Organic Piezoelectric Film

Abstract

An object of the present invention is to provide an organic piezoelectric film having particularly small in-plane variation in piezoelectricity. Piezoelectric constant d 33 An organic piezoelectric film having a coefficient of variation of 50% or less.

Description

[Technical field]

[0001] The present invention relates to an organic piezoelectric film. [Background technology]

[0002] 2. Description of the Related Art Conventionally, various organic piezoelectric films and inorganic dielectric films are known as films or membranes having piezoelectricity. Among them, organic piezoelectric films have the advantage of being flexible, unlike inorganic dielectric films, and therefore can be used in a variety of applications. For example, Patent Document 1 discloses a polarized vinylidene fluoride / tetrafluoroethylene copolymer film for use in touch panels or for detecting touch pressure as a piezoelectric film.

[0003] In recent years, an increasing number of electronic devices are being equipped with touch panels instead of mechanical buttons as input members due to their superior operability. However, mechanical buttons have the disadvantage that users cannot get the same operational feel as when they move a button, whereas touch panels have the disadvantage that users cannot get the same operational feel as when they move a button. In order to overcome such disadvantages, a touch panel equipped with a flexible piezoelectric actuator has been proposed that provides tactile feedback to a user who operates the touch panel (for example, Patent Document 2). Such devices that use technology for providing tactile feedback to a user who operates a touch panel are generally called haptic devices.

[0004] On the other hand, mobile electronic devices such as smartphones and tablets are equipped with secondary batteries because they are carried by users. In order to reduce the frequency of charging, a vibration power generation device using a piezoelectric element that can be used in such electronic devices has been proposed (Patent Document 3).

[0005] Piezoelectric films are piezoelectric elements that are easy to process and form into thin films with large areas, and compared to conventional ceramic piezoelectric elements, they can be used to fabricate dynamic pressure sensors with large areas and high voltage sensitivity. For example, they can be used as pressure sensors to detect the load applied to elastic supports such as beds, mats, and sheets, and to determine the presence or absence of people, animals, objects, etc.

[0006] In recent years, research into flexible displays using flexible substrates such as plastics has progressed. As an example of such a flexible display substrate, Patent Document 4 discloses a flexible display substrate in which a gas barrier layer and a transparent conductive layer are laminated on a transparent plastic film. Flexible displays are superior to displays using conventional glass substrates in terms of light weight, thinness, flexibility, etc., and therefore can be installed on curved surfaces such as cylinders. Furthermore, they can be rolled up for storage, so portability is not compromised even with a large screen. Due to these advantages, flexible displays are attracting attention for use in, for example, advertisement displays and display devices such as PDAs (personal digital assistants). When such a flexible display is used as an image display device and sound generating device that reproduces sound along with images, such as a television receiver, a speaker, which is an acoustic device for generating sound, is required. Conventional speaker shapes are generally a funnel-shaped so-called cone type and a spherical dome type. However, if these speakers are built into the flexible display, there is a risk that the advantages of the flexible display, such as light weight and flexibility, will be lost. On the other hand, if the speaker is attached externally, it will be difficult to carry around. However, there are some disadvantages to this, such as the difficulty of installing the device on a curved wall and the loss of aesthetic appeal. In this context, for example, Patent Document 5 discloses the use of a sheet-like flexible piezoelectric film as a speaker that can be integrated into a flexible display without compromising its light weight and flexibility. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2011-222679 A [Patent Document 2] JP 2003-288158 A [Patent Document 3] JP 2011-97661 A [Patent Document 4] JP 2000-338901 A [Patent Document 5] JP 2008-294493 A Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, there has been a demand for larger touch panels, and therefore, in a touch panel capable of detecting touch pressure, it is desirable for the piezoelectric film used for detecting touch pressure to also have a large screen. However, when conventional piezoelectric films are used in such large-screen touch panels, the in-plane variation in piezoelectricity is not sufficiently small. Specifically, if the in-plane variation in piezoelectricity of an organic piezoelectric film used in a touch panel capable of detecting touch pressure (especially a large-screen touch panel) is not small enough, even with the same pressure, the electrical signal generated will vary depending on the touch position, resulting in the device determining that the pressure is different and causing a malfunction.

[0009] Furthermore, when conventional piezoelectric films are used in haptic devices, the in-plane variation in piezoelectricity is not sufficiently small. Specifically, if the in-plane variation in piezoelectricity of the organic piezoelectric film used in a haptic device is not small enough, variation will occur in the tactile feedback, preventing a stable operating feel, leading to operational errors and malfunctions of the device.

[0010] Furthermore, when conventional piezoelectric films are used in vibration power generation devices, the in-plane variation in piezoelectricity is not sufficiently small. Specifically, if the in-plane variation in piezoelectricity of the organic piezoelectric film used in the vibration power generation device is not small enough, a constant and stable amount of power generation cannot be obtained even if the amount of vibration is the same.

[0011] Furthermore, if the in-plane variation in piezoelectricity of an organic piezoelectric film used in a pressure sensor (especially a large-area pressure sensor) is not small enough, even with the same pressure, the generated electrical signal will vary depending on the position where the pressure is applied, resulting in unstable sensing.

[0012] Furthermore, if the in-plane variation in piezoelectricity of an organic piezoelectric film used in a flat speaker (especially a large-area flat speaker) is not small enough, the sound generated will vary depending on the location on the surface, resulting in a problem of degraded sound quality.

[0013] Therefore, an object of the present invention is to provide an organic piezoelectric film having particularly small in-plane variation in piezoelectricity. [Means for solving the problem]

[0014] As a result of extensive investigation, the present inventors have found that Piezoelectric constant d 33 The inventors have found that the above problems can be solved by an organic piezoelectric film having a coefficient of variation of 50% or less, and have thus completed the present invention.

[0015] The present invention includes the following aspects.

[0016] Section 1. Piezoelectric constant d 33 The organic piezoelectric film has a coefficient of variation of 2.0 or less. Section 2. Piezoelectric constant d 33 Item 3. The organic piezoelectric film according to item 1, wherein the resistivity is in the range of 0.5 to 30 pC / N. Piezoelectric constant d 33 Item 2. The organic piezoelectric film according to item 1, wherein the resistivity is within a range of 0.5 to less than 2.0 pC / N. Section 4. Piezoelectric constant d 33 2. The organic piezoelectric film according to item 1, wherein the variation coefficient is within a range of 2.0 to less than 4.0 pC / N and is 1.0 or less. Section 5. Piezoelectric constant d 33 2. The organic piezoelectric film according to item 1, wherein the piezoelectric constant is in the range of 4.0 to less than 6.0 pC / N and the variation coefficient is 0.6 or less. Section 6. Piezoelectric constant d 33 2. The organic piezoelectric film according to item 1, wherein the piezoelectric constant is in the range of 6.0 to less than 10.0 pC / N and the variation coefficient is 0.4 or less. Section 7. Piezoelectric constant d 33 2. The organic piezoelectric film according to item 1, wherein the piezoelectric constant is in the range of 10.0 to less than 14.0 pC / N and the variation coefficient is 0.3 or less. Section 8. Piezoelectric constant d 33 2. The organic piezoelectric film according to item 1, wherein the piezoelectric constant is in the range of 14.0 to 30.0 pC / N and the variation coefficient is 0.15 or less. Section 9. Item 9. The organic piezoelectric film according to any one of items 1 to 8, having a tensile elastic modulus in the range of 0.4 to 5 GPa. Section 10. Item 10. The organic piezoelectric film according to any one of items 1 to 9, having a retardation in the range of 200 to 10,000 nm. Section 11. Item 10. The organic piezoelectric film according to any one of items 1 to 9, having a retardation in the range of 0.5 to 200 nm. Section 12. 12. The organic piezoelectric film according to any one of items 1 to 11, which is made of a polarized vinylidene fluoride polymer film. Section 13. 13. The organic piezoelectric film according to any one of items 1 to 12, having an internal haze value in the range of 0.05 to 80%. Section 14. 13. The organic piezoelectric film according to any one of items 1 to 12, having an internal haze value in the range of 5 to 90%. Section 15. A piezoelectric panel comprising the organic piezoelectric film according to any one of items 1 to 14 (preferably the organic piezoelectric film according to any one of items 1 to 13). Section 16. A pressure sensor comprising the organic piezoelectric film according to any one of items 1 to 14 (preferably the organic piezoelectric film according to any one of items 1 to 12 and 14). Section 17. Item 17. A haptic device having the organic piezoelectric film according to any one of items 1 to 14 (preferably, the organic piezoelectric film according to any one of items 1, 2, 5 to 12, and 14). A vibration power generating device comprising the organic piezoelectric film according to any one of items 1 to 14 (preferably the organic piezoelectric film according to any one of items 1, 2, 5 to 12, and 14). Section 19. A flat speaker having the organic piezoelectric film according to any one of items 1 to 14 (preferably, the organic piezoelectric film according to any one of items 1, 2, 5 to 12, and 14). Effect of the Invention

