Composite fiber

Abstract

Composite fiber which has: a first fiber component element made of a material having a volume resistivity of 5 × 10 -6 up to 5×10 6 Ω·m is formed; and a second fiber component element comprising a ceramic material, wherein the first fiber component element and the second fiber component element are adjacent to each other such that the first and second fiber component elements form a fiber body.

Description

TECHNICAL FIELD

[0001] The present invention relates to a composite fiber. More particularly, the present invention relates to a composite fiber made of at least two fiber component elements. STATE OF THE ART

[0002] Piezoelectric fibers using lead zirconate titanate fiber (hereinafter also referred to as "PZT fiber") are known as vibration sensors and exciters, which can be used for structures such as buildings, automobiles, ships, and aircraft. See, for example, Patent Documents 1 to 6. A smart board is also known in which the PZT fiber is embedded in a structure thereof, allowing the PZT fiber to function as a voltage sensor, vibration sensor, or exciter. See, for example, Patent Document 1. PRIOR ART DOCUMENT PATENT DOCUMENT

[0003] Patent Document 1: Japanese Patent Application No. 2003-12829, Patent Document 2: Japanese Patent Application No. 2005-171752, Patent Document 3: Japanese Patent Application No. 2004-15489, Patent Document 4: Japanese Patent Application No. 2005-59552, Patent Document 5: Japanese Patent Application No. 2005-313715 and Patent Document 6: Japanese Patent Application No. 2010-198092. DESCRIPTION OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] The inventors of the present application have found that there are still problems to be overcome in the conventional lead zirconate titanate (PZT) fiber provided as a ceramic fiber incorporating a ceramic element, and therefore recognized the need to take appropriate measures. Specifically, the inventors of the present application have found the following problems.

[0005] The PZT fiber 100 of Patent Document 1 or the like has a thin PZT layer 102 formed by coating a metal wire 101 (a thin metal wire such as a titanium wire or a platinum wire) with a lead zirconate titanate crystal (a PZT crystal), for example, as shown in Fig. 11A illustrates.

[0006] Such a PZT fiber is produced by growing the PZT crystal on the surface of the metal wire, for example, by a hydrothermal synthesis method. Alternatively, the PZT fiber can also be produced using an extrusion molding method. In the extrusion molding method, which is described in Fig. For example, as illustrated in FIG. 12, a PZT paste 105 (a mixture prepared by combining and kneading a PZT powder, a binder, and water, optionally with an organic solvent and various molding additives) is extruded simultaneously with the metal wire 101 to produce a PZT fiber molded article having a metal core therein, and then the PZT fiber molded article is heated to undergo a debinding process. Subsequently, the PZT fiber molded article is sintered at a higher temperature, whereby a PZT fiber in which a thin PZT layer is provided on the surface of the metal wire can finally be provided.

[0007] Such a conventional PZT fiber is not necessarily sufficient, especially with regard to its strength. In a case where the PZT fiber is used, for example, for a vibration sensor, an exciter, or the like, the PZT fibers 100 must be partially embedded and reinforced in a structure 202 with a stack of CFRP prepregs 201 so that the structure can be used as a smart board 200 (see Fig. 11B and Fig. 11C).

[0008] For example, if the smart board 200 is used as a vibration sensor or exciter, the PZT fiber 100 is a piezoelectric material, so that a potential is generated when the vibration is detected. This allows the smart board to function as a sensor. Conversely, the PZT fiber 100 expands when a potential is applied and contracts or vibrates according to the potential, allowing the smart board to function as an exciter. For example, if the PZT fiber 100 is oriented along an axial direction indicated by an arrow, as shown in Fig. 13A, due to the application of the potential, the PZT fiber can be extended together with the structure 202, as shown in Fig. 13B. Thus, a predetermined PZT fiber among a plurality of PZT fibers 100 in the smart board 200 can function as a sensor and detect the vibration, and another predetermined PZT fiber among them in the smart board 200 can serve as an exciter to control (damp) the vibration. In Fig. 13A and Fig. 13B, a lower portion of each PZT fiber 100 was embedded into the structure 202, in particular into the CFRP prepreg 201 (see Fig. 11C).

[0009] When a ceramic fiber is used as a piezoelectric fiber or the like, strength is required for such a fiber. In this regard, the present inventors found that the strength (e.g., tensile strength or elongation at break) of conventional PZT fibers is about 4 kgf / mm 2, according to the contents of "POLYMERS" July issue (Vol. 57, No. 7, 2008) of The Society of Polymer Science, Japan, and that this strength as a fiber is still insufficient and requires further improvement of the strength of the fiber.

[0010] In view of the above challenge, the present invention was developed. That is, a primary object of the present invention is to provide a fiber that has further increased strength even when serving as a ceramic fiber. SOLUTIONS TO THE PROBLEM

[0011] The inventors of this application attempted to solve the above-described challenge from a new perspective, rather than from a consistent perspective of the conventional art. As a result, the inventors of this application developed a composite fiber capable of achieving the above-described main object.

[0012] The present invention provides a composite fiber including a first fiber component element made of a material having a volume resistivity of 5×10 -6 up to 5×10 6 Ω·m, and includes a second fiber component element including a ceramic material, wherein the first fiber component element and the second fiber component element are adjacent to each other such that the first and second fiber component elements form a fiber body.

[0013] According to another embodiment of the present invention, there is also provided a composite fiber including a first fiber component element including a material of a semiconductor or metalloid and a second fiber component element including a ceramic material, wherein the first fiber component element and the second fiber component element are adjacent to each other such that the first and second fiber component elements form a fiber body. EFFECTS OF THE INVENTION

[0014] The composite fiber according to the present invention may be a fiber having further increased strength even when it serves as a ceramic fiber.

[0015] For example, according to the present invention, the composite fiber is preferably a fiber having higher strength than the conventional PZT fiber.

[0016] It should be noted that the effects described in the present specification are merely examples and are not limited thereto, so that additional effects may be provided. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A to 1C are schematic views schematically illustrating a composite fiber according to an embodiment of the present invention ( Fig. 1A: a perspective view, Fig. 1B: a cross-sectional view, Fig. 1C: a side cross-sectional view). Fig. 2 is a cross-sectional view schematically illustrating a composite fiber according to an embodiment of the present invention, which also illustrates an embodiment wherein a plurality of sub-fiber component elements are provided as the first fiber component element. Fig. 3A and Fig. 3B are schematic views schematically illustrating a composite fiber (core-sheath structure 1) according to an embodiment of the present invention ( Fig. 3A: a partial perspective sectional view, Fig. 3B: a cross-sectional view). Fig. 4A and Fig. 4B are schematic views schematically illustrating a composite fiber (core-sheath structure 2) according to an embodiment of the present invention ( Fig. 4A: a partial perspective sectional view, Fig. 4B: a cross-sectional view). Fig. 5A and Fig. 5B are schematic views schematically illustrating a composite fiber (with multiple cores) according to an embodiment of the present invention ( Fig. 5A: a partial perspective sectional view, Fig. 5B: a cross-sectional view). Fig. 6A and Fig. 6B are schematic views schematically illustrating a composite fiber according to an embodiment of the present invention, in which a first fiber component element is in a fine fiber form ( Fig. 6A: a partial perspective sectional view, Fig. 6B: a cross-sectional view). Fig. 7 is a cross-sectional view schematically illustrating a composite fiber having a biaxial shape according to an embodiment of the present invention. Fig. 8A to 8D are schematic views schematically illustrating a composite fiber according to an embodiment of the present invention ( Fig. 8A: a concentric structure, Fig. 8B: a partial sectional structure of an outer section, Fig. 8C: a half-half cut structure of an outer section, Fig. 8D: a structure of an additional intermediate layer). Fig. 9 is a perspective view schematically illustrating a composite fiber according to an embodiment of the present invention, which also illustrates an embodiment wherein a first fiber component element and a second fiber component element are adjacent to each other in the fiber axis direction. Fig. 10 is a perspective view schematically illustrating a composite fiber according to an embodiment of the present invention, which also illustrates an embodiment wherein the composite fiber has a sandwich structure. Fig. 11A, Fig. 11B and Fig. 11C are schematic views schematically illustrating a conventional PZT fiber and a smart board, the PZT fiber being embedded in a structure thereof. Fig. 12 is a schematic view schematically illustrating an example of a method for producing a conventional PZT fiber. Fig. 13A and Fig. 13B are schematic views schematically illustrating cases where a conventional smart board is used as a vibration sensor and exciter. DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION

