WO2015053226A1 - Long cellulose fibers having high strength and high elasticity - Google Patents

Long cellulose fibers having high strength and high elasticity Download PDF

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Publication number
WO2015053226A1
WO2015053226A1 PCT/JP2014/076713 JP2014076713W WO2015053226A1 WO 2015053226 A1 WO2015053226 A1 WO 2015053226A1 JP 2014076713 W JP2014076713 W JP 2014076713W WO 2015053226 A1 WO2015053226 A1 WO 2015053226A1
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cellulose
strength
fiber
less
gpa
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PCT/JP2014/076713
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French (fr)
Japanese (ja)
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昌範 和田
彰 吉村
あかね 武永
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日東紡績株式会社
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Priority to JP2015541569A priority Critical patent/JPWO2015053226A1/en
Publication of WO2015053226A1 publication Critical patent/WO2015053226A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C08J5/045—Reinforcing macromolecular compounds with loose or coherent fibrous material with vegetable or animal fibrous material
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
    • D01F2/02—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from solutions of cellulose in acids, bases or salts

Definitions

  • the present invention relates to a regenerated cellulose long fiber having good spinnability, high strength and high elasticity, and a method for producing the same, in a regenerated cellulose fiber obtained by dissolving a cellulose raw material in an ionic liquid and reprecipitating it in a solvent by spinning.
  • fiber composite materials blended with high-strength and high-elastic fibers such as glass fibers are used in various fields such as automobile parts, sporting goods, building materials, and miscellaneous goods.
  • the glass fiber reinforced composite material that has been used as a lightweight high-strength material exhibits excellent characteristics during use.
  • glass fiber is used as the reinforcing fiber, a residue is generated at the time of disposal, which causes a problem that the load on the environment is large.
  • glass fiber is used as a base material for the printed wiring board in order to improve insulation and rigidity.
  • a residue is generated at the time of disposal, which causes a problem that the load on the environment is large.
  • cellulose having excellent properties such as high mechanical properties, dimensional stability, low thermal expansion, electrical insulation, and low specific gravity as the base material for fiber reinforced composite materials and printed wiring boards. It is being considered. Since cellulose is derived from plants and has biodegradability, no residue is produced at the time of disposal, and the environmental load during production and disposal is small (for example, Patent Document 1).
  • regenerated cellulose fibers such as rayon fiber, cupra fiber, and lyocell fiber are known.
  • any fiber uses a highly toxic solvent or a solvent having a high risk of explosion, etc., there is a risk in the production process, a highly safe method for producing cellulose fibers is required. It was.
  • Patent Document 2 describes that a nonwoven fabric is produced from cellulose dissolved in an ionic liquid, but there is no description about obtaining cellulose long fibers.
  • Patent Documents 3 and 4 describe that a cellulose raw material is dissolved in an ionic liquid to spin a fiber, but industrially stable spinning is not considered. If regenerated cellulose long fibers can be stably obtained, secondary processing such as cloth, cloth, sheet, membrane material, and cutting into lengths according to applications such as chopped strands will be easy. It can be used in a wide range of applications as electrical materials and fiber reinforced composite materials. For this reason, it has been necessary to industrially spin regenerated cellulose filaments stably using an ionic liquid.
  • the inventors of the present invention have established and already disclosed a technique that can be industrially stably produced from a cellulose raw material dissolved in an ionic liquid (Patent Document 5).
  • An object of the present invention is to obtain a regenerated cellulose long fiber with high productivity and high strength and high elasticity.
  • the present invention is a regenerated cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid and spinning, wherein the average degree of polymerization is 500 or more and 3000 or less, and the average fiber diameter is 30 ⁇ m or less. It is a high strength and high elasticity cellulose continuous fiber.
  • the high-strength and high-elasticity cellulose continuous fiber means one having at least a tensile strength of 0.55 GPa or more and a tensile elastic modulus of 35 GPa or more.
  • the inventors of the present invention have obtained a regenerated cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid and spinning it, and spinning it as a thin fiber having an average fiber diameter of 30 ⁇ m or less, whereby a tensile strength of 0.55 GPa or more, It has been clarified that the tensile elastic modulus is high strength and high elasticity cellulose long fiber of 35 GPa or more.
  • the high-strength and high-elasticity cellulose long fiber of the present invention is characterized in that the intramolecular hydrogen bond degree is 42% or more and 60% or less.
  • the degree of intramolecular hydrogen bonding indicates the bonding strength between adjacent glucose molecules in the cellulose molecule, and it is considered that the higher the value, the denser the structure.
  • the intramolecular hydrogen bond degree is 42% or more and 60% or less, a high strength and highly elastic cellulose continuous fiber having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more can be realized.
  • the high-strength and high-elasticity cellulose continuous fiber of the present invention is characterized in that the birefringence is 68 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less.
  • the birefringence is said to correlate with the molecular orientation in the entire structure consisting of a crystalline structure and an amorphous structure forming the fiber.
  • the birefringence is 68 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less, it is possible to realize a high-strength and highly elastic cellulose filament having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more.
  • the high-strength and high-elasticity cellulose continuous fiber of the present invention is characterized by having an intramolecular hydrogen bond degree of 45% or more and 60% or less.
  • a high-strength and highly elastic cellulose continuous fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more can be obtained. If the fiber has a tensile strength of 0.80 GPa or more and a tensile elastic modulus of 45 GPa or more, it can exhibit characteristics equivalent to or higher than those of glass fibers when used as a reinforcing fiber or a substrate.
  • the high-strength and highly elastic cellulose continuous fiber of the present invention is characterized in that the birefringence is 70 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less.
  • a high-strength and highly elastic cellulose continuous fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more can be obtained. If the fiber has a tensile strength of 0.80 GPa or more and a tensile elastic modulus of 45 GPa or more, it can exhibit characteristics equivalent to or higher than those of glass fibers when used as a reinforcing fiber or a substrate.
  • the cellulose raw material is dissolved in an ionic liquid so that the average degree of polymerization is 500 or more and 3000 or less so that the average fiber diameter is 30 ⁇ m or less. It is characterized by being spun into
  • the fiber-reinforced composite material of the present invention is characterized by being obtained by mixing high-strength and high-elastic cellulose long fibers and a resin.
  • a fiber-reinforced composite material having a strength equal to or higher than that of a composite material in which glass fibers are mixed as reinforcing fibers can be obtained.
  • the high-strength and high-elasticity cellulose long fiber refers to those having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more.
  • the long fiber means a fiber of 5 m or longer.
  • the high-strength and highly elastic cellulose long fiber of the present invention is characterized by having an average degree of polymerization of 500 to 3000 and an average fiber diameter of 30 ⁇ m or less.
  • the present inventors have found that there is a correlation between the average fiber diameter and the fiber strength, and when the average fiber diameter is 30 ⁇ m or less, the tensile strength is 0.55 GPa or more and the tensile elastic modulus is 35 GPa or more. It revealed that. If the tensile elastic modulus is 35 GPa or more, it has a specific elastic modulus substantially equivalent to that of glass fiber, and thus functions sufficiently as a substitute for glass fiber.
  • the average fiber diameter is preferably 22 ⁇ m or less because the tensile strength is 0.75 GPa or more and the tensile modulus is 40 GPa or more.
  • the average fiber diameter is 20 ⁇ m or less, and the tensile strength is 0.80 GPa.
  • the tensile modulus is more preferably 45 GPa or more, and the average fiber diameter is preferably 12 ⁇ m or less, more preferably 0.95 GPa or more and the tensile modulus is 50 GPa or more.
  • 1 ⁇ m can be mentioned at present from the viewpoint of manufacturing difficulty.
  • the high-strength and highly elastic cellulose filaments of the present invention have an average degree of polymerization of 500 to 3000 and an average fiber diameter of 30 ⁇ m or less. If the average degree of polymerization exceeds 3000, it is difficult to dissolve in the ionic liquid, and therefore, the influence of undissolved substances and the viscosity of the cellulose solution become too high, so that it is difficult to stably spin fine fibers. Further, if the average degree of polymerization is 500 or less, fibers having high tensile strength and high tensile modulus cannot be spun.
  • the high-strength and highly elastic cellulose continuous fiber of the present invention preferably has an average degree of polymerization of 500 or more and 2000 or less from the viewpoint of spinnability, and an average degree of polymerization of 600 or more and 1800 or less is excellent spinnability. Further, it is more preferable because a fiber having tensile strength and tensile elastic modulus can be obtained. In order to obtain a finer yarn, the smaller the average degree of polymerization, the easier it is to spin. However, in order to obtain a high strength and highly elastic cellulose filament, a certain degree of average degree of polymerization is required. When the average degree of polymerization is within the above range, it is possible to obtain cellulose continuous fibers having good spinnability and high strength and high elasticity.
  • the high-strength and highly elastic cellulose long fiber of the present invention has a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more.
  • the tensile strength is preferably 0.70 GPa or more and the tensile modulus is 40 GPa or more, and the intramolecular hydrogen bond degree is 45% or more and 60% or less. More preferably, the tensile strength is 0.80 GPa or more and the tensile modulus is 45 GPa or more.
  • the high-strength and highly elastic cellulose continuous fiber of the present invention has a tensile strength of 0.55 GPa or more and a tensile elastic modulus of 35 GPa or more if the birefringence is 68 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less. Further, the birefringence is preferably 69 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less because the tensile strength is 0.75 GPa or more and the tensile elastic modulus is 40 GPa or more, and the birefringence is 70 ⁇ ⁇ 10.
  • the tensile strength is 0.80 GPa or more and the tensile modulus is 45 GPa or more, and the birefringence is 71 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3.
  • a tensile strength above 1.00GPa tensile more preferably from becoming a more 50GPa modulus, degree birefringence 74 ⁇ ⁇ 10 -3 or more 90 ⁇ ⁇ 10 -3 der less It tensile strength above 1.05GPa, particularly preferred since the tensile modulus is equal to or greater than 53GPa, that the degree of birefringence is less than 80 ⁇ ⁇ 10 -3 or more 90 ⁇ ⁇ 10 -3, the tensile strength is 1.
  • the most preferable is 50 GPa or more and the tensile elastic modulus is 60 GPa or more.
  • the high-strength and highly elastic cellulose long fiber of the present invention has an average degree of polymerization of 700 to 2000, an average fiber diameter of 6 ⁇ m or less, an intramolecular hydrogen bond degree of 49% to 60%, and a birefringence of 74 ⁇ .