[0017] According to the present invention, there is provided an organic piezoelectric film having small in-plane variation in piezoelectricity. The organic piezoelectric film of the present invention is excellent in that it is less likely to malfunction when used in, for example, a touch panel capable of detecting touch pressure (particularly when used in a large-area touch panel capable of detecting touch pressure). Furthermore, the organic piezoelectric film of the present invention is excellent in that stable sensing can be achieved, for example, when used in a pressure sensor (especially when used in a large-area pressure sensor). Furthermore, the organic piezoelectric film of the present invention is excellent in that, for example, when used in a haptic device, operational errors and malfunctions of the device are unlikely to occur. Furthermore, the organic piezoelectric film of the present invention is advantageous in that, for example, when used in a vibration power generation device, a constant and stable amount of power can be generated. Furthermore, the organic piezoelectric film of the present invention is excellent in that, for example, when used in a flat speaker (particularly when used in a large-area flat speaker), high sound quality can be obtained. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing an overview of a production apparatus used in producing the organic piezoelectric film of Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] term Unless otherwise specified, symbols and abbreviations in this specification should be interpreted in the context of this specification as having the meanings commonly used in the technical field to which the present invention pertains. As used herein, the phrase "comprising" is intended to encompass the phrases "consisting essentially of" and "consisting of." In this specification, "detection" of "touch position" refers to determining the touch position, while "detection" of "touch pressure" refers to determining the presence or absence, speed, magnitude, or a combination thereof of pressure. As used herein, the term "touch" encompasses touching, being touched, pressing, being pressed, and contacting. As used herein, the term "polarized" means having an electric charge imparted to the surface, i.e., the polarized film can be an electret. In this specification, the term "haptic device" refers to a device that has the function of providing tactile feedback to a user. Unless otherwise specified, symbols and abbreviations in this specification should be interpreted in the context of this specification as having the meanings commonly used in the technical field to which the present invention pertains. As used herein, "variance" is the ratio of standard deviation / arithmetic mean.

[0020] Organic Piezoelectric Film The organic piezoelectric film of the present invention has a piezoelectric constant d 33 The organic piezoelectric film has a coefficient of variation of 2.0 or less. The organic piezoelectric film of the present invention will be described in detail below.

[0021] The organic piezoelectric film of the present invention is a film (polymer film) formed from an organic polymer. Examples of the "organic piezoelectric film" include a polarized vinylidene fluoride polymer film, an odd-chain nylon piezoelectric film, and polylactic acid. The "organic piezoelectric film" may contain components other than the polymer. The "organic piezoelectric film" includes a film made of the polymer and a film in which an inorganic substance is dispersed in the polymer. The content of the polymer in the organic piezoelectric film of the present invention (i.e., the polymer forming the organic piezoelectric film of the present invention) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass. The upper limit of the content is not particularly limited, and may be, for example, 100% by mass or 99% by mass. The polymer is preferably a vinylidene fluoride polymer. The organic piezoelectric film of the present invention preferably comprises a polarized vinylidene fluoride-based polymer film. In this specification, examples of the "vinylidene fluoride polymer film" include vinylidene fluoride / tetrafluoroethylene copolymer films, vinylidene fluoride / trifluoroethylene copolymer films, and polyvinylidene fluoride films. The vinylidene fluoride polymer film is preferably a vinylidene fluoride / tetrafluoroethylene copolymer film. The "vinylidene fluoride polymer film" may contain additives that are commonly used in resin films.

[0022] The "vinylidene fluoride polymer film" is a film composed of a vinylidene fluoride polymer and contains a vinylidene fluoride polymer.

[0023] Examples of the "vinylidene fluoride polymer" include: (1) A copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith; and (2) Polyvinylidene fluoride Examples include

[0024] Examples of the "monomer copolymerizable therewith" in the "(1) copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith" include trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, and vinyl fluoride. The "one or more monomers copolymerizable therewith" or one of them is preferably tetrafluoroethylene. A preferred example of the "vinylidene fluoride polymer" is a vinylidene fluoride / tetrafluoroethylene copolymer. The "vinylidene fluoride / tetrafluoroethylene copolymer" may contain repeating units derived from monomers other than vinylidene fluoride and tetrafluoroethylene, so long as the properties related to the present invention are not significantly impaired. The above-mentioned "(1) copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith" contains 50 mol % or more (preferably 60 mol % or more) of repeating units derived from vinylidene fluoride. The molar ratio of (repeating units derived from tetrafluoroethylene) / (repeating units derived from vinylidene fluoride) in the "vinylidene fluoride / tetrafluoroethylene copolymer" is preferably within the range of 5 / 95 to 36 / 64, more preferably within the range of 15 / 85 to 25 / 75, and even more preferably within the range of 18 / 82 to 22 / 78.

[0025] The "vinylidene fluoride / tetrafluoroethylene copolymer" may contain repeating units derived from monomers other than vinylidene fluoride and tetrafluoroethylene, so long as the properties related to the present invention are not significantly impaired. Usually, the content of such repeating units is 10 mol% or less. Such monomers are not limited as long as they are copolymerizable with vinylidene fluoride monomers and tetrafluoroethylene monomers, and examples thereof include: (1) Fluoromonomers (e.g., vinyl fluoride (VF), trifluoroethylene (TrFE), hexafluoropropene (HFP), 1-chloro-1-fluoro-ethylene (1,1-CFE), 1-chloro-2-fluoro-ethylene (1,2-CFE), 1-chloro-2,2-difluoroethylene (CDFE), chlorotrifluoroethylene (CTFE), trifluorovinyl monomers, 1,1,2-trifluorobutene-4-bromo-1-butene, 1,1,2-trifluorobutene-4-silane-1-butene, perfluoroalkyl vinyl ethers, perfluoromethyl vinyl ether (PMVE), perfluoropropyl vinyl ether (PPVE), perfluoroacrylates, 2,2,2-trifluoroethyl acrylate, 2-(perfluorohexyl)ethyl acrylate); and (2) Hydrocarbon monomers (e.g., ethylene, propylene, maleic anhydride, vinyl ether, vinyl ester, allyl glycidyl ether, acrylic acid monomers, methacrylic acid monomers, and vinyl acetate).

[0026] A suitable example of the "inorganic material" is inorganic oxide particles. By containing the "inorganic oxide particles", the highly dielectric film of the present invention can have a high dielectric constant. This can also significantly improve the volume resistivity while maintaining a high dielectric constant.

[0027] A suitable example of the "inorganic material" is inorganic oxide particles. By containing the "inorganic oxide particles", the organic piezoelectric film of the present invention can have a high dielectric constant. In addition, the volume resistivity can be significantly improved while maintaining a high dielectric constant. In addition, the electrical insulation can be improved.

[0028] The "inorganic oxide particles" are preferably at least one type selected from the group consisting of the following inorganic oxide particles (B1) to (B3).

[0029] [Inorganic oxide particles (B1)] Particles of inorganic oxides of metal elements of Groups 2, 3, 4, 12, or 13 of the periodic table, or composite particles of these inorganic oxides. Examples of the metal elements include Be, Mg, Ca, Sr, Ba, Y, Ti, Zr, Zn, and Al, etc. Among these, oxides of Al, Mg, Y, and Zn are preferred because they are versatile, inexpensive, and have high volume resistivity. Among these, specifically, particles of at least one metal oxide selected from the group consisting of Al2O3, MgO, ZrO2, Y2O3, BeO, and MgO.Al2O3 are preferred because they have high volume resistivity. Among these, Al2O3 having a γ-type crystal structure is preferred because it has a large specific surface area and good dispersibility in the above-mentioned "polymer" such as a vinylidene fluoride polymer, particularly in a vinylidene fluoride / tetrafluoroethylene copolymer.

[0030] [Inorganic oxide particles (B2)] Formula: M 1 a1 M 2 b1 O c1 (In the formula, M 1 Group 2 metal elements ;M 2 is a Group 4 metal element; a1 is 0.9 to 1.1; b1 is 0.9 to 1.1; c1 is 2.8 to 3.2; M 1 and M 2 Each of the elements may be one or more metal elements. As the "Group 4 metal element", for example, Ti and Zr are preferable. As the "Group 2 metal element", for example, Mg, Ca, Sr, and Ba are preferable. Among the "particles of inorganic composite oxides", specifically, particles of at least one type of inorganic oxide selected from the group consisting of BaTiO3, SrTiO3, CaTiO3, MgTiO3, BaZrO3, SrZrO3, CaZrO3, and MgZrO3 are preferred because they have high volume resistivity.

