Polymer material for piezoelectric device

Abstract

To solve the problem in which: the addition of high-dielectric fillers is undesirable in providing a flexible and soft material for use in piezoelectric devices; and there is a demand for responsiveness without relying on excessive voltage in voltage-driving polymer materials.SOLUTION: The above problem can be solved by using a polymer material for a piezoelectric device, which contains a polyether-based polymer with a polyoxyethylene backbone in its main chain and has a storage elastic modulus E' of 1.5 MPa or less at 23°C and 1 Hz in dynamic viscoelasticity measurement (tensile mode).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer material for a piezoelectric device containing a polyether polymer, and to piezoelectric devices such as piezoelectric device elements, sensors, and actuators. [Background technology]

[0002] Polyether polymers can be made into polymers with a variety of properties by selecting the type of oxirane compound used as the raw material. Therefore, they are used in a wide range of fields, such as automotive rubber parts, rubber components for electrical and electronic devices, rubber materials for civil engineering and construction, various industrial rubber components, polymers for various plastic blends, and polymer solid electrolytes.

[0003] Furthermore, polyether polymers, epichlorohydrin homopolymers, epichlorohydrin-ethylene oxide copolymers, and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymers, which are generally referred to as epichlorohydrin-based rubbers, have excellent heat resistance, oil resistance, fuel resistance, ozone resistance, low-temperature properties, semiconductivity, and the like, and are therefore widely used as rubber parts for automobiles and rubber members for electrical and electronic devices.

[0004] On the other hand, dielectric elastomer materials, which convert electricity into force, are useful as materials for actuators, sensors, etc. Dielectric constant is one of the important properties for elastomers to obtain large displacements and forces, and increasing the dielectric constant of elastomer materials is required to improve the performance of devices using dielectric elastomers.

[0005] For example, in Patent Document 1, a high dielectric constant is achieved by kneading a high dielectric filler into rubber, but this is not preferable for a dielectric elastomer, which requires high rubber hardness and softness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-291206 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to provide flexible and soft materials for piezoelectric devices, the addition of high-dielectric fillers is not desirable. Also, when voltage-driving polymer materials, they are required to respond without using excessive voltage, which is a challenge. [Means for solving the problem]

[0008] As a result of extensive research into the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by using a polymer material for a piezoelectric device that contains a polyether-based polymer whose main chain has a polyoxyethylene skeleton, and that has a storage modulus E' of 1.5 MPa or less at 23°C and a frequency of 1 Hz as measured in dynamic viscoelasticity measurement (tensile mode).

[0009] The present invention can also be described as follows. Item 1: A polymer material for piezoelectric devices that contains a polyether polymer whose main chain is made of a polyoxyethylene skeleton, and has a storage modulus E' of 1.5 MPa or less at 23°C and a frequency of 1 Hz in dynamic viscoelasticity measurement (tensile mode). Item 2: A polymer material for piezoelectric devices containing a polyether polymer whose main chain has a polyoxyethylene skeleton and a plasticizer. Item 3. The polymer material for a piezoelectric device according to Item 2, wherein the plasticizer has an ether skeleton. Item 4. The polymer material for a piezoelectric device according to Item 1, wherein the polyether polymer having a main chain formed of a polyoxyethylene skeleton contains at least one structural unit derived from a compound selected from epihalohydrins, alkylene oxides, and glycidyls. Item 5. An element for a piezoelectric device, using the polymer material for a piezoelectric device according to any one of items 1 to 4. Item 6. A piezoelectric device comprising the piezoelectric device element according to Item 5. Item 7. The piezoelectric device according to Item 6, which is a sensor or an actuator. [Effects of the Invention]

[0010] The polyether polymer of the present invention, whose main chain comprises a polyoxyethylene skeleton, is flexible and is very useful as a polymer material for piezoelectric devices such as sensors or actuators. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. The polymer material for a piezoelectric device of the present invention has a polyether polymer whose main chain comprises a polyoxyethylene skeleton, and has a storage modulus E' of 1.5 MPa or less at 23°C and a frequency of 1 Hz in dynamic viscoelasticity measurement (tensile mode). Although not limited to the mechanism of the present invention, it is believed that the polymer material for a piezoelectric device of the present invention contains a polyether polymer whose main chain comprises a polyoxyethylene skeleton, and has a specific storage modulus E' in dynamic viscoelasticity measurement, which makes it more likely to generate strain in response to stress when an electric field is applied, resulting in a response without the use of an excessive voltage.

