TWI634137B - High-strength and high-elastic cellulose long fiber, method for spinning the same, and fiber-reinforced composite material - Google Patents

Abstract

An object of the present invention is to provide a regenerated cellulose long fiber having high strength and high elasticity as a subject.

The solution of the present invention is to dissolve a cellulose raw material in an ionic liquid, and to obtain cellulose having an average polymerization degree of 500 μm or less and an average fiber diameter of 30 μm or less by the cellulose long fibers obtained by the spinning. Long fibers provide a high strength and high elasticity fiber.

Description

High-strength and high-elastic cellulose long fiber, method for spinning the same, and fiber-reinforced composite material

The present invention relates to a regenerated cellulose fiber which is obtained by dissolving a cellulose raw material in an ionic liquid, spinning and re-precipitating it in a solvent, and having high spinning strength, high strength and high elasticity, And its manufacturing method.

In order to improve the strength and rigidity of plastics, fiber composite materials of high strength and high elastic fibers such as glass fibers are used in various fields such as automobile parts, sporting goods, building materials, and groceries.

The glass fiber reinforced composite material that has been used as a lightweight high-strength material exhibits excellent properties in use. However, when glass fiber is used as a reinforced fiber, the load on the environment is large due to generation of residue at the time of disposal.

Moreover, in order to improve insulation and rigidity in a printed wiring board, glass fiber is used as a base material. However, when such a glass fiber is used, there is a problem that the load on the environment is large due to the generation of residue at the time of disposal.

Therefore, as a reinforcing fiber or printing compound for fiber reinforced composite materials The base material of the wire plate is used to study cellulose having excellent properties such as high mechanical properties, dimensional stability, low thermal expansion, electrical insulation, and low specific gravity. Since cellulose is biodegradable from plants, it does not generate residue when it is discarded, and the environmental load during production and disposal is small (for example, Patent Document 1).

In the past, research has also been conducted on fiber-reinforced composite materials using cellulose-based natural fibers such as cotton, hemp, kenaf, and bamboo as reinforcing fibers. However, there are many variations in strength, and short fibers are a problem that cannot be used for a wide range of applications. Therefore, the cellulose fiber having high cellulose purity or cellulose crystallinity and stable quality is desired, and the regenerated cellulose fiber of the long fiber is used for the fiber reinforced composite material or the electric material.

Regenerated cellulose fibers such as rayon fibers, copper ammonia fibers, and Lyocell fibers are known as regenerated cellulose fibers. However, any of the fibers is a highly toxic solvent or a solvent having a high risk such as an explosion, and the production process is accompanied by a risk, so that a method for producing a cellulose fiber having high safety is sought.

For this reason, a method of producing a regenerated cellulose fiber by using a ionic liquid composed of an imidazolium compound as a solvent and dissolving the cellulose raw material in the ionic liquid has been developed (see, for example, Patent Documents 2 to 4).

However, the current situation, as disclosed in the literature, is being reviewed for the dissolution of the cellulose raw material in the ionic liquid, but the industrial stable spinning of the regenerated cellulose long fiber has hardly been reviewed.

For example, in Patent Document 2, a nonwoven fabric is produced from cellulose dissolved in an ionic liquid, but no long fiber is obtained. Further, in Patent Documents 3 and 4, it is described that the cellulose raw material is dissolved in an ionic liquid and the fiber is spun, but the industrially stable spinning is not performed. Discussion. If the regenerated cellulose long fiber can be stably obtained, it can be easily used for secondary processing such as cloth or cloth, sheet, or film, or cut into a length such as a chopped strand, and used as an electric material or Fiber reinforced composites can be extended for a wide range of applications. Therefore, it is necessary to use an ionic liquid to stabilize and industrially spin regenerated cellulose long fibers. The present inventors have therefore established a technique for industrially and stably producing a cellulose raw material dissolved in an ionic liquid, and have been disclosed (Patent Document 5).

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-236321

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-248466

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-203467

[Patent Document 4] Japanese Laid-Open Patent Publication No. 2012-21048

[Patent Document 5] International Publication No. 2012/108390

[Non-patent literature]

[Non-Patent Document 1] Wada, M., Nishiyama, Y., Cellulose Commun. Vol.18, No.2, P87-P90, (2011)

The present inventors have established a technique for dissolving a cellulose raw material in an ionic liquid to produce a good spinning property, but for the spun regenerated cellulose long fiber, the strength and elasticity for use as a composite material or an electric material. The rate has not been discussed so far.