[0031] [Inorganic oxide particles (B3)] Composite inorganic oxide particles of oxides of metal elements of Groups 2, 3, 4, 12, or 13 of the periodic table, and silicon oxide. The "inorganic oxide particles (B3)" are composite particles of the "inorganic oxide" of the "inorganic oxide particles (B1)" and silicon oxide. Specific examples of the "inorganic oxide particles (B3)" include particles of at least one type of inorganic oxide selected from the group consisting of 3A12O3·2SiO2, 2MgO·SiO2, ZrO2·SiO2, and MgO·SiO2.

[0032] The "inorganic oxide particles" do not necessarily have to be highly dielectric and can be appropriately selected depending on the application of the organic piezoelectric film of the present invention. For example, the use of one type of versatile and inexpensive metal oxide particles (B1) (particularly Al2O3 particles and MgO particles) can improve the volume resistivity. The relative dielectric constant (1 kHz, 25°C) of these one type of metal oxide particles (B1) is usually less than 100, preferably 10 or less.

[0033] As the "inorganic oxide particles", ferroelectric inorganic oxide particles (e.g., inorganic oxide particles (B2) and (B3)) having a relative dielectric constant (dielectric constant (1 kHz, 25°C) of 100 or more) may be used for the purpose of improving the dielectric constant. Examples of inorganic materials constituting the ferroelectric inorganic oxide particles (B2) and (B3) include, but are not limited to, composite metal oxides, composites thereof, solid solutions, and sol-gel bodies.

[0034] The organic piezoelectric film of the present invention can contain the "inorganic oxide particles" in an amount of preferably 0.01 to 300 parts by mass, more preferably 0.1 to 100 parts by mass, per 100 parts by mass of the "polymer". If the content of the "inorganic oxide particles" is too high, it may be difficult to uniformly disperse the "inorganic oxide particles" in the "polymer", and the electrical insulation (voltage resistance) may decrease. If the content is 300 parts by mass or more, the film may become brittle and the tensile strength may decrease. From this viewpoint, the upper limit of the content is preferably 200 parts by mass, more preferably 150 parts by mass. If the content is too low, the effect of improving the electrical insulation is difficult to obtain. From this viewpoint, the lower limit of the content is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, and even more preferably 1 part by mass. On the other hand, when a high total light transmittance and a low total haze value are required for the organic piezoelectric film of the present invention, the content is preferably smaller, and further, when a particularly high total light transmittance and a low total haze value are required for the organic piezoelectric film of the present invention, the organic piezoelectric film of the present invention may preferably not contain the "inorganic oxide particles". Specific examples of cases where a high total light transmittance and a low total haze value are required for the organic piezoelectric film of the present invention include cases where the organic piezoelectric film of the present invention is used for a piezoelectric panel such as a touch panel.

[0035] The inorganic oxide particles preferably have a small average primary particle size, and more preferably have an average primary particle size of 1 μm or less, i.e., so-called nanoparticles. By uniformly dispersing such inorganic oxide nanoparticles, the electrical insulation of the film can be significantly improved with a small amount of incorporation. The average primary particle diameter is preferably 800 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less. There is no particular lower limit to the average primary particle diameter, but in view of the difficulty of production, the difficulty of uniform dispersion, and the cost, the average primary particle diameter is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 50 nm or more. Here, when a high total light transmittance and a low total haze value are required for the organic piezoelectric film of the present invention, the average primary particle diameter is preferably smaller. The average primary particle diameter of the "inorganic oxide particles" is calculated using a laser diffraction / scattering type particle size distribution analyzer LA-920 (product name) (Horiba, Ltd.) or an equivalent product.

[0036] The dielectric constant (25°C, 1 kHz) of the "inorganic oxide particles" is preferably 10 or more. From the viewpoint of increasing the dielectric constant of the piezoelectric film, the dielectric constant is preferably 100 or more, more preferably 300 or more. There is no particular upper limit to the dielectric constant, but it is usually about 3000. The dielectric constant (ε) (25°C, 1 kHz) of the "inorganic oxide particles" is a value calculated by measuring the capacitance (C) using an LCR meter and calculating the capacitance, electrode area (S), and thickness (d) of the sintered body according to the formula C = εε0 × S / d (ε0 dielectric constant in vacuum).

[0037] The organic piezoelectric film of the present invention may contain other components, such as an affinity improver, if necessary.

[0038] The "affinity improver" is contained in the organic piezoelectric film of the present invention when the organic piezoelectric film of the present invention contains the "inorganic oxide particles". The "affinity improver" can increase the affinity between the "inorganic oxide particles" and the "polymer", uniformly disperse the "inorganic oxide particles" in the "polymer", firmly bond the "inorganic oxide particles" and the "polymer" in the film, suppress the generation of voids, and increase the relative dielectric constant.

[0039] As the "affinity improver", a coupling agent, a surfactant, or an epoxy group-containing compound is effective.

[0040] Examples of the "coupling agent" include organotitanium compounds, organosilane compounds, organozirconium compounds, organoaluminum compounds, and organophosphorus compounds.

[0041] Examples of the "organic titanium compound" include coupling agents such as alkoxytitanium, titanium chelate, and titanium acylate. Among them, preferred examples include alkoxytitanium and titanium chelate because of their good affinity with the "inorganic oxide particles".

[0042] Specific examples include tetraisopropyl titanate, titanium isopropoxyoctylene glycolate, diisopropoxy bis(acetylacetonato)titanium, diisopropoxy titanium diisostearate, tetraisopropyl bis(dioctylphosphite)titanate, and isopropyl tri(n-aminoethyl-aminoethyl)titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(di-tridecyl)phosphite titanate.

[0043] The "organosilane compound" may be a polymer or a low molecular weight compound, and examples thereof include alkoxysilanes such as monoalkoxysilane, dialkoxysilane, trialkoxysilane, and tetraalkoxysilane. In addition, vinylsilane, epoxysilane, aminosilane, metachloroxysilane, mercaptosilane, and the like may also be suitably used.

[0044] When an alkoxysilane is used, hydrolysis can be used to achieve a further improvement in volume resistivity (improvement in electrical insulation), which is an effect of the surface treatment.

[0045] Examples of the "organozirconium compound" include alkoxyzirconium and zirconium chelates.

[0046] Examples of the "organoaluminum compound" include alkoxyaluminum and aluminum chelate.

[0047] Examples of the "organophosphorus compounds" include phosphites, phosphates, and phosphate chelates.

[0048] The "surfactant" as the affinity improver may be a polymer type or a low molecular type, and examples thereof include nonionic surfactants, anionic surfactants, and cationic surfactants. Among them, polymer type surfactants are preferred because of their good thermal stability.

[0049] Examples of the "nonionic surfactant" include polyether derivatives, polyvinylpyrrolidone derivatives, and alcohol derivatives. Among these, polyether derivatives are preferred because of their good affinity with the "inorganic oxide particles."

[0050] Examples of the "anionic surfactant" include polymers containing sulfonic acid, carboxylic acid, and salts thereof. Among them, preferred examples include acrylic acid derivative polymers and methacrylic acid derivative polymers, which have good affinity with the "polymer".

[0051] Examples of the "cationic surfactant" include amine compounds, compounds having a nitrogen-containing composite ring such as imidazoline, and halogenated salts thereof.

[0052] The "epoxy group-containing compound" as the "affinity improver" may be a low molecular weight compound or a high molecular weight compound, and examples thereof include epoxy compounds and glycidyl compounds. Among them, a low molecular weight compound having one epoxy group is preferred because of its particularly good affinity with the "polymer".

[0053] A preferred example of the "epoxy group-containing compound" is a compound represented by the formula:

[0054] [ka]

[0055] (In the formula, R represents a hydrogen atom, a methyl group, a hydrocarbon group having 2 to 10 carbon atoms which may have an oxygen atom or a nitrogen atom interposed therebetween, or an aromatic ring group which may be substituted; l represents 0 or 1; m represents 0 or 1; and n represents an integer of 0 to 10.)

[0056] Examples of this include: [ka] Examples of compounds having a ketone group or an ester group include:

[0057] The "affinity improver" can be used in an amount within a range in which the effects of the present invention are not lost. Specifically, in terms of uniform dispersion and high relative dielectric constant of the obtained film, the amount is preferably within a range of 0.01 to 30 parts by mass, more preferably within a range of 0.1 to 25 parts by mass, and even more preferably within a range of 1 to 20 parts by mass, relative to 100 parts by mass of the "inorganic oxide particles."

[0058] Furthermore, the organic piezoelectric film of the present invention may contain additives other than those mentioned above, as long as the effect of the present invention is not lost.

[0059] In this specification, the "piezoelectric constant d 33 " is a value determined according to the following measurement method.

