KR101284246B1 - A Method for Preparing Sea-Island-Type Fiber by High-Speed Melt Spinning, Sea-Island-Type Fiber Prepared Thereby, A Method for Preparing Nano-Fiber, Nano-Fiber Prepared Thereby and Composite Comprising the Nano-Fiber - Google Patents

Abstract

The present invention relates to a composite material comprising an island-in-the-sea fiber by ultra-fast melt spinning, a island-in-the-sea fiber, a nanofiber manufacturing method, and a nanofiber and nanofiber produced accordingly. Melting the island component polymer and the sea component polymer separately; And a rate at which the molten island component polymer and the molten sea component polymer are more than a rate at which the molten island component polymer and the molten sea component polymer begin to induce elongation-induced crystallization behavior through a island-in-the-sea composite spinning nozzle, and a rate at which properties decrease. An island-in-the-sea fiber manufacturing method comprising the step of spinning at an ultra-fast spinning speed and in the island-in-the-sea fiber so that the weight ratio of island-to-sea polymer to sea-based polymer is 5:95 to 95: 5; There is provided a method for producing nanofibers to be removed by sea component from islands-in-sea fibers, and nanofibers prepared according to the present invention, and composites including the nanofibers. The polymer-nanofiber composite including nanofibers having an average fiber diameter of 1 μm and a non-aqueous shrinkage of 2% or less has excellent light transmittance. In addition, since the nanofibers have a low coefficient of thermal expansion (CTE), high orientation, excellent thermal stability, strength, and / or mechanical properties, the fiber components in the polymer-fiber composites used in electrical, electronic, semiconductor, optical, and display materials. Suitable for use as

Description

Method for preparing island-in-the-sea fiber by ultra-fast melt spinning, method for preparing island-in-the-sea fiber, nano-fiber manufacturing method, nano-fiber prepared according to the present invention and composite comprising the nano-fiber {A Method for Preparing Sea-Island-Type Fiber by High-Speed Melt Spinning, Sea-Island-Type Fiber Prepared Thereby, A Method for Preparing Nano-Fiber, Nano-Fiber Prepared Thereby and Composite Comprising the Nano-Fiber}

The present invention relates to a method for producing island-in-the-sea fibers by ultra-fast melt spinning, and a method for producing island-in-the-sea fibers, nanofibers prepared according to the present invention, nanofibers prepared according to the present invention, and composites including the nanofibers.

Polymeric materials are excellent in physical properties such as light weight, moldability, non-destructiveness, design, processability, etc., and are of interest as substitutes for substrate materials such as, for example, glass substrates. Therefore, such a polymer material is required to have a combination of excellent thermal expansion properties, thermal stability (dimension stability), light transmittance, optical properties, surface flatness and chemical resistance, etc. of the glass substrate used in the prior art as a substrate material.

On the other hand, polymer materials are generally processed together with inorganic materials or metal materials during processing to devices used in the fields of electricity, electronics, semiconductors, optics and displays. However, the thermal expansion coefficient of a polymer material, for example, an epoxy resin, is about 50 to 80 ppm / ° C., and the thermal expansion coefficient of a ceramic material and a metal material which are inorganic particles (for example, the thermal expansion coefficient of silicon is 3 to 5 ppm / ° C.). The coefficient of thermal expansion of copper is 17 ppm / ° C.), and the coefficient of thermal expansion (CTE) is very large, several to several tens of times.

Therefore, during the processing, the physical properties and processability of the polymer material are significantly limited due to the different coefficients of thermal expansion of the polymer material and the inorganic material or the metal material. In addition, for example, an undercoat layer, an inorganic barrier layer and an overcoat layer are laminated on both sides of a bare film, which is a case of semiconductor packaging or the like in which a silicon wafer and a polymer substrate are used adjacently, or a transparent optical film. In the case of a plastic substrate, the thermal expansion coefficient difference between the interlayer materials (polymers and inorganic materials) is large, and thus, the difference in the coefficient of thermal expansion (CTE-mismatch) between the components during the process / use temperature change such as heating / cooling is large. Due to the thermal stress (thermal stress) occurs at the interface, resulting in product defects such as crack generation, interfacial peeling, bending of the substrate, peeling-off of the coating layer, breaking the substrate.

As such, due to the CTE of a very high polymer material compared to the metal / ceramic material, it is difficult to secure the design and processability / reliability of the next-generation parts and substrates requiring high integration, high fineness, flexibility, and high performance. In other words, due to the high thermal expansion properties of the polymer material at the part process temperature, not only defects occur in manufacturing the part, but also the process is limited and the design of the part and securing processability and reliability are problematic. Therefore, improved thermal expansion properties of the polymer material, that is, suppression of dimensional change, are required to secure processability and reliability of electronic components.

Until now, in order to improve the thermal expansion characteristics of polymer materials (i.e., suppress the dimensional change), generally, (1) a method of designing a new polymer resin with reduced CTE by a new polymer synthesis method, or (2) inorganic particles (inorganic fillers) ) And / or composites with fibers / fabrics have been used.

On the other hand, in order to use the polymer composite material as a display material or an optical material, excellent light transmittance and surface planarity are required in view of product characteristics.

However, when the conventional polymer resin and the inorganic particles are complexed, a large amount of inorganic particles must be blended in order to exhibit the desired effect of improving the thermal expansion characteristics, thereby impairing the light transmittance of the composite material required for the optical material. In addition, composites of resins and fibers currently used generally, such as glass fibers and / or fibrous carbon nanotubes (CNTs), also do not ensure light transmittance suitable for use as optical materials.

On the other hand, the light transmittance in the composite system depends on the size, refractive index, filler content, film thickness, wavelength, etc. of the filler (inorganic material, fiber, etc.) in the composite, as shown in Equation 1 below.

[Equation 1]

(Wherein, I .: incident light intensity, I: intensity of transmitted light, n _m: the matrix (in the case of the polymer composite: the refractive index, n _p of the polymer resin) refractive index of the filler, r: a diameter of the filler, χ: thickness of the film , φ: content of additive (filler), λ: wavelength of incident light)

Therefore, in order to secure the light transmittance of the conventional polymer-glass fiber composite, a method of controlling the refractive index difference between the matrix resin and the glass fiber filler to 0.002 or less has been proposed. However, this method is difficult to select a polymer resin having a low refractive index difference of 0.002 level with the glass fiber in the entire visible wavelength range, it is difficult to manufacture a film with excellent optical properties, or to increase the manufacturing cost to maintain light transmittance There is no difficulty. In other words, when using low-cost E-glass type high refractive glass fibers, a resin having a relatively high refractive index should be used for refractive index matching. There is a difficult problem. In addition, when using a glass fiber having a low refractive index in order to solve this problem, there is a problem that the manufacturing cost of the composite film is increased due to the use of expensive glass fibers.

