JP2009038089A - High dielectric film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high dielectric film which can be made thin having a high dielectric property, and has a superior winding property (flexibility) and small dielectric loss. <P>SOLUTION: Provided is the high dielectric film which contains a vinylidene fluoride polymer (A) and compound oxide particles (B) containing at least three kinds of metal elements selected from a group of group II metal elements and group IV metal elements in a periodic table, the high dielectric film containing 10 to 500 parts by mass of the compound oxide particles (B) for 100 parts by mass of the vinylidene fluoride polymer (A). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high dielectric film useful as a dielectric film for film capacitors, for example.

  In recent years, plastic insulators are characterized by high insulation resistance, excellent frequency characteristics, and excellent flexibility, so they are used for communication, electronic equipment, power, medium / low-pressure phase advance, and inverter. It is expected as a film capacitor. Film capacitors include wireless communication devices for aircraft, ships, vehicles, etc., consumer equipment such as TVs, radios, audios, etc., for driving small motors such as air conditioners, washing machines, electric fans, etc., and for improving the power rate of fluorescent lamps, mercury lamps, etc. Used for etc.

  A film capacitor is usually composed of a film in which aluminum or zinc is vapor-deposited on the surface, or an aluminum foil and a film laminated in multiple layers. In recent years, many types of film capacitors, in which electrodes are formed on a film by metal vapor deposition, have been used.

  As films for film capacitors, polypropylene (PP), polyethylene terephthalate (PET) and polyphenylene sulfide (PPS) films have been studied so far (for example, see Patent Document 1). However, these films had a low dielectric constant of about 2.5 to 3. Since the capacitance of film capacitors is proportional to the dielectric constant and inversely proportional to the film thickness, the thinning of these films has been mainly studied so far. However, if the film is made too thin, it will be difficult to produce and the insulation voltage will decrease. There is a limit. The film capacitor is required to be further reduced in size and capacity, and therefore there is a great demand for a high dielectric constant thin film.

  Until now, as a high dielectric film, a polyvinylidene fluoride (PVdF) film and a film using cyanoethylated pullulan have been studied (for example, see Patent Documents 2 to 4). It was less than 20, and it was difficult to reduce the thickness.

  Further, in order to produce a film having a higher dielectric constant, a method of forming a film by mixing a barium titanate or lead zirconate, which is an inorganic ferroelectric particle having a high dielectric constant, and a resin has been studied.

One of them is a technique in which a resin and inorganic ferroelectric fine particles are melt-kneaded and formed into a film by melt extrusion or inflation molding (see, for example, Patent Documents 5 to 8). However, with this approach,
(1) It is difficult to reduce the film thickness to 10 μm or less. (2) Since there are two problems that voids are easily generated, a thin film having a dielectric constant of 20 or more and a film thickness of 9 μm or less has not been obtained. is there.

  As another method, there is a method in which a resin and inorganic ferroelectric fine particles are mixed in a solution and a thin film is formed by coating (see, for example, Patent Documents 9 to 10). In Patent Documents 9 and 10, ferroelectric fine particles are dispersed and coated in at least one polymer selected from the group consisting of aromatic polyamide and aromatic polyimide, and a film having a dielectric constant of 20 and a film thickness of 10 μm is obtained by peeling. Is able to. However, when the film thickness is 5 μm, only a film having a dielectric constant of 15 is obtained, and when the film thickness is 3 μm, only a film having a dielectric constant of 11 is obtained. That is, a thin film having a dielectric constant of 20 or more and a film thickness of 9 μm or less has not been obtained. Further, since polyamide or polyimide is used as the polymer, the film has low flexibility.

  Further, when barium titanate or lead zirconate titanate is used as the inorganic ferroelectric fine particles, the dielectric loss is high in the frequency region of about several tens Hz to several tens kHz, and furthermore, the temperature coefficient of dielectric loss is high. Even if the dielectric constant was high, the characteristics could not be utilized.

Japanese Patent Laid-Open No. 54-129064 JP 59-62115 A JP-A-62-286720 JP-A-60-207329 JP 58-69252 A JP-A-55-62605 JP 2000-501549 Gazette JP 2000-294447 A Japanese Patent Laid-Open No. 4-160705 JP-A-2-206623

  An object of the present invention is to provide a high dielectric film that is highly dielectric and can be thinned, has excellent winding properties (flexibility), and has low dielectric loss.

  The present inventors use composite oxide particles containing at least three metal elements selected from the group consisting of Group 2 metal elements and Group 4 metal elements in the periodic table as oxide particles for obtaining a high dielectric constant. Thus, the inventors have found that the above-described problems can be solved, and have arrived at the present invention.

That is, the present invention
(A) Vinylidene fluoride polymer (hereinafter also referred to as “VdF polymer (A)”) and (B) at least three metals selected from the group consisting of Group 2 metal elements and Group 4 metal elements of the periodic table Complex oxide particles containing elements (hereinafter also referred to as “composite oxide particles (B)”)
And a high dielectric film containing 10 to 500 parts by mass of the composite oxide particles (B) with respect to 100 parts by mass of the vinylidene fluoride polymer (A).

  The relative dielectric constant of the vinylidene fluoride polymer (A) itself at 1 kHz and 25 ° C. is preferably 5-15.

  The composite oxide particles (B) are preferably particles of barium zirconate titanate or strontium zirconate titanate.

  The composite oxide particles (B) preferably have an average particle size of 0.01 to 2 μm.

