JP2003055832A - Method for producing solvent-spun cellulose fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a solvent-spun cellulose fiber by which the fiber can be stably and industrially produced by reducing the viscosity of a cellulose spinning dope using a tertiary amine oxide as a solvent. SOLUTION: This method for producing the solvent-spun cellulose fiber comprises spinning the spinning dope containing a Li compound in the tertiary amine oxide solution of the cellulose. Preferably, the concentration of the cellulose included in the spinning dope is >=10 wt.%, and the polymerization degrees of the cellulose and the obtained cellulose fiber are >=600 and >=350, respectively.

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 solvent-spun cellulose fibers, and more specifically to a technique for forming a cellulose raw material into a tertiary amine oxide solution to form fibers.

[0002]

2. Description of the Related Art Cellulose is replaced by N instead of the viscose method.
-Methylmorpholine-N-oxide (hereinafter NMMO)
A method of forming a hydrate using a solvent is industrially used, and a representative example thereof is cellulose fiber lyocell (Lyocell).
cell) is well known. NMMO is a kind of tertiary amine oxide and is an organic solvent. N for cellulose
A method for producing cellulose fibers using MMO hydrate as a solvent is disclosed in JP-B-60-28848, and has recently been attracting more attention because of its light environmental load and excellent physical properties.

The viscosity of the spinning dope obtained by dissolving cellulose in NMMO is relatively high, and it is difficult to stably eject the spinning dope from the spinneret. for that reason,
The concentration of cellulose in the spinning dope must be lowered or the temperature during spinning must be raised to reduce the viscosity of the spinning dope.
However, lowering the cellulose concentration is not preferable because it lowers the production capacity and increases the cost for recovering the solvent. On the other hand, when the spinning temperature is increased, the degree of polymerization of cellulose is decomposed by heat and greatly attenuated, and the strength of the product is lowered, which is not preferable. These are technical problems to be overcome in this manufacturing method.

In order to overcome these problems, N-methylolcaprolactam as a second solvent was added to NMMO at 30%.
Japanese Patent Application Laid-Open No. 11-323655 discloses a technique for reducing the melt viscosity of a spinning dope by mixing about 10% by weight. However, in this method N2 as the second solvent
-It is not an industrial production method because the amount of methylolcaprolactam used is too large and it is difficult to industrially obtain N-methylolcaprolactam.

As one of the solution systems capable of directly dissolving cellulose, dimethylacetamide (DMAc) and L
A mixed solution system of iCl is known. However, this solution system has a problem that cellulose cannot be dissolved unless a large amount of LiCl is added.

[0006]

Therefore, the present invention is based on N
An object of the present invention is to provide a method for producing a solvent-spun cellulose fiber which is stable and can be industrially produced by reducing the viscosity of a cellulose spinning stock solution using a tertiary amine oxide such as MMO as a solvent.

[0007]

According to the present invention, the viscosity of a stock solution for spinning cellulose using a tertiary amine oxide such as NMMO as a solvent can be reduced by the means described below.

That is, the first invention is a method for producing a solvent-spun cellulose fiber, which comprises spinning a spinning dope containing a compound having a Li (lithium) atom in a solution of cellulose tertiary amine oxide. Is. A second invention is the method for producing solvent-spun cellulose fibers according to the first invention, wherein the concentration of cellulose contained in the spinning dope is 10% by mass or more.

Furthermore, the first or second invention is characterized in that the third invention raw material cellulose has a degree of polymerization of 600 or more, and the cellulose fiber produced by spinning the spinning dope has a degree of polymerization of 350 or more. The method for producing a solvent-spun cellulose fiber according to the invention.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The present invention reduces the viscosity of the spinning dope by incorporating the Li compound into the spinning dope to use the viscosity of the cellulose spinning dope using NMMO as a solvent. Examples of the Li compound in the present invention include LiCl, CH ₃ CO
Examples thereof include OLi and C ₂ H ₅ COOLi, but the present invention is not limited to these compounds. That is,
The effects of the present invention are exhibited even in various compounds such as Li salt of carboxylic acid and Li salt of sulfonic acid.

