KR20200122751A - Piezoelectric braided knitted fabric and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a piezoelectric braided knitted fabric comprising a plurality of piezoelectric nanofibers and two electrode fibers braided in a braid manner, and a manufacturing method thereof. Moreover, the piezoelectric braided knitted fabric braided in the braid method is a fibrous electrode and a storage device through piezoelectric expression by tension, and can be applied to various fields of application.

Description

Piezoelectric braided knitted fabric and method for manufacturing the same}

The present invention relates to a piezoelectric braid comprising a plurality of piezoelectric nanofibers and two electrode fibers braided in a braid manner, and a method of manufacturing the same. In more detail, it relates to a piezoelectric braid, characterized in that piezoelectric expression through tension.

The piezoelectric effect is an action in which mechanical energy and electrical energy are mutually converted through a piezoelectric material. In other words, when pressure or vibration (mechanical energy) is applied, electricity is generated, and when electricity is passed, vibration is generated.

Piezoelectric material refers to a material that generates electric charge by causing polarization according to mechanical stress.It has a direct effect that generates electric charge under mechanical stress and a reverse piezoelectric effect that causes deformation when an electric field is applied. .

Recently, ubiquitous technologies in which information technology (IT), energy technology (ET), and bio technology (ET) are fused based on nanotechnology are emerging. Along with this, next-generation terminals require convenience of portability, convergence/multifunctionality, and human-friendly type, and are developing into a flexible form. These next-generation terminals must be driven with their own power generation without electrical wire connection.

In the modern society, piezoelectric materials are widely used in acoustic devices such as telephones, medical devices such as ultrasonic blood flow meters, and monitoring devices such as pressure gauges, and have become indispensable materials. Therefore, there is a need to develop a highly efficient piezoelectric material that can be used as a piezoelectric element such as a practical energy harvesting element, an actuator, and a pressure sensor.

In order to realize performance in piezoelectric materials, compression or bending is generally applied, and this is a method to prevent destruction due to permanent deformation of the material. Likewise, in order to express piezoelectricity in a knitted structure, since compression between fibers is very important, piezoelectricity is also expressed through compression or bending in a two-dimensional woven structure, and piezoelectricity due to tension is very limited.

An object of the present invention is to provide a piezoelectric braided product braided in a braid manner.

One object of the present invention is to provide a method of manufacturing the piezoelectric braid.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. There will be.

In order to achieve the above technical problem, an aspect of the present invention provides a piezoelectric braid comprising a plurality of piezoelectric nanofibers and two electrode fibers braided in a braid manner.

According to an embodiment of the present invention, the piezoelectric braid may be piezoelectrically expressed through tension.

According to an embodiment of the present invention, the electrode fibers may not contact each other.

According to an embodiment of the present invention, the piezoelectric nanofiber is barium titanide (BaTiO ₃ ), lead titanide (PbTiO ₃ ), PZT (Pb[Zr _x Ti _x-1 ]O _3, 0<=x <= 1) oxide, age five byumhwa potassium (KNbO _3), oxidation age five byumhwa lithium (LiNbO _3), tantalum oxide Chemistry lithium (LiTaO _3), tungsten sodium (Na ₂ WO ₃ oxide), zinc oxide (Zn ₂ O ₃ ), Ba ₂ NaBb ₅ O ₅ , Pb ₂ KNb ₅ O ₁₅ , NaKNb, bismuth iron oxide (BiFeO ₃ ), sodium niobium oxide (NaNbO ₃ ), Bi ₄ Ti ₃ O ₁₂ , Na _0.5 Bi _0.5 TiO _3, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-trifluoroethylene (P(VDF-FrFE)), and combinations thereof may include any one selected from the group consisting of.

According to an embodiment of the present invention, the electrode fiber is gold, silver, platinum, copper, tin, zinc, palladium, indium tin oxide, copper sulfide, graphite, carbon nanofibers, graphene, graphene oxide, and combinations thereof It may include any one selected from the group consisting of.

According to an embodiment of the present invention, the electrode fiber may be coated with an insulator.

