TWI580829B - Manufacture of Cellulose Fibers - Google Patents

Description

Cellulose fiber manufacturing method

The present invention relates to a method of producing cellulosic fibers.

Conventionally, as cellulose fibers, regenerated cellulose fibers such as rayon fibers, rayon fibers, and Lyocell fibers have been known. However, rayon fibers must be prepared by dissolving the cellulose raw material with carbon disulfide, and the rayon fiber must be dissolved and regenerated using a solvent having a very high toxicity like a copper ammonia solution.

Further, Lyocell fibers are regenerated by dissolving cellulose by using N-methylmorpholine-N-oxide as a solvent, and N-methylmorpholine-N-oxide has a risk of bursting at 150 ° C. Etc., the manufacturing process is accompanied by danger.

Therefore, a method of producing cellulose fibers by using a highly toxic solvent such as carbon disulfide or a highly dangerous solvent such as N-methylmorpholine-N-oxide is reviewed.

As a method of producing a cellulose fiber, for example, a cellulose raw material such as wood pulp or cotton or cotton linters is dissolved in an ionic liquid composed of an imidazolium compound, and the obtained solution is extruded with the ionic liquid. A spinning method which is compatible with cellulose in an insoluble liquid to solidify it. In this method, as the ionic liquid composed of the aforementioned imidazolium compound, 1-butyl-3-methylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1-B is used. 3-methylimidazolium diethyl-phosphate, 1-ethyl- 3-methylimidazolium propionate ethyl ester, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, etc. (for example, refer to Patent Document 1, 2) .

[Advanced technical literature] [Patent Literature]

[Patent Document 1]

Japanese Special Publication 2008-248466

[Patent Document 2]

Japanese Special Open 2009-203467

However, when the method of using a cellulose raw material such as pulp or the like and an ionic liquid is used, since the spinnability is low, the melt spinning is used, and this method has a drawback that only a single fiber can be obtained. Also, in order to improve spinnability, dimethyl hydrazine (DMSO) has also been reviewed, but DMSO may have an adverse effect on the environment.

The present invention has an object of eliminating the above-mentioned disadvantages and providing a method for producing a cellulose fiber which has excellent spinnability and does not adversely affect the environment.

In order to achieve the above object, a method for producing a cellulose fiber of the present invention is characterized by comprising the steps of: dissolving a cellulose raw material in a step of obtaining a raw material solution from an ionic liquid composed of an imidazolium compound, and extruding the raw material solution into a coagulating liquid in which the imidazolium compound is soluble while cellulose is insoluble, so that the raw material solution is contained a step of solidifying the cellulose; wherein the cellulose raw material is 95% by mass or more based on the total cellulose, the degree of crystallization is 70% or more, and the average degree of polymerization of the cellulose is 1000 or more, and the step of obtaining the raw material solution In the middle, the cellulose raw material is dissolved until the average degree of polymerization becomes 300 to 4,300. Thus, a raw material solution excellent in spinnability can be obtained. Further, the average degree of polymerization of the cellulose raw material is the average degree of polymerization measured by the TAPPI method (viscosity method).

In the method for producing a cellulose fiber of the present invention, the cellulose raw material is a cellulose-containing material containing cellulose as a main component. When the content of the cellulose of the cellulose raw material is 95% by mass or more, the oil content or the inclusions such as lignin or hemicellulose are reduced, and the solubility or the stringiness at the time of spinning is not inhibited. Further, when the degree of crystallization of the cellulose raw material is 70% or more, a raw material solution having excellent spinnability can be obtained. When the average degree of polymerization of the cellulose portion of the cellulose raw material before being dissolved in the ionic liquid is less than 1,000, the strength of the obtained cellulose fiber is lowered.