  The high dielectric film preferably has a relative dielectric constant of 20 to 80 at 1 kHz and 25 ° C., a dielectric loss of 0.2 to 6%, and a film thickness of 3 to 9 μm.

  The high dielectric film is preferably a film for a film capacitor.

  The present invention also relates to a laminated film for a film capacitor in which an electrode layer is laminated on at least one surface of the high dielectric film.

  Moreover, this invention relates to the film capacitor formed using the said laminated film for film capacitors.

The present invention also provides:
(A) a vinylidene fluoride polymer,
(B) a composite oxide particle containing at least three metal elements selected from the group consisting of group 2 metal elements and group 4 metal elements of the periodic table;
(C) at least one affinity improver selected from the group consisting of a coupling agent, a surfactant or an epoxy group-containing compound, and (D) a solvent, and a vinylidene fluoride polymer (A) 100 mass 10 to 500 parts by mass of composite oxide particles (B) with respect to parts, and 0.01 to 30 parts by mass of affinity improver (C) with respect to 100 parts by mass of composite oxide particles (B). The present invention relates to a coating composition for forming a dielectric film.

  The dielectric constant of the vinylidene fluoride polymer (A) itself at 1 kHz and 25 ° C. is preferably 5-15.

  The composite oxide particles (B) are preferably particles of barium zirconate titanate or strontium zirconate titanate.

  The composite oxide particles (B) preferably have an average particle size of 0.01 to 2 μm.

  The coating composition is preferably used for forming a high dielectric film for a film capacitor.

  Furthermore, this invention relates to the manufacturing method of the high dielectric film characterized by apply | coating the said coating composition to a base material, and drying.

  According to the present invention, by using composite oxide particles containing at least three kinds of metals selected from the group consisting of Group 2 metals and Group 4 metals, high dielectric properties and thinning are possible, and winding is also possible. It is possible to provide a high dielectric film that is excellent in flexibility (flexibility) and has a small dielectric loss.

  The high dielectric film of the present invention comprises a VdF polymer (A) and composite oxide particles (B), and 10 parts of the composite oxide particles (B) with respect to 100 parts by mass of the VdF polymer (A). Contains ~ 500 parts by weight.

  The VdF polymer (A) may be a homopolymer of vinylidene fluoride (VdF) or a copolymer with another monomer copolymerizable with VdF (hereinafter also referred to as “VdF copolymer”). Further, it may be a blend of a VdF homopolymer and a VdF copolymer, or a blend of VdF copolymers.

Examples of other monomers copolymerizable with VdF include tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), trifluoroethylene (TrFE), monofluoroethylene, hexafluoropropylene (HFP), perfluoro ( Fluorine-containing olefins such as alkyl vinyl ether (PAVE); fluorine-containing acrylates, functional group-containing fluorine-containing monomers, and the like. Of these, TFE, CTFE, and HFP are preferred from the viewpoint of good solvent solubility. As for the copolymerization ratio, it is preferable that VdF is 50 mol% or more, preferably 60 mol% or more from the viewpoint of high dielectric constant and high solvent solubility. In the case of the VdF / TFE copolymer, the composition ratio is such that the VdF unit is 60 to 95 mol% and the TFE unit is 5 to 40 mol%, and in particular, the VdF unit is 70 to 90 mol% and the TFE unit is It is preferable that it is 10-30 mol% from the point that a withstand voltage becomes high. In order to reduce the dielectric loss of the VdF polymer itself, it is also preferable to copolymerize with ethylene, propylene, alkyl vinyl ether, vinyl acetate, vinyl chloride, vinylidene chloride, CH ₂ = CHCF ₃ , CH ₂ = CFCF ₃ or the like. In this case, since it is difficult to react directly with VdF, it can be copolymerized with other copolymerizable monomers such as TFE and CTFE. The relative dielectric constant (1 kHz, 25 ° C.) of the VdF polymer itself is preferably 5 or more, more preferably 6 or more, and particularly preferably 7.5 or more from the viewpoint of further increasing the dielectric constant of the film. The upper limit is not particularly limited, but is usually 15 and preferably 13.

  The composite oxide particles (B) are representative high dielectric inorganic particles containing at least three kinds of metal elements selected from the group consisting of Group 2 metal elements and Group 4 metal elements of the periodic table. The relative dielectric constant at 25 ° C. is 100 or more.

  In the composite oxide (B), specific examples of the Group 2 metal element of the periodic table include, for example, Mg, Ca, Sr, Ba and the like, and specific examples of the Group 4 metal element of the periodic table include, for example, Ti, Zr, Hf and the like can be mentioned.

  In the composite oxide (B), as a preferable combination of three or more selected from Group 2 metal elements and Group 4 metal elements of the periodic table, for example, a combination of Sr, Ba, Ti, a combination of Sr, Ti, Zr, Sr, Ba, Zr combination, Ba, Ti, Zr combination, Sr, Ba, Ti, Zr combination, Mg, Ti, Zr combination, Ca, Ti, Zr combination, Ca, Ba, Ti combination, Ca, Ba, Zr combination, Ca, Ba, Ti, Zr combination, Ca, Sr, Zr combination, Ca, Sr, Ti, Zr combination, Mg, Sr, Zr combination, Mg, Sr, Ti, A combination of Zr, a combination of Mg, Ba, Ti, and Zr, a combination of Mg, Ba, and Zr, and the like can be given.