When preparing the spinning dope, the amount of the Li compound added is 0.1 to 2.0 with respect to the mass of cellulose.
It is% by mass. When the amount of the Li compound added is within this range, the solubility of cellulose is not affected and uniform dissolution is possible. If it is less than 0.1% by mass, the effect is small and the viscosity is not sufficiently reduced, and the productivity is not improved. Further, the viscosity of the spinning dope decreases as the addition amount increases, but even if the amount is more than 2.0% by mass, the viscosity reducing effect of the spinning dope does not increase so much and the manufacturing cost increases, which is not preferable. .

It is not clear that the mechanism of decreasing the viscosity of the spinning dope by adding the Li compound is clear, but cellulose has a large number of OH groups,
By adding the Li compound when preparing the spinning solution,
It is presumed that the replacement of H atom and Li atom of the OH group of cellulose occurs, which causes a decrease in the number of hydrogen bonds.

In the present invention, the degree of polymerization of cellulose constituting the fiber is not particularly limited, but the average degree of polymerization of cellulose is preferably about 600 to 1700. Even when cellulose having a high degree of polymerization and cellulose having a low degree of polymerization are mixed, it is possible to prepare a spinning solution having a reduced viscosity. When dissolving cellulose in NMMO hydrate, any of the above Li compounds of the present invention is added at the same time.

By adding any one of the above Li compounds of the present invention, it is possible to uniformly dissolve cellulose without disturbing the dissolution. Further, when dissolving cellulose, it is desirable to further add 0.1 to 2.0% by mass of an antioxidant for the purpose of preventing the decrease of the degree of polymerization of cellulose and the decomposition of NMMO. The temperature at which the cellulose is dissolved is preferably 90 to 135 ° C. Further, the cellulose concentration is preferably adjusted to 5 to 35% by mass because it is easily dissolved uniformly, and is preferably set to 15 to 25% by mass.

The adjusted spinning dope is sent to a spinning head, measured by a gear pump and supplied to a spin pack.
The temperature is preferably 90 to 135 ° C. If the temperature is lower than 90 ° C, the viscosity of the spinning dope is high and it is practically difficult to discharge the solution.
When it exceeds, the degree of cellulose polymerization is remarkably lowered even in the spinning dope containing the antioxidant, which is not preferable. It is effective to perform filtration to remove foreign matters in the spinning dope, and it is preferable to use sand in the spin pack or filter with a mesh metal filter or the like.

The raw spinning solution discharged from the spinneret is stretched in a gap (air gap) between the spinneret and the surface of the coagulating liquid. The air gap may be set to about 10 to 500 mm, and it is preferable to employ a method of actively cooling the discharged yarn using a quench chamber or the like at a high spinning speed. An aqueous solution having an NMMO concentration of about 10 to 30% by mass is preferably used as the coagulation bath, and the coagulation bath temperature is preferably about room temperature. The yarn that has passed through the coagulation bath is subsequently washed with water and dried, and then wound up as a yarn with a winder.

The obtained cellulose fibers are in the form of long fibers or short fibers and can be used for cotton or fiber cloth.
Fiber cloth means solvent-spun cellulose fibers used alone or other materials such as polyester, nylon and acrylic.
It is a woven fabric, a knitted fabric, a non-woven fabric, or the like, which is a mixture of more than one kind.
Specific examples of the mixing method include mixing cotton, mixed spinning, mixed twisting, mixed weaving, and mixed knitting, and the mixing ratio of fibers is not limited.

[0018]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these. The composition of the spinning dope and the average degree of polymerization of cellulose in the examples were confirmed by the methods shown below.

<Evaluation Method for Cellulose Degree of Polymerization> The degree of polymerization of cellulose was measured by the Cucumber ethylenediamine method. A sample is weighed 0.0075 to 0.0085 g and put into a cucumber-ethylenediamine solution. After stirring at room temperature for about 30 minutes to completely dissolve the sample, the measurement was carried out while maintaining a constant temperature of 25 ° C.

