Fiber composite structure and manufacturing method thereof

Abstract

A fiber composite structure according to the concept of the present invention comprises a plurality of twisted fiber bundles, each of which comprises a plurality of fiber strands, an adhesive coated on the fiber strands, and functional particles interposed between the fiber strands. The functional particles comprise a material different from the fiber strands. The adhesive comprises polydopamine.

Description

Technology Field

[0001] The present invention relates to a fiber composite structure and a method for manufacturing the same. Background Technology

[0002] Fiber composite structures offer advantages such as reduced weight, increased strength, and improved processability compared to general fibers. Currently, the most widely used fiber composite is Fiber Reinforced Plastic (FRP), which utilizes a method of enhancing strength by arranging fibers within a polymer matrix. These fiber composite structures can be fabricated using a single type of fiber or a combination of multiple fibers. Research is underway to improve the physical and chemical properties of fiber composite structures. Prior art literature

[0003] 1. The Chemistry behind Catechol-Based AdhesionJ. Saiz-Poseu, J. Mancebo-Aracil, F. Nador, F. Busque, and D. Ruiz-Molina, Angew. Chem. Int. Ed.2019,58,696-714, https: / / onlinelibrary.wiley.com / doi / 10.1002 / anie.2018010632. Mussel-inspired surface chemistry for multifunctional coatings H Lee, SM Dellatore, WM Miller, PB Messersmith, SCIENCE, 2007, 318, pp. 426-430, DOI: 10.1126 / science.1147241 The problem to be solved

[0004] The problem that the present invention aims to solve is to provide a structure and a method for manufacturing a fiber composite structure with excellent strength and hydrophilicity. means of solving the problem

[0005] A fiber composite structure according to one embodiment of the present invention comprises a plurality of fiber bundles, each of which comprises a plurality of fiber strands, an adhesive coated on the fiber strands, and functional particles interposed between the fiber strands, wherein the functional particles comprise a material different from the fiber strands, and the adhesive comprises polydopamine.

[0006] According to some embodiments, the fiber strands may include natural fibers or synthetic fibers.

[0007] According to some embodiments, the natural fiber may include at least one of ramie fiber, linen fiber, cotton fiber, jute fiber, wool fiber, silk fiber, and fur fiber.

[0009] According to some embodiments, the artificial fiber may include at least one of polyethylene terephthalate (PET), polypropylene, polyester, nylon, Kevlar and acrylic fibers, metal fibers, glass fibers, and carbon fibers.

[0010] According to some embodiments, the functional particles may include at least one of nanomaterials such as cellulose, graphene, carbon nanotubes, carbon black, and particulate materials with a size of 1 to 100 micrometers, such as black rayon particles.

[0011] According to some embodiments, the first aspect ratio of each of the fiber strands may be greater than the second aspect ratio of the functional particle.

[0012] According to some embodiments, the first aspect ratio may be 1 to 1000, and the second aspect ratio may be 1 to 10.

[0013] According to some embodiments, the spacing between adjacent fiber strands forms a pore, and the size of the pore may be 10 nm to 100 μm.

[0014] A fiber composite structure according to another embodiment of the present invention comprises a plurality of collected or twisted fiber bundles, each of which comprises a plurality of fiber strands, and an adhesive coated on the fiber strands, wherein the adhesive comprises protruding first nano-protrusions and the adhesive comprises polydopamine.

[0015] A method for manufacturing a fiber composite structure according to one embodiment of the present invention comprises preparing a plurality of fiber bundles, soaking the fiber bundles in a solution containing an adhesive material, and drying the fiber bundles soaked in the solution in the air immediately after removing them from the solution.

[0016] According to some embodiments, soaking the fiber bundles in the solution can be done within 1 minute.

[0017] According to some embodiments, drying the fiber bundles can be carried out within one hour.

[0018] According to some embodiments, the solution further comprises functional particles, and the functional particles may include at least one of nanomaterials such as cellulose, graphene, carbon nanotubes, carbon black, and particulate materials with a size of 1 to 100 micrometers such as black rayon particles.