On the other hand, as can be seen in the above Equation 1, by controlling the diameter of the filler small, it is possible to secure the light transmittance in the composite material required for use as an optical material irrespective of the difference in refractive index. Accordingly, nanofibers having a fiber diameter of 1000 nm or less have been of interest in the field of polymer composites.

Nanofibers have been produced by conventional electrospinning methods. It is possible to produce fibers of several tens of nm to several microns in diameter by electrospinning, but it is not only difficult to manufacture filament form due to the process characteristics, but also difficult to control the structure of the fiber, so it can be used as a reinforcing material of composite materials. There is a limit to the production of ultrafine fibers having excellent orientation, high crystallinity and thermal and mechanical properties. In addition, since the nanofibers produced by electrospinning are difficult to manufacture in the form of filaments, these nanofibers are mostly manufactured in the form of nonwoven fabrics. Furthermore, the electrospinning method is not only low productivity, but also difficult to control the quality of the electrospinning method, there is a concern that the environmental problem occurs due to the solvent during the production and use of nanofibers.

Also known are methods of producing nanofibers in the form of islands-in-the-sea fibers after slow spinning. However, nanofibers produced by low-speed spinning and stretching have low crystallinity and insufficient thermal stability due to the high orientation of these parts, and thus are not suitable for use in composites for electronic materials. That is, the composite material for an electronic material including nanofibers prepared by low-speed spinning and stretching has a problem in that quality is degraded due to deformation and shrinkage caused by heat during processing.

In addition, the conventional polymer-fiber composite, as shown in Figure 1, due to the shape and / or woven form of the fiber surface unevenness in the final composite and there is a problem of poor surface planarity.

Therefore, it can be used as a next-generation semiconductor substrate, printed circuit board (PCB), packaging, organic thin film transistor (OTFT), flexible display substrate, etc. for electrical, electronic, semiconductor, optical and display materials. There is a need for polymeric composites having suitable high orientation, good crystallinity, improved thermal shrinkage (thermal expansion properties), good thermal stability, mechanical properties, and / or light transmission, and nanofibers suitable for use in such polymeric composites and methods of making the same. .

According to one aspect of the present invention, there is provided a method for producing island-in-the-sea fibers having a low coefficient of thermal expansion (CTE), improved thermal shrinkage, excellent thermal stability, crystallinity, strength and / or mechanical properties, regardless of the type of polymer.

According to another aspect of the present invention, an island-in-water type containing nanofibers having a low coefficient of thermal expansion (CTE), improved thermal shrinkage, excellent thermal stability, excellent thermal stability, crystallinity, strength, and / or mechanical properties Fiber is provided.

According to another aspect of the present invention, there is provided a method for producing nanofibers having a low coefficient of thermal expansion (CTE), improved thermal shrinkage, excellent thermal stability, crystallinity, strength and / or mechanical properties regardless of the type of polymer. .

Furthermore, according to another aspect of the present invention, nanofibers having low coefficient of thermal expansion (CTE), improved thermal shrinkage, good thermal stability, crystallinity, strength, and / or mechanical properties are provided.

In addition, according to another aspect of the present invention, polymer-organic nanofiber composites comprising nanofibers having low coefficient of thermal expansion (CTE), improved thermal shrinkage, excellent thermal stability, crystallinity, strength, and / or mechanical properties Is provided.

According to one embodiment of the present invention,

Melting each of the island component polymer and the sea component polymer separately; And

At a rate at which the molten island component polymer and the molten sea component polymer begin to undergo strain-induced crystallization behavior through the island-in-the-sea composite spinning nozzle; There is provided an island-in-the-sea fiber manufacturing method comprising the step of spinning at an ultra-fast spinning speed at a rate slower than the rate of deterioration of physical properties and in a island-in-sea fiber so that the weight ratio of island-to-sea polymer to sea-based polymer is 5:95 to 95: 5. do.

According to another embodiment of the present invention,

There is provided an island-in-the-sea fiber comprising nanofibers having an average diameter of 1 μm or less and a non-aqueous shrinkage of 2% or less as an island component prepared by the island-in-the-sea fiber method according to the present invention.

According to another aspect of the present invention,

Provided is a method for preparing nanofibers by removing sea components of islands-in-the-sea fibers produced by the method of the present invention.

Furthermore, according to another aspect of the present invention,

Provided are nanofibers having an average diameter of 1 μm or less and a non-aqueous shrinkage of 2% or less produced by the method for producing nanofibers according to the present invention.

According to another embodiment of the invention,

According to the present invention, a polymer-organic nanofiber composite including a nanocomponent nanofiber having an average diameter of 1 μm or less and a non-aqueous shrinkage of 2% or less is provided.

By producing the island-in-the-sea fibers by the ultra-fast melt composite spinning method according to the present invention, island-in-the-sea fibers comprising nanofibers having a uniform nano-diameter as a island component are obtained irrespective of the type of polymer. Further, by removing the sea component of the island-in-the-sea fibers, nanofibers having a uniform nano diameter are obtained.

Nanofibers contained as island components in island-in-the-sea fibers produced by the method of the present invention and nanofibers prepared by the method of the present invention are not only fine in average diameter of less than 1㎛ but also non-aqueous shrinkage of less than 2% Low coefficient of thermal expansion (CTE), improved thermal shrinkage, good thermal stability, crystallinity, strength, and mechanical properties and high orientation.

Therefore, the nanofibers are used for the next-generation semiconductor substrates, printed circuit boards (PCBs), packaging, organic thin film transistors (OTFTs), flexible display substrates, transparent plates, optical lenses, and plastics for liquid crystal display devices. Polymers used in electrical, electronic, semiconductor, optical and display materials such as substrates, substrates for color filters, plastic substrates for organic EL display elements, solar cell substrates, touch panels, light guide plates, optical elements, light guide paths, LED encapsulants, etc.- It is suitable for use as a fiber component with polymeric binders in fiber composites. Furthermore, the island-in-the-sea fibers can themselves be used as polymer-fiber composites. The islands-in-sea fibers and nanofibers may be used in the form of woven or nonwoven fabrics, and may be used in any of a variety of forms that are generally known, such as long fibers and short fibers. Furthermore, composites comprising island component nanofibers according to the present invention also exhibit low thermal expansion coefficient (CTE), improved thermal shrinkage, excellent thermal stability, crystallinity, strength, and mechanical properties. And display materials.