[0012] In this specification, numerical values ​​connected with "~" mean a numerical range that includes the numerical values ​​before and after "~" as the lower and upper limits. When multiple lower limits and multiple upper limits are listed separately, any lower limit and upper limit can be selected and connected with "~".

[0013] The polymer material for a piezoelectric device of the present invention has a storage modulus E' of 1.5 MPa or less, preferably 1.4 MPa or less, and particularly preferably 1.3 MPa or less, at 23°C and a frequency of 1 Hz, as measured by dynamic viscoelasticity measurement (tensile mode). The lower limit is not particularly limited, but may be 0.5 MPa or more, or 0.7 MPa or more.

[0014] The polyether polymer having a main chain composed of a polyoxyethylene skeleton is preferably a polymer obtained by polymerizing a compound selected from alkylene oxides such as ethylene oxide, propylene oxide, and n-butylene oxide; glycidyls such as methyl glycidyl ether, ethyl glycidyl ether, 1-butoxy-2,3-epoxypropane (n-butyl glycidyl ether), allyl glycidyl ether, and 1,2-epoxy-3-phenoxypropane (phenyl glycidyl ether); epihalohydrins such as epichlorohydrin and epibromohydrin; and styrene oxide, and more preferably a polymer obtained by polymerizing a compound selected from ethylene oxide, propylene oxide, epichlorohydrin, and allyl glycidyl ether.

[0015] The polyether polymer having a main chain composed of a polyoxyethylene skeleton preferably contains at least one structural unit derived from a compound selected from epihalohydrins, alkylene oxides, and glycidyls. When the polyether polymer having a main chain composed of a polyoxyethylene skeleton is a copolymer, the molar ratio of each structural unit is 1 It is determined by H-NMR spectroscopy.

[0016] The polyether polymer having a main chain composed of a polyoxyethylene skeleton preferably has at least one structural unit derived from a compound selected from epihalohydrins and glycidyls.

[0017] Polyether polymers whose main chains are composed of a polyoxyethylene skeleton preferably contain 0 to 100 mol %, more preferably 10 to 100 mol %, even more preferably 25 to 100 mol %, and particularly preferably 45 to 100 mol % of structural units derived from epihalohydrins. The structural units derived from epihalohydrins may be composed of structural units derived from one type of monomer, or may be composed of structural units derived from two or more types of monomers.

[0018] The polyether polymer having a main chain composed of a polyoxyethylene skeleton preferably contains 0 to 100 mol %, more preferably 0 to 90 mol %, further preferably 0 to 75 mol %, and particularly preferably 0 to 55 mol % of structural units derived from alkylene oxides. The structural units derived from alkylene oxides may be composed of structural units derived from one type of monomer, or may be composed of structural units derived from two or more types of monomers.

[0019] Polyether polymers whose main chains are composed of a polyoxyethylene skeleton preferably contain 0 to 15 mol %, more preferably 1 to 10 mol %, and particularly preferably 2 to 7 mol % of structural units derived from glycidyls. The structural units derived from glycidyls may be composed of structural units derived from one type of monomer, or may be composed of structural units derived from two or more types of monomers.

[0020] In a polyether polymer having a main chain composed of a polyoxyethylene skeleton, when all structural units are taken as 100 mol %, the total of structural units derived from epihalohydrins and structural units derived from alkylene oxides is preferably 85 to 100 mol %, more preferably 90 to 100 mol %, and may be 100 mol %.

[0021] In a polyether polymer having a main chain composed of a polyoxyethylene skeleton, when all structural units are taken as 100 mol %, the total of structural units derived from epihalohydrins, structural units derived from alkylene oxides, and structural units derived from glycidyls is preferably 85 to 100 mol %, more preferably 90 to 100 mol %, and may be 100 mol %.

[0022] Specific examples of polyether polymers whose main chains are composed of a polyoxyethylene skeleton include epichlorohydrin homopolymers, epichlorohydrin-ethylene oxide copolymers, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymers, epichlorohydrin-allyl glycidyl ether copolymers, and ethylene oxide-propylene oxide-allyl glycidyl ether copolymers.

