JPWO2014024260A1 - Method for producing cellulose fiber - Google Patents

Abstract

A method for producing a cellulose fiber having excellent spinnability is provided. A cellulose raw material is dissolved in an ionic liquid composed of an imidazolium compound until an average polymerization degree of 300 to 4300 is obtained to obtain a raw material solution (S), and then the raw material solution (S) is dissolved in the imidazolium compound and cellulose It is extruded into an insoluble coagulation liquid (6) to coagulate the cellulose contained in the raw material solution (S). The cellulose raw material contains 95% by mass or more of cellulose with respect to the total amount, has a crystallinity of 70% or more and an average polymerization degree measured by the TAPPI method of 1000 or more.

Description

  The present invention relates to a method for producing cellulose fibers.

  Conventionally, regenerated cellulose fibers such as rayon fiber, cupra fiber, and lyocell fiber are known as cellulose fibers. However, it is necessary to regenerate the rayon fiber by dissolving the cellulose raw material with carbon disulfide and the cupra fiber with a highly toxic solvent such as a copper ammonia solution.

  In addition, lyocell fiber is regenerated by dissolving cellulose using N-methylmorpholine-N-oxide as a solvent, but N-methylmorpholine-N-oxide is dangerous in the production process, such as the danger of explosion at 150 ° C. Is accompanied.

  Therefore, a method for producing cellulose fibers without using a highly toxic solvent such as carbon disulfide or a highly dangerous solvent such as N-methylmorpholine-N-oxide has been studied.

  As a method for producing cellulose fibers, for example, cellulose raw materials such as wood pulp, cotton, and cotton linter are dissolved in an ionic liquid composed of an imidazolium compound, and the obtained solution is compatible with the ionic liquid and insoluble in cellulose. A method of coagulating and spinning by extruding into a liquid is known. In this method, as the ionic liquid comprising the imidazolium compound, 1-butyl-3-methylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-butyl-3-methylimidazolium acetate, Ethyl-3-methylimidazolium propionate, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate and the like are used (for example, see Patent Documents 1 and 2).

JP 2008-248466 A JP 2009-203467 A

  However, in the method using a cellulose raw material and an ionic liquid such as pulp, melt blow spinning is used because of low spinnability, but this method has a disadvantage that only a single fiber can be obtained. In order to improve the spinnability, a method using dimethyl sulfoxide (DMSO) has also been studied. However, DMSO may adversely affect the environment.

  An object of the present invention is to provide a method for producing a cellulose fiber that eliminates such inconvenience, has excellent spinnability, and has no risk of adversely affecting the environment.

  In order to achieve this object, the cellulose fiber production method of the present invention comprises a step of dissolving a cellulose raw material in an ionic liquid composed of an imidazolium compound to obtain a raw material solution, and the raw material solution is soluble in the imidazolium compound. And a step of coagulating the cellulose contained in the raw material solution by extruding into a coagulating liquid in which the cellulose is insoluble, and the cellulose raw material contains 95% by mass or more of cellulose with respect to the total amount. And the crystallinity is 70% or more, the average polymerization degree of the contained cellulose is 1000 or more, and in the step of obtaining the raw material solution, the cellulose raw material is dissolved until the average polymerization degree is 300 to 4300. To do. Thereby, the raw material solution excellent in spinnability can be obtained. The average degree of polymerization of the cellulose raw material is an average degree of polymerization measured by the TAPPI method (viscosity method).

  In the method for producing cellulose fibers of the present invention, the cellulose raw material is a cellulose-containing material containing cellulose as a main component. When the cellulose content of the cellulose raw material is 95% by mass or more, there are few contaminants such as fats and oils, lignin, hemicellulose, etc., and the solubility and spinnability during spinning are not hindered. Moreover, the raw material solution which has the outstanding spinnability can be obtained as the crystallinity degree of a cellulose raw material is 70% or more. When the average degree of polymerization of the cellulose content of the cellulose raw material before being dissolved in the ionic liquid is less than 1000, the strength of the resulting cellulose fiber is lowered.