[0017] A composite fiber according to an embodiment of the present invention will be described in more detail below. The description will be made with reference to the drawings where necessary. In the drawings, various elements of the present invention are schematically illustrated for understanding a composite fiber according to the present invention, so they may differ from the actual elements, for example, in terms of external appearance and size ratio.

[0018] The directions "upper" and "lower" (vertical direction), as well as "right" and "left" (horizontal direction), used directly or indirectly herein, are based on the drawings. Furthermore, the "cross-sectional view," also used directly or indirectly herein, is typically based on the cross-section of the fiber taken along a plane with a normal line in an axial direction of the fiber. Unless otherwise specified, the same or similar reference numerals may indicate the same or similar element or section, or have the same or similar meaning or content.

[0019] Numerical ranges, as used herein, are intended to include lower and upper limits unless otherwise specified, such as "less than / lower than" or "more than / greater than / higher than." This means that the numerical range from 1 to 10 can only be interpreted as including the lower limit of "1" and the upper limit of "10."

[0020] Furthermore, the fiber described in the present specification may be referred to as “SENf” in Japanese, so that the present invention may also refer to a composite “SENf”.

[0021] In the broadest sense, the term "composite fiber" according to the present invention means a fiber made of mutually different materials. This means that the composite fiber of the present invention is typically a fiber in which fiber component elements formed of mutually different materials are integrated with each other. In the broadest sense, the term "fiber" or "fiber body" means, but is not necessarily limited to, an elongated object having a length dimension 10 times or more, 100 times or more, or the like of its cross-sectional dimension, and the length dimension and cross-sectional dimension can be arbitrarily selected. In the narrower sense, the term "fiber" or "fiber body" has dimensions corresponding to those of a so-called "fiber," "microfiber," "nanofiber," or the like.Therefore, the cross-sectional dimension of the composite fiber according to the present invention may, for example, be on the order of millimeters, micrometers, nanometers, or the like. There are no particular restrictions on the shape of the "fiber." The cross-sectional view of the composite fiber may, for example, typically be circular, elliptical, rectangular, or the like, but is not necessarily limited thereto. The composite fiber may have an overall cross-sectional profile formed arbitrarily from a straight line, a curve, and / or a combination thereof.

[0022] The composite fiber of the present invention is characterized at least in that it is a ceramic fiber made of a “material having a volume resistivity of 5×10 -6 up to 5×10 6Ω·m" and a "ceramic material". This means that the composite fiber of the present invention is a fiber constructed to include a ceramic element, such a ceramic element being made of a "material having a volume resistivity of 5×10 -6 up to 5×10 6 Ω· m". The term "ceramic", as used herein, may also be referred to as "ceramics".

[0023] In particular, the composite fiber according to the present invention is made of fiber component elements made of at least two different materials and preferably comprises a first fiber component element made of a material having a volume resistivity of 5×10 -6 up to 5×10 6Ω·m, and a second fiber component element formed of a ceramic material. In other words, in a preferred embodiment, the “material having a volume resistivity of 5×10 -6 up to 5×10 6 Ω·m” of the first fiber component element and the “ceramic material” of the second fiber component element are combined to form a fiber body of the composite fiber.

[0024] The term "fiber component element" as used herein refers, in the broadest sense, to an element constituting a fiber body or fiber. In the narrower sense, the term "fiber component element" refers to a portion occupying at least a portion of a fiber body / fiber, from which a fiber body / fiber shape or such a thin or ultra-thin elongated shape is provided.

[0025] The composite fiber according to the present invention can also be expressed from another aspect. Specifically, the composite fiber made of fiber component elements made of at least two different materials includes a first fiber component element containing a semiconductor or metalloid material and a second fiber component element containing a ceramic material. That is, the "semiconductor or metalloid material" of the first fiber component element (hereinafter also referred to as "semiconductor / metalloid material") and the "ceramic" of the second fiber component element are combined to form a fiber body of the composite fiber.

[0026] In the composite fiber according to the present invention, the first fiber component element and the second fiber component element are adjacent to each other, thereby forming a fiber body. For example, the first fiber component element and the second fiber component element are adjacent to each other in a cross-sectional view taken along a plane whose normal line lies in the axial direction of the fiber. Preferably, the first fiber component element and the second fiber component element are integrated with each other to form a single fiber.

[0027] An example of a composite fiber according to the present invention is shown in Fig. 1A to 1C illustrates . Fig. 1A is an exemplary perspective view of the composite fiber 10. Fig. Figure 1B schematically illustrates a cross-section of the composite fiber 10 of Fig. 1A (in particular a cross-section taken along a direction perpendicular to the axial direction of the fiber), and Fig. Figure 1C schematically illustrates a cross-section through the IC-IC of Fig. 1B (in particular, a lateral cross-section taken along the axial direction of the fiber).

[0028] The composite fiber 10 of the present invention is made of a first fiber component element 1 and a second fiber component element 2. As illustrated in the drawings, the first fiber component element 1 and the second fiber component element 2 are adjacent to each other, so that a fiber body of the composite fiber is provided by the first and second fiber component elements. This means that the first fiber component element 1 has a volume resistivity of 5×10 -6 Ω·m to 5×10 6Ω·m and the second fiber component element 2, which includes a ceramic, are integrally combined to assume a fiber shape, thereby providing the composite fiber 10. The volume resistivity of the first fiber component element may be, for example, 1.0×10 -5 up to 1.0×10 6 Ω·m or 5×10 -5 up to 5×10 5 Ω·m. As can be seen from these descriptions, the term "contiguous" / "contiguous" as used herein preferably means an arrangement positioned adjacent to or in contact with each other, thereby forming a fiber. For example, the first fiber component element and the second fiber component element may be in close contact with each other such that an interface is located therebetween in a cross-sectional view of the fiber.

[0029] The term "volume resistivity" as used herein refers to a resistivity at a temperature of 23 ± 5 °C and a relative humidity of 50 ± 20% as temperature and humidity conditions. The volume resistivity can be measured according to JIS R 7609:2007. The volume resistivity can be a value measured by extracting or taking out only the first fiber component element from the composite fiber. In a simple way, the volume resistivity can be determined as a material before it is assembled into a fiber.

[0030] If the first fiber component element constituting the fiber body has a volume resistivity of 5 × 10 -6 up to 5×10 6Ω·m, the first fiber component element preferably corresponds to an element containing a semiconductor or metalloid material. In this case, where the first fiber component element is composed of a metal material having a lower volume resistivity than the semiconductor / metalloid, the first fiber component element may be based on a metal bond. On the other hand, when the first fiber component element is composed of the semiconductor or metalloid material according to the present invention, the first fiber component element may be an element based on a covalent bond. Accordingly, the first fiber component element comprising the material with the volume resistivity of 5×10 -6 up to 5×10 6Ω·m or the semiconductor / metalloid material has a relatively high tensile strength (i.e., it has a higher tensile strength than a metal element such as Ti) and can lead to further increased strength of the fiber. Thus, the fiber according to the present invention, which may correspond to a ceramic fiber, can be used as a piezoelectric fiber while having further increased strength therein.

