WO2015167013A1 - Sound wave and shock detection element - Google Patents

Sound wave and shock detection element Download PDF

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Publication number
WO2015167013A1
WO2015167013A1 PCT/JP2015/063093 JP2015063093W WO2015167013A1 WO 2015167013 A1 WO2015167013 A1 WO 2015167013A1 JP 2015063093 W JP2015063093 W JP 2015063093W WO 2015167013 A1 WO2015167013 A1 WO 2015167013A1
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WO
WIPO (PCT)
Prior art keywords
sound wave
external force
detection element
impact detection
resin body
Prior art date
Application number
PCT/JP2015/063093
Other languages
French (fr)
Japanese (ja)
Inventor
米田　哲也
幸 山中
学 本居
佳郎 田實
Original Assignee
日本バルカー工業株式会社
学校法人関西大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本バルカー工業株式会社, 学校法人関西大学 filed Critical 日本バルカー工業株式会社
Priority to JP2016516424A priority Critical patent/JPWO2015167013A1/en
Publication of WO2015167013A1 publication Critical patent/WO2015167013A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G7/00—Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture
    • H01G7/02—Electrets, i.e. having a permanently-polarised dielectric
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/02—Microphones
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions

Definitions

  • the present invention relates to a sound wave / impact detection element.
  • the impact detection sensor can be used to detect the activation of airbags in automobiles, monitor precision devices such as hard disks, test when developing protective materials, sensors for measuring the number of vehicles and vehicle classification, and hitting sensors for game equipment and sports equipment. Can be used.
  • Patent Document 1 discloses a damper material, an ultrasonic transmission / reception element that is a polymer piezoelectric element, a composite piezoelectric element, or a coated ceramic piezoelectric element fixed to the front surface thereof, and further on the front surface thereof.
  • An ultrasonic probe constituted by a coated wear-resistant film is disclosed.
  • the present invention has been made in view of such problems, and an object of the present invention is to provide a sound wave / impact detection element excellent in sound wave / impact detection ability and durability.
  • the configuration of the present invention is as follows.
  • a sound wave / impact detection element having a porous resin body made of a resin having no dipole due to a molecule and a crystal structure, and an external force absorbing sheet.
  • the sound wave / impact detection element of the present invention is an element for detecting sound waves and / or shocks, and includes a porous resin body made of a resin having no dipole due to a molecule and a crystal structure, and an external force absorbing sheet. For this reason, the sound wave / impact detection element of the present invention is excellent in sound wave / impact detection ability and durability.
  • the sound wave / impact detection element of the present invention can be used for various inspections such as inspection of structural defects, diagnosis of human or animal diseases, determination of whether or not an impact of an object has exceeded an allowable level, a sounding instrument or a detector.
  • It can be used in the field, and can be suitably used for applications where it is desired to detect sound waves and impacts in an environment where the temperature is higher than room temperature or in an environment where a high pressure is applied (eg, an environment where the pressure is 1 MPa or more). It should also be used suitably for air bag activation judgment of automobiles, monitoring of precision equipment such as hard disks, testing during the development of protective materials, sensors for measuring the number of vehicles and vehicle classification, impact sensors for game equipment and sports equipment, etc. Can do.
  • the sound wave / impact detection element of the present invention is not particularly limited in its structure as long as it has the porous resin body and the external force absorbing sheet, but the external force absorbing sheet is laminated on the porous resin body.
  • a laminate in which an external force absorbing sheet is laminated on a porous resin body is preferable.
  • a laminate in which an external force absorbing sheet is laminated on the sheet-like porous resin body a laminate in which an external force absorbing sheet is laminated on at least one surface of a piezoelectric element including the sheet-like porous resin body. If it is, it will not be restrict
  • a sound wave / impact detecting element including a porous resin body that retains a high piezoelectric rate is obtained. From the viewpoint of ease of manufacturing, cost, etc., the front and back surfaces of the piezoelectric element including a sheet-like porous resin body are provided. A laminate in which an external force absorbing sheet is laminated is preferable. From the viewpoint of obtaining a sound wave / impact detection element including a porous resin body that retains a higher piezoelectric rate, the laminate includes a sheet-like porous resin body. A laminate in which an external force absorbing sheet is laminated on the entire surface of the piezoelectric element is preferable.
  • the sound wave / impact detection element of the present invention there may be a conventionally known layer or the like other than the porous resin body and the external force absorbing sheet.
  • the laminate includes the porous resin body and the external force absorbing member.
  • Conventionally used for sound wave detection elements and impact detection elements between the sheet and the side of the porous resin body that is opposite to the side that contacts the external force absorption sheet, and that that is opposite to the side of the external force absorption sheet that contacts the porous resin body
  • known layers such as an electrode layer, a surface smoothing layer, a protective layer, an insulating layer, and an adhesive layer may be present.
  • the external force absorbing sheet also serves to prevent the electric charge held in the porous resin body from being electrically connected to the external environment and attenuated. Obtainable.
  • the thickness of the laminate may be appropriately adjusted according to the application to be used and is not particularly limited, but is, for example, 50 ⁇ m to 50 mm, and preferably 100 ⁇ m to 10 mm.
  • a porous resin body made of a resin having no dipole due to the molecule and crystal structure is used as a piezoelectric material, and converts sound waves / impact into electric power by converting the sound wave / impact into electric power. It plays the role of detecting impact.
  • the porous resin body has high charge responsiveness to minute external force, high sound wave / impact detection ability, and can retain electric charge even in a high temperature environment. It is possible to obtain a sound wave / impact detecting element that is excellent in resistance, large in flexibility, excellent in impact resistance and heat resistance, and lightweight. Furthermore, since the porous resin body can be easily formed into an arbitrary shape such as a thin film or a large area, a sound wave / impact detection element having an arbitrary shape can be manufactured according to a desired application. .
  • the porous resin body is preferably a structure made of a resin capable of holding electric charge, and more preferably a structure made of a resin having heat resistance.
  • the resin having no dipole due to the molecule and crystal structure is not particularly limited as long as the molecule and crystal structure are not polar resins, but polyolefin resin (polyethylene, polypropylene, ethylene propylene resin, etc.), polyester resin Non-fluorinated resins such as resins (polyethylene terephthalate, etc.), polyurethane resins, polystyrene resins, silicone resins, etc., and polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA), tetrafluoro Examples thereof include fluorine resins such as ethylene-hexafluoropropylene copolymer (FEP).
  • FEP ethylene-hexafluoropropylene copolymer
  • a resin that has a high continuous usable temperature and does not have a glass transition point in the operating temperature range of the sound wave / impact detection element is preferable.
  • the continuous useable temperature can be measured by a continuous use temperature test described in UL746B (UL standard), preferably 50 ° C or higher, more preferably 100 ° C or higher, and further preferably 200 ° C or higher. .
  • the resin having these characteristics for example, polyolefin resin and fluorine resin are preferable, fluorine resin is more preferable, and PTFE is particularly preferable.
  • the porous resin body may contain a conventionally known additive in addition to the resin as long as the effects of the present invention are not impaired.
  • a conventionally known additive in addition to the resin as long as the effects of the present invention are not impaired.
  • matrix resin and charge-induced hollow particles particles in which a conductive substance is attached to at least a part of the surface of the hollow particles
  • the structure containing these may be sufficient.
  • the porous resin body has a porosity calculated by the following formula of preferably 60% or more, more preferably 80 to 99%.
  • a porous resin body having a porosity in the above range is preferable because of its high charge retention amount.
  • Porosity (true resin density ⁇ apparent density) ⁇ 100 / true resin density
  • apparent density a value calculated using the weight of the porous resin body and the apparent volume is used.
  • the shape of the porous resin body may be appropriately selected according to the application to be used, but is preferably a sheet from the viewpoint of ease of production, sound wave / impact detection properties, and the like.
  • the thickness is not particularly limited, but is, for example, 10 ⁇ m to 1 mm, and preferably 50 ⁇ m to 500 ⁇ m.
  • the porous resin body can be obtained by various conventionally known methods. For example, a method of forming pores using the phase change of the solution containing the resin (phase separation method), a method of mixing and dispersing additives for pore formation in the resin and removing them after molding (extraction) Method), molding the resin, and then chemically cutting the bond of a part of the molded body, or conversely performing a binding reaction (chemical treatment method), stretching the resin, A method of forming micropores in the microfibril structure part, a method of mixing and dispersing additives and forming pores during stretching (stretching method), and a method of forming pores by irradiating neutron beams, lasers, etc.
  • phase separation method phase separation method
  • a method of mixing and dispersing additives for pore formation in the resin and removing them after molding (extraction) Method molding the resin, and then chemically cutting the bond of a part of the molded body, or conversely performing a binding reaction (chemical treatment method), stretching the resin
  • Irradiation etching method a method of forming a porous body by fusing resin fine pieces by heating or the like (fusion method), a method of forming pores using a foaming agent (foaming method), Method to form pores by combining (composite method), dry spinning, wet spinning, dry Wherein spinning, melt spinning, to form a fiber (fiber) from the resin by electrospinning like, a method of forming a woven or nonwoven fabric using the fiber and the like.
  • the porous resin body is preferably a structure including a nonwoven fabric or a woven fabric formed from fibers made of resin from the viewpoint of durability and long-term deformation performance can be maintained.
  • the structure may include the non-woven fabric or woven fabric, or may be a structure made of only the non-woven fabric or woven fabric, or a laminate in which a conventionally known layer is laminated on the surface of the non-woven fabric or woven fabric. Also good.
  • the average fiber diameter of the fiber is preferably 0.05 to 50 ⁇ m, more preferably 0.1 to 20 ⁇ m, and further preferably 0.5 ⁇ m to 5 ⁇ m.
  • a porous resin body containing fibers having an average fiber diameter in the above range can form a sufficient space for holding electric charges by increasing the fiber surface area, and even if it is made into a thin film, the fiber distribution uniformity is increased. It is preferable in that it can be used.
  • the average fiber diameter can be adjusted by appropriately selecting the conditions for forming the fiber.For example, when the fiber is formed by electrospinning, the humidity is reduced during electrospinning, and the nozzle diameter is adjusted. There is a tendency that the average fiber diameter of the obtained fiber can be reduced by decreasing the voltage, increasing the applied voltage, or increasing the voltage density.
  • the average fiber diameter was determined by observing the fiber (group) to be measured with a scanning electron microscope (SEM) (magnification: 10000 times), and randomly selecting 20 fibers from the obtained SEM image. The fiber diameter (major diameter) of each fiber is measured, and is an average value calculated based on the measurement result.
  • SEM scanning electron microscope
  • the fiber diameter variation coefficient of the fiber calculated by the following formula is preferably 0.7 or less, more preferably 0.01 to 0.5.