1 is a view showing the surface irregularities of the conventional polymer-fiber composite,
2 is a view showing a melt spinning process by the method of the present invention,
3 is a view showing the shape of a nozzle used for producing the polymer nanofiber according to the present invention,
4 is a view showing a cross section of an island-in-the-sea fiber obtained by the method according to the present invention,
5A is a 2D-WAXD pattern of PP fibers obtained by PP single spinning,
Figure 5b is a 2D-WAXD pattern of PET fibers obtained by PET single spinning,
FIG. 5C is a 2D-WAXD pattern of islands-in-the-sea fibers (74 degrees, island diameter of fiber 1 µm) obtained by composite spinning of islands-in-sea fibers (sea component PP, island components PET),
5D is a 2D-WAXD pattern of islands-in-the-sea fibers (3808 degrees, islands fiber diameter 300 nm) obtained by composite spinning of islands-in-sea fibers (sea component PP, island components PET),
6A is a conceptual diagram illustrating the occurrence of surface irregularities in a composite material using a circular cross-sectional island-in-the-sea fiber,
6B is a conceptual diagram illustrating the improvement of surface planarity in a composite material in which island-in-the-sea fibers having a flat cross section according to the present invention are used,
7A is a photograph of a PP-PET islands-in-the-sea fiber obtained in Example 1,
7B is a 2D-WAXD pattern showing a high crystal peak of the PP-PET islands-in-the-sea fibers obtained in Example 1,
8A is a photograph of a PP-PET islands-in-the-sea fiber obtained in Comparative Example 3,
8B is a 2D-WAXD pattern showing a high degree of orientation in the amorphous portion of the PP-PET islands-in-the-sea fiber obtained in Comparative Example 3,
9 is a graph showing the heat shrinkage rate of the island-in-the-sea fibers prepared in Example 1 and Comparative Example 3.

In the island-in-the-sea fiber manufacturing method according to the embodiment of the present invention, first, the island component polymer and the sea component polymer are separately melted, and then the melted island component polymer and the melted sea component polymer are formed through a nozzle for island-in-the-sea composite fiber. Ultrafast spinning in island-in-the-sea form.

Hereinafter, the island-in-the-sea fiber manufacturing method according to the present invention will be described in detail with reference to the drawings.

2 shows a melt spinning process according to the present invention for producing island-in-sea fibers. As shown in Fig. 2, the island component polymer and the sea component polymer are each injected into a separate extruder and melted. Since the melting temperature of each polymer is generally known, one skilled in the art can appropriately select a suitable melting temperature for the polymer used.

Thereafter, as shown in FIG. 3, the molten island component polymer and the molten sea component polymer are each injected into the nozzle for island-in-the-sea composite spun fiber through separate inlets and spun through the nozzle. When spun, the island component polymer is fed into the core stream and the sea component polymer is sheathed into the composite in which the island component and the sea component are spun together. Thus, the island-like fibers shown in FIG. Type Fiber).

On the other hand, the cross-sectional shape of the nozzle discharge port can be deformed into various shapes, so that the island-in-the-sea fiber having any desired various cross-sections can be produced. Although not limited thereto, the cross-sections of islands-in-sea fibers and / or island component fibers may be circular, triangular, right triangle, square, rectangular, polygonal, oval, flat,-, Y, +, #, and * It may have any one release cross section selected from the group consisting of. In the present invention, "flat cross section" means a cross section of any flat shape in which the transverse length of the cross section is larger than the longitudinal length as compared with the conventional circular cross section.

As the spinning method, any method generally known in the art may be used, but is not limited thereto, but partly oriented yarn (POY) spinning and off-line drawing process, spin draw yarn (SDY) Process, HOY (highly oriented yarn) process, etc. are mentioned.

As the island component polymer and the sea component polymer, any kind of thermoplastic polymer generally known to be used for preparing island-in-the-sea fibers may be used. Thus, although not particularly limited, the island component polymer and the sea component polymer may be, for example, polyethylene terephthalate (PET), a soluble PET copolymer, a poly ester (PE), a soluble PE copolymer, nylon, polyethylene naphthalate (PEN), At least one type independently selected from the group consisting of polypropylene (PP), polyethersulfone (PES), polyvinylidene fluoride (PVDF), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), aromatic polyester and liquid crystalline polymer Can be used.

As the island component polymer and the sea component polymer, thermoplastic polymers having different compatibility are selected. For example, polymers having different hydrophilicity and hydrophobicity, polymers having different melting points, or polymers having different solubility in a solvent may be selected as a composite polymer and a sea component polymer, respectively. The choice of such island and sea component polymers is generally known in the art and may be appropriately selected as needed.

On the other hand, the spinning of the molten island component polymer and the sea component polymer is performed at an ultra-high speed above the spinning speed at which the molten island component polymer and the molten sea component polymer begin to cause strain-induced crystallization behavior. On the other hand, when spinning at extreme speeds, the difference in cooling speed between the inside and outside of the fiber is increased to form a non-uniform cross section, which causes a sudden drop in physical properties or draw resonance (cyclic fluctuations in cyclic cross-section, pulsation). Due to the incidence of radiation). Therefore, the ultra-fast spinning is spinning at a slower spinning speed than the rate at which physical property degradation occurs. As used herein, the "rate at which property deterioration occurs" means a slower rate of physical property deterioration or trimming rate caused by the non-uniform cross section formation. The "rate causing the induced crystallization behavior" and the "rate at which property degradation occurs" depends on the combination of the polymer of the island component and the sea component used, but the composite spinning of the non-aqueous shrinkage of the island component fiber obtained is approximately 2% or less. And the composite spinning can be performed at a spinning speed of approximately 3km / min to 8km / min so that the average diameter is 1㎛ or less.