  • the tensile strength is 1.10 GPa or more and the tensile elastic modulus is 55 GPa or more
  • the average degree of polymerization is 700 to 2000 and the average fiber diameter is ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less.
  • it is 4 ⁇ m or less
  • the degree of intramolecular hydrogen bonding is 50% or more and 60% or less
  • the birefringence is 80 ⁇ ⁇ 10 ⁇ 3 or more and 90 ⁇ ⁇ 10 ⁇ 3 or less.
  • the high-strength and highly elastic 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 extruded into a coagulating liquid in which the imidazolium compound is soluble and insoluble in cellulose, and the cellulose contained in the cellulose solution is coagulated to produce.
  • the cellulose raw material may be basically any material, for example, natural cellulose raw materials such as wood pulp, cotton, cotton linter, hemp, bamboo, abaca, regenerated cellulose fibers such as rayon, cupra, lyocell, and the like.
  • the resulting paper or clothing may be reused as a cellulose raw material.
  • natural cellulose raw materials are preferable, and among them, dissolving pulp, cotton linter and bamboo are preferable because of high cellulose purity and average cellulose polymerization degree.
  • the cellulose purity of the cellulose raw material is high, there are few impurities such as fats and oils, lignin and hemicellulose contained in the cellulose raw material, and the homogeneity of the cellulose solution, the spinnability during spinning, and the stretchability are not hindered.
  • the average degree of polymerization of cellulose is preferably at least 500 or more, and preferably 3000 or less in view of solubility, considering the physical properties of the obtained fiber.
  • Examples of the ionic liquid comprising an imidazolium compound include 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-butyl-3. -Methylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1-ethyl-3-methylimidazolium propionate, 1-allyl-3-methylimidazolium chloride and the like.
  • Preferred examples include 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium diethyl phosphate.
  • cellulose having a relatively large average degree of polymerization having an average degree of polymerization of 800 or more can be easily dissolved.
  • the dissolution time and dissolution temperature may be adjusted according to the average degree of polymerization of cellulose and the type of ionic liquid, and the cellulose raw material may be dissolved until it becomes a homogeneous solution.
  • the heating means is arbitrary, but general heating means such as heating with an oven, heating with a water bath or oil bath, heating with a microwave, etc. may be used.
  • Stirring means are also optional, and among the known stirring methods represented by mechanical stirring with a stirrer or stirring blade, stirring by shaking the container, stirring by ultrasonic irradiation, etc., an appropriate means according to the scale etc. Adopt it.
  • the cellulose solution obtained by dissolving the cellulose raw material in the ionic liquid may be used as it is in the subsequent step, but if undissolved or insoluble matter remains in the solution, after filtering these It may be used.
  • the obtained cellulose solution may be used immediately, but may be used after being stored for a predetermined time as long as various properties such as moldability and physical properties of the molded product can be maintained.
  • the product is stored at a temperature below room temperature while paying attention to moisture absorption, it can be stored for a long time.
  • the dissolved cellulose is extruded from a nozzle and then spun by immersing it in a coagulation liquid.
  • a coagulation liquid water having a temperature in the range of 0 ° C. or higher and 100 ° C. or lower, or a lower alcohol, a polar solvent, a nonpolar solvent, or the like having a temperature in the range of ⁇ 40 ° C. or higher and 100 ° C. or lower can be used. In view of economy and work environment, it is preferable to use water.
  • the lower alcohol means an alcohol having 1 to 5 carbon atoms.
  • the spun regenerated cellulose long fiber is washed with water, but the remaining amount of the ionic liquid after washing is 10000 ppm or less when converted from the nitrogen amount detected by elemental analysis of the regenerated cellulose long fiber to the ionic liquid amount.
  • the cellulose solution may be extruded from nozzles having different diameters while controlling the extrusion flow rate, and spinning may be performed while controlling the winding speed and stretching conditions. For example, for a cellulose fiber having a fiber diameter of 20 ⁇ m, a winding speed is gradually increased until the fiber diameter reaches 20 ⁇ m while fixing an extrusion flow rate in a range of 0.01 to 1 mL / min using a nozzle having a diameter of 0.15 mm. It can be obtained by spinning while increasing the draw ratio.
  • thermoplastic resin in the fiber reinforced composite material examples include polyamide (nylon), polyacetal, polycarbonate, polyvinyl chloride, ABS, polysulfone, polyethylene, polypropylene, polystyrene, (meth) acrylic resin, fluororesin, and melamine resin.
  • curable resin examples include unsaturated polyester resins, epoxy resins, melamine resins, and phenol resins.
  • the fiber reinforced composite material includes a thermosetting resin
  • the fiber reinforced composite material includes a prepreg in which the thermosetting resin is semi-cured in addition to the fiber reinforced composite material in which the thermosetting resin is completely cured. Is also included.
  • the fiber reinforced composite material contains additives such as a low shrinkage agent, a flame retardant, a flame retardant aid, a plasticizer, an antioxidant, an ultraviolet absorber, a colorant, a pigment, and a filler as necessary. It may be.
  • Average fiber diameter The average fiber diameter was measured with a scanning electron microscope (manufactured by Hitachi, Ltd., SN-3400N). Ten fiber diameters were measured from the regenerated cellulose long fiber slice (fiber length 20 mm), and the average value was defined as the average fiber diameter.
  • Test piece (Tensile strength, tensile modulus, elongation) Tensile strength, tensile modulus, and elongation were tested using a tensile tester (Orientec, TENSILON RTC-1150A) under the conditions of test piece length: 50 mm, tensile test speed: 5 mm / min, load cell load: 2N. . The test piece was subjected to an absolute drying treatment at 110 ° C. for 1 hour, and was evaluated after cooling to room temperature in a desiccator.
  • the birefringence was measured by a compensator method using an incident light of 546 nm with a polarizing microscope (Olympus, BH-2), and obtained from the following calculation formula.
  • the birefringence is defined as a value measured by this method.
  • ⁇ n ⁇ n ⁇ + a ⁇ (x ⁇ 1605) ⁇ / d n: number of fringes found in the fiber cross section, ⁇ : wavelength of incident light (546 nm), d: fiber thickness (nm), a ⁇ : constant determined by light source and compensator (0.97), x: reading value (average polymerization) Every time)
  • the average degree of polymerization of cellulose was calculated by measuring the average molecular weight by the TAPPI T230 standard method (viscosity method) and dividing the measured average molecular weight by the molecular weight of glucose, which is a constituent unit of cellulose. In the present invention, the average degree of polymerization is defined as a value calculated by this method.
  • Crystal orientation The crystal orientation was measured according to JIS K0131. Specifically, the measurement was performed by the transmission method using a ROTA-Flex RTP-300 manufactured by Rigaku Corporation which is an X-ray diffractometer. The regenerated cellulose long fiber set on the fiber sample stage was irradiated with X-rays for 30 minutes, detected with an imaging plate detector, and the detected value was determined by analyzing with a reading device (R-AXIS DS3C, manufactured by Rigaku Corporation). In the present invention, the degree of crystal orientation is defined as a value measured by this method.
  • Crystallinity The crystallinity was measured by a reflection method using a Multi Flex manufactured by Rigaku Corporation which is an X-ray diffractometer. While the regenerated cellulose long fiber was placed on the sample stage, the sample stage was rotated at 120 rpm, X-rays were irradiated, and detection was performed using a scintillation counter at a measurement speed of 1 ° / min in a measurement range of 5 ° to 40 °. Based on the obtained spectrum data, the crystallinity was calculated using a peak separation method (area method) (Non-patent Document 1). In the present invention, crystallinity is defined as a value measured by this method.
  • the intramolecular hydrogen bond degree was measured by CPMAS method using AVANCE300 manufactured by Bruker, which is a solid-state NMR measurement apparatus.
  • the detection nucleus was 13 C (resonance frequency 75.4 MHz), the MAS condition was 3 kHz, and the contact time was 2 milliseconds.
  • the degree of intramolecular hydrogen bonding is defined as a value measured by this method.
  • Examples 1 to 8 and Comparative Examples 1 and 2 were spun by dissolving a cellulose raw material in an ionic liquid and then extruding it from a nozzle. At that time, fibers having different diameters were obtained by changing the nozzle diameter, winding speed, stretching conditions, and the like, and the physical properties were measured.
  • Comparative Example 1 the average degree of polymerization is 880, which is within the range of the present invention, but the average fiber diameter is as large as 41.0 ⁇ m, and in Comparative Example 2, the average degree of polymerization is smaller than the range of the present invention. It is the result of having measured the physical property of the obtained fiber. Comparative Examples 3 to 5 show the results of measuring physical properties of conventional regenerated cellulose long fibers within the fiber diameter range of the present invention. Comparative Example 3 is a cupra, Comparative Example 4 is a rayon, and Comparative Example 5 is a lyocell.
  • the regenerated cellulose long fibers obtained by dissolving a cellulose raw material in an ionic liquid and spinning the finer the average fiber diameter the higher the tensile strength and the tensile elastic modulus.
  • a thin regenerated cellulose long fiber having an average fiber diameter of 3.1 ⁇ m has a tensile strength of 1.54 GPa, a tensile elastic modulus of 62.5 GPa, and physical properties equivalent to or higher than those of glass fiber produced from E glass. It has.
  • Comparative Examples 3 to 5 show evaluations such as the tensile strength and tensile modulus of cupra, rayon, and lyocell having an average fiber diameter of about 10 ⁇ m.
  • other regenerated cellulose long fibers such as cupra, it is also possible that, as with the long fibers obtained by dissolving the cellulose raw material of the present invention in an ionic liquid and spinning, the strength and elasticity become higher as the fiber diameter becomes smaller. .
  • the regenerated cellulose long fiber of the present invention having an average fiber diameter of 27.9 ⁇ m shown in Example 8 has a high tensile strength and tensile strength even though the fiber diameter is about 3 times that of the cupra of Comparative Example 3. Elastic modulus is obtained. Therefore, even if another regenerated cellulose long fiber having a thin fiber diameter of about 3 ⁇ m, such as cupra, is obtained, it is considered that the regenerated cellulose long fiber of the present invention has a higher strength and higher elasticity. Absent.
