WO2023042892A1 - 有機圧電フィルム - Google Patents
有機圧電フィルム Download PDFInfo
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- WO2023042892A1 WO2023042892A1 PCT/JP2022/034620 JP2022034620W WO2023042892A1 WO 2023042892 A1 WO2023042892 A1 WO 2023042892A1 JP 2022034620 W JP2022034620 W JP 2022034620W WO 2023042892 A1 WO2023042892 A1 WO 2023042892A1
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- film
- organic piezoelectric
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Images
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- 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
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
- C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08L27/16—Homopolymers or copolymers or vinylidene fluoride
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
- C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08L27/18—Homopolymers or copolymers or tetrafluoroethene
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
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- 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
- H10N30/01—Manufacture or treatment
- H10N30/04—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
- H10N30/045—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning by polarising
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- H—ELECTRICITY
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- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/09—Forming piezoelectric or electrostrictive materials
- H10N30/092—Forming composite materials
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- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/09—Forming piezoelectric or electrostrictive materials
- H10N30/098—Forming organic materials
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- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/704—Piezoelectric or electrostrictive devices based on piezoelectric or electrostrictive films or coatings
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- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/852—Composite materials, e.g. having 1-3 or 2-2 type connectivity
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- C08L2201/00—Properties
- C08L2201/10—Transparent films; Clear coatings; Transparent materials
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- C08L2203/00—Applications
- C08L2203/20—Applications use in electrical or conductive gadgets
Definitions
- the present disclosure relates to organic piezoelectric films.
- An organic piezoelectric film is a film that is formed from an organic polymer and has piezoelectricity (the property of converting an applied force into a voltage or the property of converting an applied voltage into a force).
- Organic piezoelectric films are used in a variety of applications that utilize piezoelectricity [e.g., sensors, actuators, touch panels, haptic devices (devices that have a function of giving feedback to the user), vibration power generators, speakers, and microphones].
- piezoelectricity e.g., sensors, actuators, touch panels, haptic devices (devices that have a function of giving feedback to the user), vibration power generators, speakers, and microphones.
- sufficient light transmittance is required when an organic piezoelectric film is arranged on a display.
- low retardation is required in order to avoid interference with display-constituting members (eg, polarizing plate
- PVDF polyvinylidene fluoride
- the uniaxially stretched PVDF film has large in-plane variations in film thickness and piezoelectricity, and high retardation.
- piezoelectricity and transparency since there is a trade-off relationship between piezoelectricity and transparency, it is difficult to obtain a film having both high piezoelectricity and high transparency. In the case of , it is even more difficult to achieve both high piezoelectricity and high transparency.
- both the piezoelectricity and the transparency decrease, so it is even more difficult to achieve both high piezoelectricity and high transparency.
- An object of the present disclosure is to provide an organic piezoelectric film having high piezoelectricity and high transparency.
- Section 1 Total light transmittance is 90% or more, The internal haze value per unit film thickness is 0.2%/ ⁇ m or less, The piezoelectric constant d33 after heating at 110° C. for 10 minutes is 10 pC/N or more.
- Section 2. Item 2. The organic piezoelectric film according to item 1, comprising a vinylidene fluoride copolymer film.
- Item 3. Item 3. The organic polymer according to item 2, wherein the vinylidene fluoride-based copolymer is at least one selected from the group consisting of vinylidene fluoride/tetrafluoroethylene copolymers and vinylidene fluoride/trifluoroethylene copolymers.
- Item 4 The organic piezoelectric film according to Item 2 or 3, wherein the vinylidene fluoride-based copolymer has a composition ratio of vinylidene fluoride in the range of 60 to 85 mol %.
- Item 5. The organic piezoelectric film according to any one of Items 1 to 4, which has a thickness of 10 nm to 1000 ⁇ m.
- Item 6. The organic piezoelectric film according to any one of Items 1 to 5, which has a retardation of 500 nm or less.
- Item 7. The organic piezoelectric film according to any one of Items 1 to 6, which has a YI value of 4 or less.
- Item 8. Item 8.
- the organic piezoelectric film according to any one of Items 1 to 7, which has a residual polarization amount of 40 mC/m 2 or more.
- Item 9 In the X-ray diffraction pattern obtained when the film sample is directly placed on the sample holder provided with the opening and the X-ray diffraction measurement is performed over the range where the diffraction angle 2 ⁇ is 10 to 40 °, A straight line connecting the diffraction intensity at a diffraction angle 2 ⁇ of 10° and the diffraction intensity at a diffraction angle 2 ⁇ of 25° is set as a baseline, and the area surrounded by the baseline and the diffraction intensity curve is divided into 2 by profile fitting.
- Organic piezoelectric film Item 11. Item 11. The organic piezoelectric film according to Item 10, having an average crystal length of 450 nm or less. Item 12. In the X-ray diffraction pattern obtained when the film sample is directly placed on the sample holder provided with the opening and the X-ray diffraction measurement is performed over the range where the diffraction angle 2 ⁇ is 10 to 40 °, A straight line connecting the diffraction intensity at a diffraction angle 2 ⁇ of 10° and the diffraction intensity at a diffraction angle 2 ⁇ of 25° is set as a baseline, and the area surrounded by the baseline and the diffraction intensity curve is divided into 2 by profile fitting.
- Step A of preparing a non-stretched and non-polarized vinylidene fluoride polymer film by a casting method; Step B of subjecting the non-stretched and non-polarized vinylidene fluoride polymer film to polarization treatment; and Step C of heat-treating the unstretched vinylidene fluoride polymer film at an arbitrary time in step B.
- a method for producing an organic piezoelectric film comprising A method for producing an organic piezoelectric film, wherein step A includes step A3 of heating within a range of (T-10)°C to (T+5)°C, where T° is the melting point of the vinylidene fluoride polymer.
- an organic piezoelectric film having high piezoelectricity and high transparency is provided. Furthermore, an organic piezoelectric film is provided that has high piezoelectricity and high transparency even after heating (eg, heating at 110° C. for 10 minutes).
- FIG. 1 is a schematic diagram showing an outline of a manufacturing apparatus used for manufacturing piezoelectric films of Examples.
- FIG. FIG. 3 is a diagram showing scanning electron microscope images of Example 1 and Comparative Example 3;
- room temperature can mean a temperature within the range of 10-40°C.
- C nm (where n and m are each an integer and n ⁇ m) means that the number of carbon atoms is n or more and m Represents the following.
- the organic piezoelectric film of the present disclosure contains an organic piezoelectric polymer.
- the piezoelectric polymer include, but are not limited to, vinylidene fluoride-based polymer, vinylidene cyanide-based polymer, odd-chain nylon, and polylactic acid.
- the piezoelectric polymer may be used alone or in combination of two or more.
- a vinylidene fluoride polymer is preferable as the piezoelectric polymer.
- the vinylidene fluoride polymer is preferably a polarized vinylidene fluoride polymer.
- the term "polarized" means that the surface is charged. That is, the polarized vinylidene fluoride-based polymer can be electret, piezoelectric, or ferroelectric.
- a vinylidene fluoride polymer is a polymer containing at least vinylidene fluoride (VDF) as a polymerization component (monomer).
- the vinylidene fluoride-based polymer may be a vinylidene fluoride homopolymer (polyvinylidene fluoride), or a copolymer (fluoride) of vinylidene fluoride and one or more monomers copolymerizable with vinylidene fluoride. vinylidene-based copolymer).
- the one or more monomers copolymerizable with vinylidene fluoride may be one or more halogen-containing monomers, one or more halogen-free monomers, or combinations thereof. .
- halogen-containing monomers examples include vinyl fluoride (VF), trifluoroethylene (TrFE), tetrafluoroethylene (TFE), hexafluoropropene (HFP), 1-chloro-1-fluoroethylene (1,1-CFE ), 1-chloro-2-fluoroethylene (1,2-CFE), 1-chloro-2,2-difluoroethylene (CDFE), chlorotrifluoroethylene (CTFE), trifluorovinyl monomer, 1,1,2 -trifluorobutene-4-bromo-1-butene, 1,1,2-trifluorobutene-4-silane-1-butene, perfluoropropyl vinyl ether (PPVE), perfluoroacrylate, 2,2,2-trifluoro fluorine-containing monomers such as ethyl acrylate and 2-(perfluorohexyl)ethyl acrylate);
- Halogen-free monomers include, for example, ⁇ -olefins (e.g. ethylene, propylene); unsaturated dicarboxylic acids or derivatives thereof (e.g. maleic acid, maleic anhydride); vinyl ethers (e.g. ethyl vinyl ether); allyl ethers (e.g. : allyl glycidyl ether); vinyl ester (eg, vinyl acetate); acrylic acid or its ester; methacrylic acid or its ester, and the like.
- ⁇ -olefins e.g. ethylene, propylene
- unsaturated dicarboxylic acids or derivatives thereof e.g. maleic acid, maleic anhydride
- vinyl ethers e.g. ethyl vinyl ether
- allyl ethers e.g. : allyl glycidyl ether
- vinyl ester eg, vinyl acetate
- acrylic acid or its ester methacryl
- the vinylidene fluoride polymer is preferably a copolymer (vinylidene fluoride copolymer) of vinylidene fluoride and one or more monomers copolymerizable with vinylidene fluoride.
- the lower limit of the compositional ratio of vinylidene fluoride in the copolymer [molar ratio of repeating units ( --CH.sub.2 -- CF.sub.2-- ) derived from vinylidene fluoride to all repeating units] is preferably 65 mol % or 66 mol. %, 67 mol %, 68 mol %, 69 mol %, 70 mol %, 71 mol %, 72 mol %, or 73 mol %.
- the upper limit of the composition ratio of vinylidene fluoride in the copolymer is preferably 85 mol %, 84 mol %, 83 mol %, or 82 mol %.
- the copolymer is preferably at least one selected from the group consisting of vinylidene fluoride/trifluoroethylene copolymers and vinylidene fluoride/tetrafluoroethylene copolymers.
- the composition ratio of vinylidene fluoride and trifluoroethylene [repeating units derived from vinylidene fluoride ( --CH.sub.2 -- CF.sub.2-- ) and repeating units derived from trifluoroethylene
- the lower limit of the molar ratio with (-CF 2 -CHF-)] is preferably 65/35, more preferably 70/30, still more preferably 73/27.
- the upper limit of the composition ratio is preferably 85/15, more preferably 82/18.
- the composition ratio is preferably within the range of 65/35 to 85/15, more preferably within the range of 70/30 to 85/15, and even more preferably within the range of 73/27 to 82/18.
- the vinylidene fluoride/trifluoroethylene copolymer may be a copolymer in which only vinylidene fluoride and trifluoroethylene are polymerized components, vinylidene fluoride, trifluoroethylene, and one or more other monomers.
- the one or more other monomers can be selected, for example, from the group consisting of the monomers exemplified above as "one or more monomers copolymerizable with vinylidene fluoride" (excluding trifluoroethylene). .
- the lower limit of the composition ratio of the one or more other monomers is, for example, 0.01 mol %, 0.05 mol %, or 0.1 mol %.
- the upper limit of the composition ratio of the one or more other monomers is, for example, 10 mol %, 5 mol %, or 1 mol %.
- the composition ratio of vinylidene fluoride and tetrafluoroethylene [repeating units derived from vinylidene fluoride ( --CH.sub.2 -- CF.sub.2-- ) and repeating units derived from tetrafluoroethylene
- the lower limit of the molar ratio to (—CF 2 —CF 2 —)] is preferably 65/35, more preferably 66/34, still more preferably 67/33.
- the upper limit of the composition ratio is preferably 85/15, more preferably 82/18, still more preferably 80/20.
- the composition ratio is preferably within the range of 65/35 to 85/15, more preferably within the range of 66/34 to 82/18, and even more preferably within the range of 67/33 to 80/20.
- the vinylidene fluoride/tetrafluoroethylene copolymer may be a copolymer in which only vinylidene fluoride and tetrafluoroethylene are polymerized components, vinylidene fluoride, tetrafluoroethylene, and one or more other monomers.
- the one or more other monomers can be selected, for example, from the group consisting of the monomers exemplified above as "one or more monomers copolymerizable with vinylidene fluoride" (excluding tetrafluoroethylene). .
- the lower limit of the composition ratio of the one or more other monomers is, for example, 0.01 mol %, 0.05 mol %, or 0.1 mol %.
- the upper limit of the composition ratio of the one or more other monomers is, for example, 10 mol %, 5 mol %, or 1 mol %.
- the piezoelectric polymer preferably has a weight average molecular weight (Mw) of 50,000 or more and 2,000,000 or less.
- Mw weight average molecular weight
- a thickness within the above range is preferable in terms of excellent workability and excellent piezoelectricity.
- the weight average molecular weight is 100,000 or more and 2,000,000 or less.
- the lower limit of the weight average molecular weight is more preferably 200,000 or more, still more preferably 300,000 or more, and most preferably 600,000 or more.
- the upper limit of the weight average molecular weight is more preferably 1,900,000 or less, still more preferably 1,800,000 or less, and most preferably 1,100,000 or less.
- the weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC), for example. Specifically, the molecular weight can be calculated on the basis of standard polystyrene based on the results of measurement by the GPC method under the following conditions.
- GPC equipment TOSOH AS-8010, CO-8020 and SIMADZURID-10A
- Developing solvent dimethylformamide [DMF]
- Sample concentration 0.05% by mass
- the melting point of the piezoelectric polymer is not particularly limited as long as it is a temperature that does not degrade the base material. It may be 190° C. or less, 180° C. or less, 170° C. or less, or 160° C. or less.
- the melting point is measured by differential scanning calorimetry (DSC), for example, according to the plastic transition temperature measurement method (JIS K7121), as the maximum value in the heat of fusion curve obtained when the temperature is raised at a rate of 10 ° C./min. can do.
- the lower limit of the content of the piezoelectric polymer in the organic piezoelectric film of the present disclosure is, for example, 10% by mass, 20% by mass, 30% by mass, 40% by mass, 50% by mass, 60% by mass, or 70% by mass, It is preferably 80% by mass, more preferably 85% by mass, and still more preferably 90% by mass.
- the upper limit of the content is not particularly limited, and is, for example, 100% by mass or 99% by mass.
- the organic piezoelectric film of the present disclosure can further contain polymers other than piezoelectric polymers.
- polymers other than piezoelectric polymers include polycarbonate, polyester (e.g. polyethylene terephthalate, polyethylene naphthalate), polyamide, silicone resin, polyether, polyvinyl acetate, acrylic resin, methacrylic resin, and polyolefin (e.g. polyethylene, polypropylene) and the like.
- the content of the polymer other than the piezoelectric polymer is not particularly limited. 10 parts by mass or less, 5 parts by mass or less, or 1 part by mass or less.
- the organic piezoelectric film of the present disclosure may be a film made of a piezoelectric polymer (or a piezoelectric polymer and a polymer other than a piezoelectric polymer), or a film containing a piezoelectric polymer and an additive.
- Examples of the latter films include films in which inorganics are dispersed in the piezoelectric polymer.
- additives include fillers (e.g., inorganic oxide particles), affinity improvers, heat stabilizers, UV absorbers, pigments, and combinations of one or more of these.
- fillers e.g., inorganic oxide particles
- affinity improvers e.g., heat stabilizers
- UV absorbers e.g., UV absorbers
- pigments e.g., pigments, and combinations of one or more of these.