In the present invention, a regenerated cellulose long fiber having good productivity, high strength, and high elasticity is obtained.

The present invention relates to a high-strength and high-elastic cellulose long fiber which is a regenerated cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid, and is characterized in that the average degree of polymerization is 500 or more and 3,000 or less. The average fiber diameter is 30 μm or less.

In the present invention, the high-strength and high-elastic cellulose long fiber means a tensile strength of at least 0.55 GPa or more and a tensile modulus of 35 GPa or more.

The inventors of the present invention have disclosed a regenerated cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid, and spinning it as a fine fiber having an average fiber diameter of 30 μm or less, thereby having a tensile strength of 0.55 GPa. The above-mentioned high-strength and high-elastic cellulose long fibers having a tensile modulus of 35 GPa or more.

Reports relating to the fiber diameter of the regenerated cellulose fibers and the tensile strength and tensile modulus are unprecedented, and were first discovered by the inventors. Further, it is a highly advanced technique to obtain a slender fiber by dissolving a cellulose raw material in a cellulose solution of an ionic liquid, but by controlling a spinning condition such as a nozzle diameter, a spinning speed, or an extension, an average fiber diameter of 30 μm or less can be obtained. fiber. Further, the present inventors have found that if the average degree of polymerization of the ionic liquid is 500 or more and 3,000 or less, the long fiber which can be produced with good spinning properties can be spun high strength and high elasticity by adjusting the fiber diameter. fiber Long fiber.

Further, the high-strength and high-elasticity cellulose long fiber of the present invention is characterized in that the degree of intramolecular hydrogen bonding is 42% or more and 60% or less.

The degree of intramolecular hydrogen bonding shows the binding force of adjacent glucose to each other in the cellulose molecule, and it is considered that the higher the value, the more compact the structure. When the degree of intramolecular hydrogen bonding is 42% or more and 60% or less, a high-strength and high-elastic cellulose long fiber having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more can be obtained.

Further, the high-strength and high-elastic cellulose long fiber of the present invention is characterized in that the degree of birefringence is 68 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less.

The degree of birefringence is considered to be related to the molecular orientation of the monolithic structure composed of the crystal structure and the amorphous structure forming the fiber. When the degree of birefringence is 68 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less, a high-strength and high-elastic cellulose long fiber having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more can be obtained.

Further, the high-strength and high-elastic cellulose long fiber of the present invention is characterized in that the degree of intramolecular hydrogen bonding is 45% or more and 60% or less.

When the degree of hydrogen bonding in the molecule is 45% or more and 60% or less, a high-strength and high-elastic cellulose long fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more can be obtained. When the fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more is used as the reinforcing fiber or the substrate, it can exhibit properties equal to or higher than those of the glass fiber.

Further, the high-strength and high-elastic cellulose long fiber of the present invention is characterized in that the degree of birefringence is 70 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less.

When the degree of birefringence is 70 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less, a high-strength and high-elastic cellulose long fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more can be obtained. When the tensile strength is 0.80 GPa or more and the tensile modulus is 45 GPa or more, the fiber can exhibit properties equal to or higher than those of the glass fiber when used as a reinforcing fiber or a substrate.

Furthermore, the method of spinning a high-strength and high-elastic cellulose long fiber of the present invention is characterized in that the cellulose raw material is dissolved in an ionic liquid so that the average polymerization degree is 500 or more and 3,000 or less, and the average fiber diameter is Spinning was carried out in a manner of 30 μm or less.

By dissolving the cellulose raw material in an ionic liquid so that the average degree of polymerization is 500 or more and 3,000 or less, the fiber having an average fiber diameter of 30 μm or less can be industrially stably spun, and a tensile modulus of 35 GPa or more can be obtained. High strength and high elastic cellulose long fibers.

Further, the fiber-reinforced composite material of the present invention is characterized in that it is obtained by mixing high-strength and high-elastic cellulose long fibers with a resin.

By mixing the high-strength and high-elastic cellulose long fibers of the present invention, it is possible to obtain a fiber-reinforced composite material having a strength equal to or higher than that of a composite material in which glass fibers are used as reinforcing fibers.