The strain-induced crystallization behavior of the polymer refers to the phenomenon that crystallization occurs due to high strain stress when the molten polymer solidifies, and when the fiber is spun, the strain stress is increased above the critical point by speeding up the spinning speed. In addition, the crystallization can occur in addition to solidification.

In general, in fiber spinning, elongation-induced crystallization of fibers occurs with neck-like deformation, similar to necking, where stress is concentrated and high strain rates occur. The fiber having the fiber structure formed by the elongation-induced crystallization has a crystal structure with high crystallinity and orientation, unlike conventional low-speed spinning, stretching, and heat-treated general fibers, and at the same time, relatively small amorphous regions having low orientation. This results in good mechanical properties and relatively low thermal deformation.

In particular, when high-speed spinning by simultaneously complexing two or more polymers in an island-in-water type, the spinning speed at which elongation-induced crystallization occurs increases or decreases depending on the combination of polymers. The crystallinity and thermal strain of the components also change.

Therefore, the thermal and / or mechanical properties of the same polymer can be improved through the composite melt spinning such as island-in-the-sea and sheath-core. It is necessary to select the spinning speed.

Specifically, but not limited to this, for example, in the case of single spinning, PP (polypropylene) can be spun at a speed of up to 5 km / min causing elongation-induced crystallization at a speed of 2 km / min. And in the case of single spinning, PET (polyethylene terephthalate) can elongate at a speed of up to 6 km / min causing elongation-induced crystallization at a speed of 4 km / min. However, in the case of complex spinning using PP as sea component and PET as island component, elongation-induced crystallization occurs at a speed of 3 km / min, regardless of the number of island components of island-in-the-sea fibers at a high speed of up to 7 km / min. It can radiate. PP single spinning (FIG. 5A), PET single spinning (FIG. 5B), and composite spinning (FIG. 5C: 74 degrees, fiber diameter of 1 μm and 5D: 3808) of islands-in-sea fibers (sea component PP, island component PET) The 2D-WAXD pattern of islands-in-the-sea fibers obtained with a drawing component fiber diameter of about 200 nm) is shown in FIGS. 5A to 5D.

In addition, as can be seen in Figure 5b, in the case of PET alone spinning elongation-induced crystallization occurs from 4 km / min, as shown in Figures 5c and 5d, in the composite spinning of island-in-the-sea fibers containing PET as a island component Elongation-induced crystallization occurs rapidly from 3 km / min and shows relatively high crystallinity, orientation, and mechanical properties at final speed, and the island component nanofibers of the island-in-the-sea fibers thus formed exhibit improved non-aqueous shrinkage (reduced non-aqueous shrinkage). .

In addition, 3808 degrees of PET as a coating component and nanofibers as 74 degrees of PET have a higher degree of crystallinity (45%) and crystal orientation, and a non-thermal shrinkage ratio of 10% or more compared to nanofibers as a coating component. 1.7%), physical property improvement of 20% or more (strength 500 MPa, modulus of elasticity 1.5 GPa).

Thus, by using a specific combination of island-based polymers and sea-based polymers for the complex spinning of islands-in-the-sea fibers, spinning at a specific high-speed spinning rate at which elongation-induced crystallization occurs, the average diameter is less than 1 µm and the average specific shrinkage is less than 2%. Component nanofibers are obtained.

For example, but not limited to: ① island-in-sea fiber using PEN as island-based polymer and PET as sea-component polymer, ② islands-in-sea fiber using PET as island-based polymer and nylon as sea-component polymer, ③ conductive Islands-in-sea fibers using PET as powder polymer and usable PET copolymer as sea component polymer, ④ PEN as island component polymer, islands-in-sea fiber using nylon as sea component polymer, ⑤ PEN as island component polymer and sea component polymer Island-in-the-sea fiber using a usable PET copolymer as ⑥, island-in-the-sea fiber using PET as island-based polymer and PP as the sea-component polymer, and island-in-the-sea fiber using PEN as island-based polymer and PP as the sea-based polymer. At least one type of island-in-the-sea fiber selected from the group consisting of 3 km / min and 7 km / min Can be. Preferably, the composite spinning of island-in-the-sea fibers using PET as the island component polymer and PP as the sea component polymer may be performed at 4 km / min to 7 km / min.

At the time of spinning, the weight ratio of the island component polymer to the sea component polymer may be 5:95 to 95: 5. This is because uniform nanofibers with an average diameter of 1 µm or less are obtained without fusion between island component fibers in the above mixing ratio range.

Furthermore, it is possible to carry out complex spinning at a frequency of 30 or more, more preferably 1,000 or more, and most preferably 2,000 or more so that the non-aqueous shrinkage of the island component fiber is 2% or less and the average diameter is 1 μm or less. On the other hand, when the degree is less than 30, even if the number of island components is small, even if the island-in-the-sea yarn is narrowed in the range capable of spinning, it is difficult to obtain a island component fiber of 1 μm or less, and the island-in-the-sea yarn having a large number of island components that can be obtained is advantageous for nanofiber production.

Therefore, the larger the number, the better and the upper limit is not particularly limited.

The composite spinning is performed at a temperature in the range of about 20 ° C. to 50 ° C. higher than the melting point of the polymer having a high melting point among the island-based polymer and the sea component polymer used. For example, in the case of the composite spinning of sea component PP / island component PET may be specifically spinning in a temperature range of 270 ℃ to 300 ℃.

In particular, in the case where the islands-in-the-sea fibers have a flat cross section, the composite comprising the island component nanofibers of such islands-in-the-sea fibers exhibits an improved flatness as shown in FIG. 6B.

Ultra-fast spinning islands-in-the-sea fibers that cause elongation-induced crystallization as described above have a neck-like deformation due to the high draft (a ratio of winding speed / nozzle discharge rate) due to ultra-fast spinning. At the same time, the crystallized part due to elongation-induced crystallization has a high degree of crystallinity and orientation, and the amorphous part has a low degree of orientation, and contains a diagram component having excellent thermal stability, low coefficient of thermal expansion (CTE), strength, and mechanical properties, which are less morphologically modified by heat. It is made of islands-in-sea fibers and therefore does not require a separate drawing process.

In addition, by removing the sea component from the island-in-the-sea fibers obtained by the island-in-the-sea fiber manufacturing method according to the present invention, the island-in-the-sea component among the island-in-the-sea fibers can obtain nanofibers.