- examples include inorganic oxide particles and combinations of inorganic oxide particles and affinity enhancers.
- Suitable examples of inorganic oxide particles include at least one selected from the group consisting of inorganic oxide particles (B1) to (B3) below.
- (B1) is particles of an oxide of a metal element of Groups 2, 3, 4, 12 or 13 of the periodic table, or inorganic oxide composite particles thereof.
- metal elements include Be, Mg, Ca, Sr, Ba, Y, Ti, Zr, Zn, and Al.
- Suitable examples of (B1) include particles of oxides of Be, Al, Mg, Y, and Zr. The particles are generally used, inexpensive, and high in volume resistivity. More preferred examples of (B1) include particles of at least one inorganic oxide selected from the group consisting of Al2O3 , MgO, ZrO2 , Y2O3 , BeO, and MgO.Al2O3 . contain.
- the particles are preferable because they have a high volume resistivity. More preferred examples of (B1) include Al 2 O 3 with a ⁇ -type crystal structure. The particles are preferable because they have a large specific surface area and good dispersibility in the piezoelectric polymer.
- [Inorganic oxide particles (B2)] (B2) has the formula: M 1 a1 M 2 b1 O c1 (wherein M 1 is a Group 2 metal element; M 2 is a Group 4 metal element; a1 is within the range of 0.9 to 1.1; b1 is within the range of 0.9 to 1.1 Yes; c1 is in the range of 2.8 to 3.2; M 1 and M 2 can each be one or more metal elements) It is a particle of an inorganic composite oxide represented by. Suitable examples of the Group 2 metal elements include Mg, Ca, Sr and Ba. Preferred examples of the Group 4 metal elements include Ti and Zr.
- Preferred examples of (B2) include particles of at least one inorganic oxide selected from the group consisting of BaTiO3 , SrTiO3 , CaTiO3 , MgTiO3 , BaZrO3 , SrZrO3 , CaZrO3 , and MgZrO3 . do.
- the particles are preferable because they have a high volume resistivity.
- [Inorganic oxide particles (B3)] is inorganic oxide composite particles of an oxide of a metal element of Groups 2, 3, 4, 12, or 13 of the periodic table and silicon oxide.
- metal elements include Be, Mg, Ca, Sr, Ba, Y, Ti, Zr, Zn, and Al.
- Specific examples of (B3) include particles of at least one inorganic oxide selected from the group consisting of 3A12O3.2SiO2 , 2MgO.SiO2 , ZrO2.SiO2 , and MgO.SiO2 . .
- the inorganic oxide particles do not necessarily have high dielectric properties, and can be appropriately selected depending on the application of the organic piezoelectric film.
- the volume resistivity can be improved by using general-purpose and inexpensive inorganic oxide particles [eg (B1), especially Al 2 O 3 particles and MgO particles].
- the relative permittivity (1 kHz, 25° C.) of one of these inorganic oxide particles (B1) is usually less than 100, preferably 10 or less.
- ferroelectric (example: dielectric constant (1 kHz, 25 ° C.) of 100 or more] inorganic oxide particles [example: (B2) and (B3)] are used for the purpose of improving the dielectric constant.
- inorganic materials constituting ferroelectric inorganic oxide particles include, but are not limited to, composite metal oxides, their composites, solid solutions, and sol-gel bodies.
- the dielectric constant (25° C., 1 kHz) of the inorganic oxide particles is preferably in the range of 10 or more. From the viewpoint of increasing the dielectric constant of the organic piezoelectric film, the relative dielectric constant is preferably 100 or more, more preferably 300 or more. Although the upper limit of the dielectric constant is not particularly limited, it is usually about 3,000.
- the average primary particle size is preferably 800 nm or less, more preferably 500 nm or less, and still more preferably 300 nm or less.
- the average primary particle size is preferably 10 nm or more, more preferably 20 nm or more, and still more preferably 50 nm or more, from the viewpoints of production difficulty, uniform dispersion difficulty, and cost.
- the average primary particle size of the inorganic oxide particles is calculated using a laser diffraction/scattering particle size distribution analyzer LA-920 (trade name) (Horiba Ltd.) or its equivalent.
- the organic piezoelectric film preferably does not contain inorganic oxide particles from the viewpoint of transparency. It can be contained in the range of 300 parts by mass, more preferably 0.1 to 100 parts by mass.
- the lower limit of the content is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, and still more preferably 1 part by mass from the viewpoint of improving electrical insulation.
- the upper limit of the content is preferably 200 mass, more preferably 200 mass, from the viewpoint of uniformly dispersing the inorganic oxide particles in the piezoelectric polymer and preventing a decrease in electrical insulation (withstanding voltage) and a decrease in tensile strength. is 150 parts by mass, more preferably 100 parts by mass.
- the organic piezoelectric film contains inorganic oxide particles
- it can further contain an affinity improver.
- the affinity enhancer increases the affinity between the inorganic oxide particles and the piezoelectric polymer, disperses the inorganic oxide particles uniformly in the piezoelectric polymer, and firmly bonds the inorganic oxide particles and the piezoelectric polymer. , the generation of voids can be suppressed, and the dielectric constant can be increased.
- affinity improvers include coupling agents, surfactants, and epoxy group-containing compounds.
- Examples of coupling agents include organic titanium compounds, organic silane compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorus compounds.
- organotitanium compounds include organotitanium coupling agents (eg, alkoxy titanium, titanium chelates, titanium acylates), and specific examples thereof include tetraisopropyl titanate, titanium isopropoxy octylene glycolate, diisopropoxy - Bis(acetylacetonato)titanium, diisopropoxytitanium diisostearate, tetraisopropylbis(dioctylphosphite)titanate, and isopropyltri(n-aminoethyl-aminoethyl)titanate, tetra(2,2-diallyloxy) Methyl-1-butyl)bis(di-tridecyl)phosphite titanate.
- organotitanium coupling agents eg, alkoxy titanium, titanium chelates, titanium acylates
- specific examples thereof include tetraisopropyl titanate
- the organic silane compound may be of a high-molecular type or a low-molecular type, examples of which include alkoxysilanes (e.g., monoalkoxysilanes, dialkoxysilanes, trialkoxysilanes, tetraalkoxysilanes), vinylsilanes, Includes epoxysilanes, aminosilanes, metachloroxysilanes, and mercaptosilanes. When alkoxysilane is used, hydrolysis can further improve volume resistivity (improvement in electrical insulation), which is an effect of surface treatment.
- alkoxysilanes e.g., monoalkoxysilanes, dialkoxysilanes, trialkoxysilanes, tetraalkoxysilanes
- vinylsilanes Includes epoxysilanes, aminosilanes, metachloroxysilanes, and mercaptosilanes.
- hydrolysis can further improve volume resistivity (impro
- organic zirconium compounds include alkoxyzirconium and zirconium chelates.
- organoaluminum compounds include alkoxyaluminums and aluminum chelates.
- organic phosphorus compounds include phosphites, phosphates, and phosphate chelates.
- the surfactant as an affinity improver may be of the high molecular type or the low molecular type, but from the viewpoint of thermal stability, the high molecular type is preferred.
- surfactants include nonionic surfactants, anionic surfactants, and cationic surfactants.
- nonionic surfactants include polyether derivatives, polyvinylpyrrolidone derivatives, and alcohol derivatives, and preferred examples thereof include polyether derivatives because of their good affinity with inorganic oxide particles. contain.
- anionic surfactants include polymers containing sulfonic acids and carboxylic acids and salts thereof, and a preferred example thereof is acrylic acid because of its good affinity with piezoelectric polymers. It includes derivative-based polymers and methacrylic acid derivative-based polymers.
- cationic surfactants include amine compounds, compounds having nitrogen-containing complex rings (eg imidazoline), and halogenated salts thereof.
- the epoxy group-containing compound as an affinity improver may be a low-molecular-weight compound or a high-molecular-weight compound.
- Specific examples include epoxy compounds and glycidyl compounds, and preferred examples thereof include , from the viewpoint of affinity with the piezoelectric polymer, it includes a low-molecular-weight compound having one epoxy group.
- epoxy group-containing compounds are represented by the following formula: (In the formula, R represents a hydrogen atom, a methyl group, a hydrocarbon group having 2 to 10 carbon atoms which may be interposed by an oxygen atom or a nitrogen atom, or an optionally substituted aromatic ring group. l is 0 or 1, m represents 0 or 1, and n represents an integer of 0 to 10.) The compound represented by is included.
- Examples of compounds represented by the above formula include compounds having a ketone group or an ester group, and more specifically include compounds represented by the following formula:
- the content of the affinity improver is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of the inorganic oxide particles in terms of uniform dispersion and high relative dielectric constant of the resulting organic piezoelectric film. , more preferably 0.1 to 25 parts by mass, and still more preferably 1 to 20 parts by mass.
- the organic piezoelectric film is preferably a non-stretched film.
- the organic piezoelectric film is a cast film.
- the organic piezoelectric film preferably has the following physical properties.
- each physical property means a physical property measured without heating as a pretreatment before measurement, and the description "after heating at 110 ° C. for 10 minutes" is added. , means the physical properties measured after heating at 110° C. for 10 minutes as a pretreatment.
- the object to be heated at 110° C. for 10 minutes can be the organic piezoelectric film after production. It targets organic piezoelectric films.
- the organic piezoelectric film preferably has at least the following total light transmittance, the following internal haze value per unit film thickness, and the following piezoelectric constant d of 33 after heating at 110° C. for 10 minutes. .
- the organic piezoelectric film preferably has at least the following crystal size (especially crystal average length) and the following piezoelectric constant d 33 after heating at 110° C. for 10 minutes.
- the organic piezoelectric film preferably has at least the rate of change of the internal haze value per unit thickness and the rate of change of the piezoelectric constant d33 below.
- the organic piezoelectric film preferably further has at least one physical property selected from the group consisting of the film thickness below, the retardation below, the YI value below, the amount of residual polarization below, and the degree of crystallinity below.
- the organic piezoelectric film preferably further has at least one physical property selected from the group consisting of the following variation coefficient of piezoelectric constant d33 , the following variation coefficient of film thickness, and the following area.
- Total light transmittance ⁇ Method for determining total light transmittance>
- total light transmittance can be measured using a haze meter NDH-7000SP (product name, Nippon Denshoku Industries Co., Ltd.) or its equivalent in accordance with JIS K-7361.
- the lower limit of the total light transmittance is preferably 90%, more preferably 91%, still more preferably 92%, and particularly preferably 93%.
- the lower limit of the total light transmittance after heating at 110° C. for 10 minutes can also be set to the same value.
- the upper limit of the total light transmittance is not particularly limited, it can be, for example, 99.99%, 99.9%, or 99%.
- the upper limit of the total light transmittance after heating at 110° C. for 10 minutes can also be set to the same value.
- the total light transmittance is preferably 90% or more (eg, within the range of 90 to 99.99%), more preferably 91% or more (eg, within the range of 91 to 99.99%), still more preferably 92%. above (eg, within the range of 92 to 99.99%).
- the range of total light transmittance after heating at 110° C. for 10 minutes can also be set to the same range.
- Internal Haze Value ⁇ Method for Determining Internal Haze Value>
- the "internal haze value” (inner haze) is based on JIS K-7361, and the haze (HAZE, Turbidity) In the test, water is put into a glass cell, a film is inserted therein, and the haze value is measured.
- the upper limit of the internal haze value is preferably 6%, more preferably 5.5%, and even more preferably 5%. Moreover, the upper limit of the internal haze value can be set to a lower value, for example, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, or 1%. From the viewpoint of transparency, the upper limit of the internal haze value after heating at 110° C. for 10 minutes is preferably 7%, more preferably 6.5%, and even more preferably 6%. Further, the upper limit of the internal haze value after heating at 110°C for 10 minutes can be set to a lower value, for example, 5.5%, 5%, 4.5%, 4%, 3.5%.
- the lower limit of the internal haze value is not particularly limited, but can be, for example, 0.01%, 0.05%, or 0.1%.
- the lower limit of the internal haze value after heating at 110° C. for 10 minutes can also be set to the same value.
- the internal haze value is preferably 6% or less (eg, within the range of 0.01 to 6%), more preferably 5.5% or less (eg, within the range of 0.01 to 5.5%), still more preferably is 5% or less (eg, within the range of 0.01 to 5%).
- the "change rate of internal haze value" is obtained by the formula: ((internal haze value after heating at 110 ° C. for 10 minutes) - (internal haze value)) / (internal haze value) x 100 means the absolute value of the value.
- the upper limit of the internal haze value change rate is preferably 140%, more preferably 120%, still more preferably 100%, and even more preferably 90%.
- the upper limit of the internal haze value change rate can be set to a lower value, for example, 80%, 70%, 60%, or 50%.
- the lower limit of the internal haze value change rate is not particularly limited, but is, for example, 1%, 2%, 3%, 4%, or 5%.
- the change rate of the internal haze value is preferably 140% or less (eg, within the range of 1 to 140%), more preferably 120% or less (eg, within the range of 1 to 120%), further preferably 100% or less ( Example: within the range of 1 to 100%).
- Ratio of internal haze value [%]/film thickness [ ⁇ m] The upper limit of the ratio of internal haze value [%]/film thickness [ ⁇ m] is preferably 0.2, more preferably 0.15, from the viewpoint of transparency. , more preferably 0.1, and particularly preferably 0.05.
- the upper limit of the ratio of internal haze value [%]/film thickness [ ⁇ m] after heating at 110° C. for 10 minutes can also be set to the same value.
- the lower limit of the ratio of internal haze value [%]/film thickness [ ⁇ m] is not particularly limited, it can be, for example, 0.0001, 0.0005, 0.001, or 0.005.
- the ratio of internal haze value [%] / film thickness [ ⁇ m] is preferably 0.2 or less (eg: within the range of 0.0001 to 0.2), more preferably 0.15 or less (eg: 0.0001 to 0.15), more preferably 0.1 or less (eg, 0.0001 to 0.1).
- the range of ratio of internal haze value [%]/film thickness [ ⁇ m] after heating at 110° C. for 10 minutes can also be set within the same range. Even if the ratio is within such a range, high piezoelectricity can be exhibited.
- Rate of change in ratio of internal haze value [%]/film thickness [ ⁇ m] is defined as r , means the absolute value of the value obtained by the formula: ((r value after heating at 110° C. for 10 minutes) ⁇ (r value))/(r value) ⁇ 100.
- the upper limit of the r-value change rate is preferably 140%, more preferably 120%, still more preferably 100%, and even more preferably 90%.
- the upper limit of the rate of change of the r-value can be set to a lower value, such as 80%, 70%, 60%, or 50%.
- the lower limit of the r-value change rate is not particularly limited, but is, for example, 1%, 2%, 3%, 4%, or 5%.
- the rate of change of the r value is preferably 140% or less (eg, within the range of 1 to 140%), more preferably 120% or less (eg, within the range of 1 to 120%), still more preferably 100% or less (eg, : within the range of 1 to 100%).
- Piezoelectric constant d 33 ⁇ Method for Determining Piezoelectric Constant d33 >
- the piezoelectric constant d33 is measured using a piezometer system PM300 from PIEZOTEST, or equivalent, by applying a force of 1.0 N, 110 Hz.
- the piezoelectric constant d33 can be measured at 10 points on the film selected without arbitrariness, and the arithmetic mean value can be taken as the piezoelectric constant d33 .
