JP2022012827A - Composite filler, resin composition containing the same, high polymer composite piezoelectric body, and piezoelectric device, as well as manufacturing method of composite filler - Google Patents

Abstract

To provide a filler for polymer composite having high voltage output constant, a filler for polymer composite piezoelectric body provided with high voltage constant and high voltage output constant in combination, and a method of manufacturing the filler for polymer composite piezoelectric body provided with high voltage constant and high voltage output constant.SOLUTION: A composite filler comprising a metal oxide fiber having an average fiber diameter of 0.1 to 10 μm and an aspect ratio of 2 or larger, and a piezoelectric ceramic particle having an average particle size of 0.01 to 200 μm and an aspect ratio smaller than 2, and a polymer composite piezoelectric body made of a resin composition containing the composite filler and the polymer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a composite filler, a resin composition containing the composite filler, a polymer composite piezoelectric body, and a piezoelectric element. The present invention also relates to a method for producing a composite filler.

Piezoelectric ceramics such as barium titanate and lead zirconate titanate have excellent piezoelectric and dielectric properties, and are therefore applied to sensors, power generation elements, actuators, acoustic devices, capacitors, and the like. Piezoelectric ceramics have excellent piezoelectric properties, dielectric properties, and high heat resistance, but are hard and brittle, so that they have poor flexibility and are difficult to increase in area and process. In order to solve such a problem, a polymer composite piezoelectric body in which a polymer is filled with piezoelectric ceramic particles as a filler is used. Such a polymer composite piezoelectric body is attracting attention as a material having both excellent flexibility and processability of a polymer and excellent piezoelectric properties and dielectric properties of piezoelectric ceramic particles. By changing the composition, shape, compounding ratio, etc. of the sex ceramic particles, it is possible to design the material according to the purpose.

For example, Patent Document 1 describes the dielectric property of a titanium acid metal salt fiber having a fiber length of 1 to 1000 μm and a fiber diameter of 0.01 to 10 μm represented by the general formula MO · n (Ti, X) О ₂ and a binder. Alternatively, a composition having piezoelectricity is described. Further, Patent Document 2 describes a metal oxide fiber made of ceramics containing a titanium element and having an average fiber diameter of 50 to 1500 nm. When such a filler having a large aspect ratio typified by a fibrous form is used, a large piezoelectric constant can be easily obtained as compared with a filler having a small aspect ratio such as a particle form, but the relative permittivity is increased. There is a problem that it is difficult to obtain a large voltage output constant. Further, a filler having a large aspect ratio has a problem that the productivity is remarkably low and the cost is high.

On the other hand, in Patent Document 3, a polymer non-woven fabric holding or blending piezoelectric ceramic particles and a polymer resin sheet containing piezoelectric ceramic particles are laminated so as to include at least one layer of the polymer non-woven fabric. A piezoelectric element made of a laminated body, wherein the laminated body has a power generation amount or more generated from a laminated body in which one layer of the polymer resin sheet is laminated on each of two main plane sides of the one layer of the polymer non-woven fabric. A piezoelectric element characterized by being a laminate capable of realizing the amount of power generated in the above is described, and the average diameter of the fibers constituting this polymer non-woven fabric is 0.05 to 5 μm, and the piezoelectric element is 30 to 60% by volume. It is stated that the piezo particles are retained or blended. However, since such a polymer non-woven fabric and the fiber portion constituting the polymer are made of a polymer material, the electric charge and vibration generated by the piezoelectric ceramic particles cannot be efficiently transmitted, and high piezoelectric characteristics can be obtained. There is a problem that it is difficult.

Japanese Unexamined Patent Publication No. 9-002868 Japanese Unexamined Patent Publication No. 2007-32177 Japanese Unexamined Patent Publication No. 2018-064097

The present invention provides composite fillers for polymer complexes with high voltage output constants. Further, the present invention provides a composite filler for a polymer composite piezoelectric material having both a high piezoelectric constant and a high voltage output constant. Further, the present invention provides a method for producing a composite filler for a polymer composite piezoelectric body having a high piezoelectric constant and a high voltage output constant at low cost.

The present inventors have conducted extensive research to solve the above problems. As a result, the present invention is obtained by using a composite filler containing a specific metal oxide fiber and a specific piezoelectric ceramic particle as a filler for a polymer composite piezoelectric material, and producing the composite filler by a specific method. We have found that the above problems can be solved, and have completed the present invention.

The present invention has the following configurations.
[1] Metal oxide fibers having an average fiber diameter of 0.1 to 10 μm and an aspect ratio of 2 or more, and piezoelectric ceramic particles having an average particle diameter of 0.01 to 200 μm and an aspect ratio of less than 2. Composite filler containing.
[2] The composite filler according to [1], wherein the metal oxide fiber and the piezoelectric ceramic particles are integrated.
[3] The composition of the metal oxide fiber is mainly composed of a titanium acid metal salt, and the composition of the piezoelectric ceramic particles is mainly composed of a titanium acid metal salt or a niobic acid alkali metal salt [1] or [2]. The composite filler described in.
[4] The composite filler according to any one of [1] to [3], wherein the molar ratio of the metal oxide fiber to the piezoelectric ceramic particles is in the range of 1: 0.1 to 1:10.
[5] A resin composition containing the composite filler according to any one of [1] to [4] and a polymer.
[6] The resin composition according to [5], wherein the ratio of the composite filler to the total amount of the composite filler and the polymer is 10 to 90% by volume.
[7] The resin composition according to [5] or [6], further containing 0.1 to 10% by weight of a dispersant and / or 0.1 to 10% by weight of a leveling agent with respect to the composite filler. ..
[8] The resin composition according to any one of [5] to [7], further containing a solvent.
[9] The resin composition according to any one of [5] to [8], which is used for producing a polymer composite piezoelectric body.
[10] A polymer composite piezoelectric body comprising the resin composition according to any one of [5] to [7].
[11] A piezoelectric element provided with a conductive layer on one side or both sides of the polymer composite piezoelectric material according to [10].
[12] A step of preparing a spinning solution containing a metal salt and piezoelectric ceramic particles having an average particle diameter of 0.01 to 200 μm and an aspect ratio of less than 2, and a composite filler precursor by electrostatically spinning the spinning solution. A method for producing a composite filler, which comprises a step of producing a body, a step of firing the composite filler precursor to prepare a composite filler aggregate, and a step of crushing the composite filler aggregate.

By using the composite filler of the present invention as a filler for a polymer composite piezoelectric body, it becomes possible to provide a polymer composite piezoelectric body having a high voltage output constant. Further, it becomes possible to provide a polymer composite piezoelectric body having both a high piezoelectric constant and a high voltage output constant. Further, according to the manufacturing method of the present invention, it is possible to provide a composite filler for a polymer composite piezoelectric body having a high piezoelectric constant and a high voltage output constant at low cost.

It is a scanning electron micrograph of a composite filler according to an embodiment of the present invention. 3 is a scanning electron micrograph (partially enlarged view of FIG. 1) showing an integrated state of barium titanate fibers and barium titanate particles of the composite filler according to the embodiment of the present invention. It is a barium titanate fiber used in the Example of this invention, and is the scanning electron micrograph of the barium titanate fiber as a comparative example. It is a barium titanate particle used in the Example of this invention, and is the scanning electron micrograph of the barium titanate particle as a comparative example.

As used herein, the term "main component" means a component that occupies the largest proportion of the components constituting a certain aggregate. It means that the component is preferably 50% by weight or more, more preferably 85% by weight or more, and further preferably 95% by weight or more.

The composite filler of the present invention comprises a metal oxide fiber having an average fiber diameter of 0.1 to 10 μm and an aspect ratio of 2 or more, and a piezoelectric fiber having an average particle diameter of 0.01 to 200 μm and an aspect ratio of less than 2. It is characterized by containing sex ceramic particles.

<Metal oxide fiber>
The average fiber diameter of the metal oxide fiber used in the present invention is in the range of 0.1 to 10 μm. When the average fiber diameter of the metal oxide fiber is 0.1 μm or more, high piezoelectric characteristics can be obtained when the composite filler is used as a filler for a polymer composite piezoelectric material, and the composite filler can be provided at low cost. Therefore, it is preferable that the thickness is 10 μm or less because the thickness of the polymer composite piezoelectric body can be reduced, so that the flexibility can be increased and the driving voltage can be lowered. From such a viewpoint, the average fiber diameter of the metal oxide fiber is preferably in the range of 0.2 to 5 μm, and more preferably in the range of 0.3 to 2 μm. The method for controlling the average fiber diameter is not particularly limited, but the composition of the spinning solution (type of solvent, concentration of metal salt, molecular weight and concentration of fiber forming material, etc.) in the electrostatic spinning step described later, the viscosity of the spinning solution, and the like. Electrostatic spinning conditions and the like can be mentioned, and the average fiber diameter can be controlled by appropriately changing these.

The aspect ratio of the metal oxide fiber used in the present invention is 2 or more. When the aspect ratio is 2 or more, when the composite filler is used as a filler for the polymer composite piezoelectric body, the polymer composite piezoelectric body having an excellent piezoelectric constant and voltage output constant can be obtained, which is preferable. The upper limit of the aspect ratio of the metal oxide fiber is not particularly limited, but is preferably 1000 or less from the viewpoint of uniform dispersion of the composite filler in the polymer. From such a viewpoint, the aspect ratio of the metal oxide fiber is more preferably in the range of 3 to 100, further preferably in the range of 4 to 50, and particularly preferably in the range of 5 to 20. The aspect ratio of the metal oxide fiber can be calculated as (fiber length) / (fiber diameter) from the fiber length and fiber diameter of the metal oxide fiber measured from, for example, a scanning electron micrograph.

