KR101960615B1 - Chitin Fiber With Novel Structure and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to chitin fibers comprising chitin nanofibers having a hierarchical structure. Chitin fibers according to the present invention has excellent mechanical properties. A centrifugal spinning process for manufacturing the chitin fibers simplifies a manufacturing process so that a large amount of fibers can be manufactured at a low cost, and particularly, allows chitin nanofibers included in the chitin fibers to be self-assembled, thereby being able to form the hierarchical structure.

Description

TECHNICAL FIELD [0001] The present invention relates to a chitin fiber having a novel structure,

The present invention relates to a chitin fiber characterized by having a hierarchical structure of chitin nanofibers contained in a chitin fiber, and more particularly, to a chitin fiber which forms a hierarchical structure by a centrifugal spinning process and exhibits excellent mechanical properties .

Nanofibers having a thickness of a half of a hair are used as materials for many fields because they can give miscibility with different materials. Melt blowing, electrospinning, etc. are known as methods for producing nanofibers, and natural polymers such as synthetic polymers or chitin are used as raw materials.

Chitin [poly (β- (1,4) -N-acetyl-Dglucosamine)] is a natural polymeric polysaccharide with molecular weight of 20,000 or more, which is the most abundant structural polymer on earth after celluloses and similar structure to cellulose of plants. It can be extracted from cell wall of higher plants, exoskeleton of crustaceans such as shrimp and crab, endoskeleton of mollusk such as squid, fungus. Chitin has been studied as a high molecular weight nanocomposite reinforcing material because of its high aspect ratio, multifunctional properties and excellent biocompatibility and biodegradability.

Korean Patent No. 10-0545404 (registered on Jan. 16, 2006, entitled "Nonwoven Fabrics Containing Chitin or Chitosan Nanofibers") manufactures chitin fibers through an electrospinning step, There is still a drawback that energy consumption is large because the high pressure collecting process and the solidification process are separately required after roughing, and there is still a drawback that scale-up is impossible and productivity is lacking.

Therefore, there is a need to develop a process for producing a large amount of fibers at a low cost by simplifying the process. Further, improvement of mechanical properties of chitin nanofiber is also required.

Korean Registered Patent No. 10-0545404 (registered on Jan. 16, 2006)

SUMMARY OF THE INVENTION The present invention has been made to overcome the problems of the prior art as described above, and the present inventors have made efforts to develop a method of producing chitin fibers through simple and cost-reduced processes. As a result, they have completed the centrifugal spinning process, Wherein the chitin nanofibers contained in the chitin nanofibers have a hierarchical structure.

In order to achieve the above object, the chitin fibers have a hierarchical structure in which chitin nanofibers are collectively aligned along a fiber axis. The diameter of the chitin nanofibers is not less than 3 nm and not more than 50 nm, and the diameter of the chitin fibers is not less than 500 nm and not more than 10 μm. The chitin fibers may be used as a component of a non-woven mat or membrane.

In order to accomplish the above object, there is provided a method for producing a chitin fiber comprising the steps of: preparing a spinning solution by mixing a chitin raw material and a solvent; A spinning step of spinning the spinning solution through centrifugal spinning; A self-assembly step in which the evaporation of the solvent occurs in the spinning step and the chitin is self-assembled; And a forming step of forming a hierarchical structure while passing through the self-assembling step.

In order to accomplish the object, the solvent includes 1,1,1,2,2,2-hexafluoro-2-propanol (HFIP), methanol, ethanol, 1,4-dioxane, dichloromethane (DCM), N, (DMF), dimethylsulfoxide (DMSO), acetic acid, HCl, and trifluoroacetic acid (TFA). Wherein the spinning step comprises: storing the spinning stock solution; A spinning nozzle for discharging the spinning stock solution contained in the reservoir; And a series of rod collectors surrounding the reservoir. The concentration of the spinning liquid in the manufacturing step is 0.4 w / v% or more to 0.8 w / v% or less, and the spinning speed of the spinning nozzle in the spinning step is 3000 rpm to 5000 rpm.