  If the degree of polymerization after dissolution in an ionic liquid of cellulose raw material is less than 300, fiber formation may not be possible, and even if the fiber is spun, the strength of the cellulose fiber obtained is lowered. If the degree of polymerization after dissolution exceeds 4300, the viscosity of the raw material solution increases and spinnability is reduced. In addition, in the step of obtaining the raw material solution, in order to dissolve the average polymerization degree of cellulose to 300 to 4300, an optimal ionic liquid is selected and the dissolution time and the dissolution temperature are adjusted depending on the average polymerization degree of the cellulose raw material Thus, the raw material cellulose may be dissolved until the desired average degree of polymerization is reached. Examples of ionic liquids composed of imidazolium compounds include 1-butyl-3-methylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methyl. Examples include imidazolium propionate, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate and the like. In particular, in the step of obtaining the raw material solution, 1-allyl-3-methylimidazolium chloride can be suitably used as the imidazolium compound in order to stably bring the cellulose raw material to a desired average degree of polymerization.

  When 1-allyl-3-methylimidazolium chloride is employed as the ionic liquid, a cellulose raw material having a high degree of polymerization can be easily dissolved so as to have a desired average degree of polymerization. In addition, dissolving pulp and cotton wool as the cellulose raw material have few impurities and have a relatively low degree of polymerization. Therefore, it is easy to prepare a raw material solution and can be suitably used. Here, it is suitable that the dissolving pulp has a high purity excluding hemicellulose, lignin and the like, and that the absorbent cotton is used for medical purposes.

  In addition, it cannot be overemphasized that even if it is a cellulose raw material other than melt | dissolution pulp or absorbent cotton, as long as a cellulose content etc. belong to the said range, it can use similarly. For example, a cellulose raw material obtained by recycling a cellulose fiber product, a cellulose raw material derived from agricultural waste, or the like can be used.

  In the method for producing cellulose fiber of the present invention, the coagulation liquid is preferably water having a temperature in the range of 0 ° C to 100 ° C or a lower alcohol having a temperature in the range of -40 ° C to 100 ° C. If water is used as the coagulation liquid, it is preferable from the working environment, and if lower alcohol is used, the spinnability can be improved. In addition, a lower alcohol means a C1-C5 alcohol.

Explanatory sectional drawing which shows the example of 1 structure of the spinning apparatus used for the manufacturing method of this invention.

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

  The manufacturing method of the cellulose fiber of this embodiment can be implemented, for example with the spinning apparatus 1 shown in FIG.

  The spinning device 1 includes a raw material solution container 3 supported by an arm 2 a attached to a base 2, and a raw material solution S supported by an arm 2 b attached to the base 2 and accommodated in the raw material solution container 3. And a piston 4 for pressurizing. The piston 4 is movable forward and backward by a cylinder (not shown). The raw material solution S is prepared, for example, by heating an ionic liquid composed of 1-allyl-3-methylimidazolium chloride to a temperature of 60 ° C. and dissolving a cellulose raw material such as dissolving pulp or absorbent cotton in the ionic liquid. .

  Here, when melt | dissolving a cellulose raw material in an ionic liquid, it melt | dissolves until the average polymerization degree of the cellulose containing the cellulose raw material of average polymerization degree 1000 or more will be set to 300-4300. For this purpose, the melting temperature is preferably 30 ° C to 200 ° C. The dissolution time is preferably 0.5 hours to 30 hours.

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

  In addition, the raw material is heated before melting to remove moisture, or the raw material solution is irradiated with microwaves or ultrasonic waves during melting, so that the melting of the raw material is promoted. It is preferable.

  The spinning device 1 includes a coagulating liquid tank 5, which contains a coagulating liquid 6 in which 1-allyl-3-methylimidazolium chloride is soluble and insoluble in cellulose. Yes. As the coagulating liquid 6, for example, water or lower alcohol such as methanol, ethanol, propanol, butanol or the like 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 coagulating liquid 6 accommodated in the coagulating liquid tank 5 through the conduit 7. A nozzle 8 is provided at the tip of the conduit 7, and the raw material solution S is pushed out from the nozzle 8 into the coagulation liquid 6.

  For extruding 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. In addition, spinnability can be increased by removing bubbles from the raw material solution by a process such as vacuum, centrifugation, or stirring.

  Cellulose fiber F can be obtained by extruding the raw material solution S to the coagulating liquid 6. Since 1-allyl-3-methylimidazolium chloride constituting the ionic liquid is soluble in the coagulating liquid 6, cellulose is insoluble in the coagulating liquid 6, so that the cellulose in the raw material solution S coagulates. It is. Although FIG. 1 shows a conceptual diagram of spinning by a wet spinning method, spinning may be performed by a dry and wet spinning method.