  • the fiber diameter variation coefficient is within the above range, the fiber has a uniform fiber diameter, and the nonwoven fabric obtained using the fiber has a higher porosity. Since it is obtained, it is preferable.
  • Fiber diameter variation coefficient standard deviation / average fiber diameter (“standard deviation” is the standard deviation of the fiber diameters of the 20 fibers)
  • the fiber length of the fiber is preferably 0.1 to 1000 mm, more preferably 0.5 to 100 mm, and still more preferably 1 to 50 mm.
  • the method for forming the fiber is not particularly limited, but the fiber obtained by the electrospinning method has a small fiber diameter, and the nonwoven fabric obtained by using the fiber has a high hollow ratio and a high specific surface area. From the viewpoint of obtaining a porous resin body having piezoelectric characteristics, the electrospinning method is preferable.
  • a porous resin body can be produced by accumulating the obtained fibers into a nonwoven fabric or weaving them into a woven fabric and molding them.
  • Electrospinning method When forming a fiber made of a resin using the electrospinning method, for example, a spinning solution containing the resin and, if necessary, a solvent is used.
  • the ratio of the resin contained in the spinning solution is, for example, 5 to 100% by weight, preferably 5 to 80% by weight, and more preferably 10 to 70% by weight.
  • the solvent is not particularly limited as long as it can dissolve or disperse the resin.
  • water dimethylacetamide, dimethylformamide, tetrahydrofuran, methylpyrrolidone, xylene, acetone, chloroform, ethylbenzene, cyclohexane, benzene, sulfolane.
  • solvents may be used alone or in combination of two or more.
  • the solvent is contained in the spinning solution in an amount of, for example, 0 to 90% by weight, preferably 10 to 90% by weight, more preferably 25 to 80% by weight.
  • the spinning solution may further contain additives such as a surfactant, a dispersant, a charge adjusting agent, a functional particle, an adhesive, a viscosity adjusting agent, and a fiber forming agent in addition to the resin and the solvent.
  • additives such as a surfactant, a dispersant, a charge adjusting agent, a functional particle, an adhesive, a viscosity adjusting agent, and a fiber forming agent in addition to the resin and the solvent.
  • the fiber forming agent is preferably a polymer having high solubility in a solvent, such as polyethylene oxide, polyethylene glycol, dextran, alginic acid, chitosan, starch, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, Examples thereof include cellulose and polyvinyl alcohol.
  • a solvent such as polyethylene oxide, polyethylene glycol, dextran, alginic acid, chitosan, starch, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, Examples thereof include cellulose and polyvinyl alcohol.
  • the amount of the fiber-forming agent used is, for example, 0.1 to 15% by weight, preferably 1 to 10% by weight in the spinning solution, although it depends on the viscosity of the solvent and the solubility of the resin in the solvent. .
  • the spinning solution can be produced by mixing the resin and, if necessary, a solvent and an additive by a conventionally known method.
  • spinning solution examples include the following spinning solution (1).
  • Spinning liquid (1) 30 to 70% by weight, preferably 35 to 60% by weight of PTFE, 0.1 to 10% by weight, preferably 1 to 7% by weight, and a total of 100% by weight Spinning solution containing solvent
  • the applied voltage at the time of electrospinning is preferably 1 to 100 kV, more preferably 5 to 50 kV, and still more preferably 10 to 40 kV.
  • the tip diameter (outer diameter) of the spinning nozzle used for electrospinning is preferably 0.1 to 2.0 mm, more preferably 0.2 to 1.6 mm.
  • the applied voltage is preferably 10 to 50 kV, more preferably 10 to 40 kV, and the tip diameter (outer diameter) of the spinning nozzle is used. ) Is preferably 0.3 to 1.6 mm.
  • a method for producing the fiber a method for producing a fiber made of PTFE by an electrospinning method will be specifically described.
  • a method for producing the PTFE fiber a conventionally known production method can be employed, and examples thereof include the following methods described in JP-T-2012-515850.
  • Providing a spinning solution comprising PTFE, a fiber forming agent and a solvent and having a viscosity of at least 50,000 cP Spinning the spinning solution from a nozzle and forming a fiber by electrostatic traction; Collecting the fibers on a collector (eg, a take-up spool) to form a precursor; Calcining the precursor to remove the solvent and the fiber former to form PTFE fibers.
  • the step of forming the fiber and the step of collecting the obtained fibers into a sheet to form the nonwoven fabric may be performed separately or simultaneously.
  • a nonwoven fabric may be formed by collecting fibers while collecting fibers).
  • a step of forming a fiber by using an electrospinning method and a step of collecting the obtained fibers into a sheet to form a nonwoven fabric may be simultaneously performed, or a step of forming a fiber. After performing, you may perform the process of accumulating the fiber obtained by the wet method in a sheet form, and forming a nonwoven fabric.
  • Examples of a method for forming a nonwoven fabric by the wet method include a method of forming (paper making) a sheet by depositing (accumulating) the fibers on a mesh using an aqueous dispersion containing the fibers. .
  • the amount of fiber used in this wet method is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total amount of the aqueous dispersion. If the fiber is used within this range, water can be efficiently used in the process of depositing the fiber, and the dispersion state of the fiber is improved, so that a uniform wet nonwoven fabric can be obtained.
  • the aqueous dispersion is added with a dispersant or an oil agent composed of a cationic, anionic, or nonionic surfactant, or an antifoaming agent that suppresses the generation of bubbles. May be.
  • the woven fabric formed from the fiber can be manufactured by a method including a step of forming a fiber and a step of weaving the obtained fiber into a sheet to form a woven fabric.
  • a method of weaving the fiber into a sheet a conventionally known weaving method can be used, and methods such as a water jet room, an air jet room, and a rapier room can be used.
  • the basis weight of the nonwoven fabric and the woven fabric is preferably 100 g / m 2 or less, more preferably 0.1 to 50 g / m 2 , and still more preferably 0.1 to 20 g / m 2 .
  • the thickness of the nonwoven fabric and woven fabric is usually 10 ⁇ m to 1 mm, preferably 50 ⁇ m to 500 ⁇ m.
  • the basis weight and thickness tend to increase by increasing the spinning time or increasing the number of spinning nozzles.
  • the non-woven fabric and woven fabric are obtained by accumulating or weaving the fibers in a sheet shape.
  • Such non-woven fabric and woven fabric are composed of a single layer, or composed of two or more layers having different materials and fiber diameters. Any of these may be used.
  • the porous resin body is preferably subjected to polarization treatment.
  • polarization treatment a conventionally known method can be used, and is not particularly limited, and examples thereof include voltage application processing such as DC voltage application processing and AC voltage application processing, and corona discharge processing.
  • the corona discharge treatment can be performed using a commercially available device composed of a high voltage power source and electrodes.
  • the discharge conditions may be appropriately selected according to the porous resin body to be used.
  • the voltage of the high-voltage power source is -0.1 to -100 kV, more preferably -1 to -20 kV, and the current is 0.1. 1 to 100 mA, more preferably 1 to 80 mA, the distance between the electrodes is 0.1 to 100 cm, more preferably 1 to 10 cm, and the applied voltage is 0.01 to 10.0 MV / m, more preferably 0.5 to 2.
  • a condition of 0 MV / m is mentioned.
  • the polarization treatment may be performed on a porous resin body alone, but as a sound wave / impact detection element of the present invention, a laminate of a porous resin body and an external force absorbing sheet or the above-described conventionally known layer is used.
  • a polarization treatment after forming the stacked body, for example, after stacking an insulating layer.
  • the layer laminated on the porous resin body serves to prevent the electric charge held in the porous resin body from being attenuated by being electrically connected to the external environment.
  • an impact detection element can be obtained, and a new interface that can hold electric charge between the porous resin body and the layer laminated on the porous resin body tends to be formed. This is because it is considered that the piezoelectricity of the porous resin body in the sound wave / impact detection element is improved.
  • the external force absorbing sheet (also referred to as “stress absorbing sheet”) absorbs the external force applied to the porous resin body, and the porous resin body is completely compressed by the external force (the porosity becomes 0%). Any sheet that can prevent this is not particularly limited.
  • the external force means a force applied to the element from the outside of the sound wave / impact detection element of the present invention, such as pressure or impact.
  • the external force absorption rate of the external force absorbing sheet is preferably 50% or more, more preferably 80 to 100%. Since the sound absorption rate is within the above range, it is possible to prevent the porous resin body from being completely compressed by the external force (the porosity becomes 0%). In addition, a sensing element having excellent durability can be obtained.
  • the detection element of the present invention is a sound wave detection element.
  • the detecting element of the present invention is an element that detects the presence of an impact (external force) that cannot be absorbed by the external force absorbing sheet, and the external force absorbing sheet It is an element which detects the sound wave which permeate
  • the external force absorption rate is the impact (X: voltage value) when an external force absorbing sheet is not used when a load cell is used and an iron ball having a height of 500 mm to 30 g above the load cell is freely dropped.
  • X voltage value
  • Y voltage value
  • the sound transmittance of the external force absorbing sheet is preferably 20% or more, and more preferably 50% or more.
  • the sound wave transmittance can be measured according to JIS A 1405-1.
  • the loss elastic modulus of the external force absorbing sheet is not particularly limited, but is preferably 1 ⁇ 10 3 to 1 ⁇ 10 7 Pa, more preferably 1 ⁇ 10 4 to 1 ⁇ 10 6 Pa.
  • a highly sensitive sound wave / impact detection element can be obtained.
  • the loss elastic modulus can be measured based on JIS K 7244.
  • the volume resistivity of the external force absorbing sheet is 1 ⁇ 10 13 ⁇ ⁇ cm or more, preferably 1 ⁇ 10 14 ⁇ ⁇ cm or more. If it exists in this range, it is preferable at the point of the long-term charge retention improvement of a porous resin body.
  • the volume resistivity is measured based on the double ring electrode method using an external force absorbing sheet to be measured.
  • the thickness of the external force absorbing sheet is not particularly limited, and is preferably such that the external force absorption rate, the sound wave transmittance, and the loss elastic modulus are within the above ranges, preferably 0.05 to 10 mm, and more preferably. Is 0.1 to 5 mm.
  • the external force absorbing sheet is not particularly limited, and is preferably a sheet made of a material having an external force absorption rate, a sound wave transmittance, and a loss elastic modulus within the above ranges, and has excellent adhesion to the porous resin body.
  • a sheet made of an organic polymer is preferable, and a sheet made of a heat resistant organic polymer is more preferable from the viewpoint of obtaining a sound wave / impact detecting element excellent in heat resistance.
  • the external force absorption sheet is preferably a porous sheet or a gel sheet.