  Examples of the composite oxide particles (B) include perovskite-type oxides containing at least three kinds selected from the group consisting of the group 2 metal elements and group 4 metal elements described above, and specifically, strontium zirconate titanate. Barium zirconate titanate, barium strontium zirconate titanate, magnesium zirconate titanate, calcium zirconate titanate, barium calcium zirconate titanate and the like. Of these, barium zirconate titanate and strontium zirconate titanate are preferable because of their high dielectric constant and low dielectric loss.

  The average particle size of the composite oxide particles (B) is 0.01 to 2 μm, more preferably 0.01 to 1.0 μm, and particularly 0.01 to 0.7 μm. From the point which is excellent in the property and uniform dispersibility.

  The compounding quantity of composite oxide particle (B) is 10 mass parts or more with respect to 100 mass parts of VdF type | system | group polymer (A), Preferably it is 30 mass parts or more, More preferably, it is 50 mass parts or more. If the amount is too small, the effect of improving the dielectric constant of the film becomes small. The upper limit is 500 parts by mass. If the amount is too large, problems occur in terms of strength as a film and surface roughness. A preferable upper limit is 400 parts by mass, and further 300 parts by mass.

  In addition to other polymers (a), other highly dielectric inorganic particles (b), and affinity improvers (C), the film of the present invention may further contain optional fillers such as reinforcing fillers, antistatic fillers, etc. Additives such as various fillers such as the affinity improver (c) may be included.

  Other polymers (a) include, for example, polycarbonate (PC), polyester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), silicone resin, polyether, polyvinyl acetate, polyethylene, Polypropylene and the like are preferable. In order to increase the strength, poly (meth) acrylate, epoxy resin, polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyamide (PA), polyimide (PI), polyamideimide (PAI), polycarbonate ( PC), polystyrene, polybenzimidazole (PBI), and the like, and from the viewpoint of supplementing high dielectric properties, odd-numbered polyamides, cyano pullulans, copper phthalocyanine-based polymers, and the like. You may mix | blend these other polymers (a) in the range which does not impair the objective of this invention.

  In the present invention, the combination of high dielectric inorganic particles other than the composite oxide particles (B) is not prohibited, and conventionally known high dielectric inorganic particles may be blended.

As such other high dielectric inorganic particles (b), for example, the formula (b1):
M _d Ti _e O _f
(In the formula, M is a Group 2 metal element from the second period to the fifth period of the periodic table; d is 0.9 to 1.1; e is 0.9 to 1.1; f is 2.8 to 3) .2)
Or a composite oxide (b1) represented by formula (b2):
M ¹ _g M ² _h O _i
(Wherein M ¹ is a Group 2 metal element of the periodic table; M ² is a metal element of the fifth period of the periodic table; g is 0.9 to 1.1; h is 0.9 to 1.1; 2.8-3.2)
And a composite oxide (b2) represented by

  In the formula (b1), M is a Group 2 metal element from the second period to the fifth period of the periodic table, and specific examples thereof include Be, Mg, Ca, and Sr.

  Specific examples of the composite oxide (b1) include beryllium titanate, magnesium titanate, calcium titanate, and strontium titanate.

In the formula (b2), M ¹ is a group 2 metal element of the periodic table, and specific examples thereof include Mg, Ca, Sr, Ba and the like. M ² is a metal element in the fifth period of the periodic table, and specific examples thereof include Zr, Nb, In, Sn, Sb, and the like.

  As the composite oxide (b2), specifically, magnesium stannate, calcium stannate, strontium stannate, barium stannate, magnesium antimonate, calcium antimonate, strontium antimonate, barium antimonate, magnesium zirconate, Examples thereof include calcium zirconate, strontium zirconate, barium zirconate, magnesium indium acid, calcium indium acid, strontium indium acid, and barium indium acid.

  In addition, as other high dielectric inorganic particles (b), barium titanate, lead zirconate titanate, lead antimonate, zinc titanate, lead titanate, titanium oxide and the like can also be used.

  Moreover, the complex compound, solid solution, mixture, etc. of said complex oxide can also be illustrated. Among these, when used together with the composite oxide particles (B), the composite oxide (b1) or (b2) is preferable.

  The other high dielectric inorganic particles (b) have an average particle diameter of 0.01 to 2 μm, preferably 0.01 to 1 μm, more preferably 0.01 to 0.7 μm, and particularly 0.01 to 0 μm. It is preferable that the thickness is about 0.5 μm and about 0.01 to 0.2 μm from the viewpoint of excellent surface smoothness and uniform dispersibility of the film.

  These other high dielectric inorganic particles (b) can be blended within a range that does not impair the object of the present invention, and the blending amount is 10 to 500 parts by mass with respect to 100 parts by mass of the VdF polymer (A). It is preferably 30 to 400 parts by mass, more preferably 50 to 300 parts by mass from the viewpoint of the dielectric constant of the film, the strength as the film, and the surface roughness. Further, a high dielectric organic compound such as copper phthalocyanine tetramer may be blended within a range that does not impair the object of the present invention.

  By adding the affinity improver (C), the affinity between the VdF polymer (A) and the composite oxide particles (B) is increased, and the composite oxide particles (B) are uniformly distributed in the VdF polymer. While being dispersed, it plays a role of firmly bonding the composite oxide particles (B) and the VdF-based polymer (A) in the film, thereby suppressing the generation of voids and increasing the dielectric constant. In addition, when other high dielectric inorganic particles (b) are blended, it also serves to increase the affinity between the VdF polymer (A) and the other high dielectric inorganic particles (b).