When the degree of polymerization of the cellulose raw material after being dissolved in the ionic liquid is less than 300, the fiber may not be formed, and the strength of the cellulose fiber obtained by spinning may be lowered. When the degree of polymerization after dissolution exceeds 4,300, the viscosity of the raw material solution is increased, and the spinnability is lowered. Further, in the step of obtaining the raw material solution, the average degree of polymerization dissolved in the cellulose is 300 to 4,300, and the most suitable ion is selected depending on the average degree of polymerization of the cellulose raw material. The liquid can be adjusted by dissolving the dissolution time or the dissolution temperature as long as the raw material cellulose is dissolved to a desired average degree of polymerization. Examples of the ionic liquid composed of the imidazolium compound include 1-butyl-3-methylimidazolium acetate, 1,3-dimethylimidazolium acetate, and 1-ethyl-3-methylimidazole.鎓Diethyl-phosphate, ethyl 1-ethyl-3-methylimidazolium propionate, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium Acetate and the like. In particular, in the step of obtaining a raw material solution, in order to stably change the cellulose raw material to a desired average degree of polymerization, 1-allyl-3-methylimidazolium chloride can be suitably used as the imidazolium compound.

Further, when 1-allyl-3-methylimidazolium chloride is used as the ionic liquid, even a cellulose raw material having a high degree of polymerization can be easily dissolved to a desired average degree of polymerization. Further, the dissolving pulp or the absorbent cotton which is a cellulose raw material has a low degree of polymerization and a relatively low degree of polymerization, and it is easy to prepare a raw material solution, and can be suitably used. Here, the dissolving pulp is one in which high purity such as hemicellulose or lignin is removed, and the absorbent cotton is suitable for medical use.

In addition, as the cellulose raw material, even if the pulp or the absorbent cotton is dissolved, if the cellulose content or the like falls within the above range, it is needless to say that it can be used in the same manner. For example, a cellulose raw material obtained by recycling a cellulose fiber product or a cellulose raw material derived from agricultural waste can be used.

In the method for producing a cellulose fiber of the present invention, the coagulating liquid is preferably a water having a temperature ranging from 0 ° C to 100 ° C or a lower alcohol having a temperature ranging from -40 ° C to 100 ° C. When water is used as the coagulation liquid, the working environment is optimal, and when a lower alcohol is used, the spinnability can be improved. Also, the so-called lower alcohol is carbon number 1~5 Alcohol.

Next, embodiments of the present invention will be further described in detail with reference to the accompanying drawings.

The method for producing the cellulose fibers of the present embodiment can be carried out, for example, by the spinning device 1 shown in Fig. 1 .

The spinning device 1 includes a raw material solution container 3 supported by an arm 2a attached to the susceptor 2, and a raw material solution accommodated in the raw material solution container 3 supported by the arm 2b which is press-fitted to the susceptor 2. S piston 4. The piston 4 is free to move forward and backward via a cylinder that is not shown. The raw material solution S, for example, an ionic liquid composed of 1-allyl-3-methylimidazolium chloride, is heated at a temperature of 60 ° C, and is prepared by dissolving a cellulose raw material such as pulp or cotton wool in the ionic liquid. .

Here, when the cellulose raw material is dissolved in the ionic liquid, the cellulose-containing average polymerization degree of the cellulose raw material having an average polymerization degree of 1,000 or more is dissolved to 300 to 4,300. Therefore, the dissolution temperature is preferably from 30 ° C to 200 ° C. Further, the dissolution time is preferably from 0.5 hours to 30 hours.

Further, when the ionic liquid is 1-allyl-3-methylimidazolium chloride, the dissolution temperature is preferably from 30 ° C to 150 ° C. Further, the dissolution time is preferably from 0.5 hours to 20 hours.

Further, it is preferred to carry out such treatment by heating the raw material before dissolution to remove moisture, or by irradiating microwave or ultrasonic waves on the dissolved raw material solution to promote dissolution of the raw material.

Further, the spinning device 1 is provided with a coagulating liquid tank 5 in which 1-allyl-3-methylimidazolium chloride is contained and the coagulating liquid 6 in which cellulose is insoluble is contained. As the coagulation liquid 6, for example, water or a lower alcohol such as methanol, ethanol, propanol or butanol can be used.