<Evaluation Method of Dope Composition> The water content in the spinning dope was measured by a trace water content measuring device (manufactured by Hiranuma Sangyo Co., Ltd., model AQ-7). About 5 g of the test piece was weighed, about 20 ml of absolute ethanol (99.5 mass%) was added, and the mixture was allowed to stand at room temperature overnight and then measured. For the concentration of cellulose in the spinning dope, after measuring the mass of the spinning dope, the spinning dope was thoroughly washed with water to precipitate cellulose. Then, the mass after drying overnight at 60 ° C. was measured. The concentration of cellulose was calculated by the difference between the mass of the spinning dope and the mass after thorough washing with water to precipitate cellulose and drying at 60 ° C. for 24 hours.

The method for preparing the spinning dope and the spinning method are as follows. <Preparation method of spinning dope> In order to produce solvent cellulose fibers, refined wood pulp of each degree of polymerization was used as a raw material. When the cellulose was dissolved in NMMO hydrate manufactured by Nippon Emulsion Co., Ltd., the raw materials were added so that each cellulose concentration was adjusted by mixing under reduced pressure. Further, a Li compound was added to reduce the viscosity of the spinning dope. Moreover, 0.25 mass% of n-propyl gallate was added as an antioxidant to the mass of cellulose. Temperature 110 ℃,
A spinning stock solution was obtained by stirring under reduced pressure for about 3 hours. The adjusted spinning stock solution was sent to a spinning head, weighed by a gear pump and supplied to a spin pack, and discharged using the spinneret of the present invention. The temperature during discharge was kept constant at 110 ° C. In addition, in order to remove foreign matter in the spinning dope, filtration was performed immediately before the spinneret using a mesh metal filter.

<Spinning method> The hole diameter is 0.2 mm and the number of holes is 4
The spinning dope discharged from 0 spinnerets was stretched in an air gap of 40 mm. Moreover, the temperature of the discharged yarn is 23 ° C. and the wind speed is 0.85 m /
It cooled in sec. The coagulation bath is NMM at a temperature of 13 ℃
An aqueous solution having an O concentration of 18 mass% was used. Then 18
After thoroughly washing with water at ℃, it was dried at 82 ℃.

<Example 1> A spinning stock solution was prepared by the above method using purified pulp manufactured by Nippon Paper Industries Co., Ltd. having a degree of polymerization of 800. At this time, 0.2% by mass of LiCl as a viscosity reducing additive was added to the mass of cellulose to prepare a spinning dope. After adjusting the spinning dope, the cellulose concentration was confirmed to be 21.3% by mass. When the obtained spinning dope was discharged at 12.5 g / min by the above method and spinning was carried out at a spinning speed of 300 m / min, no yarn breakage occurred and the spinning state was stable. Table 1 shows the evaluation results, spinnability, fiber physical properties and the like.

<Example 2> Bu having a degree of polymerization of 1180
A spinning stock solution was prepared by the above method using refined pulp manufactured by ckeye. At that time, LiC is used as a viscosity reducing additive.
0.2 mass% of 1 was added to the mass of cellulose to prepare a spinning dope. After adjusting the spinning dope, the cellulose concentration was confirmed to be 20.1% by mass. When the obtained spinning dope was discharged at 10.6 g / min by the above method and spinning was performed at a spinning speed of 240 m / min, yarn breakage occurred once / day, but the spinning state was stable.
Table 1 shows the evaluation results, spinnability, fiber physical properties and the like.