  • Regenerated cellulose filaments such as rayon are high because of differences in crystallinity of cellulose due to various spinning conditions (stretching, drying, etc.), and low polymerization degree due to treatment with strong acid or strong alkali. It is considered that regenerated cellulose long fibers having physical properties are difficult to obtain.
  • the degree of intramolecular hydrogen bonding is an index indicating that hydrogen and oxygen are bonded more closely between cellulose molecular chains.
  • cellulose long fibers dissolved and spun in an ionic liquid, It was also shown that the degree of crystallinity, the degree of crystal orientation, the tensile strength, and the tensile modulus are highly correlated.
  • Comparative Examples 3 to 5 in the case of cellulose fibers produced by other methods, there is not always a strong correlation between the degree of intramolecular hydrogen bonding, tensile strength, and tensile modulus.
  • the cellulose raw material is dissolved in an ionic liquid, and the regenerated cellulose long fibers are spun to an average degree of polymerization of 500 to 3000 and an average fiber diameter of 30 ⁇ m or less. It has become possible to spin high-strength and high-elasticity cellulose long fibers that can replace glass fibers as a base material for reinforcing fibers and printed wiring boards.
  • Example 4 the regenerated cellulose filaments of Example 4 were actually aligned in one direction, impregnated with epoxy resin, drawn into the mold, heated and cured in the mold, and then removed from the mold.
  • a fiber reinforced composite material was prepared and evaluated for physical properties such as flexural modulus, flexural strength, and thermal expansion coefficient (developed product).
  • cupra and E glass fibers which are general regenerated cellulose long fibers and have relatively high physical properties, were mixed with a resin at the same fiber content to prepare a composite material. The results are shown in Table 2.
  • the flexural modulus and thermal expansion coefficient of the developed product were almost the same as when E glass fiber was used.
  • the regenerated cellulose long fiber of the present invention was obtained for the first time using the regenerated cellulose long fiber, and the same bending elastic modulus as that of the glass fiber, and the substrate of the printed wiring board required to have high elastic modulus and low thermal expansion A wide range of applications are expected as reinforcing fibers for fiber-reinforced composite materials.
  • the high-strength and high-elasticity cellulose long fiber of the present invention exhibits a much higher tensile strength and tensile modulus than conventional cellulose fibers, and the specific modulus obtained by dividing the tensile modulus by specific gravity. Is equal to or better than glass fiber. Further, when mixed with resin as a reinforcing fiber or a base material, a fiber-reinforced composite material having an excellent bending elastic modulus and a thermal expansion coefficient similar to that when E glass is used can be obtained.

Abstract

The purpose of the present invention is to provide long regenerated-cellulose fibers with high strength and high elasticity. Long cellulose fibers obtained by dissolving a cellulose material in an ionic liquid and spinning the solution are prepared as long cellulose fibers having an average degree of polymerization of from 500 to 3000 inclusive and an average fiber diameter of 30 µm or less. Thus, it is possible to provide fibers with high strength and high elasticity.

Description

高強度かつ高弾性セルロース長繊維High strength and high elastic cellulose filament
　セルロース原料をイオン液体に溶解して、紡糸により溶媒中で再析出させることにより得られる再生セルロース繊維において、紡糸性が良く、高強度、かつ高弾性な再生セルロース長繊維、及びその製造方法に関する。 The present invention relates to a regenerated cellulose long fiber having good spinnability, high strength and high elasticity, and a method for producing the same, in a regenerated cellulose fiber obtained by dissolving a cellulose raw material in an ionic liquid and reprecipitating it in a solvent by spinning.
　プラスチックの強度と剛性を高めるために、ガラス繊維のような高強度かつ高弾性繊維を配合した繊維複合材料が自動車部品、スポーツ用品、建材、雑貨等、様々な分野で使用されている。 In order to increase the strength and rigidity of plastics, fiber composite materials blended with high-strength and high-elastic fibers such as glass fibers are used in various fields such as automobile parts, sporting goods, building materials, and miscellaneous goods.
　軽量高強度材料として用いられてきたガラス繊維強化複合材料は、使用中は優れた特性を発揮する。しかしながら、強化繊維としてガラス繊維を用いると、廃棄時に残渣が生じることから環境への負荷が大きいことが問題となっている。 The glass fiber reinforced composite material that has been used as a lightweight high-strength material exhibits excellent characteristics during use. However, when glass fiber is used as the reinforcing fiber, a residue is generated at the time of disposal, which causes a problem that the load on the environment is large.
　また、プリント配線板にも絶縁性、剛性を向上させるために、基材としてガラス繊維が用いられている。しかしながら、こちらもガラス繊維を用いると、廃棄時に残渣が生じることから環境への負荷が大きいことが問題となっている。 Also, glass fiber is used as a base material for the printed wiring board in order to improve insulation and rigidity. However, when glass fiber is also used here, a residue is generated at the time of disposal, which causes a problem that the load on the environment is large.
　そこで、繊維強化複合材料用の強化繊維やプリント配線板の基材として、高い機械的特性、寸法安定性、低熱膨張、電気絶縁性、低比重等の優れた特性を備えたセルロースを用いることが検討されている。セルロースは、植物由来であり生分解性を有することから、廃棄時に残渣が生じることがなく、生産、廃棄時の環境負荷が小さい（例えば、特許文献１）。 Therefore, it is necessary to use cellulose having excellent properties such as high mechanical properties, dimensional stability, low thermal expansion, electrical insulation, and low specific gravity as the base material for fiber reinforced composite materials and printed wiring boards. It is being considered. Since cellulose is derived from plants and has biodegradability, no residue is produced at the time of disposal, and the environmental load during production and disposal is small (for example, Patent Document 1).
　これまで、セルロース系天然繊維である綿や麻、ケナフ、竹などを強化繊維として利用した繊維強化複合材料の検討も行われている。しかし、強度のばらつきが多く、また、短繊維であるため幅広い用途に対応できないなどの問題が生じている。そのため、セルロース純度やセルロース結晶性が高く、品質が安定しており、なおかつ長繊維である再生セルロース繊維が繊維強化複合材料や電材用途に求められている。 So far, fiber-reinforced composite materials using cellulosic natural fibers such as cotton, hemp, kenaf and bamboo as reinforcing fibers have been studied. However, there are many problems such as variations in strength, and short fibers cannot be used in a wide range of applications. Therefore, the cellulose purity and cellulose crystallinity are high, the quality is stable, and regenerated cellulose fibers that are long fibers are required for fiber-reinforced composite materials and electrical materials.
　再生セルロース繊維としては、レーヨン繊維、キュプラ繊維、リヨセル繊維等の再生セルロース繊維が知られている。しかし、いずれの繊維も毒性の強い溶媒、あるいは、爆発等の危険性の高い溶媒を用いる等、製造工程に危険性を伴っていることから、安全性の高いセルロース繊維の製造方法が求められていた。 As regenerated cellulose fibers, regenerated cellulose fibers such as rayon fiber, cupra fiber, and lyocell fiber are known. However, since any fiber uses a highly toxic solvent or a solvent having a high risk of explosion, etc., there is a risk in the production process, a highly safe method for producing cellulose fibers is required. It was.
　そこで、溶媒としてイミダゾリウム化合物からなるイオン液体を用い、セルロース原料を該イオン液体に溶解して、再生セルロース繊維を製造する方法が開発されてきた（例えば、特許文献２～４参照）。 Therefore, a method for producing regenerated cellulose fibers by using an ionic liquid composed of an imidazolium compound as a solvent and dissolving a cellulose raw material in the ionic liquid has been developed (for example, see Patent Documents 2 to 4).
　しかしながら、現状では、これら文献に開示されているように、セルロース原料をイオン液体に溶解することについては検討されているものの、再生セルロース長繊維を工業的に安定して紡糸することについてはほとんど検討されていない。 However, at present, as disclosed in these documents, although it has been studied to dissolve cellulose raw materials in ionic liquids, almost no consideration is given to industrially spinning regenerated cellulose long fibers. It has not been.
　例えば、特許文献２では、イオン液体に溶解したセルロースから、不織布を製造することが記載されているが、セルロース長繊維を得ることについての記載はない。また、特許文献３、及び４ではイオン液体にセルロース原料を溶解して繊維を紡糸することが記載されてはいるものの、工業的に安定して紡糸することが検討されているわけではない。安定して再生セルロース長繊維を得ることができれば、クロスや布、シート、膜材のような二次加工や、チョップドストランドのような用途に応じた長さに切断して用いることが容易になり、電材用途や繊維強化複合材料として幅広い用途展開が可能となる。そのため、イオン液体を用いて安定して工業的に再生セルロース長繊維を紡糸することが必要とされていた。本発明者らは、そこでイオン液体に溶解したセルロース原料から工業的に安定して生産できる技術を確立し、すでに開示している（特許文献５）。 For example, Patent Document 2 describes that a nonwoven fabric is produced from cellulose dissolved in an ionic liquid, but there is no description about obtaining cellulose long fibers. Patent Documents 3 and 4 describe that a cellulose raw material is dissolved in an ionic liquid to spin a fiber, but industrially stable spinning is not considered. If regenerated cellulose long fibers can be stably obtained, secondary processing such as cloth, cloth, sheet, membrane material, and cutting into lengths according to applications such as chopped strands will be easy. It can be used in a wide range of applications as electrical materials and fiber reinforced composite materials. For this reason, it has been necessary to industrially spin regenerated cellulose filaments stably using an ionic liquid. The inventors of the present invention have established and already disclosed a technique that can be industrially stably produced from a cellulose raw material dissolved in an ionic liquid (Patent Document 5).
特開２０１１－２３６３２１号公報JP 2011-236321 A 特開２００８－２４８４６６号公報JP 2008-248466 A 特開２００９－２０３４６７号公報JP 2009-203467 A 特開２０１２－２１０４８号公報Japanese Patent Application Laid-Open No. 2012-21048 国際公開第２０１２／１０８３９０号International Publication No. 2012/108390
　本発明者らにより、セルロース原料をイオン液体に溶解し、生産性よく紡糸する技術は確立されたものの、紡糸された再生セルロース長繊維について、複合材や電材として利用するための強度、弾性率についてはこれまで検討されていなかった。 Although the present inventors have established a technique for dissolving cellulose raw material in an ionic liquid and spinning it with high productivity, the strength and elastic modulus for use as a composite material and electrical material for spun regenerated cellulose long fibers Has not been studied so far.
