Fluorofluoride polymer film

Abstract

The objective is to provide a fluorine-containing polymer film. This objective can be achieved by a fluorine-containing polymer film having a thermal shrinkage rate of 0.4% or less after heating at 90°C for 1 hour and a dielectric constant of 3 to 50 at 25°C and 1000 Hz, or by a fluorine-containing polymer film having a degree of crystallinity of 50% or more and an elongation at break of 400% or more.

Description

Technology Field

[0001] The present disclosure relates to a fluorine-containing polymer film having a low thermal shrinkage rate, and a fluorine-containing polymer film having a high degree of crystallinity and a high elongation at break. Background Technology

[0002] A piezoelectric film is a film that possesses piezoelectricity (the property of converting applied force into voltage, or the property of converting applied voltage into force). Piezoelectric films are used in various applications that utilize piezoelectricity [e.g., sensors, actuators, touch panels, haptic devices (devices that provide tactile feedback to the user), vibration generators, speakers, microphones].

[0003] As a piezoelectric film, polyvinylidene fluoride (PVDF) film is typically used. In order to impart good piezoelectricity to the PVDF film, it is necessary to perform polarization treatment by uniaxially stretching the PVDF film (e.g., Patent Document 1). Prior art literature

[0004] Japanese Patent Publication No. 2008-171935 The problem to be solved

[0005] However, uniaxially stretched PVDF films have large in-plane variations in film thickness and piezoelectricity, and also have a high thermal shrinkage rate. Generally, when a film is used as a sensor, it is necessary to form electrodes on both the front and back surfaces of the film, so the precision of positioning is very important. Since the formation of electrodes often involves heating, misalignment of positioning is likely to occur in the above PVDF films, which have a high thermal shrinkage rate.

[0006] In addition, while it is desired for piezoelectric films to be flexibly deformable, the elongation at break tends to decrease as the degree of crystallization increases through stretching, making it difficult to achieve both properties simultaneously.

[0007] The present disclosure aims to provide a fluorine-containing polymer film having a low thermal shrinkage rate, and a fluorine-containing polymer film having a high degree of crystallinity and a high elongation at break. means of solving the problem

[0008] The present disclosure includes the following aspects.

[0009] Paragraph 1.

[0010] A fluorine-containing polymer film having a thermal shrinkage rate of 0.4% or less after heating at 90°C for 1 hour, and a relative permittivity at 25°C and 1000 Hz within the range of 3 to 50.

[0011] Paragraph 2.

[0012] A fluorine-containing polymer film as described in Claim 1, having a surface roughness (Ra) of 350 nm or less.

[0013] Paragraph 3.

[0014] The residual polarization is 40 mC / m 2 A fluorine-containing polymer film as described in claim 1 or 2, which is less than or equal to the following.

[0015] Paragraph 4.

[0016] A fluorine-containing polymer film described in any one of claims 1 to 3, having an internal haze value of 30% or more.

[0017] Paragraph 5.

[0018] A fluorine-containing polymer film described in any one of claims 1 to 4, wherein the ratio of internal haze value [%] / film thickness [㎛] is within the range of 1 to 4.5.

[0019] Paragraph 6.

[0020] A fluorine-containing polymer film described in any one of claims 1 to 5, having a retardation [nm] / film thickness [㎛] ratio of 2.5 or less.

[0021] Paragraph 7.

[0022] In an X-ray diffraction pattern obtained when a film sample is directly placed in a sample holder having an opening and X-ray diffraction measurements are performed over a range where the diffraction angle 2θ is 10 to 40°,

[0023] A straight line connecting the diffraction intensity at a diffraction angle of 10° 2θ and the diffraction intensity at a diffraction angle of 25° 2θ is set as a baseline, and

[0024] The region enclosed by the baseline and the diffraction intensity curve is separated into two symmetry peaks by profile fitting, and

[0025] Among these, in the case where the side with the larger diffraction angle 2θ is recognized as the crystalline peak and the side with the smaller diffraction angle 2θ is recognized as the amorphous halo peak,

[0026] A fluorine-containing polymer film described in any one of claims 1 to 6, having a degree of crystallization of 50% or more as expressed by 100 × (area of ​​crystalline peaks) / (sum of the areas of crystalline peaks and amorphous halo peaks).

[0027] Paragraph 8.

[0028] A fluorine-containing polymer film described in any one of claims 1 to 7, wherein the fluorine-containing polymer is a vinylidene fluoride-based polymer.

[0029] Paragraph 9.

[0030] A fluorine-containing polymer film described in any one of claims 1 to 8, wherein the vinylidene fluoride-based polymer is a vinylidene fluoride / tetrafluoroethylene copolymer or a vinylidene fluoride / trifluoroethylene copolymer.

[0031] Paragraph 10.

[0032] A piezoelectric film composed of a fluorine-containing polymer film as described in any one of claims 1 to 9.

[0033] Paragraph 11.

[0034] A piezoelectric film made of a fluorine-containing polymer film,

[0035] The above fluorine-containing polymer film is a piezoelectric film satisfying (1) and (2) below:

[0036] (1) In the X-ray diffraction pattern obtained when a film sample is placed directly in a sample holder with an opening and X-ray diffraction measurements are performed over a range where the diffraction angle 2θ is 10 to 40°,

[0037] A straight line connecting the diffraction intensity at a diffraction angle of 10° 2θ and the diffraction intensity at a diffraction angle of 25° 2θ is set as a baseline, and

[0038] The region enclosed by the baseline and the diffraction intensity curve is separated into two symmetry peaks by profile fitting, and

[0039] Among these, in the case where the side with the larger diffraction angle 2θ is recognized as the crystalline peak and the side with the smaller diffraction angle 2θ is recognized as the amorphous halo peak,

[0040] The degree of crystallization, expressed as 100 × (area of ​​crystalline peaks) / (sum of the areas of crystalline peaks and amorphous halo peaks), is 50% or more.

[0041] (2) The fracture elongation is 400% or more.

[0042] Paragraph 12.

[0043] A piezoelectric film described in claim 11, wherein the ratio of the retardation [nm] / film thickness [㎛] of the above fluorine-containing polymer film is 2.5 or less.

[0044] Paragraph 13.

[0045] A piezoelectric film described in claim 11 or 12, wherein the surface roughness (Ra) of the fluorine-containing polymer film is 350 nm or less.

[0046] Paragraph 14.

[0047] The residual polarization of the above fluorine-containing polymer film is 40 mC / m 2 A piezoelectric film described in any one of claims 11 to 13, wherein

[0048] Paragraph 15.

[0049] A piezoelectric film described in any one of claims 11 to 14, wherein the internal haze value of the above-mentioned fluorine-containing polymer film is 20% or more.

[0050] Paragraph 16.

[0051] A piezoelectric film described in claim 15, wherein the ratio of the internal haze value [%] / film thickness [㎛] of the above fluorine-containing polymer film is within the range of 0.1 to 1.7.

[0052] Paragraph 17.

[0053] A piezoelectric film described in any one of claims 11 to 14, wherein the internal haze value of the above-mentioned fluorine-containing polymer film is 15% or less.

[0054] Paragraph 18.

[0055] A piezoelectric film described in claim 17, wherein the ratio of the internal haze value [%] / film thickness [㎛] of the above fluorine-containing polymer film is 0.4 or less.

[0056] Paragraph 19.

[0057] A piezoelectric film described in any one of claims 11 to 18, wherein the relative permittivity of the above-mentioned fluorine-containing polymer at 25°C and 1000 Hz is within the range of 3 to 50.

[0058] Paragraph 20.

[0059] A piezoelectric film described in any one of claims 11 to 19, wherein the above-mentioned fluorine-containing polymer is a vinylidene fluoride-based polymer.

[0060] Paragraph 21.

[0061] A piezoelectric film described in any one of claims 11 to 20, wherein the above-mentioned fluorine-containing polymer is a vinylidene fluoride / tetrafluoroethylene copolymer or a vinylidene fluoride / trifluoroethylene copolymer.

[0062] Paragraph 22.

[0063] A piezoelectric film described in any one of claims 10 to 21 for use in one or more selected from the group consisting of sensors, actuators, touch panels, haptic devices, vibration generators, speakers, and microphones.

[0064] Paragraph 23.

[0065] It is a laminate, and

[0066] A piezoelectric film described in any one of claims 10 to 21, and

[0067] A piezoelectric element having an electrode formed on at least one surface of the above-mentioned piezoelectric film.

[0068] In addition, the present disclosure also includes the following aspects.

[0069] · As a method for manufacturing a fluorine-containing polymer film,

[0070] (1) A process for preparing a liquid composition containing a fluorine-containing polymer and a solvent;

[0071] (2) A process of applying the above liquid composition onto a substrate; and

[0072] (3) A manufacturing method comprising a process of forming a film by exposing a substrate to the above liquid composition to a predetermined temperature.

[0073] · Process (3) is a manufacturing method in which the above-mentioned material is exposed for less than 1 hour within a range of 150 to 200°C, and then exposed for 5 hours or more within a range of 60°C or more and less than 150°C.

[0074] · Process (3) is a process of exposing the above-mentioned material to a temperature of 150 to 200°C for less than 1 hour, and then exposing it to a temperature of 50°C or lower, the above-mentioned manufacturing method. Effects of the invention

[0075] According to the present disclosure, a fluorine-containing polymer film having a low thermal shrinkage rate and a fluorine-containing polymer film having a high degree of crystallinity and a high elongation at break are provided. Brief explanation of the drawing

[0076] FIG. 1 is a schematic diagram showing an overview of the manufacturing apparatus used to manufacture the piezoelectric film of the example. Specific details for implementing the invention

[0077] The above overview of the present disclosure is not intended to describe each disclosed embodiment or all implementations of the present disclosure.

[0078] The latter description of the present disclosure illustrates embodiments of actual examples more specifically.

[0079] In some parts of this disclosure, guidance is provided by way of example, and this way of example may be used in various combinations.

[0080] In each case, the exemplified group can function as a non-exclusive and representative group.

[0081] All publications, patents, and patent applications cited in this specification are incorporated herein by reference as is.