[0019] According to some embodiments, plasma treatment on the surface of the fiber bundles may be further included before soaking the fiber bundles in the solution.

[0020] According to some embodiments, the adhesive material may include catechol-based materials such as dopamine, polydopamine, pyrogallol, alpha-methyldopamine, norepinephrine, dihydroxyphenylalanine, alpha-methyldopa, droxidopa, 5-hydroxydopamine, deacetylated chitosan catechol, hyaluronic acid catechol, and alginate catechol, or one of chitosan, poly(allylamine), poly(L-lysine), and poly(ethyleneimine). Effects of the invention

[0021] A fiber composite structure according to the concept of the present invention comprises twisted fiber bundles, each of which comprises a plurality of fiber strands, and said fiber bundles and said fiber strands can be bonded to each other by a polydopamine adhesive. The polydopamine adhesive can strongly bond said fiber bundles and said fiber strands while causing them to twist during the curing process. As a result, the strength of the fiber composite structure can be increased. According to some embodiments, the polydopamine adhesive may include nano-protrusions on its surface. As a result, the fiber composite structure may have superhydrophilicity. Brief explanation of the drawing

[0022] FIG. 1 is a schematic diagram showing a fiber composite structure according to some embodiments of the present invention. Figure 2 is an enlarged view of aa in Figure 1. Figures 3a, 3b, and 3c are conceptual diagrams illustrating the manufacturing process of a fiber composite structure. Figures 4a, 4b, and 4c are conceptual diagrams illustrating the manufacturing process of a fiber composite structure. FIG. 5 is a conceptual diagram showing the manufacturing process of a fiber composite structure according to some embodiments. Figure 6 is a stress-strain diagram of Example 1, Comparative Example 1, and Comparative Example 2. Figure 7 is a graph showing the change in water contact angle over time for Example 3 and Comparative Example 2. Figure 8 is a graph showing the change in water contact angle according to the number of washes in Examples 3 and 4. Specific details for implementing the invention

[0023] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. In the attached drawings, the components are depicted enlarged from their actual size for convenience of explanation, and the proportions of each component may be exaggerated or reduced.

[0024] Unless otherwise defined, the terms used in the embodiments of the present invention may be interpreted in the sense commonly known to those skilled in the art. Hereinafter, the present invention will be described in detail by explaining exemplary embodiments of the present invention with reference to the attached drawings.

[0026] FIG. 1 is a schematic diagram illustrating a fiber composite structure according to some embodiments of the present invention. FIG. 2 is an enlarged view of aa in FIG. 1.

[0027] Referring to FIG. 1, the fiber composite structure (1000) may include a plurality of fiber bundles (100). The fiber bundles (100) may simply be gathered or twisted. The fiber bundles (100) may be entangled with each other.

[0028] As shown in FIGS. 1 and 2, each of the fiber bundles (100) may include fiber strands (110) arranged adjacent to each other and a polydopamine adhesive (300) coated on each of the fiber strands (110).

[0029] The fiber strands (110) may include natural fibers and synthetic fibers. Natural fibers may include at least one of plant-based fibers such as ramie fiber, linen fiber, cotton fiber, and jute fiber. Animal-based fibers may include wool fiber, silk fiber, and wool (animal hair) fiber.

[0030] Artificial fibers may include at least one of regenerated fibers such as rayon and lyocell fibers, or synthetic fibers such as polyethylene terephthalate (PET), polypropylene, polyester, nylon, Kevlar, and acrylic fibers. They may also include at least one of inorganic fibers such as metal fibers, glass fibers, and carbon fibers. The fiber strands (110) may be composed of only one type of fiber or may be composed of other types of fibers.

[0031] The space between adjacent fiber strands (110) may form a pore (OP). For example, the size of the pore (OP) may be 10 nm to 100 μm.