According to the spinning device 1, the raw material solution S accommodated in the raw material solution container 3 is pressurized by the piston 4, and introduced into the coagulation liquid 6 accommodated in the coagulation liquid tank 5 through the conduit 7. A nozzle 8 is provided at the tip end portion of the conduit 7, and the raw material solution S is pressed from the nozzle 8 into the coagulation liquid 6.

For the extrusion of the raw material solution, a compressed gas or a single-screw kneading extruder, a twin-screw kneading extruder, a gear pump, or the like can be used. Further, the bubbles from the raw material solution are removed by a vacuum or centrifugal separation, stirring or the like to increase the spinnability.

The cellulose fiber F can be obtained by pressing the raw material solution S into the coagulation liquid 6. The 1-allyl-3-methylimidazolium chloride constituting the ionic liquid is soluble in the coagulation liquid 6, and since the cellulose is insoluble in the coagulation liquid 6, the cellulose in the raw material solution S solidifies. The conceptual diagram of the spinning by the wet spinning method in Fig. 1 may be performed by a dry-wet spinning method.

The cellulose fibers F are guided to the drying step 10 and dried by the rolls 5a, 5b, 5c provided in the coagulating liquid tank 5 and the rolls 9 provided outside the coagulating liquid tank 5. Further, the dried cellulose fibers F are wound on the winding rolls 11. The number of rolls provided in the coagulation liquid tank 5 is not limited to three, and one or more may be plural. Further, the rotational speed of each of the rolls may be the same speed, or the order of 5b is greater than 5a, and 5c is greater than 5b to accelerate the elongation of the fibers F.

The cross-sectional shape of the obtained fiber may be a circular shape, and the shape of the nozzle 8 may be changed into a triangular shape, a rhombus shape, an elliptical shape, a quadrangular shape, a flat shape, a star shape, or the like, and the cross-sectional shape of the obtained fiber may be changed. Give the fiber new properties. For example, the cross-sectional shape of the fiber can be modified by the shape of a triangle or a diamond to change the softness or feel of the fiber. Further, the heat insulating property can be improved by making the fibers hollow.

In the spinning apparatus 1, the raw material solution S which is maintained at a temperature range of 0 to 150 ° C is spun by being pressed into the coagulation liquid 6 at a pressing pressure in the range of 0.01 to 50 MPa. At this time, the nozzle 8 has a cross-sectional area in the range of 1 × 10 ^-5 to 100 mm ² .

The temperature of the coagulation liquid 6 is equal to or higher than the freezing point, and must be below the boiling point. The coagulating liquid 6 is maintained in the range of 0 ° C to 100 ° C in the case of water, and in the temperature range of -40 to 100 ° C in the case of the lower alcohol. When the coagulation liquid 6 is water, the temperature is frozen at less than 0 ° C, and it is vaporized when it exceeds 100 ° C. In any case, the cellulose cannot be fibrillated. Further, when the coagulation liquid 6 is a lower alcohol, the fluidity of the ionic liquid is lowered at a temperature of less than -40 ° C, and the cellulose cannot be fibrillated. When the coagulation liquid exceeds 100 ° C, the ionic liquid is rapidly dissolved in the coagulation liquid 6 because it is prematurely performed. The solidification of cellulose makes it difficult to cellulose cellulose. Further, in order to improve the spinnability, when the coagulation liquid 6 is water, the temperature is from 0 ° C to 70 ° C, and if it is a lower alcohol, it is preferably at a temperature lower than the boiling point by 20 ° C or higher.

Further, the cellulose fibers F solidified by the coagulating liquid 6 are wound on the winding rolls 11 at a speed of 1.0 to 1000 m/min.

As a result, cellulose fiber F can be obtained. The obtained cellulose fiber such as It is also necessary to carry out post-treatment according to an oil agent or a surfactant, a softener, a decane treatment agent, a texture modifier, an aqueous solution of an enzyme, a water-soluble resin, or a mixture thereof. The smoothness or softness is increased on the cellulose fibers F by post-treatment. Next, examples and comparative examples of the present invention are shown.

