose acetate dissolved therein from the spinneret 1 and dry spinning the spinning solution. Thereby, the spinning stability is increased within a winding speed range at a lower speed than that of a conventional dry spinning method using a spinneret made of stainless steel without causing trouble such as yarn breakage and the cellulose acetate fibers can be produced at a high winding speed impracticable according to the conventional method using the spinneret made of the stainless steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cellulose acetate fiber by dry spinning a cellulose acetate spinning dope stably and at a high speed.

[0002]

2. Description of the Related Art Cellulose acetate fibers have characteristics such as excellent color developability and dry texture, and are utilized in the fields of linings for clothes and beddings by taking advantage of these characteristics.
Industrially, cellulose acetate fibers are produced by a dry spinning method, while cellulose diacetate fibers are generally produced by a dry spinning method from a spinning dope using a solvent of acetone or acetone and water as a solvent, The cellulose triacetate fiber is produced by a dry spinning method from a spinning dope containing methylene chloride or a mixture of methylene chloride and methanol as a solvent.

In these dry spinning methods of cellulose acetate fibers, the spinneret has a great influence on the spinnability. As an example of studying the influence of the spinneret on the spinnability, Japanese Patent Publication No. 43-20254 discloses that a glass-based spinneret having a specific pore length and pore diameter is used when spinning a cellulosic (viscose) fiber. As a result, it is disclosed that viscose having a high viscosity can be spun at a high speed as compared with a metal spinneret.

Further, when spinning inorganic fibers, Japanese Patent Laid-Open No.
No. 41012 discloses that a ceramic spinneret produced by a specific method has good spinnability.
No. 25007, a method for obtaining a spinneret excellent in wear resistance and corrosion resistance by embedding and fixing a ceramic chip having a specific shape and structure so as to form a protrusion on the stock solution discharge side of a spinneret plate. Is disclosed.

Further, in Japanese Patent Laid-Open No. 58-76512,
A spinneret with high dimensional accuracy and good quality, in which a chip made of a ceramic having a stock solution introduction hole and a stock solution discharge hole connected to the stock solution is pushed into a spinneret plate, is disclosed in JP-A-63-3156.
In No. 05, at least the discharge surface of the spinneret and the inner surface of the polymer discharge hole are coated with two or more layers of ceramic coatings made of different materials, so that the finished state is smooth and the wetting of the polymer is suppressed. Disclosed is a spinneret capable of suppressing the spread of a polymer and cleaning the spinneret surface without damaging the discharge holes.

[0006]

Generally, the spinning speed of the cellulose acetate fiber in the dry spinning method is 300-300.
It is 800 m / min, and spinning at a higher speed is industrially advantageous, but technically difficult. The reason for this is that if a spinning speed of more than 800 m / min is attempted, the filaments obtained will have uneven yarn and poor mechanical properties, or in extreme cases, spinning process troubles such as yarn breakage will occur immediately after discharge. Because you will be able to do it.
It is thought that uneven discharge can be reduced by lowering the concentration of acetate in the spinning dope to reduce the viscosity of the dope.
The solvent drying process after spinning is complicated and technically extremely difficult.

In view of such a situation, an object of the present invention is to
It is an object of the present invention to provide a method for producing a cellulose acetate fiber which is industrially stable at a high spinning speed and does not deteriorate the physical properties of the yarn.

[0008]

Means for Solving the Problems That is, according to the present invention, when a spinning stock solution in which cellulose acetate is dissolved is discharged from a spinneret for dry spinning, the diameter (D) of a discharge portion of a spinning hole of the spinneret. To length (L) ratio (L / D)
A method for producing a cellulose acetate fiber is characterized by using a spinneret having a number of 1 or more and an inner peripheral material of which is ceramic.

In the ceramic portion of the spinneret used in the present invention, at least the inner surface of the spinning hole through which the spinning dope passes is ceramic. Therefore, the spinneret surface of the metal spinneret is coated with ceramic, or It may be one in which a ceramic chip having a spinning hole is embedded in the spinneret. It goes without saying that the entire spinneret may be made of ceramic.

The type of ceramic is not particularly limited, and alumina oxide, zirconium oxide, silicon oxide, tungsten carbide, chromium carbide, silicon carbide, silicon nitride, etc. can be used, but the spinneret of the present invention is preferable. Zirconium oxide.

The diameter (D) of the discharge portion of the spinning hole is usually 0.03 mm to 0.1 mm, but the length of the discharge portion is required to achieve spinning at a high speed exceeding 1000 m / min. The ratio (L / D) of (L) to the diameter (D) needs to be 1 or more, preferably 7 or more, more preferably 10 or more.