[0031] In a preferred embodiment, the first fiber component element comprises such a material having a volume resistivity of 5×10 -6 up to 5×10 6Ω·m or the semiconductor / metalloid material has a relatively high elastic modulus. This means that the elastic modulus in the present invention is specified to be higher than that of the first fiber component element formed of a metal other than the semiconductor / metalloid. Thus, when a force is applied to the composite fiber of the present invention, the first fiber component element can effectively absorb the force. When an external force is applied to the composite fiber to generate a piezoelectric effect, the first fiber component element can preferably effectively receive and support the applied stress. Therefore, undesirable stress is less likely to be caused in the second fiber component element formed of ceramic, whereby the composite fiber of the present invention can be provided as a piezoelectric fiber that is less prone to breakage with high strength (i.e.,as a shatter-proof, high-strength piezoelectric fiber).

[0032] From this point of view, the composite fiber according to the present invention can exhibit higher strength and / or higher elasticity, making it easier to achieve a reduction in fiber diameter. The composite fiber of the present invention, which can have a reduced diameter (namely, a small cross-sectional dimension of the fiber), can be more suitably used as a piezoelectric fiber. For example, the composite fiber of the present invention can be provided as a fiber capable of detecting fine input sensing and driving power.

[0033] The term "semiconductor" as used herein broadly refers to a material that falls between a good conductor (e.g., metal) and an insulator (e.g., resin or glass). For example, the term "semiconductor" refers to a material whose electrical conductivity, resistivity, or the like has a value that lies between that of a "good conductor, such as metal," and that of an "insulator, such as resin or glass."

[0034] In the present invention, there is no particular limitation on the type of semiconductor of the first fiber component element, and it may be any elemental semiconductor (or a simple substance semiconductor), a compound semiconductor, an oxide semiconductor, or an organic semiconductor from the perspective of constituent elements. Furthermore, the semiconductor may be an intrinsic semiconductor corresponding to a high-purity semiconductor material, or an impurity semiconductor to which impurities or the like have been added. Furthermore, from the perspective of the wearer, the semiconductor of the first fiber component element may be an N-type semiconductor or a P-type semiconductor.

[0035] The constituent element of the semiconductor in the first fiber component element may be, for example, at least one element selected from the group consisting of carbon (C), silicon (Si), germanium (Ge), gallium (Ga), arsenic (As), indium (In), phosphorus (P), antimony (Sb), aluminum (Al), nitrogen (N), and the like.

[0036] The term "metalloid," as used herein, refers to a material whose chemical and physical properties lie between those of a metal and a non-metal, or a material that can serve as a combined material of a metal and a non-metal. The metalloid may also be a so-called "semimetal." The metalloid element in the first fiber component element may be, by way of example only, at least one element selected from the group consisting of silicon (Si), germanium (Ge), boron (B), arsenic (As), antimony (Sb), tellurium (Te), and astatine (At). As is apparent from the above description, the "metalloid" and "semiconductor" of the present specification may be interchangeable, depending on the nature of the specific element.This means that the material of the first fiber component element according to the present invention can be included in the category of metalloids and at the same time in the category of semiconductors and vice versa.

[0037] In the composite fiber according to the present invention, the first fiber component element and the second fiber component element may be adjacent to each other such that one of the first fiber component element and / or the second fiber component element is situated outside the other thereof. As in Fig. 1A to 1C, the first fiber component element 1 and the second fiber component element 2 may, for example, be adjacent to each other, with the second fiber component element 2 positioned relatively outside the first fiber component element 1. Alternatively, the first fiber component element 1 and the second fiber component element 2 may also be positioned inversely. This means that the first fiber component element may be positioned relatively outside the second fiber component element so that they are adjacent to each other. In either embodiment, the composite fiber according to the present invention can be provided as a fiber with increased strength because the first fiber component element has a relatively high tensile strength and / or a relatively high elastic modulus compared to the second fiber component element.The first fiber component element and / or the second fiber component element may have a shape that extends along the axial direction of the composite fiber. In one embodiment, both the first fiber component element and the second fiber component element extend along the axial direction of the composite fiber. For example, the first fiber component element and the second fiber component element may extend side by side or parallel to each other along the axial direction of the fiber.

[0038] If the “second fiber component element containing a ceramic” is placed outside the “first fiber component element containing a material having a volume resistivity of 5×10 -6 up to 5×10 6Ω·m or a semiconductor / metalloid”, the composite fiber of the present invention can be used so that the first fiber component element, which is relatively positioned inside the composite fiber, can serve for electrical connection. In this case, the second fiber component element, which is relatively located outside the composite fiber, can also serve for electrical connection, so that a piezoelectric effect associated with the second fiber component element, which includes the ceramic, is generated. Alternatively, if the “first fiber component element, which is a material with a volume resistivity of 5×10 -6 up to 5×10 6Ω m or a semiconductor / metalloid" is situated outside the "second fiber component element including a ceramic," the composite fiber of the present invention can be used so that the first fiber component element positioned relatively outside the composite fiber can serve for electrical connection. Similarly, the second fiber component element positioned relatively inside the composite fiber can also serve for electrical connection, so that a piezoelectric effect associated with the second fiber component element including the ceramic is generated. Thus, the composite fiber of the present invention can be more suitably used as a piezoelectric fiber.

[0039] The first fiber component element 1 is not necessarily limited to a single element in the composite fiber. That is, the first fiber component element may be made of a plurality of sub-fiber component elements. For example, the first fiber component element may be made of at least two fiber elements. Such a plurality of sub-fiber component elements enables the first fiber component element to have a more effective function in receiving and bearing the applied stress, which can facilitate providing the composite fiber of the present invention as a fiber with higher strength. There is no particular limitation on the number of sub-fiber component elements. The number of sub-fiber component elements may be, for example, 2 to 50, 2 to 40, 2 to 30, 2 to 20, or 2 to 10 per composite fiber.

[0040] In a cross-sectional view, as in Fig. 2, for example, a plurality of sub-fiber component elements 1' may be arranged as the first fiber component element 1 within a contour region of the second fiber component element 2. This means that the sub-fiber materials 1' of the first fiber component element 1 (hereinafter also referred to as "first sub-fiber materials") are positioned in the fiber region defined by the second fiber component element 2 of the composite fiber 10. In this case, the plurality of first sub-fiber materials in the interior of the fiber can cooperatively receive and bear the applied stress, which can facilitate imparting the higher strength to the composite fiber.

[0041] In the cross-sectional view of the composite fiber, the plurality of first sub-fiber materials may be arranged symmetrically to each other. As shown in Fig. 2, for example, the plurality of first sub-fiber materials 1' may be arranged within the contour region of the second fiber component element 2 such that the plurality of first sub-fiber materials 1' have a symmetrical relationship (e.g., a point-symmetrical or line-symmetrical relationship) with each other. With such a symmetrical arrangement, the first sub-fiber materials can receive and bear the applied stress in a more effective operation. The plurality of first sub-fiber materials may extend along the axial direction of the composite fiber. For example, the plurality of first sub-fiber materials may extend side by side or parallel to each other along the axial direction of the fiber.