  • thermosetting polymer examples include polyimide, epoxy resin, thermosetting rubber (eg, vinylidene fluoride rubber, silicone rubber), polyurethane, phenolic resin, imide resin (eg, polyimide, polyamideimide, bismaleimide), silicone Examples thereof include resins.
  • Thermoplastic polymers include acrylic resin, methacrylic resin, polypropylene, polyamide, vinyl chloride resin, silicone resin, fluororesin (eg PTFE, PCTFE, ETFE, PVdF, PFA, FEP), nylon, polystyrene, high density polyethylene, Examples thereof include low density polyethylene, polyphenylene sulfide, polyethylene oxide, polysulfone, and vinylidene chloride. From the viewpoint of external force absorption characteristics, it is preferable to use a material having a high elastic modulus as the organic polymer, for example, it is preferable to use a thermosetting rubber.
  • the external force absorbing sheet can be formed by a conventionally known method.
  • Examples of such a method include a method of forming a sheet by applying and drying a polymer liquid containing an organic polymer and a solvent on at least one surface of the porous resin body, and a porous resin body on the polymer liquid.
  • seat by immersing and drying is mentioned.
  • the sound wave / impact detection element of the present invention may be manufactured by forming an external force absorbing sheet in advance by a conventionally known method and laminating the sheet on a porous resin body by a conventionally known method.
  • Example 1 A sheet-like nonwoven fabric (thickness 0.06 mm, empty) formed from PTFE fiber, which is a porous resin body, by accumulating PTFE fibers in a sheet form by the electrospinning method described in JP-T-2012-515850. A porosity of 95%, an average fiber diameter of 900 nm) was obtained, and a PFA sheet (thickness: 0.025 mm, manufactured by Daikin Industries, Ltd., NEOFLON PFA) as an insulating layer was layered on the upper and lower surfaces of the nonwoven fabric, and 300 ° C. for 60 minutes. A laminated sheet having an insulating layer formed on the front and back surfaces of the porous resin body was produced by thermocompression bonding.
  • Example 2 A sound wave / impact detection element was produced in the same manner as in Example 1 except that a gel-like sheet (manufactured by Taika Co., Ltd., Alpha Gel) was used as the external force absorbing sheet instead of the porous PTFE sheet.
  • a gel-like sheet manufactured by Taika Co., Ltd., Alpha Gel
  • a voltage was generated, and the generated voltage was detected. That is, the impact could be detected by the produced sound wave / impact detector.
  • Example 1 A device was produced in the same manner as in Example 1 except that the external force absorbing sheet was not provided. When a 100 g iron ball was dropped from 50 cm above the element in a state where a static pressure of 100 MPa was applied to the upper surface of the manufactured element, no voltage could be detected. That is, the manufactured element could not detect the impact.

Abstract

　Provided is a sound wave and shock detection element having: a porous resin body made from a resin free from dipoles which are caused by molecular and crystalline structures; and an external force-absorbing sheet.

Description

音波・衝撃検知素子Sound wave / impact detector
　本発明は、音波・衝撃検知素子に関する。 The present invention relates to a sound wave / impact detection element.
　音波、特に超音波検知センサーは、非破壊および無害でその内部等を調べることが可能なことから、構造物の欠陥の検査、人や動物の疾患の診断、測深機または探知機などの様々な分野に応用されている。
　また、衝撃検知センサーは、自動車等のエアバッグ起動判断やハードディスクなど精密機器の監視、防護用素材の開発時の試験、車両数及び車両分類計測用センサー、ゲーム機器やスポーツ機器用打撃センサーなどに活用することができる。 Since sound waves, especially ultrasonic sensors, can be examined non-destructively and harmlessly, etc., they can be used for various inspections such as inspection of structural defects, diagnosis of human and animal diseases, sounding instruments and detectors. Applied to the field.
In addition, the impact detection sensor can be used to detect the activation of airbags in automobiles, monitor precision devices such as hard disks, test when developing protective materials, sensors for measuring the number of vehicles and vehicle classification, and hitting sensors for game equipment and sports equipment. Can be used.
　音波を検知する素子として、例えば、特許文献１には、ダンパー材と、その前面に固着された、ポリマー圧電素子、コンポジット圧電素子または被覆セラミックス圧電素子である超音波送受信素子と、さらにその前面に被覆された耐摩耗性膜とによって構成されている超音波プローブが開示されている。 As an element for detecting sound waves, for example, Patent Document 1 discloses a damper material, an ultrasonic transmission / reception element that is a polymer piezoelectric element, a composite piezoelectric element, or a coated ceramic piezoelectric element fixed to the front surface thereof, and further on the front surface thereof. An ultrasonic probe constituted by a coated wear-resistant film is disclosed.
特開２００２－３６５２７０号公報JP 2002-365270 A
　しかしながら、音波や衝撃を検知する従来の検知素子には、長期特性維持など耐久性の観点で課題があり、さらなる改良の余地があった。
　本発明は、このような問題に鑑みてなされたものであり、音波・衝撃検知能および耐久性に優れる音波・衝撃検知素子を提供することを目的とする。 However, conventional sensing elements that detect sound waves and impacts have problems in terms of durability, such as maintaining long-term characteristics, and there is room for further improvement.
The present invention has been made in view of such problems, and an object of the present invention is to provide a sound wave / impact detection element excellent in sound wave / impact detection ability and durability.
　このような状況のもと、本発明者らは、前記課題を解決すべく鋭意検討した結果、分子および結晶構造に起因する双極子を持たない樹脂からなる多孔質樹脂体と外力吸収シートとを有する音波・衝撃検知素子によれば、前記の目的を達成できることを見出し、本発明を完成するに至った。
　本発明の構成は以下の通りである。 Under such circumstances, the present inventors have intensively studied to solve the above problems, and as a result, have obtained a porous resin body made of a resin having no dipole due to the molecule and crystal structure, and an external force absorbing sheet. According to the sound wave / impact detection element possessed, it has been found that the above object can be achieved, and the present invention has been completed.
The configuration of the present invention is as follows.
　［１］　分子および結晶構造に起因する双極子をもたない樹脂からなる多孔質樹脂体と、外力吸収シートとを有する音波・衝撃検知素子。 [1] A sound wave / impact detection element having a porous resin body made of a resin having no dipole due to a molecule and a crystal structure, and an external force absorbing sheet.
　［２］　前記多孔質樹脂体の空孔率が６０％以上である、［１］に記載の音波・衝撃検知素子。 [2] The sound wave / impact detection element according to [1], wherein the porosity of the porous resin body is 60% or more.
　［３］　前記樹脂がポリテトラフルオロエチレンである、［１］または［２］に記載の音波・衝撃検知素子。 [3] The sound wave / impact detection element according to [1] or [2], wherein the resin is polytetrafluoroethylene.
　［４］　前記多孔質樹脂体が、樹脂からなるファイバーから形成された不織布または織布を含む、［１］～［３］のいずれかに記載の音波・衝撃検知素子。
　［５］　前記ファイバーの平均繊維径が０．０５～５０μｍである、［４］に記載の音波・衝撃検知素子。 [4] The sound wave / impact detection element according to any one of [1] to [3], wherein the porous resin body includes a non-woven fabric or a woven fabric formed of a resin fiber.
[5] The sound wave / impact detection element according to [4], wherein an average fiber diameter of the fibers is 0.05 to 50 μm.
　［６］　前記多孔質樹脂体が分極処理されたものである、［１］～［５］のいずれかに記載の音波・衝撃検知素子。 [6] The sound wave / impact detection element according to any one of [1] to [5], wherein the porous resin body is subjected to polarization treatment.
　［７］　前記外力吸収シートの外力吸収率が５０％以上である、［１］～［６］のいずれかに記載の音波・衝撃検知素子。
　［８］　前記外力吸収シートの音波透過率が２０％以上である、［１］～［７］のいずれかに記載の音波・衝撃検知素子。
　［９］　前記外力吸収シートの損失弾性率が１×１０3～１×１０7Ｐａである、［１］～［８］のいずれかに記載の音波・衝撃検知素子。
　［１０］　前記外力吸収シートの厚みが０．０５～１０ｍｍである、［１］～［９］のいずれかに記載の音波・衝撃検知素子。 [7] The sound wave / impact detection element according to any one of [1] to [6], wherein the external force absorption sheet has an external force absorption rate of 50% or more.
[8] The sound wave / impact detection element according to any one of [1] to [7], wherein a sound wave transmittance of the external force absorbing sheet is 20% or more.
[9] The sound wave / impact detection element according to any one of [1] to [8], wherein the loss modulus of the external force absorbing sheet is 1 × 10 3 to 1 × 10 7 Pa.
[10] The sound wave / impact detection element according to any one of [1] to [9], wherein the external force absorbing sheet has a thickness of 0.05 to 10 mm.
　［１１］　前記多孔質樹脂体に前記外力吸収シートが積層された、［１］～［１０］のいずれかに記載の音波・衝撃検知素子。 [11] The sound wave / impact detection element according to any one of [1] to [10], wherein the external force absorbing sheet is laminated on the porous resin body.
　本発明によれば、音波・衝撃検知能および耐久性に優れる音波・衝撃検知素子を提供することができる。 According to the present invention, it is possible to provide a sound wave / impact detection element excellent in sound wave / impact detection ability and durability.
　≪音波・衝撃検知素子≫
　本発明の音波・衝撃検知素子は、音波および／または衝撃を検知する素子であり、分子および結晶構造に起因する双極子を持たない樹脂からなる多孔質樹脂体と外力吸収シートとを有する。このため、本発明の音波・衝撃検知素子は、音波・衝撃検知能および耐久性に優れる。
　本発明の音波・衝撃検知素子は、構造物の欠陥の検査、人や動物の疾患の診断、対象物に許容レベル以上の衝撃が加わったか否かの判定、測深機または探知機などの様々な分野に用いることができ、室温より高温となる環境下や、特に高い圧力のかかる環境（例：圧力が１ＭＰａ以上の環境）下で音波や衝撃を検知したい用途に好適に用いることができる。また、自動車等のエアバッグ起動判断やハードディスクなど精密機器の監視、防護用素材の開発時の試験、車両数及び車両分類計測用センサー、ゲーム機器やスポーツ機器用打撃センサーなどにも好適に用いることができる。 << Sound wave / impact detector >>
The sound wave / impact detection element of the present invention is an element for detecting sound waves and / or shocks, and includes a porous resin body made of a resin having no dipole due to a molecule and a crystal structure, and an external force absorbing sheet. For this reason, the sound wave / impact detection element of the present invention is excellent in sound wave / impact detection ability and durability.