The chitin fiber having the hierarchical structure according to the present invention has excellent mechanical properties. The centrifugal spinning process for producing chitin fibers simplifies the process and allows a large amount of fibers to be produced at a low cost, and allows the chitin nanofibers constituting chitin fibers to self-assemble to form a hierarchical structure.

Fig. 1 (a) is a photograph showing the Lewis structure of? -Chitin, Fig. 1 (b) is a photograph of HFIP solvent to make a spinning solution, (E) is a SEM (Scanning Electron Microscope) photograph of chitin fiber, (f) is an AFM (Atomic Force Microscope) of chitin fiber, It is a photograph.
2 (a) to 2 (f) are SEM photographs of chitin fibers obtained by varying the parameters, and FIGS. 2 (g) to 2 (i) are graphs of diameters of chitin fibers obtained by varying the parameters.
3 is an AFM photograph showing a hierarchical structure of chitin fibers.
4 is a POM (Polarized Optical Microscope) photograph showing birefringence of chitin fiber.
FIG. 5 (a) is an X-ray diffraction (XRD) pattern of chitin fibers, and FIG. 5 (c) is a GIWAXS (Grazing Incidence Wide Angle X -ray Scattering, Scratch angle wide angle X-ray scattering) pattern image.
6 is a photograph showing the ability of the chitin fibers to absorb electrolytes (a) to (c).

Hereinafter, a chitin fiber having a hierarchical structure according to the present invention and a method of producing the same will be described in detail with reference to examples and drawings.

Hierarchical structure is a structure that can be found in bones, muscles, etc., and is a fiber-specific structure that is collectively aligned along the fiber's radiation axis. Natural materials are often formed in a hierarchical structure to optimize mechanical properties . A material having a hierarchical structure has a low density and a high strength. However, artificial fibers have not been able to imitate this hierarchical structure so far.

Thus, in the present invention, a chitin fiber having a hierarchical structure was prepared through a centrifugal spinning step and a self-assembly step. The following chitin fibers are assumed to be aggregates of chitin nanofibers. The chitin fibers preferably have a diameter distribution of not less than 500 nm and not more than 10 mu m. When the diameter of the chitin fiber is 500 nm or less, it is difficult to sufficiently exhibit its function as a fiber. When the chitin fiber has a diameter of 10 탆 or more, the surface area thereof is not sufficiently wide and there is a limitation in exhibiting properties such as hygroscopicity.

The chitin nanofibers described below are included in the chitin fibers in a hierarchical structure. The diameter of the chitin nanofiber is preferably from 3 nm or more to 50 nm or less. When the diameter of the chitin nanofiber is 3 nm or less, the nanofiber may be deformed in the process of canceling the capillary stress described below. When the chitin nanofiber has a diameter of 50 nm or more, Do.

Wherein the centrifugal spinning process comprises: preparing a spinning solution by mixing chitin and a solvent; Spinning the spinning liquid through a centrifugal spinning process; Evaporating the solvent in the spinning step and self-assembling the chitin; And forming a hierarchical structure through the self-assembly step.

The spinning solution may be obtained by mixing chitin and a solvent. The solvent is 1,1,1,2,2,2-hexafluoro-2-propanol (HFIP), methanol, ethanol, 1,4-dioxane, dichloromethane ), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), Acetic acid, HCl, Trifluoroacetic acid (TFA)

HFIP is a fluorinated solvent. HFIP can dissolve hydrogen bonds between acetylamino side chain groups of chitin polymers. Due to the nature of HFIP, which is highly volatile due to its low boiling point and high vapor pressure, It is possible to easily induce the self-assembly of chitin nanofibers by reactivating the inter-hydrogen bonds.

Fig. 1 (a) shows the Lewis structure of the? -Chitin chain. In the case of the chitin molecules constituting the α-chitin chain, the unpaired electron pairs of the oxygen atoms in the ring are not unevenly distributed to the side chains through the anomeric effect. On the other hand, in the case of the β-chitin chain, the unpaired electron pairs of the oxygen atoms in the ring can be shared by the σ ^* _CO- bond of the side chain through the Anomeric Effect. Therefore, the hemiacetal group of the β-chitin chain can be decomposed more easily than the α-chitin chain due to the anomeric effect.