[0082] terminology

[0083] Unless specifically limited, symbols and abbreviations in this specification may be understood in the sense commonly used in the technical field to which this disclosure belongs, according to the context of this specification.

[0084] In this specification, the phrase "contains" is used with the intent to include the phrases "essentially composed of" and "composed of".

[0085] Unless specifically limited, the processes, treatments, or operations described in this specification may be carried out at room temperature.

[0086] In this specification, room temperature may mean a temperature within the range of 10 to 40 ℃.

[0087] In this specification, the notation "C" n-m」(Here, n and m are each numbers.) indicates that, as commonly understood by those skilled in the art, the number of carbon atoms is n or more and m or less.

[0088] Fluorofluoride polymer film

[0089] The fluorine-containing polymer film of the present disclosure is a film containing a fluorine-containing polymer.

[0090] The fluorine-containing polymer has at least a fluorine-containing monomer unit. Specific examples of the fluorine-containing monomer include vinyl fluoride (VF), vinylidene fluoride (VDF), 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, perfluoropropylvinyl ether (PPVE), perfluoroacrylate, 2,2,2-trifluoroethylacrylate, 2-(perfluorohexyl)ethylacrylate, and combinations of two or more of these. Preferred examples of fluorine-containing monomers include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, and combinations of two or more of these.

[0091] The fluorine-containing polymer may additionally have fluorine-free monomer units. Specific examples of fluorine-free monomers include α-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., allylglycidyl ether); vinyl esters (e.g., vinyl acetate); acrylic acids, or esters thereof; methacrylic acids, or esters thereof; and combinations of two or more of these.

[0092] The ratio of fluorine-containing monomer units to the total monomer units of the fluorine-containing polymer may be, for example, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more. In addition, the ratio of said fluorine-containing monomer units may be, for example, 99 mol% or less, or 95 mol% or less.

[0093] The fluorine-containing polymer may preferably be a vinylidene fluoride-based polymer. The vinylidene fluoride-based polymer has at least one vinylidene fluoride unit (-CH2-CF2-). The vinylidene fluoride-based polymer may additionally have at least one other monomer unit selected from the group consisting of fluorine-containing monomer units other than vinylidene fluoride and fluorine-free monomer units.

[0094] Preferred examples of fluorine-containing monomers other than vinylidene fluoride include trifluoroethylene, tetrafluoroethylene, and combinations thereof.

[0095] The ratio of vinylidene fluoride units to the total monomer units of the vinylidene fluoride-based polymer may be, for example, 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, 35 mol% or more, 40 mol% or more, 45 mol% or more, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, or 75 mol% or more. The ratio of said vinylidene fluoride units may be, for example, 99 mol% or less, 95 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less.

[0096] The vinylidene fluoride-based polymer is preferably a vinylidene fluoride / tetrafluoroethylene copolymer or a vinylidene fluoride / trifluoroethylene copolymer.

[0097] In the vinylidene fluoride / tetrafluoroethylene copolymer, the molar ratio of vinylidene fluoride units (-CH2-CF2-) and tetrafluoroethylene units (-CF2-CF2-) is not limited, but may be in the range of, for example, 10 / 90 to 99 / 1. The molar ratio is preferably in the range of 60 / 40 to 97 / 3, more preferably in the range of 65 / 35 to 95 / 5, and particularly preferably in the range of 70 / 30 to 90 / 10.

[0098] In the vinylidene fluoride / trifluoroethylene copolymer, the molar ratio of vinylidene fluoride units (-CH2-CF2-) and trifluoroethylene units (-CF2-CHF-) is not limited, but may, for example, be in the range of 40 / 60 to 99 / 1. The molar ratio is preferably in the range of 50 / 50 to 97 / 3, more preferably in the range of 60 / 40 to 95 / 5, and particularly preferably in the range of 70 / 30 to 90 / 10.

[0099] The molar ratio of (repeating unit derived from tetrafluoroethylene) / (repeating unit derived from vinylidene fluoride) in the above "vinylidene fluoride / tetrafluoroethylene copolymer" is preferably in the range of 5 / 95 to 90 / 10, more preferably in the range of 5 / 95 to 75 / 25, even more preferably in the range of 15 / 85 to 75 / 25, and even more preferably in the range of 36 / 64 to 75 / 25.

[0100] Copolymers rich in vinylidene fluoride are desirable in that they have excellent solvent solubility and excellent processability of the film.

[0101] The molar ratio of (repeating unit derived from tetrafluoroethylene) / (repeating unit derived from vinylidene fluoride) in the above "vinylidene fluoride / tetrafluoroethylene copolymer" is preferably in the range of 5 / 95 to 37 / 63, more preferably in the range of 10 / 90 to 30 / 70, and even more preferably in the range of 5 / 85 to 25 / 75.

[0102] A copolymer with a higher amount of tetrafluoroethylene is desirable in that the film has excellent heat resistance.

[0103] The molar ratio of (repeating unit derived from tetrafluoroethylene) / (repeating unit derived from vinylidene fluoride) in the above "vinylidene fluoride / tetrafluoroethylene copolymer" is preferably in the range of 60 / 40 to 10 / 90, more preferably in the range of 50 / 50 to 25 / 75, and even more preferably in the range of 45 / 55 to 30 / 70.

[0104] The vinylidene fluoride / tetrafluoroethylene copolymer may be a copolymer composed of vinylidene fluoride and tetrafluoroethylene, or a copolymer essentially composed of vinylidene fluoride and tetrafluoroethylene.

[0105] The vinylidene fluoride / trifluoroethylene copolymer may be a copolymer composed of vinylidene fluoride and trifluoroethylene, or a copolymer essentially composed of vinylidene fluoride and trifluoroethylene.

[0106] The vinylidene fluoride / tetrafluoroethylene copolymer may additionally have at least one other monomer unit selected from the group consisting of fluorine-containing monomer units other than vinylidene fluoride and tetrafluoroethylene, and fluorine-free monomer units. The vinylidene fluoride / tetrafluoroethylene copolymer may contain the other monomer unit in an amount of, for example, 10 mol% or less of the total monomer units, preferably in the range of 0.01 to 5 mol%.

[0107] The vinylidene fluoride / trifluoroethylene copolymer may additionally have at least one other monomer unit selected from the group consisting of fluorine-containing monomer units other than vinylidene fluoride and trifluoroethylene, and fluorine-free monomer units. The vinylidene fluoride / trifluoroethylene copolymer may contain the other monomer unit in an amount of, for example, 10 mol% or less of the total monomer units, preferably in the range of 0.01 to 5 mol%.

[0108] The fluorine-containing polymer is preferably a polarized fluorine-containing polymer. In this specification, the term "polarized" means that an electric charge is imparted to the surface. That is, the polarized fluorine-containing polymer may be an electret, a piezoelectric, or a ferroelectric.

[0109] The fluorine-containing polymer film may additionally contain a polymer other than the fluorine-containing polymer. Specific examples of said polymer may include polycarbonate, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate), polyamide, silicone resin, polyether, polyvinyl acetate, polylactic acid, acrylic resin, methacrylate resin, and polyolefin (e.g., polyethylene, polypropylene). The said polymer may be a polymer other than acrylic resin and methacrylate resin, a polymer other than polyester, or a polymer other than acrylic resin, methacrylate resin, and polyester. With respect to the total polymer included in the fluorine-containing polymer film, the proportion of the polymer other than the fluorine-containing polymer may be, for example, less than 50 mass%, 45 mass% or less, 40 mass% or less, 35 mass% or less, 30 mass% or less, 25 mass% or less, 20 mass% or less, 15 mass% or less, or 10 mass% or less. The proportion of polymers other than the fluorine-containing polymer may be, for example, 0 mass%, 0.5 mass% or more, or 1 mass% or more.

[0110] Fluoropolymer films may contain commonly used additives.

[0111] Specific examples of additives include a filler (e.g., inorganic oxide particles), an affinity enhancer, a heat stabilizer, a UV absorber, a pigment, and a combination of one or more of these, and preferred examples include inorganic oxide particles and a combination of inorganic oxide particles and an affinity enhancer.

[0112] A preferred example of an inorganic oxide particle comprises at least one type selected from the group consisting of the following inorganic oxide particles (B1) to (B3).

[0113] [Inorganic oxide particles (B1)] Particles of oxides of metal elements of Group 2, 3, 4, 12, or 13 of the periodic table, or inorganic oxide composite particles thereof

[0114] Examples of the above metal elements include Be, Mg, Ca, Sr, Ba, Y, Ti, Zr, Zn, and Al.

[0115] A preferred example of (B1) includes particles of oxides of Be, Al, Mg, Y, and Zr. The particles are preferred because they are general-purpose, inexpensive, and also have high volume resistivity.

[0116] A more preferred example of (B1) comprises particles of at least one inorganic oxide selected from the group consisting of Al2O3, MgO, ZrO2, Y2O3, BeO, and MgO·Al2O3. The particles are preferred in that they have a high volume resistivity.

[0117] A more preferred example of (B1) includes Al2O3 with a γ-type crystal structure. The particles are preferred in that they have a large specific surface area and good dispersibility in fluorine-containing polymers.

[0118] [Inorganic oxide particles (B2)] Formula : M 1 a1 M 2b1 O c1 (during the meal, M 1 Silver is a Group 2 metallic element; M 2 is a Group 4 metallic element; a1 is in the range of 0.9 to 1.1; b1 is in the range of 0.9 to 1.1; c1 is in the range of 2.8 to 3.2; M 1 and M 2 particles of inorganic composite oxides represented by (each may be one or more metal elements).

[0119] Preferred examples of the above Group 2 metal elements include Mg, Ca, Sr, and Ba.

[0120] Preferred examples of the above Group 4 metal elements include Ti and Zr.

[0121] A preferred example of (B2) comprises particles of at least one inorganic oxide selected from the group consisting of BaTiO3, SrTiO3, CaTiO3, MgTiO3, BaZrO3, SrZrO3, CaZrO3, and MgZrO3. The particles are preferred in that they have a high volume resistivity.