- Selecting 10 points on the film without arbitrariness can be done, for example, by selecting 10 points at intervals of 50 mm on a straight line.
- arbitrariness means that the coefficient of variation, which will be described later, is intended to be small.
- the measured value of the piezoelectric constant d33 is a positive value or a negative value depending on the front and back of the film to be measured, but in this specification, the absolute value is described as the value of the piezoelectric constant d33 . .
- the lower limit of the piezoelectric constant d33 is preferably 13 pC/N, more preferably 14 pC/N, still more preferably 15 pC/N, still more preferably 16 pC/N.
- the lower limit of the piezoelectric constant d33 can be set to a higher value, for example 17 pC/N.
- the lower limit of the piezoelectric constant d33 after heating at 110° C. for 10 minutes is preferably 10 pC/N, more preferably 11 pC/N, still more preferably 12 pC/N, still more preferably 13 pC/N.
- the upper limit of the piezoelectric constant d33 is not particularly limited, but can be, for example, 100 pC/N, 50 pC/N, 35 pC/N, or 30 pC/N.
- the upper limit of the piezoelectric constant d33 after heating at 110° C. for 10 minutes can also be set to a similar value.
- the piezoelectric constant d33 is preferably 13 pC/N or more (eg, within the range of 13 to 100 pC/N), more preferably 14 pC/N or more (eg, within the range of 14 to 100 pC/N), still more preferably 15 pC/N. N or more (eg, within the range of 15 to 100 pC/N).
- the piezoelectric constant d33 after heating at 110° C. for 10 minutes is preferably 10 pC/N or more (eg, within the range of 10 to 100 pC/N), more preferably 11 pC/N or more (eg, 11 to 100 pC/N). within the range), more preferably 12 pC/N or more (eg, within the range of 12 to 100 pC/N). Even if the piezoelectric constant d33 is within such a range, high transparency can be exhibited.
- the “rate of change of the piezoelectric constant d 33 ” is the value obtained by the formula: ((d 33 after heating at 110° C. for 10 minutes) ⁇ (d 33 ))/(d 33 ) ⁇ 100. means absolute value.
- the upper limit of the rate of change of the piezoelectric constant d33 is preferably 50%, more preferably 45%, and even more preferably 40%.
- the upper limit of the rate of change of the piezoelectric constant d33 can be set to a lower value, such as 35%, 30%, 25%, 20%, or 15%.
- the rate of change of the piezoelectric constant d33 is not particularly limited, it is, for example, 0.5% or 1%.
- the rate of change of the piezoelectric constant d33 is preferably 50% or less (eg, within the range of 0.5 to 50%), more preferably 45% or less (eg, within the range of 0.5 to 45%), still more preferably is 40% or less (eg, within the range of 0.5 to 40%).
- the coefficient of variation of piezoelectric constant d33 is the ratio of the standard deviation of the piezoelectric constant d33 to the arithmetic mean.
- the upper limit of the coefficient of variation of the piezoelectric constant d33 is preferably 2, more preferably 1.5, still more preferably 1 from the viewpoint of in-plane uniformity.
- the lower limit of the coefficient of variation of the piezoelectric constant d33 is preferably 0.01 in terms of manufacturing cost.
- the coefficient of variation of the piezoelectric constant d33 is preferably 2 or less (eg, within the range of 0.01 to 2), more preferably 1.5 or less (eg, within the range of 0.01 to 1.5), still more preferably is 1 or less (eg, within the range of 0.01 to 1).
- Retardation is obtained by cutting a film sample into a size of 2 cm x 2 cm or more, and using a retardation film/optical material inspection device RETS-100 (product name, Otsuka Electronics) or its equivalent. Determined by measurement. In this specification, a value of 550 nm is adopted as a numerical value of retardation.
- the upper limit of the retardation is preferably 9000 nm, more preferably 8500 nm, still more preferably 8000 nm from the viewpoint of optical properties.
- the upper limit of retardation can also be set to even lower values, such as 7000 nm, 6000 nm, 5000 nm, 4000 nm, 3000 nm, 2000 nm, 1000 nm, 500 nm, 100 nm, 50 nm, or 30 nm.
- the lower limit of retardation is not particularly limited, but can be, for example, 0.1 nm, 0.5 nm, or 1 nm.
- the retardation may preferably be in the range of 0.1-100 nm, more preferably in the range of 0.5-50 nm, even more preferably in the range of 1-30 nm.
- Ratio of retardation [nm] / film thickness [ ⁇ m] The upper limit of the ratio of retardation [nm] / film thickness [ ⁇ m] is preferably 10, more preferably 5, still more preferably 1, and still more preferably Preferably it is 0.5.
- the lower limit of the ratio of retardation [nm]/film thickness [ ⁇ m] is not particularly limited, but is, for example, 0.01, 0.02, 0.03, 0.04, 0.05, or 0.1. can be done.
- the ratio of retardation [nm] / film thickness [ ⁇ m] is preferably in the range of 0.01 to 10, more preferably in the range of 0.01 to 1, still more preferably in the range of 0.01 to 0.5 is.
- Crystallinity ⁇ Method for determining crystallinity> In the X-ray diffraction pattern obtained when the film sample is directly placed on the sample holder provided with the opening and the X-ray diffraction measurement is performed over the range where the diffraction angle 2 ⁇ is 10 to 40 °, A straight line connecting the diffraction intensity at a diffraction angle 2 ⁇ of 10° and the diffraction intensity at a diffraction angle 2 ⁇ of 25° is set as a baseline, and the area surrounded by the baseline and the diffraction intensity curve is divided into 2 by profile fitting.
- the lower limit of crystallinity is preferably 40%, more preferably 45%, still more preferably 50%, still more preferably 55%, particularly preferably 60%, and particularly more preferably 65% from the viewpoint of piezoelectricity. can be.
- the lower limit of crystallinity after heating at 110° C. for 10 minutes can also be set to a similar value.
- the upper limit of crystallinity can be, for example, 99%, 95%, or 90%.
- the upper limit of crystallinity after heating at 110° C. for 10 minutes can also be set to a similar value.
- the degree of crystallinity is preferably 40% or more (eg: within the range of 40 to 99%), more preferably 50% or more (eg: within the range of 50 to 99%), more preferably 60% or more (eg: 60 ⁇ 99%).
- the range of crystallinity after heating at 110° C. for 10 minutes can also be set to the same range. Even if the degree of crystallinity is in such a range, high transparency can be exhibited.
- the YI value refers to the degree of yellowness measured according to JIS K7105.
- the YI value is determined by cutting a film sample into a size of 2 cm ⁇ 2 cm or more and measuring transmission using a spectrophotometer (CM-5, manufactured by Konica Minolta) or its equivalent. be.
- the upper limit of the YI value is preferably 4, more preferably 3, still more preferably 2.
- the upper limit of the YI value after heating at 110° C. for 10 minutes can also be set to a similar value.
- the lower limit of the YI value is not particularly limited, but can be, for example, 0.1 or 0.2.
- the YI value is preferably 4 or less (eg, within the range of 0.1 to 4), more preferably 3 or less (eg, within the range of 0.1 to 3), still more preferably 2 or less (eg, 0.1 ⁇ 2).
- the range of YI values after heating at 110° C. for 10 minutes can also be set in the same range.
- the "YI value change rate” is the absolute value of the value obtained by the formula: ((YI value after heating at 110 ° C. for 10 minutes) - (YI value)) / (YI value) ⁇ 100 means
- the upper limit of the YI value change rate is preferably 150%, more preferably 100%, even more preferably 90%, even more preferably 80%, and particularly preferably 70%, from the viewpoint of thermal stability.
- the lower limit of the YI value change rate is not particularly limited, it is, for example, 1% or 5%.
- YI value change rate is preferably 150% or less (eg, within the range of 1 to 150%), more preferably 100% or less (eg, within the range of 1 to 100%), more preferably 80% or less (eg : within the range of 1 to 80%).
- Remanent polarization amount [mC/m 2 ] ⁇ Method for Determining Residual Polarization Amount>
- the sample film was cut out to 20 mm ⁇ 20 mm, and an aluminum electrode (flat electrode) was patterned by vacuum processing vapor deposition on the central portion of 5 mm ⁇ 5 mm of the film. It is obtained by adhering electrodes of two leads (3 mm ⁇ 80 mm) with a conductive double-sided tape.
- This sample film, function generator, high-voltage amplifier, and oscilloscope are incorporated into a Sawyer tower circuit, a triangular wave is applied to the sample film (maximum ⁇ 10 kV), and the response of the sample film is measured using an oscilloscope. /m is obtained.
- the lower limit of the residual polarization amount is preferably 30 mC/m 2 , 35 mC/m 2 , 40 mC/m 2 , 45 mC/m 2 or 50 mC/m 2 .
- the upper limit of the residual polarization amount is not particularly limited, but is, for example, 200 mC/m 2 , 150 mC/m 2 , 100 mC/m 2 , 90 mC/m 2 , 80 mC/m 2 or 70 mC/m 2 .
- the residual polarization amount is preferably 30 mC/m 2 or more (eg, within the range of 30 to 200 mC/m 2 or 30 to 100 mC/m 2 ), more preferably 40 mC/m 2 or more (eg, 40 to 90 mC/m 2 ), more preferably 50 mC/m 2 or more (eg, within a range of 50 to 80 mC/m 2 ).
- the crystal size is not particularly limited.
- the organic piezoelectric film preferably contains acicular or fibrous crystals and preferably has the following average crystal length, average crystal width, and/or maximum crystal length.
- ⁇ Method for Determining Average Crystal Length, Average Crystal Width, and Maximum Crystal Length> A scanning electron microscope (SEM) image of the film sample surface is observed. Observation with an electron microscope image is performed at a magnification selected from the range of 10,000 to 100,000 times according to the size of the needle-like crystals. However, the sample, observation conditions, and magnification are adjusted so as to satisfy the following conditions (1) and (2).
- a single straight line X is drawn at an arbitrary point in the observed image, and 20 or more needle-like crystals intersect this straight line X.
- the upper limit of the average crystal length is preferably 450 nm, more preferably 400 nm, still more preferably 350 nm, even more preferably 300 nm, particularly preferably 250 nm, and particularly preferably 200 nm.
- the lower limit of the average crystal length is not particularly limited, but is, for example, 1 nm, 5 nm, 10 nm, 120 nm, 30 nm, 40 nm, or 50 nm.
- the average crystal length is preferably 450 nm or less (eg, within the range of 1 to 450 nm), more preferably 300 nm or less (eg, within the range of 1 to 300 nm), and still more preferably 200 nm or less (eg, within the range of 1 to 200 nm). ).
- the upper limit of the maximum crystal length is preferably 800 nm, more preferably 700 nm, even more preferably 600 nm, still more preferably 500 nm, and particularly preferably 400 nm. From the viewpoint of transparency, the upper limit of the maximum crystal length is preferably the minimum wavelength of visible light (380 nm), more preferably 350 nm, and even more preferably 300 nm. Although the lower limit of the maximum crystal length is not particularly limited, it is, for example, 10 nm.
- the maximum crystal length is preferably 800 nm or less (eg, within the range of 10 to 800 nm), more preferably 600 nm or less (eg, within the range of 10 to 600 nm), still more preferably 380 nm or less (eg, within the range of 10 to 380 nm). ).
- the upper limit of the average crystal width is preferably 100 nm, more preferably 80 nm, even more preferably 60 nm, still more preferably 50 nm.
- the upper limit of the average crystal width can be set to even lower values, for example 40 nm, 35 nm, or 30 nm.
- the lower limit of the average crystal width is not particularly limited, it is, for example, 1 nm.
- the average crystal width is preferably 100 nm or less (eg, within the range of 1 to 100 nm), more preferably 80 nm or less (eg, within the range of 1 to 80 nm), and still more preferably 60 nm or less (eg, within the range of 1 to 60 nm). ).
- Film thickness ⁇ Method for determining film thickness> the thickness is measured using a photoelectric digital length measurement system (Digimicro MH-15M, manufactured by Nikon) or its equivalent at 10 points in every 1 cm square over the entire planar direction of the film. and the average value is taken as the film thickness.
- a photoelectric digital length measurement system Digimicro MH-15M, manufactured by Nikon
- the lower limit of the film thickness is preferably 1 ⁇ m, more preferably 5 ⁇ m, even more preferably 10 ⁇ m, even more preferably 15 ⁇ m, and particularly preferably 20 ⁇ m, from the viewpoint of being usable as a self-supporting film.
- the lower limit of the film thickness is not particularly limited when formed on a support such as glass or PET film, but is preferably 10 nm, more preferably 30 nm, and still more preferably 50 nm from the viewpoint of obtaining a smooth surface without defects.
- the upper limit of the film thickness is not particularly limited, but from the viewpoint of obtaining flexibility, it can be, for example, 1000 ⁇ m, 900 ⁇ m, or 800 ⁇ m.
- the film thickness is preferably 1 ⁇ m or more (eg, within the range of 1 to 1000 ⁇ m), more preferably 5 ⁇ m or more (eg, within the range of 5 to 1000 ⁇ m), still more preferably 10 ⁇ m or more (eg : within the range of 10 to 1000 ⁇ m).
- it is preferably 10 nm or more (eg, within the range of 10 nm to 1000 ⁇ m), more preferably 30 nm or more (eg, within the range of 30 nm to 1000 ⁇ m), still more preferably 50 nm or more. (eg, within the range of 50 nm to 1000 ⁇ m).
- the upper limit of the variation coefficient of film thickness is preferably 10%, more preferably 5%, from the viewpoint of in-plane uniformity.
- the lower limit of the coefficient of variation of film thickness is not particularly limited, but can be, for example, 0.01%, 0.05%, or 0.1%.
- the variation coefficient of film thickness is preferably 10% or less (eg, within the range of 0.01 to 10%), more preferably 5% (eg, within the range of 0.01 to 5%).
- the lower limit of the area area is not particularly limited, it is preferably 9 cm 2 , more preferably 10 cm 2 from the viewpoint of industrial productivity.
- the lower area limit can be set to even higher values, for example 50 cm 2 , 100 cm 2 , 200 cm 2 , 300 cm 2 , 400 cm 2 or 500 cm 2 . This is not the case when printing or applying to a fine area, and the lower limit of the area can be, for example, 0.1 ⁇ m 2 , 1 ⁇ m 2 , 10 ⁇ m 2 , 50 ⁇ m 2 or 100 ⁇ m 2 .
- the upper limit of the area is not particularly limited, but can be, for example, 4000 m 2 , 3000 m 2 , 2000 m 2 , 1000 m 2 or 500 m 2 .
- the upper limit of the area can be, for example, 10 mm 2 , 5 mm 2 or 1 mm 2 .
- the area is preferably 9 cm 2 or more (eg within the range of 9 cm 2 to 4000 m 2 ), more preferably 10 cm 2 or more (eg within the range of 10 cm 2 to 4000 m 2 ).
- the range corresponds to the range of areas produced in a roll-to-roll process.
- the organic piezoelectric film preferably satisfies any one of the following (a) to (w). (a) a total light transmittance of 90% or more, an internal haze value per unit film thickness of 0.2%/ ⁇ m or less, and a piezoelectric constant d33 of 10 pC/N or more after heating at 110° C.