　本発明は、生産性良く、高強度かつ高弾性な再生セルロース長繊維を得ることを課題とする。 An object of the present invention is to obtain a regenerated cellulose long fiber with high productivity and high strength and high elasticity.
　本発明は、セルロース原料をイオン液体に溶解して、紡糸することにより得られる再生セルロース長繊維であって、平均重合度が５００以上３０００以下、平均繊維径が３０μｍ以下であることを特徴とする高強度かつ高弾性セルロース長繊維である。 The present invention is a regenerated cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid and spinning, wherein the average degree of polymerization is 500 or more and 3000 or less, and the average fiber diameter is 30 μm or less. It is a high strength and high elasticity cellulose continuous fiber.
　本発明において、高強度かつ高弾性セルロース長繊維とは、少なくとも引張強度が０．５５ＧＰａ以上、引張弾性率が３５ＧＰａ以上であるものをいう。 In the present invention, the high-strength and high-elasticity cellulose continuous fiber means one having at least a tensile strength of 0.55 GPa or more and a tensile elastic modulus of 35 GPa or more.
　本発明者らは、セルロース原料をイオン液体に溶解して紡糸することにより得られる再生セルロース長繊維は、平均繊維径が３０μｍ以下の細い繊維として紡糸することにより、引張強度が０．５５ＧＰａ以上、引張弾性率が３５ＧＰａ以上の高強度かつ高弾性セルロース長繊維となることを明らかにした。 The inventors of the present invention have obtained a regenerated cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid and spinning it, and spinning it as a thin fiber having an average fiber diameter of 30 μm or less, whereby a tensile strength of 0.55 GPa or more, It has been clarified that the tensile elastic modulus is high strength and high elasticity cellulose long fiber of 35 GPa or more.
　再生セルロース繊維の繊維径と引張強度及び引張弾性率との間に相関があるという報告はこれまでになく、本発明者らが初めて見出したことである。また、イオン液体にセルロース原料を溶解させたセルロース溶液を用いて細い長繊維を得ることは高度な技術であるが、ノズル径、紡糸速度や延伸等の紡糸条件を制御することにより平均繊維径３０μｍ以下の繊維を得ることができる。さらに、本発明者らは、イオン液体に溶解した平均重合度が５００以上３０００以下のセルロースであれば、生産性良く長繊維を紡糸することができ、繊維径を調節することにより、高強度かつ高弾性セルロース長繊維を紡糸することができることを見出した。 There has never been a report that there is a correlation between the fiber diameter of the regenerated cellulose fiber, the tensile strength, and the tensile elastic modulus, and the present inventors have found for the first time. In addition, it is an advanced technique to obtain fine long fibers using a cellulose solution in which a cellulose raw material is dissolved in an ionic liquid, but the average fiber diameter is 30 μm by controlling the spinning conditions such as nozzle diameter, spinning speed and stretching. The following fibers can be obtained. Furthermore, the present inventors can spin long fibers with high productivity if the average polymerization degree dissolved in the ionic liquid is 500 or more and 3000 or less, and by adjusting the fiber diameter, It has been found that highly elastic cellulose filaments can be spun.
　さらに、本発明の高強度かつ高弾性セルロース長繊維は、分子内水素結合度が４２％以上６０％以下であることを特徴とする。 Furthermore, the high-strength and high-elasticity cellulose long fiber of the present invention is characterized in that the intramolecular hydrogen bond degree is 42% or more and 60% or less.
　分子内水素結合度はセルロース分子内において隣り合うグルコース同士の結合力を示し、その値が高いほどより密な構造を有していると考えられている。分子内水素結合度が４２％以上６０％以下であれば、引張強度が０．５５ＧＰａ以上、引張弾性率３５ＧＰａ以上の高強度かつ高弾性セルロース長繊維を実現できる。 The degree of intramolecular hydrogen bonding indicates the bonding strength between adjacent glucose molecules in the cellulose molecule, and it is considered that the higher the value, the denser the structure. When the intramolecular hydrogen bond degree is 42% or more and 60% or less, a high strength and highly elastic cellulose continuous fiber having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more can be realized.
　また、本発明の高強度かつ高弾性セルロース長繊維は、複屈折度が６８Δ×１０－３以上９０Δ×１０－３以下であることを特徴とする。 In addition, the high-strength and high-elasticity cellulose continuous fiber of the present invention is characterized in that the birefringence is 68Δ × 10 −3 or more and 90Δ × 10 −3 or less.
　複屈折度は繊維を形成している結晶構造および非結晶構造からなる全体構造における分子配向性と相関があると言われている。複屈折度が６８Δ×１０－３以上９０Δ×１０－３以下であれば、引張強度が０．５５ＧＰａ以上、引張弾性率３５ＧＰａ以上の高強度かつ高弾性セルロース長繊維を実現できる。 The birefringence is said to correlate with the molecular orientation in the entire structure consisting of a crystalline structure and an amorphous structure forming the fiber. When the birefringence is 68Δ × 10 −3 or more and 90Δ × 10 −3 or less, it is possible to realize a high-strength and highly elastic cellulose filament having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more.
　また、本発明の高強度かつ高弾性セルロース長繊維は、分子内水素結合度が４５％以上６０％以下であることを特徴とする。 The high-strength and high-elasticity cellulose continuous fiber of the present invention is characterized by having an intramolecular hydrogen bond degree of 45% or more and 60% or less.
　分子内水素結合度が４５％以上６０％以下であれば、引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上の高強度かつ高弾性セルロース長繊維を得ることができる。引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上の繊維であれば、強化繊維や基材として用いたときにガラス繊維と同等以上の特性を発揮することができる。 If the degree of intramolecular hydrogen bonding is 45% or more and 60% or less, a high-strength and highly elastic cellulose continuous fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more can be obtained. If the fiber has a tensile strength of 0.80 GPa or more and a tensile elastic modulus of 45 GPa or more, it can exhibit characteristics equivalent to or higher than those of glass fibers when used as a reinforcing fiber or a substrate.
　さらに、本発明の高強度かつ高弾性セルロース長繊維は、複屈折度が７０Δ×１０－３以上９０Δ×１０－３以下であることを特徴とする。 Furthermore, the high-strength and highly elastic cellulose continuous fiber of the present invention is characterized in that the birefringence is 70Δ × 10 −3 or more and 90Δ × 10 −3 or less.
　複屈折度が７０Δ×１０－３以上９０Δ×１０－３以下であれば、引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上の高強度かつ高弾性セルロース長繊維を得ることができる。引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上の繊維であれば、強化繊維や基材として用いたときにガラス繊維と同等以上の特性を発揮することができる。 When the birefringence is 70Δ × 10 −3 or more and 90Δ × 10 −3 or less, a high-strength and highly elastic cellulose continuous fiber having a tensile strength of 0.80 GPa or more and a tensile modulus of 45 GPa or more can be obtained. If the fiber has a tensile strength of 0.80 GPa or more and a tensile elastic modulus of 45 GPa or more, it can exhibit characteristics equivalent to or higher than those of glass fibers when used as a reinforcing fiber or a substrate.
　さらに、本発明の高強度かつ高弾性セルロース長繊維を紡糸する方法は、セルロース原料をイオン液体に平均重合度が５００以上３０００以下になるように溶解して、平均繊維径が３０μｍ以下になるように紡糸することを特徴とする。 Further, in the method of spinning high-strength and high-elasticity cellulose long fibers of the present invention, the cellulose raw material is dissolved in an ionic liquid so that the average degree of polymerization is 500 or more and 3000 or less so that the average fiber diameter is 30 μm or less. It is characterized by being spun into
　セルロース原料をイオン液体に平均重合度が５００以上３０００以下になるように溶解することにより、平均繊維径が３０μｍ以下の繊維を工業的に安定して紡糸することが可能となり、引張弾性率が３５ＧＰａ以上である高強度かつ高弾性セルロース長繊維を得ることができる。 By dissolving the cellulose raw material in the ionic liquid so that the average degree of polymerization is 500 or more and 3000 or less, fibers having an average fiber diameter of 30 μm or less can be industrially spun, and the tensile elastic modulus is 35 GPa. The high-strength and high-elasticity cellulose long fibers as described above can be obtained.
　また、本発明の繊維強化複合材料は、高強度かつ高弾性セルロース長繊維と樹脂を混合することによって得ることを特徴とする。 The fiber-reinforced composite material of the present invention is characterized by being obtained by mixing high-strength and high-elastic cellulose long fibers and a resin.
　本発明の高強度かつ高弾性セルロース長繊維を樹脂と混合することによって、ガラス繊維を強化繊維として混合した複合材料と同程度以上の強度を備えた繊維強化複合材料を得ることができる。 By mixing the high-strength and high-elastic cellulose long fibers of the present invention with a resin, a fiber-reinforced composite material having a strength equal to or higher than that of a composite material in which glass fibers are mixed as reinforcing fibers can be obtained.
　以下、実施例を示しながら本発明を説明する。本発明で高強度かつ高弾性セルロース長繊維というのは、引張強度０．５５ＧＰａ以上、引張弾性率３５ＧＰａ以上のものをいう。また、本明細書では、長繊維とは５ｍ以上の繊維をいうが、生産性良く紡糸するためには１００００ｍ以上切断せず、連続して紡糸できることが望ましい。 Hereinafter, the present invention will be described with reference to examples. In the present invention, the high-strength and high-elasticity cellulose long fiber refers to those having a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more. Further, in this specification, the long fiber means a fiber of 5 m or longer. However, in order to perform spinning with high productivity, it is desirable that continuous spinning is possible without cutting 10,000 m or longer.
　また、本発明の高強度かつ高弾性セルロース長繊維は、平均重合度が５００以上３０００以下、平均繊維径が３０μｍ以下であることを特徴とする。本発明者らは、平均繊維径と繊維の強度との間に相関があることを見出し、平均繊維径が３０μｍ以下であると、引張強度が０．５５ＧＰａ以上、引張弾性率が３５ＧＰａ以上となることを明らかにした。引張弾性率が３５ＧＰａ以上であれば、ガラス繊維とほぼ同等の比弾性率を有することから、ガラス繊維の代替として充分に機能する。 Further, the high-strength and highly elastic cellulose long fiber of the present invention is characterized by having an average degree of polymerization of 500 to 3000 and an average fiber diameter of 30 μm or less. The present inventors have found that there is a correlation between the average fiber diameter and the fiber strength, and when the average fiber diameter is 30 μm or less, the tensile strength is 0.55 GPa or more and the tensile elastic modulus is 35 GPa or more. It revealed that. If the tensile elastic modulus is 35 GPa or more, it has a specific elastic modulus substantially equivalent to that of glass fiber, and thus functions sufficiently as a substitute for glass fiber.