[0122] [Inorganic oxide particles (B3)] Particles of oxides of metal elements of Group 2, 3, 4, 12, or 13 of the periodic table, and inorganic oxide composite particles of silicon oxide

[0123] Examples of the above metal elements include Be, Mg, Ca, Sr, Ba, Y, Ti, Zr, Zn, and Al.

[0124] A specific example of (B3) comprises particles of at least one inorganic oxide selected from the group consisting of 3A12O3·2SiO2, 2MgO·SiO2, ZrO2·SiO2, and MgO·SiO2.

[0125] Inorganic oxide particles do not necessarily have to be high dielectric, and can be appropriately selected depending on the application of the fluorine-containing polymer film. For example, by using general-purpose and inexpensive inorganic oxide particles [e.g., (B1), particularly Al2O3 particles and MgO particles], an improvement in volume resistivity can be achieved. The relative dielectric constant (1 kHz, 25 ℃) of these types of inorganic oxide particles (B1) is typically less than 100, preferably within the range of 10 or less.

[0126] As inorganic oxide particles, ferroelectric inorganic oxide particles [e.g., relative permittivity (1 kHz, 25 ℃) is 100 or higher] [e.g., (B2) and (B3)] may be used for the purpose of improving dielectric constant. Inorganic materials constituting ferroelectric inorganic oxide particles include complex metal oxides, their complexes, solid solutions, and sol-gel bodies, but are not limited to these.

[0127] The dielectric constant (25 ℃, 1 kHz) of the inorganic oxide particles is preferably within a range of 10 or more. In terms of increasing the dielectric constant of the fluorine-containing polymer film, the dielectric constant is preferably within a range of 100 or more, more preferably 300 or more. The upper limit of the dielectric constant is not particularly limited, but is typically around 3000.

[0128] The dielectric constant (ε) (25 ℃, 1 kHz) of the inorganic oxide particles is a value calculated by measuring the capacitance (C) using an LCR meter and using the equation C = ε×ε0×S / d (ε0: dielectric constant of vacuum) from the capacitance, electrode area (S), and thickness (d) of the sintered body.

[0129] It is preferable for the average primary particle size of the inorganic oxide particles to be small, and in particular, so-called nanoparticles with an average primary particle size of 1 μm or less are preferred. By uniformly dispersing these inorganic oxide nanoparticles, the electrical insulation properties of the fluorine-containing polymer film can be significantly improved with a small amount of formulation. The average primary particle size is preferably within the range of 800 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less. In terms of manufacturing difficulty, difficulty of uniform dispersion, and cost, the average primary particle size is preferably within the range of 10 nm or more, more preferably 20 nm or more, and even more preferably 50 nm or more.

[0130] The average primary particle size of inorganic oxide particles is calculated using a laser diffraction-scattering particle size distribution measuring device LA-920 (product name) (Horiba Manufacturing Co., Ltd.) or an equivalent product.

[0131] The fluorine-containing polymer film may contain 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 fluorine-containing polymer.

[0132] The lower limit of the above content is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, and even more preferably 1 part by mass, in terms of improving electrical insulation.

[0133] The upper limit of the above content is preferably 200 parts by mass, more preferably 150 parts by mass, and even more preferably 100 parts by mass, in order to uniformly disperse inorganic oxide particles in the fluorine-containing polymer and prevent a decrease in electrical insulation (withstand voltage) and tensile strength.

[0134] When high total light transmittance and low total haze values ​​are required for a fluorine-containing polymer film, it is preferable for the content to be small, and more preferable for it to be zero.

[0135] Fluoropolymer films may additionally contain an affinity enhancer when they contain inorganic oxide particles.

[0136] The affinity enhancer can increase the affinity between inorganic oxide particles and fluorine-containing polymers, uniformly disperse the inorganic oxide particles within the fluorine-containing polymers, firmly bind the inorganic oxide particles and the fluorine-containing polymers, suppress the occurrence of voids, and increase the dielectric constant.

[0137] Specific examples of affinity enhancers include coupling agents, surfactants, and epoxy group-containing compounds.

[0138] Examples of coupling agents include organic titanium compounds, organic silane compounds, organic zirconium compounds, organic aluminum compounds, and organic phosphorus compounds.

[0139] Examples of organic titanium compounds include organic titanium coupling agents (e.g., alkoxytitanium, titanium chelate, titanium acylate), and specific examples include tetraisopropyltitanate, titanium isopropoxyoctylene glycolate, diisopropoxybis(acetylacetonato)titanium, diisopropoxytitanium diisostearate, tetraisopropylbis(dioctylphosphite)titanate, and isopropyltri(n-aminoethyl-aminoethyl)titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(di-tridecyl)phosphitetitanate.

[0140] Preferred examples of organic titanium compounds include alkoxytitanium and titanium chelates, in that they have good affinity with inorganic oxide particles.

[0141] Organic silane compounds may be of high molecular weight or low molecular weight, and examples include alkoxysilanes (e.g., monoalkoxysilane, dialkoxysilane, trialkoxysilane, tetraalkoxysilane), vinylsilane, epoxysilane, aminosilane, methacroxysilane, and mercaptosilane. When alkoxysilane is used, further improvement in volume resistivity (improvement in electrical insulation properties), which is the effect of surface treatment, can be achieved through hydrolysis.

[0142] Examples of organic zirconium compounds include alkoxyzirconium and zirconium chelates.

[0143] Examples of organoaluminum compounds include alkoxyaluminum and aluminum chelates.

[0144] Examples of organic phosphorus compounds include phosphite esters, phosphate esters, and phosphate chelates.

[0145] The surfactant used as an affinity enhancer may be of a high molecular weight or a low molecular weight, but a high molecular weight is preferred in terms of thermal stability.

[0146] Examples of surfactants include nonionic surfactants, anionic surfactants, and cationic surfactants.

[0147] Examples of nonionic surfactants include polyether derivatives, polyvinylpyrrolidone derivatives, and alcohol derivatives, and a preferred example includes polyether derivatives in that they have good affinity with inorganic oxide particles.

[0148] Examples of anionic surfactants include polymers containing sulfonic acids and carboxylic acids and their salts, and preferred examples include acrylic acid derivative polymers and methacrylic acid derivative polymers in that they have good affinity with fluorine-containing polymers.

[0149] Examples of cationic surfactants include amine compounds, compounds having nitrogen-containing complex rings (e.g., imidazoline), and their halogenated salts.

[0150] The epoxy group-containing compound as an affinity enhancer may be a low molecular weight compound or a high molecular weight compound, and specific examples include epoxy compounds and glycidyl compounds, and preferred examples include a low molecular weight compound having one epoxy group in terms of affinity with a fluorine-containing polymer.

[0151] A more preferred example of an epoxy group-containing compound is the following formula:

[0152] [Chemical Formula 1]

[0153]

[0154] (In the formula, R represents a hydrocarbon group having 2 to 10 carbon atoms that may include a hydrogen atom, a methyl group, an oxygen atom, or a nitrogen atom, or an aromatic ring that may be substituted. l represents 0 or 1, m represents 0 or 1, and n represents an integer from 0 to 10.)

[0155] It includes compounds represented as.

[0156] 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:

[0157] [Chemical Formula 2]

[0158]

[0159] The content of the affinity enhancer may be in the range of preferably 0.01 to 30 parts by mass, more preferably 0.1 to 25 parts by mass, and even more preferably 1 to 20 parts by mass, with respect to uniform dispersion and high dielectric constant of the obtained fluorine-containing polymer film, based on 100 parts by mass of inorganic oxide particles.

[0160] The fluorine-containing polymer film may be a stretched or unstretched film, and it is preferable that it be an unstretched film. The fluorine-containing polymer film is preferably a cast film.

[0161] Thermal shrinkage rate

[0162] Thermal shrinkage rate refers to the thermal shrinkage rate in the direction of maximum shrinkage within the film surface.

[0163] Method for Determining Thermal Shrinkage Rate

[0164] Mark any two points on the sample film using an inkjet printer, and measure the length between the two points before and after heating using an optical microscope OLYMPUS STM6 or an equivalent. Additionally, heating is performed by placing the film in a heating oven at 90°C (a constant temperature dryer ETTAS ONW-300S or an equivalent) for one hour. The thermal shrinkage rate is obtained by the following formula:

[0165] Thermal shrinkage rate [%] = ((Length between 2 points before heating) - (Length between 2 points after heating) / (Length between 2 points before heating) × 100

[0166] In addition, any two of the above points are taken at intervals of 10 cm.

[0167] The upper limit of the heat shrinkage rate of the fluorine-containing polymer film may preferably be 0.4%, 0.35%, 0.3%, 0.25%, 0.2%, 0.15%, 0.1%, 0.07%, 0.05%, 0.03%, 0.01%, or 0%.

[0168] The lower limit of the above heat shrinkage rate may preferably be -0.4%, -0.35%, -0.3%, -0.25%, -0.2%, -0.15%, -0.1%, -0.07%, -0.05%, -0.03%, -0.01%, or 0%.

[0169] The above heat shrinkage rate may preferably be 0.4% or less, within the range of -0.3 to 0.3%, within the range of -0.2 to 0.25%, or within the range of -0.1 to 0.2%.

[0170] As described above, since the fluorine-containing polymer film has a low thermal shrinkage rate, it can be preferably used in applications where thermal shrinkage is a problem. Specific examples of said applications may include piezoelectric films, films for electronic devices, films for capacitors, films for displays, films for touch panels, films for electrical insulation, films for magnetic recording, films for packaging, films for construction, films for photography, and films for thermal transfer.

[0171] Relative permittivity

[0172] Method for Determining Non-Permittivity

[0173] Aluminum electrodes (film thickness about 300 Å) are fabricated on both sides of a sample film by vacuum heating deposition, and the capacitance (C) is measured using an LCR meter. From the capacitance, electrode area (S), and film thickness (d), the value is calculated by the formula C = ε×ε0×S / d (ε0 is the permittivity of vacuum).

[0174] The lower limit of the dielectric constant of the fluorine-containing polymer film can be, for example, 3.0, 3.5, or 4.0.