[0023] The molecular weight of the polyether polymer having a main chain composed of a polyoxyethylene skeleton is not particularly limited, but it is generally preferred that the polymer has a Mooney viscosity of ML1+4(100° C.)=30 to 150 or so.

[0024] The weight-average molecular weight of the polymer is preferably 100,000 or more, more preferably 200,000 or more, and more preferably 300,000 or more, and although the upper limit is not particularly limited, it is preferably 3,000,000 or less, and may be 2,000,000 or less. The weight-average molecular weight is calculated by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent in terms of standard polystyrene.

[0025] The polyether polymer can be produced by polymerizing a monomer using a catalyst capable of ring-opening polymerization of an oxirane compound. The polymerization temperature is, for example, in the range of -20 to 100°C. This polymerization may be either solution polymerization or slurry polymerization. Examples of the catalyst include a catalyst system in which an organoaluminum-based compound is reacted with water, a phosphorus oxoacid compound, acetylacetone, or the like, a catalyst system in which an organozinc-based compound is reacted with water, and an organotin-phosphate ester condensate catalyst system.

[0026] The amount of polyether polymer in the polymer material for piezoelectric devices (100% by mass) is preferably 10% by mass or more as a lower limit, preferably 20% by mass or more, or may be 30% by mass or more, 40% by mass or more, or may be 50% by mass or more as a lower limit, and is preferably 99.9% by mass or less, preferably 95% by mass or less, preferably 90% by mass or less, or may be 80% by mass or less as an upper limit.

[0027] The polyether polymer having a main chain composed of a polyoxyethylene skeleton may be crosslinked, and is preferably a crosslinked product.

[0028] The method for crosslinking a polyether polymer having a main chain made of a polyoxyethylene skeleton is not particularly limited, but a crosslinked product obtained by crosslinking a polyether polymer having a main chain made of a polyoxyethylene skeleton with a crosslinking agent is preferred.

[0029] Examples of the crosslinking agent include a crosslinking agent that utilizes the reactivity of chlorine atoms and a crosslinking agent that utilizes the reactivity of side chain double bonds, and examples of the crosslinking agent that utilizes the reactivity of chlorine atoms include polyamine-based crosslinking agents, thiourea-based crosslinking agents, thiadiazole-based crosslinking agents, mercaptotriazine-based crosslinking agents, pyrazine-based crosslinking agents, quinoxaline-based crosslinking agents, bisphenol-based crosslinking agents, etc. Examples of the crosslinking agent that utilizes the reactivity of side chain double bonds include sulfur-based crosslinking agents and organic oxide-based crosslinking agents, and organic oxide-based crosslinking agents are preferred.

[0030] Examples of polyamine crosslinking agents include ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenetetramine, p-phenylenediamine, cumenediamine, N,N'-dicinnamylidene-1,6-hexanediamine, ethylenediamine carbamate, and hexamethylenediamine carbamate.

[0031] Examples of the thiourea-based crosslinking agent include ethylene thiourea, 1,3-diethyl thiourea, 1,3-dibutyl thiourea, and trimethyl thiourea.

[0032] Examples of the thiadiazole crosslinking agent include 2,5-dimercapto-1,3,4-thiadiazole, and 2-mercapto-1,3,4-thiadiazole-5-thiobenzoate.

[0033] Examples of mercaptotriazine crosslinking agents include 2,4,6-trimercapto-1,3,5-triazine, 2-methoxy-4,6-dimercaptotriazine, 2-hexylamino-4,6-dimercaptotriazine, 2-diethylamino-4,6-dimercaptotriazine, 2-cyclohexaneamino-4,6-dimercaptotriazine, 2-dibutylamino-4,6-dimercaptotriazine, 2-anilino-4,6-dimercaptotriazine, and 2-phenylamino-4,6-dimercaptotriazine.

[0034] Examples of pyrazine-based crosslinking agents include 2,3-dimercaptopyrazine derivatives, and examples of 2,3-dimercaptopyrazine derivatives include pyrazine-2,3-dithiocarbonate, 5-methyl-2,3-dimercaptopyrazine, 5-ethylpyrazine-2,3-dithiocarbonate, 5,6-dimethyl-2,3-dimercaptopyrazine, and 5,6-dimethylpyrazine-2,3-dithiocarbonate.