  The cellulose fibers F are guided to the drying step 10 by the rolls 5a, 5b, 5c provided in the coagulating liquid tank 5 and the roll 9 provided outside the coagulating liquid tank 5, and dried. Furthermore, the cellulose fiber F after drying is wound up on the winding roll 11. The number of rolls installed in the coagulating liquid tank 5 is not limited to three, and may be one or plural. Moreover, the rotational speed of each roller may be the same, but the fibers F may be stretched by sequentially increasing the speed from 5b to 5b to 5b.

  The cross-sectional shape of the obtained fiber may be circular, but by changing the shape of the nozzle 8 to various shapes such as a triangle, a rhombus, an ellipse, a quadrangle, a flat shape, and a star shape, the cross-sectional shape of the obtained fiber is changed, New properties can be imparted to the fiber. For example, by making the cross-sectional shape of the fiber a triangle or a rhombus, the flexibility and feel of the fiber can be improved. Moreover, heat insulation can be improved by making a fiber hollow.

In the spinning device 1, the raw material solution S maintained at a temperature in the range of 0 to 150 ° C. can be spun by extruding it into the coagulation liquid 6 with a 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 must be above the freezing point and below the boiling point, but the coagulation liquid 6 is in the range of 0 to 100 ° C. for water and in the range of −40 to 100 ° C. for lower alcohols. Is kept at a temperature of When the coagulating liquid 6 is water, it freezes when its temperature is less than 0 ° C., and vaporizes when the temperature exceeds 100 ° C., and in any case, cellulose cannot be made into fibers. Further, when the coagulation liquid 6 is a lower alcohol, if the temperature is lower than −40 ° C., the fluidity of the ionic liquid is lowered, and cellulose cannot be fibrillated. Dissolves quickly in the coagulation liquid 6 and the coagulation of cellulose proceeds prematurely, making it difficult to fiberize cellulose. In order to improve the spinnability, when the coagulation liquid 6 is water, it is kept at a temperature of 0 ° C. to 70 ° C., and when it is a lower alcohol, it is kept above the freezing point and at a temperature lower than the boiling point by 20 ° C. or more. It is preferable.

  Moreover, the cellulose fiber F coagulated with the coagulating liquid 6 is wound up on the winding roll 11 at a speed of 1.0 to 1000 m / min.

  As a result, the cellulose fiber F can be obtained. The obtained cellulose fiber may be post-treated with an oil agent, a surfactant, a softening agent, a silicone treating agent, a texture improving agent, an aqueous enzyme solution, a water-soluble resin, or a mixture thereof as necessary. Smoothness and flexibility are added to the cellulose fiber F by the post-treatment. Next, examples and comparative examples of the present invention are shown.

[Example 1]
In this example, first, 9.5 g of ionic liquid composed of 1-allyl-3-methylimidazolium chloride was heated to a temperature of 60 ° C., and dissolved pulp (cellulose content 95 mass%, crystallinity) was added to the ionic liquid. A raw material solution S having a concentration of 5% by mass was prepared by dissolving 0.5 g of 75%, an average degree of polymerization 1050) measured by the TAPPI standard method.

  In the present specification, the average degree of polymerization refers to the viscosity average degree of polymerization, and TAPPI described in “Encyclopedia of Cellulose” (new edition, edited by Cellulose Society, Asakura Shoten, March 2008, p. 79-80). The one measured according to the standard method.

  It was 3.0 hours when the time until the dissolving pulp was completely dissolved in the ionic liquid was measured by visual observation. Moreover, it was 700 mPa * sec when the viscosity at 60 degrees C of the raw material solution S was measured using the vibration viscometer. The results are shown in Table 1.

Next, using the raw material solution S obtained in this example, cellulose fiber F was spun by the spinning device 1 shown in FIG. The spinning conditions were: raw material solution S temperature 60 ° C., extrusion pressure 1.5 MPa, coagulating liquid 6 (water) temperature 60 ° C., nozzle 8 cross-sectional area 1.77 × 10 ⁻² mm ² , winding speed 160 m / min. It was.

  As a result, cellulose fiber F could be obtained with good spinnability. The spinnability of the cellulose fiber F obtained in this example is shown in Table 1.

[Example 2]
In this example, the raw material solution S was exactly the same as Example 1 except that absorbent cotton (cellulose content 99% by mass, crystallinity 80%, average polymerization degree 1500 measured by the TAPPI method) was used as the cellulose raw material. Was prepared.

  It was 4.0 hours when the time until the absorbent cotton was completely dissolved in the ionic liquid was measured by visual observation. Moreover, it was 750 mPa * second when the viscosity at 60 degrees C of the raw material solution S was measured using the vibration viscometer. The results are shown in Table 1.