  As the affinity improver (C), a coupling agent (C1), a surfactant (C2) or an epoxy group-containing compound (C3) is effective.

  Examples of the coupling agent (C1) include titanium coupling agents, silane coupling agents, zirconium coupling agents, zircoaluminate coupling agents, and the like.

  Examples of the titanium coupling agent include monoalkoxy type, chelate type, and coordinate type, and monoalkoxy type and chelate type are preferable from the viewpoint of good affinity with the composite oxide particles (B). . When other high dielectric inorganic particles (b) are blended, the monoalkoxy type and chelate type have good affinity with other high dielectric inorganic particles (b).

  Examples of the silane coupling agent include high molecular types and low molecular types, and monoalkoxysilanes, dialkoxysilanes, trialkoxysilanes, dipodal alkoxysilanes, etc. in terms of the number of functional groups. In particular, a low molecular weight alkoxysilane is preferable from the viewpoint of good affinity with the composite oxide particles (B). When other high dielectric inorganic particles (b) are blended, the low molecular type alkoxysilane has good affinity with other high dielectric inorganic particles (b).

  Examples of the zirconium-based coupling agent include monoalkoxy zirconium and trialkoxy zirconium.

  Examples of the zircoaluminate coupling agent include monoalkoxyzircoaluminate and trialkoxyzircoaluminate.

  As the surfactant (C2), there are a high molecular type and a low molecular type, and there are a nonionic surfactant, an anionic surfactant and a cationic surfactant from the viewpoint of the type of functional group, and these are used. From the viewpoint of good thermal stability, polymer type surfactants are preferred.

  Examples of the nonionic surfactant include polyether derivatives, polyvinyl pyrrolidone derivatives, alcohol derivatives, and the like. In particular, polyether derivatives are preferable from the viewpoint of good affinity with the composite oxide particles (B). . When other high dielectric inorganic particles (b) are blended, the polyether derivative has good affinity with other high dielectric inorganic particles (b).

  Examples of the anionic surfactant include polymers containing sulfonic acid, carboxylic acid, and salts thereof. Specifically, from the viewpoint of good affinity with the VdF-based polymer (A), specifically, Is preferably an acrylic acid derivative polymer, a methacrylic acid derivative polymer, or a maleic anhydride copolymer.

  Examples of the cationic surfactant include compounds having a nitrogen-containing complex ring such as amine compounds and imidazolines, and halogenated salts thereof. From the viewpoint of low aggressiveness to the VdF polymer (A). A compound having a nitrogen-containing complex ring is preferred. Examples of the salt form include ammonium salts containing halogen anions such as alkyltrimethylammonium chloride. An ammonium salt containing a halogen anion is preferable from the viewpoint of a high dielectric constant.

  Examples of the epoxy group-containing compound (C3) include an epoxy compound and a glycidyl compound, which may be a low molecular weight compound or a high molecular weight compound. Among these, a low molecular weight compound having one epoxy group is preferable from the viewpoint of particularly good affinity with the VdF polymer (A). In addition, the epoxy group containing coupling agent (for example, epoxysilane etc.) classified into a coupling agent is not included in an epoxy group containing compound (C3) in this invention, but is included in a coupling agent (C1).

  Preferable examples of the epoxy group-containing compound (C3) are those having the formula (C3):

(In the formula, R may have a hydrogen atom, an oxygen atom, a nitrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms which may contain a carbon-carbon double bond or a substituent. A good aromatic ring; l is 0 or 1; m is 0 or 1; n is an integer of 0 to 10)
The compound shown by these is mention | raise | lifted.

  As a specific example,

And those having a ketone group or an ester group.

  The affinity improver (C) can be blended within a range that does not impair the object of the present invention. Specifically, the blending amount is 0 with respect to 100 parts by mass of the composite oxide particles (B). From 0.01 to 30 parts by mass, more preferably from 0.1 to 25 parts by mass, and particularly from 1 to 20 parts by mass, can be uniformly dispersed, and the resulting film has a high dielectric constant.

  As the affinity improver (C), a coupling agent (C1) and an epoxy group-containing compound (C3) are preferable from the viewpoint of good affinity with the composite oxide particles (B), and in particular, a titanium coupling agent or A silane coupling agent is particularly preferred from the viewpoint of good affinity for both the VdF polymer (A) and the composite oxide particles (B). When other high dielectric inorganic particles (b) are blended, the coupling agent (C1) and the epoxy group-containing compound (C3), particularly the titanium coupling agent and the silane coupling agent, Affinity with other highly dielectric inorganic particles (b) is also good.

  In addition, the coupling agent (C1) and the epoxy group-containing compound (C3) form a chemical bond (having a reactive group) with the composite oxide particle (B), so that the affinity-improving action is further enhanced. Demonstrate. When other high dielectric inorganic particles (b) are blended, the coupling agent (C1) and the epoxy group-containing compound (C3) are also bonded to other high dielectric inorganic particles (b). Form.

  Examples of reinforcing fillers include silicon carbide, silicon nitride, magnesium oxide, potassium titanate, glass, alumina, boron compound particles or fibers, and further as fillers for reducing dielectric loss, For example, calcium oxide, magnesium oxide, alumina, silica, calcium carbonate, magnesium carbonate, bismuth oxide and the like can be mentioned. Examples of other affinity improvers (c) include functional group-modified polyolefin, styrene-modified polyolefin, functional Examples thereof include group-modified polystyrene, polyacrylic imide, cumylphenol, and the like.