Hereinafter, the present invention will be described with reference to the embodiments. The term "high-strength and high-elasticity cellulose long fibers" as used in the present invention means a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more. In addition, in the present specification, the long fiber refers to a fiber of 5 m or more, but is spun for good productivity. It is desirable to continuously perform spinning at 10,000 m or more without cutting.

Moreover, the high-strength and high-elasticity cellulose long fiber of the present invention is characterized in that the average degree of polymerization is 500 or more and 3,000 or less, and the average fiber diameter is 30 μm or less. The present inventors have found that there is a correlation between the average fiber diameter and the strength of the fiber, and when the average fiber diameter is 30 μm or less, the tensile strength is 0.55 GPa or more, and the tensile modulus is 35 GPa or more. When the tensile modulus is 35 GPa or more, since it has almost the same elastic modulus as that of the glass fiber, it has a function as a substitute for the glass fiber.

Further, the average fiber diameter is preferably 22 μm or less, the tensile strength is 0.75 GPa or more, the tensile modulus is 40 GPa or more, more preferably the average fiber diameter is 20 μm or less, and the tensile strength is 0.80 GPa or more, and the tensile modulus is 3. 45 GPa or more, and more preferably, the average fiber diameter is 12 μm or less, the tensile strength is 0.95 GPa or more, the tensile modulus is 50 GPa or more, the average fiber diameter is 6 μm or less, and the tensile strength is 1.10 GPa or more. The modulus of elasticity is 55 GPa or more, the optimum fiber diameter is 4 μm or less, the tensile strength is 1.50 GPa or more, and the tensile modulus is 60 GPa or more. Here, the lower limit of the average fiber diameter of the high-strength and high-elasticity cellulose long fibers of the present invention is 1 μm from the viewpoint of the difficulty in production.

The high-strength and high-elasticity cellulose long fiber of the present invention has an average polymerization degree of 500 or more and 3,000 or less and an average fiber diameter of 30 μm or less. When the average degree of polymerization exceeds 3,000, since it is difficult to dissolve in the ionic liquid, it is difficult to stably spin the fine fibers due to the influence of the undissolved matter or the viscosity of the cellulose solution becoming too high. Moreover, when the average degree of polymerization is 500 or less, It is impossible to spin a fiber having a high tensile strength and a high tensile modulus.

Further, the high-strength and high-elasticity cellulose long fiber of the present invention has an average polymerization degree of 500 or more and 2,000 or less, and is preferably from the viewpoint of spinnability, and the average polymerization degree is 600 or more and 1800 or less, but It is more preferable to obtain a fiber having excellent spinnability, tensile strength, and tensile modulus. In order to obtain a finer filament, the average degree of polymerization is easy to spin, but in order to obtain high-strength and high-elastic cellulose long fibers, it is necessary to have a certain degree of average degree of polymerization. When it is the range of the above average degree of polymerization, a cellulose long fiber having good spinnability, high strength, and high elasticity can be obtained.

When the intramolecular hydrogen bonding degree of the high-strength and high-elasticity cellulose long fiber of the present invention is 42% or more and 60% or less, the tensile strength is 0.55 GPa or more, and the tensile modulus is 35 GPa or more. When the intramolecular hydrogen bonding degree is 44% or more and 60% or less, the tensile strength is 0.70 GPa or more, the tensile elastic modulus is 40 GPa or more, and more preferably, the intramolecular hydrogen bonding degree is 45% or more and 60% or less. The tensile strength was 0.80 GPa or more, and the tensile modulus was 45 GPa or more.

When the birefringence is 68 ⊿×10 ^-3 or more and 90 ⊿×10 ^-3 or less, the tensile strength is 0.55 GPa or more and the tensile modulus is 35 GPa or more. Further, the birefringence is preferably 69 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less, the tensile strength is 0.75 GPa or more, the tensile modulus is 40 GPa or more, and more preferably the birefringence is 70. ⊿ × 10 ^-3 or more and less 90⊿ × 10 ^-3, a tensile strength above 0.80GPa become, the tensile elastic modulus becomes 45GPa or more, still more preferably a degree of birefringence based 71⊿ × 10 ^-3 or more and 90⊿ × 10 ^-3 or less, the tensile strength is 1.00 GPa or more, the tensile modulus is 50 GPa or more, and the particularly preferred birefringence is 74 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less, and the tensile strength is 1.05 GPa. The tensile modulus is preferably 53 GPa or more, and the optimum birefringence is 80 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less, the tensile strength is 1.50 GPa or more, and the tensile modulus is 60 GPa or more.