The sea component can be removed by any method known in the art and can be removed using, for example, but not limited to, a solvent which dissolves only the sea component. As the solvent, any kind generally known in the art may be used, and may be appropriately selected depending on the type of the selected polymer and the sea component polymer.

By removing the sea component from the island-in-the-sea fibers, polymer nanofibers having an average diameter of 1 µm or less, preferably 500 nm or less, more preferably 300 nm or less and a specific water shrinkage of 2% or less are obtained. Polymer nanofibers produced by the method of the present invention have a CTE (Coefficient of Thermal Expansion) of 50 ppm / ° C. or less. Furthermore, among the island-in-the-sea type fibers manufactured by the method according to the present invention, the polymer nanofibers, which are the intermediate components, also have a coefficient of variation (CV) of 10% or less, strength of 200 MPa or more, strength variation of 10% or less (CV). ), Less than 100% elongation, less than 10% elongation variation (CV), more than 500 MPa initial modulus, and / or less than 10% initial modulus variation (CV) characteristics.

Accordingly, the polymer nanofibers produced by the method according to the present invention have low thermal expansion coefficient (CTE), excellent thermal stability, thermal contraction rate, orientation, strength, light transmittance and mechanical properties as well as electrical, electronic, semiconductor, It is suitable for use as a fiber component in polymer-fiber composites used as optical and display materials. The nanofibers may be used in the form of woven fabrics, knitted fabrics, nonwoven fabrics, unidirection multilayers, short cuts, and the like, in the polymer-fiber composite.

Furthermore, the island-in-the-sea fiber produced by the method according to the present invention containing the nanofibers as the island component may be used as a polymer-fiber composite by processing the island-in-the-sea fiber itself without removing the sea component. Specifically, when the melting point of the sea component is lower than the island component, only the sea component is melted in the island-in-the-sea fibers, so that the sea component is the polymer matrix in the polymer-fiber composite and the island component is the fiber component which is the fiber reinforcement material. It can be made of polymer-fiber composites used for semiconductor, optical and display materials. In this case, the island-in-the-sea fibers are directionally arranged in UD (unidirection) or woven form, or randomly arranged in the form of short-fiber nonwoven fabric or spun-bond nonwoven fabric, and the polymer is formed through high-temperature high pressure press or molding. Can be manufactured from fiber composites

According to another embodiment of the present invention, there is also provided a polymer-organic nanofiber composite including the island component nanofibers. As described above, the island component nanofibers are used as the fiber component in the polymer-organic nanofiber composite. As the polymer resin binder, any curable polymer resin binder conventionally known to be used in organic-inorganic composites for electric, electronic, semiconductor, optical and / or display materials may be used, and the polymer resin binder is not particularly limited. Specifically, as the polymer resin binder, a photocurable polymer resin binder or a thermosetting polymer resin binder may be used.

Photocurable polymeric resin binders are generally photocurable oligomers, photocurable monomers, photoinitiators and any additives added as needed (e.g. inhibitors, bleing agents, antifoams, stabilizers, antioxidants, ultraviolet absorbers, adhesion promoters, Pigments, inorganic fillers, and the like). The polymer-organic nanofiber composite according to the present invention may be used a photocurable polymer resin binder including any kind of photocurable oligomer, photocurable monomer, photoinitiator and any other additives known in the art.

Examples of the photocurable oligomers that can be used in the photocurable polymer resin binder include, but are not limited to, epoxy acrylates, urethane acrylates, polyester acrylates, acrylic acrylates, polybutadiene acrylates, silicone acrylics. Elates, melamine acrylates, dendritic acrylates, cycloaliphatic epoxy (hydrogenated epoxy), aromatic epoxys (specifically bisphenol A epoxy, bisphenol F epoxy), aliphatic cyclic epoxy Aliphatic cyclic epoxy (specifically dicyclo pentadiene type epoxy) and oxetane are mentioned. These may be used alone or in combination of two or more.

Examples of the photocurable monomer that can be used in the photocurable polymer binder include, but are not limited to, (meth) acrylate monomers having mono-, di-, tri- or higher functionality. More specifically, the (meth) acrylate monomers have one or more acrylate groups, or methacrylate groups, but are not limited to, for example, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxy Tetraethylene glycol acrylate, phenoxy hexaethylene glycol acrylate, isobornyl acrylate, isobornyl methacrylate, bisphenol ethoxylate diacrylate, ethoxylate phenol monoacrylate, polyethylene glycol 200 diacrylate, tripropylene Glycol diacrylate, trimethyl propane triacrylate, polyethylene glycol diacrylate, ethylene oxide addition type triethyl propane triacrylate, pentaerythritol tetraacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacryl Late, ethoxyl ET may be a de pentaerythritol tetra acrylate, 2-phenoxyethyl acrylate, bisphenol A diacrylate federated ethoxylates. These may be used alone or in admixture of two or more.

As radical photopolymerization initiator for acrylates, any radical photopolymerization initiator known in the art can be used, but is not limited to 2,4-bistrichloromethyl-6-p-methoxysteel-s-triazine , 2-p-methoxysteel-4,6-bistrichloromethyl-s-triazine, 2,4-trichloromethyl-6-triazine, 2,4-trichloromethyl-4-methylnaphthyl- 6-triazine, benzophenone, p- (diethylamino) benzophenone, 2,2-dichloro-4-phenoxyacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone , 2-hydroxy-2-methylproriophenone, pt-butyltrichloroacetophenone, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) phenyl phosph Pin oxide, 2-methyl thioxanthone, 2-isobutyl thioxanthone, 2-dodecyl thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, and 2,2'- Bis-2-chlorophenyl And -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole compounds.

In addition, any cationic photopolymerization initiator known in the art may be used as the cationic photopolymerization initiator for epoxy resins, but is not limited thereto, iodonium salts, borate salts, triazine compounds, azo compounds, peroxides, sulfonium salts, azo Nium salt, halonium salt, more specifically diphenyl-4-thiophenoxyphenylsulfonium hexafluoroantimonate, tri-p-trisulfonium trifluoromethanesulfonate, tri-p-trisulfonium hexafluorophosphate , Triphenylsulfonium tetrafluoroborate, 4-isopropyl-4'-methyldiphenyl iodonium tetrakis (pentafluorophenyl) borate, bis (4-t-butylphenyl) iodium trifluoromethanesulfonate, bis ( 4-t-butylphenyl) iodine hexafluorophosphate, diphenyliodine hexafluorobisic acid, diphenyliodine hexafluorophosphate, diphenyliodnium triflu Ormethanesulfonic acid, benzoin, benzyl, benzoin methyl ether, benzoin isopropyl ether, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl Phenylketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinolpropane-1-one, N, N-dimethylaminoacetophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2 -tert-butyl anthraquinone, 1-chloroanthraquinone, 2-amyl anthraquinone, 2-isopropyl thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, 2,4- Examples include diisopropyl thioxanthone, acetophenone dimethyl ketal, benzophenone, 4-methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, and the like. have.