[0035] Examples of quinoxaline-based crosslinking agents include 2,3-dimercaptoquinoxaline derivatives, and examples of 2,3-dimercaptoquinoxaline derivatives include quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 6-ethyl-2,3-dimercaptoquinoxaline, 6-isopropylquinoxaline-2,3-dithiocarbonate, and 5,8-dimethylquinoxaline-2,3-dithiocarbonate.

[0036] Examples of bisphenol-based crosslinking agents include 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfone (bisphenol S), 1,1-cyclohexylidene-bis(4-hydroxybenzene), 2-chloro-1,4-cyclohexylene-bis(4-hydroxybenzene), 2,2-isopropylidene-bis(4-hydroxybenzene) (bisphenol A), hexafluoroisopropylidene-bis(4-hydroxybenzene) (bisphenol AF), and 2-fluoro-1,4-phenylene-bis(4-hydroxybenzene).

[0037] Examples of sulfur-based crosslinking agents include sulfur, morpholine disulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, dipentanemethylene thiuram tetrasulfide, dipentamethylene thiuram tetrasulfide, and dipentamethylene thiuram hexasulfide.

[0038] Examples of organic oxide crosslinking agents include tert-butyl hydroperoxide, p-menthane hydroperoxide, dicumyl peroxide, tert-butyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, benzoyl peroxide, and tert-butyl peroxybenzoate.

[0039] The amount of the crosslinking agent used is preferably 0.03 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the polyether polymer whose main chain is composed of a polyoxyethylene skeleton.

[0040] When crosslinking, a known accelerator (i.e., a crosslinking accelerator) can be used together with the crosslinking agent.

[0041] Examples of the crosslinking accelerator include thiuram-based crosslinking accelerators, thiazole-based crosslinking accelerators, morpholine sulfide-based crosslinking accelerators, sulfenamide-based crosslinking accelerators, guanidine-based crosslinking accelerators, thiourea-based crosslinking accelerators, aldehyde-ammonia-based crosslinking accelerators, dithiocarbamate-based crosslinking accelerators, xanthogenate-based crosslinking accelerators, fatty acid alkali metal salt-based crosslinking accelerators, 1,8-diazabicyclo(5,4,0)undecene-7 (hereinafter abbreviated as DBU) salt-based crosslinking accelerators, and 1,5-diazabicyclo(4,3,0)nonene-5 (hereinafter abbreviated as DBN) salt-based crosslinking accelerators.

[0042] Examples of the thiuram crosslinking accelerator include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide, and tetramethylthiuram monosulfide.

[0043] Thiazole crosslinking accelerators include mercaptobenzothiazole, dibenzothiazyl disulfide, various metal salts of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(N,N-diethylthiocarbamoylthio)benzothiazole, 2-(4'-monofolinodithio)benzothiazole, and di-2-benzothiazolyl disulfide.

[0044] An example of the morpholine sulfide crosslinking accelerator is morpholine disulfide.

[0045] Examples of sulfenamide crosslinking accelerators include N-cyclohexyl-2-benzothiazyl sulfenamide, N,N-dicyclohexyl-2-benzothiazyl sulfenamide, N-oxydiethylene-2-benzothiazyl sulfenamide, N-tert-butyl-2-benzothiazyl sulfenamide, and N-tert-butyl-di(2-benzothiazole) sulfenimide.

[0046] Examples of the guanidine crosslinking accelerator include diphenyl guanidine and ditolyl guanidine.

[0047] Examples of the thiourea-based crosslinking accelerator include ethylene thiourea, diethylene thiourea, dibutyl thiourea, dilauryl thiourea, trimethyl thiourea, and diphenyl thiourea.

[0048] Aldehyde-ammonia based crosslinking accelerators include hexamethylenetetramine.

[0049] Examples of the dithiocarbamate crosslinking accelerator include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, and zinc N-pentamethylenedithiocarbamate.

[0050] Examples of xanthogenate-based crosslinking accelerators include zinc isopropylxanthogenate and zinc butylxanthogenate.

[0051] Examples of the fatty acid alkali metal salt crosslinking accelerator include sodium stearate and potassium stearate.