[0175] The upper limit of the above permittivity may be, for example, 50, 45, 40, 35, 30, 25, or 20.

[0176] The above dielectric constant may be, for example, within the range of 3.0 to 50, within the range of 3.5 to 45, or within the range of 4.0 to 20.

[0177] Surface roughness

[0178] Method for Determining Surface Roughness

[0179] The measurement of surface roughness (Ra) is performed in accordance with JIS B 0601-1994 using the VK-9710 manufactured by KEYENCE CORPORATION or an equivalent product, and the MUL00201 microscope manufactured by Nikon attached to the VK-9710 or an equivalent product. Here, the surface roughness is measured at five selected points on the film to exclude arbitrariness, and the arithmetic mean value is taken as the surface roughness.

[0180] The surface roughness of the fluorine-containing polymer film may be, for example, 350 nm or less, 300 nm or less, or 250 nm or less.

[0181] The above surface roughness may be, for example, 5 nm or more, 10 nm or more, or 12 nm or more.

[0182] The above surface roughness may be, for example, within a range of 5 to 350 nm, within a range of 10 to 300 nm, or within a range of 12 to 250 nm.

[0183] The ratio of surface roughness [nm] to film thickness [㎛] of a fluorine-containing polymer film can be, for example, 70 or less, 60 or less, or 50 or less.

[0184] The above ratio may be, for example, 0.001 or more, 0.002 or more, 0.003 or more, or 0.004 or more.

[0185] The above ratio may be, for example, within the range of 0.001 to 70, within the range of 0.003 to 60, or within the range of 0.004 to 50.

[0186] Residual polarization amount

[0187] Method for Determining Residual Polarization Amount

[0188] A sample film is obtained by patterning an aluminum electrode (flat electrode) by vacuum deposition on a 5 mm × 5 mm central portion of a film cut to 20 mm × 20 mm, and attaching two lead electrodes (3 mm × 80 mm) of aluminum foil reinforced with insulating tape to the flat electrode using conductive double-sided tape. This sample film, a function generator, a high-voltage amplifier, and an oscilloscope are combined in a sawtower circuit, and a triangular wave (maximum ±10 kV) is applied to the sample film. By measuring the response of the sample film using the oscilloscope, the amount of residual polarization at an applied electric field of 80 MV / m is obtained.

[0189] The residual polarization amount of the fluorine-containing polymer film is, for example, 100 mC / m 2 Below, 90 mC / m 2 Below, 80 mC / m 2 Below, 70 mC / m 2 Below, 60 mC / m 2 Below, 50 mC / m 2 Below, 40 mC / m 2 Less than, or 35 mC / m 2 It is as follows.

[0190] The above residual polarization amount is, for example, 5 mC / m 2 This is the ideal, and preferably 10 mC / m 2 Above, 15 mC / m 2 Above, 20 mC / m 2 Above, or 25 mC / m 2 It could be more than that.

[0191] The above residual polarization amount is, for example, 5 to 100 mC / m 2 Within the range of, 5 to 80 mC / m 2 Within the range of, 5 to 40 mC / m 2 Within the range of, or 5 to 35 mC / m 2 The range of can be tomorrow.

[0192] Internal haze value

[0193] Method for Determining Internal Haze Values

[0194] In this specification, the “inner haze value” is obtained by measuring the haze value in a haze test using a haze meter NDH7000SP CU2II (product name: Nippon Zenk Kogyo Co., Ltd.) or an equivalent product in accordance with ASTM D1003, by putting water into a glass cell and inserting a film therein.

[0195] The lower limit of the internal haze value of the fluorine-containing polymer film may be, for example, 0.01%, 0.05%, 0.1%, or 1%. Additionally, the lower limit of the internal haze value may be set to a higher value, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 55%.

[0196] The upper limit of the above internal haze value may be, for example, 90%, 85%, 80%, 75%, 70%, 65%, or 60%. Additionally, the upper limit of the internal haze value may be set to a lower value, for example, 15%, 10%, 5%, 4.5%, 4%, 3.5%, or 3%.

[0197] The above internal haze value may be, for example, 15% or less (e.g., within the range of 0.01 to 15%), 10% or less (e.g., within the range of 0.01 to 10%), or 5% or less (e.g., within the range of 0.01 to 5%, within the range of 0.05 to 4.5%, within the range of 0.1 to 4%), or 20% or more (e.g., within the range of 20 to 80%), or 30% or more (e.g., within the range of 30 to 80%, within the range of 40 to 80%, within the range of exceeding 50% and not exceeding 80%, or within the range of 55 to 80%).

[0198] Ratio of internal haze value [%] to film thickness [㎛]

[0199] The ratio of the internal haze value [%] / film thickness [㎛] of the fluorine-containing polymer film may be, for example, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, greater than 1, or 1.1 or more, and may be 0.01 or more, 0.05 or more, 0.1 or more, or 0.2 or more.

[0200] The ratio of the internal haze value [%] / film thickness [㎛] above may be, for example, 5 or less, 4.5 or less, 4 or less, 3.5 or less, 3 or less, 2.5 or less, 2 or less, 1.7 or less, or 1.5 or less, and may be 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less.

[0201] The ratio of the internal haze value [%] / film thickness [㎛] above may, for example, be within the range of 1 to 4.5, within the range of 1 to 4, within the range of 1 to 3.5, within the range of 1 to 3, or within the range of 1 to 2.5, or within the range of 0.1 to 1.7, or within the range of 0.7 to 1.5, or within the range of 0.4 or less, or within the range of 0.01 to 0.4.

[0202] retardation

[0203] Method for Determining Retardation

[0204] In this specification, retardation is determined by cutting a sample of the film into a size of 2 cm × 2 cm or larger and measuring it using a phase difference film / optical material inspection device RETS-100 (product name, Otsuka Electronics) or an equivalent product. In this specification, a value of 550 nm is adopted as the numerical value of retardation.

[0205] The lower limit of the retardation of the fluorine-containing polymer film is not specifically limited, but may be, for example, 0.5 nm, 1 nm, 2 nm, 4 nm, 5 nm, or 10 nm.

[0206] The upper limit of the above retardation may be, for example, 5000 nm, 4500 nm, 4000 nm, 3500 nm, 3000 nm, 2500 nm, 2000 nm, 1500 nm, 1000 nm, 500 nm, 400 nm, or 300 nm. Additionally, the upper limit of the above retardation may be 200 nm, 150 nm, 100 nm, or 50 nm. By setting the upper limit of the above retardation to these values, it has excellent optical isotropy and can be preferably used in optical devices. Furthermore, when used as a sensor, it can exhibit isotropic sensing characteristics.

[0207] The above retardation may preferably be within a range of 0.5 to 500 nm, more preferably within a range of 0.5 to 400 nm, and even more preferably within a range of 1 to 400 nm.

[0208] Ratio of retardation [nm] / film thickness [㎛]

[0209] The ratio of retardation [nm] / film thickness [㎛] is the value obtained by dividing the retardation determined by the above method by the film thickness determined by the above method.

[0210] The lower limit of the ratio of retardation [nm] / film thickness [㎛] of a fluorine-containing polymer film can be, for example, 0.02, 0.05, or 0.1.

[0211] The upper limit of the above ratio may be, for example, 2.5, 2.0, or 1.5.

[0212] The above ratio may be, for example, within the range of 0.02 to 2.5, or within the range of 0.05 to 2.0.

[0213] Crystallinity

[0214] Method for Determining Degree of Crystallinity

[0215] In an X-ray diffraction pattern obtained when a film sample is directly placed in a sample holder having an opening and X-ray diffraction measurements are performed over a range where the diffraction angle 2θ is 10 to 40°,

[0216] A straight line connecting the diffraction intensity at a diffraction angle of 10° 2θ and the diffraction intensity at a diffraction angle of 25° 2θ is set as a baseline, and

[0217] The region enclosed by the baseline and the diffraction intensity curve is separated into two symmetry peaks by profile fitting, and

[0218] Among these, in the case where the side with the larger diffraction angle 2θ is recognized as the crystalline peak and the side with the smaller diffraction angle 2θ is recognized as the amorphous halo peak,

[0219] The value expressed as 100 × (area of ​​crystalline peaks) / (sum of the area of ​​crystalline peaks and the area of ​​amorphous halo peaks) is called the degree of crystallinity.

[0220] The lower limit of the degree of crystallization of the fluorine-containing polymer film may be, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%.

[0221] The upper limit of the degree of crystallization above may be, for example, 90%, 85%, 80%, or 75%.

[0222] The degree of crystallization may be, for example, 50% or more, within the range of 50 to 90%, within the range of 55 to 90%, within the range of 60 to 90%, or within the range of 65 to 90%. Adjusting the degree of crystallization to such a range is desirable for obtaining a low thermal shrinkage rate. In addition, high elongation at break may be obtained while the degree of crystallization is within such a range.

[0223] Breaking believers

[0224] Method for Determining Breaking Believers

[0225] The measurement of the elongation at break is performed by cutting a film sample into 100 mm × 20 mm pieces, mounting the cut sample onto an Autograph manufactured by Shimadzu Corporation or an equivalent product using an air chuck (chuck pressure: 0.5 MPa), and conducting the measurement in accordance with ASTM-D-882 under conditions of a temperature of 23±2 ℃, a chuck length of 50 mm, and a tensile speed of 500 mm / min.

[0226] The elongation at break of the fluorine-containing polymer film may be, for example, 50% or more, or 100% or more, and preferably 400% or more, or 450% or more.

[0227] The above elongation at break may be, for example, 800% or less, or 750% or less, or 400% or less, or 350% or less.

[0228] The above elongation at break may be, for example, within a range of 50 to 400%, or within a range of 50 to 350%, or within a range of 400 to 800%, or within a range of 450 to 750%.

[0229] Film thickness

[0230] Method for Determining Film Thickness

[0231] In this specification, at 10 points every 1 cm in all directions along the entire planar direction of the film, the thickness is measured using a photoelectric digital measuring system (Digimicro MH-15M, manufactured by Nikon) or an equivalent product, and the average value is taken as the film thickness.