Here, the high-strength and high-elasticity cellulose long fiber of the present invention has an average degree of polymerization of 700 or more and 2000 or less, an average fiber diameter of 6 μm or less, and an intramolecular hydrogen bonding degree of 49% or more and 60% or less. The degree of birefringence is 74 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less, the tensile strength is 1.10 GPa or more, the tensile modulus is 55 GPa or more, and the optimum degree of polymerization is 700 or more and 2000 or less. The fiber diameter is 4 μm or less, the intramolecular hydrogen bonding degree is 50% or more and 60% or less, and the birefringence is 80 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less.

[Method for producing high-strength and high-elastic cellulose long fibers]

The high-strength and high-elasticity cellulose long fiber of the present invention is obtained by dissolving a cellulose raw material in an ionic liquid composed of an imidazolium compound to obtain a cellulose solution. Next, the cellulose solution is produced by extruding the imidazolium compound into a coagulating liquid in which cellulose is insoluble, and solidifying the cellulose contained in the cellulose solution.

As a raw material of cellulose, basically anything can be used, for example, natural cellulose raw materials such as wood pulp, cotton, cotton linters, hemp, bamboo, abaca, or recycled fibers of rayon or copper ammonia, lyocell, etc. can be used. And the paper or clothing made of these materials is reused as a cellulose raw material to make Can also be used. From the viewpoint of economy, it is preferably a natural cellulose raw material in which dissolving pulp, cotton linters or bamboo is preferable because of the high purity of cellulose or the average degree of polymerization of cellulose.

When the cellulose purity of the cellulose raw material is high, the fat content of the cellulose raw material or the inclusions such as lignin or hemicellulose is small, and the homogeneity of the cellulose solution or the spinnability and elongation at the time of spinning are not hindered. .

Further, in consideration of the physical properties of the obtained fiber, the average degree of polymerization of the cellulose is preferably at least 500, and is preferably from 3,000 or less in solubility.

Examples of the ionic liquid composed of an imidazolium compound include 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, and 1-ethyl-3-methyl. Imidazolium diethyl-phosphate, 1-butyl-3-methylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1-ethyl-3-methylimidazolium Acid ester, 1-allyl-3-methylimidazolium chloride, and the like. Preferred examples are 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium phosphate.

When such an ionic liquid is used, a cellulose having an average degree of polymerization of an average degree of polymerization of 800 or more can be easily dissolved.

The dissolution time or the dissolution temperature can be adjusted by the average degree of polymerization of the cellulose or the type of the ionic liquid, and the cellulose raw material can be dissolved until it becomes a homogeneous solution.

Although the heating means is arbitrary, it is sufficient to use a general heating means such as heating by an oven, heating by a water bath or an oil bath, heating by microwaves, or the like.

Moreover, when heating, in order to promote the dissolution of the cellulose raw material, Stirring is preferred. The stirring means is also arbitrary, and it can be used from a known stirring method represented by mechanical stirring of a stirring bar or a stirring blade, stirring by shaking of a container, stirring by ultrasonic irradiation, etc. by appropriate means, etc. by scale. .

Further, in the case of heating and dissolution, in order to suppress oxidation of cellulose. The decomposition is preferably carried out in an inert gas atmosphere such as nitrogen.

The cellulose solution obtained by dissolving the cellulose raw material in the ionic liquid may be used as it is in the subsequent step. However, if the undissolved or insoluble fraction remains in the solution, it may be used after filtering.

In addition, the obtained cellulose solution may be used after being stored for a specific period of time in a range in which properties such as moldability and physical properties of the molded article can be maintained. In particular, after dissolving, it can be stored for a long period of time while being stored at a temperature of room temperature or lower while paying attention to moisture absorption.

After the dissolved cellulose is extruded from the nozzle, it is spun by immersing it in a coagulating liquid. As the coagulation liquid, water having a temperature in the range of 0 ° C or more and 100 ° C or less, or a lower alcohol having a temperature in the range of -40 ° C or more and 100 ° C or less, a polar solvent, a nonpolar solvent, or the like can be used. When considering economics and work environment, it is better to use water. Further, the lower alcohol refers to an alcohol having 1 or more and 5 or less carbon atoms.