The photopolymerization initiator may be blended in an amount of 1 to 10 parts by weight per 100 parts by weight of the mixture of the photocurable oligomer and the photocurable monomer. If the amount of the initiator is less than 1 part by weight, the curing does not proceed properly or the curing rate is too slow. If the amount is more than 10 parts by weight, the curing degree is too high, the brittleness is high, or after the reaction is present as a non-reactant, there is a problem of lowering the physical properties.

Thermosetting polymeric binders are generally thermosetting resins, curing agents, optional catalysts and optional additives added as needed (e.g., inhibitors, bleing agents, antifoams, stabilizers, adhesion promoters, antioxidants, ultraviolet absorbers, pigments, inorganics). Fillers and the like). In the polymer-organic nanofiber composite according to the present invention, a thermosetting polymer binder including any kind of thermosetting resin, a curing agent, an optional catalyst, any other additives, and the like known in the art may be used.

As the thermosetting resin, any kind of thermosetting resin generally known in the art may be used, but is not limited thereto. For example,

Epoxy resins, phenol resins, polyimide resins, polyester resins, allyl ester resins, bismaleimide resins, isocyanate resins, polyphenylene ether resins, acrylic resins, melamine resins, silicone resins, benzoxadine resins, urea resins, Phenol resins, alkyd resins, furan resins, polyurethane resins, and aniline resins. These may be used independently or may use 2 or more types together.

Although it does not limit by this, For example, cresol novolak-type epoxy resin, bisphenol-A epoxy resin, bisphenol F-type epoxy resin, phenol novolak-type epoxy resin, alkylphenol novolak-type epoxy resin, biphenol F type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, epoxide of condensate of phenols and aromatic aldehydes having phenolic hydroxyl groups, triglycidyl isocyanurate, alicyclic epoxy resins, copolymers thereof And the like can be used. These may be used alone or in combination of two or more.

The curing agent may also be used any kind of curing agent generally known in the art, and may be used, but not limited to, an amine curing agent, a phenol curing agent, an anhydride curing agent and the like. More specifically, as the amine curing agent, aliphatic amines, cycloaliphatic amines, aromatic amines, other amines and modified polyamines may be used, and amine compounds including two or more primary amine groups may be used. Specific examples of the amine curing agent include 4,4'-dimethylaniline (diamino diphenyl metone) (4,4'-Dimethylaniline (diamino diphenyl methone, DAM or DDM), diamino diphenyl sulfone (DDS) , at least one aromatic amine selected from the group consisting of m-phenylene diamine, diethylene triamine (DETA), diethylene tetraamine, triethylenetetraamine (triethylene tetramine, TETA), m-xylene diamine (MXDA), methane diamine (MDA), N, N'-diethylenediamine (N, N'- DEDA), tetraethylenepentaamine (TEPA), and at least one aliphatic amine selected from the group consisting of hexamethylenediamine, isophorone diamine (IPDI), N-aminoethyl pyrazine ( N-aminoethyl piperazine, AEP), Bis (4-A One or more alicyclic amines selected from the group consisting of no 3-methylcyclohexyl) methane (Bis (4-amino 3-methylcyclohexyl) methane, Larominc 260), other amines such as dicyandiamide (DICY), and polyamides And modified amines such as epoxides.

Examples of the phenol-based curing agent include, but are not limited to, phenol novolac, o-cresol novolac, phenol p- xylene resin, phenol 4,4'-dimethylbiphenylene resin, phenol dicyclopentadiene resin, and the like. Can be.

Examples of the anhydride-based curing agent include, but are not limited to, aliphatic anhydrides such as dodecenyl succinic anhydride (DDSA), poly azelaic poly anhydride, hexahydrophthalic Hexahydrophthalic anhydride, Cycloaliphatic anhydrides such as HHPA), methyl tetrahydrophthalic anhydride (MeTHPA), methylnadic anhydride (MNA), trimellitic anhydride (TMA), Aromatic anhydrides such as pyromellitic acid dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), tetrabromophthalic anhydride (TBPA), chlorendic acid And halogen-based anhydrides such as chlorendic anhydride (HET).

Catalysts may also be used, but are not limited to any type of curing agent generally known in the art, for example, dimethyl benzyl arnine (BDMA), 2,4,6-tris Tertiary amines such as (dimethylaminomethyl) phenol (2,4,6-tris (dimethylaminomethyl) phenol, DMP-30), 2-methylimidazole (2MZ), 2-ethyl-4-methyl-imidazole ( 2E4M), imidazoles such as 2-heptadecylimidazole (2HDI), and Lewis acids such as BF3-monoethyl amine (BF3-MEA) and the like.

In the thermosetting resin binder, the thermosetting resin and the curing agent are cured by the reaction of the reactive functional group of the thermosetting resin and the reactive functional group of the curing agent. Therefore, those skilled in the art can suitably adjust the content of the curing agent in the thermosetting resin binder according to the type of thermosetting resin and the curing agent used.

As the curable resin binder in the polymer-organic nanofiber composite according to the present invention, any photocurable resin binder and thermosetting resin binder generally known in the art may be used as described above. The compounding ratio of the photocurable resin binder and the thermosetting resin binder component and the molecular weight (weight average molecular weight and / or number average molecular weight) of the resin and the like are generally known in the art, and the present invention is not limited thereto. Those skilled in the art can easily make this choice.

As shown in FIG. 6A, the polymer-organic nanofiber composite including the island component fiber of the island-in-the-sea fiber having a general circular cross section as a fiber component exhibits severe irregularities on the surface of the composite due to the cross-sectional shape of the island-in-the-sea fiber. Therefore, the surface flatness of the composite surface is inferior. On the other hand, by dissolving the sea component of the island-in-the-sea fiber having a flat cross section and using the island component fiber having a flat cross section, as shown in FIG. 6B, the unevenness of the surface of the composite material is improved, thus providing excellent surface flatness. Indicates. Thus, by using the island-in-the-sea fiber having a flat cross section as a reinforcing material in the composite material, as shown in FIG. 6B, the island component fibers are arranged at a uniform height and spacing as compared to the conventional circular cross-sectional island-in-the-sea fiber and ultimately the final polymer. The surface irregularities of the organic nanofiber composites are minimized and exhibit excellent surface planarity.