  The high dielectric film of the present invention can be produced by either the melt-kneading method (1) or the coating method (2), but is produced by the coating method (2) from the viewpoint of simplicity and excellent uniformity of the film obtained. It is advantageous to do so.

When a high dielectric film is produced by a coating method, first, a coating composition is prepared. The coating composition of the present invention comprises
(A) VdF polymer,
(B) Composite oxide particles containing at least three metals selected from the group consisting of Group 2 metals and Group 4 metals,
(C) at least one affinity improver selected from the group consisting of a coupling agent, a surfactant or an epoxy group-containing compound, and (D) a solvent, and a vinylidene fluoride polymer (A) 100 mass 10 to 500 parts by mass of composite oxide particles (B) and 0.01 to 30 parts by mass of affinity improver (C) for 100 parts by mass of composite oxide particles (B) A composition.

  Regarding the specific examples and blending amounts of the VdF polymer (A), the composite oxide particles (B), the affinity improver (C), and other optional components, the above description is applied as it is.

  The coating composition is preferably adjusted with a solvent (D) so that the viscosity is 0.01 to 3 Pa · s from the viewpoint of good coating properties and a uniform and smooth film. In particular, it is preferably 1.5 Pa · s or less from the viewpoint of suppressing the surface roughness.

  The form of the coating composition may be an emulsion type (the solvent is water or the like). In this case, the VdF-based polymer (A) is also a particle, and a particle-particle mixed system with the composite oxide particle (B). Since uniform dispersion is difficult, the VdF polymer (A) is made into an organic solvent solution, and the composite oxide particles (B) are dispersed in the solution. It is preferable because it is easily obtained.

  Examples of the solvent (D) for dissolving the VdF polymer (A) include amide solvents such as N, N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and N, N-dimethylacetamide (DMAc). Ketone solvents such as cyclohexane, methyl isobutyl ketone (MIBK) and 2-heptanone (MAK); ester solvents such as butyl acetate and ethyl lactate; ether solvents such as ethyl cellosolve and methyl cellosolve; propylene carbonate and diethylene carbonate ( Carbonate type solvents such as DEC) are preferable, and amide type solvents are preferable from the viewpoint of particularly excellent solubility of the VdF type polymer (A). These solvents may be used alone or in combination. In particular, an amide solvent is the main solvent, and an ester, ketone, ether, or carbonate solvent mixed with it as a cosolvent is suitable for producing uniform thin films with few pinholes because of its good wettability to the substrate. It is. In particular, from the viewpoint of increasing the solubility of the VdF-based polymer (A), it is preferable to adjust the solvent so that the relative dielectric constant of the solvent at 1 kHz and 25 ° C. is 22 or more, and to improve the coatability. From this point of view, it is preferable to adjust the solvent so that the surface tension of the solvent is 35 dyn / cm or less.

  In the coating composition, in addition to the solvent (D), a component that does not exist in the film (disappears during film formation) or the effect that the film of the present invention has even if it exists (high dielectric constant, flexibility) Anti-foaming agent, dispersing agent, wetting agent, leveling agent, spreading agent and the like may be added as a component that does not substantially affect the property, thinness, and low dielectric loss.

  The coating composition is prepared by preparing a solution of the solvent (D) of the VdF polymer (A), then adding the remaining components as appropriate, and forcibly stirring and dispersing them. More specifically, there are the following methods.

(1) The composite oxide particles (B) and the affinity improver (C) are mixed with the solvent (D) in advance and stirred and dispersed, and the resulting dispersion mixture and the VdF polymer (A) solution are sufficiently stirred. Dispersion method:
In this method, when the affinity improver (C) is a coupling agent (C1) or an epoxy group-containing compound (C3) which is a chemically reactive affinity improver, the affinity improver (C) and the composite oxidation are combined. After reacting the product particles (B), the mixture may be dispersed with forced stirring, or the composite oxide particles (B) and the affinity improver (C) may be added to the solvent (D) for reaction and forced stirring dispersion. You may carry out simultaneously and you may use both together. When the affinity improver (C) is the surfactant (C2), no reaction occurs, so the composite oxide particles (B) and the affinity improver (C) are added to the solvent (D). It is convenient to carry out the reaction and the forced stirring dispersion at the same time.

  Further, in order to increase the stability of the dispersion mixture of the composite oxide particles (B) and the affinity improver (C), VdF during forced stirring and dispersion of the composite oxide particles (B) and the affinity improver (C). It is desirable that a small amount of the system polymer (A) solution coexists.

(2) A method of forcibly stirring and dispersing by adding the composite oxide particles (B) and the affinity improver (C) to the solvent (D) solution of the VdF polymer (A) all at once or sequentially:
When adding sequentially, the order of addition is not particularly limited, and forced stirring and dispersing treatment may be performed each time one component is added.

  In any of the above methods (1) and (2), it is desirable to remove the adsorbed water on the surface of the composite oxide particles (B) in advance by heat treatment or the like because the uniform dispersibility is further improved. By subjecting the composite oxide particles (B) to a preliminary heat treatment or surface treatment, uniform dispersion is facilitated even if the composite oxide particles (B) have a large average particle diameter. Preferably, it is desirable to perform both preliminary heat treatment and surface treatment.