Comparative Example 1 Bu having a degree of polymerization of 1180
The spinning stock solution was prepared by the above method using refined pulp manufactured by ckeye. At that time, the viscosity reducing additive was not added. After adjusting the spinning dope, the cellulose concentration was confirmed to be 20.6% by mass. The obtained spinning dope was discharged at 10.5 g / min by the above method, and the spinning speed was 100 m.
Spinning was carried out at a speed of 1 / min. The discharged spinning dope did not allow stable discharge due to hole bending at the discharge part of the spinneret. It was determined that melt fracture occurred because the viscosity of the spinning dope was high. Further, at a spinning speed of 100 m / min, it was very difficult to obtain a yarn with a winding machine, and spinning was impossible. Table 1 shows the evaluation results, spinnability, fiber physical properties and the like.

<Example 4> Bu having a degree of polymerization of 1620
The spinning stock solution was prepared by the above method using refined pulp manufactured by ckeye. At that time, as the viscosity reducing additive, Li
Cl was added in an amount of 0.2% by mass based on the mass of cellulose to prepare a spinning dope. After adjusting the spinning dope, the cellulose concentration was confirmed to be 15.0% by mass. When the obtained spinning dope was discharged at 19.3 g / min by the above method and spinning was performed at a spinning speed of 325 m / min, yarn breakage occurred twice / day, but the spinning state was stable.

[0027]

[Table 1]

As shown in Table 1, by adding a viscosity reducing agent to the spinning dope, it is possible to achieve a high discharge even in a spinning dope having a high cellulose concentration, and also excellent spinning stability even at a high spinning speed. It can be seen that the property is improved. Also,
It can be seen that high discharge is possible even in a spinning stock solution of a high polymerization degree raw material, and that spinning stability is excellent even at a high spinning speed, and productivity is improved. It is also found that the fiber is improved by using the raw material having a high degree of polymerization.

Example 5 A spinning stock solution was prepared by the above method using a purified pulp manufactured by Nippon Paper Industries Co., Ltd. having a degree of polymerization of 800. At this time, 0.2% by mass of LiCl as a viscosity reducing additive was added to cellulose to prepare a spinning dope. As a result of confirming the cellulose concentration after adjusting the spinning solution, it was 15.4 mass%. The spinning dope thus obtained was discharged at 23.0 g / min by the above method, and the fiber obtained by spinning at a spinning speed of 400 m / min had a polymerization degree of 523.
And the strength is 3.8 cN / dtex and the elongation is 8.2%.
Met. Table 2 shows the evaluation results, fiber physical properties and the like.

Example 6 A spinning stock solution was prepared by the above method using a purified pulp manufactured by Nippon Paper Industries Co., Ltd. having a degree of polymerization of 520. At this time, 0.2% by mass of LiCl as a viscosity reducing additive was added to cellulose to prepare a spinning dope. As a result of confirming the cellulose concentration after adjusting the spinning solution, it was 14.9% by mass. The spinning dope thus obtained was discharged at 23.0 g / min by the above method, and the fiber obtained by spinning at a spinning speed of 400 m / min had a polymerization degree of 317.
The strength is 2.3 cN / dtex and the elongation is 9.9%.
Met. Table 2 shows the evaluation results, fiber physical properties and the like.

[0031]

[Table 2]

As shown in Table 2, when the raw material polymerization degree is 600 or more and the obtained fiber has a polymerization degree of 350 or more, it can be seen that the fiber properties are particularly excellent.

[0033]

EFFECTS OF THE INVENTION According to the present invention, it is possible to reduce the viscosity of a stock solution for spinning having a high cellulose concentration by using a raw material having a high degree of polymerization, so that spinning stability is not deteriorated even at a high spinning speed. It has become possible to greatly improve productivity.

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Claims (3)

[Claims] 1. A solution of a tertiary amine oxide of cellulose in L
A method for producing a solvent-spun cellulose fiber, which comprises spinning a spinning dope containing an i compound. 2. The concentration of cellulose contained in the spinning dope is 1
It is 0 mass% or more, The manufacturing method of the solvent spun cellulose fiber of Claim 1 characterized by the above-mentioned. 3. The degree of polymerization of cellulose is 600 or more,
The method for producing solvent-spun cellulose fibers according to claim 1 or 2, wherein the degree of polymerization of the obtained cellulose fibers is 350 or more.