According to an embodiment of the present invention, the end of the electrode fiber may be exposed and connected to a power source.

According to an embodiment of the present invention, the piezoelectric braid may have a tensile strength of 25 MPa to 55 MPa.

According to an embodiment of the present invention, the piezoelectric braid may be used in one or more devices selected from the group consisting of transistors, batteries, energy harvesting devices, sensors, and self-generators.

One aspect of the present invention, the step of providing a plurality of piezoelectric fibers and two electrode fibers; It provides a method of manufacturing a piezoelectric braid comprising; manufacturing the fibers in a braid shape through a braiding process.

According to an embodiment of the present invention, the manufacturing of the braid may be performed so that the electrode fibers do not contact each other.

According to an embodiment of the present invention, in the manufacturing of the braid shape, the size and/or waveform of piezoelectricity may be adjusted by changing the position of the electrode fibers in the braid.

According to an embodiment of the present invention, in the manufacturing of the braid shape, the size and/or waveform of the piezoelectric may be adjusted by changing at least one selected from the group consisting of a braid pattern, an angle, and a fiber thickness.

According to an embodiment of the present invention, after the step of manufacturing the braid shape, the step of securing the electrode by fixing both ends except for the electrode fiber with an insulating material may be further included.

The present invention is excellent in chemical and / or physical durability, particularly the durability against the tension of the knitted fabric, and can be piezoelectrically expressed by tension, through which the compression sensitivity of the existing piezoelectric fabric is out of the limit and It provides a piezoelectric braid capable of generating piezoelectricity.

The piezoelectric braid has the advantage of generating electricity by converting tension into compression by itself without an external device, and at the same time responding to compression to respond to more various deformations and adaptable to various structures.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a photograph of a braid process equipment according to an embodiment of the present invention.
2 is a diagram showing each step of a trace diagram of a braiding process according to an embodiment of the present invention.
3 is an illustration of a trace diagram of a braiding process according to an embodiment of the present invention.
4 is a photograph of a piezoelectric braid structure (electrode fibers are indicated in red) according to a trace diagram of a braiding process according to an embodiment of the present invention.
5 is a photograph of a piezoelectric braid of a 4x4 structure manufactured according to an embodiment of the present invention.
6 is a graph of piezoelectric voltages measured under 5% tensile condition (a) and 10% tensile condition (b) of a piezoelectric braid manufactured according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and therefore is not limited to the embodiments described herein.

Throughout the specification, when a part is said to be "connected (connected, contacted, bonded)" with another part, it is not only "directly connected", but also "indirectly connected" with another member in the middle. "Including the case. In addition, when a part "includes" a certain component, it means that other components may be further provided, rather than excluding other components unless specifically stated to the contrary.

The terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention.

One aspect of the present invention provides a piezoelectric braid comprising a plurality of piezoelectric nanofibers and two electrode fibers braided in a braid manner.

In the present specification, “braided in a braid manner” means that a fabric was fabricated by weaving or braiding fibers, and for the braiding, a braid process equipment, for example, a braid process equipment of FIG. 1 may be used. .

The piezoelectric braid can be piezoelectrically expressed through tension.

In this specification, “tension” means that an external force is applied to an object to cause elongation, and “piezoelectric expression” means that when the piezoelectric body is deformed by applying mechanical deformation from the outside, for example, contraction or tension, etc. The polarization size of the piezoelectric material changes due to the relative positional change and alignment of ions having electrical properties in the piezoelectric material, and due to polarization of the material, the electric charge density at the interface between the electrode and the piezoelectric material changes instantaneously, resulting in movement of electrons. It means that electric energy flows to the outside as is generated.

The piezoelectric material refers to an object having piezoelectricity, and may be, for example, piezoelectric nanofibers.