The average fiber length of the metal oxide fiber used in the present invention is not particularly limited, but is preferably in the range of 0.2 to 1000 μm, more preferably in the range of 0.5 to 100 μm, and 1 to 1 to 100 μm. The range of 50 μm is more preferable, and the range of 1.5 to 20 μm is particularly preferable. When the average fiber length is 0.2 μm or more, it is preferable because the piezoelectric constant and the voltage output constant of the polymer composite piezoelectric body can be improved, and when it is 1000 μm or less, it can be uniformly dispersed in the polymer or the like. Therefore, it is preferable. The method for controlling the average fiber length is not particularly limited, but can be controlled by the crushing method in the crushing step described later, the crushing time, and the like.

The composition of the metal oxide fiber used in the present invention is not particularly limited as long as it is an oxide with one component or two or more metal elements. Metallic elements include silicon, aluminum, lithium, sodium, potassium, magnesium, calcium, strontium, barium, yttrium, lantern, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, tungsten, manganese, iron, cobalt, nickel. , Copper, silver, zinc, boron, indium, tin, lead, bismuth can be exemplified. More specifically, the composition of the metal oxide fiber is SiO ₂ , Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, SrO, BaO, Y ₂ O ₃ , La ₂ O. ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , VO, Nb ₂ O ₅ , Ta ₂ O ₅ , Cr ₂ O ₃ , WO ₃ , MnO, FeO, Fe ₃ O ₄ , Fe ₂ O ₃ , CoO, Co ₂ O ₃ , Co ₃ O ₄ , NiO, Ni ₂ O ₃ , CuO, AgO, ZnO, B ₂ O ₃ , In ₂ O ₃ , SnO ₂ , PbO, Bi ₂ O ₃ , or mixtures or composite metal oxides thereof. It can be exemplified. The composition of the metal oxide fiber in the present invention preferably contains a metal titanate as a main component from the viewpoint of improving the piezoelectric constant and the voltage output constant of the polymer composite piezoelectric material containing the composite filler. Examples of the metal barium titanate include calcium titanate, barium titanate, strontium titanate, barium titanate, barium titanate, barium titanate, barium titanate, barium calcium titanate, calcium barium titanate, and barium titanate. Examples thereof include lead, lead zirconate titanate, bismuth titanate, sodium bismuth titanate, bismuth potassium titanate, potassium bismuth sodium titanate, or mixtures and composite metal oxides thereof, among which high piezoelectric constants and voltages are available. In terms of having an output constant, it is more preferable to have barium titanate, barium titanate, barium calcium titanate calcium, bismuth sodium titanate, or bismuth potassium titanate as the main components, and barium titanate as the main component. Is more preferable. When the composition of the metal oxide fiber in the present invention is barium titanate, the molar ratio (Ba / Ti ratio) of barium and titanium is preferably in the range of 0.8 to 1.2, and is preferably 0.9. It is more preferably in the range of ~ 1.1, further preferably in the range of 1.00 to 1.05, and particularly preferably in the range of 1.01 to 1.04. When the Ba / Ti ratio is in the range of 0.8 to 1.2, excellent piezoelectric constants and voltage output constants can be imparted when the composite filler is used as a filler for polymer composite piezoelectric materials. It will be possible.

<Piezoelectric ceramic particles>
The average particle size of the piezoelectric ceramic particles used in the present invention is 0.01 to 200 μm. When the average particle size of the piezoelectric ceramic particles is 0.01 μm or more, a high piezoelectric constant and voltage output constant can be obtained when the composite filler is used as a filler for a polymer composite piezoelectric material, and spinning described later. It is preferable because the piezoelectric ceramic particles are less likely to aggregate in the solution and the composite filler can be stably produced. Further, when the average particle size of the piezoelectric ceramic particles is 200 μm or less, the thickness of the polymer composite piezoelectric body can be reduced, so that the flexibility can be increased, the driving voltage can be lowered, and the spinning solution can be used. This is preferable because the piezoelectric ceramic particles are less likely to precipitate and a composite filler having a uniform molar ratio between the metal oxide fibers and the piezoelectric ceramic particles can be obtained. From this point of view, the average particle size of the piezoelectric ceramic particles is more preferably in the range of 0.05 to 100 μm, further preferably in the range of 0.1 to 30 μm, and 0.5 to 15 μm. It is particularly preferable that the range is.

The aspect ratio of the piezoelectric ceramic particles used in the present invention is less than 2. If the aspect ratio is less than 2, the relative permittivity of the polymer composite piezoelectric material can be reduced, a high voltage output constant can be obtained, and the piezoelectric ceramic particles can be easily manufactured and obtained. It can be obtained at low cost. From this point of view, the aspect ratio of the piezoelectric ceramic particles is preferably 1.8 or less. The aspect ratio of the piezoelectric ceramic particles can be calculated as (longest diameter) / (shortest diameter) from, for example, the longest diameter and the shortest diameter of the piezoelectric ceramic particles measured from a scanning electron micrograph.

The composition of the piezoelectric ceramic particles used in the present invention is not particularly limited as long as it has a piezoelectricity. Here, piezoelectricity is a property in which an electric charge is generated when stress is applied, and conversely, when a voltage is applied, it is deformed. Such a composition is not particularly limited, and is a metal titanate such as barium titanate, lead zirconate titanate, barium calcium titanate zirconate, bismuth sodium titanate, bismuth potassium titanate, or sodium bismuth potassium titanate. Examples thereof include salts, niobate alkali metal salts such as potassium niobate, sodium niobate, lithium niobate, or potassium niobate sodium, bismuth iron acid, zinc oxide, aluminum nitride, or mixtures and composite metal oxides thereof. The composition of the piezoelectric ceramic particles in the present invention may contain a metal barium titanate salt or an alkali metal niobate salt as a main component from the viewpoint of improving the piezoelectric constant and the voltage output constant of the polymer composite piezoelectric material containing the composite filler. It is preferable that the main component is barium titanate, lead zirconate titanate, calcium barium titanate, sodium bismas sodium titanate, potassium bismuth titanate or potassium niobate as a main component, and barium titanate or potassium niobate. It is more preferable to use sodium as a main component.

When the composition of the piezoelectric ceramic particles in the present invention is barium titanate, the molar ratio (Ba / Ti ratio) of barium to titanium is preferably in the range of 0.8 to 1.2, preferably 0.9. It is more preferably in the range of ~ 1.1. When the Ba / Ti ratio is in the range of 0.8 to 1.2, excellent piezoelectric constants and voltage output constants can be imparted when the composite filler is used as a filler for polymer composite piezoelectric materials. It will be possible. The barium titanate particles can be produced, for example, by mixing barium carbonate and titanium oxide and reacting them by calcining, and commercially available ones can also be used.

When the composition of the piezoelectric ceramic particles in the present invention is sodium potassium niobate, the molar ratio (Na / K ratio) of sodium and potassium is preferably in the range of 1.0 to 1.5. More preferably, it is in the range of 10 to 1.25. The ratio of the total number of moles of sodium and potassium to the number of moles of niobium ((Na + K) / Nb ratio) is preferably in the range of 0.9 to 1.1, preferably 0.95 to 1.05. It is more preferably in the range. When the Na / K ratio and the (Na + K) / Nb ratio are in the above ranges, excellent piezoelectric constants and voltage output constants can be imparted when the composite filler is used as a filler for a polymer composite piezoelectric body. It will be possible. The sodium niobate particles can be produced, for example, by mixing sodium carbonate, potassium carbonate and niobium oxide and reacting them by calcining, and commercially available ones can also be used.

<Composite filler>
The composite filler of the present invention contains the above-mentioned metal oxide fibers and piezoelectric ceramic particles. By including the metal oxide fiber and the piezoelectric ceramic particles, the polymer composite piezoelectric material containing the composite filler has an excellent balance between the piezoelectric constant and the relative permittivity, and can have a high voltage output constant. Such properties have not been predicted in the prior art and are novel effects found in the present invention. In the present invention, the metal oxide fiber and the piezoelectric ceramic particles may be integrated or may be simply mixed without being integrated, but from the viewpoint of achieving both a high piezoelectric constant and a high voltage output constant. Therefore, it is preferable that they are integrated. The integration in the present invention is a state in which the metal oxide fiber and the piezoelectric ceramic particles are bonded without a gap, and a state in which the piezoelectric ceramic particles are completely contained in the metal oxide fiber. Examples thereof include a state in which a part of the piezoelectric ceramic particles is partially embedded in the metal oxide fiber, or a state in which the surface of the metal oxide fiber and the surface of the piezoelectric ceramic particles are fused. Without being bound by any particular theory, the integration of the metal oxide fibers with the piezoelectric ceramic particles allows the charge or deformation generated by the piezoelectric ceramic particles to be applied to the entire composite filler without attenuation. It is thought that it can be transmitted.

The relationship between the average fiber diameter of the metal oxide fiber of the composite filler and the average particle diameter of the piezoelectric ceramic particles is not particularly limited, but the average fiber diameter of the metal oxide fiber / the average particle diameter of the piezoelectric ceramic particles is 0. It is preferably in the range of 01 to 100, more preferably in the range of 0.05 to 10, and even more preferably in the range of 0.1 to 5. If the average fiber diameter of the metal oxide fiber / the average particle size of the piezoelectric ceramic particles is 0.01 or more, the piezoelectric ceramic particles do not become too large with respect to the metal oxide fiber, and the thickness of the polymer composite piezoelectric body. It is preferable because the piezoelectric ceramic particles are less likely to precipitate in the spinning solution, and if it is 100 or less, the piezoelectric ceramic particles do not become too small with respect to the metal oxide fiber, and the piezoelectric ceramic particles have high piezoelectricity. It is preferable because a polymer composite piezoelectric body having a constant value or a constant voltage output can be obtained, and the piezoelectric ceramic particles are less likely to aggregate in the spinning solution.