In the polymer-organic nanofiber composite, the amount of the polymer resin binder and the organic nanofibers may be 10/90 to 90/10 weight ratio, preferably 30/70 to 70/30 weight ratio. If the amount of the polymer resin is less than 10 parts by weight based on 90 parts by weight of organic nanofibers, the amount of the polymer resin binder is small and the fibers are not effectively bound, so it is difficult to produce a composite material, and the amount of the polymer resin binder is 10 parts by weight of the organic nanofibers. If it exceeds 90 parts by weight, the fiber content is low, and the CTE reduction effect is not sufficient.

The polymer-organic nanofiber composite may be prepared by any method of preparing a composite including a polymer resin and a fiber known in the art, and the method of preparing the composite is not particularly limited. For example, when the organic nanofibers are in the form of woven fibers such as long fibers, webs, nonwoven fabrics, woven fabrics and knitted fabrics, or unidirection multilayer forms including a plurality of layers arranged in one direction, the fibers of this type may be It can be prepared into a composite by impregnation with a binder. When the organic nanofibers are in the form of short fibers, the short fibers may be dispersed in a resin binder (binder solution) to prepare a composite.

As used herein, the term "polymer-organic nanofiber composite" refers to not only a polymer resin and an organic nanofiber, but also a component constituting the polymer resin binder according to the type of the polymer resin binder according to the curing type (a photocurable resin binder Occasions: photocurable monomers, photoinitiators and optional additives; for thermosetting resin binders: used in a broad sense, including both before and / or after curing reactions including thermosetting agents, optional curing catalysts and optional additives) do. The polymer-organic nanofiber polymer composite according to the present invention may be in the form of a cured composite film (sheet).

The curing reaction of the polymer-organic nanofiber composite according to the present invention may be used any reaction conditions generally known. The curing reaction conditions may vary depending on the type of polymer resin and the curing agent used, and those skilled in the art may appropriately select the curing reaction conditions according to the components of the curable polymer composite.

Although not limited by this, For example, when photocuring, the hardened | cured composite material can be obtained by making it harden | cure for 1 to 10 minutes at the light quantity of 80-200 W / cm. In addition, for example, in the case of thermal curing, the cured composite can be obtained by curing at 150 to 200 ° C. for about 1 hour or more.

According to another aspect of the present invention, there is also provided a composite film formed of the polymer-organic nanofiber composite, wherein the light-transmissive composite film can be prepared by curing the polymer-organic nanofiber composite according to the present invention.

The polymer-organic nanofiber composite according to the present invention has excellent thermal expansion properties, specifically 20 ppm / ° C. or less, preferably 15 ppm / ° C. or less, and excellent light transmittance between 50 to 90%.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to illustrate the present invention, which does not limit the present invention.

Example 1: Preparation of island-in-the-sea polymer fibers by ultra-fast spinning

As shown in Fig. 2, the PET resin and the seaweed PP resin were separately melted in two extruders. Thereafter, the molten island component and the molten sea component polymer were weighed in a 2: 3 weight ratio by a gear pump and supplied to the island-in-the-sea fiber nozzle as shown in FIG. The island component polymer and the sea component polymer are discharged from the nozzle at a spinning temperature of 280 ° C. to have 74 islands of water in one island of the island-in-the-sea fiber (about 20 μm in diameter), and spin at 7 km / min to have an average diameter of about 1 An island-in-the-sea fiber having a island-like fiber having a 탆 thickness, an average non-shrinkage ratio of 2%, a strength of 250 MPa, and a modulus of 1.1 GPa was obtained.

Example 2: Preparation of island-in-the-sea nanofibers by ultra-fast spinning

As shown in Fig. 2, the PET resin and the sea component PP resin were melted separately in two extruders. Thereafter, the molten island component and the molten sea component polymer were weighed to a 2: 3 weight ratio by a gear pump and supplied to the island-in-the-sea fiber nozzle as shown in FIG. The island component polymer and the sea component polymer are discharged from the nozzle at a spinning temperature of 280 ° C. to have 3808 island components in one island of island-in-sea fibers (about 25 μm in diameter), and are spun at 7 km / min to have an average diameter of about An island-in-the-sea fiber having a island-like fiber having a thickness of 300 nm, an average specific shrinkage of 1.7%, a strength of 400 MPa, and a modulus of 1.5 GPa was obtained.

Comparative Example 1 PP Fiber Production by Ultra-High Speed Single Spinning of PP Polymer

After the PP polymer was melted using only one of the two extruders shown in FIG. 2, the melted PP polymer was fed to a 36-hole single spinning nozzle using a gear pump. PP fibers discharged from the nozzle at a spinning temperature of 280 ° C. and spun at 1 to 5 km / min to obtain diameters of about 12 to 30 μm.

Comparative Example 2: PET Fiber Production by Ultra-High Speed Single Spinning of PET Polymer

After the PET polymer was melted using only one of the two extruders shown in Fig. 2, the melted PET polymer was fed to a 36-hole single spinning nozzle by a gear pump. It was discharged from the nozzle at the spinning temperature of 280 ℃ and spun at 1 ~ 6 km / min to obtain a PET fiber having a diameter of about 10 ~ 30 ㎛.

.

Comparative Example 3: Preparation of island-in-the-sea polymer nanofibers by spinning and stretching

As shown in Fig. 2, the PET resin, which is a component, and the PP resin, which is a sea component, were melted in two extruders. Thereafter, the island component and the sea component polymer melted with a gear pump were weighed in a 2: 3 weight ratio and supplied to the island-in-the-sea fiber nozzle as shown in FIG. The island component polymer and the sea component polymer are discharged at 500 m / min from the nozzle and the sea component polymer at 280 ° C. so that the number of island components is 74 in one island of island-in-the-sea fibers (about 20 μm). Wound up. Thereafter, stretching was performed 2.5 times with an off-line drawing machine to obtain an island-in-the-sea fiber having an average diameter of 1 µm, an average specific shrinkage ratio of 9%, a strength of 350 MPa, and a modulus of 1.5 GPa.