  Next, using the raw material solution S obtained in Example 2, the cellulose fiber F was spun in the same manner as in Example 1 except for the winding speed. As a result, cellulose fiber F could be obtained with good spinnability. The spinnability of the cellulose fiber 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, and the raw material solution S was prepared exactly as in Example 1 except that the heat treatment temperature was 120 ° C.

  When the time until the dissolving pulp was completely dissolved in the ionic liquid was measured by visual observation, it was 1.5 hours. Moreover, it was 700 mPa * sec when the viscosity at 60 degrees C of the raw material solution S was measured using the vibration viscometer. The results are shown in Table 1.

  Next, using the raw material solution S obtained in Example 3, the cellulose fiber F was spun in the same manner as in Example 1 except for the winding speed. As a result, cellulose fiber F could be obtained with good spinnability. The spinnability of the cellulose fiber F obtained in this example is shown in Table 1.

[Comparative Example 1]
In this comparative example, it was exactly the same as Example 1 except that non-defatted cotton (cellulose content 94 mass%, crystallinity 70%, average polymerization degree 5500 measured by TAPPI method) was used as the cellulose raw material. A raw material solution S was prepared.

  When the time until the cotton was completely dissolved in the ionic liquid was measured by visual observation, it was 10.0 hours. Moreover, the raw material solution S was a gel form at 60 ° C., and the viscosity could not be measured. The results are shown in Table 1.

  Next, the raw material solution S obtained in this comparative example was used, and the spinning of the cellulose fiber F was attempted with the spinning device 1 shown in FIG. Due to the viscosity, the fiber was frequently cut and could not be spun. The results are shown in Table 1.

[Comparative Example 2]
In this comparative example, a raw material solution was made exactly the same as Example 1, except that defatted ramie (cellulose content 80% by mass, crystallinity 68%, average polymerization degree 2300 measured by TAPPI method) was used as the cellulose raw material. S was prepared.

  It was 6.0 hours when the time until the absorbent cotton was completely dissolved in the ionic liquid was measured visually. Moreover, the raw material solution S was a gel form at 60 ° C., and the viscosity could not be measured. The results are shown in Table 1.

  Next, the raw material solution S obtained in this comparative example was used, and the spinning of the cellulose fiber F was attempted with the spinning device 1 shown in FIG. Due to the viscosity, the fiber was frequently cut and could not be spun. The results are shown in Table 1.

[Comparative Example 3]
In this comparative example, a raw material solution S was prepared exactly 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 ionic liquid for 3.0 hours as in Example 1. Moreover, it was 1200 mPa * second when the viscosity at 60 degrees C of the raw material solution S was measured using the vibration viscometer. The results are shown in Table 1.

  Next, using the raw material solution S obtained in this comparative example, the cellulose fiber was spun by the spinning device 1 shown in FIG. Although spinning was possible, when the winding speed was higher than 38.5 m / min, the fiber was frequently cut and the spinnability was poor. The results are shown in Table 1.

[Comparative Example 4]
In this comparative example, a raw material solution S was prepared in exactly the same manner as in Example 1 except that an ionic liquid composed of 1-butyl-3-methylimidazolium chloride was used.

  The dissolving pulp was heat-treated in the ionic liquid for 3.0 hours in the same manner as in Example 1. Further, the viscosity of the raw material solution S at 60 ° C. was measured using a vibration viscometer, and it was 1400 mPa · sec. The results are shown in Table 1.

  Next, using the raw material solution S obtained in this comparative example, the cellulose fiber was spun by the spinning device 1 shown in FIG. Although spinning was possible, when the winding speed was higher than 23.5 m / min, the fiber was frequently cut and the spinnability was poor. The results are shown in Table 1.

[Comparative Example 5]
In this comparative example, a raw material solution S was prepared in exactly the same manner as in Example 2, except that 1-ethyl-3-methylimidazolium chloride was used as the ionic liquid.

  The absorbent cotton was heated in the ionic liquid for 4.0 hours in the same manner as in Example 2. Further, the viscosity of the raw material solution S at 60 ° C. was measured using a vibration viscometer, and it was 1400 mPa · sec. The results are shown in Table 1.

  Next, using the raw material solution S obtained in this comparative example, the cellulose fiber was spun by the spinning device 1 shown in FIG. Although spinning was possible, when the winding speed was higher than 32.4 m / min, the fiber was frequently cut and the spinnability was poor. The results are shown in Table 1.

[Comparative Example 6]
In this comparative example, a raw material solution S was prepared in exactly the same manner as in Example 2, except that an ionic liquid composed of 1-butyl-3-methylimidazolium chloride was used as the ionic liquid.