- the total light transmittance is 90% or more, the internal haze value per unit film thickness is 0.2%/ ⁇ m or less, the piezoelectric constant d33 after heating at 110° C. for 10 minutes is 10 pC/N or more, and the unit film Retardation per thickness is in the range of 0.01 to 10 nm/ ⁇ m, and film thickness is in the range of 1 to 1000 ⁇ m;
- a total light transmittance of 90% or more, an internal haze value (or an internal haze value after heating at 110°C for 10 minutes) of 6% or less, and a piezoelectric constant of d 33 after heating at 110°C for 10 minutes. is 10 pC/N or more and YI value is 4 or less;
- the average crystal length is 200 nm or less, the maximum crystal length is 800 nm or less, the average crystal width is 100 nm or less, the piezoelectric constant d33 after heating at 110°C for 10 minutes is 10 pC/N or more, and the degree of crystallinity is 40%.
- the organic piezoelectric film of the present disclosure can be applied to various applications.
- Specific examples of applications include sensors (e.g., touch sensors, vibration sensors, biosensors, tire sensors (sensors installed on the inner surface of tires)), actuators, touch panels, haptic devices (devices that have the function of providing tactile feedback to the user), Includes vibration power generators (eg, vibration power floors, vibration power tires), speakers, and microphones.
- the organic piezoelectric film of the present disclosure is manufactured by, for example, Step A of preparing a non-polarized film (e.g., non-stretched and non-polarized film) containing a piezoelectric polymer by a casting method; Step B of polarizing a non-polarized film (e.g., unstretched and non-polarized film); Heat treatment process C A manufacturing method comprising at least one step of, preferably, It can be manufactured by a manufacturing method including steps A to C.
- Step A non-polarized film e.g., non-stretched and non-polarized film
- Step B of polarizing a non-polarized film (e.g., unstretched and non-polarized film)
- Heat treatment process C A manufacturing method comprising at least one step of, preferably, It can be manufactured by a manufacturing method including steps A to C.
- a method for producing a non-polarized film by a casting method is, for example, (A1) The liquid composition is dissolved by dissolving or dispersing the piezoelectric polymer (e.g., vinylidene fluoride-based polymer) and the above-described optional components (e.g., inorganic oxide particles and affinity improver) in a solvent. to prepare a liquid composition; (A2) applying (casting or coating) the liquid composition onto a substrate; (A3) drying the substrate to which the liquid composition has been applied by heating at a first temperature; and (A4) heating the substrate heated at the first temperature to a second temperature higher than the first temperature. It is a manufacturing method including a step of heating at a temperature.
- the piezoelectric polymer e.g., vinylidene fluoride-based polymer
- optional components e.g., inorganic oxide particles and affinity improver
- Steps (A3) and (A4) may be performed by sequentially transferring to a zone exposed to a first temperature and a zone exposed to a second temperature higher than the first temperature.
- the dissolution temperature in the preparation of the liquid composition can be appropriately selected depending on the type of solvent used, and is not particularly limited, but from the viewpoint of dissolution promotion and film coloration prevention, it is preferably room temperature or higher. , the vaporization temperature of the solvent or 80° C. or less.
- the solvent include ketone solvents (eg methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), acetone, diethyl ketone, dipropyl ketone, cyclohexanone), ester solvents (eg : ethyl acetate, methyl acetate, propyl acetate, butyl acetate, ethyl lactate), ether solvents (e.g. tetrahydrofuran, methyltetrahydrofuran, dioxane), and amide solvents (e.g. dimethylformamide (DMF), dimethylacetamide). .
- ketone solvents eg methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), acetone, diethyl ketone, dipropyl ketone, cyclohexanone
- ester solvents eg : eth
- the liquid composition is cast (or applied) onto the substrate by a conventional method (e.g., knife coating method, cast coating method, roll coating method, gravure coating method, blade coating method, rod coating method, air doctor coating method, or slot die method).
- a conventional method e.g., knife coating method, cast coating method, roll coating method, gravure coating method, blade coating method, rod coating method, air doctor coating method, or slot die method.
- the gravure coating method or the slot die method is preferable from the viewpoints of easy operability, little variation in the thickness of the obtained film, and excellent productivity.
- the base material examples include plastic films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), acrylic resins, cycloolefin polymers, and polyimide (PI), or aluminum (Al), Metal films such as stainless steel (SUS) and copper (Cu) can be used.
- PET polyethylene terephthalate
- PEN polyethylene naphthalate
- PC polycarbonate
- acrylic resins cycloolefin polymers
- PI polyimide
- Al aluminum
- Metal films such as stainless steel (SUS) and copper (Cu) can be used.
- PET polyethylene terephthalate
- PET polyethylene terephthalate
- PEN polyethylene naphthalate
- PC polycarbonate
- PI polyimide
- Al aluminum
- Metal films such as stainless steel (SUS) and copper (Cu) can be used.
- SUS stainless steel
- Cu copper
- PET polyethylene terephthalate
- PET polyethylene terephthalate
- the heat drying of the substrate to which the liquid composition is applied may be performed according to the heat drying method for ordinary film formation.
- the heat-drying may preferably be carried out by passing the liquid composition applied onto the substrate through a high-temperature oven (or a drying oven), for example, by a roll-to-roll method.
- the film may be formed by heating and drying batchwise.
- the lower limit of the first temperature can be appropriately selected depending on the type of solvent used (or vaporization temperature), for example 20 ° C., preferably 30 ° C., more preferably 40 ° C., still more preferably 50 ° C. , still more preferably 60°C, particularly preferably 70°C, particularly more preferably 80°C.
- the upper limit of the heat drying temperature is, for example, 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, 140°C, 130°C, or 120°C.
- the heat drying temperature is, for example, within the range of 50 to 140.degree. C., 60 to 130.degree. C., 70 to 120.degree. C., or 80 to 130.degree.
- the heat-drying temperature may be a constant temperature or may be changed.
- the heat drying temperature may be changed, for example, from a low temperature (eg, 40-100° C.) to a high temperature (eg, 120-200° C.).
- the method for changing the heat drying temperature is not particularly limited, but for example, the heat drying temperature may be changed by moving a plurality of drying zones set to different temperatures.
- the lower limit of the time for heating at the first temperature is, for example, 1 second, preferably 10 seconds, and more preferably 30 seconds.
- the upper limit of the heat drying time is, for example, 60 minutes, preferably 30 minutes, more preferably 10 minutes.
- the heat drying time is, for example, within the range of 10 seconds to 60 minutes, preferably within the range of 30 seconds to 10 minutes, more preferably within the range of 30 seconds to 10 minutes.
- the second temperature is preferably at or near the melting point.
- the temperature at or near the melting point may be (melting point ⁇ 12° C.) or higher and (melting point +12° C.) or lower.
- the second temperature is more preferably (melting point -11°C) or higher, (melting point -10°C) or higher, (melting point -9°C) or higher, (melting point -8°C) or higher, (melting point -7°C) or higher, ( (melting point ⁇ 6° C.) or higher, or (melting point ⁇ 5° C.) or higher.
- the second temperature is more preferably (melting point +11°C) or lower, (melting point +10°C) or lower, (melting point +9°C) or lower, (melting point +8°C) or lower, (melting point +7°C) or lower, (melting point +6°C) ) or less, or (melting point +5°C) or less.
- the second temperature is preferably within the range of (melting point ⁇ 12° C.) to (melting point +12° C.), more preferably within the range of (melting point ⁇ 10° C.) to (melting point +10° C.), still more preferably (melting point ⁇ 10° C.) ° C.) to (melting point +5° C.) or (melting point -5° C.) to (melting point +5° C.).
- the second temperature varies depending on the type of piezoelectric polymer, but is preferably 110° C. or higher, more preferably 115° C. or higher, still more preferably 120° C. or higher, and still more preferably 125° C. or higher. Also, the second temperature is preferably 150° C.
- the second temperature is preferably within the range of 110-150°C, more preferably within the range of 120-140°C, and even more preferably within the range of 125-135°C.
- the heating time at the second temperature is, for example, 1 minute or longer, preferably 5 minutes or longer, and more preferably 10 minutes or longer.
- the time for heating at the second temperature is, for example, 60 minutes or less, preferably 30 minutes or less.
- the time for heating at the second temperature is, for example, within the range of 1 to 60 minutes, preferably within the range of 5 to 60 minutes, more preferably within the range of 10 to 60 minutes.
- the method for producing a non-polarized film may further include (A5) the step of heating the substrate heated at the second temperature to a third temperature.
- the third temperature is preferably at or near the crystallization temperature.
- the crystallization temperature or a temperature in the vicinity thereof can be (crystallization temperature - 12°C) or higher and (crystallization temperature + 12°C) or lower.
- the third temperature is more preferably (crystallization temperature -11°C) or higher, (crystallization temperature -10°C) or higher, (crystallization temperature -9°C) or higher, (crystallization temperature -8°C) or higher, ( (crystallization temperature -7°C) or higher, (crystallization temperature -6°C) or higher, (crystallization temperature -5°C) or higher, (crystallization temperature -4°C) or higher, or (crystallization temperature -3°C) or higher be.
- the third temperature is more preferably (crystallization temperature + 11 ° C.) or less, (crystallization temperature + 10 ° C.) or less, (crystallization temperature + 9 ° C.) or less, (crystallization temperature + 8 ° C.) or less, (crystallization temperature + 7°C) or less, (crystallization temperature + 6°C) or less, (crystallization temperature + 5°C) or less, (crystallization temperature + 4°C) or less, or (crystallization temperature + 3°C) or less.
- the third temperature is preferably within the range of (crystallization temperature ⁇ 10° C.) to (crystallization temperature +10° C.), more preferably within the range of (crystallization temperature ⁇ 5° C.) to (crystallization temperature +5° C.). and more preferably within the range of (crystallization temperature -3°C) to (crystallization temperature +3°C).
- the third temperature varies depending on the type of piezoelectric polymer, but is preferably 108° C. or higher, more preferably 110° C. or higher, still more preferably 113° C. or higher, and particularly preferably 115° C. or higher. Also, the third temperature is preferably 128° C. or lower, more preferably 125° C.
- the third temperature is preferably within the range of 108-128°C, more preferably within the range of 113-123°C, and even more preferably within the range of 115-121°C.
- the time for heating at the third temperature is, for example, 1 minute or longer, preferably 3 minutes or longer, and more preferably 5 minutes or longer. Also, the time for heating at the third temperature is, for example, 10 minutes or less.
- the time for heating at the third temperature is, for example, within the range of 1 to 10 minutes, preferably within the range of 3 to 10 minutes.
- Heating at the third temperature is preferable in terms of promoting crystal growth, suppressing changes in properties due to heating, and obtaining a film with a high piezoelectric constant.
- heating at the third temperature may be omitted from the viewpoint of industrial productivity depending on the film to be obtained.
- the thickness of the non-polarized film prepared in step A may be set according to the film to be obtained.
- Polarization treatment can be carried out by a conventional method, preferably by corona discharge treatment.
- the conditions for corona discharge treatment may be appropriately set based on common knowledge in the relevant technical field. Either a negative corona or a positive corona may be used for corona discharge, but it is desirable to use a negative corona from the viewpoint of the ease of polarizing a non-polarized film.
- Corona discharge treatment is not particularly limited. It can be done by performing the application with a needle-like electrode on the non-polarized film; or by performing the application with a grid electrode on the non-polarized film.
- the distance between each acicular electrode and/or linear electrode and the film should be constant. It is desirable that there is no (or extremely small) variation in the distance between the film planes (specifically, the difference between the longest distance and the shortest distance is preferably within 15 mm, more preferably within 10 mm).
- the DC electric field is, for example, ⁇ 10 ⁇ -25 kV.
- the processing speed is, for example, within the range of 10-1200 cm/min.
- the polarization treatment may be performed by, for example, sandwiching a non-polarized film between flat electrodes from both sides and applying voltage, instead of corona discharge.
- a DC electric field within the range of 0 to 400 MV / m (preferably 50 to 400 MV / m) and 0.1 second Application time conditions within the range of ⁇ 60 minutes can be employed.
- Step C is preferably performed at any time relative to Step B and as needed. That is, step C may be performed before step B, at the same time as step B, or after step B. If step C is performed after step B, the heat treatment of step C can be performed on the polarized film obtained in step B or on the portion that has undergone polarization in step B. That is, while the polarization treatment of step B is being performed, the heat treatment of step C may be performed on the portion for which the polarization treatment has been completed.
- the heat treatment is not particularly limited, but for example, sandwiching the film between two metal plates and heating the metal plates; heating the roll of the film in a constant temperature bath; or by a roll-to-roll method heating a metal roll and contacting the film with the heated metal roll; or passing the film roll-to-roll through a heated oven.
- the polarized film may be heat-treated alone, or may be laminated on another type of film or metal foil to prepare a laminated film, which may be heat-treated. .
- the latter method is preferable when heat-treating at a high temperature because the polarized film is less likely to wrinkle.
- the heat treatment temperature may vary depending on the type of polarized film to be heat-treated, and is preferably within the range of (melting point of the polarized film to be heat-treated ⁇ 100) ° C. to (melting point of the polarized film to be heat-treated +40) ° C. is.
- the heat treatment temperature is preferably 80° C. or higher, more preferably 85° C. or higher, and still more preferably 90° C. or higher.
- the temperature of the heat treatment is preferably 170° C. or lower, more preferably 160° C. or lower, and even more preferably 140° C. or lower.
- the heat treatment time is usually 10 seconds or longer, preferably 0.5 minutes or longer, more preferably 1 minute or longer, and still more preferably 2 minutes or longer. Although the upper limit of the heat treatment time is not limited, the heat treatment time is usually 60 minutes or less.
- the heat treatment conditions are preferably 90°C or higher for 1 minute or longer.
- Organic piezoelectric films can preferably be stored and shipped as rolls.
- the roll of one embodiment of the present disclosure may consist of the film only, or may be in a form in which the film is laminated with a protective film or the like and wound, a core such as a paper tube, and the film wound around the core may be provided.
- the film roll preferably has a width of 50 mm or more and a length of 20 m or more.
- a roll of the film can be prepared, for example, by winding the film using an unwinding roller and a winding roller.
- roller in order to improve the slipperiness of the film, it is preferable to use a roller with good slipperiness, specifically a roller coated with fluororesin, a plated roller, or a roller coated with a release agent.
- both ends are recessed compared to the center; roll thickness non-uniformity, which can cause wrinkles. This can also cause the film to sag (curve in the absence of tension other than gravity tension) during unwinding of the film.
- the edge of the film which is the edge of the roll, is slit by a slitter. It is difficult to prevent ridges and dents in the roll only with a chisel.
- the width of the film can be widened (e.g., 100 mm or more in width) as it is or by simply slitting the film end, which will be the end of the roll, with a slitter. And, even when the length of the film is long (for example, 50 m or longer), the roll can be made with the protrusions, the dents, and the deflection suppressed.
- the selvage (film edge) removed by the slit can be collected and recycled as a raw material for the film.
- the roll of the film has a highly uniform thickness, and preferably the ratio of the thickness of the thicker end to the thickness of the center in the axial direction of the roll is in the range of 70 to 130%. . As a result, the film unwound from the film roll is restrained from bending.
- At least the surface material of the roller used for manufacturing the film and its roll is polytetrafluoroethylene (PTFE), chromium plating, or stainless steel (SUS).
- PTFE polytetrafluoroethylene
- SUS stainless steel
- the wrinkles of the film can be suppressed.