　また、平均繊維径が２２μｍ以下であることが、引張強度が０．７５ＧＰａ以上、引張弾性率が４０ＧＰａ以上となることから好ましく、平均繊維径が２０μｍ以下であることが、引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上となることからより好ましく、平均繊維径が１２μｍ以下であることが、引張強度が０．９５ＧＰａ以上、引張弾性率が５０ＧＰａ以上となることからさらに好ましく、平均繊維径が６μｍ以下であることが、引張強度が１．１０ＧＰａ以上、引張弾性率が５５ＧＰａ以上となることから特に好ましく、平均繊維径が４μｍ以下であることが、引張強度が１．５０ＧＰａ以上、引張弾性率が６０ＧＰａ以上となることから最も好ましい。ここで、本発明の高強度かつ高弾性セルロース長繊維の平均繊維径の下限値としては、製造の困難性の観点から、現時点では１μｍを挙げることができる。 The average fiber diameter is preferably 22 μm or less because the tensile strength is 0.75 GPa or more and the tensile modulus is 40 GPa or more. The average fiber diameter is 20 μm or less, and the tensile strength is 0.80 GPa. As described above, the tensile modulus is more preferably 45 GPa or more, and the average fiber diameter is preferably 12 μm or less, more preferably 0.95 GPa or more and the tensile modulus is 50 GPa or more. Is preferably 6 μm or less, since the tensile strength is 1.10 GPa or more and the tensile modulus is 55 GPa or more, and the average fiber diameter is 4 μm or less, the tensile strength is 1.50 GPa or more, and the tensile elasticity is The rate is most preferable because it is 60 GPa or more. Here, as a lower limit value of the average fiber diameter of the high-strength and high-elasticity cellulose continuous fiber of the present invention, 1 μm can be mentioned at present from the viewpoint of manufacturing difficulty.
　本発明の高強度かつ高弾性セルロース長繊維は、平均重合度が５００以上３０００以下、平均繊維径が３０μｍ以下である。平均重合度が３０００を超すと、イオン液体に溶解しにくいことから、未溶解物による影響やセルロース溶液粘度が高くなり過ぎるため、安定的に細い繊維を紡糸することが困難になる。また、平均重合度は５００以下であると引張強度、引張弾性率の高い繊維を紡糸することができない。 The high-strength and highly elastic cellulose filaments of the present invention have an average degree of polymerization of 500 to 3000 and an average fiber diameter of 30 μm or less. If the average degree of polymerization exceeds 3000, it is difficult to dissolve in the ionic liquid, and therefore, the influence of undissolved substances and the viscosity of the cellulose solution become too high, so that it is difficult to stably spin fine fibers. Further, if the average degree of polymerization is 500 or less, fibers having high tensile strength and high tensile modulus cannot be spun.
　さらに、本発明の高強度かつ高弾性セルロース長繊維は平均重合度が５００以上２０００以下であることが紡糸性の観点から好ましく、平均重合度が６００以上１８００以下であることが、優れた紡糸性、引張強度、引張弾性率を備えた繊維を得ることができることからさらに好ましい。より細い糸を得るためには、平均重合度が小さい方が紡糸しやすいが、高強度かつ高弾性セルロース長繊維を得るためには、ある程度の平均重合度が必要である。上記平均重合度の範囲であれば、紡糸性良く、高強度かつ高弾性なセルロース長繊維を得ることができる。 Further, the high-strength and highly elastic cellulose continuous fiber of the present invention preferably has an average degree of polymerization of 500 or more and 2000 or less from the viewpoint of spinnability, and an average degree of polymerization of 600 or more and 1800 or less is excellent spinnability. Further, it is more preferable because a fiber having tensile strength and tensile elastic modulus can be obtained. In order to obtain a finer yarn, the smaller the average degree of polymerization, the easier it is to spin. However, in order to obtain a high strength and highly elastic cellulose filament, a certain degree of average degree of polymerization is required. When the average degree of polymerization is within the above range, it is possible to obtain cellulose continuous fibers having good spinnability and high strength and high elasticity.
　本発明の高強度かつ高弾性セルロース長繊維は、分子内水素結合度が４２％以上６０％以下であれば、引張強度が０．５５ＧＰａ以上、引張弾性率が３５ＧＰａ以上であり、さらに、分子内水素結合度が４４％以上６０％以下であれば、引張強度が０．７０ＧＰａ以上、引張弾性率が４０ＧＰａ以上となることから好ましく、分子内水素結合度が４５％以上６０％以下であることが、引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上となることからより好ましい。 When the intramolecular hydrogen bond degree is 42% or more and 60% or less, the high-strength and highly elastic cellulose long fiber of the present invention has a tensile strength of 0.55 GPa or more and a tensile modulus of 35 GPa or more. When the hydrogen bond degree is 44% or more and 60% or less, the tensile strength is preferably 0.70 GPa or more and the tensile modulus is 40 GPa or more, and the intramolecular hydrogen bond degree is 45% or more and 60% or less. More preferably, the tensile strength is 0.80 GPa or more and the tensile modulus is 45 GPa or more.
　本発明の高強度かつ高弾性セルロース長繊維は、複屈折度が６８Δ×１０－３以上９０Δ×１０－３以下であれば、引張強度が０．５５ＧＰａ以上、引張弾性率が３５ＧＰａ以上であり、さらに、複屈折度が６９Δ×１０－３以上９０Δ×１０－３以下であることが、引張強度が０．７５ＧＰａ以上、引張弾性率が４０ＧＰａ以上となることから好ましく、複屈折度が７０Δ×１０－３以上９０Δ×１０－３以下であることが、引張強度が０．８０ＧＰａ以上、引張弾性率が４５ＧＰａ以上となることからより好ましく、複屈折度が７１Δ×１０－３以上９０Δ×１０－３以下であることが、引張強度が１．００ＧＰａ以上、引張弾性率が５０ＧＰａ以上となることからさらに好ましく、複屈折度が７４Δ×１０－３以上９０Δ×１０－３以下であることが、引張強度が１．０５ＧＰａ以上、引張弾性率が５３ＧＰａ以上となることから特に好ましく、複屈折度が８０Δ×１０－３以上９０Δ×１０－３以下であることが、引張強度が１．５０ＧＰａ以上、引張弾性率が６０ＧＰａ以上となることから最も好ましい。 The high-strength and highly elastic cellulose continuous fiber of the present invention has a tensile strength of 0.55 GPa or more and a tensile elastic modulus of 35 GPa or more if the birefringence is 68Δ × 10 −3 or more and 90Δ × 10 −3 or less. Further, the birefringence is preferably 69Δ × 10 −3 or more and 90Δ × 10 −3 or less because the tensile strength is 0.75 GPa or more and the tensile elastic modulus is 40 GPa or more, and the birefringence is 70Δ × 10. −3 to 90Δ × 10 −3 is more preferable because the tensile strength is 0.80 GPa or more and the tensile modulus is 45 GPa or more, and the birefringence is 71Δ × 10 −3 or more and 90Δ × 10 −3. or less is, a tensile strength above 1.00GPa, tensile more preferably from becoming a more 50GPa modulus, degree birefringence 74Δ × 10 -3 or more 90Δ × 10 -3 der less It tensile strength above 1.05GPa, particularly preferred since the tensile modulus is equal to or greater than 53GPa, that the degree of birefringence is less than 80Δ × 10 -3 or more 90Δ × 10 -3, the tensile strength is 1. The most preferable is 50 GPa or more and the tensile elastic modulus is 60 GPa or more.
　ここで、本発明の高強度かつ高弾性セルロース長繊維は、平均重合度が７００以上２０００以下、平均繊維径が６μｍ以下、分子内水素結合度が４９％以上６０％以下、複屈折度が７４Δ×１０－３以上９０Δ×１０－３以下であることが、引張強度が１．１０ＧＰａ以上、引張弾性率が５５ＧＰａ以上となることから特に好ましく、平均重合度が７００以上２０００以下、平均繊維径が４μｍ以下、分子内水素結合度が５０％以上６０％以下、複屈折度が８０Δ×１０－３以上９０Δ×１０－３以下であることが最も好ましい。 Here, the high-strength and highly elastic cellulose long fiber of the present invention has an average degree of polymerization of 700 to 2000, an average fiber diameter of 6 μm or less, an intramolecular hydrogen bond degree of 49% to 60%, and a birefringence of 74Δ. It is particularly preferable that the tensile strength is 1.10 GPa or more and the tensile elastic modulus is 55 GPa or more, and the average degree of polymerization is 700 to 2000 and the average fiber diameter is × 10 −3 or more and 90Δ × 10 −3 or less. Most preferably, it is 4 μm or less, the degree of intramolecular hydrogen bonding is 50% or more and 60% or less, and the birefringence is 80Δ × 10 −3 or more and 90Δ × 10 −3 or less.
　［高強度かつ高弾性セルロース長繊維の製造方法］
　本発明の高強度かつ高弾性セルロース長繊維は、セルロース原料をイミダゾリウム化合物からなるイオン液体に溶解してセルロース溶液を得る。次にセルロース溶液をイミダゾリウム化合物が可溶であると共にセルロースが不溶である凝固液中に押し出して、セルロース溶液に含まれるセルロースを凝固させて製造する。 [Method for producing high-strength and high-elasticity cellulose continuous fiber]
The high-strength and highly elastic 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 extruded into a coagulating liquid in which the imidazolium compound is soluble and insoluble in cellulose, and the cellulose contained in the cellulose solution is coagulated to produce.