[Examples] [Example 1]

In this embodiment, first, an ionic liquid composed of 9.5 g of 1-allyl-3-methylimidazolium chloride is heated at a temperature of 60 ° C to dissolve 0.5 g of dissolving pulp (cellulose content of 95% by mass, The crystallization degree was 75%, and the average degree of polymerization measured by the TAPPI standard method was 1050. On the ionic liquid, a raw material solution S having a concentration of 5 mass% was prepared.

In addition, the average degree of polymerization in the present specification refers to the average degree of polymerization of the viscosity, and is described in the "Cellular Code" (new edition, edited by the Institute of Cellulose, Asakura Shoten, March 2008, p. 79-80). Measured by the TAPPI standard method.

The above-mentioned dissolving pulp was measured by visual observation for a period of 3.0 hours after the ionic liquid was completely dissolved. Further, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer and was 700 mPa. second. The results are shown in Table 1.

Next, the cellulose fiber F was spun in the spinning apparatus 1 shown in Fig. 1 by using the raw material solution S obtained in the present example. The spinning conditions were a temperature of the raw material solution S of 60 ° C, an extrusion pressure of 1.5 MPa, a temperature of the coagulating liquid 6 (water) of 60 ° C, a cross-sectional area of the nozzle 8 of 1.77 × 10 ^-2 mm ² , and a winding speed of 160 m / min.

As a result, cellulose fiber F having good spinnability can be obtained.

The spinnability of the cellulose fibers F obtained in this example is shown in Table 1.

[Example 2]

In the present embodiment, the raw material solution was prepared in the same manner as in Example 1 except that the absorbent fiber was used as the cellulose raw material (the cellulose content was 99% by mass, the degree of crystallization was 80%, and the average degree of polymerization measured by the TAPPI method was 1,500). S.

The time until the above-mentioned defatted cotton was completely dissolved in the ionic liquid was visually measured and was 4.0 hours. Moreover, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer, which was 750 mPa. second. The results are shown in Table 1.

Next, the raw material solution S obtained in Example 2 was used, except that the winding speed was the same as in Example 1, and the cellulose fiber F was spun. As a result, cellulose fiber F having good spinnability can be obtained.

The spinnability of the cellulose fibers F obtained in this example is shown in Table 1.

[Example 3]

In this example, 1-ethyl-3-methylimidazolium acetate was used as the ionic liquid, except that the heat treatment temperature was 120 ° C, and other examples 1 The raw material solution S is prepared exactly the same.

The time from the dissolution of the pulp to the complete dissolution of the ionic liquid was visually determined to be 1.5 hours. Further, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer and was 700 mPa. second. The results are shown in Table 1.

Next, using the raw material solution S obtained in Example 3, except that the winding speed was the same as in Example 1, the cellulose fiber F was spun. As a result, cellulose fiber F having good spinnability can be obtained.

The spinnability of the cellulose fibers F obtained in this example is shown in Table 1.

[Comparative Example 1]

In this comparative example, the same preparation as in Example 1 was carried out except that the undefatted cotton (cellulose content: 94% by mass, degree of crystallization 70%, average degree of polymerization measured by the TAPPI method of 5,500) was used as the cellulose raw material. Raw material solution S.

The above-mentioned cotton was measured by visual observation at a time until the ionic liquid was completely dissolved, and it was 10.0 hours.

Further, the raw material solution S was gel-like at 60 ° C, and the viscosity measurement could not be performed. The results are shown in Table 1.

Next, the raw material solution S obtained in the present comparative example was completely the same as Example 1 except for the winding speed, and the spinning apparatus 1 tried the spinning of the cellulose fibers F as shown in Fig. 1, because of the high viscosity, it was often Fiber breakage occurred and it was impossible to spin. The results are shown in Table 1.

[Comparative Example 2]

In this comparative example, in addition to using defatted Lamy (cellulose content 80% by mass, degree of crystallization 68%, average degree of polymerization measured by the TAPPI method of 2300) as a cellulose raw material, other examples and examples 1 The raw material solution S is prepared exactly the same.

The aforementioned absorbent cotton was measured by visual observation for a period of 6.0 hours after the ionic liquid was completely dissolved.