The molar ratio of the metal oxide fiber of the composite filler to the piezoelectric ceramic particles is not particularly limited, but is preferably in the range of 1: 0.1 to 1:10, and is preferably 1: 0.5 to 1: 5. It is more preferably in the range of 1: 1 to 1: 3, and even more preferably in the range of 1: 1 to 1: 3. When the molar ratio of the metal oxide fiber to the piezoelectric ceramic particles is 1: 0.1 or more, the relative permittivity of the polymer composite piezoelectric material can be reduced, a high voltage output constant can be obtained, and the composite filler can be obtained. It is preferable because it can increase the yield of It is preferable because it can be produced uniformly and uniformly.

The composition of the metal oxide fiber and the composition of the piezoelectric ceramic particles in the composite filler may be the same or different. The combination of the composition of the metal oxide fiber and the composition of the piezoelectric ceramic particles is not particularly limited, and is not particularly limited. Barium titanate and barium titanate, lead zirconate titanate and lead zirconate titanate, barium titanate and lead zirconate titanate. Lead Acid, Barium Titanate and Barium Titanate, Sodium Titanate and Barium Titanate, Barium Titanate Potassium and Barium Titanate, Barium Titanate and Sodium Niobate, Sodium Bismus Sodium Titanium and Sodium Niobate Can be exemplified.

When the combination of the composition of the metal oxide fiber and the composition of the piezoelectric ceramic particles in the composite filler is, for example, barium titanate and barium titanate, the crystal structure thereof is the ratio of the c-axis to the a-axis in the crystal lattice (c). / A ratio) is preferably 1.005 or more, more preferably 1.008 or more, and even more preferably 1.010 or more. When the c / a ratio is 1.005 or more, when the composite filler is used as a filler for the polymer composite piezoelectric body, it is possible to impart an excellent piezoelectric constant or voltage output constant. The crystallite size of the composite filler is not particularly limited, but is preferably 20 nm or more, and more preferably 25 nm or more. When the crystallite size of the composite filler is 20 nm or more, it is possible to impart more excellent piezoelectric characteristics when used as a filler for a polymer composite piezoelectric body. The method for controlling the c / a ratio and the crystallite size of the composite filler is not particularly limited, but examples thereof include changing the firing temperature, firing time, and heating rate in the firing step described later, and the size thereof is X. It can be calculated from the measurement result by the linear diffraction method.

The composite filler of the present invention is not particularly limited, and may be surface-treated with a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, a zirconium coupling agent, a zircoaluminate coupling agent, or the like. The functional group at the end of the coupling agent is not particularly limited, and examples thereof include alkyl, phenyl, amino, fluoro, acryloyl, epoxy, ureido, and acid anhydride, which can be appropriately selected depending on the properties of the material to be complexed.

<Manufacturing method of composite filler>
The method for producing the composite filler of the present invention is not particularly limited, and is a method of processing a solution, a melt, a slurry or the like containing a raw material of the composite filler into a specific shape and then synthesizing the composite filler, or processing and synthesizing at the same time. An example of how to do this can be illustrated. Among them, the method of synthesizing the composite filler after processing the raw material into a specific shape is preferable because it is easy to control the shape, composition, crystallinity, molar ratio of the metal oxide fiber and the piezoelectric ceramic particles, and the like. The processing method is not particularly limited, and is a mold forming method, a casting method, a doctor blade method, an extrusion molding method, a dry spinning method, a wet spinning method, a melt spinning method, a spunbond method, a melt blown method, a rotary spinning method, or a static spinning method. The electrospinning method can be exemplified. Among them, the electrostatic spinning method is preferable because the average fiber diameter of the metal oxide fiber of the composite filler can be reduced and it can be uniformly dispersed even in a polymer composite piezoelectric material such as a thin film. Further, the synthesis method is not particularly limited, and examples thereof include a firing method, a light heating method, a discharge plasma sintering method, and a hydrothermal synthesis method.

Hereinafter, a method for producing a composite filler using an electrostatic spinning method will be described, but the present invention is not limited thereto.

The method for producing the composite filler using the electrostatic spinning method is not particularly limited, and the step of preparing a spinning solution containing a metal salt and specific piezoelectric ceramic particles and the composite filler by electrostatically spinning the spinning solution. An example can be exemplified of a method including a step of producing a precursor, a step of firing the composite filler precursor to prepare a composite filler aggregate, and a step of crushing the composite filler aggregate.

<Spinning solution preparation process>
The spinning solution in the present invention is not particularly limited as long as it contains a metal salt and specific piezoelectric ceramic particles, and a state in which the metal salt and the piezoelectric ceramic particles are dispersed in a solvent, the metal salt and the piezoelectric ceramic particles can be used. Examples thereof include a state in which the metal salt is dissolved in the solvent and a state in which the piezoelectric ceramic particles are dispersed in the solvent. Among them, from the viewpoint of facilitating the processing of the composite filler into a specific shape, it is preferable to use a spinning solution in which the metal salt is dissolved in the solvent and the piezoelectric ceramic particles are dispersed in the solvent. The method for obtaining such a spinning solution is not particularly limited, and is a method of blending piezoelectric ceramic particles in a solution in which a metal salt is dissolved, or a method in which a metal salt is blended and dissolved in a solution in which the piezoelectric ceramic particles are dispersed. An example thereof is a method of allowing the metal salt to be dissolved, or a method of mixing a solution in which the metal salt is dissolved and a solution in which the piezoelectric ceramic particles are dispersed. The mixing method is not particularly limited, and can be performed using known equipment such as a magnetic stirrer, a shaker, a planetary stirrer, or an ultrasonic device.

The metal salt used for producing the composite filler of the present invention is not particularly limited, and is silicon, aluminum, lithium, sodium, potassium, magnesium, calcium, strontium, barium, ittrium, lanthanum, titanium, zirconium, hafnium, vanadium, and niobium. , Tantal, Chromium, Tungsten, Manganese, Iron, Cobalt, Nickel, Copper, Silver, Zinc, Boron, Indium, Tin, Lead, Bismus and other metal elements such as acetates, carbonates, nitrates, oxalates, sulfates, Hydroxides, halides, or alkoxides can be exemplified. As the metal salt used for producing the composite filler, a metal salt having a desired composition may be appropriately selected, and the metal salt may be used alone or in combination of two or more.

The solvent used for producing the composite filler of the present invention is not particularly limited, and water, methanol, ethanol, propanol, ethylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, toluene, xylene, pyridine, tetrahydrofuran, dichloromethane, chloroform, 1,1,1,3,3,3-hexafluoroisopropanol, formic acid, acetic acid, or propion An acid can be exemplified. As the solvent used for producing the composite filler, a solvent capable of uniformly dispersing or dissolving the metal salt and the piezoelectric ceramic particles may be appropriately selected, and these may be used alone or in combination of two or more. good.

The spinning solution in the present invention may contain a fiber-forming material for the purpose of imparting spinnability. The fiber-forming material is not particularly limited, and is not particularly limited. Polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, polyethylene, polypropylene, polyethylene terephthalate, polylactic acid, polyamide, polyurethane, polystyrene, polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate. , Polyglycolic acid, polycaprolactone, cellulose, cellulose derivatives, chitin, chitosan, collagen, or copolymers or mixtures thereof. The weight average molecular weight of the fiber-forming material is not particularly limited, but is preferably in the range of 10,000 to 10,000,000, more preferably in the range of 50,000 to 5,000,000. It is more preferably 100,000 to 1,000,000. When the weight average molecular weight is 10,000 or more, it is preferable because it is excellent in fiber forming property, and when it is 10,000,000 or less, it is preferable because it is excellent in solubility and the preparation process is simplified.

The spinning solution in the present invention may contain a conductive auxiliary agent for the purpose of improving fiber forming property. The conductive auxiliary agent can be used as long as it does not impair the uniformity and spinning stability of the spinning solution, and examples thereof include sodium dodecyl sulfate, tetrabutylammonium bromide, and ammonium acetate. It is preferable that the conductive auxiliary agent has a property of completely disappearing in the firing step, such as not containing metal ions, in that a composite filler having a desired composition can be obtained. The concentration of the conductive auxiliary agent is not particularly limited, but is preferably in the range of 0.001 to 1% by weight, preferably in the range of 0.01 to 0.1% by weight, based on the weight of the spinning solution. More preferred. When the concentration of the conductive auxiliary agent is 0.001% by weight or more, the effect suitable for use can be improved, and when it is 1% by weight or less, a composite filler having a desired composition can be obtained, which is preferable. The spinning solution also contains stabilizers having polydentate ligands such as ethylenediamine, ethylenediaminetetraacetic acid, acetylacetone, citric acid and malic acid for the purpose of improving the stability of metal salts and piezoelectric ceramic particles. May be good. Further, a component other than the above may be contained as a component of the spinning solution as long as the effect of the present invention is not significantly impaired, and a viscosity regulator, a pH adjuster, a preservative, a surfactant and the like may be included.