[0042] As described above, the first fiber component member is preferably a fiber element having a relatively high tensile strength compared to that of the second fiber component member. The tensile strength of the first fiber component member may be, for example, 100 kgf / mm 2 or more. This means that the first fiber component element combined with the second fiber component element formed of ceramic in the composite fiber is a material having a tensile strength of, for example, 100 kgf / mm 2 or more. Such tensile strength can effectively contribute to reducing or preventing undesirable stresses that may be caused in the second fiber component member formed of ceramic, thereby making it possible to provide the composite fiber of the present invention as a piezoelectric fiber that is difficult to break (or fracture) and has high strength.

[0043] In a preferred embodiment, the tensile strength of the first fiber component element is 200 kgf / mm 2 or more. This means that the “first fiber component element with a volume resistivity of 5×10 -6 up to 5×10 6 Ω m or a semiconductor / metalloid material” combined with the second fiber component element formed of ceramic in the composite fiber, the tensile strength of, for example, 200 kgf / mm 2 or more, which can more effectively contribute to the realization of the fracture-resistant piezoelectric fiber with higher strength. There is no particular limitation on the upper limit of the tensile strength of the first fiber component element. The upper limit of the tensile strength of the first fiber component element can be, for example, 20,000 kgf / mm 2 , 10000 kgf / mm 2 , 5000 kgf / mm 2 , 2500 kgf / mm 2 , 2000 kgf / mm 2 , 1000 kgf / mm2 , 800 kgf / mm 2 or 500 kgf / mm 2 be.

[0044] The term "tensile strength" as used herein refers to a strength determined using a tensile testing machine for a prepared test piece in accordance with JIS R 7606:2000. For convenience, a value measured using a tensile testing machine (MST-1, manufactured by Shimadzu Corporation) may be adopted as "tensile strength".

[0045] The composite fiber according to the present invention, which comprises the first fiber component element made of the material having a volume resistivity of 5×10 -6 up to 5×10 6Ω·m or the semiconductor / metalloid material, may provide an advantageous effect with regard to, for example, electrical properties and / or a production process of the composite fiber due to the presence of such a first fiber component element.

[0046] The resistivity can be adjusted, for example, due to element doping and / or defect formation of the semiconductor / metalloid of the first fiber component element, and a desired stress can be introduced into a ceramic portion of the second fiber component element that is in contact with the first fiber component element. This means that the first fiber component element can be an at least partially doped element, thereby making it possible to provide the composite fiber of the present invention as a more suitable piezoelectric fiber with regard to stress application. The resistivity can also be adjusted by a pattern of the first fiber component element (e.g., the semiconductor / metalloid pattern), thereby making the composite fiber of the present invention more suitable with regard to stress application.

[0047] In a preferred embodiment, the material of the first fiber component element is composed of carbon and / or silicon. This means that the material has a specific volume resistivity of 5×10 -6 up to 5×10 6Ω m or the semiconductor / metalloid material in the first fiber component element may comprise at least one of carbon and silicon elements. Such a first fiber component element comprising at least one of the carbon and silicon elements is preferable in view of tensile strength, which can more effectively contribute to realizing the piezoelectric fiber that is hard to break (or fracture) and has high strength. Furthermore, the first fiber component element comprising at least one of the carbon and silicon elements can facilitate providing an advantageous effect with respect to a method for producing the composite fiber due to superior heat resistance of the first fiber component element.In particular, the material comprising at least one of the carbon and silicon elements in the first fiber component element is less susceptible to state changes or does not change its state even at high temperatures, which can more easily lead to a stabilized process during ceramic calcination of the second fiber component element. This can facilitate the provision of a desired fiber as a composite fiber.

[0048] The first fiber component element in the composite fiber can, for example, be composed primarily of carbon. The first fiber component element can, for example, be formed from carbon based on a graphite bond. The first fiber component element in the composite fiber can be formed from silicon carbide.

[0049] In a preferred embodiment, the first fiber component element is a carbon fiber and / or a SiC fiber (i.e., a silicon carbide fiber). Both the carbon fiber and the SiC fiber have significantly higher strength properties, such as tensile strength, than metals. In particular, the tensile strength of a Ti metal wire, for example, is approximately 48 kgf / mm 2 , while the tensile strength of carbon fiber is 500 to 700 kgf / mm 2 and the tensile strength of the SiC fiber 300 kgf / mm 2Accordingly, the first fiber component member (e.g., a plurality of first sub-fiber materials) can be more effective in receiving and supporting the applied stress, which can facilitate imparting higher strength to the composite fiber. Furthermore, the carbon fiber hardly undergoes any shape change even at a high temperature in a reducing atmosphere. Likewise, the SiC fiber hardly undergoes any shape change even at a high temperature in air and in a reducing atmosphere. Accordingly, the carbon fiber and the SiC fiber are stable even when the ceramic of the second fiber component member is calcined. Moreover, the carbon fibers and the SiC fibers (silicon carbide fibers) in particular have a thermal expansion coefficient close to that of ceramics.For example, the thermal expansion coefficient of each carbon and SiC fiber is closer to that of ceramic compared to that of metals such as nickel. These can contribute to the production process of the composite fibers becoming more desirable. This means that by raising and lowering the temperature in conjunction with the ceramic calcination of the second fiber component element to, for example, 1200°C, the difference in expansion / contraction between the first fiber component element and the second fiber component element can be appropriately reduced, thereby appropriately preventing undesirable delamination phenomena and facilitating the production of the desired composite fiber.

[0050] There are no particular restrictions on the type of carbon fiber. For example, a PAN-based carbon fiber and / or a pitch-based carbon fiber can be used as the carbon fiber. For example, the PAN-based carbon fiber can be obtained by carbonizing a PAN precursor (a polyacrylonitrile fiber). The pitch-based carbon fiber can be obtained by carbonizing a pitch precursor (a pitch fiber obtained from coal tar or petroleum heavy oil as a raw material). Therefore, a commercially available product can be used as the carbon fiber.The carbon fiber may be a fine or ultrafine member, a cross-sectional dimension of which is 2 to 50 µm, for example, 2 to 40 µm, 2 to 30 µm, 2 to 20 µm, 2 to 15 µm, 2 to 10 µm, 2 to 9 µm, 2 to 8 µm, or 2 to 5 µm, which can facilitate contributing to the reduction of the diameter of the composite fiber.

[0051] There are also no particular restrictions on the type of SiC fiber. For example, SiC fiber can be obtained by vapor-phase decomposition of an organosilicon compound. Alternatively, SiC fiber can be obtained by vapor-phase decomposition of silicon tetrachloride and a hydrocarbon or carbon tetrachloride. SiC fiber can also be obtained by thermally oxidizing a silicon-containing polycarbosilane and then calcining the resulting product. Therefore, any commercially available product can be used as the SiC fiber. The SiC fiber may be a fine or ultrafine member, a cross-sectional dimension of which is 2 to 50 µm, for example, 2 to 40 µm, 2 to 30 µm, 2 to 20 µm, 2 to 15 µm, 2 to 10 µm, 2 to 9 µm, 2 to 8 µm, or 2 to 5 µm, which can facilitate contributing to the reduction of the diameter of the composite fiber.

[0052] In the composite fiber according to the present invention, the first fiber component element may be provided as a fiber element having high tensile strength as described above. From another perspective, the first fiber component element may also be provided as a member having a higher specific strength ([gf / D]). For example, the first fiber component element may have a specific strength higher than that of metal Ti or the like as described above, and / or it may have a specific strength higher than that of a ceramic such as barium titanate.In this context, the present invention can provide the first fiber component element as an element capable of adjusting its resistivity (for example, capable of adjusting its resistivity relatively easily by adding a dopant with respect to a semiconductor material) and also having a high specific strength. Further, the first fiber component element can be an element having high thermal stability, capable of having an adjusted resistivity thereof and a high specific strength. As such, the composite fiber according to a preferred embodiment of the present invention comprises the composite semiconductor or metalloid material having high thermal stability, capable of having the adjusted resistivity and also having a high specific strength.