The present invention will be described in detail below with reference to the drawings. 1, 2 and 3 are sectional views showing an example of the spinneret used in the present invention. In the spinneret shown in FIG. 1, the spinneret plate 1 is entirely made of ceramic, and the spinning hole 2 is composed of an introduction part 3 and a discharge part 4. The spinneret shown in FIG. 2 has a structure in which a spinning hole 2 portion made of ceramic is fitted and fixed to a metallic spinneret plate 1. The spinneret shown in FIG. 3 has a structure in which the inner surface of the spin hole of a metal spinneret is coated with ceramic. Figure 2
In the case of FIG. 3, the spinneret body is made of stainless steel, platinum,
Any of platinum alloys and the like may be used.

The cellulose acetate fiber of the present invention may be spun according to a usual dry spinning method. That is, a solution in which acetate is dissolved by a usual method is filtered to prepare a spinning dope, heated to 30 to 150 ° C., discharged from a spinneret, dried by a usual method, and wound to obtain a cellulose acetate fiber. Obtainable.

As the cellulose acetate used in the present invention, cellulose diacetate having an average acetylation degree of 48.8% to 56.2% and average acetylation degree of 56.2% to 62.5%.
Cellulose triacetate can be mentioned.

Further, examples of the solvent for spinning dope used in the present invention include acetone (boiling point = 56.5 ° C.) and methylene chloride (39.75 ° C.). In addition, in order to improve the spinnability, a system in which a cosolvent such as water or alcohol is added to these solvents may be used.

[0016]

The present invention will be described in more detail with reference to the following examples. (Example 1) A solution having a concentration of 28.8% by weight in which a cellulose diacetate having an average acetylation degree of 55% was dissolved in a mixture of acetone / water (95/5) was filtered to prepare a spinning dope.
While keeping the temperature of this spinning solution at 83.5 ° C., a spinneret having a zirconium oxide spinning hole fitted and fixed to a stainless steel spinneret body as shown in FIG. 2 (pore diameter 0.04 m
m, number of holes 20, L / D = 1, 3, 7), and dry spinning was carried out at a discharge linear velocity of 1600 m / min and a spinning draft of 0.8. The results are shown in Table 1. For comparison, a stainless steel spinneret (hole diameter 0.04 mm, number of holes 20, L
The results using / D = 1) are also shown in Table 1. In addition, the discharge linear velocity is (the discharge amount of the spinning dope) / (total hole area of the spinneret)
The spinning draft is a value defined by (discharge linear velocity) / (take-up velocity). Table 1 also shows the results of measuring the maximum winding speed (m / min) while increasing the spinning speed.

[0017]

[Table 1]

(Example 2) Using the same spinning dope as in Example 1, zirconium oxide spinning holes were fitted and fixed to the stainless spinneret body with L / D of 10 as shown in FIG. Using the above spinneret (pore diameter 0.04 mm, hole number 20), dry draft was performed at a spinning draft of 0.8 and a discharge linear velocity as shown in Table 2. The results are shown in Table 2. For comparison, a stainless steel spinneret (hole diameter 0.04 mm,
Table 2 also shows the results using 20 holes and L / D = 1). With such a discharge linear velocity, even with a stainless steel spinneret,
Spinning was possible, but the maximum winding speed at that time was higher when the ceramic spinneret was used, and spinning stability was higher.

[0019]

[Table 2]

[0020]

EFFECTS OF THE INVENTION According to the present invention, the spinning stability is increased and there is no trouble such as yarn breakage in the lower spinning speed range than in the conventional dry spinning method using a stainless steel spinneret, and moreover, It has become possible to produce cellulose acetate fibers at a high winding speed, which was not possible with the conventional method using a stainless steel spinneret.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of an example of a spinneret of the present invention.

FIG. 2 shows a cross-sectional view of another example of the spinneret of the present invention.

FIG. 3 shows a cross-sectional view of another example of the spinneret of the present invention.

[Explanation of symbols]

 1: Spinneret plate 2: Spinning hole 3: Introduction part 4: Discharge part L: Discharge part length D: Discharge part diameter

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eiichi Hamada 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Shoji Hayashi 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Inside Rayon Co., Ltd. Central Research Laboratory (72) Inventor Shigeki Hakura 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A dry spinning solution in which cellulose acetate is dissolved is discharged from a spinneret for dry spinning.
Diameter (D) and length (L) of the discharge portion of the spinning hole of the spinneret
A method for producing a cellulose acetate fiber, characterized in that a spinneret having a ratio (L / D) of 1 or more and an inner peripheral material of which is ceramic is used. 2. The method for producing a cellulose fiber according to claim 1, wherein the ceramic is zirconium oxide.