Further, the raw material solution S was gel-like at 60 ° C, and the viscosity measurement could not be performed. The results are shown in Table 1.

Next, the raw material solution S obtained in the present comparative example was completely the same as Example 1 except for the winding speed, and the spinning apparatus 1 tried the spinning of the cellulose fibers F as shown in Fig. 1, because of the high viscosity, it was often Fiber breakage occurred and it was impossible to spin. The results are shown in Table 1.

[Comparative Example 3]

In the present comparative example, the raw material solution S was prepared in the same manner as in Example 1 except that 1-ethyl-3-methylimidazolium chloride was used as the ionic liquid.

The dissolving pulp was heat-treated in the same manner as in Example 1 in the above-mentioned dissolving pulp for 3.0 hours. Moreover, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer, which was 1200 mPa. second. The results are shown in Table 1.

Next, using the raw material solution S obtained in the comparative example, the winding speed is removed. The spinning of the cellulose fibers F was carried out in the spinning apparatus 1 as shown in Fig. 1 except that the same as in the first embodiment. Spinning is possible, and when the winding speed is faster than 38.5 m/min, fiber breakage often occurs, and the spinnability is poor. The results are shown in Table 1.

[Comparative Example 4]

In the present comparative example, the raw material solution S was prepared in the same manner as in Example 1 except that the ionic liquid composed of 1-butyl-3-methylimidazolium chloride was used.

The dissolving pulp was heat-treated in the same manner as in Example 1 in the above-mentioned dissolving pulp for 3.0 hours. Moreover, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer, which was 1400 mPa. second. The results are shown in Table 1.

Next, the raw material solution S obtained in the present comparative example was completely the same as in Example 1 except for the winding speed, and the spinning of the cellulose fibers F was performed in the spinning apparatus 1 as shown in Fig. 1 . Spinning is possible, and when the winding speed is faster than 23.5 m/min, fiber breakage often occurs, and the spinnability is poor. The results are shown in Table 1.

[Comparative Example 5]

In the present comparative example, the raw material solution S was prepared in the same manner as in Example 2 except that 1-ethyl-3-methylimidazolium chloride was used as the ionic liquid.

The aforementioned defatted cotton is as small as 4.0 in the same manner as in the second embodiment. Heat treatment is performed at the time. Moreover, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer, which was 1400 mPa. second. The results are shown in Table 1.

Next, the raw material solution S obtained in the present comparative example was completely the same as in Example 1 except for the winding speed, and the spinning of the cellulose fibers F was performed in the spinning apparatus 1 as shown in Fig. 1 . Spinning is possible, and when the winding speed is faster than 32.4 m/min, fiber breakage often occurs, and the spinnability is poor. The results are shown in Table 1.

[Comparative Example 6]

In the present comparative example, the raw material solution S was prepared in the same manner as in Example 2 except that the ionic liquid was composed of an ionic liquid composed of 1-butyl-3-methylimidazolium chloride.

The absorbent cotton was heat-treated in the same manner as in Example 2 in the above-mentioned absorbent liquid for 4.0 hours. Moreover, the viscosity of the raw material solution S at 60 ° C was measured using a vibrating viscometer, which was 1500 mPa. second. The results are shown in Table 1.

Next, the raw material solution S obtained in the present comparative example was completely the same as in Example 1 except for the winding speed, and the spinning of the cellulose fibers F was performed in the spinning apparatus 1 as shown in Fig. 1 . Spinning is possible, and when the winding speed is faster than 18.2 m/min, fiber breakage often occurs, and the spinnability is poor. The results are shown in Table 1.

[Comparative Example 7]

In this comparative example, the same raw material solution as in Example 2 was prepared except that the ionic liquid was heat-treated at 120 ° C for 4.5 hours. S.

The viscosity of the raw material solution S at 60 ° C was measured by a vibrating viscometer and was 280 mPa. second. The results are shown in Table 1.

Next, using the raw material solution S obtained in the present comparative example, the spinning of the cellulose fibers F was attempted in the spinning apparatus 1 as shown in Fig. 1, because the fibers were too low to form the fibers. The results are shown in Table 1.