The sound wave / impact detection element of the present invention can be used for various inspections such as inspection of structural defects, diagnosis of human or animal diseases, determination of whether or not an impact of an object has exceeded an allowable level, a sounding instrument or a detector. It can be used in the field, and can be suitably used for applications where it is desired to detect sound waves and impacts in an environment where the temperature is higher than room temperature or in an environment where a high pressure is applied (eg, an environment where the pressure is 1 MPa or more). It should also be used suitably for air bag activation judgment of automobiles, monitoring of precision equipment such as hard disks, testing during the development of protective materials, sensors for measuring the number of vehicles and vehicle classification, impact sensors for game equipment and sports equipment, etc. Can do.
　本発明の音波・衝撃検知素子は、前記多孔質樹脂体と外力吸収シートとを有すればその構造は特に制限されないが、多孔質樹脂体に外力吸収シートが積層された、特に、シート状の多孔質樹脂体に外力吸収シートが積層された積層体であることが好ましい。 The sound wave / impact detection element of the present invention is not particularly limited in its structure as long as it has the porous resin body and the external force absorbing sheet, but the external force absorbing sheet is laminated on the porous resin body. A laminate in which an external force absorbing sheet is laminated on a porous resin body is preferable.
　前記シート状の多孔質樹脂体に外力吸収シートが積層された積層体としては、シート状の多孔質樹脂体を含んでなる圧電素子の少なくとも１つの面上に外力吸収シートが積層された積層体であれば特に制限されないが、高い圧電率を保持する多孔質樹脂体を含む音波・衝撃検知素子が得られる等の点から、シート状の多孔質樹脂体を含んでなる圧電素子の表裏面（最も面積の大きい２面）上に外力吸収シートが積層された積層体、またはシート状の多孔質樹脂体を含んでなる圧電素子の全面上に外力吸収シートが積層された積層体であることが好ましい。
　高い圧電率を保持する多孔質樹脂体を含む音波・衝撃検知素子が得られ、製造容易性、コスト等の点からは、シート状の多孔質樹脂体を含んでなる圧電素子の表裏面上に外力吸収シートが積層された積層体が好ましく、より高い圧電率を保持する多孔質樹脂体を含む音波・衝撃検知素子が得られる等の点からは、シート状の多孔質樹脂体を含んでなる圧電素子の全面上に外力吸収シートが積層された積層体であることが好ましい。 As a laminate in which an external force absorbing sheet is laminated on the sheet-like porous resin body, a laminate in which an external force absorbing sheet is laminated on at least one surface of a piezoelectric element including the sheet-like porous resin body. If it is, it will not be restrict | limited especially, From the point of obtaining the sound wave and the impact detection element containing the porous resin body which hold | maintains a high piezoelectric rate, the front and back of the piezoelectric element containing a sheet-like porous resin body ( A laminate in which an external force absorbing sheet is laminated on two surfaces having the largest area), or a laminate in which an external force absorbing sheet is laminated on the entire surface of a piezoelectric element including a sheet-like porous resin body. preferable.
A sound wave / impact detecting element including a porous resin body that retains a high piezoelectric rate is obtained. From the viewpoint of ease of manufacturing, cost, etc., the front and back surfaces of the piezoelectric element including a sheet-like porous resin body are provided. A laminate in which an external force absorbing sheet is laminated is preferable. From the viewpoint of obtaining a sound wave / impact detection element including a porous resin body that retains a higher piezoelectric rate, the laminate includes a sheet-like porous resin body. A laminate in which an external force absorbing sheet is laminated on the entire surface of the piezoelectric element is preferable.
　本発明の音波・衝撃検知素子には、多孔質樹脂体および外力吸収シート以外の、従来公知の層等が存在していてもよく、例えば、前記積層体には、多孔質樹脂体と外力吸収シートとの間、多孔質樹脂体の外力吸収シートに接する側とは反対側、外力吸収シートの多孔質樹脂体に接する側とは反対側に、音波検知素子や衝撃検知素子に従来用いられてきた公知の層、例えば、電極層、表面平滑化層、保護層、絶縁層、接着層等が存在していてもよい。 In the sound wave / impact detection element of the present invention, there may be a conventionally known layer or the like other than the porous resin body and the external force absorbing sheet. For example, the laminate includes the porous resin body and the external force absorbing member. Conventionally used for sound wave detection elements and impact detection elements, between the sheet and the side of the porous resin body that is opposite to the side that contacts the external force absorption sheet, and that that is opposite to the side of the external force absorption sheet that contacts the porous resin body In addition, known layers such as an electrode layer, a surface smoothing layer, a protective layer, an insulating layer, and an adhesive layer may be present.
　前記積層体では、外力吸収シートが、多孔質樹脂体に保持された電荷が外部環境と電気的に接続して減衰することを防止する役割も果たすため、より高感度の音波・衝撃検知素子を得ることができる。 In the laminated body, the external force absorbing sheet also serves to prevent the electric charge held in the porous resin body from being electrically connected to the external environment and attenuated. Obtainable.
　前記積層体の厚さは、用いる用途等に応じて適宜調整すればよく、特に制限されないが、例えば５０μｍ～５０ｍｍであり、好ましくは１００μｍ～１０ｍｍである。 The thickness of the laminate may be appropriately adjusted according to the application to be used and is not particularly limited, but is, for example, 50 μm to 50 mm, and preferably 100 μm to 10 mm.
　＜多孔質樹脂体＞
　本発明の音波・衝撃検知素子において、前記分子および結晶構造に起因する双極子を持たない樹脂からなる多孔質樹脂体は、圧電材料として用いられ、音波・衝撃を電力に変換することで音波および／または衝撃を検知する役割を果たす。
　前記多孔質樹脂体は、微小外力への電荷応答性が高く、音波・衝撃検知能が高く、高温環境においても電荷を保持できるため、この多孔質樹脂体を用いることで、音波・衝撃検知能に優れ、可撓性が大きく、耐衝撃性および耐熱性に優れ、軽量である音波・衝撃検知素子を得ることができる。さらに、多孔質樹脂体は、薄膜化や大面積化等の任意の形状への成形性が容易であるため、所望の用途に応じて任意の形状の音波・衝撃検知素子を製造することができる。 <Porous resin body>
In the sound wave / impact detection element of the present invention, a porous resin body made of a resin having no dipole due to the molecule and crystal structure is used as a piezoelectric material, and converts sound waves / impact into electric power by converting the sound wave / impact into electric power. It plays the role of detecting impact.
The porous resin body has high charge responsiveness to minute external force, high sound wave / impact detection ability, and can retain electric charge even in a high temperature environment. It is possible to obtain a sound wave / impact detecting element that is excellent in resistance, large in flexibility, excellent in impact resistance and heat resistance, and lightweight. Furthermore, since the porous resin body can be easily formed into an arbitrary shape such as a thin film or a large area, a sound wave / impact detection element having an arbitrary shape can be manufactured according to a desired application. .
　前記多孔質樹脂体としては、電荷を保持し得る樹脂からなる構造体であることが好ましく、さらに、耐熱性を有する樹脂からなる構造体であることが好ましい。 The porous resin body is preferably a structure made of a resin capable of holding electric charge, and more preferably a structure made of a resin having heat resistance.
　前記分子および結晶構造に起因する双極子を持たない樹脂としては、分子および結晶構造が極性を示す樹脂でなければ特に制限されないが、ポリオレフィン系樹脂（ポリエチレン、ポリプロピレン、エチレンプロピレン樹脂など）、ポリエステル系樹脂（ポリエチレンエレフタラートなど）、ポリウレタン樹脂、ポリスチレン樹脂、シリコーン樹脂等の非フッ素系樹脂、および、ポリテトラフルオロエチレン（ＰＴＦＥ）、テトラフルオロエチレン－パーフルオロアルキルビニルエーテル共重合体（ＰＦＡ）、テトラフルオロエチレン－ヘキサフルオロプロピレン共重合体（ＦＥＰ）等のフッ素系樹脂などが挙げられる。 The resin having no dipole due to the molecule and crystal structure is not particularly limited as long as the molecule and crystal structure are not polar resins, but polyolefin resin (polyethylene, polypropylene, ethylene propylene resin, etc.), polyester resin Non-fluorinated resins such as resins (polyethylene terephthalate, etc.), polyurethane resins, polystyrene resins, silicone resins, etc., and polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA), tetrafluoro Examples thereof include fluorine resins such as ethylene-hexafluoropropylene copolymer (FEP).
　これらの中でも、耐熱性および耐候性等の観点から、連続使用可能温度が高く、ガラス転移点を音波・衝撃検知素子の使用温度域に持たない樹脂であることが好ましい。連続使用可能温度は、ＵＬ７４６Ｂ（ＵＬ規格）に記載の連続使用温度試験により測定でき、５０℃以上であることが好ましく、１００℃以上であることがより好ましく、２００℃以上であることがさらに好ましい。また、耐湿性の観点から、撥水性を示す樹脂であることが好ましい。
　これらの特性を有する樹脂としては、例えばポリオレフィン系樹脂、フッ素系樹脂が好ましく、フッ素系樹脂がより好ましく、ＰＴＦＥが特に好ましい。 Among these, from the viewpoints of heat resistance and weather resistance, a resin that has a high continuous usable temperature and does not have a glass transition point in the operating temperature range of the sound wave / impact detection element is preferable. The continuous useable temperature can be measured by a continuous use temperature test described in UL746B (UL standard), preferably 50 ° C or higher, more preferably 100 ° C or higher, and further preferably 200 ° C or higher. . Moreover, it is preferable that it is resin which shows water repellency from a moisture-resistant viewpoint.
As the resin having these characteristics, for example, polyolefin resin and fluorine resin are preferable, fluorine resin is more preferable, and PTFE is particularly preferable.
　特に、前記樹脂として、ＰＴＦＥを用いる場合には、耐熱性、音波・衝撃検知能および耐久性にバランスよく優れる音波・衝撃検知素子を得ることができ、該音波・衝撃検知素子は、高温／高圧環境下でも、性能や構造を維持できるため、これらの環境下、例えば、地中掘削用、石油プラント配管等の高温部材検査用の音波・衝撃検知素子として好適に使用することができる。 In particular, when PTFE is used as the resin, it is possible to obtain a sound wave / impact detection element having a good balance between heat resistance, sound wave / impact detection ability and durability. Since the performance and structure can be maintained even under the environment, it can be suitably used as a sound wave / impact detection element for inspection of high-temperature members such as for underground excavation and oil plant piping.
　前記多孔質樹脂体には、樹脂の他に、本発明の効果を損なわない範囲において、従来公知の添加剤が含まれていてもよい。
　例えば、前記多孔質樹脂体としては、高い圧電率を長期に亘って保持できるという観点から、マトリックス樹脂と電荷誘起性中空粒子（中空粒子の少なくとも一部の表面に導電性物質が付着した粒子）とを含む構造体であってもよい。 The porous resin body may contain a conventionally known additive in addition to the resin as long as the effects of the present invention are not impaired.