[0060] Piezoelectric constant and its variation coefficient

[0061] <Piezoelectric constant d 33 How to determine Piezoelectric constant d 33The measurement is carried out using a piezometer system PM300 by PIEZOTEST (a pin with a tip of 1.5 mm diameter is attached as a sample fixing jig) or an equivalent. Here, the piezoelectric constant d 33 The arithmetic mean value of the piezoelectric constant d 33 In the present invention, on the film The selection of 10 points without arbitrariness can be done, for example, by selecting 10 points at 50 mm intervals on a straight line. Here, arbitrariness means that the coefficient of variation, which will be described later, is intended to be small. Piezoelectric constant d 33 The measured value of the piezoelectric constant d 33 The absolute value is stated as the value of

[0062] The piezoelectric constant d of the organic piezoelectric film 33 The coefficient of variation of the piezoelectric constant d 33 " is the ratio of the standard deviation to the arithmetic mean.

[0063] The piezoelectric constant d of the organic piezoelectric film of the present invention 33 The coefficient of variation is less than or equal to 2.0. As a result, the organic piezoelectric film of the present invention has small in-plane variation in piezoelectricity, and specifically, as a result, for example, the following advantages are obtained. The organic piezoelectric film of the present invention is unlikely to malfunction, for example, when used in a touch panel capable of detecting touch pressure (particularly when used in a large-area touch panel capable of detecting touch pressure). Furthermore, when the organic piezoelectric film of the present invention is used in, for example, a pressure sensor (especially when used in a large-area pressure sensor), stable sensing can be achieved. Furthermore, when the organic piezoelectric film of the present invention is used in, for example, a haptic device, operational errors and malfunctions of the device are unlikely to occur. Furthermore, when the organic piezoelectric film of the present invention is used in, for example, a vibration power generation device, a constant and stable amount of power generation can be obtained. Furthermore, the organic piezoelectric film of the present invention is excellent in that, for example, when used in a flat speaker (particularly when used in a large-area flat speaker), high sound quality can be obtained.

[0064] The piezoelectric constant d of the organic piezoelectric film of the present invention 33 From this viewpoint, it is preferable that the coefficient of variation is smaller, and therefore, the upper limit of the coefficient of variation is preferably 1.0, more preferably 0.6, even more preferably 0.4, still more preferably 0.3, and particularly preferably 0.15.

[0065] On the other hand, in some applications or usage modes of the organic piezoelectric film of the present invention, it may not be necessary for the coefficient of variation to be very small. In such cases, a larger coefficient of variation may be advantageous in terms of production costs, etc. Therefore, the piezoelectric constant d of the organic piezoelectric film of the present invention 33 The lower limit of the coefficient of variation can be, for example, 0.0001, 0.001, 0.01, or 0.02.

[0066] Piezoelectric constant d of organic piezoelectric film 33 The coefficient of variation of can be, for example, in the range of 0.01 to 1.0, in the range of 0.01 to 0.6, in the range of 0.01 to 0.5, in the range of 0.01 to 0.4, or in the range of 0.01 to 0.3.

[0067] Preferred piezoelectric constant d of the organic piezoelectric film of the present invention 33 may vary depending on the purpose or mode of use. Preferred piezoelectric constant d of the organic piezoelectric film of the present invention 33 The upper limit can be, for example, 30 pC / N, 28 pC / N, 26 pC / N, or 20 pC / N. Preferred piezoelectric constant d of the organic piezoelectric film of the present invention 33 The lower limit can be, for example, 0.5 pC / N, 3 pC / N, 5 pC / N, 7 pC / N, or 9 pC / N. Piezoelectric constant d of organic piezoelectric film 33can be in the range of 0.5 to 30 pC / N, in the range of 0.5 to 28 pC / N, in the range of 0.5 to 26 pC / N, in the range of 0.5 to 20 pC / N, in the range of 3 to 30 pC / N, in the range of 5 to 30 pC / N, in the range of 7 to 30 pC / N, or in the range of 9 to 30 pC / N.

[0068] The organic piezoelectric film according to a preferred embodiment of the present invention (the embodiment of the above item 3) has a piezoelectric constant d 33 The piezoelectric constant d of the organic piezoelectric film of this embodiment is in the range of 0.5 to less than 2.0 pC / N. 33 The coefficient of variation of is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.5 or less. The organic piezoelectric film of this embodiment can be suitably used for, for example, a piezoelectric panel or a pressure sensor.

[0069] In another preferred embodiment of the present invention (the embodiment of item 4), the organic piezoelectric film has a piezoelectric constant d 33 is within the range of 2.0 to less than 4.0 pC / N, and the coefficient of variation is 1.0 or less (preferably 0.8 or less, more preferably 0.5 or less, and even more preferably 0.3 or less). The organic piezoelectric film of this embodiment can be suitably used for, for example, a piezoelectric panel or a pressure sensor.

[0070] In another preferred embodiment of the present invention (the embodiment of item 5), the organic piezoelectric film has a piezoelectric constant d 33 is within the range of 4.0 to less than 6.0 pC / N, and the coefficient of variation is 0.6 or less (preferably 0.5 or less, more preferably 0.4 or less, and even more preferably 0.3 or less). The organic piezoelectric film of this embodiment can be suitably used for, for example, a piezoelectric panel, a pressure sensor, a haptic device, a piezoelectric vibration power generation device, or a flat speaker.

[0071] In another preferred embodiment of the present invention (the embodiment of item 6), the organic piezoelectric film has a piezoelectric constant d 33is within the range of 6.0 to less than 10.0 pC / N, and the coefficient of variation is 0.4 or less (preferably 0.3 or less, more preferably 0.25 or less, and even more preferably 0.2 or less). The organic piezoelectric film of this embodiment can be suitably used for, for example, a piezoelectric panel, a pressure sensor, a haptic device, a piezoelectric vibration power generation device, or a flat speaker.

[0072] In another preferred embodiment of the present invention (the embodiment of item 7), the organic piezoelectric film has a piezoelectric constant d 33 is within the range of 10.0 to less than 14.0 pC / N, and the coefficient of variation is 0.3 or less (preferably 0.25 or less, more preferably 0.2 or less, and even more preferably 0.15 or less). The organic piezoelectric film of this embodiment can be suitably used for, for example, a piezoelectric panel, a pressure sensor, a haptic device, a piezoelectric vibration power generation device, or a flat speaker.

[0073] In another preferred embodiment of the present invention (the embodiment of item 8), the organic piezoelectric film has a piezoelectric constant d 33 is in the range of 14.0 to 30.0 pC / N, and the coefficient of variation is 0.15 or less (preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.07 or less). The organic piezoelectric film of this embodiment can be suitably used for, for example, a piezoelectric panel, a pressure sensor, a haptic device, a piezoelectric vibration power generation device, or a flat speaker.

[0074] Total light transmittance

[0075] <How to determine total light transmittance> In this specification, the "total light transmittance" is obtained by a light transmittance test based on JIS K-7361 using a haze meter NDH-7000 SP (product name, Nippon Denshoku Industries Co., Ltd.) or an equivalent product.

[0076] The preferred total light transmittance of the organic piezoelectric film of the present invention may vary depending on the application or mode of use. In applications or usage modes requiring high transparency, a higher total light transmittance is required. On the other hand, in applications or usage modes not requiring high total light transmittance, an organic piezoelectric film having a relatively low total light transmittance may be advantageous in terms of production costs. The upper limit of the total light transmittance of the organic piezoelectric film of the present invention is, for example, 97%, 96%, or 9 It could be 4%. The lower limit of the total light transmittance of the organic piezoelectric film of the present invention can be, for example, 70%, 80%, or 90%. The total light transmittance of the organic piezoelectric film of the present invention can be, for example, in the range of 70 to 97%, in the range of 80 to 96%, or in the range of 80 to 94%.

[0077] Haze Value

[0078] <How to determine haze value> In this specification, the "total haze value" is a value measured by a haze meter in accordance with JIS K-7136. Haze (NHD-7000 SP) or equivalent product This is obtained by a turbidity test. In this specification, the term "inner haze" refers to the total haze value measured by filling a glass cell with water, inserting a film therein, and measuring the haze value. In this specification, "outer haze" is calculated by subtracting the internal haze from the total haze of the film.

[0079] The preferred total haze value of the organic piezoelectric film of the present invention may vary depending on the application or mode of use. In applications or usage modes requiring high transparency, a lower haze value is required. On the other hand, in applications or usage modes not requiring a low total haze value, an organic piezoelectric film having a relatively high total haze value may be advantageous in terms of production costs. The upper limit of the total haze value of the organic piezoelectric film of the present invention can be, for example, 90%, 80%, 70%, or 60%. The lower limit of the total haze value of the organic piezoelectric film of the present invention can be, for example, 0.3%, 0.4%, 0.5%, 5%, 20%, or 40%. The total haze value of the organic piezoelectric film of the present invention can be, for example, in the range of 0.3 to 80%, in the range of 0.4 to 70%, in the range of 0.5 to 70%, in the range of 0.5 to 60%, or in the range of 0.5 to 50%.

