JPH07229016A - Method for producing cellulose fiber - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for producing a cellulose fiber having good spinning stability by improving a spinning nozzle used for forming a fiber using a cellulose solution. Composition: N-methylmorpholine N-oxide, N
At least one cellulose solution consisting of a mixed solvent consisting of a solvent that can be uniformly mixed with methylmorpholine N-oxide and is insoluble in cellulose, and a cellulose composition dissolved in this mixed solvent system. Is discharged into the air from a spinning nozzle having a spinning hole, and the discharged filamentous cellulose solution flow is brought into contact with a coagulating liquid while drafting the coagulating liquid to coagulate the obtained coagulated fiber from the coagulating liquid. In the method for forming cellulose fibers by taking them off, the diameter (D) of the spinning hole of the spinning nozzle.
And the ratio (L / D) of the length of the spinning hole (L) is 10 or more,
A spinning nozzle whose material is ceramics is used.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing cellulose fibers. More specifically, the present invention relates to a method for producing a cellulose fiber having improved spinning stability by improving a spinning nozzle used when forming a fiber using a cellulose solution.

[0002]

2. Description of the Related Art Viscose method and copper-ammonia method have been conventionally known as methods for producing cellulose fibers, but there is a problem of environmental pollution because it is difficult to reuse the solvent.
In consideration of the safety to the environment, a method for producing a molded article such as a fiber or a film by adjusting a cellulose solution in which N-methylmorpholine N-oxide aqueous solution is dissolved is disclosed in Japanese Examined Patent Publication No. Sho 60-28848 (or Corresponding US Pat. No. 4,246,221 and US Pat. No. 4
No. 416698), this method is advantageous in that the solvent can be recovered from the spinning bath and reused.

Further, Japanese Patent Laid-Open No. 4-308220 (or corresponding US Pat. No. 5,252,284) discloses a method of spinning a fine denier yarn with a low spinning draft from a spinning nozzle having a small pore size using the above solution. Is disclosed.

Generally, a solution of cellulose in N-methylmorpholine N-oxide has a high viscosity and also has a large elastic behavior as a viscoelastic body. Since such a solution having a high viscosity is difficult to deform, it is difficult to increase the spinning draft ratio (take-off speed / the linear velocity of the solution discharged from the spinning hole).

Further, when molding is performed using a nozzle having a small hole diameter or a slit having a narrow width, when the discharge amount is increased, melt fracture (a large turbulence of the solution flow at the outlet of the spinning hole) occurs. Therefore, the range in which stable molding can be performed is limited to a low discharge region where melt fracture does not occur, which is a factor of lowering productivity.

On the other hand, the spinning nozzle has been improved in order to improve the stability of spinning, for example, Japanese Patent Publication No. 43-2.
Japanese Patent No. 0254 discloses a polynosic filament capable of significantly reducing the apparent viscosity of viscose at the time of discharge by using a glass nozzle having a specific hole diameter and hole length, and reducing the yarn breakage at the time of spinning and the nozzle clogging. A method of spinning at high speed is disclosed. Further, there is a method for improving spinning stability by using a ceramic nozzle having a specific shape when spinning an inorganic continuous fiber.
No. 07 publication.

[0007]

As described above, in the method according to the prior art, N-methylmorpholine N-oxide and N-methylmorpholine N-oxide can be uniformly mixed, and cellulose can be mixed. Even if an attempt is made to spin a cellulose solution composed of an insoluble solvent and a mixed solvent consisting of the above and a cellulose composition dissolved in the mixed solvent system at a high speed, this cellulose solution is extremely different from a stock solution for spinning other polymers. Since it exhibits elastic behavior as a strong viscoelastic body, melt fracture easily occurs and it is difficult to stably obtain finely divided cellulose fibers. The present invention aims to solve these problems.

[0008]

Means for Solving the Problems The gist of the present invention is to provide a solvent (that is capable of uniformly mixing N-methylmorpholine N-oxide and N-methylmorpholine N-oxide, and incapable of dissolving cellulose). (Hereinafter referred to as non-solvent of cellulose), and a cellulose solution comprising a cellulose composition dissolved in the mixed solvent system are discharged into the air from a spinning nozzle having at least one spinning hole, The filamentous cellulose solution flow thus prepared is brought into contact with a coagulating liquid while being drafted to coagulate the obtained coagulated fiber, and the obtained coagulated liquid is taken from the coagulating liquid to form a cellulose fiber. Ratio (L / L) of diameter (D) of spinning hole and length (L) of spinning hole
D) is 10 or more, and a spinning nozzle made of a ceramic material is used.