The piezoelectric nanofibers are barium titanide (BaTiO ₃ ), lead titanide (PbTiO ₃ ), PZT (Pb[Zr _x Ti _x-1 ]O _3, 0<=x<=1), niobium oxide Potassium (KNbO ₃ ), lithium niobium oxide (LiNbO ₃ ), lithium tantalum oxide (LiTaO ₃ ), sodium tungsten oxide (Na ₂ WO ₃ ), zinc oxide (Zn ₂ O ₃ ), Ba ₂ NaBb ₅ O ₅ , Pb ₂ KNb ₅ O ₁₅ , NaKNb, bismuth iron oxide (BiFeO ₃ ), sodium niobium oxide (NaNbO ₃ ), Bi ₄ Ti ₃ O ₁₂ , Na _0.5 Bi _0.5 TiO ₃ , polyvinylidene fluoride (PVDF) ), polyvinylidene fluoride-trifluoroethylene (P(VDF-FrFE)) and combinations thereof, for example, polyvinylidene fluoride-trifluoroethylene (P( VDF-FrFE)).

An electrical conductor is used as the electrode fiber, and the electrical conductor refers to a material that is easy to conduct electricity due to high conductivity. For example, from the group consisting of gold, silver, platinum, copper, tin, zinc, palladium, indium tin oxide, copper sulfide, carbon materials (graphite, carbon nanofibers, graphene, graphene oxide, etc.), and combinations thereof Any one selected, for example, may be copper.

The electrode fibers may not contact each other. Avoid contacting the two electrodes to prevent short circuits.

In order not to contact each other, the electrode fibers may be coated with an insulator. The insulator refers to a material in which no current flows even when an external electric field under normal conditions is applied because there are no freely movable conductive electrons. As the insulator, a polymer insulating material having an insulating property and a flexible property may be used.

The polymer insulating material may include a polyethylene-based polymer, a rubber-based material, an ethylene copolymer, a fluorine-based polymer, a polyvinyl chloride-based polymer, a silicone-based polymer, or a thermoplastic elastomer, but is not limited thereto. As a specific example, the insulator is cross-linking polyethylene (XLPE), natural rubber, ethylene vinyl acetate, polytetrafluoroethylene, 1,3,5-trivinyl-1,3,5 -It may be trimethyl cyclotrisiloxane (1,3,5-trivinyl-1,3,5-trimethyl cyclotrisiloxane), polyvinyl chloride or epoxy resin.

In addition, if the electrode fiber is completely coated with an insulator, since the electrode and the power cannot be connected, the electrode fiber end of the present invention may be exposed and connected to the power source.

The piezoelectric braid may have a tensile strength of 25 MPa to 55 MPa, for example, 35 MPa to 45 MPa.

The tensile strength is a force representing the strength of a material, and refers to a value obtained by dividing the maximum load endured when the material is pulled until it is cut by the cross-sectional area of the material.

The piezoelectric braid may have a tensile modulus of 5% to 20%, for example, 10% to 15%, within a range in which repeated use is possible.

The piezoelectric braid may have a tensile strength of 35 MPa to 45 MPa when 10% to 15% tensile.

In one embodiment of the present invention, the piezoelectric braid may be used for one or more selected from the group consisting of transistors, batteries, energy harvesting devices, sensors, and self-generators.

The piezoelectric braid has a three-dimensional structure, and may be applied to a three-dimensional structure element having one directionality even when tension in the fiber direction is not used. In addition, since it has a structure in which various fibers are in contact, it can be applied to a device using two or more materials or components such as a battery and a transistor. For example, a battery braided fabric having a braid structure may be manufactured by fabricating a negative electrode, a positive electrode, a separator, and an electrolyte from fibers. In addition, for example, the gate, drain, and source electrodes may be made of fibers to produce a braided transistor braid.

The energy harvesting device refers to a device that collects external energy and recycles it into electrical energy. For example, with a piezoelectric energy harvesting device, an element having a piezoelectric effect can be used to create a potential difference through mechanical energy and change, thereby forming a dipole and a compensation charge to generate a current flow.

The energy harvesting device may further include an energy storage device.

The energy storage device may be a component of the energy harvesting device, for example, a capacitor.