[0080] The preferred internal haze value of the organic piezoelectric film of the present invention may vary depending on the application or mode of use. In applications or usage modes requiring high transparency, a lower internal haze value is required. On the other hand, in applications or usage modes not requiring a low total haze value, an organic piezoelectric film having a relatively high internal haze value may be advantageous in terms of production costs. The upper limit of the internal haze value of the organic piezoelectric film of the present invention can be, for example, 90%, 80%, 70%, 60%, 50%, or 40%. The lower limit of the internal haze value of the organic piezoelectric film of the present invention can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 5%, 10%, or 20%. The internal haze value of the organic piezoelectric film of the present invention can be, for example, in the range of 0.05 to 80%, in the range of 0.1 to 70%, or in the range of 0.15 to 60%, in the range of 5 to 90%, in the range of 10 to 80%, or in the range of 20 to 70%.

[0081] The preferred external haze value of the organic piezoelectric film of the present invention may vary depending on the application or mode of use. In applications or usage modes requiring high transparency, a lower external haze value is required. On the other hand, in applications or usage modes not requiring a low total haze value, an organic piezoelectric film having a relatively high external haze value may be advantageous in terms of manufacturing costs. do. Since the external haze value is calculated by subtracting the internal haze value from the total haze value of the film, examples of the external haze value of the organic piezoelectric film of the present invention can be understood from the above examples of the total haze value and the above examples of the internal haze.

[0082] Thickness

[0083] <How to determine thickness> In this specification, the thickness of a film is defined as the arithmetic mean value of thicknesses measured at 10 arbitrarily selected points on the film.

[0084] The lower limit of the thickness of the organic piezoelectric film of the present invention can be, for example, 0.1 μm, 0.5 μm, 0.8 μm, 1 μm, 3 μm, 6 μm, 9 μm, or 10 μm. The upper limit of the thickness of the organic piezoelectric film of the present invention can be, for example, 200 μm, 100 μm, 50 μm, 40 μm, or 30 μm. The thickness of the organic piezoelectric film of the present invention is, for example, within a range of 0.1 to 200 μm, within a range of 1 to 100 μm, within a range of 0.5 to 100 μm, within a range of 0.8 to 50 μm, within a range of 0.8 to 40 μm, within a range of 3 to 100 μm, within a range of 3 to 50 μm, within a range of 6 to 50 μm, within a range of 9 to 40 μm, within a range of 10 to 50 μm, within a range of 10 to 40 μm, or within a range of 10 to 50 μm. The preferred thickness may vary depending on the application of the organic piezoelectric film of the present invention.

[0085] The organic piezoelectric film of the present invention can be a stretched or unstretched piezoelectric film. The organic piezoelectric film of the present invention is preferably a non-stretched piezoelectric film. In relation to this, the organic piezoelectric film of the present invention has high uniformity in thickness. Specifically, it is preferable that the organic piezoelectric film of the present invention has a coefficient of variation in thickness of 10% or less. Here, the coefficient of variation in thickness is the ratio of the standard deviation to the arithmetic mean of the film thickness, which is the arithmetic mean value. In addition, in this regard, the organic piezoelectric film of the present invention has high uniformity of shape and visual uniformity (i.e., less wrinkling and sagging (curvature in the absence of tension other than that due to gravity)). In relation to this, the organic piezoelectric film of the present invention has a high degree of uniformity in polarizability.

[0086] The organic piezoelectric film of the present invention is preferably a non-stretched piezoelectric film. In relation to this, the organic piezoelectric film of the present invention has a high uniformity in thickness. Specifically, the organic piezoelectric film of the present invention preferably has a coefficient of variation in thickness of 10% or less. Here, the thickness is measured at 5 mm intervals (i.e., at the lattice points of a 5 mm×5 mm square lattice) over the entire plane of the film, and the arithmetic average value is taken as the thickness of the organic piezoelectric film of the present invention. The coefficient of variation in thickness of the organic piezoelectric film is the ratio of the standard deviation to the arithmetic average of the thickness. In addition, in this regard, the organic piezoelectric film of the present invention has high uniformity of shape and visual uniformity (i.e., less wrinkling and sagging (curvature in the absence of tension other than that due to gravity)). In relation to this, the organic piezoelectric film of the present invention has a high degree of uniformity in polarizability.

[0087] Tensile modulus of elasticity

[0088] <How to determine the tensile modulus of elasticity> In this specification, the tensile modulus of elasticity is measured by cutting a film sample into a size of 20 mm wide x 100 mm long. Using an autograph (Shimadzu Corporation), the chuck distance was 50 mm and the speed was 50 mm / min. It is determined by measuring according to IS K7127.

[0089] The lower limit of the tensile elastic modulus of the organic piezoelectric film of the present invention can be, for example, 0.4 GPa, 0.5 GPa, or 0.6%. The upper limit of the tensile elastic modulus of the organic piezoelectric film of the present invention can be, for example, 5 GPa, 4 GPa, or 3 GPa. The tensile elastic modulus of the organic piezoelectric film of the present invention can be, for example, in the range of 0.5 to 10,000 nm, in the range of 0.5 to 7,000 nm, or in the range of 0.5 to 4,000 nm.

[0090] Retardation

[0091] <How to determine retardation> In this specification, the retardation is determined by cutting a film sample into a size of 2cm x 2cm or more and measuring it using a retardation film / optical material inspection device RETS-100 (product name, Otsuka Electronics) or an equivalent product. In this specification, the retardation value is the value at 550nm.

[0092] The lower limit of the retardation of the organic piezoelectric film of the present invention is not particularly limited, but can be, for example, 0.5 nm. The upper limit of the retardation of the organic piezoelectric film of the present invention can be, for example, 10000 nm, 7000 nm, or 4000 nm. The retardation of the organic piezoelectric film of the present invention may be preferably within the range of 0.5 to 10,000 nm, more preferably within the range of 0.5 to 7,000 nm, and even more preferably within the range of 0.5 to 4,000 nm. The organic piezoelectric film in a preferred embodiment of the present invention is a stretched film, and has a retardation in the range of 200 to 10,000 nm. The organic piezoelectric film in another preferred embodiment of the present invention is a non-stretched film, and has a retardation in the range of 0.5 to 200 nm.

[0093] Manufacturing method The organic piezoelectric film of the present invention may be, for example, Step A is to prepare a non-stretched and non-polarized polymer film (e.g., a non-polarized vinylidene fluoride polymer film) by a casting method; A step B of subjecting the unstretched and unpolarized polymer film to a polarization treatment; and A step C of heat-treating the unstretched polymer film at any time relative to the step B. Includes Manufacturing method It can be manufactured by

[0094] Process A (film preparation process)

[0095] The method for producing "the non-stretched and non-polarized film" by the casting method includes, for example, (1) a step of dissolving or dispersing the polymer (i.e., the polymer that forms the organic piezoelectric film of the present invention) (e.g., a vinylidene fluoride-based polymer) and the optional components (e.g., inorganic oxide particles and an affinity improver) in a solvent to dissolve the liquid composition, thereby preparing a liquid composition; (2) casting (applying) the liquid composition onto a substrate; and (3) A step of evaporating the solvent by heating and drying to form a film. The manufacturing method includes:

[0096] The dissolution temperature in the preparation of the liquid composition is not particularly limited, but a higher dissolution temperature is preferable because it can promote dissolution. However, if the dissolution temperature is too high, the resulting film tends to be colored, so the dissolution temperature is preferably from room temperature to 80° C. In order to prevent such coloration, preferred examples of the solvent include ketone-based solvents (e.g., methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), acetone, diethyl ketone, dipropyl ketone, cyclohexanone), ester-based solvents (e.g., ethyl acetate, methyl acetate, propyl acetate, butyl acetate, ethyl lactate), ether-based solvents (e.g., tetrahydrofuran, methyltetrahydrofuran, dioxane), and amide-based solvents (e.g., dimethylformamide (DMF), dimethylacetamide). These solvents may be used alone or in combination of two or more. As the solvent, an amide-based solvent, which is a solvent commonly used to dissolve polyvinylidene fluoride (PVDF), may be used, but the content of the amide-based solvent in the solvent is desirably 50% by weight or less.

[0097] The liquid composition may be cast (applied) onto a substrate by a conventional method such as knife coating, cast coating, roll coating, gravure coating, blade coating, rod coating, air doctor coating, or slot die. Among these, the gravure coating or slot die method is preferred because of ease of operation, small variation in the thickness of the resulting film, and excellent productivity. For example, a polyethylene terephthalate (PET) film can be used as the substrate.