[0232] The lower limit of the film thickness of the fluorine-containing polymer film can be, for example, 5 μm, 9 μm, or 10 μm.

[0233] The upper limit of the above film thickness may be, for example, 3000 μm, 2500 μm, 2000 μm, 1500 μm, 1000 μm, 800 μm, 500 μm, 200 μm, 100 μm, or 60 μm.

[0234] The above film thickness may be, for example, within a range of 5 to 3000 μm, within a range of 5 to 2500 μm, within a range of 5 to 2000 μm, within a range of 5 to 1500 μm, within a range of 5 to 1000 μm, within a range of 5 to 800 μm, within a range of 5 to 500 μm, within a range of 5 to 200 μm, within a range of 5 to 100 μm, or within a range of 5 to 60 μm. The preferred film thickness may vary depending on the application of the piezoelectric film.

[0235] Coefficient of variation of film thickness

[0236] Method for Determining the Coefficient of Variation of Film Thickness

[0237] In this specification, the coefficient of variation of the value measured at 10 points every 1 cm along the entire planar direction of the film is defined as the coefficient of variation of the thickness.

[0238] The coefficient of variation of the thickness of the fluorine-containing polymer film can be preferably 10% or less, and more preferably 5% or less.

[0239] area

[0240] The area of ​​the fluorine-containing polymer film is 9 cm² in terms of industrial productivity. 2 It is desirable that it be within the above range. This range typically corresponds to the area range of a film manufactured by a roll-to-roll method.

[0241] The lower limit of the above area is preferably 10 cm 2 , 50 cm 2 , 100 cm 2 , 200 cm 2 , 300 cm 2 , 320 cm 2, 400 cm 2 , 500 cm 2 , 600 cm 2 , 700 cm 2 , 800 cm 2 , 900 cm 2 , 1000 cm 2 , 1100 cm 2 , 1200 cm 2 , 1300 cm 2 , 1400 cm 2 , 1500 cm 2 , or 1600 cm 2 It could be.

[0242] The upper limit of the above area is, for example, 4000 m² 2 , 3500 m 2 , 3000 m 2 , 2500 m 2 , 2000 m 2 , 1500 m 2 , 1000 m 2 , or 500 m 2 It could be.

[0243] The above area is, for example, 10 cm 2 ~ 4000 m 2 Within the range of, 100 cm 2 ~ 2000 m 2 Within the range of, or 600 cm 2 ~ 500 m 2 The range of can be tomorrow.

[0244] Piezoelectric constant d 33

[0245] <piezoelectric constant d 33 Method of determining

[0246] Piezoelectric constant d 33 The measurement is performed using the PIEZOTEST PM300 piezometer system (equipped with a pin having a tip of 1.5 mmφ as a sample fixing jig) or an equivalent product. Here, the piezoelectric constant d at 10 selected points on the film, excluding arbitrariness33 Measure , and the arithmetic mean value is the piezoelectric constant d 33 Selecting 10 points on the film without arbitrariness can be done, for example, by selecting 10 points at intervals of 50 mm along a straight line. Here, arbitrariness means intending to reduce the coefficient of variation described later.

[0247] Piezoelectric constant d 33 The actual measured value may be a positive or negative value depending on the front and back of the film being measured, but in this specification, the piezoelectric constant d 33 The absolute value is written as the value of.

[0248] Piezoelectric constant d of fluorine-containing polymer film 33 The lower limit of may be, for example, 0.5 pC / N, 1 pC / N, 3 pC / N, 5 pC / N, 7 pC / N, 10 pC / N, 15 pC / N, 17 pC / N, 18 pC / N, or 19 pC / N.

[0249] The above piezoelectric constant d 33 The upper limit of may be, for example, 35 pC / N, 30 pC / N, 28 pC / N, 26 pC / N, or 20 pC / N.

[0250] The above piezoelectric constant d 33 It may be, for example, within the range of 0.5 to 35 pC / N, within the range of 1 to 35 pC / N, within the range of 3 to 35 pC / N, within the range of 5 to 35 pC / N, within the range of 10 to 35 pC / N, within the range of 15 to 35 pC / N, within the range of 17 to 35 pC / N, within the range of 18 to 35 pC / N, or within the range of 19 to 35 pC / N.

[0251] Piezoelectric constant d 33 coefficient of variation

[0252] Piezoelectric constant d of fluorine-containing polymer film 33The coefficient of variation of is the piezoelectric constant d 33 It is the ratio of the standard deviation to the arithmetic mean.

[0253] The lower limit of the above coefficient of variation may be, for example, 0.0001, preferably 0.001, more preferably 0.01, and even more preferably 0.02 in terms of manufacturing costs.

[0254] The upper limit of the above coefficient of variation may be, for example, 2.0, preferably 1.0, more preferably 0.6, even more preferably 0.4, even more preferably 0.3, and particularly preferably 0.15 in terms of in-plane uniformity.

[0255] The above coefficient of variation may be, for example, within the range of 0.01 to 1.0, within the range of 0.01 to 0.6, within the range of 0.01 to 0.5, within the range of 0.01 to 0.4, or within the range of 0.01 to 0.3.

[0256] In one embodiment, the fluorine-containing polymer film preferably has the thermal shrinkage rate and the relative permittivity, and also the surface roughness, the residual polarization amount, the internal haze value, the ratio of the internal haze value [%] to film thickness [μm], the retardation, the ratio of the retardation [nm] to film thickness [μm], the degree of crystallization, the elongation at break, the film thickness, the coefficient of variation of the film thickness, the area, and the piezoelectric constant d 33 and the above piezoelectric constant d 33 It is desirable to have at least one type of physical property selected from the group consisting of the coefficient of variation of

[0257] In another embodiment, the fluorine-containing polymer film preferably has the degree of crystallinity and the elongation at break, and also includes the thermal shrinkage rate, the relative permittivity, the surface roughness, the amount of residual polarization, the internal haze value, the ratio of the internal haze value [%] to the film thickness [μm], the retardation, the ratio of the retardation [nm] to the film thickness [μm], the film thickness, the coefficient of variation of the film thickness, the area, and the piezoelectric constant d 33 , and the piezoelectric constant d 33 It is desirable to have at least one type of physical property selected from the group consisting of the coefficient of variation of

[0258] For example, it is preferable that a fluorine-containing polymer film satisfies any one of the following (a) to (s).

[0259] (a) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the surface roughness is 350 nm or less;

[0260] (b) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the residual polarization amount is 40 mC / m 2 below ;

[0261] (c) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the internal haze value is 30% or more;

[0262] (d) the thermal shrinkage rate is 0.4% or less, the relative permittivity is within the range of 3 to 50, the internal haze value is 30% or more, and the ratio of the internal haze value [%] to film thickness [㎛] is within the range of 1 to 4.5 (e.g., within the range of 1 to 4, within the range of 1 to 3.5, within the range of 1 to 3, within the range of 1 to 2.5);

[0263] (e) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the ratio of retardation [nm] / film thickness [㎛] is 2.5 or less (e.g., within the range of 0.002 to 2.5);

[0264] (f) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the degree of crystallization is 50% or more;

[0265] (g) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, the surface roughness is 350 nm or less, and the degree of crystallinity is 50% or more;

[0266] (h) The thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the residual polarization amount is 40 mC / m 2 Below, and the degree of crystallization above is 50% or more;

[0267] (i) the thermal shrinkage rate is 0.4% or less, the dielectric constant is within the range of 3 to 50, and the elongation at break is 400% or less;

[0268] (j) The degree of crystallization is 50% or more, the elongation at break is 400% or more, and the ratio of retardation [nm] / film thickness [㎛] is 2.5 or less (e.g., within the range of 0.002 to 2.5);

[0269] (k) the degree of crystallinity is 50% or more, the elongation at break is 400% or more, and the surface roughness is 350 nm or less;

[0270] (l) The degree of crystallization is 50% or more, the elongation at break is 400% or more, and the residual polarization is 40 mC / m 2 below ;

[0271] (m) the degree of crystallization is 50% or more, the elongation at break is 400% or more, and the internal haze value is 20% or more;

[0272] (n) the degree of crystallinity is 50% or more, the elongation at break is 400% or more, and the internal haze value is 20% or more, and the ratio of the internal haze value [%] / film thickness [㎛] is within the range of 0.1 to 1.7;

[0273] (o) the degree of crystallization is 50% or more, the elongation at break is 400% or more, and the internal haze value is 15% or less;

[0274] (p) The degree of crystallinity is 50% or more, the elongation at break is 400% or more, and the internal haze value is 15% or less, and the ratio of the internal haze value [%] / film thickness [㎛] is 0.4 or less (e.g., within the range of 0.01 to 0.4);

[0275] (q) the degree of crystallinity is 50% or more, the elongation at break is 400% or more, and the relative permittivity is within the range of 3 to 50;

[0276] (r) the degree of crystallinity is 50% or more, the elongation at break is 400% or more, and the ratio of retardation [nm] / film thickness [㎛] is 2.5 or less (e.g., within the range of 0.002 to 2.5), and the surface roughness is 350 nm or less; or

[0277] (s) the degree of crystallinity is 50% or more, the elongation at break is 400% or more, and the ratio of retardation [nm] / film thickness [㎛] is 2.5 or less (e.g., within the range of 0.002 to 2.5), and the residual polarization amount is 40 mC / m 2 below.

[0278] piezoelectric film

[0279] A piezoelectric film of one embodiment of the present disclosure is made of the above-mentioned fluorine-containing polymer film.

[0280] Piezoelectric films can be applied to various uses. Specific examples of uses include sensors (e.g., touch sensors, vibration sensors, biosensors, tire sensors (sensors installed on the inner surface of a tire), actuators, touch panels, haptic devices (devices that provide tactile feedback to a user), vibration power generation devices (e.g., vibration power generation floors, vibration power generation tires), speakers, and microphones.