  The absorbent cotton was heated in the ionic liquid for 4.0 hours in the same manner as in Example 2. Moreover, when the viscosity at 60 degreeC of the raw material solution S was measured using the vibration viscometer, it was 1500 mPa * second. The results are shown in Table 1.

  Next, using the raw material solution S obtained in this comparative example, the cellulose fiber was spun by the spinning device 1 shown in FIG. Although spinning was possible, when the winding speed was higher than 18.2 m / min, the fiber was frequently cut and the spinnability was poor. The results are shown in Table 1.

[Comparative Example 7]
In this comparative example, a raw material solution S was prepared in exactly the same manner as in Example 2 except that the ionic liquid was heated at 120 ° C. for 4.5 hours.

  It was 280 mPa * sec when the viscosity at 60 degrees C of the raw material solution S was measured using the vibration viscometer. The results are shown in Table 1.

  Next, using the raw material solution S obtained in this comparative example, an attempt was made to spin the cellulose fiber F with the spinning device 1 shown in FIG. 1, but the fiber was not formed well and spun because the degree of polymerization was too low. I couldn't. The results are shown in Table 1.

  In the table, AmimCl is 1-allyl-3-methylimidazolium chloride, EmimAc is 1-ethyl-3-methylimidazolium acetate, EmimCl is 1-ethyl-3-methylimidazolium chloride, and BmimCl is 1. -Represents butyl-3-methylimidazolium chloride.

  In the table, the maximum winding speed indicates the maximum speed at which the yarn can be wound without being cut for 10 minutes. When the yarn winding speed is 100 m / min or less, the practical utility is low. Therefore, as an evaluation of the spinnability, ◯ indicates that the fiber can be spun at a speed of 100 m / min or more, △ indicates that the fiber can be spun, but the maximum winding speed is less than 100 m / min, and x indicates that the fiber cannot be wound. Represents.

  From Table 1, dissolved pulp or absorbent cotton, which is a cellulose raw material containing 95% by mass or more of cellulose with respect to the total amount, having a crystallinity of 70% or more and an average polymerization degree measured by the TAPPI method of 1000 or more, and 1-allyl-3 -It is clear that the raw material solution S can be obtained in a short time and cellulose fibers can be obtained with good spinnability by the combination with an ionic liquid comprising methylimidazolium chloride. In addition, if an ionic liquid composed of 1-ethyl-3-methylimidazolium acetate is combined with a cellulose raw material having a relatively low degree of polymerization such as dissolved pulp, the raw material solution S can be obtained in a short time, and spinning. It is clear that cellulose fibers can be obtained with good properties.

  On the other hand, in the combination of cellulose raw materials other than the dissolving pulp or absorbent cotton and an ionic liquid composed of 1-allyl-3-methylimidazolium chloride (Comparative Examples 1 and 2), the fiber is frequently cut and the spinning itself Obviously you can't.

  In addition, the combination of the dissolving pulp or absorbent cotton and the ionic liquid composed of other imidazolium compounds other than 1-allyl-3-methylimidazolium chloride (Comparative Examples 3 to 6) clearly shows that the spinnability is not good. It is.

  Furthermore, in the combination (the comparative example 7) of the said melt | dissolution pulp or cotton wool, and the ionic liquid which consists of 1-allyl-3-methylimidazolium chloride, it is made to heat-process excessively and the cellulose polymerization degree of a raw material solution falls too much. Therefore, it is clear that the spinnability deteriorates.

  When 1-ethyl-3-methylimidazolium chloride is used as the ionic liquid, when the raw material is heat-treated under the same conditions as 1-allyl-3-methylimidazolium chloride, the dissolved state of the raw material solution becomes uneven and highly viscous. When the winding speed is 32.4 to 38.5 m / min or more, although spinning is possible, the fiber is cut, resulting in poor spinnability, and practical cellulose fibers cannot be obtained.

  Even when 1-butyl-3-methylimidazolium chloride is used as the ionic liquid, if the raw material is heat-treated under the same conditions as 1-allyl-3-methylimidazolium chloride, the dissolved state of the raw material solution is uneven and high viscosity Thus, although spinning is possible, when the winding speed is 18.2 to 23.5 m / min or more, the fiber is cut, and thus the spinning property is poor, and it is impossible to obtain a practical cellulose fiber.