The viscosity of the spinning solution is preferably adjusted in the range of 5 to 10,000 cP, more preferably in the range of 10 to 8,000 cP, and even more preferably in the range of 100 to 2,000 cP. When the viscosity is 5 cP or more, the spinnability for forming the fiber is obtained, and when the viscosity is 10,000 cP or less, the spinning solution can be easily discharged. A viscosity in the range of 10 to 8,000 cP is more preferable because good spinnability can be obtained in a wide range of spinning conditions, and a viscosity in the range of 100 to 2,000 cP is excellent in a very wide range of spinning conditions. It is more preferable because the spinnability can be obtained. The viscosity of the spinning solution can be adjusted by appropriately changing the concentration of the metal salt or the piezoelectric ceramic particles, the molecular weight of the fiber-forming material, the concentration, the thickener, or the like.

When the composition of the metal oxide fiber in the present invention is barium titanate, a spinning solution in which a barium salt, a titanium alkoxide, and a fiber-forming material are dissolved in a solvent and piezoelectric ceramic particles are dispersed can be preferably used. The molar ratio of the barium salt to the titanium alkoxide in the spinning solution is not particularly limited, but is preferably in the range of 0.8 to 1.2, and more preferably in the range of 0.9 to 1.1. , 1.00 to 1.05 is more preferable, and 1.01 to 1.04 is particularly preferable. When the molar ratio of barium salt to titanium alkoxide is in the range of 0.8 to 1.2, excellent piezoelectric constants and voltage output constants can be obtained when the composite filler is used as a filler for polymer composite piezoelectrics. It becomes possible to grant. The molar ratio of the barium salt to the piezoelectric ceramic particles is not particularly limited, but is preferably in the range of 1: 0.1 to 1:10, and is preferably in the range of 1: 0.5 to 1: 5. It is more preferably in the range of 1: 1 to 1: 3. When the molar ratio of the barium salt to the piezoelectric ceramic particles is 1: 0.1 or more, the relative permittivity of the polymer composite piezoelectric material can be reduced, a high voltage output constant can be obtained, and the yield of the composite filler can be increased. It is preferable because it can be increased, and if it is 1:10 or less, the piezoelectric constant of the polymer composite piezoelectric body can be increased, it is possible to have both a high piezoelectric constant and a high voltage output constant, and the composite filler can be stably and uniformly. It is preferable because it can be manufactured in the same manner. The barium salt is not particularly limited, and examples thereof include barium carbonate, barium acetate, barium hydroxide, barium oxalate, barium nitrate, barium chloride, or a mixture thereof. From the viewpoint of solubility in a solvent, barium carbonate, It is preferably barium acetate or barium nitrate. The titanium alkoxide is not particularly limited, and examples thereof include titanium tetramethoxyd, titanium tetraethoxydo, titanium tetranormal propoxide, titanium tetraisopropoxide, titanium tetranormal butoxide, or a mixture thereof, and the stability of the spinning solution can be exemplified. In addition, titanium tetraisopropoxide or titanium tetranormalbutoxide is preferable because of its availability. The fiber-forming material is preferably polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, or polyacrylic acid, preferably polyvinylpyrrolidone, from the viewpoint of solubility in a solvent and degradability in a baking step. More preferred. As the solvent, it is preferable to use a mixed solvent of an organic acid and an alcohol solvent as a main component from the viewpoint of the solubility of the barium salt, the titanium alkoxide, and the fiber-forming material and the dispersibility of the piezoelectric ceramic particles. The organic acid is not particularly limited, but is preferably formic acid, acetic acid, or propionic acid, and more preferably acetic acid, from the viewpoint of solubility and dispersibility. The alcohol solvent is not particularly limited, but is preferably ethanol, ethylene glycol, ethylene glycol monomethyl ether, or propylene glycol monomethyl ether, and more preferably propylene glycol monomethyl ether, from the viewpoint of solubility and dispersibility. preferable.

<Electrostatic spinning process>
The electrostatic spinning method is a method in which a spinning solution is discharged and an electric field is applied to fiberize the discharged spinning solution and deposit a fiber aggregate on a collector. The electrostatic spinning method includes a method of extruding a spinning solution from a nozzle and applying an electric field to spin the spinning solution, a method of bubbling the spinning solution and applying an electric field to spin the spinning solution, or spinning on the surface of a cylindrical or wire-shaped electrode. An example of a method of spinning by guiding a solution and applying an electric field can be illustrated. According to this method, uniform fibers having a diameter of 10 nm to 10 μm can be obtained.

As a method of discharging the spinning solution, a method of discharging the spinning solution filled in the syringe into the syringe by using a pump can be exemplified. The temperature of the spinning solution at the time of spinning may be normal temperature, high temperature by heating, or low temperature by cooling. The inner diameter of the nozzle is not particularly limited, but is preferably in the range of 0.1 to 1.5 mm. The discharge amount is not particularly limited, but is preferably 0.1 to 10 mL / hr. When the discharge amount is 0.1 mL / hr or more, the composite filler can be produced at low cost, which is preferable, and when the discharge rate is 10 mL / hr or less, a uniform composite filler can be obtained, which is preferable. The polarity of the applied voltage may be positive or negative. Further, the magnitude of the voltage is not particularly limited as long as it can be molded into a specific shape as a composite filler, and in the case of a positive voltage, a range of 5 to 100 kV can be exemplified. The method of applying an electric field is not particularly limited as long as an electric field can be formed in the nozzle and collector, and a method of applying a high voltage to the nozzle to ground the collector, a method of applying a high voltage to the collector to ground the nozzle, and a method of grounding the nozzle. Alternatively, a method of applying a positive high voltage to the nozzle and applying a negative high voltage to the collector can be exemplified. Further, the distance between the nozzle and the collector is not particularly limited as long as the composite filler can be processed into a specific shape, and a range of 5 to 50 cm can be exemplified. The collector may be any as long as it can collect the spun composite filler precursor, and its material and shape are not particularly limited. As the material of the collector, a conductive material such as metal is preferably used. The shape of the collector is not particularly limited, and examples thereof include a flat plate shape, a shaft shape, and a conveyor shape. If the collector is flat, the composite filler precursor can be collected in a sheet shape, if it is a shaft shape, the composite filler precursor can be collected in a tube shape, and if it is a conveyor shape, it can be collected. The composite filler precursor collected in the form of a sheet can be continuously produced.

The electrostatically spun composite filler precursor undergoes a synthesis process such as firing, and the fiber-forming material contained in the precursor is thermally decomposed to contain high-quality metal oxide fibers and piezoelectric ceramic particles. And it forms a highly crystalline composite filler aggregate. A general electric furnace can be used for firing. The firing atmosphere is not particularly limited and can be carried out in an air atmosphere or an inert gas atmosphere, but from the viewpoint of reducing residues such as fiber-forming materials and obtaining a composite filler aggregate having a desired composition. It is preferable to fire in an air atmosphere. The firing method may be one-step firing or multi-step firing. The firing temperature is not particularly limited, but is preferably in the range of 700 to 1500 ° C, more preferably in the range of 800 to 1400 ° C, and particularly preferably in the range of 900 to 1300 ° C. When the firing temperature is 700 ° C. or higher, the residue such as the fiber forming material is reduced, the crystallinity of the composite filler is improved, and the piezoelectric constant and the voltage output constant of the polymer composite piezoelectric body can be improved. Further, when the temperature is 1500 ° C. or lower, the change in composition due to the volatilization of volatile atoms can be reduced, and the energy consumption can be suppressed to a low level. When the firing temperature is in the range of 800 to 1400 ° C., particularly 900 to 1300 ° C., the purity and crystallinity are sufficiently high, and the manufacturing cost can be sufficiently lowered. The firing time is not particularly limited, and a range of 1 to 24 hours can be exemplified. The rate of temperature rise is not particularly limited, and a range of 1 to 200 ° C./min can be exemplified. Further, by molding the electrostatically spun composite filler precursor into an arbitrary shape and firing it, composite filler aggregates having various shapes can be obtained. For example, a sheet-shaped composite filler aggregate can be obtained by molding and firing in a two-dimensional sheet shape, and a tube-shaped composite filler aggregate can be obtained by winding it around a shaft and collecting it. can. It is also possible to obtain a cotton-like composite filler aggregate by collecting it in a liquid, freeze-drying it, forming it into a cotton-like shape, and firing it.

The calcined composite filler aggregate is further refined by pulverization or the like to obtain a composite filler in order to facilitate filling in the polymer matrix. The method of crushing is not particularly limited, and examples thereof include ball mills, bead mills, jet mills, high-pressure homogenizers, planetary mills, rotary crushers, hammer crushers, cutter mills, stone mills, mortars, and screen mesh crushers, even if they are dry. Although it may be wet, screen mesh grinding is preferably used because the composite filler can be controlled to a specific shape. Screen mesh crushing is a method of placing a composite filler aggregate on a mesh with a predetermined opening and filtering it with a brush or spatula, or a composite filler aggregate with beads such as alumina, zirconia, glass, PTFE, nylon, or polyethylene. An example of a method of applying vertical and / or horizontal vibration by placing and on a mesh can be illustrated. The mesh opening used is not particularly limited, but is preferably in the range of 20 to 1000 μm, and more preferably in the range of 50 to 500 μm. When the opening is 20 μm or more, it is preferable because the pulverization treatment time can be shortened, and when it is 1000 μm or less, coarse substances and aggregates of the composite filler can be removed, which is preferable. The pulverization method and conditions may be appropriately changed for the required characteristics.