[0032] The polydopamine adhesive (300) may contain polydopamine. The polydopamine may be formed from dopamine, which is a biomaterial. The polydopamine adhesive (300) may cause fiber strands (110) to bond or fix to each other and fiber bundles (100) to bond or fix to each other.

[0033] The above adhesive may include molecules that combine with oxygen to become polymerized and increase adhesion on any surface, such as hydrophilic, hydrophobic, organic, and inorganic surfaces, and may include catechol-based and amine-based molecules. Catechol-based molecules may be dopamine, polydopamine, pyrogallol, alpha-methyldopamine, norepinephrine, dihydroxyphenylalanine, alpha-methyldopa, droxidopa, 5-hydroxydopamine, deacetylated chitosan-catechol, hyaluronic acid-catechol, and alginate-catechol, and may include one of amine-based molecules such as chitosan, poly(allylamine), poly(L-lysine), and poly(ethyleneimine).

[0034] Functional particles (400) may be interposed between fiber strands (110) and / or fiber bundles (100). The functional particles (400) may include materials different from the fiber strands (110). The functional particles (400) may include at least one, for example, cellulose, graphene, carbon nanotubes, and microparticles of size 1 to 100 micrometers, such as carbon black nanoparticles or black rayon. In this specification, a particle refers to an object having a shape such as a zero-dimensional sphere, a one-dimensional linear shape, and a two-dimensional plane. As an example, the functional particles may be particle fibers such as black rayon.

[0035] Each of the fiber strands (110) may have a first aspect ratio, and the functional particles (400) may have a second aspect ratio. The first aspect ratio may be greater than the second aspect ratio. The first aspect ratio may be 1 to 1000, and the second aspect ratio may be 1 to 10. The length of each of the fiber strands (110) may be greater than the length of each of the functional particles (400).

[0036] FIGS. 3a, 3b, and 3c are conceptual diagrams illustrating the manufacturing process of a fiber composite structure. FIGS. 4a, 4b, and 4c are conceptual diagrams illustrating the formation principle of a fiber composite structure. Specifically, FIGS. 4a, 4b, and 4c are cross-sectional views of fiber strands illustrating the process of fiber strands joining and twisting together.

[0037] Referring to FIG. 3a, a plurality of fiber strands (110) may be provided in a state where they are not joined or fixed to each other. The fiber strands (110) shown in FIG. 3a are designed to have a shape similar to a dandelion seed.

[0038] Referring to FIG. 3b, a dopamine solution (200) may be coated onto a plurality of fiber strands (110). The dopamine solution (200) may contain dopamine. The dopamine solution (200) may further contain Tris buffer, ethanol, sodium (Na), and water. Coating with the dopamine solution (200) may include coating methods such as dip coating and drip coating. Coating with the dopamine solution (200) may be performed within 1 second to 1 minute.

[0039] As shown in FIG. 3b and FIG. 4a, the dopamine solution between adjacent fiber strands (110) can adhere to the surface of the fiber strands (110) by a capillary effect and remain in an aggregated state. According to some embodiments, the dopamine solution (200) may further include functional particles (400).

[0040] For example, as shown in FIG. 4a, the fiber strands (110) may include a first fiber strand (F1), a second fiber strand (F2), a third fiber strand (F3), and a fourth fiber strand (F4) arranged adjacent to each other. A dopamine solution (200) between the first to fourth fiber strands (F1 to F4) may be attached to the first to fourth fiber strands (F1 to F4) by capillary action. Functional particles (400) may be arranged between the first to fourth fiber strands (F1 to F4).

[0041] As shown in FIGS. 3b and 4b, fiber strands (110) coated with a dopamine solution (200) can be naturally dried in an air atmosphere. Oxygen (O2) can be injected through the interface between the air and the dopamine solution (200), and a process of water evaporation can be performed. During the process of water evaporation, the first to fourth fiber strands (F1 to F4) can come closer to each other, and the first to fourth fiber strands (F1 to F4) can receive rotational force. Additionally, the first to fourth fiber strands (F1 to F4) can come closer to the functional particle (400). In this process, the oxygen diffused from the air and the dopamine monomer combine to polymerize, thereby forming polydopamine.