- the piezoelectric body of one embodiment of the present disclosure may be a laminate, and may include an organic piezoelectric film and an electrode provided on at least one surface of the organic piezoelectric film.
- the electrodes include ITO (indium tin oxide) electrodes, tin oxide electrodes, aluminum electrodes, metal nanowires, metal nanoparticles (eg silver nanoparticles), and organic conductive resins.
- the piezoelectric body includes an organic piezoelectric film, a positive electrode layer (or upper electrode layer) provided on one side of the organic piezoelectric film, and a negative electrode layer (or lower electrode) provided on the other side of the organic piezoelectric film. layer).
- the piezoelectric body may have an insulating layer on the surface of the electrode layer on which the organic piezoelectric film is not laminated. Moreover, the piezoelectric body may have a cover (eg, an electromagnetic shield layer) on the surface (or outermost surface) of the electrode layer on which the organic piezoelectric film is not laminated.
- a cover eg, an electromagnetic shield layer
- the method of manufacturing a piezoelectric body is providing the organic piezoelectric film; and providing an electrode on at least one surface of the organic piezoelectric film.
- the method of forming the electrodes usually includes heat treatment, and specific examples thereof include physical vapor deposition (e.g., vacuum deposition, ion plating, sputtering) or It includes a method of forming a film by chemical vapor deposition (eg, plasma CVD) and a method of applying an electrode material to a substrate.
- physical vapor deposition e.g., vacuum deposition, ion plating, sputtering
- the lower limit of the heat treatment temperature is, for example, 25°C, preferably 40°C, more preferably 50°C.
- the upper limit of the temperature of the heat treatment is (melting point of the polarized film to be heat treated - 3°C), for example, 220°C, preferably 180°C, more preferably 150°C, and still more preferably 130°C.
- the temperature of the heat treatment can be, for example, within the range of 25-220°C, preferably within the range of 40-130°C.
- the heat treatment time is usually 10 seconds or longer, preferably 1 minute or longer, more preferably 10 minutes or longer, and still more preferably 15 minutes or longer.
- the weight average molecular weight (Mw) of the vinylidene fluoride (VDF)/tetrafluoroethylene (TFE) copolymer was calculated based on standard polystyrene by gel permeation chromatography (GPC) under the following conditions. . (conditions) GPC equipment: TOSOH AS-8010, CO-8020 and SIMADZURID-10A Column: 3 GMHHR-H Developing solvent: dimethylformamide [DMF] Sample concentration: 0.05% by mass
- the melting point of the vinylidene fluoride (VDF) / tetrafluoroethylene (TFE) copolymer was 10 by differential scanning calorimetry (DSC) in accordance with the plastic transition temperature measurement method (JIS K7121). It was measured as the maximum value in the heat of fusion curve obtained when the temperature was raised at a rate of °C/min.
- the total light transmittance, internal haze value, piezoelectric constant d33 , retardation, and film thickness were measured by the following methods.
- ⁇ piezoelectric constant d33 > The piezoelectric constant d33 was measured using a piezometer system PM300 from PIEZOTEST.
- a straight line connecting the diffraction intensity at a diffraction angle 2 ⁇ of 10° and the diffraction intensity at a diffraction angle 2 ⁇ of 25° was set as a baseline, and the baseline and the diffraction intensity curve
- the enclosed region was separated into two symmetrical peaks by profile fitting, of which the peak with the larger diffraction angle 2 ⁇ was identified as the crystalline peak, and the peak with the smaller diffraction angle 2 ⁇ was identified as the amorphous halo peak. .
- the degree of crystallinity was calculated by 100 ⁇ (area of crystalline peak)/(sum of area of crystalline peak and area of amorphous halo peak).
- ⁇ Residual polarization amount> An aluminum electrode (flat electrode) was patterned by vacuum processing vapor deposition on the center portion of 5 mm x 5 mm of the sample film cut out to 20 mm x 20 mm.
- This sample film, function generator, high-voltage amplifier, and oscilloscope were incorporated into a Sawyer tower circuit, and a triangular wave was applied to the sample film (maximum ⁇ 10 kV).
- the residual polarization amount at an applied electric field of 80 MV/m was obtained.
- the retardation was determined by cutting out a film sample into a size of 2 cm ⁇ 2 cm or more and measuring it using a retardation film/optical material inspection device RETS-100 (product name, Otsuka Electronics). A value of 550 nm was adopted as the numerical value of the retardation.
- a scanning electron microscope (SEM) image of the film sample surface was observed. Observation with an electron microscope image was performed at a magnification selected from a range of 1,000 to 100,000 times according to the size of the constituting needle-like crystals. However, the sample, observation conditions, and magnification were adjusted so as to satisfy the following conditions (1) and (2).
- a single straight line X is drawn at an arbitrary point in the observed image, and 20 or more needle-like crystals intersect this straight line X.
- (2) Draw a straight line Y that intersects the straight line X perpendicularly in the same observation image, and 20 or more needle-like crystals intersect the straight line Y.
- the needle-like crystals intersecting the straight line X and the needle-like crystals intersecting the straight line Y at least 20 (that is, at least 40 in total) crystal lengths (needle-like crystals ) was read. At least three sets of such electron microscope images were observed, and at least 40 x 3 sets (that is, at least 120 lines) of crystal lengths were read. The crystal lengths thus read were averaged to determine the average crystal length, and the longest crystal length was taken as the maximum crystal length. ⁇ Average crystal width> The average crystal width was obtained by analyzing the electron microscope observation image used when measuring the average crystal length.
- VDF vinylidene fluoride
- TFE tetrafluoroethylene copolymer
- the copolymer film was subjected to the following polarization treatment.
- a polarization processing ISO class 7 clean room humidity 20 to 30%
- a ground electrode made of SUS which is a grounded stage 1 (length 320 mm, width 220 mm)
- the temperature was maintained at 25° C.
- a non-polarized copolymer film 2 cut into a size of 50 mm ⁇ 50 mm was placed on the ground electrode.
- a PET film 3 of 340 ⁇ 240 mm was placed thereon so that its central portion covered the central portion of the non-polarized copolymer film 2 .
- the non-polarized copolymer film 2 placed on the stage 1 was passed through the needle-like electrode E1 and the wire electrode E2 at a moving speed of the stage 1 of 3000 mm/min to perform the polarization treatment.
- the obtained polarized copolymer film was left still in a drying oven maintained at 80° C. and subjected to heat treatment to obtain an organic piezoelectric film. Scanning electron microscope images of Example 1 and Comparative Example 3 are shown in FIG.
- Example 7-9 An organic piezoelectric film was obtained by the same procedure as in Example 1, except that after heating at the second temperature, it was further heated at the third temperature shown in Table 1 for 10 minutes.
- VDF vinylidene fluoride
- TFE tetrafluoroethylene copolymer
- Mw weight average molecular weight
- MEK methyl ethyl ketone
- VDF Vinylidene fluoride
- TFE tetrafluoroethylene copolymer
- Mw weight average molecular weight
- Mw melting point
- MEK methyl ethyl ketone
- VDF Vinylidene fluoride
- TFE tetrafluoroethylene copolymer
- Mw weight average molecular weight
- Mw melting point
- MEK methyl ethyl ketone
- the drying was performed in a drying furnace in which the drying temperatures of four zones (2 m per zone) were set to 80°C/100°C/129°C/129°C, respectively.
- the film thickness shown in Table 1 was obtained.
- Polarization treatment was carried out on the copolymer film by applying a continuous roll-to-roll voltage application using a linear electrode. After that, the same procedure as in Example 1 was followed to obtain an organic piezoelectric film.
- VDF Vinylidene fluoride
- TFE tetrafluoroethylene copolymer
- Mw weight average molecular weight
- MEK methyl ethyl ketone
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Abstract
Description
項1.
全光線透過率が90%以上であり、
単位膜厚あたりの内部ヘイズ値が0.2%/μm以下であり、
110℃で10分加熱した後の圧電定数d33が10pC/N以上である、
有機圧電フィルム。
項2.
フッ化ビニリデン系共重合体フィルムからなる、項1に記載の有機圧電フィルム。
項3.
前記フッ化ビニリデン系共重合体が、フッ化ビニリデン/テトラフルオロエチレン共重合体、及びフッ化ビニリデン/トリフルオロエチレン共重合体からなる群より選択される少なくとも一種である、項2に記載の有機圧電フィルム。
項4.
前記フッ化ビニリデン系共重合体において、フッ化ビニリデンの組成比率が60~85モル%の範囲内である、項2又は3に記載の有機圧電フィルム。
項5.
膜厚が10nm~1000μmである、項1~4のいずれか一項に記載の有機圧電フィルム。
項6.
リタデーションが500nm以下である、項1~5のいずれか一項に記載の有機圧電フィルム。
項7.
YI値が4以下である、項1~6のいずれか一項に記載の有機圧電フィルム。
項8.
残留分極量が40mC/m2以上である、項1~7のいずれか一項に記載の有機圧電フィルム。
項9.
開口部が設けられたサンプルホルダにフィルム試料を直接載置し、回折角2θが10~40°である範囲にわたってX線回折測定を行ったときに得られるX線回折パターンにおいて、
10°の回折角2θにおける回折強度と、25°の回折角2θにおける回折強度とを結ぶ直線をベースラインとして設定し、及び
当該ベースラインと回折強度曲線とで囲まれる領域を、プロファイルフィッティングにより2つの対称性ピークに分離し、
このうち、回折角2θの大きい方を結晶性ピークと認定し、且つ回折角2θの小さい方を非晶性ハローピークと認定した場合に、
100×(結晶性ピークの面積)/(結晶性ピークの面積と非晶性ハローピークの面積との和)で表される結晶化度が40%以上である、項1~8のいずれか一項に記載の有機圧電フィルム。
項10.
針状の結晶を含有するフッ化ビニリデン系共重合体フィルムからなり、
最大結晶長が800nm以下であり、
110℃で10分加熱した後の圧電定数d33が10pC/N以上である、
有機圧電フィルム。
項11.
平均結晶長が450nm以下である、項10に記載の有機圧電フィルム。
項12.
開口部が設けられたサンプルホルダにフィルム試料を直接載置し、回折角2θが10~40°である範囲にわたってX線回折測定を行ったときに得られるX線回折パターンにおいて、
10°の回折角2θにおける回折強度と、25°の回折角2θにおける回折強度とを結ぶ直線をベースラインとして設定し、及び
当該ベースラインと回折強度曲線とで囲まれる領域を、プロファイルフィッティングにより2つの対称性ピークに分離し、
このうち、回折角2θの大きい方を結晶性ピークと認定し、且つ回折角2θの小さい方を非晶性ハローピークと認定した場合に、
100×(結晶性ピークの面積)/(結晶性ピークの面積と非晶性ハローピークの面積との和)で表される結晶化度が40%以上である、項10又は11に記載の有機圧電フィルム。
項13.
センサ、アクチュエータ、タッチパネル、ハプティックデバイス、振動発電装置、スピーカー、及びマイクからなる群より選択される1種以上に使用するための、項1~12のいずれか一項に記載の有機圧電フィルム。
項14.
積層体であり、
項1~12のいずれか一項に記載の有機圧電フィルム、及び
前記有機圧電フィルムの少なくとも一方の面上に設けられた電極を備える圧電体。
項15.