[0053] In a preferred embodiment, the second fiber component element comprises a ceramic sintered body. This means that the composite fiber may comprise a sintered body of the ceramic in the second fiber component element combined with the first fiber component element made of a material having a volume resistivity of 5×10 -6 up to 5×10 6Ω m or the semiconductor / metalloid. Such a ceramic sintered body is preferable at least in that the composite fiber can suitably serve as a ceramic fiber. For example, the ceramic sintered body of the second fiber component element is preferable in view of the piezoelectric effect of the composite fiber to be used as a piezoelectric fiber. In the present specification, the "ceramic sintered body" may correspond to a ceramic (e.g., a ceramic crystal) formed by calcining at least the "ceramic component" described below. In other words, the "ceramic component" is preferably a component that can construct the "ceramic sintered body." The "ceramic component" is also preferably a component that can be contained in the "ceramic sintered body."

[0054] There is no particular limitation on the “ceramic component” (ceramic component element) contained in the second fiber component element, as long as it is a component (element) capable of providing the ceramic (ceramic crystals, particularly in the form of metal oxides).The ceramic component is, for example, at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), yttrium (Y), zirconium (Zr), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), boron (B), aluminum (Al), silicon (Si), indium (In), tin (Sn), antimony (Sb), barium (Ba), tantalum (Ta), tungsten (W), lead (Pb), bismuth (Bi), lanthanum (La), cesium (Ce), neodymium (Nd), samarium (Sm), gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er), oxygen (O), carbon (C), nitrogen (N), sulfur (S), phosphorus (P), fluorine (F) and chlorine (Cl) (the (hereinafter referred to as "ceramic element"). In an exemplary embodiment, the ceramic component of the composite fiber may be formed from titanium, barium, and oxygen.In another exemplary embodiment, the ceramic component of the composite fiber may be formed from bismuth, sodium, titanium, and oxygen.

[0055] The ceramic component may include a glass component. Examples of glass components include at least one selected from the group consisting of soda-lime glass, potash glass, borate glass, borosilicate glass, barium borosilicate glass, zinc borate glass, barium borate glass, bismuth borosilicate glass, bismuth zinc borate glass, bismuth silicate glass, phosphate glass, aluminophosphate glass, and zinc phosphate glass.

[0056] In a preferred embodiment, the ceramic of the second fiber component element is a ceramic selected from the group consisting of barium titanate, sodium bismuth titanate, and apatite. This means that the composite fiber may comprise the ceramic material selected from the group consisting of barium titanate, sodium bismuth titanate, and apatite as the ceramic of the second fiber component element in combination with the first fiber component element, which is made of the material having a volume resistivity of 5×10 -6 up to 5×10 6Ω m or the semiconductor / metalloid. For example, the ceramic barium titanate, the sodium bismuth titanate, and the apatite may be in the form of a sintered body. Such a ceramic can be obtained by calcination, which can further enhance the effect of the present invention. That is, despite a high-temperature calcination process, the first fiber component element of the composite fiber according to the present invention can have preferable properties for the calcination process in terms of its thermal stability and / or its thermal expansion coefficient, whereby the composite fiber can be provided more stable and / or with high strength as a ceramic fiber composed of the ceramic sintered body as described above.

[0057] The ceramic sintered body may contain crystal grains or microcrystals. There is no particular limitation on the crystal grain size of the ceramic sintered body. The crystal grain size in the ceramic sintered body may be, for example, 0.1 µm to 10 µm. In this specification, the crystal grain size refers to the maximum dimension of the crystal grain or microcrystal in a cross-sectional view. The ceramic sintered body may be a polycrystalline body made of a ceramic (or a ceramic component / constituent).

[0058] The size of the crystal grain in the ceramic sintered body may depend on the ceramic component / constituent, and the grain size of the powder of the ceramic component before calcination may be, for example, 0.05 μm to 5 μm. The presence of the crystal grains in the composite fiber can be confirmed from an image or the like obtained by photographing a region including a target area using a transmission electron microscope, a scanning electron microscope, a scanning ion microscope, or the like. The presence or absence of the crystal grains can be determined by observing a contrast difference due to a difference in crystal orientation in the image or the like.

[0059] In a case where the ceramic of the composite fiber is formed of barium titanate, sodium bismuth titanate, or apatite, the second fiber component element may be, for example, the crystal grain(s) or microcrystal(s) of barium titanate (BaTiO 3 ) (BT), sodium bismuth titanate ((Bi 1 / 2 N / a 1 / 2 )TiO 3 ) (BNT) or apatite.

[0060] There is no particular restriction on the specific type of apatite in the second fiber component element, as long as it generally belongs to the apatite category. In a suitable case where apatite is used for the composite fiber, the second fiber component element includes an apatite component and / or a component derived therefrom. The apatite may be a ceramic made of a calcium phosphate-based functional inorganic material, which also contains phosphorus (P) and calcium (Ca) as main elements. In a case where the second fiber component element includes apatite, the second fiber component element may have a special feature in that the ceramic is used for a piezoelectric fiber, while the apatite is a ceramic normally recognized as a biomaterial.In a preferred embodiment, the apatite in the second fiber component member can be used as a ceramic-based biomaterial. In a case where the apatite material as described above is used for the second fiber component member, a more suitable ceramic fiber can be provided. For example, when the apatite material is used for the second fiber component member, high mechanical strength and / or fracture toughness are facilitated, which can be applied to the second fiber component member, and electronic properties, such as generation and control of charge-holding capacity, are also facilitated, which can be appropriately transferred to the composite fiber.

[0061] The apatite used for the second fiber component element can, for example, be selected at least from the group consisting of a fluorapatite, a chlorapatite, a hydroxyapatite, and an oxyapatite. Fluorapatite (FAp) is represented by the following chemical formula: Ca 5 (PO 4 ) 3 F and can also be referred to as a fluoroapatite or a fluoroapatite. Chlorapatite (CAp) is represented by the following chemical formula: Ca 5 (PO 4 ) 3 Cl and can also be referred to as chlorapatite or chloroapatite. There is no particular restriction regarding the type of hydroxyapatite (HAp). Hydroxyapatite (HAp), for example, can be represented by the following chemical formula: Ca 5 (PO 4 ) 3 (OH) 2and can also be called "Suisan Apatite" or "Suisan Rinkaiseki" in Japanese. Oxyapatite (OHA) can be represented by the following chemical formula: Ca 5 (PO 4 ) 3O. Hydroxyapatite and / or oxyapatite is preferably used as the apatite for the second fiber component element. Accordingly, the second fiber component element may include the hydroxyapatite and / or oxyapatite or a component derived therefrom. Such hydroxyapatites and oxyapatites are generally known as biomaterials. The composite fiber comprising the hydroxyapatite and / or oxyapatite is characterized in that a bio-based ceramic is used for the piezoelectric fiber. The hydroxyapatite and / or oxyapatite of the second fiber component element, or a component derived therefrom, is likely to impart not only high mechanical strength and fracture toughness to the composite fiber, but also superior electronic properties, such as charge-holding capacity, to the composite fiber.