In the present invention, as the spinning nozzle, a spinning nozzle having a spinning hole having a ratio L / D of the diameter D of the spinning hole and the length L of the spinning hole of 10 or more, more preferably 15 or more is used. By spinning, it is possible to perform spinning with higher draft and stability. Furthermore, the diameter D of the spinning hole is 200
It is preferably at least μm. Since the cellulose solution used in the present invention has high elastic behavior, the diameter D of the spinning hole is 200.
less than μm, or the ratio L / D of the diameter D and the length L is 1
If it is less than 0, melt fracture tends to occur. Since this phenomenon is remarkable especially at the time of high discharge, the maximum spinning draft ratio cannot be set large, and it becomes difficult to obtain stable and uniform fiber at high speed.

The spinning nozzle used in the present invention must be made of a ceramic material, and even if the L / D is 10 or more, it is a metal nozzle that is usually used and the cellulose solution used in the present invention is used. Spinning, the melt fracture becomes severe on the high discharge side, and the MDR (maximum winding speed / discharge linear velocity ratio) decreases, making it difficult to wind fine denier yarn at high speed. Become.

The ceramic portion of the spinning nozzle used in the present invention may have at least the inner surface of the spinning hole through which the spinning dope passes through ceramics. Therefore, the spinning hole surface of the metal nozzle may be coated with ceramics, or may be made of metal. It is also possible to embed a ceramic chip having a spinning hole in the spinning nozzle. Needless to say, the entire spinning nozzle may be made of ceramics.

The term "ceramic" as used in the present invention means aluminum oxide, magnesium oxide, beryllium oxide, zirconium oxide and mixtures thereof, and zirconium oxide is particularly preferable in the present invention.

The cellulose component used in the present invention (hereinafter referred to as component [1]) is a cellulose having a polymerization degree of 500 to 2000, preferably 500 to 1000, and a polymerization degree of 5
When it is less than 00, the mechanical properties such as strength and elongation of the molded product are deteriorated, and when it exceeds 2000, the moldability of the cellulose solution is deteriorated.

Further, in addition to the above-mentioned cellulose, a cellulose derivative, a polysaccharide, and a cellulose having a degree of polymerization of 400 to 900 and a degree of polymerization of 90% or less with respect to the degree of polymerization of the cellulose and having different degrees of polymerization. (Hereinafter, referred to as component [2]) may be added to the cellulose solution.

Any cellulose derivative may be used as long as it is soluble in a mixed solvent system consisting of N-methylmorpholine N-oxide and a non-solvent of cellulose, specifically, cellulose diacetate, cellulose triacetate,
Hydroxypropyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and the like,
Of these, cellulose diacetate is particularly effective in improving spinnability.

As the polysaccharide, any one can be used as long as it can be dissolved in a mixed solvent system consisting of N-methylmorpholine N-oxide and a non-solvent of cellulose, and specifically β-
Examples thereof include 1,3 glucose and α-1.4 glucose. Among them, β-1,3 glucose is particularly effective for improving spinnability.

The blending weight ratio [1]: [2] of the component [1] and the component [2] is 95: 5 to 50:50. When the ratio of the component [2] is less than 5, the spinnability is improved. If the effect is not sufficient, on the contrary, if it exceeds 50, the mechanical properties such as strength and elongation of the obtained molded article deteriorate.

As the cellulose used in the component [1] or the component [2] of the present invention, dissolved pulp, pulp floc and the like can be used, but these pulps may contain hemicellulose, lignin and the like. Among these, pulp containing 90% by weight or more of α-cellulose is preferable.

The pulp may be in the form of a sheet or a powder, and the sheet may be made into a chip by a cutting machine such as a shredder. Further, it may be pulverized into particles as long as the molecular weight of cellulose is not significantly reduced.