Also, in the table, AmimCl is represented by 1-allyl-3-methylimidazolium chloride, EmimAc is represented by 1-ethyl-3-methylimidazolium acetate, and EmimCl is represented by 1-ethyl- 3-methylimidazolium chloride, BmimCl is represented by 1-butyl-3-methylimidazolium chloride.

Further, in the table, the highest winding speed is expressed as the highest speed at which the wire which is not cut for 10 minutes can be wound. As a winding speed, the wire has a low practical utility at 100 m/min or less. Therefore, as the evaluation of the spinnability, the speed of each of 100 m/min or more is ○, and the spinning may be performed, but the maximum winding speed is less than 100 m/min, and the winding is not X.

Table 1 shows dissolved pulp or cotton, and 1-allyl, based on a cellulose raw material containing 95% by mass or more of cellulose, 70% or more of crystallinity, and an average degree of polymerization of 1,000 or more as measured by the TAPPI method. The combination of the ionic liquid composed of -3-methylimidazolium chloride can obtain the raw material solution S in a short time, and it is very clear that a cellulose fiber having good spinnability can be obtained. Further, when the ionic liquid composed of 1-ethyl-3-methylimidazolium acetate is combined with the cellulose raw material having a relatively low degree of polymerization such as dissolving pulp, the raw material solution S can be obtained in a short time. It is very clear that a cellulose fiber having good spinnability can be obtained.

On the other hand, in the combination of the above-mentioned cellulose raw material other than the dissolving pulp or the absorbent cotton and the ionic liquid composed of 1-allyl-3-methylimidazolium chloride (Comparative Examples 1, 2), the fiber cutting often occurs. Broken spinning itself is not clear.

Further, the aforementioned dissolving pulp or cotton wool and 1-allyl-3-methylimidazole The combination of ionic liquids composed of other imidazolium compounds other than ruthenium chloride (Comparative Examples 3 to 6) was unclear in spinnability.

Further, in the above-mentioned combination of the dissolving pulp or the ionic liquid composed of the 1-allyl-3-methylimidazolium chloride (Comparative Example 7), the excess polymerization process is because of the cellulose polymerization degree of the raw material solution. Too low, the spinnability deteriorates to be clear.

When 1-ethyl-3-methylimidazolium chloride is used as the ionic liquid, the dissolution state of the raw material solution is not treated when the raw material is heat-treated with 1-allyl-3-methylimidazolium chloride under the same conditions. It has a uniform and high viscosity, and the spinning speed of the spinnable yarn is 32.4 to 38.5 m/min or more. Since the fiber is cut, the spinnability is poor, and the practical cellulose fiber cannot be obtained.

When 1-butyl-3-methylimidazolium chloride is used as the ionic liquid, the dissolution state of the raw material solution is not changed when the raw material is heat-treated under the same conditions as 1-allyl-3-methylimidazolium chloride. It is uniform and has a high viscosity. When the winding speed of the spinner is 18.2 to 23.5 m/min or more, the spinnability is poor because the fiber is cut, and thus practical cellulose fibers cannot be obtained.

Further, the fiber diameter of the spun fiber was measured by a scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.), and the fiber diameters of the fibers obtained in Examples 1, 2, and 3 were 25.2 μm, 28.4 μm, and 25.6 μm, respectively. . Here, the fiber diameters of the fibers obtained in Comparative Examples 3 to 6 which are possible for spinning were 39.2 μm, 46.5 μm, 41.1 μm, and 51.2 μm, respectively. Comparative Examples 3 to 6 are possible for spinning, as obtained by the examples. The fiber diameter of the fiber is larger. If the fiber diameter is larger, when it is softened into silk, it cannot be a practical fiber because of lack of flexibility.

Cellulose fibers are spun, and it is necessary to dissolve not only the cellulose raw material in the ionic liquid but also an average degree of polymerization of 300 or more. When the average degree of polymerization is 300 or less, the fibers become brittle, so the cutting of the fibers often occurs.