[0062] The ceramic of the second fiber component member may be provided as a composite material with a resin. The second fiber component member may be provided, for example, by molding a raw material including a ceramic component and a resin component. The resin is, for example, a polymer material. There is no particular limitation on the type of polymer as long as the resin corresponds to the polymer material. As the resin, a thermoplastic resin and / or a thermosetting resin may be used, respectively. A phenolic resin, an epoxy resin, a bismaleimide resin, a polypropylene resin, a polyimide resin, a polyamideimide resin, and / or an acrylonitrile resin may be used, for example. Such a resin material may be combined with one or more hindered amine- or triazine-based additives therein. The ratio of ceramic to resin (ie,The ceramic / resin ratio in the composite material may, for example, be 99 / 1 to 1 / 99 on a volume basis. Such a ceramic / resin ratio may, for example, only be in the range of 64 / 36 to 1 / 99, 30 / 70 to 1 / 99, or 20 / 80 to 1 / 99.

[0063] There is no particular limitation on the cross-sectional dimension of the composite fiber according to the present invention, as long as it can be a dimension corresponding to a fiber. That is, the composite fiber according to a preferred embodiment of the present invention has such a fiber dimension in cross-sectional view that it can have, for example, a cross-sectional dimension on the order of µm. For example, the fiber diameter of the composite fiber can be 500 µm or less (specifically, 1 µm or more and 500 µm or less). Thus, the fiber diameter of the composite fiber may be 400 µm or less (in particular 1 µm or more and 400 µm or less), 300 µm or less (in particular 1 µm or more and 300 µm or less), 200 µm or less (in particular 1 µm or more and 200 µm or less) and, for example, 50 µm to 100 µm.In the present invention, the first fiber component element as described above can facilitate the achievement of a diameter reduction (ie, a size reduction) compared to conventional PZT fibers. The term "fiber diameter" as used herein refers to the composite fiber of the present invention and means the largest dimension (e.g., diameter) in a cross-section taken along a direction perpendicular to the axial direction of the fiber.

[0064] In the composite fiber according to the present invention, there is no particular limitation on the ratio of the cross-sectional area of ​​the first fiber component element to the second fiber component element. For example, the value of the area of ​​the "first fiber component element / area of ​​the second fiber component element" may be 1 / 99 to 99 / 1 in a cross-sectional view. The cross-sectional area of ​​the first fiber component element / the cross-sectional area of ​​the second fiber component element may be 1 / 8 to 8 / 1, for example only.

[0065] The composite fiber according to the present invention can preferably have increased strength than conventional PZT fibers. This means that the composite fiber according to the present invention has more suitable strength, even if it is a ceramic fiber capable of serving as a piezoelectric fiber. As a whole fiber, for example, the composite fiber of the present invention has a tensile strength (e.g., elongation at break) of preferably 5 kgf / mm 2 or more, for example 6 kgf / mm 2 or more, 10 kgf / mm 2 or more, 14 kgf / mm 2 or more, or 20 kgf / mm 2 or more. For example only, the tensile strength (e.g., elongation at break) of the entire composite fiber according to a preferred embodiment of the present invention is 50 kgf / mm 2 or more and 400 kgf / mm 2 or less.

[0066] The composite fiber according to the present invention can be embodied in various embodiments. (Core-shell structure 1 as mutual disposition mode of the first and second fiber component elements)

[0067] The composite fiber of the present invention can take various forms as long as the first and second fiber component elements are adjacent to each other in a positional relationship. In this regard, the first fiber component element and the second fiber component element may be adjacent to each other such that one of them is positioned outside the other, as described above. In the cross-sectional view of the composite fiber, the first fiber component element may be at least partially surrounded by the second fiber component element.

[0068] The composite fiber made of the first and second fiber component elements may, for example, have a core-sheath structure. In the exemplary embodiment shown in the Fig. 3A and Fig. 3B, a core part is provided by the first fiber component element 1, and a cladding part is provided by the second fiber component element 2. Specifically, the first fiber component element 1 of the core part occupies a relatively larger cross-sectional area than the second fiber component element 2 of the cladding part, as in the illustrated embodiment. This allows the part of the composite fiber that effectively absorbs (e.g., effectively receives and supports) the applied stress to have a larger proportion, thereby making it less likely that undesirable stress will be caused in the second fiber component element upon application of an external force thereto, which can lead to achieving a fracture-resistant (or shatter-proof) fiber. This means that the composite fiber serving as a piezoelectric fiber can be provided with high strength. (Core-shell structure 2 as mutual disposition mode of the first and second fiber component elements)

[0069] The composite fiber according to the present embodiment has a core-clad structure similar to the above embodiment, wherein the second fiber component element 2 of the cladding part occupies a relatively larger cross-sectional area than the first fiber component element 1 of the core part (see Fig. 4A and Fig. 4B). This means that, as in the exemplary embodiments of Fig. 4A and Fig. 4B, the cross-sectional contour dimension of the first fiber component element 1 provided as the core part is less than half the cross-sectional contour dimension of the second fiber component element 2 provided as the cladding part (i.e., less than half the cross-sectional dimension of the entire composite fiber 10). This can, in particular, result in the composite fiber exhibiting a more efficient piezoelectric effect than a suitable piezoelectric fiber. (First fiber component element in multicore / fine fiber form as mutual disposition mode of the first and second fiber component elements)

[0070] The composite fiber according to this embodiment has the core-cladding structure as described above, wherein the number of the first fiber component elements of the core part is not one, but two or more. The composite fiber 10 as shown in Fig. 5A and Fig. 5B includes the two fiber component elements 1 serving as the core part. The number of the first fiber components serving as the core part is not limited to two, and thus the composite fiber 10 may have a shape as shown in Fig. 6A and Fig. 6B. Such an exemplary embodiment of Fig. 6A and Fig. 6B may be one in which fine or ultrafine first fiber component elements are included. This means that in the Fig. 6A and Fig. 6B, a plurality of first fiber component elements 1' each having a fine or ultrafine diameter are provided in the fiber 10. As shown in Fig. 6A and Fig. As illustrated in Fig. 6B, the sub-fiber materials 1' may be provided parallel to each other, for example, like the first fiber component element 1 in the fiber region formed by the second fiber component element 2. In this form, a plurality of the first fiber component elements (i.e., a plurality of the sub-fiber materials 1' having the high tensile strength) collectively absorb the stress applied to the composite fiber (e.g., cooperatively receive and support), thereby facilitating the provision of the high-strength piezoelectric fiber.

[0071] With respect to the plurality of first fiber component elements, various arrangement forms thereof are possible in a cross-sectional view. In the present invention, the first fiber component element, such as a carbon fiber and / or a SiC fiber, may be provided in particular as a fine or ultrafine fiber material, whereby the first fiber component element can be provided in a variety of forms occurring in the single composite fiber of the present invention. As shown in Fig. 6A and Fig. 6B, a plurality of first fiber component elements (ie, a plurality of sub-fiber materials 1') may, for example, have a symmetrical arrangement relationship with each other. (Biaxial form as mutual disposition mode of the first and second fiber component elements)

[0072] The composite fiber according to this embodiment does not have a uniaxial shape. The composite fiber 10, as shown in Fig. 7, for example, has a biaxial shape as a whole fiber.