[0098] The evaporation of the solvent by heat drying may be carried out in accordance with a heat drying method for forming a normal film. The heat drying may be preferably carried out, for example, by passing the liquid composition applied on the substrate through a drying oven in a roll-to-roll manner. Alternatively, the film may be formed by heat drying in a batch manner. The drying temperature varies depending on the type of polymer constituting the organic piezoelectric film of the present invention. Specifically, for example, when the polymer is a vinylidene fluoride / tetrafluoroethylene copolymer, the drying temperature is preferably within the range of 20°C to 200°C, more preferably within the range of 60°C to 190°C, and even more preferably within the range of 80°C to 190°C.

[0099] The thickness of the non-polarized film prepared in step A may be set depending on the piezoelectric film to be obtained.

[0100] Process B (polarization process) In step B, the non-polarized film is subjected to a polarization treatment.

[0101] The non-polarized copolymer film (hereinafter, sometimes simply referred to as "non-polarized film") used in step B is preferably not stretched. Also, in the method for producing an organic piezoelectric film of the present invention, the non-polarized film is preferably not stretched. The organic piezoelectric film thus obtained has high piezoelectricity even after exposure to high temperatures, and also has a small variation in thickness.

[0102] The polarization treatment in step B can be carried out by a conventional method such as a corona discharge treatment.

[0103] The polarization treatment in step B is preferably carried out by corona discharge. Either negative or positive corona may be used for the corona discharge, but it is preferable to use negative corona from the viewpoint of ease of polarization of the non-polarized resin film.

[0104] The corona discharge treatment is not particularly limited, but can be performed, for example, by applying a voltage to a non-polarized film using a linear electrode as described in JP 2011-181748 A; applying a voltage to a non-polarized film using a needle electrode; or applying a voltage to a non-polarized film using a grid electrode. The conditions of the corona discharge treatment may be appropriately set based on common knowledge in the technical field to which the present invention pertains. If the conditions of the corona discharge treatment are too weak, the piezoelectricity of the resulting piezoelectric film may be insufficient, whereas if the conditions of the corona discharge treatment are too strong, the resulting piezoelectric film may have point defects. Here, the piezoelectric constant d of the resulting polarized film is 33 In order to suppress the in-plane variation, it is desirable that the distance between each needle-shaped electrode and / or linear electrode and the film is constant, i.e., that there is no (or extremely small) in-plane variation in the distance between the electrodes and the film (specifically, the difference between the longest distance and the shortest distance is preferably within 6 mm, more preferably 4 mm, and even more preferably 3 mm or less). The piezoelectric constant d of the resulting polarized film is 33 In order to suppress the in-plane variation of the film, for example, when applying the film continuously by roll-to-roll, it is desirable to apply a certain tension to the film and to bring the film into moderate and uniform contact with the roll. For example, when continuous application is performed in a roll-to-roll manner using linear electrodes, the DC electric field is, for example, -15 to -25 kV, although it varies depending on the distance between the linear electrodes and the non-polarized film, the film thickness, etc. The treatment speed is, for example, 10 to 500 cm / min. Alternatively, the polarization treatment may be performed by, for example, sandwiching the non-polarized film between flat electrodes and applying a voltage to the film, in addition to corona discharge. Specifically, when applying a voltage to the non-polarized film by sandwiching the film between flat electrodes, a DC electric field of 0 to 400 MV / m (preferably 50 to 400 MV / m) and an application time of 0.1 seconds to 60 minutes can be used.

[0105] Process C (heat treatment process) Step C is carried out at any time relative to step B. That is, step C can be carried out before, simultaneously with, or after step B. When step C is carried out after step B, the heat treatment in step C can be carried out on the polarized film obtained in step B or on the portion where polarization has been completed in step B. That is, while the polarization treatment in step B is being carried out, the heat treatment in step C may be carried out on the portion where polarization treatment has been completed. The heat treatment method is not particularly limited, but may be, for example, by sandwiching the non-stretched polymer film (hereinafter, sometimes simply referred to as the film) between two metal plates and heating the metal plates; heating a roll of the film in a thermostatic chamber; or, in the production of the film by a roll-to-roll method, by heating a metal roll and bringing the film into contact with the heated metal roll; or by passing the film through a heated furnace in a roll-to-roll manner. Here, when step C is performed after step B, the polarized film may be heat-treated alone, or may be laminated on another film or metal foil to create a laminated film, which may then be heat-treated. In particular, when heat-treating at high temperatures, the latter method is preferable because it is less likely to cause wrinkles in the polarized film. The temperature of the heat treatment may vary depending on the type of polarized film to be heat treated, but 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. Specifically, the temperature of the heat treatment is preferably 80° C. or higher, more preferably 85° C. or higher, and even more preferably 90° C. or higher. The temperature of the heat treatment is preferably 170° C. or less, more preferably 160° C. or less, and even more preferably 140° C. or less. The time for the heat treatment is usually 10 seconds or more, preferably 0.5 minutes or more, more preferably 1 minute or more, and further preferably 2 minutes or more. Further, there is no upper limit to the time for the heat treatment, but the time for the heat treatment is usually 60 minutes or less. The heat treatment is preferably performed at 90° C. or higher for 1 minute or longer.

[0106] After the heat treatment, the film is cooled to a predetermined temperature. The temperature is preferably in the range of 0°C to 60°C, and may be room temperature. The cooling rate may be slow or rapid, and rapid cooling is preferred from the viewpoint of productivity. Rapid cooling may be performed by means of, for example, blowing air. In this specification, such heat treatment of the film may be referred to as annealing treatment.

[0107] Roll of organic piezoelectric film The organic piezoelectric films of the present invention may preferably be stored and shipped as rolls. From the viewpoint of preventing wrinkles from occurring when the organic piezoelectric film of the present invention is formed into such a roll, the elastic modulus is preferably 500 MPa or more. The elastic modulus can be adjusted by selecting the material of the film, etc. The roll of the organic piezoelectric film of the present invention may consist only of the organic piezoelectric film of the present invention, or may be in a form in which the organic piezoelectric film of the present invention is laminated with a protective film or the like and wound up, or may include a core such as a paper tube, and the organic piezoelectric film of the present invention wound around the core. A roll of the organic piezoelectric film of the present invention preferably has a width of 50 mm or more and a length of 20 m or more. A roll of the organic piezoelectric film of the present invention can be prepared, for example, by winding the organic piezoelectric film of the present invention around an unwind roller and a take-up roller. Here, from the viewpoint of suppressing deflection of the film, it is preferable to make the unwinding roller and the take-up roller parallel to each other, as is usually done. From the viewpoint of suppressing deflection of the film, among the organic piezoelectric films of the present invention, a film having an elastic modulus of 500 MPa or more may be used. As the roller, in order to improve the slipperiness of the film of the present invention, it is preferable to use a roller with good slipperiness, specifically a roller covered with a fluororesin, a plated roller, or a roller coated with a release agent. Here, if the thickness of the film is not uniform, unevenness in the thickness of the roll such as so-called roll edge (high edge; thicker ends compared to the center in the axial direction of the roll; when the film thickness at both ends is thinner than at the center, both ends are recessed compared to the center; or when the thickness changes gradually from one end to the other end, the end with the thinner film is recessed) occurs, which can cause wrinkles. This can also cause the film to sag when unwound (curving when no tension other than that due to gravity is applied). In general, in order to prevent the formation of raised edges on a roll, the ends of the film that form the ends of the roll are slit using a slitter, but if the unevenness in the film thickness extends over a wide area from the end of the film, it is difficult to prevent raised edges and dents on the roll by slitting alone. Generally, the wider the film (eg, 100 mm or more) and the longer the film (eg, 50 m or more), the more likely the raised edges, dents and warping will occur. However, since the organic piezoelectric film of the present invention has a high degree of thickness uniformity, it is possible to form a roll in which the above-mentioned edge projections, dents, and deflection are suppressed, even when the film is wide (e.g., 100 mm or more) and long (e.g., 50 m or more), either as is or by simply slittering (slitting) the film ends that will become the ends of the roll. The edges (film ends) removed by the slits can be collected and recycled as the raw material for the organic piezoelectric film of the present invention. The roll of the organic piezoelectric film of the present invention has a high uniformity in thickness, and preferably, the ratio of the thickness of the thicker end of the roll to the thickness of the central portion in the axial direction of the roll is within a range of 70 to 130%. It is. As a result, the deflection of the film when unwound from the roll of the organic piezoelectric film of the present invention is suppressed.

[0108] The surface roughness Ra of the roller used in the production of the organic piezoelectric film of the present invention and the roll thereof is preferably 1 μm or less. This is the "arithmetic mean height" as defined in B0601:2001. Furthermore, it is preferable that at least the surface of the roller used in producing the organic piezoelectric film and roll thereof of the present invention is made of polytetrafluoroethylene (PTFE), chrome plating, or stainless steel (SUS). These factors can suppress wrinkling of the film.