  Each component may be added in a predetermined amount at once, or may be added in divided portions. When further divided and added, for example, a part of the VdF-based polymer (A) is added at the time of mixing the composite oxide particles (B) and the affinity improver (C), and the remaining VdF-based is mixed after mixing. The order of addition and divided addition may be freely combined such that the polymer (A) is added and the affinity improver (C) is additionally added and mixed.

  The important point here is to perform sufficient forced stirring and dispersion. If this dispersion treatment is insufficient, solid components such as composite oxide particles (B) will settle easily, making the coating itself difficult, or causing phase separation inside when the coating film is dried. In some cases, it may be impossible to form a film having uniform, excellent mechanical characteristics and uniform dielectric characteristics. In addition, you may perform this forced stirring dispersion | distribution process just before coating with respect to the once prepared composition.

  The standard for forced stirring and dispersion is that the coating composition after stirring and dispersion does not cause phase separation even after standing at room temperature (25 ° C.) for 7 days (change in solution turbidity is slight (less than 10%)). It can be set by conducting a preliminary experiment.

  Preferred examples of the forced stirring and dispersing apparatus include a ball mill, a sand mill, an atlite, a visco mill, a roll mill, a Banbury mixer, a stone mill, a vibrator mill, a dispersin mill, a disk impeller, a jet mill, and a dino mill. Among these, a jet mill, a roll mill, and a dyno mill are preferable from the viewpoint that impurities hardly enter and continuous production is possible.

Non-limiting forced stirring and dispersing conditions include, for example, the following ranges.
Equipment: Sand mill stirring conditions:
Stirring speed: 100 to 10,000 rpm
Stirring time: 5 to 120 minutes Others: Add zirconia beads.

  A film is formed from the obtained uniform coating composition. The film is preferably formed by coating the substrate, drying it, and peeling it from the substrate, if necessary, in terms of easy operation, simple equipment, and easy control of the film thickness. In addition, the film may be formed by a method such as the Langmuir Blodget method or the impregnation method.

  As coating methods, knife coating method, cast coating method, roll coating method, gravure coating method, blade coating method, rod coating method, air doctor coating method, curtain coating method, fakunrun coating method, kiss coating method, screen coating Method, spin coating method, spray coating method, extrusion coating method, electrodeposition coating method, etc., among these, rolls are easy to operate, have little film thickness variation, and are excellent in productivity. A coating method, a gravure coating method, and a cast coating method are preferable.

  Drying can be performed by a method using Yankee cylinder, counter flow, hot air injection, air flow cylinder, air through, infrared ray, microwave, induction heating and the like. For example, in the hot air injection method, a condition of 130 to 200 ° C. and within 1 minute can be suitably employed.

  The high dielectric film of the present invention may be left on the substrate as a so-called coating. However, when the film is used for a film capacitor or the like, it is peeled off from the substrate to form a single film. A material from which the polymer (A) is easily peeled, for example, a metal plate such as stainless steel or copper; a glass plate; a polymer film on which ITO or ZnO is deposited; a polymer film excellent in releasability is preferable. Examples of the polymer film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), and polyphenylene sulfide. Engineering plastics such as (PPS), polyphenylene oxide (PPO), and polysulfone (PSF) are suitable.

  When the film is left on the substrate, the coating composition of the present invention can be applied onto a polymer film and dried to form a laminated film. As the substrate for the laminated film, a polymer film having a film thickness of about 1.5 to 3 μm, which has good adhesion with the VdF polymer (A), is preferable. As the polymer, engineering plastics such as PET, PEN, PC, PA, PI, PAI, PBI, PPS, PPO, and PSF are suitable.

  The single film may be used as it is, but may be further stretched by a conventional method. In that case, the stretch ratio is preferably about 2 to 6 times.

  In addition, either a single film or a laminated film may be further surface-treated with another polymer in order to facilitate the deposition of aluminum for electrodes, or the surface of the film may be subjected to plasma treatment or corona discharge treatment. Further, another type of polymer may be surface-coated in order to suppress surface roughness of the film, or a crosslinking treatment with ultraviolet rays, electron beams, or radiation may be performed to improve the strength. Furthermore, the film may be pressed, for example, roll pressed, in which case the surface smoothness of the film is improved.

  The high dielectric film of the present invention thus obtained can have a film thickness of 9 μm or less, preferably 6 μm or less, and more preferably 5 μm or less. The lower limit of the film thickness is 3 μm from the viewpoint of maintaining mechanical strength, although it varies depending on the type of polymer and the particle diameter and blending amount of the composite oxide particles (B). The high dielectric film of the present invention can have a relative dielectric constant of 20 or more and a dielectric loss of 6% or less at 1 kHz and 25 ° C. The upper limit of the relative dielectric constant varies depending on the type of polymer and the particle diameter and blending amount of the composite oxide particles (B), but is usually about 80. The lower limit of the dielectric loss varies depending on the type of polymer and the particle diameter and blending amount of the composite oxide particles (B), but is usually about 0.2%.

In the high dielectric film of the present invention, the film thickness can be reduced despite the relatively high filling rate (10% by mass or more) of the composite oxide particles (B), so that the capacitance is increased. be able to. For example, when the barium zirconate titanate particles having a relative dielectric constant of 2000 are composite oxide particles (B) and the filling rate is 100% by mass, the relative dielectric constant of the film at 1 kHz and 25 ° C. may be 30 or more. it can. In this case, if the area of the circular electrode is 9.5 mm ² , the capacitance is 2.8 nF or more when the film thickness is 9 μm, and the capacitance is 4.2 nF or more when the film thickness is 6 μm.