The spun regenerated cellulose long fiber is washed with water, but the residual amount of the ionic liquid after washing is converted into the amount of ionic liquid from the amount of nitrogen detected by elemental analysis of the regenerated cellulose long fiber. It becomes 10000 ppm or less.

In order to manufacture long fiber of regenerated cellulose with different fiber diameters, When the flow rate is discharged, the cellulose solution is extruded from nozzles having different diameters, and spinning can be performed while controlling the take-up speed or the extension condition. For example, a cellulose fiber having a fiber diameter of 20 μm is a nozzle having a diameter of 0.15 mm, and the extrusion flow rate is fixed at a range of 0.01 to 1 mL/min, and the winding speed and the elongation ratio are gradually increased while the fiber diameter is 20 μm. It is obtained by spinning.

Further, when the fiber-reinforced composite material is produced, at least one resin selected from the group consisting of a thermoplastic resin and a thermosetting resin and a high-strength and high-elastic cellulose long fiber are mixed. As the thermoplastic resin in the fiber-reinforced composite material, polyamine (nylon), polyacetal, polycarbonate, polyvinyl chloride, ABS, polyfluorene, polyethylene, polypropylene, polystyrene, (methyl) can be exemplified. The acrylic resin, the fluororesin, and the melamine resin, and examples of the thermosetting resin include an unsaturated polyester resin, an epoxy resin, a melamine resin, and a phenol resin. When the fiber-reinforced composite material contains a thermosetting resin, the fiber-reinforced composite material includes a fiber-reinforced composite material that completely cures the thermosetting resin, and a pre-hardened state in which the thermosetting resin is semi-hardened. Dipper. Further, the fiber-reinforced composite material may contain additives such as a low shrinkage agent, a flame retardant, a flame retardant, a plasticizer, an antioxidant, an ultraviolet absorber, a colorant, a pigment, a filler, and the like, if necessary.

[Measurement of physical properties of regenerated cellulose long fibers]

The physical properties of the cellulose fibers obtained by the above method were measured by the following methods, and they were concentrated in Table 1.

(average fiber diameter)

The average fiber diameter was measured by a scanning electron microscope (manufactured by Hitachi, Ltd., SN-3400N). The fiber diameter of 10 points was measured from the regenerated cellulose long fiber section (fiber length: 20 mm), and the average value was made into the average fiber diameter.

(tensile strength, tensile modulus, elongation)

Tensile strength, tensile modulus, and elongation were measured using a tensile tester (manufactured by Orientec, TENSILON RTC-1150A) under the conditions of test piece length: 50 mm, tensile test speed: 5 mm/min, and load component load: 2N. . The test piece was dried at 110 ° C for 1 hour, and after cooling to room temperature in a desiccator, it was evaluated.

(birefringence)

The measurement of the degree of birefringence was carried out by a compensating method using a polarizing microscope (manufactured by Olympus Co., Ltd., BH-2) using incident light of 546 nm, and was obtained by the following calculation formula. Further, in the present invention, the degree of birefringence is defined as a value measured by the present method.

⊿n={nλ+aλ(x-1605)}/d

n: number of stripes seen in the fiber profile, λ: wavelength of incident light (546 nm), d: thickness of the fiber (nm), aλ: fixed number determined by the light source and the compensator (0.97), x: read value

(average degree of polymerization)

The average degree of polymerization of cellulose is determined by the TAPPI T230 standard method (viscosity method), and is calculated by dividing the measured average molecular weight by the molecular weight of glucose which is a constituent unit of cellulose. Moreover, in the present invention, the average degree of polymerization is defined as the value calculated by the method.

(crystal orientation)

The measurement of the crystal orientation was carried out in accordance with JIS K0131. Specifically, the measurement was carried out by a transmission method using ROTA-Flex RTP-300 manufactured by Rigaku Corporation, an X-ray diffraction device. The regenerated cellulose long fibers set on the fiber sample stage were irradiated with X-rays for 30 minutes, and detected by an image plate detector, and analyzed by a device for reading the detected value (R-AXIS DS3C, manufactured by Rigaku Corporation). Seek. Further, in the present invention, the crystal orientation is defined as a value measured by the present method.