[0109] Applicable The organic piezoelectric film of the present invention has high piezoelectricity even after exposure to high temperatures, and therefore can be suitably used in various applications requiring high piezoelectricity and in which there is a possibility of exposure to high temperatures. Furthermore, the organic piezoelectric film of the present invention has flexibility and can be suitably used for various applications.

[0110] Piezoelectric Panel The organic piezoelectric film of the present invention (preferably the organic piezoelectric film according to any one of the embodiments described in items 1 to 13 above) can be used in piezoelectric panels (for example, touch panels capable of detecting touch pressure) and the like. A touch panel having the organic piezoelectric film of the present invention can detect both a touch position and a touch pressure, and the touch pressure detection performance is not easily deteriorated even after exposure to high temperatures. The organic piezoelectric film of the present invention can be used in touch panels of any type, such as resistive type and capacitive type. When used in a touch panel, the organic piezoelectric film of the present invention does not necessarily have to be used for detecting both the touch position and the touch pressure, and the organic piezoelectric film of the present invention may be used for detecting either the touch position or the touch pressure. The piezoelectric panel having the organic piezoelectric film of the present invention preferably has A first electrode; The organic piezoelectric film of the present invention; a second electrode); in this order. The first electrode is disposed directly or indirectly on one main surface of the organic piezoelectric film of the present invention; and A second electrode is disposed directly or indirectly on the other main surface of the organic piezoelectric film of the present invention. Here, the number of organic piezoelectric films that the piezoelectric panel has can be one or more. Here, in order to remove pyroelectric noise from the piezoelectric panel, the two organic piezoelectric films may form a bimorph structure (for example, a bimorph structure as shown in FIG. 18 of WO 2015 / 053343). At this time, the two organic piezoelectric films may be bonded together with a transparent adhesive or transparent bonding agent. Here, the thickness of the transparent adhesive or transparent bonding agent layer is preferably thicker when its tensile modulus is greater than that of the organic piezoelectric film, and is preferably thinner when its tensile modulus is smaller. In addition, it is preferable that the thickness of the two organic piezoelectric films is thicker on the side to which pressure is applied. Examples of such electrodes include ITO (indium tin oxide) electrodes, tin oxide electrodes, metal nanowires, metal nanoparticles, and organic conductive resins.

[0111] Pressure Sensor The organic piezoelectric film of the present invention (preferably the organic piezoelectric film according to any one of the embodiments described in items 1 to 12 and 14 above) can be used for a pressure sensor. The pressure sensor having the organic piezoelectric film of the present invention preferably comprises: A first electrode; The organic piezoelectric film of the present invention; a second electrode); in this order. The first electrode is disposed directly or indirectly on one main surface of the organic piezoelectric film of the present invention; and A second electrode is disposed directly or indirectly on the other main surface of the organic piezoelectric film of the present invention. Examples of such electrodes include ITO (indium tin oxide) electrodes, tin oxide electrodes, metal nanowires, metal nanoparticles, and organic conductive resins.

[0112] Haptic Devices The organic piezoelectric film of the present invention (preferably the organic piezoelectric film according to any one of the embodiments described in items 1, 2, 5 to 12, and 14) can be suitably used in a haptic device. The haptic device having the organic piezoelectric film of the present invention preferably comprises: A first electrode, The organic piezoelectric film of the present invention, and Second electrode They are in this order. The first electrode is disposed directly or indirectly on one main surface of the organic piezoelectric film of the present invention; and A second electrode is disposed directly or indirectly on the other main surface of the organic piezoelectric film of the present invention. In the haptic device, the organic piezoelectric film of the present invention can convert electrical energy received via the first electrode and the second electrode into mechanical energy, which causes the organic piezoelectric film of the present invention to deform and vibrate, providing tactile feedback to the user.

[0113] Piezoelectric vibration power generation device The organic piezoelectric film of the present invention (preferably the organic piezoelectric film according to any one of the embodiments described in items 1, 2, 5 to 12, and 14) can be suitably used in a piezoelectric vibration power generator. The piezoelectric vibration power generation device having the organic piezoelectric film of the present invention is preferably Preferably, A first electrode, The organic piezoelectric film of the present invention, and Second electrode They are in this order. The first electrode is disposed directly or indirectly on one main surface of the organic piezoelectric film of the present invention; and A second electrode is disposed directly or indirectly on the other main surface of the organic piezoelectric film of the present invention. The organic piezoelectric film of the present invention can convert mechanical energy of vibration received by a piezoelectric vibration power generation device into electrical energy. The electrical energy is sent to a secondary battery or the like via the first electrode and the second electrode.

[0114] Planar speaker The organic piezoelectric film of the present invention can be suitably used in a flat speaker. The flat speaker having the organic piezoelectric film of the present invention preferably has: Preferably, A first electrode, The organic piezoelectric film of the present invention, and Second electrode They are in this order. In the flat speaker, the organic piezoelectric film of the present invention can convert electrical energy received via the first electrode and the second electrode into mechanical energy, which causes the organic piezoelectric film of the present invention to deform and vibrate, thereby generating sound.

[0115] A touch panel having the organic piezoelectric film of the present invention can be used in an input device (i.e., an input device having the organic piezoelectric film of the present invention). An input device having the touch panel can input based on touch position, touch pressure, or both. An input device having the touch panel can have a position detection unit and a pressure detection unit.

[0116] The input device can be used in electronic devices (e.g., mobile phones (e.g., smartphones), personal digital assistants (PDAs), tablet PCs, ATMs, automatic ticket vending machines, and car navigation systems). Electronic devices having the input device can be operated and actuated based on touch position, touch pressure, or both.

[0117] Bimorph type piezoelectric film When the organic piezoelectric film of the present invention is used in a pressure sensor or a haptic device, the organic piezoelectric film of the present invention may have a so-called bimorph structure in which two organic piezoelectric films are bonded together. That is, the present invention also provides the bimorph piezoelectric film. When such a bimorph piezoelectric film is used as a pressure sensor, it is preferable that the bimorph piezoelectric film has a bimorph structure in which two organic piezoelectric films are bonded together so that the polarization directions of the two organic piezoelectric films are opposite to each other, particularly from the viewpoint of removing pyroelectric noise. In this way, the surfaces on which charges of the same polarity are generated by a temperature rise are arranged on the outside, so that a part or all of the pyroelectric signals (pyroelectric noise) generated from each pyroelectric film can be offset. The bimorph piezoelectric film can usually have a rectangular (e.g., rectangular, square) or circular (e.g., elliptical, perfect circle) shape in a plan view. A detection electrode can be provided on each of both sides of the bimorph piezoelectric film (piezoelectric element) (i.e., two organic piezoelectric films of the present invention). The two organic piezoelectric films of the present invention may be attached to each other with an adhesive sheet or adhesive layer, may be in direct contact with each other, may be heat-sealed to each other, or may be heat-pressed to each other. The pressure-sensitive adhesive sheet is not particularly limited as long as it allows two organic piezoelectric films of the present invention to be bonded to each other, and may be composed of one or more layers. That is, when the pressure-sensitive adhesive sheet is composed of one layer, the pressure-sensitive adhesive sheet is composed of a pressure-sensitive adhesive layer, and when the pressure-sensitive adhesive sheet is composed of two or more layers, both outer layers are pressure-sensitive adhesive layers. When the pressure-sensitive adhesive sheet is composed of three or more layers, the pressure-sensitive adhesive sheet may have a base layer as an inner layer. The substrate layer in the pressure-sensitive adhesive sheet may be any transparent film, and is preferably, for example, a film of polyimide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyparaphenylene sulfide, or polyamideimide. The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet can be, for example, a layer containing an acrylic pressure-sensitive adhesive as the pressure-sensitive adhesive. The adhesive forming the adhesive layer can be, for example, an acrylic adhesive. EXAMPLES

[0118] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. isn't it.