  Moreover, when the fiber diameter of the spun fiber was measured with a scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.), the fiber diameters of the fibers obtained in Examples 1, 2, and 3 were 25.2 μm and 28. 4 μm and 25.6 μm. On the other hand, the fiber diameters of the fibers obtained in Comparative Examples 3 to 6 that could be spun were 39.2 μm, 46.5 μm, 41.1 μm, and 51.2 μm, respectively. In Comparative Examples 3 to 6, spinning was possible, but the diameter was larger than the fiber diameter of the fibers obtained in the examples. As the fiber diameter becomes larger, when these are twisted together to form a yarn, the flexibility is lacking, so the fiber is not practical.

  In order to spin cellulose fibers, it is necessary that not only the cellulose raw material is dissolved in the ionic liquid but also the average degree of polymerization is 300 or more. This is because when the average degree of polymerization is 300 or less, the fiber becomes brittle and the fiber is frequently cut.

  As is apparent from the results in Table 1, when 1-allyl-3-methylimidazolium chloride is used, the solution viscosity after dissolution of the cellulose raw material is lower and spinnability is better than when other ionic liquids are used. . Therefore, if 1-allyl-3-methylimidazolium chloride is used, there is a possibility that a cellulose raw material solution that can be spun can be prepared even with a high molecular weight cellulose raw material.

  Therefore, the dissolution of the cellulose raw material was analyzed using a raw material solution whose average degree of polymerization was previously known and changing the temperature conditions. As a control, 1-ethyl-3-methylimidazolium acetate was used to compare dissolution and decomposition of cellulose raw materials.

  Table 2 shows the analysis results when cellulose having an average degree of polymerization of 9000 is used as a raw material, and Table 3 shows the case where cellulose having an average degree of polymerization of 1500 is used as a raw material.

  Using Indian cotton as the raw material with an average degree of polymerization of 9000 and absorbent cotton as the raw material with an average degree of polymerization of 1500, a raw material solution having a cellulose concentration of 5% (ionic liquid 9.5 g, cellulose 0.5 g) was prepared and subjected to dissolution analysis. . The average degree of polymerization was measured by the TAPPI method as described above.

  In addition, what underlined the average degree of polymerization shows that the cellulose raw material is melt | dissolving by visual observation.

  The average polymerization degree of cellulose contained in the cellulose raw material refers to a substance obtained by dissolving solid cellulose and measuring the polymerization degree by the TAPPI method, and means the average polymerization degree of the raw material itself. For example, in Table 2, cellulose having an average polymerization degree of 9000 is used as a raw material. The average degree of polymerization after treatment with the ionic liquid refers to the average degree of polymerization after dissolution in the ionic liquid and cleavage of the raw material cellulose. Spinning is possible when the average degree of polymerization after dissolution in the ionic liquid is in the range of 300-4300.

  As is clear from Tables 2 and 3, when 1-allyl-3-methylimidazolium chloride was used to dissolve the cellulose raw material, the average degree of polymerization of the raw material suddenly decreased with time. Go. In contrast, when 1-ethyl-3-methylimidazolium acetate is used, no significant decrease in molecular weight is observed.

  From this, 1-ethyl-3-methylimidazolium acetate probably breaks hydrogen bonds between cellulose molecular chains, whereas 1-allyl-3-methylimidazolium chloride breaks down hydrogen bonds with cellulose. It is considered that the covalent bond between glucoses constituting the nuclease is cleaved.

  As shown in Table 2, when EmimAc was used, dissolution was confirmed by visual observation after treatment at 120 ° C. for 12 hours, and the average degree of polymerization at this time was 7200. However, this raw material solution had high viscosity and poor spinnability. On the other hand, the raw material solution treated with AmimCl at 120 ° C. for 6 hours had an average degree of polymerization of 4100 and good spinnability. From other experiments, it has been confirmed that if the average degree of polymerization is 4300 or more, the viscosity is high and the spinnability is poor, but if the average degree of polymerization is about 4300, it can be spun well.

  Therefore, in order to spin cellulose fibers, it is necessary not only to dissolve the cellulose raw material in the ionic liquid but also to lower the molecular weight to an average degree of polymerization of 300 to 4300. As described above, when the average degree of polymerization is 300 or less, the fiber becomes brittle, and the fiber is frequently cut. When the average degree of polymerization is 4300 or more, the raw material solution has high viscosity and the spinnability is poor.

  As shown in Table 2, when 1-allyl-3-methylimidazolium chloride is used, an average degree of polymerization of about 300 to 4300 that can be spun in a relatively short time even when a polymer cellulose raw material is used as the raw material. The cellulose molecular chain is broken up to. For example, by treating at 120 ° C. for 6 hours, the average degree of polymerization becomes 4100, and a spinnable raw material solution can be obtained.