<Resin composition>
The resin composition of the present invention contains a composite filler and a polymer. The polymer used in the present invention is not particularly limited as long as it has excellent dispersibility of the composite filler as a matrix of the polymer composite piezoelectric material and can impart flexibility to the polymer composite piezoelectric body, and is not particularly limited. It may be a plastic polymer, a thermosetting polymer, or a photocurable polymer. Examples of the thermoplastic polymer include polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, a copolymer of vinylidene fluoride and trifluoroethylene, or a copolymer of vinylidene fluoride and tetrafluoroethylene. Vinylidene fluoride polymers such as polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, polyethylene, polypropylene, polyethylene terephthalate, polylactic acid, polyamide, polyurethane, polystyrene, cyanoethylated polyvinyl alcohol, cyanoethylated purulan, cyanoethylated cellulose, etc. Examples thereof include polyacrylonitrile, polymethylmethacrylate, polyglycolic acid, polycaprolactone, polyvinylformal, polyvinylbutyral, polysulfone, polyethersulfone, cellulose, cellulose derivatives, chitin, chitosan, collagen, or copolymers and mixtures thereof. Examples of the thermosetting polymer include epoxy compounds, oxetane compounds, phenol resins, polyimide resins, (meth) acrylic resins having crosslinkable functional groups, and copolymers and mixtures thereof. As the photocurable polymer, an acrylate-based photocurable resin (for example, urethane acrylate, polyester acrylate, etc.) or an epoxy-based photocurable resin can be exemplified, and a known photoinitiator can be used. Among these, vinylidene fluoride-based polymers are preferable from the viewpoint of imparting excellent flexibility, insulating properties, and piezoelectric properties to the polymer composite piezoelectric body, and polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene is preferable. It is more preferably a polymer, and even more preferably a copolymer of vinylidene fluoride and hexafluoropropylene. The polymer itself may or may not have piezoelectricity, but the use of a polymer having no piezoelectricity causes the piezoelectricity to cancel each other out with the composite filler. It is preferable because a polymer composite having a high piezoelectric constant and voltage output constant can be obtained without any problem. On the other hand, by using a polymer having pyroelectricity by itself, it is possible to obtain a high pyroelectric constant by the synergistic effect with the pyroelectric effect of the composite filler. Further, by using an elastomer as the polymer, it is possible to obtain a polymer composite piezoelectric body having excellent elasticity. Such an elastomer is not particularly limited, and is preferably an elastomer having high elasticity, and examples thereof include silicon-based elastomers, acrylic-based elastomers, fluoroelastomers, amide-based elastomers, ester-based elastomers, and olefin-based elastomers.

The weight average molecular weight of the polymer used in the present invention is not particularly limited, but is preferably in the range of 10,000 to 10,000,000, and preferably in the range of 50,000 to 5,000,000. It is more preferably 100,000 to 1,000,000. A weight average molecular weight of 10,000 or more is preferable because the mechanical properties and handleability of the polymer composite piezoelectric body are improved, and a weight average molecular weight of 10,000 or less is excellent in solubility and thermoplasticity, and processing is possible. It is preferable because it is easy.

In the resin composition of the present invention, the ratio of the composite filler to the total amount of the composite filler and the polymer is not particularly limited, but is preferably in the range of 10 to 90% by volume, preferably in the range of 50 to 85% by volume. It is more preferably in the range of 60 to 80% by volume. When the ratio of the composite filler to the total amount of the composite filler and the polymer is 10% by volume or more, it is preferable because a polymer composite piezoelectric material having an excellent piezoelectric constant and voltage output constant can be obtained, and when it is 90% by volume or less. This is preferable because a polymer composite piezoelectric body having excellent flexibility can be obtained. Here, the flexibility can be evaluated by, for example, the presence or absence of cracks or the like when a bending test is performed at a bending angle of 180 ° and a bending radius of 30 mm.

The resin composition of the present invention is not particularly limited, but may contain a dispersant as a component other than the polymer and the composite filler. The dispersant is not particularly limited as long as it can uniformly disperse the composite filler in the polymer matrix, and may be a small molecule dispersant or a polymer dispersant. Low molecular weight dispersants include anionic surfactants such as sodium dodecyl sulfate, cationic surfactants such as tetrabutylammonium bromide, and nonionic surfactants such as polyoxyethylene sorbitamon monolaurate. Can be exemplified. As the polymer dispersant, for example, a nonionic type, a cationic type, or an anion type can be selected. Among these polymer dispersants, those having an amine value and an acid value are preferable, and specifically, those having an amine value in terms of solid content of 5 to 200 and an acid value of 1 to 100 are preferable. Examples are "Solspur" (manufactured by Lubrizol) 24000, "EFKA" (manufactured by Ciba Specialty Chemicals) 4046, "Ajinomoto Fine Techno" (manufactured by Ajinomoto Fine Techno) PB821, "BYK" (manufactured by Big Chemie) 160. Etc. can be preferably used. The content of the dispersant is not particularly limited, but is preferably in the range of 0.1 to 10% by weight, more preferably in the range of 0.2 to 5% by weight, based on the composite filler. It is more preferably in the range of 0.5 to 3% by weight. When the content of the dispersant is 0.1% by weight or more with respect to the composite filler, the composite filler can be uniformly dispersed in the polymer, and a high piezoelectric constant and voltage output constant can be obtained, which is preferable. When it is 10% by weight or less, it is preferable because the characteristics of the polymer and the composite filler can be maintained without being impaired.

The resin composition of the present invention is not particularly limited, but may contain a leveling agent as a component other than the polymer and the composite filler. The leveling agent is not particularly limited as long as it can improve surface defects such as unevenness and flipping of the coating film when the liquid resin composition described later is applied to the support, and is not particularly limited. However, it may be a polymer leveling agent. Examples of the small molecule leveling agent include "BYK" (manufactured by DIC Chemie) 361N, and "Surflon (manufactured by AGC Seimi Chemical) S-232". Examples of the polymer leveling agent include "BYK" (manufactured by DIC Chemie) 354. "Megafuck" (manufactured by DIC Corporation) F-563 can be exemplified. The content of the leveling agent is not particularly limited, but is preferably in the range of 0.1 to 10% by weight with respect to the composite filler. It is more preferably in the range of 0.2 to 5% by weight, further preferably in the range of 0.5 to 3% by weight. The content of the leveling agent is 0.1% by weight or more with respect to the composite filler. If this is the case, it is possible to improve the surface defects of the coating film, and a high piezoelectric constant and voltage output constant can be obtained. Therefore, if it is 10% by weight or less, the characteristics of the polymer and the composite filler can be maintained without being impaired. Therefore, the leveling agent may be used in combination with the dispersant, or may use only the leveling agent without using the dispersant.

The resin composition of the present invention is not particularly limited, but may further contain a solvent. The solvent used in the resin composition is not particularly limited as long as it can uniformly disperse or dissolve the composite filler, polymer, and other additives, and is not particularly limited, and is limited to water, methanol, ethanol, propanol, acetone, methyl ethyl ketone, and methyl isobutyl. Ketone, cyclohexanone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylpropionamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, ethyl acetate, butyl acetate, propylene carbonate, diethylene carbonate, toluene , Xylene, pyridine, tetrahydrofuran, dichloromethane, chloroform, 1,1,1,3,3,3-hexafluoroisopropanol, triethyl phosphate, formic acid, acetic acid, or a mixed solvent thereof can be exemplified. When a vinylidene fluoride polymer is used as the polymer, the solvent used is N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylpropionamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone. , Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, triethyl phosphate, or a mixed solvent thereof is preferably used.

The concentration of the solvent in the resin composition of the present invention is not particularly limited as long as it can be uniformly applied to produce the polymer composite piezoelectric body, but is preferably in the range of 5 to 95% by weight, preferably 20 to 90. It is more preferably in the range of% by weight, further preferably in the range of 30-80% by weight.

The viscosity of the resin composition of the present invention is not particularly limited, and it is preferable to adjust the viscosity so that it is in the range of 1 to 100,000 cP because the workability of the coating process can be improved, and it is preferably in the range of 5 to 5000 cP. It is more preferably in the range of 10 to 2000 cP. In particular, in the case of a resin composition for screen printing, the range is preferably in the range of 100 to 50,000 cP.

Depending on the desired properties, the resin composition of the present invention may contain additives other than the dispersant or the leveling agent as long as the effects of the present invention are not impaired. Examples of such additives include polymer compounds, epoxy compounds, acrylic resins, inorganic particles, metal particles, surfactants, antistatic agents, viscosity modifiers, thixophilic adjusters, adhesion improvers, epoxy hardeners, and the like. Examples thereof include rust preventives, preservatives, fungicides, antioxidants, antioxidants, evaporation promoters, chelating agents, pigments, titanium blacks, carbon blacks, or dyes. These additives may be used alone or in combination of two or more, depending on the desired characteristics.

The resin composition of the present invention may be in the form of a powder (for example, a powder mixture obtained by mixing a polymer and a composite filler, optionally a dispersant, and / or a leveling agent) in the form of pellets (for example, a mixture of a polymer and a composite filler, and / or a leveling agent). For example, it may be a pellet formed by kneading a polymer and a composite filler, optionally a dispersant, and / or a leveling agent, and may be in a liquid form such as a solution / dispersion (for example, a polymer and a composite filler). It may be a liquid composition such as a coating composition, an ink, a varnish, etc., which contains a solvent and optionally a dispersant and / or a leveling agent. The resin composition of the present invention can be used for producing a polymer composite piezoelectric body.

<Polymer composite piezoelectric body>
Since the polymer composite piezoelectric material of the present invention is produced from the resin composition containing the above-mentioned composite filler and polymer, it has a high piezoelectric constant, a voltage output constant, and excellent flexibility. Examples of the shape of the polymer composite piezoelectric body include a film, fiber, non-woven fabric, or block shape, but a film shape is preferable.