(degree of crystallization)

The measurement of the degree of crystallization was carried out by a reflection method using a Multi Flex manufactured by Rigaku Corporation, an X-ray diffraction device. The regenerated cellulose long fibers were placed on the sample stage, and X-rays were irradiated while rotating the sample stage at 120 rpm, and the measurement speed was 1°/min at a measurement range of 5° or more and 40° or less, and was detected using a scintillation counter. The degree of crystallization was calculated from the obtained spectral data using a peak separation method (area method) (Non-Patent Document 1). Further, in the present invention, the degree of crystallization is defined as a value measured by the method.

(Measurement of intramolecular hydrogen bonding)

The intramolecular hydrogen bonding degree was measured by a CPMAS method using a solid NMR measuring apparatus manufactured by Bruker Co., Ltd. and AVANCE 300. The observed nuclei were detected as ¹³ C (resonance frequency 75.4 MHz), MAS condition was 3 kHz, and contact time was 2 msec. Further, in the present invention, the degree of intramolecular hydrogen bonding is defined as a value measured by the present method.

In Examples 1 to 8, and Comparative Examples 1 and 2, the cellulose raw material was dissolved in an ionic liquid, and then extruded from a nozzle to carry out spinning. At this time, fibers having different diameters are obtained by changing the nozzle diameter, the winding speed, the stretching conditions, and the like, and the physical properties have been measured.

In Comparative Example 1, when the average degree of polymerization was 880, the average fiber diameter was as large as 41.0 μm, and Comparative Example 2 was a fiber obtained by measuring the average degree of polymerization of the spinning smaller than the range of the present invention. The result of physical properties. Comparative Examples 3 to 5 show that within the range of the fiber diameter of the present invention The result of measuring the physical properties of the regenerated cellulose long fibers. Comparative Example 3 shows copper ammonia, Comparative Example 4 shows rayon, and Comparative Example 5 shows lyocell.

As shown in Table 1, the regenerated cellulose long fibers obtained by spinning the cellulose raw material in an ionic liquid, the finer the average fiber diameter, the higher the tensile strength and the tensile modulus.

In particular, as shown in Example 1, the fine regenerated cellulose long fibers having an average fiber diameter of 3.1 μm have a tensile strength of 1.54 GPa, a tensile modulus of 62.5 GPa, and the same as those of the glass fibers produced by E glass. Physical properties.

Further, as shown in Comparative Examples 3 to 5, copper ammonia, rayon, and lyocell were analyzed for the existing regenerated cellulose long fibers, but the high strength and high elasticity of the present invention were not satisfied.

Comparative Examples 3 to 5 show evaluations of tensile strength, tensile modulus, and the like of copper ammonia, rayon, and lyocell having an average fiber diameter of about 10 μm. Other regenerated cellulose long fibers such as copper ammonia are considered to be the same as the long fibers obtained by dissolving the cellulose raw material of the present invention in an ionic liquid and spinning, and the higher the fiber diameter, the higher the strength and the higher the elasticity.

However, when the regenerated cellulose long fiber of the present invention having an average fiber diameter of 27.9 μm as shown in Example 8 was compared with the copper ammonia of Comparative Example 3, even when the fiber diameter was about 3 times, high tensile strength was obtained. Tensile modulus. According to this, it is considered that even if a fine fiber diameter of about 3 μm is obtained from other regenerated cellulose long fibers such as copper ammonia, it is not possible to obtain high strength and high elasticity as the regenerated cellulose long fibers of the present invention.

Regenerated cellulose long fibers such as rayon are considered to be due to spinning The conditions (extension, drying, etc.) produce crystallinity of different cellulose, or the degree of polymerization is lowered by treatment with a strong acid or a strong alkali, and it is difficult to obtain a regenerated cellulose long fiber having high physical properties.

In the regenerated cellulose long fiber having a low average degree of polymerization in which the ionic liquid of Comparative Example 2 is dissolved, the average degree of polymerization is used to obtain high strength because the regenerated cellulose long fiber is not obtained even if the fine fiber is spun. And one of the important factors of high elastic cellulose long fiber. Further, since the dissolution method of the ionic liquid is a relatively mild dissolution method, a regenerated cellulose long fiber which does not cause a decrease in the average degree of polymerization of cellulose can be obtained.