[0281] manufacturing method

[0282] The fluorine-containing polymer film of the present disclosure is, for example,

[0283] Process A for preparing a nonpolarized fluorine-containing polymer film (e.g., an unoriented and nonpolarized fluorine-containing polymer film) by a casting method;

[0284] Process B for polarizing a nonpolarized fluorine-containing polymer film (e.g., an unoriented and also nonpolarized fluorine-containing polymer film); and

[0285] Process C of heat-treating a nonpolarized fluorinated polymer film (e.g., an unoriented and nonpolarized fluorinated polymer film) or heat-treating a fluorinated polymer film at any point in time with respect to Process B.

[0286] A manufacturing method comprising at least one of the following processes, preferably,

[0287] Manufacturing method comprising processes A to C

[0288] It can be manufactured by.

[0289] Process A (Film Preparation Process)

[0290] A method for manufacturing a non-polarized fluorine-containing polymer film by a casting method is, for example,

[0291] (1) A process for preparing a liquid composition by dissolving or dispersing the above-mentioned fluorine-containing polymer and the above-mentioned desired components (e.g., inorganic oxide particles and affinity enhancers) in a solvent to dissolve the liquid composition;

[0292] (2) A process of applying (flexing or coating) the above liquid composition onto a substrate; and

[0293] (3) A manufacturing method comprising a process of forming a film by exposing a substrate to the above liquid composition to a predetermined temperature. For industrial productivity, it is preferable to carry out these processes in a roll-to-roll manner.

[0294] The dissolution temperature in the preparation of the liquid composition is not particularly limited, but in terms of promoting dissolution and preventing discoloration of the film, it is preferably room temperature to 80°C.

[0295] In terms of preventing discoloration, 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 types. Additionally, it is preferable that the content of the amide-based solvent in the solvent be 50 mass% or less.

[0296] The application (or coating) of the above liquid composition onto a substrate may be carried out based on 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).

[0297] Among them, the gravure coating method or the slot die method is preferred due to ease of operation, small variation in the thickness of the resulting film, and excellent productivity.

[0298] For example, a polyethylene terephthalate (PET) film may be used as the above material.

[0299] The exposure of the substrate to the above liquid composition to a predetermined temperature may be carried out in accordance with the method of heat treatment (or heat drying) for conventional film formation. The heat treatment (or heat drying) may preferably be carried out, for example, by passing the substrate to which the above liquid composition has been applied through a high-temperature furnace (or drying furnace) in a roll-to-roll manner.

[0300] It is preferable to carry out the exposure of the substrate to a predetermined temperature to the above liquid composition in two or more stages (for example, within a range of 2 to 4 stages, preferably 2 or 3 stages, more preferably 2 stages).

[0301] The above exposure preferably includes the step of exposing the above material to a first temperature, and the step of exposing the material exposed to the first temperature to a second temperature lower than the first temperature.

[0302] The step of exposing to a first temperature may, for example, be a step of vaporizing the solvent of the liquid composition. The first temperature (or drying temperature) may, for example, be 150°C or higher, 155°C or higher, 160°C or higher, or 165°C or higher, and may be 230°C or lower, 220°C or lower, 210°C or lower, or 200°C or lower. The time of exposure to the first temperature (or drying time) is preferably short, more preferably less than 1 hour, and even more preferably 0.8 hours or less (for example, within the range of 0.3 to 0.8 hours).

[0303] The step of exposing to a second temperature may be, for example, a crystallization step or a crystal growth step (increasing the degree of crystallization). The second temperature is not particularly limited as long as it is lower than the first temperature, and may be, for example, 50°C or lower (preferably room temperature, or within the range of 20 to 50°C), or within the range of 60°C or higher and less than 150°C, preferably within the range of 80 to 145°C, more preferably within the range of 100 to 140°C, and even more preferably within the range of 110 to 140°C. The time of exposure to the second temperature may be, for example, 5 seconds or more, and a long time is also preferable, for example, 1 hour or more, preferably 2 hours or more, more preferably 3 hours or more, even more preferably 4 hours or more, even more preferably 5 hours or more, and particularly preferably 6 hours or more.

[0304] In particular, it is preferable to expose for a short time (e.g., less than 1 hour, preferably 0.3 to 0.8 hours) within a range of 150 to 200°C, and then expose for a long time (e.g., 5 hours or more, preferably 6 hours or more) within a range of 110°C or more and less than 150°C. By this treatment, a fluorine-containing polymer film having a low thermal shrinkage rate, high crystallinity, and high elongation at break can be formed.

[0305] In addition, it is also desirable to expose to a range of 150 to 200°C (e.g., less than 1 hour, preferably 0.3 to 0.8 hours) and then (preferably immediately after the above exposure) to a temperature of 50°C or lower (e.g., room temperature, or within a range of 20 to 50°C) (e.g., exposure for 5 seconds or more). By such treatment, a fluorine-containing polymer film having high crystallinity, high elongation at break, and low internal haze value can be formed.

[0306] The thickness of the non-polarizing film prepared in process A can be set according to the film to be obtained.

[0307] Process B (Polarization Process)

[0308] A non-polarized fluorine-containing polymer film used in a polarization treatment process (hereinafter simply referred to as "non-polarized film") is preferably not stretched.

[0309] Polarization treatment can be carried out by conventional methods, and preferably by corona discharge treatment.

[0310] For corona discharge, either negative corona or positive corona may be used, but it is preferable to use negative corona from the perspective of the ease of polarizing the non-polarized film.

[0311] Corona discharge treatment is not particularly limited, but can be performed by, for example, applying it to a non-polarizing film using a linear electrode as described in Japanese Patent Publication No. 2011-181748; applying it to a non-polarizing film using a needle electrode; or applying it to a non-polarizing film using a grid electrode.

[0312] The conditions for corona discharge treatment can be appropriately set based on common sense in the relevant technical field. If the corona discharge treatment conditions are excessively weak, there is a risk that the piezoelectricity of the resulting film will be insufficient; on the other hand, if the corona discharge treatment conditions are excessively strong, there is a risk that the resulting film will have point defects.

[0313] Here, the piezoelectric constant d of the obtained polarization film 33In order to suppress in-plane deviation, it is desirable that the distance between each needle electrode and / or line electrode and the film be constant, that is, that there is no (or very small) in-plane deviation of the distance between the electrode and the film (specifically, that the difference between the longest distance and the shortest distance is preferably within 6 mm, more preferably within 4 mm, and even more preferably within 3 mm).

[0314] Also, for example, when performing continuous roll-to-roll application, it is desirable to apply a constant tension to the film so that the film adheres to the roll appropriately and uniformly.

[0315] For example, when continuous roll-to-roll application is performed using a linear electrode, the DC electric field is, for example, within the range of -10 to -25 kV, although it varies depending on the distance between the linear electrode and the non-polarized film, the film thickness, etc. The processing speed is, for example, within the range of 10 to 1200 cm / min.

[0316] As another method, polarization treatment may be performed in addition to corona discharge, for example by applying it by sandwiching it between two sides of a non-polarizing film using flat electrodes. Specifically, for example, when applying it by sandwiching it between two sides of a non-polarizing film using flat electrodes, conditions of a DC electric field in the range of 0 to 400 MV / m (preferably 50 to 400 MV / m) and an application time in the range of 0.1 seconds to 60 minutes may be adopted.

[0317] Process C (Heat Treatment Process)

[0318] It is preferable that Process C be carried out as needed at any point relative to Process B. That is, Process C may be carried out before, simultaneously with, or after Process B. If Process C is carried out after Process B, the heat treatment of Process C may be carried out on the polarized film obtained in Process B or on the portion that has completed polarization in Process B. That is, the heat treatment of Process C may be carried out on the portion that has completed polarization treatment while the polarization treatment of Process B is being carried out. The heat treatment is not particularly limited, but, for example, the above-mentioned fluorine-containing polymer film (hereinafter simply referred to as the above-mentioned film) may be placed between two metal plates and said metal plates may be heated; said roll of said film may be heated in a constant temperature bath; or in the production of said film by a roll-to-roll method, a metal roll may be heated and said film may be brought into contact with said heated metal roll; Alternatively, it is preferable to include passing the above film through a heated furnace in a roll-to-roll manner. Here, when process C is performed after process B, the polarization film may be heat-treated as a single unit, or a laminated film may be formed by stacking it on a different type of film or metal foil and then heat-treating it. In particular, when heat-treating at a high temperature, the latter method is preferable because it is less likely for wrinkles to form on the polarization film.

[0319] The temperature of the above heat treatment may vary depending on the type of polarization film being heat-treated, and preferably is within the range of (melting point of the polarization film being heat-treated - 100) ℃ to (melting point of the polarization film being heat-treated + 40) ℃.

[0320] The temperature of the heat treatment above is, specifically, preferably within the range of 80 ℃ or higher, more preferably 85 ℃ or higher, and even more preferably 90 ℃ or higher.

[0321] In addition, the temperature of the heat treatment is preferably within the range of 170 ℃ or less, more preferably 160 ℃ or less, and even more preferably 140 ℃ or less.

[0322] The time of the heat treatment is typically within the range of 10 seconds or more, preferably 0.5 minutes or more, more preferably 1 minute or more, and even more preferably 2 minutes or more.

[0323] In addition, the upper limit of the time for the above heat treatment is not limited, but typically, the time for the above heat treatment is within the range of 60 minutes or less.

[0324] The conditions of the above heat treatment are preferably within a range of 90°C or higher for 1 minute or more.

[0325] The heat treatment typically includes cooling the film to a predetermined temperature. The temperature is preferably within the range of 0°C to 60°C and may be room temperature. The cooling rate may be slow cooling or rapid cooling, and rapid cooling is preferable in terms of productivity. Rapid cooling may be carried out, for example, by means such as blowing air. In this specification, such heat treatment of the film may be referred to as an annealing treatment.

[0326] The film obtained in this way possesses high piezoelectricity even after annealing, and furthermore, even after the manufacturing process of the piezoelectric material includes heat treatment.

[0327] Roll of fluorine-containing polymer film

[0328] Fluoropolymer films can preferably be stored and shipped as rolls.

[0329] A roll of one embodiment of the present disclosure may consist only of the film, may be in the form of a protective film laminated on the film and wound, or may have a core such as a paper tube and the film wound on the core.