[0119] In the examples and comparative examples described below, the following electrodes were used. <Electrodes used> (1) A needle-shaped electrode bar in which electrode needles (needle electrodes) (R = 0.06 mm; manufactured by Morita Needle Works) are arranged in a row at 10 mm intervals along the center line of a 20 mm wide (10 mm thick, 500 mm long) brass rod. (2) As in (1), a needle-shaped electrode rod was used, with electrode needles (R = 0.06 mm; manufactured by Morita Needle Works) arranged in a row at 15 mm intervals. (3) A wire electrode (500 mm long) made of gold-plated tungsten with a diameter of 0.1 mm

[0120] In the examples and comparative examples described later, the total light transmittance, total haze value, and piezoelectric constant d33 were measured by the following methods. <Total light transmittance> The haze was measured using a haze meter NDH-7000SP (product name, Nippon Denshoku Industries Co., Ltd.) according to the method described in JIS K-7361. <Total Haze Value> The haze was measured using a haze meter NDH-7000SP (product name, Nippon Denshoku Industries Co., Ltd.) according to the method described in JIS K-7136. <Internal haze value> Water was poured into a quartz cell, the film was inserted into it, and measurements were made using an NDH-7000SP (product name, Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K-7136. <Piezoelectric constant d33 measurement> Piezoelectric constant d 33The measurement was performed using a piezometer system PM300 manufactured by PIEZOTEST Co., Ltd. In the measurement, the sample was clipped with 1N, and the generated charge was read when a force of 0.25N and 110Hz was applied. <Tensile elastic modulus> The tensile modulus of elasticity was measured by cutting a film sample into a size of 20 mm wide x 100 mm long and The measurement was carried out using a graph (Shimadzu Corporation) under the conditions of a chuck distance of 50 mm and a speed of 50 mm / min, based on JIS K7127. <Retardation> The retardation is determined by cutting a film sample into a size of 2 cm x 2 cm or more and measuring it using a retardation film and optical material inspection device RETS-100 (product name, Otsuka Electronics). In this specification, the retardation value is the value at 550 nm. do.

[0121] Production Example 1 (Production of Non-Polarizing Film) A vinylidene fluoride / tetrafluoroethylene copolymer film (molar ratio 80:20) having a thickness of 40 μm was produced by the following production method. Dimethyl fluoride of vinylidene fluoride-tetrafluoroethylene copolymer (molar ratio 80:20) A solution of dichloromethane in diethyl ether (DMAc) or methyl ethyl ketone (MEK) was cast onto a polyethylene terephthalate (PET) substrate, and the solvent was evaporated at 180°C to form a 40 μm-thick film.

[0122] Example 1 In an ISO class 7 clean room (humidity 60%), as shown in the outline in Figure 1, a vinylidene fluoride / tetrafluoroethylene copolymer film 2 (hereinafter sometimes simply referred to as film 2) having a width of 550 mm, a length of 200 m, and each film thickness (20 to 40 μm) shown in Table 1 was placed on a grounded roller 1 (diameter 200 mm, width 800 mm) made of SUS, so as to move along the roller 1 at a wrap angle of 200°. A needle-shaped electrode was used as the first electrode E1, and the arrangement of the needle-shaped electrodes was aligned along the surface of the roller 1. The needle-like electrode (first electrode E1) was placed so that the tip of the needle-like electrode was perpendicular to the film 2 (i.e., in the radial direction of the roller 1) and 10 mm above the film 2. A first high-voltage power supply V1 was connected to the first electrode E1. Furthermore, a wire electrode (550 mm long) made of gold-plated tungsten and having a diameter of 0.1 mm was placed as the second electrode E2 at a position 100 mm and 150 mm away from the needle-like electrode (first electrode E1) in terms of the length of the film 2, respectively, so that the wire electrode was 20 mm above the film 2. A second high-voltage power supply V2 was connected to each of the second electrodes E2. A voltage of -10 kV was applied to the needle electrode (first electrode E1) and a voltage of -10 to -15 kV was applied to the linear electrode (second electrode E2), and then the film 2 was moved in the direction of the arrow in Figure 3 at a speed of 96 cm / min, passing under the corona discharge generated from the tip of the needle electrode (first electrode) and the linear electrode (second electrode) that followed it, and further contacting the film 2 with a grounded metal roll 3 (diameter 70 mm) to remove static electricity from the film 2. Then, a slitter was used to remove a width of 0.5 cm from each end of the film 2, and the resulting polarized film was wound up around a cylindrical core with a diameter of 6 inches while sandwiching a PET film between them. Here, the distance between the needle-like electrode (first electrode E1) and the film 2, and the distance between the linear electrode (second electrode E2) and the film 2 were both adjusted to be constant (the difference between the longest and shortest distances between the electrodes and the film was 0 mm), and eight samples (sample numbers 1 to 8) were manufactured. In addition, the following two samples (sample numbers 9 and 10) Unlike the above-mentioned samples 1 to 8, the distance between the needle-shaped electrode (first electrode E1) and the film 2 was adjusted to be constant, but on the other hand, adjusting the distance between the linear electrode (second electrode E2) and the film 2 to be constant was omitted, so that the linear electrode was fixed at an angle and its right end was fixed at a position 25 mm above the film 2 and its left end was fixed at a position 15 mm above the film 2 in the direction of travel of the film 2, and one sample (film thickness 40 μm) was manufactured (sample number 9). Unlike the above-mentioned sample numbers 1 to 8, the distance between the linear electrode (second electrode E2) and the film 2 was adjusted to be constant, but on the other hand, adjusting the distance between the needle-shaped electrode (first electrode E1) and the film 2 to be constant was omitted, so that the linear electrode was fixed at an angle and the right end was fixed at a position 20 mm above the film 2 and the left end was fixed at a position 10 mm above the film 2 in the direction of film travel, and one sample (film thickness 20 μm) was manufactured (sample number 10).

[0123] Test Example 1 For the measurement of piezoelectricity, a d33 meter PM300 (to which a pin with a tip of 1.5 mmφ was attached as a sample fixing jig) manufactured by Piezo Test was used. The meter was set under the following conditions: Rng / Mode: VLO / d33, Frequency: 110 Hz, and Dyn Force: 0.25 N. A 102 g weight was placed on the detection part, and after confirming that the St.F of the meter was 1.0 N, the tip of the sample fixing jig was attached to the measurement jig according to the following procedure. (1) The film was cut to a size of 50 mm [machine direction] / 500 mm [width direction] (2) Place the piezoelectric film on a flat and clean surface to avoid creases or wrinkles. Placed it. (3) Marks were made with a permanent marker at 10 locations at 50 mm intervals across the width. (4) Place the film on the detector, taking care not to wrinkle or crease it, and press the trigger clockwise. Turn the force head until St.F: 1.0 N, and then lower the force head until St.F: 1.0 N. Seconds later the value of d33 was read. The measurement results are shown in Table 1. [Table 1]

Claims

1. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ The organic piezoelectric film has a coefficient of variation of 0.33 or less.

2. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ 2. The organic piezoelectric film according to claim 1, wherein the resistivity is in the range of 0.5 to 30 pC / N.

3. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ The organic piezoelectric film according to claim 1, wherein the piezoelectric constant is in the range of 0.5 to less than 2.0 pC / N.

4. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ The organic piezoelectric film according to claim 1, wherein the piezoelectric constant is in the range of 2.0 to less than 4.0 pC / N.

5. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ The organic piezoelectric film according to claim 1, wherein the piezoelectric constant is in the range of 4.0 to less than 6.0 pC / N.

6. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ The organic piezoelectric film according to claim 1, wherein the piezoelectric constant is in the range of 6.0 to less than 10.0 pC / N.

7. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ is in the range of 10.0 to less than 14.0 pC / N, and the piezoelectric constant d ３３ 2. The organic piezoelectric film according to claim 1, wherein the coefficient of variation of is 0.3 or less.

8. Piezoelectric constant d in a size of 50 mm x 500 mm ３３ is in the range of 14.0 to 30.0 pC / N, and the piezoelectric constant d ３３ 2. The organic piezoelectric film according to claim 1, wherein the coefficient of variation of is 0.15 or less.

9. The organic piezoelectric film according to any one of claims 1 to 8, having a tensile elastic modulus in the range of 0.4 to 5 GPa.

10. The organic piezoelectric film according to any one of claims 1 to 9, wherein the retardation is in the range of 200 to 10,000 nm.

11. The organic piezoelectric film according to any one of claims 1 to 9, wherein the retardation is in the range of 0.5 to 200 nm.

12. The organic piezoelectric film according to any one of claims 1 to 11, which is made of a polarized vinylidene fluoride polymer film.

13. The organic piezoelectric film according to any one of claims 1 to 12, which is a non-stretched film.

14. The organic piezoelectric film according to any one of claims 1 to 13, wherein the internal haze value is within a range of 0.05 to 80%.

15. The organic piezoelectric film according to any one of claims 1 to 13, wherein the internal haze value is within a range of 5 to 90%.

16. The organic piezoelectric film according to any one of claims 1 to 15, which contains a vinylidene fluoride / tetrafluoroethylene copolymer.

17. A piezoelectric panel comprising the organic piezoelectric film according to any one of claims 1 to 16.

18. A pressure sensor comprising the organic piezoelectric film according to any one of claims 1 to 16.

19. A haptic device comprising the organic piezoelectric film according to any one of claims 1 to 16.

20. A vibration power generating device comprising the organic piezoelectric film according to any one of claims 1 to 16.

21. A flat speaker comprising the organic piezoelectric film according to any one of claims 1 to 16.

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