For example, as the porous resin body, from the viewpoint that a high piezoelectric constant can be maintained for a long period of time, matrix resin and charge-induced hollow particles (particles in which a conductive substance is attached to at least a part of the surface of the hollow particles) The structure containing these may be sufficient.
　前記多孔質樹脂体は、下記式で算出される空孔率が、好ましくは６０％以上、より好ましくは８０～９９％である。空孔率が前記範囲内である多孔質樹脂体は、電荷保持量が高いため好ましい。
　空孔率＝（樹脂の真密度－見掛けの密度）×１００／樹脂の真密度
　なお見掛けの密度は、多孔質樹脂体の重量および見掛けの体積を用いて算出される値を用いる。 The porous resin body has a porosity calculated by the following formula of preferably 60% or more, more preferably 80 to 99%. A porous resin body having a porosity in the above range is preferable because of its high charge retention amount.
Porosity = (true resin density−apparent density) × 100 / true resin density As the apparent density, a value calculated using the weight of the porous resin body and the apparent volume is used.
　前記多孔質樹脂体の形状としては、用いる用途に応じて適宜選択すればよいが、製造容易性、音波・衝撃検知性等の点から、シート状であることが好ましい。
　多孔質樹脂体がシート状である場合、その厚さは、特に制限されないが、例えば１０μｍ～１ｍｍであり、好ましくは５０μｍ～５００μｍである。 The shape of the porous resin body may be appropriately selected according to the application to be used, but is preferably a sheet from the viewpoint of ease of production, sound wave / impact detection properties, and the like.
When the porous resin body is in the form of a sheet, the thickness is not particularly limited, but is, for example, 10 μm to 1 mm, and preferably 50 μm to 500 μm.
　前記多孔質樹脂体は従来公知の種々の方法で得ることができる。例えば、前記樹脂を含む溶液の相変化を利用して細孔を形成する方法（相分離法）、細孔形成のための添加剤を樹脂に混合・分散して、成形後に除去する方法（抽出法）、前記樹脂を成形し、その後該成形体の一部分の結合を化学的に切断したり、逆に結合反応を行うことにより細孔を形成する方法（化学処理法）、樹脂を延伸し、ミクロフィブリル構造部分に微細孔を形成する方法、または、添加剤を混合分散し、延伸時に細孔を形成する方法（延伸法）、中性子線、レーザー等を照射して細孔を形成する方法（照射エッチング法）、樹脂微細片を加熱等により融着して多孔質体を形成する方法（融着法）、発泡剤を利用して細孔を形成する方法（発泡法）、前記の方法を組合せて細孔を形成する方法（複合法）、乾式紡糸、湿式紡糸、乾湿式紡糸、溶融紡糸、電界紡糸等により前記樹脂からファイバー（繊維）を形成し、該ファイバーを用いて織布または不織布を形成する方法が挙げられる。 The porous resin body can be obtained by various conventionally known methods. For example, a method of forming pores using the phase change of the solution containing the resin (phase separation method), a method of mixing and dispersing additives for pore formation in the resin and removing them after molding (extraction) Method), molding the resin, and then chemically cutting the bond of a part of the molded body, or conversely performing a binding reaction (chemical treatment method), stretching the resin, A method of forming micropores in the microfibril structure part, a method of mixing and dispersing additives and forming pores during stretching (stretching method), and a method of forming pores by irradiating neutron beams, lasers, etc. ( Irradiation etching method), a method of forming a porous body by fusing resin fine pieces by heating or the like (fusion method), a method of forming pores using a foaming agent (foaming method), Method to form pores by combining (composite method), dry spinning, wet spinning, dry Wherein spinning, melt spinning, to form a fiber (fiber) from the resin by electrospinning like, a method of forming a woven or nonwoven fabric using the fiber and the like.
　前記多孔質樹脂体としては、耐久性、長期に変形性能が維持できるという観点からは、樹脂からなるファイバーから形成された不織布または織布を含む構造体が好ましい。この構造体は、該不織布または織布を含めばよく、該不織布または織布のみからなる構造体でもよいし、該不織布または織布の表面に従来公知の層等が積層した積層体であってもよい。 The porous resin body is preferably a structure including a nonwoven fabric or a woven fabric formed from fibers made of resin from the viewpoint of durability and long-term deformation performance can be maintained. The structure may include the non-woven fabric or woven fabric, or may be a structure made of only the non-woven fabric or woven fabric, or a laminate in which a conventionally known layer is laminated on the surface of the non-woven fabric or woven fabric. Also good.
　前記ファイバーは、平均繊維径が好ましくは０．０５～５０μｍ、より好ましくは０．１～２０μｍ、さらに好ましくは０．５μｍ～５μｍである。平均繊維径が前記範囲内にあるファイバーを含む多孔質樹脂体は、繊維表面積が大きくなることで、電荷を保持する十分な空間を形成でき、薄膜にした場合でも繊維の分布均一性を高くすることができるなどの点で好ましい。 The average fiber diameter of the fiber is preferably 0.05 to 50 μm, more preferably 0.1 to 20 μm, and further preferably 0.5 μm to 5 μm. A porous resin body containing fibers having an average fiber diameter in the above range can form a sufficient space for holding electric charges by increasing the fiber surface area, and even if it is made into a thin film, the fiber distribution uniformity is increased. It is preferable in that it can be used.
　前記平均繊維径は、ファイバーを形成する条件を適宜選択することで調整することができるが、例えば、電界紡糸法によりファイバーを形成する場合には、電界紡糸の際に湿度を下げる、ノズル径を小さくする、印加電圧を大きくする、または電圧密度を大きくすることにより、得られるファイバーの平均繊維径を小さくできる傾向にある。 The average fiber diameter can be adjusted by appropriately selecting the conditions for forming the fiber.For example, when the fiber is formed by electrospinning, the humidity is reduced during electrospinning, and the nozzle diameter is adjusted. There is a tendency that the average fiber diameter of the obtained fiber can be reduced by decreasing the voltage, increasing the applied voltage, or increasing the voltage density.
　なお、前記平均繊維径は、測定対象となるファイバー（群）を走査型電子顕微鏡（ＳＥＭ）観察（倍率：１００００倍）し、得られたＳＥＭ画像から無作為に２０本のファイバーを選び、これらの各ファイバーの繊維径（長径）を測定し、この測定結果に基づいて算出される平均値である。 The average fiber diameter was determined by observing the fiber (group) to be measured with a scanning electron microscope (SEM) (magnification: 10000 times), and randomly selecting 20 fibers from the obtained SEM image. The fiber diameter (major diameter) of each fiber is measured, and is an average value calculated based on the measurement result.
　前記ファイバーの、下記式で算出される繊維径変動係数は、好ましくは０．７以下、より好ましくは０．０１～０．５である。繊維径変動係数が前記範囲内にあると、ファイバーは繊維径が均一となり、該ファイバーを用いて得られる不織布はより高い空孔率を有するため、また、電荷保持性の高い多孔質樹脂体が得られるため好ましい。
　　　繊維径変動係数＝標準偏差／平均繊維径
（なお、「標準偏差」とは、前記２０本のファイバーの繊維径の標準偏差である。） The fiber diameter variation coefficient of the fiber calculated by the following formula is preferably 0.7 or less, more preferably 0.01 to 0.5. When the fiber diameter variation coefficient is within the above range, the fiber has a uniform fiber diameter, and the nonwoven fabric obtained using the fiber has a higher porosity. Since it is obtained, it is preferable.
Fiber diameter variation coefficient = standard deviation / average fiber diameter (“standard deviation” is the standard deviation of the fiber diameters of the 20 fibers)
　前記ファイバーの繊維長は、好ましくは０．１～１０００ｍｍ、より好ましくは０．５～１００ｍｍ、さらに好ましくは１～５０ｍｍである。 The fiber length of the fiber is preferably 0.1 to 1000 mm, more preferably 0.5 to 100 mm, and still more preferably 1 to 50 mm.
　前記ファイバーの形成方法は、特に制限されないが、電界紡糸法により得られるファイバーは繊維径が小さく、また、該ファイバーを用いて得られる不織布は、中空率が高くかつ高比表面積であるため、高い圧電特性を有する多孔質樹脂体が得られる等の点から、電界紡糸法が好ましい。
　得られたファイバーを不織布状に集積または織布状に製織し、成形することで多孔質樹脂体を製造することができる。 The method for forming the fiber is not particularly limited, but the fiber obtained by the electrospinning method has a small fiber diameter, and the nonwoven fabric obtained by using the fiber has a high hollow ratio and a high specific surface area. From the viewpoint of obtaining a porous resin body having piezoelectric characteristics, the electrospinning method is preferable.
A porous resin body can be produced by accumulating the obtained fibers into a nonwoven fabric or weaving them into a woven fabric and molding them.
　［電界紡糸法］
　電界紡糸法を用いて樹脂からなるファイバーを形成する際には、例えば、前記樹脂および必要に応じて溶媒を含む紡糸液が用いられる。 [Electrospinning method]
When forming a fiber made of a resin using the electrospinning method, for example, a spinning solution containing the resin and, if necessary, a solvent is used.
　前記紡糸液中に含まれる樹脂の割合は、例えば５～１００重量％、好ましくは５～８０重量％、より好ましくは１０～７０重量％である。 The ratio of the resin contained in the spinning solution is, for example, 5 to 100% by weight, preferably 5 to 80% by weight, and more preferably 10 to 70% by weight.
　前記溶媒としては、前記樹脂を溶解または分散し得るものであれば特に限定されないが、例えば、水、ジメチルアセトアミド、ジメチルホルムアミド、テトラヒドロフラン、メチルピロリドン、キシレン、アセトン、クロロホルム、エチルベンゼン、シクロヘキサン、ベンゼン、スルホラン、メタノール、エタノール、フェノール、ピリジン、プロピレンカーボネート、アセトニトリル、トリクロロエタン、ヘキサフルオロイソプロパノール、ジエチルエーテルが挙げられる。これらの溶媒は、１種単独で用いてもよく、２種以上を組み合わせた混合溶媒としてもよい。 The solvent is not particularly limited as long as it can dissolve or disperse the resin. For example, water, dimethylacetamide, dimethylformamide, tetrahydrofuran, methylpyrrolidone, xylene, acetone, chloroform, ethylbenzene, cyclohexane, benzene, sulfolane. , Methanol, ethanol, phenol, pyridine, propylene carbonate, acetonitrile, trichloroethane, hexafluoroisopropanol, and diethyl ether. These solvents may be used alone or in combination of two or more.