The solution used in the present invention is cellulose, N-
It is composed of a mixed solvent consisting of methylmorpholine N-oxide and a non-solvent of cellulose. Here, N-methylmorpholine N-oxide is used as a solvent for cellulose, but depending on the case, Japanese Patent Publication No. 55-41691.
No. 5, Japanese Patent Publication No. 55-46162 and Japanese Patent Publication No. 55-416
93 (or corresponding US Pat. No. 4,211,574)
No. 4,142,913 and No. 4,144,080), it is possible to use in combination with other tertiary amine oxides. In this case, as the other tertiary amine oxide that can be used in combination, particularly preferable is a cyclic mono (N-methylamine-N-oxide) compound similar to N-methylmorpholine N-oxide. Examples thereof include N-methylpiperidine-N-oxide and N-methylpyrrolidone oxide.

The preferred non-solvent for cellulose used in the present invention is water, but it may be a mixture of water and an alcohol such as methanol, n-propanol, isopropanol or butanol, and N-methylmorpholine. Any aprotic organic solvent such as toluene, xylene, dimethylsulfoxide, dimethylformamide, dimethylacetamide, etc. can be used as a nonsolvent for cellulose as long as it does not chemically react with N-oxide or cellulose.

In addition, stabilizers can be added to the mixed solvent system. Most preferred as such a stabilizer is propyl gallate, which is disclosed in JP-B-3-2981.
No. 9 (or corresponding US Pat. No. 4,426,228)
Other gallic acid esters, such as methyl gallate, ethyl gallate, isopropyl gallate, and the like, carbonyl double glycerin aldehyde, L-ascorbic acid, isoascorbic acid, triose lectductone, reductic acid, etc. Compounds with adjacent bonds can be used as stabilizers. Further, ethylenediaminetetraacetic acid or the like can also be used as a stabilizer. Further, as an inorganic compound effective as a stabilizer, calcium pyrophosphate or calcium chloride described in US Pat. No. 4,880,469,
Ammonium chloride or the like can also be used.

The cellulose solution can be prepared either continuously or batchwise. That is, dissolution adjustment may be continuously performed using a screw type extruder or the like, or batch dissolution adjustment may be performed using a tank type kneader equipped with a device that can be heated and degassed under reduced pressure. Although the melting temperature is not particularly limited, it is preferably carried out in the range of about 90 to 120 ° C. If the temperature is too high, the degree of polymerization is lowered due to the decomposition of cellulose, the decomposition of the solvent and the coloring become remarkable.

The concentration of cellulose in the cellulose solution is 3
It is 0% by weight or less, preferably in the range of 6 to 25% by weight from the viewpoint of moldability and productivity of the cellulose molded product. Further, N-methylmorpholine N-oxide in a cellulose solution and N-methylmorpholine N- which is a non-solvent of cellulose
The ratio of the solvent that can be mixed with the oxide is 48 to
90% by weight and 5 to 22% by weight are preferable. When water is used as the non-solvent for cellulose, the proportion of water is set to a large value of 20 to 50% by weight at the stage of adding cellulose to the mixed solvent with N-methylmorpholine N-oxide, and the pressure is reduced. Water is removed under heating, and the water content is adjusted to
It is preferably 22% by weight.

Next, a method of spinning cellulose fibers using the cellulose molding solution of the present invention will be described. First, a mixed solvent solution of a cellulose composition prepared by a dissolver is delivered to a spinning nozzle by a gear pump. Transport in quantity. The solution is once cooled and solidified, and the solidified product is crushed into an appropriate shape, and then fed into a melt extruder, where it is heated and redissolved, and a fixed amount is passed through a gear pump to a spinning nozzle. You may convey by.

The spinning method itself is a conventionally known spinning method, that is, a cellulose solution is discharged into the air from a spinning nozzle,
It is possible to employ a method in which the formed filamentous solution flow is drafted and brought into contact with a coagulation liquid to coagulate it, and the solidified cellulose fibers are taken out from the coagulation liquid.