　セルロース原料としては、基本的にどのようなものでも良く、例えば木材パルプ、コットン、コットンリンター、麻、竹、アバカ等の天然セルロース原料やレーヨンやキュプラ、リヨセル等の再生セルロース繊維、また、それらからなる紙や衣服をセルロース原料として再利用して用いても良い。経済性の観点からすれば天然セルロース原料が好ましく、その中でも溶解パルプ、コットンリンターや竹が、セルロース純度やセルロース平均重合度が高いことなどから望ましい。 The cellulose raw material may be basically any material, for example, natural cellulose raw materials such as wood pulp, cotton, cotton linter, hemp, bamboo, abaca, regenerated cellulose fibers such as rayon, cupra, lyocell, and the like. The resulting paper or clothing may be reused as a cellulose raw material. From the viewpoint of economy, natural cellulose raw materials are preferable, and among them, dissolving pulp, cotton linter and bamboo are preferable because of high cellulose purity and average cellulose polymerization degree.
　セルロース原料のセルロース純度が高いと、セルロース原料に含まれる油脂分やリグニン、ヘミセルロース等の夾雑物が少なく、セルロース溶液の均質性や紡糸時の曳糸性、延伸性を阻害しない。 When the cellulose purity of the cellulose raw material is high, there are few impurities such as fats and oils, lignin and hemicellulose contained in the cellulose raw material, and the homogeneity of the cellulose solution, the spinnability during spinning, and the stretchability are not hindered.
　また、セルロースの平均重合度は、得られる繊維の物性を考慮すると、最低５００以上が好ましく、溶解性から３０００以下が望ましい。 In addition, the average degree of polymerization of cellulose is preferably at least 500 or more, and preferably 3000 or less in view of solubility, considering the physical properties of the obtained fiber.
　イミダゾリウム化合物からなるイオン液体としては、１－エチル－３－メチルイミダゾリウムアセテート、１－ブチル－３－メチルイミダゾリウムクロライド、１－エチル－３－メチルイミダゾリウムジエチル－ホスフェート、１－ブチル－３－メチルイミダゾリウムアセテート、１,３－ジメチルイミダゾリウムアセテート、１－エチル－３－メチルイミダゾリウムプロピオネート、１－アリル－３－メチルイミダゾリウムクロライド等を挙げることができる。好ましくは、１－エチル－３－メチルイミダゾリウムアセテート、１－ブチル－３－メチルイミダゾリウムクロライド、１－エチル－３－メチルイミダゾリウムジエチルフォスフェートを挙げることができる。 Examples of the ionic liquid comprising an imidazolium compound include 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-butyl-3. -Methylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1-ethyl-3-methylimidazolium propionate, 1-allyl-3-methylimidazolium chloride and the like. Preferred examples include 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium diethyl phosphate.
　これらのイオン液体を用いれば、平均重合度８００以上の比較的大きな平均重合度のセルロースも容易に溶解することができる。 If these ionic liquids are used, cellulose having a relatively large average degree of polymerization having an average degree of polymerization of 800 or more can be easily dissolved.
　セルロースの平均重合度やイオン液体の種類によって、溶解時間や溶解温度を調整し、セルロース原料を均質な溶解液となるまで溶解すればよい。 The dissolution time and dissolution temperature may be adjusted according to the average degree of polymerization of cellulose and the type of ionic liquid, and the cellulose raw material may be dissolved until it becomes a homogeneous solution.
　加熱手段は任意であるが、オーブンによる加熱、水浴や油浴による加熱、マイクロウェーブによる加熱などの一般的な加熱手段を用いればよい。 The heating means is arbitrary, but general heating means such as heating with an oven, heating with a water bath or oil bath, heating with a microwave, etc. may be used.
　また、加熱にあたっては、セルロース原料の溶解を促進するために、撹拌を行うことが好ましい。撹拌手段も任意であり、撹拌子や撹拌羽根による機械的撹拌、容器の振盪による撹拌、超音波照射による撹拌などに代表される公知の撹拌法の中から、スケール等に応じて適切な手段を採用すればよい。 Further, in heating, it is preferable to perform stirring in order to promote dissolution of the cellulose raw material. Stirring means are also optional, and among the known stirring methods represented by mechanical stirring with a stirrer or stirring blade, stirring by shaking the container, stirring by ultrasonic irradiation, etc., an appropriate means according to the scale etc. Adopt it.
　さらに、加熱溶解時において、セルロースの酸化・分解を抑制するために、窒素などの不活性ガス雰囲気下で溶解させることが好ましい。 Furthermore, it is preferable to dissolve in an inert gas atmosphere such as nitrogen in order to suppress oxidation / decomposition of cellulose during dissolution by heating.
　セルロース原料をイオン液体に溶解させて得られたセルロース溶液は、そのまま後の工程に用いてもよいが、溶液中に未溶解分や不溶解分が残存している場合、これらをろ過してから用いてもよい。 The cellulose solution obtained by dissolving the cellulose raw material in the ionic liquid may be used as it is in the subsequent step, but if undissolved or insoluble matter remains in the solution, after filtering these It may be used.
　また、得られたセルロース溶液は即時に使用してもよいが、成形性、並びに成形物の物性等の諸特性を維持できる限り、所定時間保存した後に使用してもよい。特に、溶解後、室温以下の温度で吸湿に注意しながら保存すると、長期間保存することができる。 The obtained cellulose solution may be used immediately, but may be used after being stored for a predetermined time as long as various properties such as moldability and physical properties of the molded product can be maintained. In particular, if the product is stored at a temperature below room temperature while paying attention to moisture absorption, it can be stored for a long time.
　溶解したセルロースはノズルから押出された後、凝固液中に浸漬させることにより紡糸する。凝固液は、０℃以上１００℃以下の範囲の温度の水、又は－４０℃以上１００℃以下の範囲の温度の低級アルコール、極性溶媒、無極性溶媒等を用いることができる。経済性および作業環境性を考えると、水を用いることが好ましい。なお、低級アルコールとは炭素数１以上５以下のアルコールをいう。 The dissolved cellulose is extruded from a nozzle and then spun by immersing it in a coagulation liquid. As the coagulation liquid, water having a temperature in the range of 0 ° C. or higher and 100 ° C. or lower, or a lower alcohol, a polar solvent, a nonpolar solvent, or the like having a temperature in the range of −40 ° C. or higher and 100 ° C. or lower can be used. In view of economy and work environment, it is preferable to use water. The lower alcohol means an alcohol having 1 to 5 carbon atoms.
　紡糸した再生セルロース長繊維は水で洗浄するが、洗浄後のイオン液体の残存量は、再生セルロース長繊維の元素分析によって検出される窒素量からイオン液体量に換算すると１００００ｐｐｍ以下となっている。 The spun regenerated cellulose long fiber is washed with water, but the remaining amount of the ionic liquid after washing is 10000 ppm or less when converted from the nitrogen amount detected by elemental analysis of the regenerated cellulose long fiber to the ionic liquid amount.
　繊維径の異なる再生セルロース長繊維を製造するためには、押出流量を制御しながら径の異なるノズルからセルロース溶液を押出し、巻取速度や延伸条件を制御しながら紡糸すればよい。例えば、２０μｍの繊維径のセルロース繊維は、直径０．１５ｍｍのノズルを用い、０．０１～１ｍＬ／分の範囲で押出流量を固定しつつ、繊維径が２０μｍになるまで徐々に巻取速度と延伸比を上げていきながら紡糸をすることで得られる。 In order to produce regenerated cellulose long fibers having different fiber diameters, the cellulose solution may be extruded from nozzles having different diameters while controlling the extrusion flow rate, and spinning may be performed while controlling the winding speed and stretching conditions. For example, for a cellulose fiber having a fiber diameter of 20 μm, a winding speed is gradually increased until the fiber diameter reaches 20 μm while fixing an extrusion flow rate in a range of 0.01 to 1 mL / min using a nozzle having a diameter of 0.15 mm. It can be obtained by spinning while increasing the draw ratio.
　また、繊維強化複合材料を作製する際には、熱可塑性樹脂及び熱硬化性樹脂からなる群より選ばれる少なくとも１つの樹脂と高強度かつ高弾性セルロース長繊維とを混合する。繊維強化複合材料における熱可塑性樹脂としては、ポリアミド（ナイロン）、ポリアセタール、ポリカーボネート、ポリ塩化ビニル、ＡＢＳ、ポリサルフォン、ポリエチレン、ポリプロピレン、ポリスチレン、（メタ）アクリル樹脂、フッ素樹脂、メラミン樹脂が例示でき、熱硬化性樹脂としては、不飽和ポリエステル樹脂、エポキシ樹脂、メラミン樹脂、フェノール樹脂が例示できる。また、繊維強化複合材料が熱硬化性樹脂を含む場合は、繊維強化複合材料には当該熱硬化性樹脂が完全硬化した繊維強化複合材料の他、熱硬化性樹脂を半硬化の状態にしたプリプレグをも含むものとする。なお、繊維強化複合材料は、必要に応じて、低収縮剤、難燃剤、難燃助剤、可塑剤、酸化防止剤、紫外線吸収剤、着色剤、顔料、充填剤等の添加剤を含有していてもよい。 Further, when producing a fiber reinforced composite material, at least one resin selected from the group consisting of a thermoplastic resin and a thermosetting resin and a high-strength and highly elastic cellulose long fiber are mixed. Examples of the thermoplastic resin in the fiber reinforced composite material include polyamide (nylon), polyacetal, polycarbonate, polyvinyl chloride, ABS, polysulfone, polyethylene, polypropylene, polystyrene, (meth) acrylic resin, fluororesin, and melamine resin. Examples of the curable resin include unsaturated polyester resins, epoxy resins, melamine resins, and phenol resins. When the fiber reinforced composite material includes a thermosetting resin, the fiber reinforced composite material includes a prepreg in which the thermosetting resin is semi-cured in addition to the fiber reinforced composite material in which the thermosetting resin is completely cured. Is also included. The fiber reinforced composite material contains additives such as a low shrinkage agent, a flame retardant, a flame retardant aid, a plasticizer, an antioxidant, an ultraviolet absorber, a colorant, a pigment, and a filler as necessary. It may be.
　［再生セルロース長繊維の物性の測定］
　上記方法により得られたセルロース繊維の物性は以下の方法で測定し、表１にまとめた。 [Measurement of physical properties of regenerated cellulose filaments]
The physical properties of the cellulose fibers obtained by the above method were measured by the following methods and summarized in Table 1.