  On the other hand, when 1-ethyl-3-methylimidazolium acetate is used, even if it is heated at 120 ° C. for 12 hours, the average degree of polymerization is 7200, and the viscosity of the raw material solution is high, so that fibers are obtained with good spinnability. It is difficult. Thus, when treated with 1-ethyl-3-methylimidazolium acetate, it is necessary to treat at a high temperature for a long time in order to cut the cellulose to an average degree of polymerization that can be spun.

  As shown in Table 3, when a low molecular weight cellulose raw material with a low average degree of polymerization is used, when 1-allyl-3-methylimidazolium chloride is used, it is treated at 60 ° C. for 6 hours. By doing so, cellulose can be dissolved without reducing the molecular weight.

  From the above analysis results, when 1-allyl-3-methylimidazolium chloride is used, cellulose can be spun by heating at about 70 ° C. or higher even when a high molecular weight cellulose raw material having an average polymerization degree of 4300 or higher is used. 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 degree of polymerization of less than 4300 is used, the cellulose raw material can be dissolved by heating at a low temperature of less than about 70 ° C. without reducing the molecular weight much.

  Furthermore, when the cellulose raw material is dissolved using 1-allyl-3-methylimidazolium chloride, it is also possible to suppress molecular weight reduction by heating and dissolving in a nitrogen atmosphere.

  Therefore, by using 1-allyl-3-methylimidazolium chloride, a raw material solution suitable for spinning can be easily prepared by adjusting the heating temperature, treatment time, and atmosphere according to the average degree of polymerization of the cellulose raw material. Can do.

  As described above, 1-allyl-3-methylimidazolium chloride has the property of reducing the molecular weight of cellulose molecules compared to other ionic liquids, and therefore, even if it is a polymer cellulose raw material, it can be spun. However, the molecular weight can be reduced to a possible molecular weight. In addition, the cellulose raw material can be dissolved in a short time at a relatively low temperature as compared with other ionic liquids, and a raw material solution having excellent spinnability can be obtained. Therefore, it has the effect that it is safe and has good workability, and the cost required for heating is comparable to other ionic liquids.

  DESCRIPTION OF SYMBOLS 1 ... Spinning apparatus, 2 ... Base, 5 ... Coagulating liquid tank, 6 ... Coagulating liquid, 7 ... Conduit, 8 ... Nozzle, 10 ... Drying process, S ... Raw material solution.

In order to achieve this object, the cellulose fiber production method of the present invention comprises a step of dissolving a cellulose raw material in an ionic liquid composed of an imidazolium compound to obtain a raw material solution, and the raw material solution is soluble in the imidazolium compound. And a step of coagulating the cellulose contained in the raw material solution by extruding into a coagulating liquid in which cellulose is insoluble, and the cellulose raw material contains 95% by mass of cellulose with respect to the total amount. A step of obtaining the raw material solution, wherein the crystallinity is 70% or more, the average degree of polymerization of the contained cellulose is 1000 or more, and the imidazolium compound is 1-allyl-3-methylimidazolium chloride The average polymerization degree of the cellulose raw material becomes 300 to 4300 at a dissolution temperature of 30 to 60 ° C. It is characterized by dissolving up to. Thereby, the raw material solution excellent in spinnability can be obtained. The average degree of polymerization of the cellulose raw material is an average degree of polymerization measured by the TAPPI method (viscosity method).

If the degree of polymerization after dissolution in an ionic liquid of cellulose raw material is less than 300, fiber formation may not be possible, and even if the fiber is spun, the strength of the cellulose fiber obtained is lowered. If the degree of polymerization after dissolution exceeds 4300, the viscosity of the raw material solution increases and spinnability is reduced. Further, in the step of obtaining a raw material solution, to dissolve until the average degree of polymerization of the cellulose to 300-4300 is the average degree of polymerization of the cellulose raw material, by adjusting the dissolve time or dissolution temperature, optionally the material cellulose dissolved until the average degree of polymerization. As the ionic liquid consisting of imidazolium compounds, in the step of obtaining a raw material solution, in order to stably the cellulose material to the desired average degree of polymerization, 1 - allyl-3-Ru have use methylimidazolium chloride.
Moreover, it is preferable that the viscosity in 60 degreeC measured using the vibration type viscometer of the said raw material solution is 700-750 mPa * second.