In addition, other regenerated cellulose long fibers such as copper ammonia have not been commercially available as a product having a minimum fiber diameter of 3 μm in the present embodiment, and it is considered that it is difficult to obtain fine fibers having good productivity.

Further, although the degree of hydrogen bonding in the molecule is an index indicating that hydrogen and oxygen are more closely bonded between the molecular chains of the cellulose, the crystallization and melting of the high-strength and high-elastic cellulose long fibers in which the ionic liquid is dissolved and crystallized are crystallized and crystallized. The degree of orientation, tensile strength, and tensile modulus of elasticity all show high correlation. Further, as shown in Comparative Examples 3 to 5, in the case of the cellulose fibers produced by other methods, there is no strong correlation between the degree of intramolecular hydrogen bonding and the tensile strength and the tensile modulus.

As described above, by dissolving the cellulose raw material in the ionic liquid, the average degree of polymerization is 500 or more and 3,000 or less, and the average fiber diameter is 30 μm or less, and the regenerated cellulose long fiber is spun, and the spun yarn can be made into glass. A high-strength, high-elastic cellulose long fiber, which is a substitute for fibers, is used as a base material for reinforcing fibers or printed wiring boards for fiber-reinforced composite materials.

Next, the regenerated cellulose long fibers of Example 4 are actually arranged in one direction, impregnated with an epoxy resin, placed in a mold, heated and hardened in a mold, and then released from the mold to produce a fiber-reinforced composite material. Physical property evaluation (developed product) such as bending elastic modulus, bending strength, and thermal expansion coefficient was performed. As a general regenerated cellulose long fiber as a control system, copper ammonia and E glass fiber having a comparatively high physical property are mixed with a resin to form a composite material. The results are shown in Table 2.

As shown in Table 2, when the fiber-reinforced composite material is used, the flexural modulus and coefficient of thermal expansion of the developed product are almost the same as those when E-glass fiber is used. The regenerated cellulose long fiber is used to obtain a bending elastic modulus equivalent to that of the glass fiber, and the regenerated cellulose long fiber of the present invention is the first one, and is used as a substrate or a fiber-reinforced composite material for a printed wiring board requiring high elastic modulus and low thermal expansion. The reinforced fiber is expected to be widely used.

As shown above, the high-strength and high-elastic cellulose long fiber of the present invention exhibits ultra-high tensile strength and pull compared with the conventional cellulose fiber. The modulus of elasticity is equal to or higher than the ratio of the elastic modulus of the tensile modulus to the specific gravity. Further, when the reinforcing fiber or the substrate is mixed with the resin, a fiber-reinforced composite material having excellent flexural modulus and a thermal expansion coefficient similar to that of E glass can be obtained.

Claims (6)

A high-strength and high-elasticity cellulose long fiber, which is a cellulose long fiber obtained by continuously spinning an ionic liquid solution of a cellulose raw material, which is characterized by an average degree of polymerization of 500 or more and 3,000 or less. The average fiber diameter is 30 μm or less, the degree of birefringence is 68 ⊿×10 ⁻³ or more and 90 ⊿×10 ⁻³ or less, the tensile strength is 0.55 GPa or more, and the tensile modulus is 35 GPa or more. The high-strength and high-elasticity cellulose long fiber of claim 1, wherein the intramolecular hydrogen bonding degree is 42% or more and 60% or less. The high-strength and high-elastic cellulose long fiber of claim 2, wherein the intramolecular hydrogen bonding degree is 45% or more and 60% or less. The high-strength and high-elasticity cellulose long fiber according to any one of claims 1 to 3, wherein the degree of birefringence is 70 ⊿ × 10 ^-3 or more and 90 ⊿ × 10 ^-3 or less. The invention relates to a method for spinning high-strength and high-elastic cellulose long fibers, which is a method for spinning high-strength and high-elastic cellulose long fibers, which is characterized in that an average liquidity of a cellulose raw material is 500 or more and 3000 in an ionic liquid. In the following manner, the ionic liquid solution of the cellulose raw material is continuously spun for 5 m or more so that the average fiber diameter is 30 μm or less and the birefringence is 68 ⊿×10 ⁻³ or more and 90 ⊿×10 ⁻³ or less. . A fiber reinforced composite material characterized by mixing as please The high strength and high elastic cellulose long fiber of any one of items 1 to 4 is obtained by a resin.