　（平均繊維径）
　平均繊維径は、走査型電子顕微鏡（日立製作所製、ＳＮ－３４００Ｎ）により測定した。再生セルロース長繊維切片（繊維長２０ｍｍ）から１０点の繊維径を測長し、その平均値を平均繊維径とした。 (Average fiber diameter)
The average fiber diameter was measured with a scanning electron microscope (manufactured by Hitachi, Ltd., SN-3400N). Ten fiber diameters were measured from the regenerated cellulose long fiber slice (fiber length 20 mm), and the average value was defined as the average fiber diameter.
　（引張強度、引張弾性率、伸度）
　引張強度、引張弾性率、伸度は引張試験機（オリエンテック製、ＴＥＮＳＩＬＯＮ　ＲＴＣ－１１５０Ａ）を用い、試験片長：５０ｍｍ、引張試験速度：５ｍｍ／ｍｉｎ、ロードセル荷重：２Ｎの条件で試験を行った。試験片は１１０℃、１時間、絶乾処理を行い、デシケータ内で室温まで冷却後、評価を行った。 (Tensile strength, tensile modulus, elongation)
Tensile strength, tensile modulus, and elongation were tested using a tensile tester (Orientec, TENSILON RTC-1150A) under the conditions of test piece length: 50 mm, tensile test speed: 5 mm / min, load cell load: 2N. . The test piece was subjected to an absolute drying treatment at 110 ° C. for 1 hour, and was evaluated after cooling to room temperature in a desiccator.
　（複屈折度）
　複屈折度の測定は、偏光顕微鏡（オリンパス社製、ＢＨ－２）により、５４６ｎｍの入射光を用い、コンペンセータ法により測定を実施し、下記計算式より求めた。なお、本発明において、複屈折度は、本方法により測定される値として定義される。
Δｎ＝｛ｎλ+ａλ（ｘ－１６０５）｝／ｄ
ｎ：繊維断面に見られる縞数、λ：入射光の波長（５４６ｎｍ）、ｄ：繊維の厚み（ｎｍ）、ａλ：光源とコンペンセータによって決まる定数（０．９７）、ｘ：読み取り値
　（平均重合度）
　セルロースの平均重合度は、ＴＡＰＰＩ　Ｔ２３０標準法（粘度法）により平均分子量を測定し、測定された平均分子量をセルロースの構成単位であるグルコースの分子量で除することにより算定した。なお、本発明において、平均重合度は、本方法により算定される値として定義される。 (Birefringence)
The birefringence was measured by a compensator method using an incident light of 546 nm with a polarizing microscope (Olympus, BH-2), and obtained from the following calculation formula. In the present invention, the birefringence is defined as a value measured by this method.
Δn = {nλ + aλ (x−1605)} / d
n: number of fringes found in the fiber cross section, λ: wavelength of incident light (546 nm), d: fiber thickness (nm), aλ: constant determined by light source and compensator (0.97), x: reading value (average polymerization) Every time)
The average degree of polymerization of cellulose was calculated by measuring the average molecular weight by the TAPPI T230 standard method (viscosity method) and dividing the measured average molecular weight by the molecular weight of glucose, which is a constituent unit of cellulose. In the present invention, the average degree of polymerization is defined as a value calculated by this method.
　（結晶配向度）
　結晶配向度の測定は、JIS K0131に従い行った。具体的には、Ｘ線回折装置であるリガク社製、ＲＯＴＡ－Ｆｌｅｘ　ＲＴＰ－３００を用いて透過法にて測定を行った。繊維試料台にセットした再生セルロース長繊維にＸ線を３０分照射し、イメージングプレート検出器で検出し、検出値を読み取り装置（リガク社製、Ｒ－ＡＸＩＳ　ＤＳ３Ｃ）で解析することにより求めた。なお、本発明において、結晶配向度は、本方法により測定される値として定義される。 (Crystal orientation)
The crystal orientation was measured according to JIS K0131. Specifically, the measurement was performed by the transmission method using a ROTA-Flex RTP-300 manufactured by Rigaku Corporation which is an X-ray diffractometer. The regenerated cellulose long fiber set on the fiber sample stage was irradiated with X-rays for 30 minutes, detected with an imaging plate detector, and the detected value was determined by analyzing with a reading device (R-AXIS DS3C, manufactured by Rigaku Corporation). In the present invention, the degree of crystal orientation is defined as a value measured by this method.
　（結晶化度）
　結晶化度の測定はＸ線回折装置であるリガク社製、Ｍｕｌｔｉ　Ｆｌｅｘを用いて反射法にて測定を行った。試料台に再生セルロース長繊維を載せ１２０ｒｐｍで試料台を回転させながら、Ｘ線を照射し、５°以上４０°以下の測定範囲で測定速度１°／ｍｉｎで、シンチレーションカウンターを用いて検出した。得られたスペクトルデータをもとにピーク分離法（面積法）を用いて結晶化度を算出した（非特許文献１）。なお、本発明において、結晶化度は、本方法により測定される値として定義される。 (Crystallinity)
The crystallinity was measured by a reflection method using a Multi Flex manufactured by Rigaku Corporation which is an X-ray diffractometer. While the regenerated cellulose long fiber was placed on the sample stage, the sample stage was rotated at 120 rpm, X-rays were irradiated, and detection was performed using a scintillation counter at a measurement speed of 1 ° / min in a measurement range of 5 ° to 40 °. Based on the obtained spectrum data, the crystallinity was calculated using a peak separation method (area method) (Non-patent Document 1). In the present invention, crystallinity is defined as a value measured by this method.
　（分子内水素結合度測定）
　分子内水素結合度は固体NMR測定装置であるＢｒｕｋｅｒ社製、ＡＶＡＮＣＥ３００を用いてＣＰＭＡＳ法にて測定を行った。観測核は13Ｃ（共鳴周波数75.4MHz）とし、MAS条件は３kHz、コンタクトタイムは２ミリセコンドとして検出を行った。なお、本発明において、分子内水素結合度は、本方法により測定される値として定義される。 (Intramolecular hydrogen bond measurement)
The intramolecular hydrogen bond degree was measured by CPMAS method using AVANCE300 manufactured by Bruker, which is a solid-state NMR measurement apparatus. The detection nucleus was 13 C (resonance frequency 75.4 MHz), the MAS condition was 3 kHz, and the contact time was 2 milliseconds. In the present invention, the degree of intramolecular hydrogen bonding is defined as a value measured by this method.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～８、及び比較例１及び２は、セルロース原料をイオン液体に溶解後、ノズルから押出すことにより紡糸した。その際、ノズル径や巻取速度、延伸条件などを変えることにより異なる径の繊維を得て、物性を測定したものである。 Examples 1 to 8 and Comparative Examples 1 and 2 were spun by dissolving a cellulose raw material in an ionic liquid and then extruding it from a nozzle. At that time, fibers having different diameters were obtained by changing the nozzle diameter, winding speed, stretching conditions, and the like, and the physical properties were measured.
　比較例１は平均重合度は８８０と本発明の範囲内であるが、平均繊維径が４１．０μｍと大きいもの、比較例２は平均重合度が本発明の範囲よりも小さいものを紡糸して得られた繊維の物性を測定した結果である。比較例３～５は本願発明の繊維径の範囲内の従来からある再生セルロース長繊維について物性を測定した結果を示している。比較例３はキュプラ、比較例４はレーヨン、比較例５はリヨセルを示す。 In Comparative Example 1, the average degree of polymerization is 880, which is within the range of the present invention, but the average fiber diameter is as large as 41.0 μm, and in Comparative Example 2, the average degree of polymerization is smaller than the range of the present invention. It is the result of having measured the physical property of the obtained fiber. Comparative Examples 3 to 5 show the results of measuring physical properties of conventional regenerated cellulose long fibers within the fiber diameter range of the present invention. Comparative Example 3 is a cupra, Comparative Example 4 is a rayon, and Comparative Example 5 is a lyocell.
　表１に示すように、セルロース原料をイオン液体に溶解し、紡糸することにより得られる再生セルロース長繊維は、平均繊維径が細くなればなるほど、引張強度及び引張弾性率が高くなる。 As shown in Table 1, the regenerated cellulose long fibers obtained by dissolving a cellulose raw material in an ionic liquid and spinning the finer the average fiber diameter, the higher the tensile strength and the tensile elastic modulus.
　特に、実施例１で示したように平均繊維径３．１μｍの細い再生セルロース長繊維では、引張強度１．５４ＧＰａ、引張弾性率６２．５ＧＰａと、Ｅガラスで製造したガラス繊維と同等以上の物性を備えている。 In particular, as shown in Example 1, a thin regenerated cellulose long fiber having an average fiber diameter of 3.1 μm has a tensile strength of 1.54 GPa, a tensile elastic modulus of 62.5 GPa, and physical properties equivalent to or higher than those of glass fiber produced from E glass. It has.
　また、比較例３～５に示すように、キュプラ、レーヨン、リヨセルといった、既存の再生セルロース長繊維についても解析を行ったが、本発明でいう高強度かつ高弾性の基準を満たすものはなかった。 In addition, as shown in Comparative Examples 3 to 5, the analysis was performed on the existing regenerated cellulose long fibers such as cupra, rayon, and lyocell, but none of them met the high strength and high elasticity criteria referred to in the present invention. .
　比較例３～５は、平均繊維径１０μｍ程度のキュプラ、レーヨン、リヨセルの引張強度、引張弾性率等の評価を示している。キュプラ等他の再生セルロース長繊維に関しても、本発明のセルロース原料をイオン液体に溶解し紡糸して得られた長繊維同様、繊維径が細くなるにしたがって高強度かつ高弾性になることも考えられる。 Comparative Examples 3 to 5 show evaluations such as the tensile strength and tensile modulus of cupra, rayon, and lyocell having an average fiber diameter of about 10 μm. As for other regenerated cellulose long fibers such as cupra, it is also possible that, as with the long fibers obtained by dissolving the cellulose raw material of the present invention in an ionic liquid and spinning, the strength and elasticity become higher as the fiber diameter becomes smaller. .
　しかしながら、実施例８に示す平均繊維径２７．９μｍの本発明の再生セルロース長繊維は、比較例３のキュプラと比較すると、約３倍の繊維径であるにもかかわらず、高い引張強度、引張弾性率が得られている。したがって、仮にキュプラ等、他の再生セルロース長繊維で３μｍ程度の細い繊維径のものが得られたとしても、本発明の再生セルロース長繊維ほど高強度かつ高弾性のものが得られるとは考えられない。 However, the regenerated cellulose long fiber of the present invention having an average fiber diameter of 27.9 μm shown in Example 8 has a high tensile strength and tensile strength even though the fiber diameter is about 3 times that of the cupra of Comparative Example 3. Elastic modulus is obtained. Therefore, even if another regenerated cellulose long fiber having a thin fiber diameter of about 3 μm, such as cupra, is obtained, it is considered that the regenerated cellulose long fiber of the present invention has a higher strength and higher elasticity. Absent.