　前記溶媒は、紡糸液中に例えば０～９０重量％、好ましくは１０～９０重量％、より好ましくは２５～８０重量％含まれる。 The solvent is contained in the spinning solution in an amount of, for example, 0 to 90% by weight, preferably 10 to 90% by weight, more preferably 25 to 80% by weight.
　前記紡糸液は、前記樹脂および溶媒のほかに、さらに界面活性剤、分散剤、電荷調整剤、機能性粒子、接着剤、粘度調整剤、繊維形成剤等の添加剤を含んでいてもよい。前記紡糸液は、溶媒への溶解度が低い樹脂と該溶媒を含む場合（例えば、樹脂がＰＴＦＥであり、溶媒が水である場合）、紡糸時に樹脂をファイバー状に成形させる観点から、さらに繊維形成剤を含むことが好ましい。 The spinning solution may further contain additives such as a surfactant, a dispersant, a charge adjusting agent, a functional particle, an adhesive, a viscosity adjusting agent, and a fiber forming agent in addition to the resin and the solvent. When the spinning solution contains a resin having low solubility in a solvent and the solvent (for example, when the resin is PTFE and the solvent is water), fiber formation is further performed from the viewpoint of forming the resin into a fiber shape during spinning. It is preferable that an agent is included.
　繊維形成剤としては、溶媒に対し高い溶解度を有するポリマーであることが好ましく、例えば、ポリエチレンオキサイド、ポリエチレングリコール、デキストラン、アルギン酸、キトサン、でんぷん、ポリビニルピロリドン、ポリアクリル酸、ポリメタクリル酸、ポリアクリルアミド、セルロース、ポリビニルアルコールが挙げられる。 The fiber forming agent is preferably a polymer having high solubility in a solvent, such as polyethylene oxide, polyethylene glycol, dextran, alginic acid, chitosan, starch, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, Examples thereof include cellulose and polyvinyl alcohol.
　前記繊維形成剤を使用する場合の使用量は、溶媒の粘度、樹脂の溶媒への溶解度にもよるが、紡糸液中に例えば０．１～１５重量％、好ましくは１～１０重量％である。 The amount of the fiber-forming agent used is, for example, 0.1 to 15% by weight, preferably 1 to 10% by weight in the spinning solution, although it depends on the viscosity of the solvent and the solubility of the resin in the solvent. .
　前記紡糸液は、前記樹脂、ならびに必要に応じて溶媒および添加剤を従来公知の方法で混合することにより製造できる。 The spinning solution can be produced by mixing the resin and, if necessary, a solvent and an additive by a conventionally known method.
　前記紡糸液の好ましい例としては、以下の紡糸液（１）が挙げられる。
　紡糸液（１）：ＰＴＦＥを３０～７０重量％、好ましくは３５～６０重量％含み、繊維形成剤を０．１～１０重量％、好ましくは１～７重量％含み、合計が１００重量％となるよう溶媒を含む紡糸液 Preferable examples of the spinning solution include the following spinning solution (1).
Spinning liquid (1): 30 to 70% by weight, preferably 35 to 60% by weight of PTFE, 0.1 to 10% by weight, preferably 1 to 7% by weight, and a total of 100% by weight Spinning solution containing solvent
　電界紡糸を行う際の印加電圧は、好ましくは１～１００ｋＶ、より好ましくは５～５０ｋＶ、さらに好ましくは１０～４０ｋＶである。 The applied voltage at the time of electrospinning is preferably 1 to 100 kV, more preferably 5 to 50 kV, and still more preferably 10 to 40 kV.
　電界紡糸に用いられる紡糸ノズルの先端径（外径）は、好ましくは０．１～２．０ｍｍ、より好ましくは０．２～１．６ｍｍである。 The tip diameter (outer diameter) of the spinning nozzle used for electrospinning is preferably 0.1 to 2.0 mm, more preferably 0.2 to 1.6 mm.
　より具体的には、例えば前記紡糸液（１）を用いる場合であれば、前記印加電圧は、好ましくは１０～５０ｋＶ、より好ましくは１０～４０ｋＶであり、前記の紡糸ノズルの先端径（外径）は、好ましくは０．３～１．６ｍｍである。 More specifically, for example, when the spinning solution (1) is used, the applied voltage is preferably 10 to 50 kV, more preferably 10 to 40 kV, and the tip diameter (outer diameter) of the spinning nozzle is used. ) Is preferably 0.3 to 1.6 mm.
　前記ファイバーの製造方法として、ＰＴＦＥからなるファイバーを電界紡糸法により製造する方法を例に挙げて具体的に説明する。ＰＴＦＥファイバーの製造方法としては、従来公知の製造方法を採用することができ、例えば、特表２０１２－５１５８５０号公報に記載された以下の方法が挙げられる。
　ＰＴＦＥ、繊維形成剤および溶媒を含み、少なくとも５０，０００ｃＰの粘度を有する紡糸液を提供するステップと；
　紡糸液をノズルより紡糸し静電的牽引力によりファイバー化するステップと；
　前記ファイバーをコレクター（例：巻き取りスプール）の上に集め、前駆体を形成するステップと；
　前記前駆体を焼成して前記溶媒および前記繊維形成剤を除去することによってＰＴＦＥファイバーを形成するステップとを含む方法 As a method for producing the fiber, a method for producing a fiber made of PTFE by an electrospinning method will be specifically described. As a method for producing the PTFE fiber, a conventionally known production method can be employed, and examples thereof include the following methods described in JP-T-2012-515850.
Providing a spinning solution comprising PTFE, a fiber forming agent and a solvent and having a viscosity of at least 50,000 cP;
Spinning the spinning solution from a nozzle and forming a fiber by electrostatic traction;
Collecting the fibers on a collector (eg, a take-up spool) to form a precursor;
Calcining the precursor to remove the solvent and the fiber former to form PTFE fibers.
　［不織布または織布の製造方法］
　前記ファイバーを用いて不織布を形成するには、ファイバーを形成する工程、および得られたファイバーをシート状に集積して不織布を形成する工程を、別途独立に行ってもよく、同時に行ってもよい（すなわち、ファイバーを製造しつつシート状に集積して、不織布を形成してもよい）。具体的には、例えば、電界紡糸法を用いてファイバーを形成する工程、および得られたファイバーをシート状に集積して不織布を形成する工程を同時に行ってもよいし、ファイバーを形成する工程を行った後に、湿式法により得られたファイバーをシート状に集積して不織布を形成する工程を行ってもよい。 [Production method of non-woven fabric or woven fabric]
In order to form a nonwoven fabric using the fiber, the step of forming the fiber and the step of collecting the obtained fibers into a sheet to form the nonwoven fabric may be performed separately or simultaneously. (In other words, a nonwoven fabric may be formed by collecting fibers while collecting fibers). Specifically, for example, a step of forming a fiber by using an electrospinning method and a step of collecting the obtained fibers into a sheet to form a nonwoven fabric may be simultaneously performed, or a step of forming a fiber. After performing, you may perform the process of accumulating the fiber obtained by the wet method in a sheet form, and forming a nonwoven fabric.
　前記湿式法により不織布を形成する方法としては、例えば、前記ファイバーを含有する水分散液を用い、例えばメッシュ上に前記ファイバーを堆積（集積）させてシート状に成形（抄紙）する方法が挙げられる。 Examples of a method for forming a nonwoven fabric by the wet method include a method of forming (paper making) a sheet by depositing (accumulating) the fibers on a mesh using an aqueous dispersion containing the fibers. .
　この湿式法におけるファイバーの使用量は、前記水分散液全量に対して、好ましくは０．１～１０重量％、より好ましくは０．１～５重量％である。ファイバーをこの範囲内で使用すれば、ファイバーを堆積させる工程で水を効率よく活用することができ、また、ファイバーの分散状態がよくなり、均一な湿式不織布を得ることができる。 The amount of fiber used in this wet method is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total amount of the aqueous dispersion. If the fiber is used within this range, water can be efficiently used in the process of depositing the fiber, and the dispersion state of the fiber is improved, so that a uniform wet nonwoven fabric can be obtained.
　前記水分散液には、分散状態を良好にするためにカチオン系、アニオン系、ノニオン系等の界面活性剤などからなる分散剤や油剤、また泡の発生を抑制する消泡剤等を添加してもよい。 In order to improve the dispersion state, the aqueous dispersion is added with a dispersant or an oil agent composed of a cationic, anionic, or nonionic surfactant, or an antifoaming agent that suppresses the generation of bubbles. May be.
　前記ファイバーから形成される織布は、ファイバーを形成する工程、および得られたファイバーをシート状に製織して織布を形成する工程を含む方法で製造できる。
　ファイバーをシート状に製織する方法としては、従来公知の製織方法を用いることができ、ウォータージェットルーム、エアージェットルーム、レピアルームなどの方法が挙げられる。 The woven fabric formed from the fiber can be manufactured by a method including a step of forming a fiber and a step of weaving the obtained fiber into a sheet to form a woven fabric.
As a method of weaving the fiber into a sheet, a conventionally known weaving method can be used, and methods such as a water jet room, an air jet room, and a rapier room can be used.
　前記不織布および織布の目付は、好ましくは１００ｇ／ｍ2以下、より好ましくは０．１～５０ｇ／ｍ2、さらに好ましくは０．１～２０ｇ／ｍ2である。
　前記不織布および織布の厚さは、通常１０μｍ～１ｍｍ、好ましくは５０μｍ～５００μｍである。
　前記目付および厚さは、紡糸時間を長くする、紡糸ノズル数を増やすなどにより、増大する傾向にある。 The basis weight of the nonwoven fabric and the woven fabric is preferably 100 g / m 2 or less, more preferably 0.1 to 50 g / m 2 , and still more preferably 0.1 to 20 g / m 2 .
The thickness of the nonwoven fabric and woven fabric is usually 10 μm to 1 mm, preferably 50 μm to 500 μm.
The basis weight and thickness tend to increase by increasing the spinning time or increasing the number of spinning nozzles.
　前記不織布および織布は、前記ファイバーをシート状に集積または製織したものであるが、このような不織布および織布は、単層から構成されるもの、材質や繊維径の異なる２層以上から構成されるものの何れでもよい。 The non-woven fabric and woven fabric are obtained by accumulating or weaving the fibers in a sheet shape. Such non-woven fabric and woven fabric are composed of a single layer, or composed of two or more layers having different materials and fiber diameters. Any of these may be used.
　［分極処理］
　前記多孔質樹脂体は、分極処理されたものであることが好ましい。
　前記分極処理の方法としては、従来公知の方法を用いることができ、特に制限されないが、例えば、直流電圧印加処理や交流電圧印加処理等の電圧印加処理、およびコロナ放電処理が挙げられる。 [Polarization treatment]
The porous resin body is preferably subjected to polarization treatment.