[0042] Referring to FIG. 3c and FIG. 4c, dopamine can be polymerized to form a polydopamine adhesive (300). During the process of water evaporation and the formation of the polydopamine adhesive (300), the first to fourth fiber strands (F1 to F4) may be combined with each other to form a fiber bundle (100).

[0043] FIG. 5 is a conceptual diagram illustrating the manufacturing process of a fiber composite structure according to some embodiments. Except for the items described below, the descriptions overlap with those previously explained through FIG. 3a to 3c and FIG. 4a to 4c, so redundant descriptions will be omitted.

[0044] Referring to FIG. 5, first nano-protrusions (NS1) can be formed by performing plasma treatment on the surface (100S) of a fiber strand (110). The plasma treatment may be, for example, oxygen plasma treatment. Oxygen plasma treatment can be performed by forming a vacuum, injecting oxygen gas, generating plasma, and then reacting the plasma with the surface (110S) of the fiber strand (110). The reaction between the plasma and the surface (110S) of the fiber strand (110) can be performed for more than 1 minute and within 1 hour. Depending on the type of substrate and the plasma treatment conditions, the plasma treatment time may vary. However, plasma treatment must be performed for a certain period of time or longer so that the height of each of the first nano-protrusions (NS1) is formed larger and the aspect ratio of the first nano-protrusions (NS1) increases. For example, the plasma treatment may be performed for approximately 30 minutes. The first nano-protrusions (NS1) may be arranged along a first direction (D1) parallel to the surface (110S) of the fiber strand (110). The first nano-protrusions (NS1) may protrude in a second direction (D2) perpendicular to the surface (110S) of the fiber strand (110). At least some of the first nano-protrusions (NS1) may be bundled together.

[0045] A dopamine solution (200) can be coated onto the surface (110S) of a fiber strand (110) and air-dried naturally. The resulting polydopamine adhesive (300) may include second nano-protrusions (NS2). Each of the second nano-protrusions (NS2) may be formed on a first nano-protrusion (NS1) or on a bundled first nano-protrusion (NS1). The second nano-protrusions (NS2) may overlap with the first nano-protrusions (NS1) in a second direction (D2).

[0047] Example 1

[0048] Untwisted lamination fiber strands that were not bonded to each other with adhesives or the like were prepared. A dopamine solution was prepared by mixing and stirring Tris Buffer, ethanol, dopamine, and NaIO4. The lamination fiber strands were immersed in the dopamine solution for less than 1 minute. Subsequently, the lamination fiber strands were removed from the dopamine solution and dried in the air for less than 1 hour.

[0050] Example 2

[0051] Black Rayon was additionally added to the dopamine solution of Example 1.

[0053] Example 3

[0054] PET fiber strands that were not bonded to each other with adhesives or the like and were not twisted were prepared. Plasma treatment was performed on the PET fibers. Plasma treatment is a process that uses a gas such as oxygen to etch the fiber surface to form a nanostructure and simultaneously impart hydrophilicity. The process was carried out on the fiber strands under a vacuum of 40 mtorr, 40 sccm of oxygen (O2) gas, 50 W of power, and 400 V of voltage. Subsequently, a dopamine solution was prepared by mixing and stirring Tris Buffer, ethanol, dopamine, and NaIO4. The PET fiber strands were immersed in the dopamine solution for less than 1 minute. Then, the PET fiber strands were removed from the dopamine solution and dried in air for less than 1 hour.

[0056] Example 4

[0057] The procedure was carried out in the same manner as Example 3, except that plasma treatment was not performed in Example 3.

[0059] Comparative Example 1

[0060] Untwisted ramie fiber strands that were not bonded to each other with adhesives or the like were prepared.

[0062] Comparative Example 2

[0063] Prepare strands of ramie fiber that are not bonded together with adhesives or the like and are not twisted, and apply forces in opposite directions to one end and the other end of the strands to create a twisted state.