[0330] The roll of the above film is preferably within a range of at least 50 mm in width and at least 20 m in length.

[0331] The roll of the above film can be prepared, for example, by winding the film using a winding roller and a winding roller.

[0332] Here, from the perspective of suppressing the bending of the film, it is desirable to make the unwinding roller and the winding roller parallel, as is commonly practiced.

[0333] As for the 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 fluoropolymer, a plated roller, or a roller coated with a release agent.

[0334] Here, if the film thickness is non-uniform, non-uniformity in the thickness of the roll occurs, such as the so-called high edge (where the end becomes thicker than the center in the axial direction of the roll; where both ends become concave compared to the center when the film thickness is lower than the center; or where the end on the thinner side becomes concave when the thickness changes obliquely from one end to the other), and this can be a cause of wrinkles. In addition, this can be a cause of film bending (bending in the absence of tension other than that caused by gravity) when unwinding the film.

[0335] Generally, to prevent roll earing, the edges of the film end at the roll are slit using a slitter; however, if the film thickness is uneven over a wide area extending from the film end, it is difficult to prevent roll earing and concave areas by slitting the edges alone.

[0336] In addition, generally, the wider the film width (e.g., width 100 mm or more) and the longer the film length (e.g., length 50 m or more), the more likely the above-mentioned ear formation, the above-mentioned concave portion, and the above-mentioned bending are to occur. However, since the piezoelectric film has high uniformity of thickness, the roll can be made in which the above-mentioned ear formation, the above-mentioned concave portion, and the above-mentioned bending are suppressed, even in cases where the film width is wide (e.g., width 100 mm or more) and the film length is long (e.g., length 50 m or more), either as is or by simply cutting the edges of the film end that becomes the end of the roll with a slitter (slitting).

[0337] The edge (film edge) removed by the slit can be recovered and recycled as a raw material for the film.

[0338] The roll of the above film has high uniformity of 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 within the range of 70 to 130%. As a result, the bending of the film released from the roll of the above film is suppressed.

[0339] In addition, the roller used in the manufacture of the above film and the roll is preferably made of at least polytetrafluoroethylene (PTFE), chrome plating, or stainless steel (SUS) for its surface material.

[0340] By these factors, wrinkles in the film can be suppressed.

[0341] piezoelectric

[0342] A piezoelectric body of one embodiment of the present disclosure is a laminate and comprises a piezoelectric film and an electrode formed on at least one surface of the piezoelectric film.

[0343] Specific examples of the above electrode include an ITO (indium tin oxide) electrode, a tin oxide electrode, an aluminum electrode, a metal nanowire, a metal nanoparticle (e.g., silver nanoparticle), and an organic conductive resin.

[0344] The above piezoelectric element may be a laminate comprising the piezoelectric film, an electrostatic electrode layer (or upper electrode layer) formed on one surface of the piezoelectric film, and a negative electrode layer (or lower electrode layer) formed on the other surface of the piezoelectric film.

[0345] The above piezoelectric body may have an insulating layer on the side where the piezoelectric film of the electrode layer is not laminated. In addition, the above piezoelectric body may have a cover (e.g., an electronic shield layer) on the side (or outermost surface) where the piezoelectric film of the electrode layer is not laminated.

[0346] A method for manufacturing a piezoelectric material is, for example,

[0347] Process for preparing the above piezoelectric film; and

[0348] A process of forming an electrode on at least one surface of the above-mentioned piezoelectric film

[0349] It includes.

[0350] In the process of forming the electrode, the method of forming the electrode typically includes heat treatment, and specific examples thereof include a method of forming a film of an electrode material by a physical vapor phase growth method (e.g., vacuum deposition, ion plating, sputtering) or a chemical vapor phase growth method (e.g., plasma CVD), and a method of applying the electrode material to a substrate.

[0351] The lower limit of the temperature of the above heat treatment is, for example, 25 ℃, preferably 40 ℃, more preferably 50 ℃.

[0352] The upper limit of the temperature of the above heat treatment is (melting point of the polarized film being heat-treated - 3°C), for example, 220°C, preferably 180°C, more preferably 150°C, and even more preferably 130°C.

[0353] The temperature of the heat treatment above may be, for example, within a range of 25 to 220 ℃, preferably within a range of 40 to 130 ℃. Even if the heat treatment is performed at such a heat treatment temperature, the decrease in piezoelectricity can be significantly suppressed.

[0354] The time of the heat treatment is typically within the range of 10 seconds or more, preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more.

[0355] Examples

[0356] Hereinafter, an embodiment of the present disclosure will be described in more detail by way of examples, but the present disclosure is not limited thereto.

[0357] In the embodiments described below, the following electrodes were used.

[0358] <Electrode used>

[0359] (1) A needle electrode rod having electrode needles (needle electrodes) (R = 0.06 mm; manufactured by Morita Needle Manufacturing Co.) formed in a single row at 10 mm intervals along the centerline of a brass rod 20 mm wide (thickness 10 mm, length 500 mm).

[0360] (2) Similar to (1), a needle-shaped electrode rod having electrode needles (R = 0.06 mm; manufactured by Morita Needle Factory) formed in a single row at 15 mm intervals.

[0361] (3) A gold-plated tungsten linear electrode with a diameter of 0.1 mm (length 500 mm)

[0362] In the piezoelectric film described below, the thermal shrinkage rate, relative permittivity, surface roughness, amount of remanent polarization, internal haze value, retardation, degree of crystallinity, elongation at break, film thickness, and piezoelectric constant d are, by the following method 33 Measured.

[0363] <Thermal Shrinkage Rate>

[0364] The film was cut to A4 size, and on the cut film, a 10 cm square with the MD and TD directions oriented vertically and horizontally was marked at its vertices using an inkjet printer. The side lengths before and after heating were measured using an optical microscope (small measuring microscope OLYMPUS STM6). Additionally, heating was performed by placing the film in a heating furnace (constant temperature dryer ETTAS ONW-300S) at 90°C for 1 hour. The thermal shrinkage rate was calculated using the following formula:

[0365] Thermal shrinkage rate [%] = ((Side length before heating) - (Side length after heating)) / (Side length before heating) × 100

[0366] Non-permittivity

[0367] Aluminum electrodes (film thickness about 300 Å) were fabricated on both sides of a sample film by vacuum heating deposition, and the capacitance (C) was measured using an LCR meter. From the capacitance, electrode area (S), and film thickness (d), the value was calculated using the formula C = ε×ε0×S / d (ε0 is the permittivity of vacuum).

[0368] <Surface Roughness>

[0369] The measurement of surface roughness (Ra) was performed in accordance with JIS B 0601-1994 using the VK-9710 manufactured by KEYENCE CORPORATION and the MUL00201 microscope manufactured by Nikon attached to the VK-9710. In this measurement, the surface roughness was measured at five selected points on the film to exclude arbitrariness, and the surface roughness was calculated from the average value.

[0370] Residual polarization amount

[0371] An aluminum electrode (flat electrode) was patterned by vacuum deposition on a 5 mm × 5 mm central portion of a sample film cut to 20 mm × 20 mm. Two lead electrodes (3 mm × 80 mm) made of aluminum foil, reinforced with insulating tape, were attached to this flat electrode using conductive double-sided tape. This sample film, a function generator, a high-voltage amplifier, and an oscilloscope were combined in a Sawyer Tower circuit, and a triangular wave (maximum ±10 kV) was applied to the sample film. By measuring the response of the sample film using an oscilloscope, the amount of residual polarization at an applied electric field of 80 MV / m was determined.

[0372] <Internal Haze Value>

[0373] Water was placed in a quartz cell, a film was inserted therein, and measurements were taken in accordance with ASTM D1003 using NDH7000SP CU2II (product name, Nippon Dense Industry).

[0374] Retardation

[0375] The retardation was determined by cutting a sample of the film into a size of 2 cm × 2 cm or larger and measuring it using the phase difference film / optical material inspection device RETS-100 (product name, Otsuka Electronics). A value of 550 nm was adopted for the retardation value.

[0376] Crystallization degree

[0377] A film sample was placed directly in a sample holder with an opening formed therein, and X-ray diffraction measurements were performed over a range of 10 to 40° for a diffraction angle 2θ. In the obtained X-ray diffraction pattern, a straight line connecting the diffraction intensity at a diffraction angle 2θ of 10° and the diffraction intensity at a diffraction angle 2θ of 25° was set as the baseline, and the region enclosed by the baseline and the diffraction intensity curve was separated into two symmetry peaks by profile fitting, and among these, the one with the larger diffraction angle 2θ was recognized as the crystalline peak, and the one with the smaller diffraction angle 2θ was recognized as the amorphous halo peak.

[0378] The degree of crystallinity was calculated by 100 × (area of ​​the crystalline peak) / (sum of the area of ​​the crystalline peak and the area of ​​the amorphous halo peak).

[0379] <Padan Shindo>

[0380] For measuring the elongation at break, a film sample was cut to 100 mm × 20 mm, and the cut sample (N = 5) was mounted on an Autograph manufactured by Shimadzu Corporation using an air chuck (chuck pressure: 0.5 MPa), and measured according to ASTM-D-882 under conditions of a temperature of 23±2 ℃, a chuck length of 50 mm, and a tensile speed of 500 mm / min.

[0381] Film thickness

[0382] The film thickness was measured at 10 points every 1 cm along the entire planar direction of the film using a photoelectric digital measuring system (Digimicro MH-15M, manufactured by Nikon), and the film thickness was calculated from the average value.

[0383] <piezoelectric constant d 33 >

[0384] Piezoelectric constant d 33The measurement was performed using the PM300 piezometer system from PIEZOTEST. In this measurement, the sample was clipped with 1 N, and the generated charge was read when a force of 0.25 N and 110 Hz was applied.

[0385] (1) Manufacturing of piezoelectric film

[0386] <Piezoelectric Film 1>

[0387] Piezoelectric film 1 was manufactured by a casting method. Specifically, piezoelectric film 1 was obtained by applying a methyl ethyl ketone solution of 24 wt% (molar ratio 80:20) of vinylidene fluoride / tetrafluoroethylene copolymer onto a PET substrate film, treating it at 190°C for 0.5 hours to vaporize the solvent, then lowering the temperature to 120°C and maintaining it for 5 hours, then cooling it to room temperature, and performing the polarization treatment described below.