Another aspect of the present invention is to provide a plurality of piezoelectric fibers and two electrode fibers; Manufacturing the fibers in a braid shape through a braiding process; It provides a method of manufacturing a piezoelectric braid comprising a.

In the step of providing the plurality of piezoelectric fibers and two electrode fibers, the piezoelectric fibers are barium titanide (BaTiO ₃ ), lead titanate (PbTiO ₃ ), PZT (Pb [Zr _x Ti _x-1 ] O _{3, 0 <= x <=} 1), oxidation age five byumhwa potassium (KNbO _3), oxidation age five byumhwa lithium (LiNbO _3), tantalum oxide Chemistry lithium (LiTaO _3), tungsten sodium (Na ₂ WO ₃ oxide) , Zinc oxide (Zn ₂ O ₃ ), Ba ₂ NaBb ₅ O ₅ , Pb ₂ KNb ₅ O ₁₅ , NaKNb, bismuth iron oxide (BiFeO ₃ ), sodium niobium oxide (NaNbO ₃ ), Bi ₄ Ti ₃ O ₁₂ , Na _0.5 Bi _0.5 TiO ₃ , polyvinylidene fluoride (PVDF), polyvinylidene fluoride-trifluoroethylene (P(VDF-FrFE)), and any one selected from the group consisting of a combination thereof, for example For example, it may include polyvinylidene fluoride-trifluoroethylene (P(VDF-FrFE)). The piezoelectric fiber is a drawing method, a template synthesis method, a supramolecular self-assembly method, and Any one selected from the group consisting of chemical vapor deposition, phase separation, electrospinning, and combinations thereof, for example, may be manufactured through electrospinning, but is limited thereto. It does not become.

For example, the electrospinning method is a method of continuously mass-producing nanofibers having a diameter of several micrometers to tens of nanometers by applying a high voltage to an organic or inorganic solution. In addition, compared to methods such as self-assembly, phase separation, and mold synthesis, there are advantages in that it is simpler, there is no limit to selection of materials, and it is easy to control a high specific surface area, porosity, and structure/size due to the shape.

In general, the electrospinning method can control piezoelectric properties that are highly dependent on the degree of dipole arrangement. Specifically, in the case of having a disordered dipole array structure, since piezoelectric properties do not appear, it is necessary to perform a polarization process of arranging dipoles in the same direction in order to have excellent piezoelectricity. When manufactured through an electrospinning process, Even without performing an additional polarization process, since dipole arrangement occurs simultaneously in the electrospinning process of applying a high voltage between the substrate and the integrated electrode on the nozzle, it is possible to control to have excellent piezoelectricity.

An electrical conductor is used as the electrode fiber, and the electrical conductor refers to a material that is easy to conduct electricity due to high conductivity. The electrical conductor is, for example, from the group consisting of gold, silver, platinum, copper, tin, zinc, palladium, indium tin oxide, copper sulfide, graphite, carbon nanofibers, graphene, graphene oxide, and combinations thereof Any one selected, for example, may be copper.

The electrode fiber may be manufactured by rolling or stretching the electric conductor and then cutting it.

The piezoelectric fiber and electrode fiber may be commercially available products.

The step of fabricating the fibers into a braid shape through a braiding process may be made so that the electrode fibers do not contact each other. Through this, short circuit can be prevented without additional configuration.

In the manufacturing of the braid shape, the size and/or waveform of the piezoelectricity may be adjusted by changing the position of the electrode fibers in the braid.

In the manufacturing of the braid shape, the size and/or waveform of the piezoelectric may be adjusted by changing the braid pattern, angle, fiber thickness, and the like.

Specifically, by modifying the position, braid pattern, angle, and fiber thickness of the electrode fibers, a braided product having different tensile strength and/or tensile modulus can be produced, and the size and/or the size of the piezoelectric electric machine according to the tensile strength and/or the tensile modulus are adjusted. Or you can adjust the waveform.

After the step of fabricating in the form of a braid, the step of securing an electrode by fixing both ends except for the electrode fiber with an insulating material may be further included.