[0065] Comparative Example 3

[0066] In Example 3, the procedure was carried out in the same manner as Example 3, except that the process of coating and drying the dopamine solution was omitted.

[0068] FIG. 6 is a stress-strain diagram of Example 1, Comparative Example 1, and Comparative Example 2. Referring to FIG. 6, it was observed that Example 1 has a stronger strength than Comparative Example 1 and Comparative Example 2.

[0070] Figure 7 is a graph showing the change in water contact angle over time for Example 3 and Comparative Example 2. Referring to Figure 7, it can be seen that the water contact angle of Example 3 is smaller than that of Comparative Example 2. Additionally, as time passes, the water contact angle of Comparative Example 2 increases rapidly, whereas the water contact angle of Example 3 increases only slightly.

[0072] Figure 8 is a graph showing the change in water contact angle according to the number of washes of Example 3 and Example 4. When comparing Example 3 and Example 4, it was observed that Example 3 had a smaller water contact angle than Example 4. In addition, even when the number of washes increased, Example 3 had a smaller water contact angle than Example 4, thereby maintaining durability.

[0074] According to one concept of the present invention, a fiber composite structure comprises twisted fiber bundles, each of which comprises a plurality of fiber strands, and the fiber bundles and the fiber strands can be bonded together by a polydopamine adhesive. As a result, the strength of the fiber composite structure can be increased (see FIG. 6).

[0075] According to another concept of the present invention, the fiber composite structure may include nano-protrusions on the surface of the fiber strands by performing plasma treatment on the fiber strands. By coating a dopamine solution onto the plasma-treated fiber strands and drying them in air, the polydopamine adhesive may also include nano-protrusions. Polydopamine has hydrophilicity (e.g., water contact angle less than 90 degrees) due to its material properties, but the polydopamine adhesive may have superhydrophilicity (e.g., water contact angle less than 10 degrees) by including nano-protrusions. This superhydrophilicity of the polydopamine adhesive can be maintained despite changes in time and environment, compared to when only plasma treatment is performed and polydopamine is not coated (see FIG. 7), or when polydopamine is coated without plasma treatment.

[0076] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

Claim 1 A fiber composite structure comprising a plurality of twisted fiber bundles, each of the fiber bundles comprising a plurality of fiber strands; an adhesive covering the surface of the fiber strands; and a functional particle interposed between the fiber strands, wherein the functional particle comprises a material different from the fiber strands, and the adhesive comprises polydopamine, wherein each of the fiber strands comprises a first nano-protrusion protruding from its surface, and the adhesive comprises a second nano-protrusion continuously formed along the surface of the first nano-protrusion. Claim 2 In claim 1, the fiber strands comprise a fiber composite structure including natural fibers or synthetic fibers. Claim 3 In paragraph 2, the natural fiber comprises at least one of ramie fiber, linen fiber, cotton fiber, jute fiber, wool fiber, silk fiber, and fur fiber. Claim 4 delete Claim 5 In paragraph 2, the artificial fiber is a fiber composite structure comprising at least one of polyethylene terephthalate (PET), polypropylene, polyester, nylon, Kevlar and acrylic fibers, metal fibers, glass fibers, and carbon fibers. Claim 6 In claim 1, the functional particles comprise a particulate material with a size of 1 to 100 micrometers, and the particulate material comprises at least one of cellulose, graphene, carbon nanotubes, carbon black, and black rayon particles, forming a fiber composite structure. Claim 7 A fiber composite structure according to claim 1, wherein the first aspect ratio of each of the fiber strands is greater than the second aspect ratio of the functional particle. Claim 8 A fiber composite structure according to claim 7, wherein the first aspect ratio is 1 to 1000 and the second aspect ratio is 1 to 10. Claim 9 A fiber composite structure according to claim 1, wherein the spacing between adjacent fiber strands forms pores, and the size of the pores is 10 nm to 100 μm. Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete

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