[0052] Examples of DBU salt crosslinking accelerators include DBU-carbonate, DBU-stearate, DBU-2-ethylhexyl salt, DBU-benzoate, DBU-salicylate, DBU-3-hydroxy-2-naphthoate, DBU-phenol resin salt, DBU-2-mercaptobenzothiazole salt, and DBU-2-mercaptobenzimidazole salt.

[0053] Examples of DBN salt-based crosslinking accelerators include DBN-carbonate, DBN-stearate, DBN-2-ethylhexyl salt, DBN-benzoate, DBN-salicylate, DBN-3-hydroxy-2-naphthoate, DBN-phenol resin salt, DBN-2-mercaptobenzothiazole salt, and DBN-2-mercaptobenzimidazole salt.

[0054] The amount of the crosslinking accelerator is preferably 0.1 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, relative to the polyether polymer having a main chain formed of a polyoxyethylene skeleton.

[0055] An acid acceptor can be used together with the crosslinking agent during crosslinking. Metal compounds and / or inorganic microporous crystals are preferred. Metal compounds include oxides, hydroxides, carbonates, carboxylates, silicates, borates, and phosphites of metals in Group II (Groups 2 and 12) of the periodic table; oxides, hydroxides, carboxylates, silicates, sulfates, nitrates, and phosphates of metals in Group III (Groups 3 and 13) of the periodic table; and oxides, basic carbonates, basic carboxylates, basic phosphites, basic sulfites, and tribasic sulfates of metals in Group IV (Groups 4 and 14) of the periodic table.

[0056] Specific examples of the metal compound include magnesia, magnesium hydroxide, aluminum hydroxide, barium hydroxide, sodium carbonate, magnesium carbonate, barium carbonate, quicklime, slaked lime, calcium carbonate, calcium silicate, calcium stearate, zinc stearate, calcium phthalate, calcium phosphite, zinc white, tin oxide, litharge, red lead, white lead, dibasic lead phthalate, dibasic lead carbonate, tin stearate, basic lead phosphite, basic tin phosphite, basic lead sulfite, and tribasic lead sulfate, of which sodium carbonate, magnesia, magnesium hydroxide, quicklime, slaked lime, calcium silicate, and zinc white are preferred.

[0057] The inorganic microporous crystals mentioned above refer to crystalline porous materials and are clearly distinguishable from amorphous porous materials such as silica gel and alumina. Examples of such inorganic microporous crystals include zeolites, aluminophosphate molecular sieves, layered silicates, synthetic hydrotalcites, and alkali metal titanates. Synthetic hydrotalcites are particularly preferred as acid acceptors.

[0058] The zeolites include natural zeolites, as well as various zeolites such as A-type, X-type, and Y-type synthetic zeolites, sodalites, natural or synthetic mordenite, and ZSM-5, as well as metal-substituted zeolites thereof, which may be used alone or in combination of two or more. The metal substituted in the metal is often sodium. Zeolites with high acid-accepting capacity are preferred, with A-type zeolites being preferred.

[0059] The synthetic hydrotalcite is represented by the following general formula (2). Mg X Zn Y Al Z (OH) (2(X+Y)+3Z-2) CO₃·wH₂O (2) [In the formula, x and y are real numbers from 0 to 10 satisfying the relationship x+y=1 to 10, z is a real number from 1 to 5, and w is a real number from 0 to 10.]

[0060] Examples of hydrotalcites represented by the general formula (2) include Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg 4.5 Al2(OH) 13 CO3, Mg4Al2(OH) 12 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·4H2O, Mg5Al2(OH) 14 CO3·4H2O, Mg3Al2(OH) 10 CO3·1.7H2O, Mg3ZnAl2(OH) 12 CO3·3.5H2O, Mg3ZnAl2(OH) 12 Examples include CO3.

[0061] The amount of the acid acceptor is preferably 0 to 50 parts by mass, may be 0.5 to 20 parts by mass, or may be 1 to 10 parts by mass, relative to the polyether polymer having a main chain formed of a polyoxyethylene skeleton.