As is apparent from the results of Table 1, when the 1-allyl-3-methylimidazolium chloride was used, the viscosity of the solution after the cellulose raw material was dissolved was lowered as compared with the case of using other ionic liquids, and the spinnability was excellent. Therefore, if 1-allyl-3-methylimidazolium chloride is used, even if it is a polymer cellulose raw material, there is a possibility that it can be used as a cellulose raw material solution which is possible to be spun.

Therefore, the dissolution of the cellulose raw material is analyzed by changing the temperature conditions using the raw material solution of the previously known average polymerization degree. As a control, the dissolution and decomposition of the cellulose raw material were compared with 1-ethyl-3-methylimidazolium acetate.

When the cellulose having an average polymerization degree of 9000 was used as the raw material in Table 2, the analysis results when cellulose having an average polymerization degree of 1500 was used as the raw material in Table 3 was used.

Using a cotton fiber having an average degree of polymerization of 9000 as a raw material and a cotton wool having an average degree of polymerization of 1,500, a raw material solution having a cellulose concentration of 5% (ionic liquid: 9.5 g, cellulose: 0.5 g) was prepared to carry out dissolution analysis. Further, the measurement of the average degree of polymerization was carried out in the same manner as described above by the TAPPI method.

Further, in the case where the average degree of polymerization is plotted, it is indicated that the cellulose raw material has been dissolved by visual observation.

In addition, the average degree of polymerization of the cellulose containing the cellulose raw material means that the cellulose of the solid is dissolved, and the degree of polymerization is measured by the TAPPI method. It means the average degree of polymerization of the raw materials themselves. For example, in Table 2, cellulose having an average degree of polymerization of 9000 is used as a raw material. Moreover, the average degree of polymerization after the treatment of the ionic liquid refers to the average degree of polymerization after the ionic liquid is dissolved in the raw material cellulose. Spinning is possible in the range of 300 to 4300 in the average degree of polymerization after the ionic liquid is dissolved.

As is clear from Table 2 and Table 3, in the case where the cellulose raw material was dissolved with 1-allyl-3-methylimidazolium chloride, the average degree of polymerization of the raw material drastically decreased with the passage of time. In the case where 1-ethyl-3-methylimidazolium acetate was used, no significant decrease in molecular weight was observed.

Thus, it is believed that 1-ethyl-3-methylimidazolium acetate may cause hydrogen bond cleavage between the cellulose partial daughter strands, 1-allyl-3-methylimidazolium chloride The compound is cleaved by a covalent bond between the glucose constituting the cellulose as the hydrogen bond is cut.

As shown in Table 2, when EmimAc was used, dissolution was visually confirmed at 120 ° C for 12 hours, and the average degree of polymerization at this time was 7,200. However, this raw material solution has a high viscosity and is therefore poor in spinnability. On the other hand, the raw material solution was treated with AmimCl at 120 ° C for 6 hours, and the average degree of polymerization was 4,100, and the spinnability was good. When the average degree of polymerization of other solids is also 4,300 or more, the viscosity becomes high and the spinnability is poor, and the average degree of polymerization is confirmed to be 4,300, which is a good spinning possibility.

Therefore, the cellulose fiber is spun, and it is necessary to dissolve not only the cellulose raw material in the ionic liquid but also the low molecular weight of the average polymerization degree of 300 to 4,300. As described above, if the average degree of polymerization is 300 or less, the fibers become brittle, Therefore, the cutting of the fiber often occurs. When the average degree of polymerization is 4,300 or more, the spinnability is poor because the viscosity of the raw material solution is high.

As shown in Table 2, when using 1-allyl-3-methylimidazolium chloride, even when a high molecular weight cellulose raw material is used as a raw material, the average polymerization degree to the spinning may be 300 in a relatively short time. The cellulose partial chain was cut off to the extent of ~4300. For example, by treating at 120 ° C for 6 hours, the average degree of polymerization becomes 4,100, and a possible raw material solution for spinning can be obtained.