Fig. 1 (b) is a photograph showing an HFIP solvent for preparing a spinning solution solution. Volatile organic solvents such as methanol, ethanol, DCM, aprotic solvents such as DMF, DMSO, and acetic acid, HCl, and TFA can also be used as a single solvent or mixed solvent. HFIP solutions are known to stabilize the thermally unstable β-chitin chain.

The chitin powder is added to a solvent, thoroughly stirred at room temperature, and then mechanically homogenized using a high-speed blender to prepare a spinning solution. As used herein, the term "stirring" includes any form of stirring, and includes stirring, shaking, swirling, sonicating, shearing, etc., But the present invention is not limited thereto.

The centrifugal spinning process is a process similar to the cotton candy manufacturing process in which the spinning stock solution in the reservoir is discharged using a high-speed spinning nozzle and collected by a series of bar size collectors surrounding the spinnerets. Fig. 1 (c) is a schematic view of a centrifugal spinning process for making chitin fibers.

The shape and diameter of the chitin nanofibers can be controlled by controlling various conditions such as the concentration of the spinning solution, the rotation speed of the nozzle, the diameter of the nozzle, and the distance between the nozzle and the collector. The details of this will be described with reference to examples.

The present invention is characterized in that self-assembled chitin nanofibers can be produced through a single process without collecting the spinning solution with a high-pressure collector and introducing any additional process such as a coagulation step.

Fig. 1 (d) is a digital photograph of as-spun chitin fiber obtained by the centrifugal spinning process and reminiscent of cotton candy. FIG. 1 (e) is a SEM (Scanning Electron Microscope) image of the chitin fiber, and it can be seen that it has a fiber shape randomly entangled. FIG. 1 (f) is an AFM (Atomic Force Microscope) photograph of chitin fibers showing a hierarchical structure collectively aligned along the spin axis. 3 is another AFM photograph showing the hierarchical structure of chitin fibers.

FIG. 4 is a POM (Polarized Optical Microscope) image showing birefringence of chitin fibers. The birefringence refers to a phenomenon in which the refractive index is different even when the wavelength of light incident in an optically anisotropic medium is the same. This phenomenon occurs only when the structure of the medium is anisotropic. Observation of this birefringence proves that the chitin fibers form a hierarchical structure.

In nature, chitin exists as semi-crystalline and exists in two main distinct polymorphic forms, a-chitin (orthorhombic) and beta-chitin (monoclinic). Since these chitin crystals have other molecular forms that can be intuitively distinguished through Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis (Fig. 1 (a) shows the structure of? ) Indicate different characteristic peaks.

As can be seen from the FT-IR spectrum of chitin fiber of Figure 5 (a), β-chitin has a single broad absorption peak at about 1630 cm ^-1 due to intramolecular C═O ... HO hydrogen bonding. On the other hand, α-chitin is characterized by isolated peaks at 1620 cm ^-1 and 1660 cm ^-1 , indicating that the intramolecular C═O ··· HO hydrogen bonds are simultaneously coordinated with the C═O ··· HO hydrogen bonds between the layers It arises from a parallel arrangement of molecules. In particular, the chitin fibers obtained by the above production method exhibit absorption spectrum peaks located between the two polymorphs. This result shows that both chitin nanofibers constituting the chitin fibers contain both? -Chine and? -Chitin, and the crystallographic characteristics of the two chitin chains coexist.

The XRD (X-ray diffraction) pattern of FIG. 5 (b) also shows a similar tendency. a peak corresponding to the crystallographic reflection between chitin nanofibers (2? = 9.06 占) layer appears between? -chin (2? = 9.34) and? -chin (2? = 8.24).

Further, the GIWAXS (Grazing Incidence Wide Angle X-ray Scattering) pattern of FIG. 5 (c) shows that two strong arcuate points appear at qz values of 1.37 and 0.60 Å ^-1 . This gives more detailed information about the structure as well as the orientation of the chitin fibers. In other words, it means that the supramolecular chitin nanofibers are arranged in a hierarchical structure along the spin axis of the chitin fiber. Here supramolecule means that individual molecules are aggregated close to a specific crystal phase by hydrogen bonding.