As the insulating material, a polymer insulating material having both insulating properties and flexible properties may be used. The polymer insulating material may include a polyethylene-based polymer, a rubber-based material, an ethylene copolymer, a fluorine-based polymer, a polyvinyl chloride-based polymer, a silicone-based polymer, or a thermoplastic elastomer, but is not limited thereto. As a specific example, the insulator may be crosslinked polyethylene, natural rubber, ethylene vinyl acetate, polytetrafluoroethylene, 1,3,5-trivinyl-1,3,5-trimethyl cyclotrisiloxane, polyvinyl chloride or epoxy resin. have.

In addition, if the piezoelectric braid braid is completely fixed with an insulating material, the electrode and the power cannot be connected, so the electrode fiber end of the present invention can be exposed and connected to the power source.

Hereinafter, preparation examples, examples and experimental examples of the present invention will be described. However, these Preparation Examples, Examples, and Experimental Examples are for describing the configuration and effects of the present invention in more detail, and it should be noted that the scope of the present invention is not limited thereto.

Example

Preparation Example 1. Preparation of piezoelectric nanofibers

P (VDF-TrFE) PIEZOTECH FC25 (MW=450,000 g/mol) purchased from Alkema (France) as a piezoelectric nanomaterial was prepared.

A mixed solution for electrospinning was prepared by dissolving 21% by weight of P(VDF-TrFE) in a mixed solvent in which dimethylformamide (DMF) and acetone were mixed in a volume ratio of 3:2.

6 ml of the mixed solution was placed in a syringe and electrospinned under the following conditions to prepare a piezoelectric nanofiber web: needle type 20 G, flow rate 0.5 ml/h, voltage 15 kV, tip-to-collector distance (tip-to -collector distance, TCD) 15 cm, collector rotation speed 80 RPM

The piezoelectric nanofibers were obtained by fixing the ends of the piezoelectric nanofibers in the piezoelectric nanofiber web prepared in the above process and performing a twisting process: rotation speed 100 RPM, tensile speed 5 mm/s

Example 1. Manufacture of piezoelectric braided product using braid processing equipment

The piezoelectric nanofibers obtained in Preparation Example 1 and electrode fibers (thickness: 300 μm) manufactured using copper were braided using a braiding process equipment (FIG. 1).

The braiding sequence in this embodiment followed the sequence shown in the tracking diagram of FIG.

Specifically, referring to b-1) to b-12) of FIG. 2, the electrode fiber is bonded to the position indicated by the blue dot in FIG. 2a) with respect to the working shelf in the state of b-1), and the manufacturing The piezoelectric nanofibers obtained in Example 1 were combined. When moving from b-1) to b-2), odd horizontal lines move to the right, even horizontal lines move to the left, and when moving from b-2) to b-3), odd vertical lines move upward. And the even-numbered vertical lines moved downward.

The odd, even and vertical lines, and horizontal lines mean that they are shifted away from each other, and it was possible to determine odd, even and vertical lines, and horizontal lines by randomly placing starting points.

Similarly, when moving from b-3) to b-4), it alternately moves to the right and left, and when moving from b-4) to b-5), it alternately moves upward and downward. The staggered movement was continuously repeated and braided into a braid.

At this time, it can be seen that the positions of the electrode fibers indicated by red dots in b-1) to b-12) are different, and that they do not contact each other while braiding is performed.

Examples 2 to 11. Preparation of piezoelectric braids using braid processing equipment

Unlike the position of the blue dot shown in Fig. 2a), a knitted fabric in the same manner as in Example 1, except that the electrode fibers are bonded to the blue dots shown in Figs. 3 a) to j). Was prepared.

The position of the electrode fibers during braiding is marked with a red dot.

As a result of observing the piezoelectric braids manufactured according to a) and b) of FIG. 3, it was confirmed that the piezoelectric braids did not contact each other while the braiding was performed (FIG. 4).

In the piezoelectric braid prepared above, a piezoelectric braid having an electrode connectable to a power source was prepared by covering both ends of the electrode fiber with an insulator (FIG. 5).