On the other hand, when 1-ethyl-3-methylimidazolium acetate is used, the average degree of polymerization is 7200 even when heated at 120 ° C for 12 hours, because the viscosity of the raw material solution is high, and the spinnability is good. Fiber is difficult. Thus, when treated with 1-ethyl-3-methylimidazolium acetate, the cellulose is cut at the time of the average degree of polymerization possible, and it is necessary to treat it at a high temperature for a long time.

Further, as shown in Table 3, when a low molecular weight cellulose raw material having a small average degree of polymerization was used, when 1-allyl-3-methylimidazolium chloride was used, it was treated at 60 ° C for 6 hours to make it not low molecularly. It is possible to dissolve such cellulose.

From the above analysis results, if 1-allyl-3-methylimidazolium chloride is used, even when a high molecular weight cellulose raw material having an average polymerization degree of 4300 or more is used, heating is performed at about 70 ° C or higher. The low molecular weight of the fiber to the possible molecular weight of the spinning, and as a result, a low viscosity cellulose raw material solution can be prepared.

Further, when a low molecular weight cellulose raw material having an average polymerization degree of less than 4,300 is used, it is possible to dissolve the cellulose raw material without lowering the molecular weight by heating at a temperature of about 70 ° C or less.

Further, dissolving cellulose with 1-allyl-3-methylimidazolium chloride In the case of a raw material, it is also possible to suppress the reduction in molecular weight by heating and dissolving in a nitrogen atmosphere.

Thus, by using 1-allyl-3-methylimidazolium chloride, the average degree of polymerization of the cellulose raw material can be easily adjusted to suit the spinning by adjusting the heating temperature, the treatment time, and the environment. Raw material solution.

As described above, 1-allyl-3-methylimidazolium chloride is compared with other ionic liquids, because the cellulose fraction has a low molecular weight property, and even a high molecular cellulose material can be low molecular. It is converted to a molecular weight that can be spun. Further, the cellulose raw material can be dissolved in a short period of time at a relatively low temperature as compared with other ionic liquids, and it can be a raw material solution excellent in spinnability. Therefore, it is safe to work well, and the cost required for heating is also less than that of other ionic liquids.

1‧‧‧Spinning device

2‧‧‧Base

5‧‧‧ coagulation tank

6‧‧‧Condensate

7‧‧‧ catheter

8‧‧‧ nozzle

10‧‧‧ drying step

S‧‧‧ raw material solution

[figure 1]

An explanatory cross-sectional view showing one configuration example of a spinning apparatus used in the production method of the present invention.

Claims (7)

A method for producing a cellulose fiber, comprising the steps of: dissolving a cellulose raw material in an ionic liquid composed of an imidazolium compound to obtain a raw material solution, and extruding the raw material solution into the imidazolium compound a step of solidifying cellulose in an insoluble coagulating liquid to solidify the cellulose contained in the raw material solution; characterized in that the cellulose raw material is 95% by mass or more based on the total cellulose, and the degree of crystallization is 70% or more, the average degree of polymerization of cellulose is 1000 or more, and the imidazolium compound is 1-allyl-3-methylimidazolium chloride, and in the step of obtaining the raw material solution, the dissolution temperature is 30 to 60. The cellulose raw material was dissolved at ° C until the average degree of polymerization became 300 to 4,300. The method for producing a cellulose fiber according to the first aspect of the invention, wherein the raw material solution has a viscosity at 60 ° C of 700 to 750 mPa ‧ seconds. The method for producing a cellulose fiber according to claim 1 or 2, wherein the cellulose raw material is a dissolving pulp or a cotton wool. The method for producing a cellulose fiber according to any one of claims 1 to 2, wherein the coagulating liquid is water having a temperature in the range of 0 to 100 °C. The method for producing a cellulose fiber according to the third aspect of the invention, wherein the coagulating liquid is water having a temperature range of 0 to 100 °C. The method for producing a cellulose fiber according to any one of claims 1 to 2, wherein the coagulating liquid is a lower alcohol in a temperature range of -40 to 100 °C. The method for producing a cellulose fiber according to the third aspect of the invention, wherein the coagulating liquid is a lower alcohol in a temperature range of -40 to 100 °C.