The thickness of the polymer composite piezoelectric body of the present invention is not particularly limited, but is preferably in the range of 5 to 500 μm, more preferably in the range of 10 to 200 μm, and more preferably in the range of 20 to 100 μm. More preferred. When the thickness of the polymer composite piezoelectric body is 5 μm or more, it is preferable because the mechanical strength can be maintained, and when it is 500 μm or less, it is preferable because it is excellent in flexibility and the driving voltage can be lowered.

The breaking elongation of the polymer composite piezoelectric material of the present invention is not particularly limited, but is preferably 10% or more, more preferably 30% or more, still more preferably 100% or more. When the elongation at break is 10% or more, it is preferable because it can be easily processed into an arbitrary shape and can be applied to applications accompanied by large deformation.

The elastic modulus of the polymer composite piezoelectric material of the present invention is not particularly limited, and may be adjusted to an elastic modulus suitable for the intended use. In applications that require high generating force, such as tactile devices and electroacoustic conversion devices, the elastic modulus is preferably 1000 MPa or more, more preferably 3000 MPa or more, and even more preferably 5000 MPa or more. On the other hand, in applications such as wearable devices where elasticity and flexibility are required, the elastic modulus is preferably less than 1000 MPa, preferably less than 500 MPa, and even more preferably less than 100 MPa. The range of elastic modulus that can be applied to various uses is not particularly limited, but is preferably in the range of 100 to 10000 MPa, more preferably in the range of 200 to 5000 MPa, and preferably in the range of 500 to 3000 MPa. More preferred.

The melting temperature or softening temperature of the polymer composite piezoelectric material of the present invention is not particularly limited, but is preferably 60 ° C. or higher, more preferably 80 ° C. or higher, still more preferably 100 ° C. or higher. .. When the melting temperature or the softening temperature is 60 ° C. or higher, the heat resistance of the polymer composite piezoelectric body can be improved, and it can be used in a high temperature environment.

The relative permittivity of the polymer composite piezoelectric material of the present invention is not particularly limited, and may be adjusted to a relative permittivity suitable for the intended use. In the case of applications that utilize the property of converting electrical energy into mechanical energy (reverse piezoelectric effect) such as electroacoustic conversion equipment, actuators, and tactile devices, the relative permittivity is preferably 10 or more, and preferably 20 or more. More preferably, it is more preferably 50 or more. When the relative permittivity of the polymer composite piezoelectric body is 10 or more, it is possible to obtain a large deformation when a voltage is applied. On the other hand, in the case of applications that utilize the property of converting mechanical energy into electrical energy (positive piezoelectric effect) such as sensors and power generation devices, the relative permittivity is preferably 60 or less, more preferably 50 or less. It is more preferably 40 or less. When the relative permittivity of the polymer composite piezoelectric body is 60 or less, the voltage output constant can be increased, and a high voltage output can be obtained when a constant pressure is applied.

The piezoelectric constant d ₃₃ of the polymer composite piezoelectric material of the present invention is not particularly limited, but is preferably 60 pC / N or more, more preferably 80 pC / N or more, and further preferably 100 pC / N or more. preferable. If the piezoelectric constant d ₃₃ is 60 pC / N or more, it can be applied to a wide range of fields such as actuators and sensors. The voltage output constant g ₃₃ of the polymer composite piezoelectric body is not particularly limited, but is preferably 180 mVm / N or more, more preferably 240 mVm / N or more, and more preferably 300 mVm / N or more. More preferred. When g ₃₃ is 180 mVm / N or more, the sensitivity as a sensor can be improved, which is preferable. The power generation performance index of the polymer composite piezoelectric material is not particularly limited, but is preferably 15.0 × 10 ^-15 VCm / N ² or more, and 20.0 × 10 ^-15 VCm / N ² or more. It is more preferably 50.0 × 10 ^-15 VCm / N ² or more. When the power generation performance index is 15.0 × 10 ^-15 VCm / N ² , it is preferable because the power generation performance as a power generation device can be improved.

The polymer composite piezoelectric material of the present invention has a high voltage output constant, or a high piezoelectric constant and a high voltage output constant, and is an electroacoustic conversion device such as a speaker or a buzzer, an actuator, a display, a wearable device, a tactile device, and the like. It can be suitably used as a sensor, a power generation device, or the like.

<Manufacturing method of polymer composite piezoelectric body>
The polymer composite piezoelectric body of the present invention can be produced by molding the above-mentioned resin composition into an arbitrary shape and then subjecting it to a polling treatment. The method for molding the resin composition is not particularly limited, and may be a melting method using the powdery or pelletized resin composition of the present invention or a solution method using a liquid resin composition. good. In the case of the melting method, it is preferable that a polymer composite piezoelectric body can be obtained by hot melting without using a solvent. In the case of the solution method, it is preferable that the obtained polymer composite piezoelectric body is excellent in uniformity. Examples of the shape of the polymer composite piezoelectric body include a film, fiber, non-woven fabric, or block shape, but a film shape is preferable. Hereinafter, a method for producing a polymer composite piezoelectric material in the form of a film will be described, but the present invention is not limited thereto.

Examples of the method for producing the polymer composite piezoelectric body by the solution method include a method in which a liquid resin composition is cast and dried. The resin composition of the present invention used in the solution method further contains a solvent in addition to the above-mentioned polymer, composite filler (optionally a dispersant and / or leveling agent). As the solvent, the solvent used in the resin composition can be used at the above-mentioned concentration. The method for preparing the liquid resin composition is not particularly limited, and can be carried out using known equipment such as a magnetic stirrer, a shaker, a ball mill, a jet mill, a planetary stirrer, or an ultrasonic device. The preparation conditions are not particularly limited, and for example, the preparation can be carried out at 10 to 120 ° C. for 1 to 24 hours. The method of applying the liquid resin composition to form a film is not particularly limited, and the spin coating method, the spray coating method, the roll coating method, the slit coating method, the gravure coating method, the cast coating method and the like are used. This can be done using a known method. When patterning is required to produce a piezoelectric element or the like, a known method such as an inkjet method, a screen printing method, or a flexographic printing method can be used. The support to which the liquid resin composition is applied is not particularly limited, and a glass substrate, an aluminum substrate, a copper substrate, a silicon substrate, a polymer film substrate, or the like can be used. The polymer composite piezoelectric material may be left as a film on the support, or a support whose surface has been mold-released may be used in order to form a self-supporting film. The method for drying the solvent is not particularly limited, and a known method such as induction heating, hot air circulation heating, vacuum drying, infrared rays, or microwave heating can be used. As the drying conditions, for example, it can be carried out at 40 to 150 ° C. for 1 to 180 minutes. The dried resin composition can be further subjected to heat pressing or heat treatment for the purpose of promoting uniformity and crystallization. The hot press conditions are not particularly limited, and examples thereof include a press temperature of 60 to 250 ° C., a press pressure of 1 to 30 MPa, and a press time of 1 to 60 minutes. As the heat treatment conditions, for example, the heat treatment can be performed at 60 to 200 ° C. for 1 to 24 hours in an oven or the like.

As a method for producing the polymer composite piezoelectric body by the melting method, for example, a powdery or pellet-shaped resin composition (the above-mentioned polymer, composite filler, optionally a resin composition containing a dispersant and / or a leveling agent) can be used. Examples thereof include a method of melt kneading and hot pressing. The hot pressing conditions are not particularly limited, and the pressing temperature is preferably higher than the melting temperature or softening temperature of the polymer, and more preferably 20 ° C. or higher than the melting temperature or softening temperature. Further, the press pressure can be exemplified in the range of 1 to 30 MPa. In order to obtain a resin composition in which the composite filler is uniformly dispersed, it is basically preferable that the pressure is high, but it is appropriate depending on the fluidity and the desired physical properties (which direction the piezoelectric characteristics are emphasized, etc.). It is preferable to change and apply appropriate pressure. The press time is preferably performed within a range that does not impair the characteristics of the polymer composite piezoelectric body, and a range of 1 to 20 minutes can be exemplified. If the press time is 1 minute or more, the polymer and the composite filler can be sufficiently mixed, and if it is 20 minutes or less, the decrease in the molecular weight of the polymer can be suppressed and the physical properties of the polymer composite piezoelectric body are not impaired. ..

The resin composition thus molded can be further subjected to a polling treatment to form a polymer composite piezoelectric body. As a method of polling processing, corona polling or contact polling can be exemplified. Since corona polling can continuously process a roll-shaped polymer composite piezoelectric body, it can be preferably used for producing a large-area polymer composite piezoelectric body. For corona polling, for example, a molded resin composition is placed on a flat plate-shaped or roll-shaped electrode equipped with a heating means, and a high voltage is applied to a needle-shaped electrode about 1 to 50 mm away from the molded resin composition. Can be done at. The temperature of the heating means can be appropriately selected depending on the type and composition of the polymer and the composite filler constituting the polymer composite piezoelectric body, and can be exemplified in the range of 40 to 120 ° C. The applied voltage is not particularly limited as long as the resin composition can be polarized, and a range of 1 to 20 kV can be exemplified. The application time is not particularly limited, and a range of 10 to 600 seconds can be exemplified. The corona polling can be performed in a plurality of times, for example, 10 seconds can be performed 10 times. On the other hand, the contact polling can be preferably used when the resin composition is laminated or when it is patterned for producing a piezoelectric element or the like. The contact polling can be performed, for example, by sandwiching the upper and lower parts of the molded resin composition with a flat plate electrode and directly applying a voltage. The flat plate electrode may be heated, and the temperature thereof can be appropriately selected depending on the type and composition of the polymer and the composite filler, and the range of 40 to 120 ° C. can be exemplified. The applied electric field strength is not particularly limited as long as the resin composition can be polarized, and the range of 1 to 20 kV / mm can be exemplified. The application time is not particularly limited, and a range of 1 to 60 minutes can be exemplified.