Hereinafter, the present invention will be described in detail by way of examples.

Example 1

Chitin powder (extracted according to a conventional protocol using squid) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Halocarbon) solvent were used. The chitin / HFIP solution for the CJS process was homogenized using a high-speed blender (IKA, IKA ULTRA-TURRAX® T 25 digital) while stirring at room temperature and spun at 10,000 rpm for 5 minutes. The radioactive solution was put into a reservoir of a centrifugal spinning device and spinned to prepare chitin fiber. The concentration of the spinning solution was set to 0.6 w / v%, and the rotation speed of the nozzle was set to 5000 rpm.

Example 2

The chitin fibers were collected from a barrel collector and pressed with ICP (isostatic cold pressure, ILSHIN Autoclave, ISA-WIP-45-75-150-AL) at 200 MPa to produce chitin fiber circular mat.

Comparative Example 1

The chitin fiber was prepared in the same manner as in Example 1, except that the concentration of the spinning solution was set to 0.4 w / v% and the rotation speed of the nozzle was set to 5000 rpm. In other words, chitin powder (extracted according to a conventional protocol using squid) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Halocarbon) solvent were used. The chitin / HFIP solution for the CJS process was homogenized using a high-speed blender (IKA, IKA ULTRA-TURRAX® T 25 digital) while stirring at room temperature and spun at 10,000 rpm for 5 minutes. The radioactive solution was put into a reservoir of a centrifugal spinning device and spinned to prepare chitin fiber. The concentration of the spinning solution was set to 0.4 w / v%, and the rotation speed of the nozzle was set to 5000 rpm.

Comparative Example 2

The chitin fiber was prepared in the same manner as in Example 1 except that the concentration of the spinning solution was set to 0.8 w / v% and the rotation speed of the nozzle was set to 5000 rpm. In other words, chitin powder (extracted according to a conventional protocol using squid) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Halocarbon) solvent were used. The chitin / HFIP solution for the CJS process was homogenized using a high-speed blender (IKA, IKA ULTRA-TURRAX® T 25 digital) while stirring at room temperature and spun at 10,000 rpm for 5 minutes. The radioactive solution was put into a reservoir of a centrifugal spinning device and spinned to prepare chitin fiber. The concentration of the spinning solution was set to 0.8 w / v%, and the rotation speed of the nozzle was set to 5000 rpm.

Comparative Example 3

The chitin fiber was prepared in the same manner as in Example 1, except that the concentration of the spinning solution was set to 0.6 w / v%, and the rotation speed of the nozzle was set to 3000 rpm. In other words, chitin powder (extracted according to a conventional protocol using squid) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Halocarbon) solvent were used. The chitin / HFIP solution for the CJS process was homogenized using a high-speed blender (IKA, IKA ULTRA-TURRAX® T 25 digital) while stirring at room temperature and spun at 10,000 rpm for 5 minutes. The radioactive solution was put into a reservoir of a centrifugal spinning device and spinned to prepare chitin fiber. The concentration of the spinning solution was set to 0.6 w / v%, and the rotation speed of the nozzle was set to 3000 rpm.

Comparative Example 4

The chitin fiber was prepared in the same manner as in Example 1, except that the concentration of the spinning solution was set to 0.6 w / v% and the rotation speed of the nozzle was set to 4000 rpm. In other words, chitin powder (extracted according to a conventional protocol using squid) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Halocarbon) solvent were used. The chitin / HFIP solution for the CJS process was homogenized using a high-speed blender (IKA, IKA ULTRA-TURRAX® T 25 digital) while stirring at room temperature and spun at 10,000 rpm for 5 minutes. The radioactive solution was put into a reservoir of a centrifugal spinning device and spinned to prepare chitin fiber. The concentration of the spinning solution was set to 0.6 w / v%, and the rotation speed of the nozzle was set to 4000 rpm.