  Further, according to the film of the present invention, when the coupling agent (C1) or the epoxy group-containing compound (C3) is blended, the composite oxide particles (B) and the VdF-based polymer (A) are produced by the function. A dense structure is achieved that is tightly bonded and has a low void content (for example, 5% by volume or less, preferably 1% by volume or less), and can increase the withstand voltage.

  Despite being dense, the film of the present invention is excellent in flexibility (winding property). For example, when the film thickness is 5 μm, no cracks or creases occur in the folds in the 180-degree bending test. Therefore, when used for a film capacitor, workability (winding property and followability) is remarkably improved.

  Further, the film of the present invention is excellent in surface smoothness, and for example, the surface center roughness can be ± 1 μm or less, and further ± 0.6 μm or less. By being excellent in surface smoothness, homogenization of electrical characteristics is improved.

  When the high dielectric film of the present invention is used as, for example, a film for a film capacitor, a laminated film can be formed on the surface by an evaporation method or the like on the surface, and a film capacitor can be formed using the laminated film. A conventionally well-known thing can be employ | adopted for materials, formation methods, conditions, etc. of an electrode.

  The high dielectric film of the present invention is particularly useful as a film for a film capacitor, but in addition, as a film for a piezoelectric element, a film for a pyroelectric material, a dielectric film for carrying a transfer body, a film for a ferroelectric element, etc. Is also useful.

  Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to such examples.

  The characteristic values used in this specification are measured by the following method.

(Relative permittivity, dielectric loss)
A polymer / inorganic fine particle mixed film formed on a metal substrate or an aluminum vapor deposited polymer / inorganic fine particle mixed film in which aluminum is vapor-deposited on one side. Aluminum was vapor-deposited with an area of 95 mm ² to prepare a sample. This sample is measured for impedance and dielectric loss at frequencies of 100 Hz, 1 kHz, and 10 kHz at room temperature (25 ° C.) and 100 ° C. using an impedance analyzer (HP4194A manufactured by Hewlett-Packard Company).

(Film thickness)
Using a digital length measuring instrument Digimicro (MF-1001 manufactured by Nikon Corporation), the film placed on the substrate is measured at room temperature.

(Flexibility)
A film having a length of 20 mm, a width of 5 mm, and a thickness of 5 μm is bent at 180 degrees, and then cracks and deformation of the bent portion are observed with the naked eye. The case where there is no crack or deformation in the bent part is marked with ◯.

Example 1
In a 3 L separable flask, 800 parts by mass of N, N-dimethylacetamide (DMAc) (manufactured by Kishida Chemical Co., Ltd.) and vinylidene fluoride (VdF) homopolymer (KAYNAR761 manufactured by ARKEMA), relative permittivity 9.6 (1 kHz , 25 ° C.)) 200 parts by mass was added and stirred with a mechanical stirrer at 80 ° C. for 3 hours to obtain a 20% by mass polymer solution. This polymer solution was a transparent homogeneous solution.

  100 parts by mass of barium zirconate titanate (BTZ) having an average particle size of 0.1 μm (BTZ-01-9010 manufactured by Sakai Chemical Industry Co., Ltd.), 60 parts by mass of DMAc, 40 parts by mass of methyl isobutyl ketone (MIBK), As a titanium coupling agent, 5 parts by mass of Prenact KR-55 manufactured by Ajinomoto Fine Techno Co., Ltd. was added.

  The same amount of zirconia beads having a diameter of 1 mm was added to this mixture and placed in a desktop planetary ball mill (Planet M manufactured by Gokin Planetaring) and dispersed at room temperature for 15 minutes at a rotation speed of 800 rpm. . The mixture after the dispersion treatment was passed through a stainless steel mesh (80 mesh manufactured by Manabe Kogyo Co., Ltd.) to remove zirconia beads to obtain a composite oxide dispersion solution.

  34 parts by mass of this dispersion (containing 16.6 parts by mass of barium zirconate titanate, 0.83 parts by mass of titanium coupling agent, 10.0 parts by mass of DMAc, and 6.63 parts by mass of MIBK) and 50 DMAc solutions of VdF homopolymer Mass parts (containing 10.0 parts by mass of VdF homopolymer and 40.0 parts by mass of DMAc) and 26.7 parts by mass of MIBK were mixed to prepare a coating composition of the present invention.

  Subsequently, the obtained composition was applied onto an aluminum substrate with a bar coater and dried with hot air at 180 ° C. for 1 minute to form a dielectric film having a thickness of about 5.0 μm.

  The obtained film was examined for relative dielectric constant, dielectric loss and flexibility at each frequency. The results are shown in Table 1.

Example 2
The same as in Example 1 except that the type of the composite oxide particles (B) was changed to barium calcium zirconate titanate (BCTZ) (BCTZF3 manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle size of 0.75 μm. The coating composition of the invention was prepared, and then a dielectric film having a thickness of about 5.0 μm was formed in the same manner as in Example 1, and the relative dielectric constant, dielectric loss and flexibility at each frequency were examined. The results are shown in Table 1.

Comparative Example 1
The type of the composite oxide particles (B) was changed to lead zirconate titanate (PZT) (PZT-HQ manufactured by Sakai Chemical Industry Co., Ltd.) having an average particle size of 1.0 μm in the same manner as in Example 1. A coating composition of the present invention was prepared, and then a dielectric film having a thickness of 5.0 μm was formed in the same manner as in Example 1, and the relative dielectric constant, dielectric loss and flexibility at each frequency were examined. The results are shown in Table 1.