(Property evaluation)

A photo of the islands-in-the-sea fibers produced in Example 1 is shown in FIG. 7A and a 2D-WAXD pattern showing high crystal peaks and good orientation is shown in FIG. 7B. In addition, the photo of the PP-PET islands-in-the-sea fiber prepared in Comparative Example 3 is shown in Figure 8a and 2D-WAXD pattern showing a high degree of orientation of the amorphous portion is shown in Figure 8b.

The thermal deformation characteristics of each island-in-the-sea fiber obtained in Example 1 and Comparative Example 3 were evaluated at a temperature rising rate of 2 ° C./min at a temperature range of room temperature to 250 ° C. using a thermal mechanical analyzer (TMA). 9 is shown. As shown in FIG. 9, the island-in-the-sea fiber (D series) prepared by the low-speed spinning and off-line stretching of Comparative Example 3 showed a shrinkage of 10 to 20%, but the island-in-the-sea type manufactured by the ultra-fast spinning of Example 1 Fiber (S5) exhibited a relatively very low heat shrinkage of 3% or less.

On the other hand, PP single spinning (comparative example 1, FIG. 5A), PET single spinning (comparative example 2, FIG. 5B), PP (sea) / PET (degrees) island-in-the-sea yarn (74 degrees, average component fiber 1 micrometer, FIG. 5c) (Example 1), PP (sea) / PET (degrees) island-in-the-sea yarn (3808 degrees, average fiber diameter of about 300 nm) (Example 2, Figure 5d) as a result of high-speed spinning 2D- As can be seen from the WAXD pattern, the maximum radiation rate that can be radiated can be up to 5 km / min for PP alone and 6 km / min for PET alone, but it is 74 degrees and 3808 degrees for PP (sea) / PET (degrees) islands. All improved as much as 7 km / min.

On the other hand, when the single component PET is spun alone, elongation-induced crystallization occurs from 4 km / min. However, when PET is an island-in-the-sea island type, it is rapidly occurring from 3 km / min. As it showed high characteristics, it was possible to obtain the effect of improving the structure growth and physical properties than the single spinning. Especially, in case of PET nanofiber of 3808 ° C, crystallinity (45%) and crystal orientation, more than 10% of non-aqueous heat shrinkage, further decrease (non-aqueous shrinkage rate of 1.7%) and 20% or more of physical properties than PET in 74 ° C. Improvement (intensity 400 MPa, modulus of 1.5 GPa).

Example 3 Preparation of Composites Containing Organic Nanofibers

An island-in-the-sea fiber was prepared in the same manner as in Example 2, except that a water-soluble polymer (PP) copolymer made by HUVIS was used as the sea component polymer. Then, at 90 ° C., 48% owf (on the weight, that is, the weight of the additive (NaOH) to the fiber weight, for example, NaOH 48 g if the fabric (fiber) weight is 100 g) The islands-in-sea fibers were immersed for 6 hours to remove sea components and to obtain island component nanofibers.

The island component fibers were then made into a nonwoven fabric (50 mm × 50 mm × 90 μm) and impregnated into the photocurable resin binder. The PET nonwoven fabric impregnated with the resin binder is sandwiched between glass having a spacer of 100 mu m. The upper slide was gently pressed to remove bubbles, and then reacted at 80 W / cm for 3 minutes in a photocuring machine, and then the glass was removed to obtain a light-transmissive composite film.

The photocurable resin binder is 5 wt% photoinitiator (Irgacure 184), 15 wt% trimethylolpropane triacrylate, 4 wt% phenol (EO) 2 acrylate, 16 wt% lauryl acrylate, bisphenol-A epoxy diacrylate oligomer 30 wt% of aliphatic urethane diacrylate oligomer was prepared by combining. In the content ratio of the polymeric resin binder and the textile fabric, the resin binder content was 50wt%, the light transmittance of the light-transmissive composite film was 82%, and the CTE was 15 ppm / ° C.

Example 4 Preparation of Composite Using Sea Island Fiber

The island-in-the-sea fibers prepared in Example 2 were wound in a square frame of 100 × 100 mm at regular intervals in parallel in one direction to prepare a UD-shaped fabric. It is put in a vacuum hot press and pressurized for 10 minutes under vacuum at a load of 10 tons at a temperature of 210 ° C. higher than the melting point of the PP resin and lower than that of the PET resin, followed by quenching to melt only the PP of the sea component. Phosphorus 300 nm nanofibers were prepared with a highly transmissive polymer nanofiber composite having a shape in the UD direction. The prepared composites exhibited physical properties of 70 ppm / ° C., UD direction strength and modulus of 420 MPa and 1.5 GPa, respectively.

Claims (13)

Melting each of polyethylene terephthalate (PET) as an island component polymer and polypropylene (PP) as a sea component polymer; And
The molten island component polymer and the molten sea component polymer were subjected to an island-in-the-sea composite spinning nozzle at a 3 km / min to 7 km / min ultrafast spinning speed and a weight ratio of island-to-sea polymer to sea-based polymer in the island-in-the-sea fiber at 5:95 Iso island-like fiber manufacturing method comprising the step of spinning to 95: 5.
The method of claim 1, wherein the spinning is carried out at a frequency of 30 or more.
delete delete delete A island-in-the-sea fiber comprising island component nanofibers having an average diameter of 1 μm or less and a specific water shrinkage of 2% or less, prepared by the method of claim 1.
The island-in-the-sea fiber of claim 6, wherein the nanofiber satisfies at least one of a modulus of 500 MPa or more and a strength of 200 MPa or more.
The islands-in-the-sea fiber of claim 6, wherein the island-in-the-sea fiber is used as a polymer-fiber composite.
A method for producing nanofibers for removing sea component of islands-in-the-sea fibers produced by the method of claim 1.
A nanofiber having an average diameter of 1 μm or less and a non-aqueous shrinkage of 2% or less prepared by the method of claim 9.
The nanofiber of claim 10, wherein the nanofiber satisfies at least one of a modulus of 500 MPa or more and a strength of 200 MPa or more.
The nanofiber of claim 10, wherein the nanofiber is used as a fiber component in a polymer-fiber composite.
A polymer-organic nanofiber composite comprising the nanofiber of claim 10.

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