Experimental Example 1. Measurement of tensile strength

The tensile strength of the electrospun nanofibers was measured under tensile strength loading conditions using a tensile strength tester (model 4467, Instron Co., USA) according to the ASTM D-638 method. The crosshead speed was 10 mm/s, and at least 20 measurements were performed for each sample to obtain an average value.

As a result of the experiment, it was confirmed that it has a tensile strength of 25 MPa to 35 MPa when tensile at a tensile modulus of 10% to 15%.

Experimental Example 2. Measurement of piezoelectric voltage

The (+) terminal and the (-) terminal of the voltmeter were connected to both electrode fibers of the piezoelectric braided fabric in Example 1.

The braids were stretched by 5% and 10%, respectively, and the numerical values of the voltmeter over time were checked, and the result values are shown in FIG. 6.

As a result of the experiment, it was confirmed that the piezoelectric effect due to tension was expressed.

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims (14)

A piezoelectric braid comprising a plurality of piezoelectric nanofibers and two electrode fibers braided in a braid manner. The method of claim 1,
The piezoelectric braid is a piezoelectric braid, characterized in that the piezoelectric expression through tension. The method of claim 1
Piezoelectric braid, characterized in that the electrode fibers do not contact each other. The method of claim 1,
The piezoelectric nanofibers are barium titanide (BaTiO ₃ ), lead titanide (PbTiO ₃ ), PZT (Pb[Zr _x Ti _x-1 ]O _3, 0<=x<=1), niobium oxide Potassium (KNbO ₃ ), lithium niobium oxide (LiNbO ₃ ), lithium tantalum oxide (LiTaO ₃ ), sodium tungsten oxide (Na ₂ WO ₃ ), zinc oxide (Zn ₂ O ₃ ), Ba ₂ NaBb ₅ O ₅ , Pb ₂ KNb ₅ O ₁₅ , NaKNb, bismuth iron oxide (BiFeO ₃ ), sodium niobium oxide (NaNbO ₃ ), Bi ₄ Ti ₃ O ₁₂ , Na _0.5 Bi _0.5 TiO _3, polyvinylidene fluoride (PVDF ), a piezoelectric braid comprising any one selected from the group consisting of polyvinylidene fluoride-trifluoroethylene (P(VDF-FrFE)), and combinations thereof. The method of claim 1,
The electrode fiber is any one selected from the group consisting of gold, silver, platinum, copper, tin, zinc, palladium, indium tin oxide, copper sulfide, graphite, carbon nanofibers, graphene, graphene oxide, and combinations thereof. Piezoelectric braid containing. The method of claim 1,
Piezoelectric braid, characterized in that the electrode fiber is coated with an insulator. The method of claim 1,
Piezoelectric braid, characterized in that the end of the electrode fiber is exposed and connected to a power source. The method of claim 1,
The piezoelectric braided material has a tensile strength of 25 MPa to 55 MPa. The method of claim 1,
The piezoelectric braid is a piezoelectric braid used for at least one selected from the group consisting of a transistor, a battery, an energy harvesting device, a sensor, and a self-generator. Providing a plurality of piezoelectric fibers and two electrode fibers; And
Manufacturing the fibers in a braid shape through a braiding process;
A method of manufacturing a piezoelectric braid comprising a. The method of claim 10,
The manufacturing method of the piezoelectric braid, characterized in that in the manufacturing of the braid shape, the electrode fibers are manufactured so as not to contact each other. The method of claim 10,
The manufacturing method of a piezoelectric braid includes a feature of adjusting a size and/or a waveform of a piezoelectricity by changing a position of the electrode fibers in the braid. The method of claim 10,
The manufacturing method of the piezoelectric braid includes the feature of adjusting the size and/or waveform of the piezoelectric by changing a braid pattern, an angle, and a fiber thickness. The method of claim 10,
And securing the electrode by fixing both ends of the electrode fiber excluding the electrode fiber with an insulating material after the step of manufacturing the braid shape.

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