キャスティング法により無延伸かつ非分極のフッ化ビニリデン系重合体フィルムを調製する工程A;
前記無延伸かつ非分極のフッ化ビニリデン系重合体フィルムを分極処理する工程B;及び工程Bに対して任意の時点で、無延伸のフッ化ビニリデン系重合体フィルムを熱処理する工程C
を含む有機圧電フィルムの製造方法であって、
工程Aが、フッ化ビニリデン系重合体の融点をT℃としたとき、(T-10)℃~(T+5)℃の範囲内で加熱する工程A3を含む、有機圧電フィルムの製造方法。
本明細書中の記号及び略号は、特に言及のない限り、本明細書の文脈に沿い、本開示が属する技術分野において通常用いられる意味に理解できる。
本開示の有機圧電フィルムは、有機物である圧電性ポリマーを含有する。圧電性ポリマーとしては、例えば、フッ化ビニリデン系重合体、シアン化ビニリデン系重合体、奇数鎖ナイロン、ポリ乳酸等が挙げられるが、これらに限定されない。圧電性ポリマーは、1種単独であっても2種以上の組合せであってもよい。圧電性ポリマーとしては、フッ化ビニリデン系重合体が好ましい。フッ化ビニリデン系重合体は、好ましくは分極化フッ化ビニリデン系重合体である。本明細書において、用語「分極化」とは、表面に電荷が付与されていることを意味する。すなわち、分極化フッ化ビニリデン系重合体は、エレクトレット又は圧電体、或いは強誘電体であることができる。
特に、重量平均分子量が10万以上200万以下であることが好ましい。また、重量平均分子量の下限は、20万以上であることがより好ましく、30万以上であることが更に好ましく、60万以上であることが最も好ましい。重量平均分子量の上限は、190万以下であることがより好ましく、180万以下であることが更に好ましく、110万以下であることが最も好ましい。
なお、重量平均分子量(Mw)は、例えば、ゲル浸透クロマトグラフ(GPC)によって測定することができる。
具体的には、GPC法により下記条件にて測定した結果に基づき、標準ポリスチレンを基準として分子量を算出できる。
(条件)
GPC装置:TOSOH AS-8010、CO-8020及び
SIMADZURID-10A
カラム:GMHHR-H 3本
展開溶媒:ジメチルホルムアミド〔DMF〕
試料濃度:0.05質量%
(B1)は、周期表の2族、3族、4族、12族又は13族の金属元素の酸化物の粒子、又はこれらの無機酸化物複合粒子である。前記金属元素の例は、Be、Mg、Ca、Sr、Ba、Y、Ti、Zr、Zn、及びAlを包含する。
(B1)の好適な例は、Be、Al、Mg、Y、及びZrの酸化物の粒子を包含する。前記粒子は、汎用で安価であり、また体積抵抗率が高い点から好ましい。
(B1)の更に好適な例は、Al2O3、MgO、ZrO2、Y2O3、BeO、及びMgO・Al2O3からなる群より選ばれる少なくとも1種の無機酸化物の粒子を包含する。前記粒子は、体積抵抗率が高い点から好ましい。
(B1)の更に好適な例は、結晶構造がγ型のAl2O3を包含する。前記粒子は、比表面積が大きく、圧電性ポリマーへの分散性が良好な点から好ましい。
(B2)は、式:
M1 a1M2 b1Oc1
(式中、M1は2族金属元素;M2は4族金属元素であり;a1は0.9~1.1の範囲内であり;b1は0.9~1.1の範囲内であり;c1は2.8~3.2の範囲内である;M1及びM2はそれぞれ1種又は2種以上の金属元素であることができる)
で表される無機複合酸化物の粒子である。
前記2族金属元素の好適な例は、Mg、Ca、Sr、及びBaを包含する。
前記4族金属元素の好適な例は、Ti、及びZrを包含する。
(B2)の好適な例は、BaTiO3、SrTiO3、CaTiO3、MgTiO3、BaZrO3、SrZrO3、CaZrO3、及びMgZrO3からなる群より選ばれる少なくとも1種の無機酸化物の粒子を包含する。前記粒子は、体積抵抗率が高い点から好ましい。
(B3)は、周期表の2族、3族、4族、12族、又は13族の金属元素の酸化物、及び酸化ケイ素の無機酸化物複合粒子である。前記金属元素の例は、Be、Mg、Ca、Sr、Ba、Y、Ti、Zr、Zn、及びAlを包含する。
(B3)の具体例は、3A12O3・2SiO2、2MgO・SiO2、ZrO2・SiO2、及びMgO・SiO2からなる群より選ばれる少なくとも1種の無機酸化物の粒子を包含する。
無機酸化物粒子の比誘電率(ε)(25℃、1kHz)は、LCRメーターを用いて容量(C)を測定し、容量、電極面積(S)、焼結体の厚さ(d)から、式C=εε0×S/d(ε0:真空の誘電率)で算出した値である。
無機酸化物粒子の平均一次粒子径は、レーザー回折・散乱式粒度分布測定装置 LA-920(商品名)(堀場製作所社)又はその同等品を用いて算出される。
前記含有量の下限は、電気絶縁性を向上する点から、好ましくは0.1質量部、より好ましくは0.5質量部、更に好ましくは1質量部である。
前記含有量の上限は、無機酸化物粒子を圧電性ポリマー中に均一に分散させ、電気絶縁性(耐電圧)の低下、及び引張強度の低下を防止する点から、好ましくは200質量、より好ましくは150質量部、更に好ましくは100質量部である。
親和性向上剤は、無機酸化物粒子と圧電性ポリマーとの間の親和性を高め、無機酸化物粒子を圧電性ポリマー中に均一に分散させ、無機酸化物粒子と圧電性ポリマーをしっかり結合させ、ボイドの発生を抑制し、及び比誘電率を高めることができる。
有機チタン化合物の好適な例は、無機酸化物粒子との親和性が良好な点から、アルコキシチタニウム、及びチタニウムキレートを包含する。
で表される化合物を包含する。
有機圧電フィルムは、キャストフィルムであることが好ましい。有機圧電フィルムをキャストフィルムで構成することにより、厚さの均一性を高くすることができ、例えば、後述のように膜厚の変動係数を10%以下にすることができる。
有機圧電フィルムは、下記の物性を有することが好ましい。なお、本明細書において、各物性は、特に断りのない限り、測定前の前処理として加熱することなく測定した物性を意味し、「110℃で10分加熱した後の」という記載を付加した場合は、前処理として110℃で10分加熱し、その後に測定した物性を意味する。また、110℃で10分加熱する対象は、製造後の有機圧電フィルムであることができ、例えば、後述の工程A~工程Cを含む方法により有機圧電フィルムを製造する場合、工程Cの後の有機圧電フィルムを対象とする。
一実施態様において、有機圧電フィルムは、少なくとも、下記全光線透過率と、下記単位膜厚あたりの内部ヘイズ値と、下記110℃で10分加熱した後の圧電定数d33とを有することが好ましい。他の実施態様において、有機圧電フィルムは、少なくとも、下記結晶サイズ(特に結晶平均長)と、下記110℃で10分加熱した後の圧電定数d33とを有することが好ましい。さらに他の実施態様において、有機圧電フィルムは、少なくとも、下記単位膜厚あたりの内部ヘイズ値の変化率と、下記圧電定数d33の変化率とを有することが好ましい。
これらの実施態様において、有機圧電フィルムは、さらに、下記膜厚、下記リタデーション、下記YI値、下記残留分極量、及び下記結晶化度からなる群より選択される少なくとも一種の物性を有することが好ましい。当該有機圧電フィルムは、さらに、下記圧電定数d33の変動係数、下記膜厚の変動係数、及び下記面積からなる群より選択される少なくとも一種の物性を有することも好ましい。
<全光線透過率の決定方法>
本明細書において、「全光線透過率」は、JIS K-7361に準拠し、ヘイズメーター NDH-7000SP(製品名、日本電色工業社)又はその同等品を使用して測定することができる。
全光線透過率の上限は、特に限定されないが、例えば、99.99%、99.9%、又は99%であることができる。110℃で10分加熱した後の全光線透過率の上限も、同様の値に設定することができる。
全光線透過率は、好ましくは90%以上(例:90~99.99%の範囲内)、より好ましくは91%以上(例:91~99.99%の範囲内)、さらに好ましくは92%以上(例:92~99.99%の範囲内)である。110℃で10分加熱した後の全光線透過率の範囲も、同様の範囲に設定することができる。
<内部へイズ値の決定方法>
本明細書において、「内部ヘイズ値」(inner haze)は、JIS K-7361に準拠し、ヘイズメーター NDH-7000SP(製品名、日本電色工業社)又はその同等品を使用したヘイズ(HAZE、濁度)試験において、ガラス製セルの中に水を入れて、その中にフィルムを挿入し、ヘイズ値を測定することにより得られる。
110℃で10分加熱した後の内部ヘイズ値の上限は、透明性の点から、好ましくは7%、より好ましくは6.5%、さらに好ましくは6%である。また、110℃で10分加熱した後の内部ヘイズ値の上限は、さらに低い値に設定することができ、例えば、5.5%、5%、4.5%、4%、3.5%、3%、2.5%、2%、1.5%、又は1%であることができる。
内部ヘイズ値の下限は、特に限定されないが、例えば、0.01%、0.05%、又は0.1%であることができる。110℃で10分加熱した後の内部ヘイズ値の下限も、同様の値に設定することができる。
内部ヘイズ値は、好ましくは6%以下(例:0.01~6%の範囲内)、より好ましくは5.5%以下(例:0.01~5.5%の範囲内)、さらに好ましくは5%以下(例:0.01~5%の範囲内)である。
110℃で10分加熱した後の内部ヘイズ値は、好ましくは7%以下(例:0.01~7%の範囲内)、より好ましくは6.5%以下(例:0.01~6.5%の範囲内)、さらに好ましくは6%以下(例:0.01~6%の範囲内)である。
内部ヘイズ値がこのような範囲内にあっても、高圧電性を発揮することができる。
本明細書において、「内部ヘイズ値の変化率」は、式:((110℃で10分加熱した後の内部ヘイズ値)-(内部ヘイズ値))/(内部ヘイズ値)×100により求められる値の絶対値を意味する。
内部ヘイズ値の変化率の上限は、熱安定性の点から、好ましくは140%、より好ましくは120%、さらに好ましくは100%、さらにより好ましくは90%である。また、内部ヘイズ値の変化率の上限は、さらに低い値に設定することができ、例えば、80%、70%、60%、又は50%であることができる。
内部ヘイズ値の変化率の下限は、特に限定されないが、例えば、1%、2%、3%、4%、又は5%である。
内部ヘイズ値の変化率は、好ましくは140%以下(例:1~140%の範囲内)、より好ましくは120%以下(例:1~120%の範囲内)、さらに好ましくは100%以下(例:1~100%の範囲内)である。
内部ヘイズ値[%]/膜厚[μm]の比の上限は、透明性の点から、好ましくは0.2、より好ましくは0.15、さらに好ましくは0.1、特に好ましくは0.05である。110℃で10分加熱した後の内部ヘイズ値[%]/膜厚[μm]の比の上限も、同様の値に設定することができる。
内部ヘイズ値[%]/膜厚[μm]の比の下限は、特に限定されないが、例えば、0.0001、0.0005、0.001、又は0.005であることができる。110℃で10分加熱した後の内部ヘイズ値[%]/膜厚[μm]の比の下限も、同様の値に設定することができる。
内部ヘイズ値[%]/膜厚[μm]の比は、好ましくは0.2以下(例:0.0001~0.2の範囲内)、より好ましくは0.15以下(例:0.0001~0.15の範囲内)、さらに好ましくは0.1以下(例:0.0001~0.1の範囲内)である。110℃で10分加熱した後の内部ヘイズ値[%]/膜厚[μm]の比の範囲も、同様の範囲に設定することができる。
当該比がこのような範囲内にあっても、高圧電性を発揮することができる。
本明細書において、「内部ヘイズ値[%]/膜厚[μm]の比の変化率」は、当該比をrとしたとき、式:((110℃で10分加熱した後のr値)-(r値))/(r値)×100により求められる値の絶対値を意味する。
r値の変化率の上限は、熱安定性の点から、好ましくは140%、より好ましくは120%、さらに好ましくは100%、さらにより好ましくは90%である。また、r値の変化率の上限は、さらに低い値に設定することができ、例えば、80%、70%、60%、又は50%であることができる。
r値の変化率の下限は、特に限定されないが、例えば、1%、2%、3%、4%、又は5%である。
r値の変化率は、好ましくは140%以下(例:1~140%の範囲内)、より好ましくは120%以下(例:1~120%の範囲内)、さらに好ましくは100%以下(例:1~100%の範囲内)である。
<圧電定数d33の決定方法>
本明細書において、「圧電定数d33」は、PIEZOTEST社のピエゾメーターシステムPM300又はその同等品を用いて、1.0N、110Hzの力を加えることにより測定される。恣意性を排除して選択したフィルム上の10点において圧電定数d33を測定し、その算術平均値を圧電定数d33とすることができる。フィルム上で恣意性を排除して10点を選択することは、例えば、直線上で50mm間隔に10点を選択することにより行うことができる。ここで、恣意性とは、後記する変動係数が小さくなるように意図することを意味する。圧電定数d33の実測値は、測定されるフィルムの表裏によって、プラスの値、又はマイナスの値となるが、本明細書中においては、圧電定数d33の値として、その絶対値を記載する。
110℃で10分加熱した後の圧電定数d33の下限は、好ましくは10pC/N、より好ましくは11pC/N、さらに好ましくは12pC/N、さらにより好ましくは13pC/Nである。
圧電定数d33の上限は、特に限定されないが、例えば、100pC/N、50pC/N、35pC/N、又は30pC/Nであることができる。110℃で10分加熱した後の圧電定数d33の上限も、同様の値に設定することができる。
圧電定数d33は、好ましくは13pC/N以上(例:13~100pC/Nの範囲内)、より好ましくは14pC/N以上(例:14~100pC/Nの範囲内)、さらに好ましくは15pC/N以上(例:15~100pC/Nの範囲内)である。
110℃で10分加熱した後の圧電定数d33は、好ましくは10pC/N以上(例:10~100pC/Nの範囲内)、より好ましくは11pC/N以上(例:11~100pC/Nの範囲内)、さらに好ましくは12pC/N以上(例:12~100pC/Nの範囲内)である。
圧電定数d33がこのような範囲内にあっても、高透明性を発揮することができる。
本明細書において、「圧電定数d33の変化率」は、式:((110℃で10分加熱した後のd33)-(d33))/(d33)×100により求められる値の絶対値を意味する。
圧電定数d33の変化率の上限は、熱安定性の点から、好ましくは50%、より好ましくは45%、さらに好ましくは40%である。また、圧電定数d33の変化率の上限は、さらに低い値に設定することができ、例えば、35%、30%、25%、20%、又は15%であることができる。
圧電定数d33の変化率の下限は、特に限定されないが、例えば、0.5%又は1%である。
圧電定数d33の変化率は、好ましくは50%以下(例:0.5~50%の範囲内)、より好ましくは45%以下(例:0.5~45%の範囲内)、さらに好ましくは40%以下(例:0.5~40%の範囲内)である。
圧電定数d33の変動係数は、圧電定数d33の、算術平均に対する標準偏差の比である。
圧電定数d33の変動係数の下限は、製造コストの点から、好ましくは0.01である。
圧電定数d33の変動係数は、好ましくは2以下(例:0.01~2の範囲内)、より好ましくは1.5以下(例:0.01~1.5の範囲内)、さらに好ましくは1以下(例:0.01~1の範囲内)である。
<リタデーションの決定方法>
本明細書において、「リタデーション」は、フィルムのサンプルを2cm×2cm以上の大きさに切り出して、位相差フィルム・光学材料検査装置RETS-100(製品名、大塚電子)又はその同等品を用いた測定によって、決定される。本明細書において、リタデーションの数値としては、550nmの値を採用する。
リタデーションの下限は、特に限定されないが、例えば、0.1nm、0.5nm、又は1nmであることができる。
リタデーションは、好ましくは0.1~100nmの範囲内、より好ましくは0.5~50nmの範囲内、さらに好ましくは1~30nmの範囲内であることができる。
リタデーション[nm]/膜厚[μm]の比の上限は、光学特性の点から、好ましくは10、より好ましくは5、さらに好ましくは1、さらにより好ましくは0.5である。
リタデーション[nm]/膜厚[μm]の比の下限は、特に限定されないが、例えば、0.01、0.02、0.03、0.04、0.05、又は0.1であることができる。
リタデーション[nm]/膜厚[μm]の比は、好ましくは0.01~10の範囲内、より好ましくは0.01~1の範囲内、さらに好ましくは0.01~0.5の範囲内である。
<結晶化度の決定方法>
開口部が設けられたサンプルホルダにフィルム試料を直接載置し、回折角2θが10~40°である範囲にわたってX線回折測定を行ったときに得られるX線回折パターンにおいて、
10°の回折角2θにおける回折強度と、25°の回折角2θにおける回折強度とを結ぶ直線をベースラインとして設定し、及び
当該ベースラインと回折強度曲線とで囲まれる領域を、プロファイルフィッティングにより2つの対称性ピークに分離し、