[0388] Piezoelectric Film 2

[0389] Piezoelectric film 2 was manufactured by a casting method. Specifically, piezoelectric film 2 was obtained by applying a methyl ethyl ketone solution of 24 wt% (molar ratio 80:20) of vinylidene fluoride / tetrafluoroethylene copolymer onto a PET substrate film, treating it at 190°C for 0.5 hours to vaporize the solvent, then lowering the temperature to 120°C and maintaining it for 6 hours, then cooling it to room temperature, and performing the polarization treatment described below.

[0390] <Piezoelectric Film 3>

[0391] Piezoelectric film 3 was manufactured by a casting method. Specifically, piezoelectric film 3 was obtained by applying a methyl ethyl ketone solution of 10 wt% (molar ratio 70:30) of vinylidene fluoride / tetrafluoroethylene copolymer onto a PET substrate film, treating it at 190°C for 0.5 hours to vaporize the solvent, then lowering the temperature to 125°C and maintaining it for 5 hours, then cooling it to room temperature, and performing the polarization treatment described below.

[0392] <Piezoelectric Film 4>

[0393] Piezoelectric film 4 was manufactured by a casting method. Specifically, piezoelectric film 4 was obtained by applying a methyl ethyl ketone solution of 20 wt% (molar ratio 79:21) of vinylidene fluoride / trifluoroethylene copolymer onto a PET substrate film, treating it at 190°C for 0.5 hours to vaporize the solvent, then lowering the temperature to 130°C and maintaining it for 5 hours, then cooling it to room temperature, and performing the polarization treatment described below.

[0394] <Piezoelectric Film 5>

[0395] Piezoelectric film 5 was manufactured by a casting method. Specifically, piezoelectric film 5 was obtained by applying a methyl ethyl ketone solution of 20 wt% (molar ratio 79:21) of vinylidene fluoride / trifluoroethylene copolymer onto a PET substrate film, treating it at 180°C for 0.5 hours to vaporize the solvent, maintaining it at room temperature immediately, and then performing the polarization treatment described below.

[0396] polarization treatment

[0397] In an ISO Class 7 cleanroom (humidity 60%), as shown in the overview in FIG. 1, a vinylidene fluoride / tetrafluoroethylene copolymer film (2) (hereinafter simply referred to as film (2)) having a width of 550 mm, a length of 200 m, and a film thickness (20 to 40 μm) as shown in Table 1 was installed on a ground electrode made of SUS, which is an earthed roller (1) (diameter 200 mm, width 800 mm), so as to move along the roller (1) at a wrap angle of 200°. As a first electrode (E1), a needle electrode is installed so that the row of the needle electrode is perpendicular to the surface of the roller (1) (i.e., in the direction of the radius of motion of the roller (1)), and also so that the tip of the needle electrode (first electrode (E1)) is positioned 10 mm above the film (2). The first electrode (E1) is connected to a first high-voltage power source (V1). Additionally, at positions 100 mm and 150 mm away from the needle electrode (first electrode (E1)) in terms of the length of the film (2), a gold-plated tungsten linear electrode (length 550 mm) with a diameter of 0.1 mm is installed as a second electrode (E2), respectively, so that it is positioned 20 mm above the film (2). Each second electrode (E2) is connected to a second high-voltage power source (V2).

[0398] After applying a voltage of -10 kV to the needle electrode (first electrode (E1)) and a voltage of -10 to -16 kV to the linear electrode (second electrode (E2)), the film (2) was moved at a speed of 96 cm / min in the direction of the arrow in Fig. 1 to pass corona discharge generated from the tip of the needle electrode (first electrode) and the linear electrode (second electrode) connected thereto, and the film (2) was also brought into contact with an earthed metal roll (3) (diameter 70 mm) to neutralize the charge. After that, using a slitter, the ends of the film (2) were each cut by a width of 0.5 cm, and the obtained polarized film was wound onto a cylindrical core with a diameter of 6 inches while a PET film was sandwiched between them. A polarized film was manufactured.

[0399] Here, the distance between the needle 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 is 0 mm).

[0400] (2) Evaluation of piezoelectric film

[0401] The evaluation results of the piezoelectric film manufactured according to the present embodiment are shown in Table 1 below.

[0402]

Claims

Claim 1 A fluorine-containing polymer film having a thermal shrinkage rate of 0.4% or less after heating at 90°C for 1 hour and a relative permittivity at 25°C and 1000 Hz within the range of 3 to 50, wherein the fluorine-containing polymer is a vinylidene fluoride-based polymer, and the fluorine-containing polymer film is manufactured by undergoing two or more stages of exposure, comprising the step of exposing a substrate to which a liquid composition containing the fluorine-containing polymer is applied to a first temperature, and the step of exposing the substrate exposed to the first temperature to a second temperature lower than the first temperature. Claim 2 A fluorine-containing polymer film according to claim 1, having a surface roughness (Ra) of 350 nm or less. Claim 3 In claim 1, the residual polarization amount is 40 mC / m 2 Lee Ha-in, fluorine-containing polymer film. Claim 4 A fluorine-containing polymer film having an internal haze value of 30% or more, according to claim 1. Claim 5 A fluorine-containing polymer film according to claim 1, wherein the ratio of internal haze value [%] / film thickness [㎛] is within the range of 1 to 4.

5. Claim 6 A fluorine-containing polymer film according to claim 1, wherein the ratio of retardation [nm] / film thickness [㎛] is 2.5 or less. Claim 7 A fluorine-containing polymer film having a degree of crystallization of 50% or more, wherein, in the X-ray diffraction pattern obtained by directly placing a film sample in a sample holder with an opening formed therein and performing X-ray diffraction measurements over a range where the diffraction angle 2θ is 10 to 40°, a straight line connecting the diffraction intensity at a diffraction angle 2θ of 10° and the diffraction intensity at a diffraction angle 2θ of 25° is set as a baseline, and the region enclosed by the baseline and the diffraction intensity curve is separated into two symmetry peaks by profile fitting, wherein the one with the larger diffraction angle 2θ is recognized as a crystalline peak and the one with the smaller diffraction angle 2θ is recognized as an amorphous halo peak, and the one with the smaller diffraction angle 2θ is recognized as an amorphous halo peak. Claim 8 delete Claim 9 A fluorine-containing polymer film according to claim 1, wherein the vinylidene fluoride-based polymer is a vinylidene fluoride / tetrafluoroethylene copolymer or a vinylidene fluoride / trifluoroethylene copolymer. Claim 10 A piezoelectric film comprising a fluorine-containing polymer film as described in any one of claims 1 to 7 and 9. Claim 11 A piezoelectric film comprising a fluorine-containing polymer film, wherein the fluorine-containing polymer is a vinylidene fluoride-based polymer, and wherein the fluorine-containing polymer film is manufactured by undergoing two or more stages of exposure, including the step of exposing a substrate to which a liquid composition containing the fluorine-containing polymer is applied to a first temperature, and the step of exposing the substrate exposed to the first temperature to a second temperature lower than the first temperature, and wherein the fluorine-containing polymer film satisfies the following (1) and (2): (1) In an X-ray diffraction pattern obtained when a film sample is directly placed in a sample holder having an opening and X-ray diffraction measurements are performed over a range in which the diffraction angle 2θ is 10 to 40°, a straight line connecting the diffraction intensity at a diffraction angle 2θ of 10° and the diffraction intensity at a diffraction angle 2θ of 25° is set as a baseline, and wherein When the region enclosed by the baseline and the diffraction intensity curve is separated into two symmetry peaks by profile fitting, and the one with the larger diffraction angle 2θ is recognized as the crystalline peak and the one with the smaller diffraction angle 2θ is recognized as the amorphous halo peak, the degree of crystallization is 50% or more, expressed as 100 × (area of ​​the crystalline peak) / (sum of the area of ​​the crystalline peak and the area of ​​the amorphous halo peak), (2) the elongation at break is 400% or more. Claim 12 A piezoelectric film according to claim 11, wherein the ratio of the retardation [nm] / film thickness [㎛] of the fluorine-containing polymer film is 2.5 or less. Claim 13 A piezoelectric film according to claim 11 or 12, wherein the surface roughness (Ra) of the fluorine-containing polymer film is 350 nm or less. Claim 14 In claim 11 or 12, the residual polarization amount of the fluorine-containing polymer film is 40 mC / m 2 Lee Ha-in, piezoelectric film. Claim 15 A piezoelectric film according to claim 11 or 12, wherein the internal haze value of the fluorine-containing polymer film is 20% or more. Claim 16 A piezoelectric film according to claim 15, wherein the ratio of the internal haze value [%] / film thickness [㎛] of the fluorine-containing polymer film is within the range of 0.1 to 1.

7. Claim 17 A piezoelectric film according to claim 11 or 12, wherein the internal haze value of the fluorine-containing polymer film is 15% or less. Claim 18 A piezoelectric film according to claim 17, wherein the ratio of the internal haze value [%] / film thickness [㎛] of the fluorine-containing polymer film is 0.4 or less. Claim 19 A piezoelectric film according to claim 11 or 12, wherein the relative permittivity of the fluorine-containing polymer at 25°C and 1000 Hz is within the range of 3 to 50. Claim 20 delete Claim 21 A piezoelectric film according to claim 11 or 12, wherein the fluorine-containing polymer is a vinylidene fluoride / tetrafluoroethylene copolymer or a vinylidene fluoride / trifluoroethylene copolymer. Claim 22 In claim 10, a piezoelectric film for use in one or more selected from the group consisting of sensors, actuators, touch panels, haptic devices, vibration generators, speakers, and micros. Claim 23 A piezoelectric body comprising a laminate, a piezoelectric film as described in claim 10, and an electrode formed on at least one surface of the piezoelectric film. Claim 24 A piezoelectric body comprising a laminate, a piezoelectric film as described in claim 11, and an electrode formed on at least one surface of the piezoelectric film.

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