Comparative Example 5

A circular mat was prepared in the same manner as in Example 2, except that the chitin fibers were replaced with a polyolefin (Celgard (R) 2400). In other words, the fibers were collected in a bar size collector and pressed with ICP (isostatic cold pressure, ILSHIN Autoclave, ISA-WIP-45-75-150-AL) at 200 MPa to produce circular mats.

Comparative Example 6

A circular mat was prepared in the same manner as in Example 2, except that the chitin fibers were replaced with glass fibers (Glass Fiber, GF, Whatman). In other words, the fibers were collected in a bar size collector and pressed with ICP (isostatic cold pressure, ILSHIN Autoclave, ISA-WIP-45-75-150-AL) at 200 MPa to produce circular mats

Observation of the shape of chitin fiber according to the concentration of the spinning liquid and the rotation speed of the nozzle

The surface of the chitin fibers was recorded at an acceleration voltage of 3 kV using a scanning electron microscope (SEM, Hitach High-Technologies, S-4800).

As can be seen from Figs. 2 (a) to 2 (c), when the concentration of the spinning stock solution is 0.4 w / v% and 0.8 w / v%, respectively, / v% were uniform and smooth.

As can be seen from Figs. 2 (d) to 2 (f), when the rotational speed of the nozzle is 3000 rpm and the rotational speed of the nozzle is 4000 rpm, as compared with the irregular ribbon, appear.

Diameter of chitin fiber according to concentration of spinning liquid and rotation speed of nozzle

As can be seen from FIGS. 3 (g) to 3 (i), when the rotation speed of the nozzle was 4000 rpm and 5000 rpm, the normal distribution was shown and the average diameter was 2 μm except for the case where the rotation speed of the nozzle was 3000 rpm And a chitin fiber having a diameter distribution of 500 nm or more and 10 μm or less was found when the rotation speed of the nozzle was 3000 rpm and 5000 rpm, respectively, except for 4000 rpm.

Evaluation of Electrolyte Absorption Capacity According to the Components of the Spinning Solution

Electrolyte wetting test was performed using 1M bis (trifluoromethane) sulphonamide lithium salt (LiTFSI) electrolyte dissolved in dimethoxyethane (DME).

As can be seen from Figs. 6 (a) to 6 (c), the chitin fiber mat has a time (time difference) as compared with Celgerd (Fig. 6 (a), Comparative Example 5), GF mat As a result, the electrolyte absorption performance was excellent in both the vertical and horizontal directions.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It can be understood that it is possible.

Claims (9)

In the chitin fibers,
Wherein the chitin nanofibers have a diameter of 3 nm or more and 50 nm or less and a diameter distribution of the chitin fibers is 500 nm or more, Lt; RTI ID = 0.0 > 10 < / RTI > delete delete A nonwoven mat made using the chitin fibers of claim 1. A manufacturing step of mixing a raw material of chitin and a solvent to prepare a spinning solution;
A spinning step of spinning the spinning solution through a centrifugal spinning process;
A self-assembly step in which the evaporation of the solvent occurs in the spinning step and the chitin molecules are self-assembled; And
The method of claim 1, wherein the forming of the chitin fiber comprises forming a layered structure through the self-assembly step. 6. The method of claim 5,
The solvent may be selected from the group consisting of 1,1,1,2,2,2-hexafluoro-2-propanol (HFIP), methanol, ethanol, 1,4-dioxane, dichloromethane (DCM), N, N-dimethylformamide DMSO), Acetic acid, HCl, Trifluoroacetic acid (TFA).
6. The method of claim 5,
Wherein the step of radiating comprises:
A reservoir containing the stock solution;
A spinning nozzle for discharging the spinning solution contained in the storage; And
And a centrifugal spinning device comprising a series of bar size collectors surrounding the reservoir.
8. The method of claim 7,
Wherein the concentration of the spinning stock solution is 0.4 w / v% or more to 0.8 w / v% or less in the production step,
Wherein the spinning speed of the spinning nozzle in the spinning step is 3000 rpm or more to 5,000 rpm or less. A membrane made using the chitin fibers of claim 1.

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