[0073] In such a composite fiber 10, one of the first and / or second fiber component elements may be located relatively outside and the other of the first and second fiber component elements may be located relatively inside. In the composite fiber 10, as shown in Fig. 7, the second fiber component element 2 is positioned relatively outside and the first fiber component element 1 is positioned relatively inside. In other words, the fiber body is constructed with an adjacent shape of the fiber component elements, in which the first fiber component element 1 and the second fiber component element 2 are opposite each other in a direction orthogonal / perpendicular to the axial direction of the fiber. In one embodiment, as shown in Fig. For example, as illustrated in Figure 7, a high-strength material such as carbon and / or SiC can be positioned in a fiber region where tension / compression of the composite fiber is most likely to be induced. This can facilitate providing a piezoelectric fiber that is resistant to bending (e.g., left and right bending). (Doping embodiment of the first fiber component elements)

[0074] The composite fiber according to this embodiment is configured such that the first fiber component element is at least partially doped. In the composite fiber, for example, the first fiber component element including the semiconductor material may be at least partially doped. Since the resistivity or the like of the semiconductor material in the first fiber component element can be adjusted by doping (i.e., by implanting additives, ions, or impurities), it is possible to facilitate the provision of a desired composite fiber in terms of its resistivity and the like. There is no particular limitation on the type of dopant (i.e., additives, ions, or impurities to be implanted). The dopant may, for example, be selected from the group consisting of boron, nitrogen, aluminum, and phosphorus.

[0075] In a preferred embodiment, the first fiber component element is formed at least partially from the semiconductor, such as the N-type semiconductor and / or the P-type semiconductor. The first fiber component element may, for example, be formed at least partially from the N-type semiconductor or the P-type semiconductor due to doping with respect to an intrinsic semiconductor.

[0076] In a case where the first fiber component element is made specifically of the semiconductor, a doping region (e.g., a doping layer) may be provided at the interface between the semiconductor of the first fiber component element and the ceramic of the second fiber component element. With this doping region, the composite fiber of the present invention can be provided as a fiber capable of functioning in response to the application of a voltage through the doping layer of the semiconductor or metal at a semiconductor / ceramic interface. In a case of using the doping region (e.g., the doping layer), a gate electrode element, a drain electrode element, a source electrode element, and the like may be provided as associated elements, respectively. (Variation form as electronic component element / part)

[0077] The composite fiber according to this embodiment may, for example, have a structure as shown in each of the Fig. 8A to 8D as an electronic component element / part.

[0078] The composite fiber 20, as in Fig. 8A illustrates a concentric structure. This means that the composite fiber has a circular cross-section and also has a structure such that the central portion 21 and the outer portion 22 are arranged substantially concentrically. The cross-sectional shapes illustrated in the drawings are circular and concentric, but there is no particular limitation on the cross-sectional shape of the composite fiber.

[0079] In the composite fiber 20, one of the central portion 21 and / or the outer portion 22, which form concentric circles, may be one of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic," and the other of the central portion 21 and the outer portion 22 may be the other of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic." In the composite fiber 20, the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic" may be in close contact with each other to form an interface therebetween. Fig. 8A can be a fiber diameter D a(maximum dimension or maximum diameter) shown in this drawing along a line AA' may be, for example, 500 µm or less, and more particularly 1 µm or more and 500 µm or less.

[0080] The composite fiber 30, as in Fig. 8B has a fiber structure in which the outer portion thereof is partially cut. That is, the composite fiber 30 has a structure such that an outer portion 32a having a substantially C-shaped (or substantially crescent-shaped) cross section and an outer portion 32b having a substantially inverted C-shaped (or substantially crescent-shaped) cross section (hereinafter, the outer portions 32a and 32b are collectively referred to as an "outer portion 32") are spaced on a central portion 31 having a substantially circular cross section. The cross-sectional shape of the composite fiber 30 is not particularly limited to the illustrated shape.

[0081] In the composite fiber 30, one of the central portion 31 and / or the outer portion 32 is one of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic," and the other of the central portion 21 and the outer portion 22 is the other of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic." In the composite fiber 30, the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic" may be in close contact with each other to form an interface therebetween.

[0082] The “semiconductor / metalloid” or “ceramic” of the outer portion 32 may be the same or different in the outer portions 32a and 32b.

[0083] In Fig. 8B can be a fiber diameter D b (maximum dimension or maximum diameter) shown in this drawing along a line BB' may be, for example, 500 µm or less, and more particularly 1 µm or more and 500 µm or less.

[0084] The composite fiber 40, as in Fig. 8C has a fiber structure in which half of the outer portion thereof is not provided. That is, the composite fiber 40 has a structure such that the outer portion 42 having a substantially C-shaped (or substantially crescent-shaped) cross section is arranged on a part of the central portion 41 having a substantially circular cross section. The cross-sectional shape of the composite fiber 40 is not particularly limited to the illustrated shape.

[0085] In the composite fiber 40, one of the central portion 41 and / or the outer portion 42 is one of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic," and the other of the central portion 41 and the outer portion 42 is the other of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic." In the composite fiber 40, the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic" may be in close contact with each other to form an interface therebetween.

[0086] In Fig. 8C can be a fiber diameter D c(maximum dimension or maximum diameter) shown along a line CC' in this drawing may be, for example, 500 µm or less, and more particularly 1 µm or more and 500 µm or less.

[0087] The composite fiber 50, as in Fig. 8D illustrates a fiber structure including an intermediate layer therein. That is, the composite fiber 50 has a substantially circular cross-section and has a structure such that the central portion 51, the outer portion 52, and the intermediate layer 53 positioned therebetween are arranged substantially concentrically. The cross-sectional shape of the composite fiber 50 is not particularly limited to a circular or concentric shape.

[0088] In the composite fiber 50, one of the central portions 51 and / or the outer portion 52 is one of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic," and the other of the central portion 51 and the outer portion 52 is the other of the "first fiber component element formed of a semiconductor / metalloid" and the "second fiber component element formed of a ceramic." There is no particular limitation on the material of the intermediate layer 53, and it may be composed of at least one element selected from the group consisting of a metal, a ceramic, a metalloid, and a semiconductor.In the composite fiber 50, the “first fiber component element formed of a semiconductor / metalloid and provided in either the central portion 51 and / or the outer portion 52” and the “second fiber component element formed of a ceramic and provided in either the central portion 51 and the outer portion 52” may be in contact with each other with the intermediate layer 53 interposed therebetween.

[0089] In Fig. 8D can be a fiber diameter D d (maximum dimension or maximum diameter) shown in this drawing along a line DD' may be, for example, 500 µm or less, and more particularly 1 µm or more and 500 µm or less.

[0090] There is no particular limitation on the method for producing the composite fiber of the present invention, and thus the composite fiber can be produced by appropriately using a conventional ceramic calcination technique or the like.

[0091] The composite fiber made of the integrally adjacent first and second fiber component elements can be produced, for example, by preparing a paste consisting of the above-described “material having a volume resistivity of 5×10 -6 up to 5×10 6Ω m or a semiconductor / metalloid material”, optionally together with a sintering aid, a common material, a binder resin, a solvent, a dispersant and / or a plasticizer, and also another paste formed from a raw material including the above-described ceramic component (ceramic member) optionally together with a sintering aid, a common material, a binder resin, a solvent, a dispersant and / or a plasticizer (hereinafter also referred to as “ceramic raw material paste”), and then shaped in a suitable manner, followed by calcination (for example, normal pressure calcination or pressure calcination).In this context, each paste can be formed into the desired shape by using, for example, a multi-nozzle (compound spinneret such as a double nozzle and a triple nozzle) and / or a forming tool.

[0092] In a case where the second fiber component member is formed by the calcination as described above, the first fiber component member may also be formed by the calcination, and thus the composite fiber of the present invention may be a co-sintered fiber of the “material having a volume resistivity of 1×10 -5 up to 1×10 6Ω m or a semiconductor / metalloid material" and the "ceramic material". In the case of the co-sintered fiber, it is preferable that the second fiber component element comprises a sintered body and the first fiber component element also comprises a sintered body. In this case, an interface formed between the sintered bodies of the first and second fiber component elements may be due to crystal grains. In a preferred embodiment, such an interface may have a "surface roughness" and thus be a non-linear interface (alternatively, an interface having a roughness, a line roughness, a surface roughness, or irregularities) that is non-linear in the cross-sectional view. In other words, the interface between the first fiber component element and the second fiber component element may have a curved line shape in a cross-sectional view of the fiber.This interface can effectively contribute to preventing delamination between the first fiber component element and the second fiber component element and / or improving the strength of the composite fiber.