[0062] The crosslinked product can be produced by heating a composition containing a polyether polymer whose main chain has a polyoxyethylene skeleton and a crosslinking agent. The composition can be produced by any means conventionally used in the field of polymer processing, such as an open roll, a Banbury mixer, or various kneaders. The procedure can be a normal procedure used in the field of polymer processing, for example, by first kneading only the polymer, then adding compounding ingredients other than the crosslinking agent and crosslinking accelerator to prepare kneaded compound A, and then kneading compound B, in which the crosslinking agent (and optionally the crosslinking accelerator) are added. Heating is usually carried out at 100 to 250°C. The crosslinking time varies depending on the temperature, but is usually between 0.5 and 300 minutes. Crosslinking molding may be carried out in an integrated manner, or a previously molded composition may be heated again to form a crosslinked product, or the crosslinked product may be heated first and then processed for molding. Specific methods for crosslinking molding include compression molding using a mold, injection molding, heating in a steam can, an air bath, infrared radiation, or microwave heating, among other methods.

[0063] In addition to the above, various fillers, plasticizers, processing aids (lubricants), flame retardants, pigments, antioxidants, conductive agents, and the like commonly used in the art can be optionally blended into the polymer material for a piezoelectric device, as long as the effects of the present invention are not impaired.

[0064] The polymer material for a piezoelectric device preferably contains a plasticizer, and the molecular weight of the plasticizer is preferably 50 to 8,000, more preferably 100 to 4,000, and particularly preferably 200 to 2,000.

[0065] Preferred examples of the plasticizer include polyols, copolyols, polycarboxylic acids, polyesters, phenol derivatives, and amide compounds, and plasticizers having an ether skeleton are preferred.

[0066] Examples of polyols include, but are not limited to, glycerin, diglycerin, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, butylene glycol, pentylene glycol, glycerol derivatives (such as propoxylated glycerol), glycidol, cyclohexanedimethanol, hexanediol, 2,2,4-trimethylpentane-1,3-diol, pentaerythritol, and trimethylolpropane.

[0067] Examples of polycarboxylic acids include, but are not limited to, citric acid, maleic acid, succinic acid, polyacrylic acid, and polymaleic acid.

[0068] Examples of polyesters include, but are not limited to, glycerol triacetate, acetylated monoglyceride, diethyl phthalate, triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate.

[0069] Examples of phenol derivatives include, but are not limited to, bisphenol A, bisphenol S, and the like.

[0070] Examples of amide compounds include, but are not limited to, N-methylpyrrolidone and the like.

[0071] The amount of the plasticizer to be added is preferably 0 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 1 part by mass or more, particularly preferably 5 parts by mass or more, and may be 10 parts by mass or more, 20 parts by mass or more, or may be 30 parts by mass or more, relative to 100 parts by mass of the polyether polymer having a main chain composed of a polyoxyethylene skeleton. The upper limit is preferably 500 parts by mass or less, more preferably 400 parts by mass or less, even more preferably 300 parts by mass or less, and particularly preferably 100 parts by mass or less, relative to 100 parts by mass of the polyether polymer having a main chain composed of a polyoxyethylene skeleton.

[0072] The amount of plasticizer in the polymer material for a piezoelectric device (100% by mass) is preferably 0.1% by mass or more as a lower limit, preferably 5% by mass or more, or may be 10% by mass or more, or may be 20% by mass or more as a lower limit, and is preferably 90% by mass or less, preferably 80% by mass or less, or preferably 70% by mass or less, or may be 60% by mass or less, or may be 50% by mass or less as an upper limit.

[0073] The amount of the polyether polymer and the plasticizer in the polymer material for a piezoelectric device (100% by mass) is preferably 60% by mass or more, more preferably 70% by mass or more, or may be 80% by mass or more, or may be 90% by mass or more, and the upper limit is preferably 99% by mass or less, more preferably 97% by mass or less, or may be 95% by mass or less.

[0074] Specific examples of processing aids include paraffin and hydrocarbon resins such as paraffin wax and hydrocarbon wax; fatty acids such as stearic acid and palmitic acid; fatty acid amides such as stearamide and oleyl amide; fatty acid esters such as n-butyl stearate; sorbitan fatty acid esters such as sorbitan stearate; fatty alcohols; and the like. These may be used alone or in combination of two or more.

[0075] The amount of the processing aid to be added may be 0 to 20 parts by mass, 0.1 to 20 parts by mass, or 0.3 to 10 parts by mass, relative to 100 parts by mass of the polymer.