The coagulating liquid used in the present invention is one or a mixture of two or more selected from non-solvents of cellulose such as water, alcohols such as methanol and ethanol,
Alternatively, a mixed solvent of the non-solvent of cellulose and N-methylmorpholine N-oxide is preferable, and more preferably water or a mixed solvent of water and N-methylmorpholine N-oxide is used. Furthermore, a tertiary amine oxide of Tan, which can be uniformly mixed with N-methylmorpholine N-oxide, may be added to these mixed solvents.
Alternatively, dimethyl sulfoxide or dimethylformamide may be added to the mixed solvent. Further, a pH adjusting agent such as acetic acid may be added to these coagulation liquids.

[0028]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, the degree of cellulose polymerization was determined by formula [η] = 1.40 when the viscosity was measured at 34 ° C. using a 1: 1 mixed solvent of N-methylmorpholine N-oxide.H ₂ O and dimethyl sulfoxide. It is the viscosity average degree of polymerization determined from 99 × 10 ^-2 DP ^0.79 .

The maximum take-up speed and MDR (maximum take-up speed / discharge linear velocity ratio) are values when half of the taken-up yarns are broken.

(Example 1) 3000 g of N-methylmorpholine-N-oxide containing 360 g of cellulose (viscosity average degree of polymerization DP = 1000) and 40% by weight of water.
Are mixed, and the pressure is reduced to about 9 while heating to about 100 ° C with stirring.
A spinning stock solution (cellulose concentration: 15% by weight) was prepared by distilling 60 g of water. The solution was spun at a temperature of 135 ° C.
The fiber was extruded from a ceramics (zirconium oxide) spinning nozzle having 36 spinning holes with a diameter of 300 μm and an L / D of 20, and then passed through a space gap of about 50 cm, then coagulated with water and the yarn was taken out. A yarn of 1.7d was stably taken out under the conditions of a discharge amount of 0.583 g per spinning hole and a take-up speed of 500 m / min. At this time, the maximum take-up speed was 650 m / min.

Comparative Example 1 A spinning stock solution prepared in the same manner as in Example 1 was used except that the spinning nozzle was made of metal (stainless steel) having a diameter of 300 μm and 15 spinning holes having an L / D of 15. In the same manner as in Example 1, the fiber was spun and collected. When the discharge amount per spinning hole was 0.583 g, the maximum winding speed was 540 m / min, and stable take-up could not be performed at 500 m / min or more.

Comparative Example 2 The spinning dope prepared in the same manner as in Example 1 was discharged from the spinning nozzle and taken out in the same manner as in Example 1 except that the spinning hole L / D was set to 5. When the discharge amount per spinning hole was 0.583 g, the maximum winding speed was 210 m / min, and it could not be taken over at 500 m / min or more.

[0033]

According to the present invention, a mixed solvent consisting of N-methylmorpholine N-oxide and a solvent capable of uniformly mixing N-methylmorpholine N-oxide and insoluble in cellulose, Also, a cellulose solution composed of a cellulose composition dissolved in this mixed solvent system can be stably spun at high speed. Furthermore, since the yarn can be taken up with a high spinning draft, fine denier fibers can be obtained with high productivity.

Front page continuation (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location D01D 4/02 5/06 Z (72) Inventor Shoji Hayashi 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Central Research Institute Co., Ltd. (72) Inventor Hideaki Habara 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratories

Claims (3)

[Claims] 1. A mixed solvent comprising N-methylmorpholine N-oxide and a solvent capable of uniformly mixing N-methylmorpholine N-oxide and insoluble in cellulose, and a mixed solvent thereof. At least one cellulose solution consisting of the cellulose composition dissolved in the system
It is discharged into the air from a spinning nozzle having individual spinning holes, and the discharged filamentous cellulose solution flow is brought into contact with a coagulating liquid while drafting it to coagulate the obtained coagulated fiber, In the method of forming a cellulose fiber by taking it out of the spinning nozzle, the ratio (L / D) of the diameter (D) of the spinning hole and the length (L) of the spinning hole of the spinning nozzle is 10 or more, and the material is A method for producing a cellulose fiber, which comprises using a spinning nozzle made of ceramics. 2. The method for producing a cellulose fiber according to claim 1, wherein the ceramic is zirconium oxide. 3. The take-up speed is 500 m / min or more, and the single fiber fineness of the taken-out cellulose fibers is 3
The method for producing a cellulose fiber according to claim 1 or 2, which has a denier or less.