[0093] In a case where the first fiber component element in the composite fiber is formed of a fiber such as a carbon fiber and / or a SiC fiber, for example, a commercially available carbon fiber and / or SiC fiber can be used. That is, the desired composite fiber can be provided by appropriately combining such carbon fibers and / or SiC fibers with the ceramic raw material paste and then calcining the same. Alternatively, the desired composite fiber can be provided by combining such carbon fibers and / or SiC fibers with a resin raw material containing a ceramic component and then molding the same or the like.

[0094] Although some embodiments of the present invention have been described herein, they are for illustrative purposes only and are exemplary of typical embodiments. The composite fiber according to the present invention is not limited to these embodiments. It would be readily appreciated by those skilled in the art that various changes may be made to the foregoing embodiments without departing from the scope of the disclosure.

[0095] In the above description, for example, reference is made to the drawings in which the first fiber component element and the second fiber component element are adjacent to each other in particular in the radial / diameter direction of the composite fiber, but the present invention is not necessarily limited thereto. The composite fiber may have a structure such that the first fiber component element and the second fiber component element are adjacent to each other and aligned with each other in the axial direction of the fiber. In the composite fiber 60, as shown in Fig. 9, the first fiber component element 61 and the second fiber component element 62 are combined in contact with each other so as to be aligned in the axial direction of the fiber.

[0096] In the above description, reference is made to some of the drawings in which the composite fiber has a concentric structure, but the present invention is not necessarily limited thereto. The composite fiber may have a sandwich structure. This means that one of the first fiber component element and / or the second fiber component element may be sandwiched by the other. The composite fiber 70, as shown in Fig. 10, has a shape such that the second fiber component element 72, which is formed of ceramic, is sandwiched between the first fiber component elements 71 made of semiconductor / metalloid. Such a composite fiber may have a rectangular or square shape in cross-sectional view, as shown in Fig. 10 illustrates .

[0097] Furthermore, the first fiber component element and the second fiber component element in the composite fiber according to the present invention may be specialized only for the semiconductor / metalloid material and the ceramic material. This means that in the composite fiber according to a preferred embodiment of the present invention, the first fiber component element may consist only of the semiconductor or metalloid material, and the second fiber component element may consist only of the ceramic material. Nevertheless, the first fiber component element and the second fiber component element in the present invention allow the presence of an unavoidable or accidental component (i.e., an unavoidable or accidental component and / or a component material) that may be unavoidably or accidentally incorporated at the time of forming the elements and / or producing the composite fiber (e.g.,trace or ultra-trace amount of the unavoidable or adventitious component, etc.). INDUSTRIAL APPLICABILITY

[0098] The composite fiber according to the present invention can be used as various piezoelectric fibers. The composite fiber according to the present invention can also be used as a fiber-shaped electronic component element / electronic part and the like. The composite fiber of the present invention can be used, for example, for a sensor, particularly a vibration sensor, an exciter, or the like, used in a structure such as a building, an automobile, a ship, and / or an aircraft. LIST OF REFERENCE SYMBOLS 1 First fiber component element 1' Sub-fiber component elements (sub-fiber material of the first fiber component element) 2 Second fiber component element 10, 20, 30, 40, 50, 60, 70 composite fiber 21, 31, 41, 51 middle section 22, 32, 42, 52 outer section 53 Intermediate section 61 First fiber component element 62 Second fiber component element 71 First fiber component element 72 Second fiber component element 100 PZT fiber 101 Metal Wire / Thin Metal Wire 102 Thin PZT layer / PZT film 103 Nozzle 104 Wire guide 105 PZT paste 200 Smart Board 201 Carbon fiber reinforced plastic (CFRP) prepreg 202 Structure QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2003-12829

[0003] JP 2005-171752

[0003] JP 2004-15489

[0003] JP 2005-59552

[0003] JP 2005-313715

[0003] JP 2010-198092

[0003] Cited non-patent literature

[0000] POLYMERS” July issue (Vol. 57, No. 7, 2008) of The Society of Polymer Science, Japan

[0009] JIS R 7609:2007

[0029] JIS R 7606:2000

[0044]

Claims

[1] Composite fiber which has: a first fiber component element made of a material having a volume resistivity of 5 × 10 -6 up to 5×10 6 Ω·m is formed; and a second fiber component element comprising a ceramic material, wherein the first fiber component element and the second fiber component element are adjacent to each other such that the first and second fiber component elements form a fiber body. [2] Composite fiber which has: a first fiber component element comprising a semiconductor or metalloid material; and a second fiber component element comprising a ceramic material, wherein the first fiber component element and the second fiber component element are adjacent to each other such that the first and second fiber component elements form a fiber body. [3] The composite fiber according to claim 1 or 2, wherein the first and second fiber component elements are adjacent to each other such that the first and / or second fiber component elements are located outside the other of the first and second fiber component elements. [4] The composite fiber according to any one of claims 1 to 3, wherein in a cross-sectional view of the composite fiber, the first fiber component element is at least partially surrounded by the second fiber component element. [5] The composite fiber according to any one of claims 1 to 4, wherein the first fiber component element is made of a plurality of sub-fiber component elements. [6] The composite fiber of claim 5, wherein in a cross-sectional view of the composite fiber, the plurality of sub-fiber component elements are arranged within a contour region of the second fiber component element. [7] The composite fiber according to any one of claims 1 to 6, wherein the first fiber component member has a tensile strength of 100 kgf / mm 2 or more. [8] The composite fiber according to any one of claims 1 to 7, wherein the first fiber component member has a tensile strength of 200 kgf / mm 2 or more. [9] Composite fiber according to one of claims 1 to 8, wherein the material of the first fiber component element comprises carbon and / or silicon. [10] A composite fiber according to any one of claims 1 to 9, wherein the first fiber component element is an at least partially doped element. [11] The composite fiber according to any one of claims 1 to 10, wherein the second fiber component element comprises a ceramic sintered body. [12] Composite fiber according to any one of claims 1 to 11, wherein a ceramic component of the ceramic material is at least one selected from a group consisting of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), yttrium (Y), zirconium (Zr), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), boron (B), aluminum (Al), silicon (Si), indium (In), tin (Sn), antimony (Sb), barium (Ba), tantalum (Ta), tungsten (W), lead (Pb), bismuth (Bi), lanthanum (La), cesium (Ce), neodymium (Nd), samarium (Sm), gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er), oxygen (O), carbon (C), nitrogen (N), sulfur (S), phosphorus (P), fluorine (F) and chlorine (Cl). [13] The composite fiber according to any one of claims 1 to 12, wherein the ceramic material is one selected from a group consisting of barium titanate, sodium bismuth titanate and apatite. [14] The composite fiber according to any one of the preceding claims, wherein the composite fiber has an intermediate layer between the first component member and the second fiber component member, and the first fiber component member and the second fiber component member are in contact with each other with the intermediate layer disposed therebetween. [15] Composite fiber according to one of claims 14, wherein the material of the intermediate layer is composed of at least one element selected from the group consisting of a metal, a ceramic, a metalloid and a semiconductor. [16] A composite fiber according to any one of the preceding claims, wherein the first fiber component element and the second fiber component element are integrated with each other to form a single fiber.

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