　レーヨン等の再生セルロース長繊維は、紡糸時の諸条件（延伸、乾燥等）によってセルロースの結晶性に違いが生じたり、強酸や強アルカリ等による処理によって低重合度化されていたりするため、高い物性の再生セルロース長繊維が得られにくいものと考えられる。 Regenerated cellulose filaments such as rayon are high because of differences in crystallinity of cellulose due to various spinning conditions (stretching, drying, etc.), and low polymerization degree due to treatment with strong acid or strong alkali. It is considered that regenerated cellulose long fibers having physical properties are difficult to obtain.
　比較例２のイオン液体で溶解した平均重合度の低い再生セルロース長繊維では、細い繊維を紡糸しても高い物性の再生セルロース長繊維が得られないことからも、平均重合度は、高強度かつ高弾性セルロース長繊維を得るために重要な要素の１つである。また、イオン液体による溶解方法は比較的温和な溶解方法であることから、セルロースの平均重合度をあまり低下させることなく再生セルロース長繊維を得ることができる。 In the regenerated cellulose long fiber having a low average degree of polymerization dissolved in the ionic liquid of Comparative Example 2, since the regenerated cellulose long fiber having high physical properties cannot be obtained even when a thin fiber is spun, the average degree of polymerization is high and This is one of the important factors for obtaining highly elastic cellulose filaments. Further, since the dissolution method using an ionic liquid is a relatively mild dissolution method, regenerated cellulose long fibers can be obtained without significantly reducing the average degree of polymerization of cellulose.
　また、キュプラ等他の再生セルロース長繊維は、現在のところ本実施例の最小繊維径である３μｍ程度のものは市販されておらず、細い繊維を生産性良く得ることは難しいものと考えられる。 Moreover, as for other regenerated cellulose long fibers such as cupra, those having a minimum fiber diameter of about 3 μm in this example are not commercially available at present, and it is considered difficult to obtain thin fibers with high productivity.
　また、分子内水素結合度は、セルロース分子鎖間の水素と酸素がより密に結合していることを表す指標であるが、イオン液体で溶解し紡糸した高強度かつ高弾性セルロース長繊維においては、結晶化度、結晶配向度、引張強度、引張弾性率とも相関性が高いことが示された。一方、比較例３～５で示すように、他の方法で製造したセルロース繊維の場合には、必ずしも分子内水素結合度と引張強度、引張弾性率の間に強い相関が見られるわけではない。 In addition, the degree of intramolecular hydrogen bonding is an index indicating that hydrogen and oxygen are bonded more closely between cellulose molecular chains. In high-strength and high-elasticity cellulose long fibers dissolved and spun in an ionic liquid, It was also shown that the degree of crystallinity, the degree of crystal orientation, the tensile strength, and the tensile modulus are highly correlated. On the other hand, as shown in Comparative Examples 3 to 5, in the case of cellulose fibers produced by other methods, there is not always a strong correlation between the degree of intramolecular hydrogen bonding, tensile strength, and tensile modulus.
　以上、示してきたように、セルロース原料をイオン液体に溶解して、平均重合度が５００以上３０００以下、平均繊維径が３０μｍ以下に再生セルロース長繊維を紡糸することにより、繊維強化複合材料用の強化繊維やプリント配線板の基材としてガラス繊維の代替となり得るような高強度かつ高弾性セルロース長繊維を紡糸することが可能となった。 As described above, the cellulose raw material is dissolved in an ionic liquid, and the regenerated cellulose long fibers are spun to an average degree of polymerization of 500 to 3000 and an average fiber diameter of 30 μm or less. It has become possible to spin high-strength and high-elasticity cellulose long fibers that can replace glass fibers as a base material for reinforcing fibers and printed wiring boards.
　次に、実際に実施例４の再生セルロース長繊維を一方向に引き揃え、エポキシ樹脂を含浸させ、金型に引き込み、金型内で加熱硬化させた後、金型から脱型することで、繊維強化複合材料を作製し、曲げ弾性率、曲げ強度、熱膨張係数等の物性評価を行った（開発品）。コントロールとして一般的な再生セルロース長繊維であり、比較的物性も高いとされるキュプラ、Ｅガラス繊維を同様の繊維含有量で樹脂に混合し複合材料を作成した。結果を表２に示す。 Next, the regenerated cellulose filaments of Example 4 were actually aligned in one direction, impregnated with epoxy resin, drawn into the mold, heated and cured in the mold, and then removed from the mold. A fiber reinforced composite material was prepared and evaluated for physical properties such as flexural modulus, flexural strength, and thermal expansion coefficient (developed product). As a control, cupra and E glass fibers, which are general regenerated cellulose long fibers and have relatively high physical properties, were mixed with a resin at the same fiber content to prepare a composite material. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示すように、繊維強化複合材料としたときに、開発品の曲げ弾性率、熱膨張係数はＥガラス繊維を用いた場合とほぼ同等であった。再生セルロース長繊維を用い、ガラス繊維と同等の曲げ弾性率が得られたのは、本発明の再生セルロース長繊維が初めてであり、高弾性率、低熱膨張が求められるプリント配線板の基材や繊維強化複合材料用の強化繊維として、幅広い応用が期待される。 As shown in Table 2, when the fiber reinforced composite material was used, the flexural modulus and thermal expansion coefficient of the developed product were almost the same as when E glass fiber was used. The regenerated cellulose long fiber of the present invention was obtained for the first time using the regenerated cellulose long fiber, and the same bending elastic modulus as that of the glass fiber, and the substrate of the printed wiring board required to have high elastic modulus and low thermal expansion A wide range of applications are expected as reinforcing fibers for fiber-reinforced composite materials.
　以上示してきたように、本発明の高強度かつ高弾性セルロース長繊維は、従来のセルロース繊維と比べてはるかに高い引張強度と引張弾性率を示し、引張弾性率を比重で除した比弾性率についてはガラス繊維と同等以上になる。また、強化繊維や基材として樹脂に混合した場合にも、曲げ弾性率に優れ、熱膨張係数もＥガラスを用いた場合と同程度の繊維強化複合材料を得ることができる。 As described above, the high-strength and high-elasticity cellulose long fiber of the present invention exhibits a much higher tensile strength and tensile modulus than conventional cellulose fibers, and the specific modulus obtained by dividing the tensile modulus by specific gravity. Is equal to or better than glass fiber. Further, when mixed with resin as a reinforcing fiber or a base material, a fiber-reinforced composite material having an excellent bending elastic modulus and a thermal expansion coefficient similar to that when E glass is used can be obtained.

Claims (7)

  1. セルロース原料をイオン液体に溶解して、紡糸することにより得られるセルロース長繊維であって、
    　平均重合度が５００以上３０００以下、
    　平均繊維径が３０μｍ以下であることを特徴とする高強度かつ高弾性セルロース長繊維。     A cellulose long fiber obtained by dissolving a cellulose raw material in an ionic liquid and spinning,
    Average polymerization degree is 500 or more and 3000 or less,
    A high-strength and high-elasticity cellulose continuous fiber having an average fiber diameter of 30 μm or less.
  2. 　請求項１記載の高強度かつ高弾性セルロース長繊維であって、
    　分子内水素結合度が４２％以上６０％以下であることを特徴とする高強度かつ高弾性セルロース長繊維。     The high-strength and highly elastic cellulose filament according to claim 1,
    A high-strength and highly elastic cellulose long fiber having an intramolecular hydrogen bond degree of 42% or more and 60% or less.
  3. 　請求項１又は２記載の高強度かつ高弾性セルロース長繊維であって、
    　複屈折度が６８Δ×１０－３以上９０Δ×１０－３以下であることを特徴とする高強度かつ高弾性セルロース長繊維。     The high-strength and high-elasticity cellulose continuous fiber according to claim 1 or 2,
    A high-strength and highly elastic cellulose long fiber having a birefringence of 68Δ × 10 −3 or more and 90Δ × 10 −3 or less.
  4. 　請求項２又は３記載の高強度かつ高弾性セルロース長繊維であって、
    　分子内水素結合度が４５％以上６０％以下であることを特徴とする高強度かつ高弾性セルロース長繊維。     The high-strength and high-elasticity cellulose continuous fiber according to claim 2 or 3,
    A high-strength and highly elastic cellulose continuous fiber having an intramolecular hydrogen bond degree of 45% or more and 60% or less.
  5. 　請求項２～４いずれか１項記載の高強度かつ高弾性セルロース長繊維であって、
    　複屈折度が７０Δ×１０－３以上９０Δ×１０－３以下であることを特徴とする高強度かつ高弾性セルロース長繊維。     A high-strength and high-elasticity cellulose continuous fiber according to any one of claims 2 to 4,
    A high-strength and highly elastic cellulose continuous fiber having a birefringence of 70Δ × 10 −3 or more and 90Δ × 10 −3 or less.
  6. 　引張弾性率が３５ＧＰａ以上である高強度かつ高弾性セルロース長繊維を紡糸する方法であって、
    　セルロース原料をイオン液体に平均重合度が以上３０００以下になるように溶解し、
    　平均繊維径が３０μｍ以下になるように紡糸することを特徴とする高強度かつ高弾性セルロース長繊維を紡糸する方法。     A method of spinning a high-strength and high-elasticity cellulose continuous fiber having a tensile modulus of 35 GPa or more,
    Cellulose raw material is dissolved in an ionic liquid so that the average polymerization degree is 3000 or more and
    A method for spinning high-strength and high-elasticity cellulose continuous fibers, wherein spinning is performed so that an average fiber diameter is 30 μm or less.
  7. 　請求項１～５いずれか１項記載の高強度かつ高弾性セルロース長繊維と樹脂を混合することによって得ることを特徴とする繊維強化複合材料。
     
          A fiber-reinforced composite material obtained by mixing the high-strength and high-elasticity cellulose continuous fiber according to any one of claims 1 to 5 and a resin.

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