As the method for the polarization treatment, a conventionally known method can be used, and is not particularly limited, and examples thereof include voltage application processing such as DC voltage application processing and AC voltage application processing, and corona discharge processing.
　例えば、コロナ放電処理は、市販の高電圧電源と電極からなる装置を使用して行うことができる。
　放電条件は、用いる多孔質樹脂体に応じて適宜選択すればよいが、好ましい条件として、高電圧電源の電圧が－０．１～－１００ｋＶ、より好ましくは－１～－２０ｋＶ、電流が０．１～１００ｍＡ、より好ましくは１～８０ｍＡ、電極間距離が０．１～１００ｃｍ、より好ましくは１～１０ｃｍ、印加電圧が０．０１～１０．０ＭＶ／ｍ、より好ましくは０．５～２．０ＭＶ／ｍである条件が挙げられる。 For example, the corona discharge treatment can be performed using a commercially available device composed of a high voltage power source and electrodes.
The discharge conditions may be appropriately selected according to the porous resin body to be used. As preferable conditions, the voltage of the high-voltage power source is -0.1 to -100 kV, more preferably -1 to -20 kV, and the current is 0.1. 1 to 100 mA, more preferably 1 to 80 mA, the distance between the electrodes is 0.1 to 100 cm, more preferably 1 to 10 cm, and the applied voltage is 0.01 to 10.0 MV / m, more preferably 0.5 to 2. A condition of 0 MV / m is mentioned.
　前記分極処理は、多孔質樹脂体単体を分極処理してもよいが、本発明の音波・衝撃検知素子として、多孔質樹脂体と外力吸収シートや前記従来公知の層との積層体を用いる場合には、該積層体を形成した後、例えば、絶縁層を積層した後、分極処理をすることが好ましい。
　これは、多孔質樹脂体に積層される層が、多孔質樹脂体に保持された電荷が外部環境と電気的に接続して減衰するのを防止する役割を果たすため、より高感度の音波・衝撃検知素子を得ることができると考えられること、また、多孔質樹脂体と多孔質樹脂体に積層される層との間に電荷を保持し得る新たな界面を形成できる傾向にあるため、得られる音波・衝撃検知素子における多孔質樹脂体の圧電率が向上すると考えられることによる。 The polarization treatment may be performed on a porous resin body alone, but as a sound wave / impact detection element of the present invention, a laminate of a porous resin body and an external force absorbing sheet or the above-described conventionally known layer is used. For example, it is preferable to perform a polarization treatment after forming the stacked body, for example, after stacking an insulating layer.
This is because the layer laminated on the porous resin body serves to prevent the electric charge held in the porous resin body from being attenuated by being electrically connected to the external environment. It is considered that an impact detection element can be obtained, and a new interface that can hold electric charge between the porous resin body and the layer laminated on the porous resin body tends to be formed. This is because it is considered that the piezoelectricity of the porous resin body in the sound wave / impact detection element is improved.
　＜外力吸収シート＞
　前記外力吸収シート（「応力吸収シート」ともいう。）は、前記多孔質樹脂体にかかる外力を吸収し、外力により多孔質樹脂体が完全に圧縮される（空孔率が０％となる）ことを防ぐことのできるシートであれば特に制限されない。
　なお、外力とは、本発明の音波・衝撃検知素子の外部から、該素子に加わる力、例えば、圧力や衝撃のことをいう。 <External force absorbing sheet>
The external force absorbing sheet (also referred to as “stress absorbing sheet”) absorbs the external force applied to the porous resin body, and the porous resin body is completely compressed by the external force (the porosity becomes 0%). Any sheet that can prevent this is not particularly limited.
The external force means a force applied to the element from the outside of the sound wave / impact detection element of the present invention, such as pressure or impact.
　前記外力吸収シートの外力吸収率は、好ましくは５０％以上、より好ましくは８０～１００％である。
　音波吸収率が前記範囲にあることで、外力により多孔質樹脂体が完全に圧縮される（空孔率が０％となる）ことを防ぐことができるため、特に高圧下でも音波・衝撃検知能および耐久性に優れる検知素子を得ることができる。
　なお、前記外力吸収シートの外力吸収率が１００％の場合には、本発明の検知素子は、音波検知素子となる。また、前記外力吸収シートの外力吸収率が１００％未満の場合には、本発明の検知素子は、該外力吸収シートで吸収できない衝撃（外力）の存在を検知する素子であり、該外力吸収シートを透過する音波を検知する素子である。従って、例えば、予め用いる外力吸収シートの外力吸収率を測定しておくことで、対象物に外力吸収シートが吸収できる（許容レベル）衝撃（外力）以上の衝撃が加わったか否かを判定することができる。
　前記外力吸収率は、具体的には、ロードセルを用い、該ロードセルから上方の高さ５００ｍｍから３０ｇの鉄球を自由落下させた際の、外力吸収シートを用いない場合の衝撃（Ｘ：電圧値）と、ロードセル上に外力吸収シートを配置した場合の衝撃（Ｙ：電圧値）との差分から、算出［（Ｘ－Ｙ）×１００／Ｘ］することができる。 The external force absorption rate of the external force absorbing sheet is preferably 50% or more, more preferably 80 to 100%.
Since the sound absorption rate is within the above range, it is possible to prevent the porous resin body from being completely compressed by the external force (the porosity becomes 0%). In addition, a sensing element having excellent durability can be obtained.
When the external force absorption rate of the external force absorbing sheet is 100%, the detection element of the present invention is a sound wave detection element. Further, when the external force absorption rate of the external force absorbing sheet is less than 100%, the detecting element of the present invention is an element that detects the presence of an impact (external force) that cannot be absorbed by the external force absorbing sheet, and the external force absorbing sheet It is an element which detects the sound wave which permeate | transmits. Therefore, for example, by measuring the external force absorption rate of the external force absorbing sheet to be used in advance, it is determined whether or not the external force absorbing sheet can absorb the target (allowable level) impact (external force) or more. Can do.
Specifically, the external force absorption rate is the impact (X: voltage value) when an external force absorbing sheet is not used when a load cell is used and an iron ball having a height of 500 mm to 30 g above the load cell is freely dropped. ) And the impact (Y: voltage value) when the external force absorbing sheet is arranged on the load cell, [[XY] × 100 / X] can be calculated.
　前記外力吸収シートの音波透過率は、好ましくは２０％以上であり、より好ましくは５０％以上である。
　音波透過率が前記範囲にあることで、音波・衝撃検知素子が、多孔質樹脂体に外力吸収シートが積層された積層体である場合でも、外力吸収シート部分で音波が吸収されにくく、多孔質樹脂体部分で音波のほとんどを検知することができるため、高性能の音波・衝撃検知素子となり好ましい。
　前記音波透過率は、ＪＩＳ　Ａ　１４０５－１に準拠し測定することができる。 The sound transmittance of the external force absorbing sheet is preferably 20% or more, and more preferably 50% or more.
When the sound wave transmittance is in the above range, even when the sound wave / impact detection element is a laminated body in which an external force absorbing sheet is laminated on a porous resin body, sound waves are hardly absorbed by the external force absorbing sheet portion, and the porous body is porous. Since most of the sound waves can be detected by the resin body portion, it is preferable as a high-performance sound wave / impact detection element.
The sound transmittance can be measured according to JIS A 1405-1.
　前記外力吸収シートの損失弾性率は、特に制限されないが、好ましくは１×１０3～１×１０7Ｐａであり、より好ましくは１×１０4～１×１０6Ｐａである。
　損失弾性率が前記範囲にある外力吸収シートを用いることで、高感度の音波・衝撃検知素子を得ることができる。
　前記損失弾性率は、具体的には、ＪＩＳ　Ｋ　７２４４に準拠し測定することができる。 The loss elastic modulus of the external force absorbing sheet is not particularly limited, but is preferably 1 × 10 3 to 1 × 10 7 Pa, more preferably 1 × 10 4 to 1 × 10 6 Pa.
By using an external force absorbing sheet having a loss elastic modulus in the above range, a highly sensitive sound wave / impact detection element can be obtained.
Specifically, the loss elastic modulus can be measured based on JIS K 7244.
　前記外力吸収シートの体積抵抗率は、１×１０13Ω・ｃｍ以上であり、好ましくは１×１０14Ω・ｃｍ以上である。この範囲にあれば、多孔質樹脂体の長期電荷保持性向上の点で好ましい。
　体積抵抗率は、測定したい外力吸収シートを用いて二重リング電極法に基づいて測定される。 The volume resistivity of the external force absorbing sheet is 1 × 10 13 Ω · cm or more, preferably 1 × 10 14 Ω · cm or more. If it exists in this range, it is preferable at the point of the long-term charge retention improvement of a porous resin body.
The volume resistivity is measured based on the double ring electrode method using an external force absorbing sheet to be measured.
　前記外力吸収シートの厚みは、特に制限されず、外力吸収率、音波透過率および損失弾性率が前記範囲となるような厚みであることが好ましく、好ましくは０．０５～１０ｍｍであり、より好ましくは０．１～５ｍｍである。 The thickness of the external force absorbing sheet is not particularly limited, and is preferably such that the external force absorption rate, the sound wave transmittance, and the loss elastic modulus are within the above ranges, preferably 0.05 to 10 mm, and more preferably. Is 0.1 to 5 mm.
　前記外力吸収シートは、特に制限されず、外力吸収率、音波透過率および損失弾性率が前記範囲となるような材料からなるシートであることが好ましく、多孔質樹脂体との密着性に優れる等の点から有機ポリマー製シートであることが好ましく、耐熱性に優れる音波・衝撃検知素子が得られる等の点から、耐熱性有機ポリマー製シートであることがより好ましい。外力吸収特性の観点からは、外力吸収シートは、多孔質シートまたはゲル状シートであることが好ましい。 The external force absorbing sheet is not particularly limited, and is preferably a sheet made of a material having an external force absorption rate, a sound wave transmittance, and a loss elastic modulus within the above ranges, and has excellent adhesion to the porous resin body. From the point of view, a sheet made of an organic polymer is preferable, and a sheet made of a heat resistant organic polymer is more preferable from the viewpoint of obtaining a sound wave / impact detecting element excellent in heat resistance. From the viewpoint of external force absorption characteristics, the external force absorption sheet is preferably a porous sheet or a gel sheet.