このうち、回折角2θの大きい方を結晶性ピークと認定し、且つ回折角2θの小さい方を非晶性ハローピークと認定した場合に、
100×(結晶性ピークの面積)/(結晶性ピークの面積と非晶性ハローピークの面積との和)で表される値を結晶化度とする。
結晶化度の上限は、例えば、99%、95%、又は90%であることができる。110℃で10分加熱した後の結晶化度の上限も、同様の値に設定することができる。
結晶化度は、好ましくは40%以上(例:40~99%の範囲内)、より好ましくは50%以上(例:50~99%の範囲内)、さらに好ましくは60%以上(例:60~99%の範囲内)である。110℃で10分加熱した後の結晶化度の範囲も、同様の範囲に設定することができる。
結晶化度がこのような範囲であっても、高透明性を発揮することができる。
本明細書において、YI値は、JIS K7105に準拠して測定した黄色度をいう。本明細書において、YI値は、フィルムのサンプルを2cm×2cm以上の大きさに切り出して、分光測色計(CM-5、コニカミノルタ製)又はその同等品を用いた透過測定によって、決定される。
YI値の上限は、好ましくは4、より好ましくは3、さらに好ましくは2である。110℃で10分加熱した後のYI値の上限も、同様の値に設定することができる。
YI値の下限は、特に限定されないが、例えば、0.1又は0.2であることができる。110℃で10分加熱した後のYI値の下限も、同様の値に設定することができる。
YI値は、好ましくは4以下(例:0.1~4の範囲内)、より好ましくは3以下(例:0.1~3の範囲内)、さらに好ましくは2以下(例:0.1~2の範囲内)である。110℃で10分加熱した後のYI値の範囲も、同様の範囲に設定することができる。
本明細書において、「YI値の変化率」は、式:((110℃で10分加熱した後のYI値)-(YI値))/(YI値)×100により求められる値の絶対値を意味する。
YI値の変化率の上限は、熱安定性の点から、好ましくは150%、より好ましくは100%、さらに好ましくは90%、さらにより好ましくは80%、特に好ましくは70%である。
YI値の変化率の下限は、特に限定されないが、例えば、1%又は5%である。
YI値の変化率は、好ましくは150%以下(例:1~150%の範囲内)、より好ましくは100%以下(例:1~100%の範囲内)、さらに好ましくは80%以下(例:1~80%の範囲内)である。
<残留分極量の決定方法>
試料フィルムは、20mm×20mmに切り出したフィルムの中央部5mm×5mmに、アルミニウム電極(平面電極)を真空加工蒸着によりパターニングし、この平面電極に、絶縁テープを貼り付けて補強したアルミニウム箔製の2本のリード(3mm×80mm)の電極を導電性両面テープで接着することにより得られる。この試料フィルム、ファンクションジェネレーター、高圧アンプ、及びオシロスコープをソーヤータワー回路に組み込み、三角波を試料フィルムに印加(最大±10kV)し、試料フィルムの応答を、オシロスコープを用いて測定することにより、印加電界80MV/mにおける残留分極量が得られる。
残留分極量の上限は、特に限定されないが、例えば、200mC/m2、150mC/m2、100mC/m2、90mC/m2、80mC/m2、又は70mC/m2である。
残留分極量は、好ましくは30mC/m2以上(例:30~200mC/m2、又は30~100mC/m2の範囲内)、より好ましくは40mC/m2以上(例:40~90mC/m2の範囲内)、さらに好ましくは50mC/m2以上(例:50~80mC/m2の範囲内)である。
結晶サイズは、特に限定されない。有機圧電フィルムは、針状又は繊維状の結晶を含有することが好ましく、下記の平均結晶長、平均結晶幅、及び/又は最大結晶長を有することが好ましい。
<平均結晶長、平均結晶幅、及び最大結晶長の決定方法>
フィルム試料表面の走査型電子顕微鏡(Scanning Electron Microscope:SEM)像を観察する。構成する針状結晶の大きさに応じて1万~10万倍の範囲内から選択される倍率で電子顕微鏡画像による観察を行う。ただし、試料、観察条件、及び倍率は下記の条件(1)及び(2)を満たすように調整する。
(1)観察画像内の任意箇所に一本の直線Xを引き、この直線Xに対し、20本以上の針状結晶が交差する。
(2)同じ観察画像内で直線Xと垂直に交差する直線Yを引き、直線Yに対し、20本以上の針状結晶が交差する。
得られた電子顕微鏡観察画像に対して、直線Xに交錯する針状結晶、直線Yに交錯する針状結晶の各々について少なくとも20本(すなわち、合計が少なくとも40本)の結晶長(長径)及び結晶幅(短径)を読み取る。このような電子顕微鏡画像を少なくとも3組以上観察し、少なくとも40本×3組(すなわち、少なくとも120本)の結晶長及び結晶幅を読み取る。このように読み取った結晶長及び結晶幅を平均して平均結晶長及び平均結晶幅を求め、読み取った結晶長の最も長いものを最大結晶長とする。
平均結晶長の下限は、特に限定されないが、例えば、1nm、5nm、10nm、120nm、30nm、40nm、又は50nmである。
平均結晶長は、好ましくは450nm以下(例:1~450nmの範囲内)、より好ましくは300nm以下(例:1~300nmの範囲内)、さらに好ましくは200nm以下(例:1~200nmの範囲内)である。
最大結晶長の下限は、特に限定されないが、例えば、10nmである。
最大結晶長は、好ましくは800nm以下(例:10~800nmの範囲内)、より好ましくは600nm以下(例:10~600nmの範囲内)、さらに好ましくは380nm以下(例:10~380nmの範囲内)である。
平均結晶幅の下限は、特に限定されないが、例えば、1nmである。
平均結晶幅は、好ましくは100nm以下(例:1~100nmの範囲内)、より好ましくは80nm以下(例:1~80nmの範囲内)、さらに好ましくは60nm以下(例:1~60nmの範囲内)である。
<膜厚の決定方法>
本明細書中、フィルムの平面方向の全体に渡って1cm四方毎に10箇所において、光電式デジタル測長システム(デジマイクロMH-15M、Nikon社製)又はその同等品を用いて厚さを測定し、その平均値を膜厚とする。
膜厚の上限は、特に限定されないが、可撓性を得る観点から好ましくは、例えば、1000μm、900μm、又は800μmであることができる。
膜厚は、自立膜として使用し得る観点から好ましくは1μm以上(例:1~1000μmの範囲内)、より好ましくは5μm以上(例:5~1000μmの範囲内)、さらに好ましくは10μm以上(例:10~1000μmの範囲内)である。ガラスやPETフィルムなどの支持体上に形成する場合は好ましくは10nm以上(例:10nm~1000μmの範囲内)、より好ましくは30nm以上(例:30nm~1000μmの範囲内)、さらに好ましくは50nm以上(例:50nm~1000μmの範囲内)である。
<膜厚の変動係数の決定方法>
本明細書中、フィルムの平面方向の全体に渡って1cm四方毎に10箇所において測定した値の変動係数を、膜厚の変動係数とする。
膜厚の変動係数の下限は、特に限定されないが、例えば、0.01%、0.05%、又は0.1%であることができる。
膜厚の変動係数は、好ましくは10%以下(例:0.01~10%の範囲内)、さらに好ましくは5%(例:0.01~5%の範囲内)である。
面積の下限は、特に限定されないが、工業生産性の点から、好ましくは9cm2、さらに好ましくは10cm2である。面積の下限は、さらに高い値に設定することができ、例えば、50cm2、100cm2、200cm2、300cm2、400cm2、又は500cm2であることができる。微細面積へ印刷や塗布を行う場合はこの限りではなく、面積の下限は、例えば、0.1μm2、1μm2、10μm2、50μm2、又は100μm2であることができる。
面積の上限は、特に限定されないが、例えば、4000m2、3000m2、2000m2、1000m2、又は500m2であることができる。微細面積へ印刷や塗布を行う場合はこの限りではなく、面積の上限は、例えば、10mm2、5mm2、又は1mm2であることができる。
面積は、好ましくは9cm2以上(例:9cm2~4000m2の範囲内)、さらに好ましくは10cm2以上(例:10cm2~4000m2の範囲内)である。当該範囲は、ロール・トゥ・ロール方式で製造される面積の範囲に対応する。
(a)全光線透過率が90%以上、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(b)全光線透過率が90%以上、内部へイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(c)全光線透過率が90%以上、内部へイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、及び110℃10分加熱した後の圧電定数d33が10pC/N以上;
(d)全光線透過率が90%以上、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、単位膜厚あたりのリタデーションが0.01~10nm/μmの範囲内、及び膜厚が1~1000μmの範囲内;
(e)全光線透過率が90%以上、内部へイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、リタデーションが100nm以下、及び膜厚が1~1000μmの範囲内;
(f)全光線透過率が90%以上、内部へイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、リタデーションが100nm以下、単位膜厚あたりのリタデーションが0.01~10nm/μmの範囲内、及び膜厚が1~1000μmの範囲内;
(g)全光線透過率が90%以上、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及びYI値が4以下;
(h)全光線透過率が90%以上、内部へイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及びYI値が4以下;
(i)全光線透過率が90%以上、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及び残留分極量40mC/m2以上;
(j)全光線透過率が90%以上、内部ヘイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及び残留分極量40mC/m2以上;
(k)全光線透過率が90%以上、単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及び結晶化度が40%以上;
(l)全光線透過率が90%以上、内部ヘイズ値(又は110℃で10分加熱した後の内部へイズ値)が6%以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及び結晶化度が40%以上;
(m)最大結晶長が800nm以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(n)平均結晶長が450nm以下、最大結晶長が800nm以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(o)最大結晶長が800nm以下、平均結晶幅が100nm以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(p)平均結晶長が200nm以下、最大結晶長が800nm以下、平均結晶幅が100nm以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(q)最大結晶長が800nm以下、平均結晶幅が100nm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及び結晶化度が40%以上;
(r)平均結晶長が200nm以下、最大結晶長が800nm以下、平均結晶幅が100nm以下、110℃で10分加熱した後の圧電定数d33が10pC/N以上、及び結晶化度が40%以上;
(s)単位膜厚あたりの内部ヘイズ値の変化率が100%以下、110℃で10分加熱した後の単位膜厚あたりの内部ヘイズ値が0.2%/μm以下、圧電定数d33の変化率が40%以下、及び110℃で10分加熱した後の圧電定数d33が10pC/N以上;
(t)最大結晶長が800nm以下、及び結晶化度が40%以上;
(u)平均結晶長が450nm以下、最大結晶長が800nm以下、及び結晶化度が40%以上;
(v)最大結晶長が800nm以下、平均結晶幅が100nm以下、及び結晶化度が40%以上;
(w)平均結晶長が450nm以下、最大結晶長が800nm以下、平均結晶幅が100nm以下、及び結晶化度が40%以上。
本開示の有機圧電フィルムは、各種用途に適用することができる。用途の具体例は、センサ(例:タッチセンサ、振動センサ、生体センサ、タイヤセンサ(タイヤ内面に設置するセンサ))、アクチュエータ、タッチパネル、ハプティックデバイス(ユーザに触覚をフィードバックする機能を有するデバイス)、振動発電装置(例:振動発電床、振動発電タイヤ)、スピーカー、及びマイクを包含する。
本開示の有機圧電フィルムは、例えば、
キャスティング法により、圧電性ポリマーを含有する非分極フィルム(例:無延伸かつ非分極フィルム)を調製する工程A;
非分極フィルム(例:無延伸かつ非分極フィルム)を分極処理する工程B;及び
非分極フィルム(例:無延伸かつ非分極フィルム)を熱処理する、又は工程Bに対して任意の時点でフィルムを熱処理する工程C
の少なくとも1つの工程を含む製造方法、好ましくは、
工程A~Cを含む製造方法
によって製造できる。
キャスティング法による非分極フィルムの製造方法は、例えば、
(A1)圧電性ポリマー(例:フッ化ビニリデン系重合体)、並びに前記所望による成分(例:無機酸化物粒子、及び親和性向上剤)を溶媒中に溶解又は分散させて液状組成物を溶解させて、液状組成物を調製する工程;
(A2)前記液状組成物を基材上に適用(流延又は塗布)する工程;
(A3)前記液状組成物を適用した基材を第1の温度で加熱して乾燥する工程;及び
(A4)前記第1の温度で加熱した基材を第1の温度よりも高い第2の温度で加熱する工程
を含む製造方法である。これらの工程は、工業生産性の点から、ロール・トゥ・ロール方式で実施するのが好ましい。工程(A3)及び工程(A4)は、第1の温度に曝露するゾーン、及び第1の温度よりも高い第2の温度に曝露するゾーンに順次移送することによって実施してもよい。
第1の温度で加熱する時間(加熱乾燥時間)の下限は、例えば1秒、好ましくは10秒、さらに好ましくは30秒である。加熱乾燥時間の上限は、例えば60分、好ましくは30分、さらに好ましくは10分である。加熱乾燥時間は、例えば、10秒~60分の範囲内、好ましくは30秒~10分の範囲内、さらに好ましくは30秒~10分の範囲内である。
第2の温度は、好ましくは融点又はその近傍の温度である。本明細書において、融点又はその近傍の温度は、(融点-12℃)以上であり、(融点+12℃)以下であることができる。第2の温度は、さらに好ましくは(融点-11℃)以上、(融点-10℃)以上、(融点-9℃)以上、(融点-8℃)以上、(融点-7℃)以上、(融点-6℃)以上、又は(融点-5℃)以上である。また、第2の温度は、さらに好ましくは(融点+11℃)以下、(融点+10℃)以下、(融点+9℃)以下、(融点+8℃)以下、(融点+7℃)以下、(融点+6℃)以下、又は(融点+5℃)以下である。第2の温度は、好ましくは(融点-12℃)~(融点+12℃)の範囲内、より好ましくは(融点-10℃)~(融点+10℃)の範囲内、さらに好ましくは(融点-10℃)~(融点+5℃)の範囲内、又は(融点-5℃)~(融点+5℃)の範囲内である。
第2の温度は、圧電性ポリマーの種類によっても異なるが、好ましくは110℃以上、より好ましくは115℃以上、さらに好ましくは120℃以上、さらにより好ましくは125℃以上である。また、第2の温度は、好ましくは150℃以下、より好ましくは145℃以下、さらに好ましくは140℃以下、さらにより好ましくは135℃以下である。第2の温度は、好ましくは110~150℃の範囲内、より好ましくは120~140℃の範囲内、さらに好ましくは125~135℃の範囲内である。
第2の温度で加熱する時間は、例えば1分以上、好ましくは5分以上、さらに好ましくは10分以上である。また、第2の温度で加熱する時間は、例えば60分以下、好ましくは30分以下である。第2の温度で加熱する時間は、例えば1~60分の範囲内、好ましくは5~60分の範囲内、さらに好ましくは10~60分の範囲内である。
第2の温度で加熱することにより、圧電性ポリマーの結晶が微細化しても、高い結晶性を維持できる。これにより有機圧電フィルムで高い透明性及び圧電性を両立できる。
(A5)前記第2の温度で加熱した基材を第3の温度で加熱する工程
を含んでいてもよい。