<Piezoelectric element>
The piezoelectric element of the present invention includes a conductive layer on one side or both sides of the polymer composite piezoelectric body. The conductive layer is not particularly limited, and palladium, iron, aluminum, copper, nickel, platinum, gold, silver, chromium, molybdenum, indium tin oxide, PEDOT / PSS, carbon, conductive paste and the like can be used. Above all, it is preferable to use aluminum, copper, platinum, gold, silver, indium tin oxide, PEDOT / PSS, or a conductive paste. The thickness of the conductive layer is not particularly limited, but is preferably in the range of 0.1 to 20 μm. Further, the conductive layer can be provided with a portion that protrudes in a convex shape for pulling out the electrode. The method for forming such a conductive layer is not particularly limited, and a vapor deposition method such as vacuum deposition or sputtering, a spin coating method, a spray coating method, a roll coating method, a gravure coating method, a cast coating method, an inkjet method, etc. It can be performed by using a known method such as a screen printing method or a flexographic printing method.

The piezoelectric element of the present invention may be further provided with an insulating layer on the outside of the conductive layer for the purpose of protecting the polymer composite piezoelectric body and the conductive layer, and improving mechanical strength and handleability. The insulating layer is not particularly limited as long as it can impart insulating properties and mechanical properties, and is not particularly limited. Polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polymethyl methacrylate. , Polyethylene, elastomer, thermosetting resin, photocurable resin, or glass can be exemplified. Among them, the heat-resistant insulating layer such as polyethylene naphthalate having a heat shrinkage rate of less than 3.0% in the range of 150 to 200 ° C. is subjected to a heat pressing process for smoothing the surface of the polymer composite piezoelectric body. In addition, it can be preferably used because it can withstand a standing test and a drive test at a high temperature. The thickness of the insulating layer is not particularly limited, but is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less. When the thickness of the insulating layer is 100 μm or less, it is possible to efficiently convert mechanical energy and electrical energy.

The laminated structure of the piezoelectric element of the present invention is not particularly limited, but is a two-layer structure of a polymer composite piezoelectric / conductive layer, a three-layer structure of a conductive layer / a polymer composite piezoelectric / a conductive layer, and a first insulating layer. / First conductive layer / Polymer composite piezoelectric body / Second conductive layer / Five-layer structure of second insulating layer, first insulating layer / First conductive layer / First polymer composite piezoelectric body / The seven-layer structure of the second conductive layer / the second polymer composite piezoelectric body / the third conductive layer / the second insulating layer can be exemplified, and the number of layers and the material of the laminated structure can be appropriately changed according to the required characteristics. good. When the piezoelectric element includes a plurality of conductive layers, insulating layers, or polymer composite piezoelectric bodies, each layer may have the same component or different components. Further, the piezoelectric element may include a layer other than the polymer composite piezoelectric body, the conductive layer, and the insulating layer.

The method for manufacturing the piezoelectric element having such a laminated structure is not particularly limited, but it is preferable to use a screen printing method. The first method for manufacturing a piezoelectric element having a five-layer structure of a first insulating layer / a first conductive layer / a polymer composite piezoelectric layer / a second conductive layer / a second insulating layer using a screen printing method is as follows. A step of forming a first conductive layer by screen-printing a conductive paste on the insulating layer of the above, and screen-printing a liquid resin composition on the first electrode layer, and then applying a solvent. A step of forming a polymer composite piezoelectric body by drying and further performing a polling process, a step of forming a second conductive layer by screen printing a conductive paste on the polymer composite piezoelectric body, a second step. An example is a step of forming a second insulating layer by screen-printing a thermosetting resin on a conductive layer and then thermocuring the resin. As the screen material used in the screen printing method, stainless steel, nylon, polyester, etc. can be used, and the screen structure has a mesh number of 60 to 650, an aperture ratio of 30 to 70%, and an opening of 20 to 300 μm. It can be exemplified. The screen printing conditions are not particularly limited, and are squeegee pressing in the range of 0.01 to 0.5 MPa, squeegee angle in the range of 45 to 90 °, squeegee attack angle in the range of 30 to 90 °, and squeegee attack angle in the range of 60 to 90 °. Examples can be made of squeegee hardness in the range, squeegee speed in the range of 10 to 150 mm / s, and clearance in the range of 1.0 to 20 mm.

Hereinafter, the present invention will be described in more detail by way of examples, but the following examples are merely intended as illustrations. The scope of the present invention is not limited to this embodiment.
The measurement method or definition of the physical property values used in the examples is shown below.

<Average fiber diameter and aspect ratio of metal oxide fibers>
Using a scanning electron microscope (SU-8000) manufactured by Hitachi, Ltd., observe the obtained composite filler at a magnification of 5000 to 30,000, and use image analysis software to observe the fibers of 100 or more metal oxide fiber portions. The length and fiber diameter were measured, the average value of the fiber diameter was taken as the average fiber diameter, and the average value of (fiber length) / (fiber diameter) was taken as the aspect ratio.
<Average particle size and aspect ratio of piezoelectric ceramic particles>
Using a scanning electron microscope (SU-8000) manufactured by Hitachi, Ltd., observe the obtained composite filler at a magnification of 5000 to 30,000 times, and use image analysis software to observe the most of the piezoelectric ceramic particle parts at 100 or more locations. The major axis and the shortest diameter were measured, and the average value of (longest diameter + shortest diameter) / 2 was taken as the average particle diameter, and the average value of (longest diameter) / (shortest diameter) was taken as the aspect ratio.
<Piezoelectric constant d ₃₃ of polymer composite piezoelectric body>
Using a _d33 meter manufactured by Reed Techno, a polymer composite piezoelectric material was sandwiched between terminals with 1N, and the piezoelectric constant _d33 was measured under the conditions of preload force 1N and load force 4N. The average value of the d ₃₃ values of the nine points obtained by the measurement was taken as the d ₃₃ of the polymer composite piezoelectric body.
<Relative permittivity of polymer composite piezoelectric material>
Conductive surfaces are formed on both sides of the polymer composite piezoelectric material with a conductive paste (Dotite (D-362) manufactured by Fujikura Kasei Co., Ltd.), and an impedance analyzer (IM 3570) manufactured by Hioki Electric Co., Ltd. and a super-insulation meter. Using a shield box (SME-8350), the capacitance at a frequency of 1 kHz was measured and the relative permittivity was calculated.
<Voltage output constant g ₃₃ of polymer composite piezoelectric body>
The voltage output constant g ₃₃ of the polymer composite piezoelectric body was calculated from the piezoelectric constant d ₃₃ of the polymer composite piezoelectric body and the relative permittivity by the following relational expression. Here, the dielectric constant of the vacuum used was a value of 8.854 × ^10-12 C / Vm.
g ₃₃ = d ₃₃ ÷ (relative permittivity) ÷ (vacuum permittivity)

Hereinafter, a case where barium titanate fiber is used as the metal oxide fiber and barium titanate particles are used as the piezoelectric ceramic particles will be described, but the present invention is not limited thereto.

[Example 1]
<Preparation of spinning solution>
A uniform first solution was obtained by dissolving 7.89 parts by weight of barium carbonate in a mixed solvent of 30 parts by weight of acetic acid and 0.03 parts by weight of ion-exchanged water. Next, 1.8 parts by weight of polyvinylpyrrolidone and 11.25 parts by weight of titanium tetraisopropoxide were dissolved in 28.2 parts by weight of propylene glycol monomethyl ether, and then barium titanate particles (BT-UP2 manufactured by Nippon Chemical Industrial Co., Ltd.; An average particle diameter of 2 μm, see FIG. 4) 9.33 parts by weight was blended and subjected to ultrasonic treatment for 5 minutes to obtain a second solution in which barium titanate particles were dispersed. A spinning solution was prepared by mixing the second solution with the obtained first solution.

<Preparation of composite filler>
The spinning solution prepared by the above method is supplied to a nozzle having an inner diameter of 0.22 mm at 2.0 mL / hr by a syringe pump, a voltage of 25 kV is applied to the nozzle, and a composite filler precursor is applied to a grounded collector for 10 hours. Spinned. The distance between the nozzle and the collector was 15 cm, and the temperature of the spinning space was 25 ° C. The entire amount of the composite filler precursor obtained by the electrostatic spinning method is heated to 1150 ° C. in air at a heating rate of 10 ° C./min, held at a firing temperature of 1150 ° C. for 2 hours, and then cooled to room temperature. As a result, a composite filler aggregate was prepared. Further, the total amount of the obtained composite filler aggregate was placed on a screen mesh having an opening of 300 μm, filtered with a brush and pulverized to obtain 4.5 parts by weight of the composite filler. The average fiber diameter of the barium titanate fiber in the obtained composite filler is 0.3 μm and the aspect ratio is 5, the average particle size of the barium titanate particles is 2 μm and the aspect ratio is 1.1, and the barium titanate fiber. The molar ratio of barium titanate to barium titanate particles was 1: 1 and the barium titanate fibers and barium titanate particles were integrated. Scanning electron micrographs of the obtained composite filler are shown in FIGS. 1 and 2.