Comparative Example 2
The coating composition of the present invention was the same as in Example 1 except that the type of the composite oxide particles (B) was changed to barium titanate (BT-01 manufactured by Sakai Chemical Industry Co., Ltd.) having an average particle size of 0.1 μm. Then, a dielectric film having a thickness of 5.0 μm was formed in the same manner as in Example 1, and the relative dielectric constant, dielectric loss and flexibility at each frequency were examined. The results are shown in Table 1.

Example 3
As composite oxide particles (B), BTZ having an average particle diameter of 0.1 μm (BTZ-01-9010 manufactured by Sakai Chemical Industry Co., Ltd.) is not 100 parts by mass, and BTZ having an average particle diameter of 0.1 μm (Sakai Chemical). Example 1 except that 50 parts by mass of BTZ-01-9010 manufactured by Kogyo Co., Ltd. and calcium titanate (CT) having an average particle size of 1.0 μm (CTG manufactured by Nippon Chemical Industry Co., Ltd.) were added. Similarly, a coating composition of the present invention was prepared, and then a dielectric film having a thickness of 5.0 μm was formed in the same manner as in Example 1, and the relative dielectric constant, dielectric loss, and flexibility at each frequency were adjusted. Examined. The results are shown in Table 2.

Example 4
As composite oxide particles (B), BTZ having an average particle diameter of 0.1 μm (BTZ-01-9010 manufactured by Sakai Chemical Industry Co., Ltd.) is not 100 parts by mass, and BTZ having an average particle diameter of 0.1 μm (Sakai Chemical). Example 1 except that 50 parts by mass of BTZ-01-9010 manufactured by Kogyo Co., Ltd. and calcium zirconate (CZ) having an average particle size of 0.7 μm (CZ-TH manufactured by Kyoritsu Material Co., Ltd.) were added. The coating composition of the present invention was prepared in the same manner as described above, and then a dielectric film having a thickness of 5.0 μm was formed in the same manner as in Example 1 to obtain the relative dielectric constant, dielectric loss and flexibility at each frequency. I investigated. The results are shown in Table 2.

Example 5
As composite oxide particles (B), BTZ (BTZ-01-9010 manufactured by Sakai Chemical Industry Co., Ltd.) with an average particle size of 0.1 μm is not 100 parts by mass, but BCTZ (Nippon Chemical Co., Ltd.) with an average particle size of 0.75 μm. In the same manner as in Example 1, except that 50 parts by mass of BCTZF3 manufactured by Kogyo Co., Ltd. and calcium stannate (CS) having an average particle size of 6.0 μm (CS manufactured by Kyoritsu Material Co., Ltd.) were added. Then, a dielectric film having a thickness of 7.5 μm was formed in the same manner as in Example 1, and the relative dielectric constant, dielectric loss and flexibility at each frequency were examined. The results are shown in Table 2.

Claims (14)

(A) a vinylidene fluoride polymer, and (B) a composite oxide particle containing at least three metal elements selected from the group consisting of a group 2 metal element and a group 4 metal element of the periodic table. A high dielectric film containing 10 to 500 parts by mass of the composite oxide particles (B) with respect to 100 parts by mass of the vinylidene polymer (A). The high dielectric film according to claim 1, wherein the relative dielectric constant of the vinylidene fluoride polymer (A) itself at 1 kHz and 25 ° C is 5 to 15. The high dielectric film according to claim 1 or 2, wherein the composite oxide particles (B) are particles of barium zirconate titanate or strontium zirconate titanate. The high dielectric film according to any one of claims 1 to 3, wherein the composite oxide particles (B) have an average particle diameter of 0.01 to 2 µm. 5. The high dielectric film according to claim 1, wherein the relative dielectric constant at 1 kHz and 25 ° C. is 20 to 80, the dielectric loss is 0.2 to 6%, and the film thickness is 3 to 9 μm. The high dielectric film according to claim 1, which is a film for a film capacitor. The laminated film for film capacitors by which an electrode layer is laminated | stacked on the at least single side | surface of the high dielectric film in any one of Claims 1-6. A film capacitor comprising the laminated film for a film capacitor according to claim 7. (A) a vinylidene fluoride polymer,
(B) a composite oxide particle containing at least three metal elements selected from the group consisting of group 2 metal elements and group 4 metal elements of the periodic table;
(C) at least one affinity improver selected from the group consisting of a coupling agent, a surfactant or an epoxy group-containing compound, and (D) a solvent, and a vinylidene fluoride polymer (A) 100 mass 10 to 500 parts by mass of composite oxide particles (B) with respect to parts, and 0.01 to 30 parts by mass of affinity improver (C) with respect to 100 parts by mass of composite oxide particles (B). A coating composition for forming a dielectric film. The coating composition according to claim 9, wherein the relative dielectric constant of the vinylidene fluoride polymer (A) itself at 1 kHz and 25 ° C is 5 to 15. The coating composition according to claim 9 or 10, wherein the composite oxide particles (B) are particles of barium zirconate titanate or strontium zirconate titanate. The coating composition according to claim 9, wherein the composite oxide particles (B) have an average particle size of 0.01 to 2 μm. The coating composition according to claim 9, which is used for forming a high dielectric film for a film capacitor. A method for producing a high dielectric film, wherein the coating composition according to claim 9 is applied to a substrate and dried.