第3の温度は、好ましくは結晶化温度又はその近傍の温度である。本明細書において、結晶化温度又はその近傍の温度は、(結晶化温度-12℃)以上であり、(結晶化温度+12℃)以下であることができる。第3の温度は、さらに好ましくは(結晶化温度-11℃)以上、(結晶化温度-10℃)以上、(結晶化温度-9℃)以上、(結晶化温度-8℃)以上、(結晶化温度-7℃)以上、(結晶化温度-6℃)以上、(結晶化温度-5℃)以上、(結晶化温度-4℃)以上、又は(結晶化温度-3℃)以上である。また、第3の温度は、さらに好ましくは(結晶化温度+11℃)以下、(結晶化温度+10℃)以下、(結晶化温度+9℃)以下、(結晶化温度+8℃)以下、(結晶化温度+7℃)以下、(結晶化温度+6℃)以下、(結晶化温度+5℃)以下、(結晶化温度+4℃)以下、又は(結晶化温度+3℃)以下である。第3の温度は、好ましくは(結晶化温度-10℃)~(結晶化温度+10℃)の範囲内、より好ましくは(結晶化温度-5℃)~(結晶化温度+5℃)の範囲内、さらに好ましくは(結晶化温度-3℃)~(結晶化温度+3℃)の範囲内である。第3の温度は、圧電性ポリマーの種類によっても異なるが、好ましくは108℃以上、より好ましくは110℃以上、さらに好ましくは113℃以上、特に好ましくは115℃以上である。また、第3の温度は、好ましくは128℃以下、より好ましくは125℃以下、さらに好ましくは123℃以下、特に好ましくは121℃以下である。第3の温度は、好ましくは108~128℃の範囲内、より好ましくは113~123℃の範囲内、さらに好ましくは115~121℃の範囲内である。
第3の温度で加熱する時間は、例えば1分以上、好ましくは3分以上、さらに好ましくは5分以上である。また、第3の温度で加熱する時間は、例えば10分以下である。第3の温度で加熱する時間は、例えば1~10分の範囲内、好ましくは3~10分の範囲内である。
第3の温度で加熱することは結晶成長を促進し、加熱による特性変化の抑制、圧電定数の高いフィルムを得る点で好ましい。
一方、第3の温度で加熱することは、得ようとするフィルムに応じて工業生産性の観点を優先し省略してもよい。
分極処理は、慣用の方法によって行うことができ、好ましくはコロナ放電処理によって行われる。
工程Cは、工程Bに対して任意の時点で、必要に応じて行われることが好ましい。すなわち、工程Cは、工程Bの前、工程Bと同時、又は工程Bの後に実施してもよい。工程Cを工程Bの後に行う場合、工程Cの熱処理は、工程Bで得られた分極化フィルム又は工程Bにおいて分極を完了した部分に対して行うことができる。すなわち、工程Bの分極処理を実施しながら、当該分極処理を終えた部分に対して工程Cの熱処理を実施してもよい。
熱処理の温度は、具体的には、好ましくは80℃以上、より好ましくは85℃以上、更に好ましくは90℃以上である。
また、熱処理の温度は、好ましくは170℃以下、より好ましくは160℃以下、更に好ましくは140℃以下である。
また、熱処理の時間の上限は限定されないが、通常、熱処理の時間は60分間以下である。
有機圧電フィルムは、好ましくは、ロールとして保管及び出荷され得る。
本開示の一実施態様の圧電体は、積層体であってもよく、有機圧電フィルム、及び、有機圧電フィルムの少なくとも一方の面上に設けられた電極を備えていてもよい。
前記有機圧電フィルムを準備する工程;及び
前記有機圧電フィルムの少なくとも一方の面上に電極を設ける工程
を含んでいる。
前記熱処理の温度の上限は、(熱処理される分極化フィルムの融点-3℃)、例えば220℃、好ましくは180℃、より好ましくは150℃、更に好ましくは130℃である。
前記熱処理の温度は、例えば25~220℃の範囲内、好ましくは40~130℃の範囲内であることができる。
(条件)
GPC装置:TOSOH AS-8010、CO-8020及び
SIMADZURID-10A
カラム:GMHHR-H 3本
展開溶媒:ジメチルホルムアミド〔DMF〕
試料濃度:0.05質量%
<使用電極>
(1)20mm幅(10mm厚、500mm長)の真鍮棒の中心線上に10mm間隔で電極用針(針状電極)(R=0.06mm)を1列に並べた針状電極棒
(2)(1)と同様に、15mm間隔で電極用針(R=0.06mm)を1列に並べた針状電極棒
(3)直径0.1mmのタングステン製の線状電極(500mm長)
<全光線透過率>
ヘイズメーター NDH-7000SP(製品名、日本電色工業)を使用し、JIS K-7361に準拠し測定した。
<内部ヘイズ値>
石英製セルの中に水を入れ、その中にフィルムを挿入し、NDH-7000SP(製品名、日本電色工業)を使用し、JIS K-7136に準拠し測定した。
<圧電定数d33>
圧電定数d33の測定は、PIEZOTEST社のピエゾメーターシステムPM300を用いて測定した。当該測定では、1Nでサンプルをクリップし、1.0N、110Hzの力を加えた際の発生電荷を読み取った。
<結晶化度>
開口部が設けられたサンプルホルダにフィルム試料を直接載置し、回折角2θが10~40°である範囲にわたってX線回折測定を行った。得られたX線回折パターンにおいて、10°の回折角2θにおける回折強度と、25°の回折角2θにおける回折強度とを結ぶ直線をベースラインとして設定し、及び当該ベースラインと回折強度曲線とで囲まれる領域を、プロファイルフィッティングにより2つの対称性ピークに分離し、このうち、回折角2θの大きい方を結晶性ピークと認定し、且つ回折角2θの小さい方を非晶性ハローピークと認定した。
結晶化度は、100×(結晶性ピークの面積)/(結晶性ピークの面積と非晶性ハローピークの面積との和)により算出した。
<YI値>
YI値は、JIS K7105に準拠して測定した。
<残留分極量>
20mm×20mmに切り出した試料フィルムの中央部5mm×5mmにアルミニウム電極(平面電極)を真空加工蒸着によりパターニングした。この平面電極に、絶縁テープを貼り付けて補強したアルミニウム箔製の2本のリード(3mm×80mm)の電極を、導電性両面テープで平面電極に接着した。この試料フィルム、ファンクションジェネレーター、高圧アンプ、およびオシロスコープをソーヤータワー回路に組み込み、三角波を試料フィルムに印加(最大±10kV)した。試料フィルムの応答を、オシロスコープを用いて測定することにより、印加電界80MV/mにおける残留分極量を求めた。
<リタデーション>
リタデーションは、フィルムのサンプルを2cm×2cm以上の大きさに切り出して、位相差フィルム・光学材料検査装置 RETS-100(製品名、大塚電子)を用いた測定によって、決定した。リタデーションの数値としては、550nmの値を採用した。
<膜厚>
フィルムの平面方向の全体に渡って1cm四方毎に10箇所において膜厚を光電式デジタル測長システム(デジマイクロMH-15M、Nikon社製)を用いて測定し、平均値からフィルムの膜厚を算出した。
<平均結晶長及び最大結晶長>
フィルム試料表面の走査型電子顕微鏡(Scanning Electron Microscope:SEM)像を観察した。構成する針状結晶の大きさに応じて1000~10万倍の範囲内から選択される倍率で電子顕微鏡画像による観察を行った。ただし、試料、観察条件、及び倍率は下記の条件(1)及び(2)を満たすように調整した。
(1)観察画像内の任意箇所に一本の直線Xを引き、この直線Xに対し、20本以上の針状結晶が交差する。
(2)同じ観察画像内で直線Xと垂直に交差する直線Yを引き、直線Yに対し、20本以上の針状結晶が交差する。
得られた電子顕微鏡観察画像に対して、直線Xに交錯する針状結晶、直線Yに交錯する針状結晶の各々について少なくとも20本(すなわち、合計が少なくとも40本)の結晶長(針状結晶の長径)を読み取った。このような電子顕微鏡画像を少なくとも3組以上観察し、少なくとも40本×3組(すなわち、少なくとも120本)の結晶長を読み取った。このように読み取った結晶長を平均して平均結晶長を求め、最も長い結晶長を最大結晶長とした。
<平均結晶幅>
平均結晶幅は、平均結晶長を測定する際に使用した電子顕微鏡観察画像を解析することにより求めた。具体的には、上記の電子顕微鏡観察画像に対して、直線Xに交錯する針状結晶、直線Yに交錯する結晶の各々について少なくとも20本(すなわち、合計が少なくとも40本)の結晶幅(針状結晶の短径)を読み取った。このような電子顕微鏡画像を少なくとも3組以上観察し、少なくとも40本×3組(すなわち、少なくとも120本)の結晶幅を読み取った。このように読み取った結晶幅を平均して平均結晶幅を求めた。
フッ化ビニリデン(VDF)/テトラフルオロエチレン(TFE)共重合体[VDF/TFE=75/25(モル比)、重量平均分子量(Mw)=105万、融点=131.6℃]をメチルエチルケトン(MEK)に溶解させ固形分20wt%の塗料を調製した。その後、バーコーターを用いてPETフィルム上に前記塗料を流延(キャスティング)し、及び80℃で10分加熱乾燥を行って共重合体フィルムを形成し、表1に示す第2の温度で0.5時間処理した。
PETフィルムから共重合体フィルムを剥がしたところ、表1に示す膜厚であった。当該共重合体フィルムについて下記の分極処理を実施した。
分極処理
ISOクラス7のクリーンルーム(湿度20~30%)の中で、図1にその概要を示したように、アースされたステージ1(長さ320mm、幅220mm)であるSUS製のグランド電極を25℃に保ち、このグランド電極上に50mm×50mmに切り出した非分極共重合体フィルム2を設置した。その上に340×240mmのPETフィルム3を、その中央部分が非分極共重合体フィルム2の中央部分を覆うように設置した。上部電極として、共重合体フィルムから10mm上空に離れた位置に10mm間隔で配置された針状電極(第1電極E1)と、1本のタングステンワイヤー(r=0.1mm)からなるワイヤ電極(第2電極E2)をグランド電極の上面に平行になるように渡し、この針状電極、ワイヤ電極に加える直流電圧を0kVから印加電圧である11kV、15kV(トレック社製610Dの高圧電源)にそれぞれ設定した。
ステージ1に配置した非分極共重合体フィルム2を、ステージ1の移動速度3000mm/minで、針状電極E1及びワイヤ電極E2を通過させ分極処理を実施した。得られた分極共重合体フィルムを80℃に保持した乾燥炉に静置し熱処理を行い、有機圧電フィルムを得た。
なお、実施例1及び比較例3の走査型電子顕微鏡像を図2に示す。
第2の温度で加熱した後、さらに表1に示す第3の温度で10分間加熱した以外は、実施例1と同様の手順により、有機圧電フィルムを得た。
フッ化ビニリデン(VDF)/テトラフルオロエチレン(TFE)共重合体[VDF/TFE=80/20(モル比)、重量平均分子量(Mw)=23万、融点=124.9℃]をメチルエチルケトン(MEK)に溶解させ固形分20wt%の塗料を調製した。それ以降は実施例1と同様の手順により、有機圧電フィルムを得た。
フッ化ビニリデン(VDF)/テトラフルオロエチレン(TFE)共重合体[VDF/TFE=67/33(モル比)、重量平均分子量(Mw)=67万、融点=146.8℃]をメチルエチルケトン(MEK)に溶解させ固形分20wt%の塗料を調製した。それ以降は実施例1~6と同様の手順により、有機圧電フィルムを得た。
フッ化ビニリデン(VDF)/テトラフルオロエチレン(TFE)共重合体[VDF/TFE=74/26(モル比)、重量平均分子量(Mw)=73万、融点=133.4℃]をメチルエチルケトン(MEK)に溶解させ固形分14wt%の塗料を調製した。その後、当該塗料をフィルターで濾過し、当該濾液をPETフィルム上にダイコーターで塗布した。さらに乾燥を行うことによって、PETフィルム上に共重合体フィルムを形成した。この際、前記乾燥は、4つのゾーン(1ゾーンあたり2m)の乾燥温度をそれぞれ80℃/100℃/129℃/129℃に設定した乾燥炉において行った。
PETフィルムから共重合体フィルムを剥がしたところ、表1に示す膜厚であった。当該共重合体フィルムについて線状電極を用いてロール・トゥ・ロールで連続印加を行い分極処理を実施した。それ以降は実施例1と同様の手順により、有機圧電フィルムを得た。
フッ化ビニリデン(VDF)/テトラフルオロエチレン(TFE)共重合体[VDF/TFE=80/20(モル比)、重量平均分子量(Mw)=23万、融点=124.9℃]をメチルエチルケトン(MEK)に溶解させ固形分20wt%の塗料を調製した。それ以降は実施例7と同様の手順により、有機圧電フィルムを得た。
Claims (15)
- 全光線透過率が90%以上であり、
単位膜厚あたりの内部ヘイズ値が0.2%/μm以下であり、
110℃で10分加熱した後の圧電定数d33が10pC/N以上である、
有機圧電フィルム。 - フッ化ビニリデン系共重合体フィルムからなる、請求項1に記載の有機圧電フィルム。
- 前記フッ化ビニリデン系共重合体が、フッ化ビニリデン/テトラフルオロエチレン共重合体、及びフッ化ビニリデン/トリフルオロエチレン共重合体からなる群より選択される少なくとも一種である、請求項2に記載の有機圧電フィルム。
- 前記フッ化ビニリデン系共重合体において、フッ化ビニリデンの組成比率が60~85モル%の範囲内である、請求項2又は3に記載の有機圧電フィルム。
- 膜厚が10nm~1000μmである、請求項1~4のいずれか一項に記載の有機圧電フィルム。
- リタデーションが500nm以下である、請求項1~5のいずれか一項に記載の有機圧電フィルム。
- YI値が4以下である、請求項1~6のいずれか一項に記載の有機圧電フィルム。
- 残留分極量が40mC/m2以上である、請求項1~7のいずれか一項に記載の有機圧電フィルム。
- 開口部が設けられたサンプルホルダにフィルム試料を直接載置し、回折角2θが10~40°である範囲にわたってX線回折測定を行ったときに得られるX線回折パターンにおいて、
10°の回折角2θにおける回折強度と、25°の回折角2θにおける回折強度とを結ぶ直線をベースラインとして設定し、及び
当該ベースラインと回折強度曲線とで囲まれる領域を、プロファイルフィッティングにより2つの対称性ピークに分離し、
このうち、回折角2θの大きい方を結晶性ピークと認定し、且つ回折角2θの小さい方を非晶性ハローピークと認定した場合に、
100×(結晶性ピークの面積)/(結晶性ピークの面積と非晶性ハローピークの面積との和)で表される結晶化度が40%以上である、請求項1~8のいずれか一項に記載の有機圧電フィルム。 - 針状の結晶を含有するフッ化ビニリデン系共重合体フィルムからなり、
最大結晶長が800nm以下であり、
110℃で10分加熱した後の圧電定数d33が10pC/N以上である、
有機圧電フィルム。 - 平均結晶長が450nm以下である、請求項10に記載の有機圧電フィルム。
- 開口部が設けられたサンプルホルダにフィルム試料を直接載置し、回折角2θが10~40°である範囲にわたってX線回折測定を行ったときに得られるX線回折パターンにおいて、
10°の回折角2θにおける回折強度と、25°の回折角2θにおける回折強度とを結ぶ直線をベースラインとして設定し、及び
当該ベースラインと回折強度曲線とで囲まれる領域を、プロファイルフィッティングにより2つの対称性ピークに分離し、
このうち、回折角2θの大きい方を結晶性ピークと認定し、且つ回折角2θの小さい方を非晶性ハローピークと認定した場合に、
100×(結晶性ピークの面積)/(結晶性ピークの面積と非晶性ハローピークの面積との和)で表される結晶化度が40%以上である、請求項10又は11に記載の有機圧電フィルム。 - センサ、アクチュエータ、タッチパネル、ハプティックデバイス、振動発電装置、スピーカー、及びマイクからなる群より選択される1種以上に使用するための、請求項1~12のいずれか一項に記載の有機圧電フィルム。
- 積層体であり、
請求項1~12のいずれか一項に記載の有機圧電フィルム、及び
前記有機圧電フィルムの少なくとも一方の面上に設けられた電極を備える圧電体。 - キャスティング法により無延伸かつ非分極のフッ化ビニリデン系重合体フィルムを調製する工程A;
前記無延伸かつ非分極のフッ化ビニリデン系重合体フィルムを分極処理する工程B;及び
工程Bに対して任意の時点で、無延伸のフッ化ビニリデン系重合体フィルムを熱処理する工程C
を含む有機圧電フィルムの製造方法であって、
工程Aが、フッ化ビニリデン系重合体の融点をT℃としたとき、(T-10)℃~(T+5)℃の範囲内で加熱する工程A3を含む、有機圧電フィルムの製造方法。
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JP2011181748A (ja) | 2010-03-02 | 2011-09-15 | Daikin Industries Ltd | 分極化樹脂フィルムの製造方法 |
WO2015064328A1 (ja) * | 2013-10-29 | 2015-05-07 | ダイキン工業株式会社 | 圧電フィルム |
JP2016219804A (ja) | 2015-05-22 | 2016-12-22 | ダイキン工業株式会社 | 有機圧電フィルム |
WO2020080382A1 (ja) * | 2018-10-16 | 2020-04-23 | ダイキン工業株式会社 | 圧電フィルム |
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KR20240051226A (ko) | 2024-04-19 |
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