<Manufacturing of polymer composite piezoelectric body>
1.94 parts by weight of the composite filler prepared by the above method, 2.25 parts by weight of N, N-dimethylformamide, 0.25 part by weight of a copolymer of polyvinylidene fluoride and hexafluoropropylene (Kynar UltraFlex B manufactured by Arkema). , 0.02 part by weight of a polymer dispersant (PB821 manufactured by Ajinomoto Fine-Techno) was mixed to prepare a liquid resin composition. Then, using an applicator, the resin composition is cast on a glass substrate so that the thickness of the coating film is 600 μm, and heated on a hot plate at 90 ° C. to evaporate N, N-dimethylformamide. As a result, the resin composition was formed into a film. The film-like resin composition is peeled off from the glass substrate, hot-pressed under the conditions of a temperature of 200 ° C., a pressure of 10 MPa, and a time of 3 minutes, and then corona polling treatment is performed using a charging device (model number: KTN-15A) manufactured by Kasuga Electric Co., Ltd. By doing so, a polymer composite piezoelectric body was obtained. The corona polling treatment was carried out by applying a voltage of 6 kV for 100 seconds while heating the film-like resin composition to 60 ° C. The piezoelectric constant d ₃₃ of the obtained polymer composite piezoelectric body was 115.7 pC / N, the relative permittivity was 71, and the voltage output constant g ₃₃ was 184 mVm / N.

[Example 2]
A composite filler of 6.6 parts by weight was obtained in the same manner as in Example 1 except that the blending amount of the barium titanate particles was 18.66 parts by weight. The average fiber diameter of the barium titanate fiber in the obtained composite filler is 0.3 μm and the aspect ratio is 5, the average particle size of the barium titanate particles is 2 μm and the aspect ratio is 1.1, and the barium titanate fiber. The molar ratio of barium titanate to barium titanate particles was 1: 2, and the barium titanate fibers and barium titanate particles were integrated.
Next, using this composite filler, a polymer composite piezoelectric body was produced in the same manner as in Example 1. The piezoelectric constant d ₃₃ of the obtained polymer composite piezoelectric body was 116.3 pC / N, the relative permittivity was 27, and the voltage output constant g ₃₃ was 486 mVm / N.

[Comparative Example 1]
2.3 parts by weight of barium titanate fiber was obtained in the same manner as in Example 1 except that the barium titanate particles were not blended. The average fiber diameter of the barium titanate fiber was 0.3 μm, the aspect ratio was 5, and there were no piezoelectric ceramic particles. A scanning electron micrograph of the obtained barium titanate fiber is shown in FIG.
Next, 1.94 parts by weight of barium titanate fiber, 2.25 parts by weight of N, N-dimethylformamide, 0.25 part by weight of a copolymer of polyvinylidene fluoride and hexafluoropropylene (Kynar UltraFlex B manufactured by Arkema), A liquid resin composition was prepared by mixing with 0.02 part by weight of a polymer dispersant (PB821 manufactured by Ajinomoto Fine-Techno). Using this liquid resin composition, a polymer composite piezoelectric body was produced in the same manner as in Example 1. The piezoelectric constant d ₃₃ of the obtained polymer composite piezoelectric body is 105.7 pC / N, the relative permittivity is 67, the voltage output constant g ₃₃ is 178 mVm / N, the voltage output constant is slightly low, and the voltage output constant is slightly low. The yield of barium titanate fiber obtained by spinning for 10 hours was as low as 2.3 parts by weight.

[Example 3]
Similar to Comparative Example 1, barium titanate fibers having an average fiber diameter of 0.3 μm and an aspect ratio of 5 were produced. Next, 0.97 parts by weight of barium titanate fiber and 0.97 parts by weight of barium titanate particles (BT-UP2 manufactured by Nippon Chemical Industrial Co., Ltd .; average particle diameter 2 μm, see FIG. 4) were mixed to obtain a composite filler. rice field. The average fiber diameter of the barium titanate fiber in the obtained composite filler is 0.3 μm and the aspect ratio is 5, the average particle size of the barium titanate particles is 2 μm and the aspect ratio is 1.1, and the barium titanate fiber. The molar ratio of barium titanate to barium titanate particles was 1: 1 and the barium titanate fibers and barium titanate particles were not integrated.
Next, using this composite filler, a polymer composite piezoelectric body was produced in the same manner as in Example 1. The piezoelectric constant d ₃₃ of the obtained polymer composite piezoelectric body was 78.8 pC / N, the relative permittivity was 48, and the voltage output constant g ₃₃ was 185 mVm / N.

[Example 4]
Similar to Comparative Example 1, barium titanate fibers having an average fiber diameter of 0.3 μm and an aspect ratio of 5 were produced. Next, 0.65 parts by weight of barium titanate fiber and 1.29 parts by weight of barium titanate particles (BT-UP2 manufactured by Nippon Chemical Industrial Co., Ltd .; average particle diameter 2 μm, see FIG. 4) were mixed to obtain a composite filler. rice field. The average fiber diameter of the barium titanate fiber in the obtained composite filler is 0.3 μm and the aspect ratio is 5, the average particle size of the barium titanate particles is 2 μm and the aspect ratio is 1.1, and the barium titanate fiber. The molar ratio of barium titanate to barium titanate particles was 1: 2, and the barium titanate fibers and barium titanate particles were not integrated.
Next, using this composite filler, a polymer composite piezoelectric body was produced in the same manner as in Example 1. The piezoelectric constant d ₃₃ of the obtained polymer composite piezoelectric body was 60.1 pC / N, the relative permittivity was 28, and the voltage output constant g ₃₃ was 242 mVm / N.

[Comparative Example 2]
Barium titanate particles (BT-UP2 manufactured by Nippon Chemical Industrial Co., Ltd .; average particle diameter 2 μm, see FIG. 4) were prepared as fillers for the polymer composite piezoelectric body. The average particle size of the barium titanate particles was 2 μm, the aspect ratio was 1.1, and no metal oxide fibers were present.
Next, 1.94 parts by weight of barium titanate particles, 2.25 parts by weight of N, N-dimethylformamide, 0.25 parts by weight of a copolymer of polyvinylidene fluoride and hexafluoropropylene (Kynar UltraFlex B manufactured by Arkema), A liquid resin composition was prepared by mixing with 0.02 part by weight of a polymer dispersant (PB821 manufactured by Ajinomoto Fine-Techno). Using this liquid resin composition, a polymer composite piezoelectric body was produced in the same manner as in Example 1. The piezoelectric constant d ₃₃ of the obtained polymer composite piezoelectric body is 41.0 pC / N, the relative permittivity is 92, the voltage output constant g ₃₃ is 50 mVm / N, and the voltage output constant and the piezoelectric constant are both. It was low.

The voltage output constants of the polymer composite piezoelectric bodies using the composite fillers of Examples 1 to 4 were 180 mVm / N or more, which were high. In particular, the piezoelectric constants of the polymer composite piezoelectric materials of Examples 1 and 2 using the composite filler in which the metal oxide fibers and the piezoelectric ceramic particles are integrated are 100 pC / N or more, which are high. rice field. Further, as compared with Comparative Example 1, the composite fillers of Examples 1 and 2 had a higher yield per unit time. From the above, by using a composite filler containing a metal oxide fiber having a specific shape and piezoelectric ceramics, a polymer composite piezoelectric material having a high voltage output constant, or a polymer having a high piezoelectric constant and a high voltage output constant. The result was that a composite piezoelectric material was obtained. Further, the composite filler of the present invention has a high yield per unit time, and it has become possible to manufacture a filler for a polymer composite piezoelectric body having a high piezoelectric constant and a high voltage output constant at low cost.

By using the composite filler of the present invention as a filler for a polymer composite piezoelectric body, it is possible to provide a polymer composite piezoelectric body having a high voltage output constant or a high voltage output constant and a high voltage output constant at low cost. Therefore, it can be suitably used as an electroacoustic conversion device such as a speaker or a buzzer, an actuator, a display, a tactile device, a sensor, a power generation device, or the like.

1 A state in which the surface of the metal oxide fiber and the surface of the piezoelectric ceramic particles are fused 2 A state in which a part of the piezoelectric ceramic particles is partially embedded in the metal oxide fiber.

Claims (12)

A composite containing metal oxide fibers having an average fiber diameter of 0.1 to 10 μm and an aspect ratio of 2 or more and piezoelectric ceramic particles having an average particle diameter of 0.01 to 200 μm and an aspect ratio of less than 2. Filler. The composite filler according to claim 1, wherein the metal oxide fiber and the piezoelectric ceramic particles are integrated. The composite filler according to claim 1 or 2, wherein the composition of the metal oxide fiber is mainly composed of a titanium acid metal salt, and the composition of the piezoelectric ceramic particles is mainly composed of a titanium acid metal salt or a niobic acid alkali metal salt. .. The composite filler according to any one of claims 1 to 3, wherein the molar ratio of the metal oxide fiber to the piezoelectric ceramic particles is in the range of 1: 0.1 to 1:10. A resin composition containing the composite filler according to any one of claims 1 to 4 and a polymer. The resin composition according to claim 5, wherein the ratio of the composite filler to the total amount of the composite filler and the polymer is 10 to 90% by volume. The resin composition according to claim 5 or 6, further comprising 0.1 to 10% by weight of a dispersant and / or 0.1 to 10% by weight of a leveling agent with respect to the composite filler. The resin composition according to any one of claims 5 to 7, further comprising a solvent. The resin composition according to any one of claims 5 to 8, which is used for producing a polymer composite piezoelectric body. A polymer composite piezoelectric body comprising the resin composition according to any one of claims 5 to 7. A piezoelectric element provided with a conductive layer on one side or both sides of the polymer composite piezoelectric material according to claim 10. A step of preparing a spinning solution containing a metal salt and piezoelectric ceramic particles having an average particle diameter of 0.01 to 200 μm and an aspect ratio of less than 2, and electrostatically spinning the spinning solution to prepare a composite filler precursor. A method for producing a composite filler, which comprises a step of firing the composite filler precursor to produce a composite filler aggregate, and a step of crushing the composite filler aggregate.

Images