Here, when melt | dissolving a cellulose raw material in an ionic liquid, it melt | dissolves until the average polymerization degree of the cellulose containing the cellulose raw material of average polymerization degree 1000 or more will be set to 300-4300. Therefore, dissolution temperature to 30 ℃ ~ 60 ℃. The dissolution time is 0.5 hours to 20 hours .

The temperature of the coagulation liquid 6 is maintained at a temperature in the range of 0 ° C. to 100 ° C. in the case of water, and in the range of −40 to 100 ° C. in the case of lower alcohol. When the coagulating liquid 6 is water, it freezes when its temperature is less than 0 ° C., and vaporizes when the temperature exceeds 100 ° C., and in any case, cellulose cannot be made into fibers. Further, when the coagulation liquid 6 is a lower alcohol, if the temperature is lower than −40 ° C., the fluidity of the ionic liquid is lowered, and cellulose cannot be fibrillated. Dissolves quickly in the coagulation liquid 6 and the coagulation of cellulose proceeds prematurely, making it difficult to fiberize cellulose. In order to improve the spinnability, when the coagulation liquid 6 is water, it is kept at a temperature of 0 ° C. to 70 ° C., and when it is a lower alcohol, it is kept above the freezing point and at a temperature lower than the boiling point by 20 ° C. or more. It is preferable.

In the table, AmimCl represents 1-allyl-3-methylimidazolium chloride , E mimCl represents 1-ethyl-3-methylimidazolium chloride, and BmimCl represents 1-butyl-3-methylimidazolium chloride.

From Table 1, dissolved pulp or absorbent cotton, which is a cellulose raw material containing 95% by mass or more of cellulose with respect to the total amount, having a crystallinity of 70% or more and an average polymerization degree measured by the TAPPI method of 1000 or more, and 1-allyl-3 -It is clear that the raw material solution S can be obtained in a short time and cellulose fibers can be obtained with good spinnability by the combination with an ionic liquid comprising methylimidazolium chloride .

Furthermore, said dissolving pulp or cotton wool, in combination with the ionic liquid consisting of 1-allyl-3-methylimidazolium chloride (Comparative Example 7), excessive heat treatment result, reduced cellulose polymerization degree of the raw material solution over Gill Therefore, it is clear that the spinnability deteriorates.

Even when 1-butyl-3-methylimidazolium chloride is used as the ionic liquid, if the raw material is heat-treated under the same conditions as 1-allyl-3-methylimidazolium chloride, the dissolved state of the raw material solution becomes uneven and highly viscous. Although spinning is possible, if the winding speed is 18.2 to 23.5 m / min or more, the fiber is cut, which means that the spinning property is poor, and it is impossible to obtain practical cellulose fibers.

Also, spun fibers having a fiber diameter of a scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.) was measured by the fiber diameter of the fiber obtained in Example 1, 2 each 25.2μm, 28.4μ m It was. On the other hand, the fiber diameters of the fibers obtained in Comparative Examples 3 to 6 that could be spun were 39.2 μm, 46.5 μm, 41.1 μm, and 51.2 μm, respectively. In Comparative Examples 3 to 6, spinning was possible, but the diameter was larger than the fiber diameter of the fibers obtained in the examples. As the fiber diameter becomes larger, when these are twisted together to form a yarn, the flexibility is lacking, so the fiber is not practical.

Claims (5)

Dissolving a cellulose raw material in an ionic liquid composed of an imidazolium compound to obtain a raw material solution;
A step of extruding the raw material solution into a coagulating liquid in which the imidazolium compound is soluble and insoluble in cellulose, and coagulating the cellulose contained in the raw material solution.
The cellulose raw material contains 95% by mass or more of cellulose with respect to the total amount, the crystallinity is 70% or more, and the average polymerization degree of the contained cellulose is 1000 or more,
In the step of obtaining the raw material solution, the cellulose raw material is dissolved until the average degree of polymerization becomes 300 to 4300. 2. The method for producing cellulose fibers according to claim 1, wherein the imidazolium compound is 1-allyl-3-methylimidazolium chloride.   The method for producing cellulose fibers according to claim 1 or 2, wherein the cellulose raw material is dissolved pulp or absorbent cotton.   The manufacturing method of the cellulose fiber of any one of Claims 1-3 WHEREIN: The said coagulation | solidification liquid is the water of the temperature of the range of 0-100 degreeC, The manufacturing method of the cellulose fiber characterized by the above-mentioned. The method for producing cellulose fibers according to any one of claims 1 to 3, wherein the coagulation liquid is a lower alcohol having a temperature in the range of -40 to 100 ° C.