　このような有機ポリマーとしては、例えば、熱硬化性のポリマーまたは熱可塑性のポリマーが挙げられる。熱硬化性のポリマーとしては、ポリイミド、エポキシ樹脂、熱硬化性ゴム（例：フッ化ビニリデン系ゴム、シリコーンゴム）、ポリウレタン、フェノール樹脂、イミド樹脂（例：ポリイミド、ポリアミドイミド、ビスマレイミド）、シリコーン樹脂等が挙げられる。熱可塑性のポリマーとしては、アクリル樹脂、メタクリル樹脂、ポリプロピレン、ポリアミド、塩化ビニル樹脂、シリコーン樹脂、フッ素樹脂（例：ＰＴＦＥ、ＰＣＴＦＥ、ＥＴＦＥ、ＰＶｄＦ、ＰＦＡ、ＦＥＰ）、ナイロン、ポリスチレン、高密度ポリエチレン、低密度ポリエチレン、ポリフェニレンスルフィド、ポリエチレンオキサイド、ポリスルホン、塩化ビニリデン等が挙げられる。外力吸収特性の観点からは、有機ポリマーとして弾性率の高い材料を用いることが好ましく、例えば熱硬化性ゴムを用いることが好ましい。 Examples of such an organic polymer include a thermosetting polymer and a thermoplastic polymer. Thermosetting polymers include polyimide, epoxy resin, thermosetting rubber (eg, vinylidene fluoride rubber, silicone rubber), polyurethane, phenolic resin, imide resin (eg, polyimide, polyamideimide, bismaleimide), silicone Examples thereof include resins. Thermoplastic polymers include acrylic resin, methacrylic resin, polypropylene, polyamide, vinyl chloride resin, silicone resin, fluororesin (eg PTFE, PCTFE, ETFE, PVdF, PFA, FEP), nylon, polystyrene, high density polyethylene, Examples thereof include low density polyethylene, polyphenylene sulfide, polyethylene oxide, polysulfone, and vinylidene chloride. From the viewpoint of external force absorption characteristics, it is preferable to use a material having a high elastic modulus as the organic polymer, for example, it is preferable to use a thermosetting rubber.
　前記外力吸収シートは、従来公知の方法により形成可能である。このような方法としては、例えば、多孔質樹脂体の少なくとも１つの面上に有機ポリマーと溶剤とを含むポリマー液を塗布・乾燥させることによりシートを形成する方法、前記ポリマー液に多孔質樹脂体を浸漬し、乾燥させることによりシートを形成する方法が挙げられる。
　また、本発明の音波・衝撃検知素子は、予め従来公知の方法で外力吸収シートを形成し、該シートを従来公知の方法で多孔質樹脂体に積層することで製造してもよい。 The external force absorbing sheet can be formed by a conventionally known method. Examples of such a method include a method of forming a sheet by applying and drying a polymer liquid containing an organic polymer and a solvent on at least one surface of the porous resin body, and a porous resin body on the polymer liquid. The method of forming a sheet | seat by immersing and drying is mentioned.
The sound wave / impact detection element of the present invention may be manufactured by forming an external force absorbing sheet in advance by a conventionally known method and laminating the sheet on a porous resin body by a conventionally known method.
　次に、本発明について実施例を示してさらに詳細に説明するが、本発明はこれらによって限定されるものではない。 Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
　［実施例１］
　特表２０１２－５１５８５０号公報に記載の電界紡糸法により、ＰＴＦＥファイバーをシート状に集積することで、多孔質樹脂体であるＰＴＦＥファイバーから形成されたシート状の不織布（厚さ０．０６ｍｍ、空孔率９５％、平均繊維径９００ｎｍ）を得、絶縁層としてＰＦＡシート（厚さ０．０２５ｍｍ、ダイキン工業株式会社製、ネオフロンＰＦＡ）を得られた不織布の上下面に重ね、３００℃で６０分間熱圧着することで多孔質樹脂体表裏面に絶縁層が形成された積層シートを作製した。この積層シートを－１５ｋＶのコロナ放電照射により分極処理した後に、得られた積層シートの両面（絶縁層上）に蒸着法で電極を形成し、さらにリード線を引き出して有機圧電素子を作製した。
　この有機圧電素子の両面（電極上）に接着テープ（住友スリーエム株式会社製、ＦＰＲ－１２）を介して、外力吸収シートとして空孔率が５０％の多孔質ＰＴＦＥシート（厚さ１ｍｍ）を積層させて、音波・衝撃検知素子を作製した。 [Example 1]
A sheet-like nonwoven fabric (thickness 0.06 mm, empty) formed from PTFE fiber, which is a porous resin body, by accumulating PTFE fibers in a sheet form by the electrospinning method described in JP-T-2012-515850. A porosity of 95%, an average fiber diameter of 900 nm) was obtained, and a PFA sheet (thickness: 0.025 mm, manufactured by Daikin Industries, Ltd., NEOFLON PFA) as an insulating layer was layered on the upper and lower surfaces of the nonwoven fabric, and 300 ° C. for 60 minutes. A laminated sheet having an insulating layer formed on the front and back surfaces of the porous resin body was produced by thermocompression bonding. After this laminated sheet was polarized by -15 kV corona discharge irradiation, electrodes were formed by vapor deposition on both surfaces (on the insulating layer) of the obtained laminated sheet, and lead wires were drawn out to produce an organic piezoelectric element.
A porous PTFE sheet (thickness 1 mm) with a porosity of 50% is laminated as an external force absorbing sheet on both surfaces (on the electrodes) of this organic piezoelectric element via an adhesive tape (FPR-12, manufactured by Sumitomo 3M Limited). Thus, a sound wave / impact detector was produced.
　作製した音波・衝撃検知素子の上面に１００ＭＰａの静圧を加えた状態で、該素子の上方５０ｃｍから１００ｇの鉄球を落下させたところ、電圧が発生し、この発生した電圧を検出した。つまり、作製した音波・衝撃検知素子により衝撃を検知することができた。 When a 100 g iron ball was dropped from 50 cm above the element in a state where a static pressure of 100 MPa was applied to the upper surface of the produced sound wave / impact detection element, a voltage was generated, and the generated voltage was detected. That is, the impact could be detected by the produced sound wave / impact detector.
　また、作成した音波・衝撃検知素子に向けて５０ｄｂの音波を照射したところ、電圧が発生し、この発生した電圧を検出した。つまり、作製した音波・衝撃検知素子により音波を検知することができた。 Further, when a 50-db sound wave was irradiated toward the created sound wave / impact detection element, a voltage was generated, and the generated voltage was detected. That is, sound waves could be detected by the produced sound wave / impact detection element.
　［実施例２］
　外力吸収シートとして、多孔質ＰＴＦＥシートの代わりにゲル状シート（株式会社タイカ製、アルファゲル）を用いた以外は実施例１と同様にして音波・衝撃検知素子を作製した。
　作製した音波・衝撃検知素子の上面に１００ＭＰａの静圧を加えた状態で、該素子の上方５０ｃｍから１００ｇの鉄球を落下させたところ、電圧が発生し、この発生した電圧を検出した。つまり、作製した音波・衝撃検知素子により衝撃を検知することができた。 [Example 2]
A sound wave / impact detection element was produced in the same manner as in Example 1 except that a gel-like sheet (manufactured by Taika Co., Ltd., Alpha Gel) was used as the external force absorbing sheet instead of the porous PTFE sheet.
When a 100 g iron ball was dropped from 50 cm above the element in a state where a static pressure of 100 MPa was applied to the upper surface of the produced sound wave / impact detection element, a voltage was generated, and the generated voltage was detected. That is, the impact could be detected by the produced sound wave / impact detector.
　［比較例１］
　外力吸収シートを設けなかった以外は実施例１と同様に素子を作製した。
　作製した素子の上面に１００ＭＰａの静圧を加えた状態で、該素子の上方５０ｃｍから１００ｇの鉄球を落下させたところ、電圧を検出することができなかった。つまり、作製した素子では衝撃を検知することができなかった。 [Comparative Example 1]
A device was produced in the same manner as in Example 1 except that the external force absorbing sheet was not provided.
When a 100 g iron ball was dropped from 50 cm above the element in a state where a static pressure of 100 MPa was applied to the upper surface of the manufactured element, no voltage could be detected. That is, the manufactured element could not detect the impact.

Claims (11)

  1. 　分子および結晶構造に起因する双極子をもたない樹脂からなる多孔質樹脂体と、外力吸収シートとを有する音波・衝撃検知素子。 A sound wave / impact detection element having a porous resin body made of a resin having no dipole due to a molecule and a crystal structure, and an external force absorbing sheet.
  2. 　前記多孔質樹脂体の空孔率が６０％以上である、請求項１に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to claim 1, wherein the porosity of the porous resin body is 60% or more.
  3. 　前記樹脂がポリテトラフルオロエチレンである、請求項１または２に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to claim 1 or 2, wherein the resin is polytetrafluoroethylene.
  4. 　前記多孔質樹脂体が、樹脂からなるファイバーから形成された不織布または織布を含む、請求項１～３のいずれか１項に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to any one of claims 1 to 3, wherein the porous resin body includes a nonwoven fabric or a woven fabric formed from fibers made of resin.
  5. 　前記ファイバーの平均繊維径が０．０５～５０μｍである、請求項４に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to claim 4, wherein an average fiber diameter of the fibers is 0.05 to 50 µm.
  6. 　前記多孔質樹脂体が分極処理されたものである、請求項１～５のいずれか１項に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to any one of claims 1 to 5, wherein the porous resin body is subjected to polarization treatment.
  7. 　前記外力吸収シートの外力吸収率が５０％以上である、請求項１～６のいずれか１項に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to any one of claims 1 to 6, wherein the external force absorption sheet has an external force absorption rate of 50% or more.
  8. 　前記外力吸収シートの音波透過率が２０％以上である、請求項１～７のいずれか１項に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to any one of claims 1 to 7, wherein a sound wave transmittance of the external force absorbing sheet is 20% or more.
  9. 　前記外力吸収シートの損失弾性率が１×１０3～１×１０7Ｐａである、請求項１～８のいずれか１項に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to any one of claims 1 to 8, wherein a loss elastic modulus of the external force absorbing sheet is 1 × 10 3 to 1 × 10 7 Pa.
  10. 　前記外力吸収シートの厚みが０．０５～１０ｍｍである、請求項１～９のいずれか１項に記載の音波・衝撃検知素子。 10. The sound wave / impact detection element according to claim 1, wherein the external force absorbing sheet has a thickness of 0.05 to 10 mm.
  11. 　前記多孔質樹脂体に前記外力吸収シートが積層された、請求項１～１０のいずれか１項に記載の音波・衝撃検知素子。 The sound wave / impact detection element according to any one of claims 1 to 10, wherein the external force absorbing sheet is laminated on the porous resin body.
PCT/JP2015/063093 2014-05-01 2015-05-01 Sound wave and shock detection element WO2015167013A1 (en)

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