[0076] The antioxidant used in the present invention can be a known antioxidant, and examples thereof include phenyl-α-naphthylamine, p-toluenesulfonylamido-diphenylamine, 4,4-α,α-dimethylbenzyldiphenylamine, high-temperature reaction product of diphenylamine and acetone, low-temperature reaction product of diphenylamine and acetone, low-temperature reaction product of diphenylamine, aniline, and acetone, reaction product of diphenylamine and diisobutylene, octylated diphenylamine, substituted diphenylamine, alkylated diphenylamine, diphenylamine derivatives, and the like. Conductor, N,N'-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-phenyl-N'-3-methacryloyloxy-2-hydroxypropyl-p-phenylenediamine, N,N'-bis-1-methylheptyl-p-phenylenediamine, N,N'-bis-1,4-dimethylpentyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, diallyl-p-phenylenediamine mixture, phenyl Octyl-p-phenylenediamine, mixture of phenyl-α-naphthylamine and diphenyl-p-phenylenediamine, polymer of 2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,5-di-tert-amylhydroquinone, 2,5-di-tert-butylhydroquinone, 1-oxy-3-methyl-4-isopropylbenzene, 2,6-di-tert-butyl-4-ethylphenol, butylhydroxyanisole, 2,6-di-tert-butyl-α-dimethylamine -p-Cresol, a mixture of 2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol and ortho-tert-butylphenol, styrenated phenols, alkylated phenols, mixtures of alkyl and aralkyl substituted phenols, phenol derivatives, 2,2'-methylene-bis-4-methyl-6-tert-butylphenol, 2,2'-methylene-bis-4-methyl-6-cyclohexylphenol, 2,2'-methylene-bis-4-ethyl-6-tert-butylphenol, 4,4-methylene-bis-2,6-Di-tert-butylphenol, methylene-bridged polyhydric alkylphenols, alkylated bisphenols, butylated reaction products of p-cresol and dicyclopentadiene, mixtures of polybutylated bisphenol A, 4,4-thiobis-6-tert-butyl-3-methylphenol, 4,4-butylidenebis-3-methyl-6-tert-butylphenol, 2,4-bisoctylthiomethyl-O-cresol, hindered phenols, hindered bisphenols 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, zinc salt of 2-mercaptomethylbenzimidazole, 4 and 5-mercaptomethylbenzimidazole, zinc salt of 4 and 5-mercaptomethylbenzimidazole, dioctadecyl disulfide, nickel diethyldithiocarbamate, nickel dibutyldithiocarbamate, 1,3-bisdimethylaminopropyl-2-thiourea, thiazolinone tributyl thiourea, bis 2-methyl-4-3-n-alkylthiopropionyloxy-5-tert-butylphenyl sulfide, bis 3,5-di-tert-butyl-4-hydroxybenzyl sulfide, mixed lauryl stearin thiodipropionate, cyclic acetal, a mixture of 60% polymer polyol and 40% hydrogenated silica, a special polyethylene glycol processed product with a two-molecule structure of polyethylene and polyethylene glycol, an inert filler and polymer polyol These include specially designed mixtures of benzotriazoles, complex antioxidants, enol ethers, 1,2,3-benzotriazole, 3-N-salicyloylamino-1,2,4-triazole, triazine derivative complexes, decamethylenedicarboxylic acid disalicyloyl hydrazide, N,N'-bis-3-3,5-di-tert-4-hydroxyphenylpropionyl hydrazine, and tetrakis-methylene-3-3',5'-di-tert-butyl 4'hydroxyphenylpropionate methane.

[0077] The blending amount of the antioxidant is preferably 0 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, based on the polyether polymer having a main chain formed of a polyoxyethylene skeleton.

[0078] The polymer material for a piezoelectric device is preferably used as an element for a piezoelectric device. The element for a piezoelectric device is an element that uses the polymer material for a piezoelectric device as a piezoelectric body and exhibits the piezoelectric effect or the inverse piezoelectric effect. An example of the element for a piezoelectric device is an element for a piezoelectric device provided with electrodes.

[0079] Examples of electrodes include metal materials such as gold, platinum, aluminum, stainless steel, nickel, tantalum, silver, and copper.

[0080] The piezoelectric device element of the present invention can be used in piezoelectric devices such as various sensors and actuators, including ultrasonic sensors, pressure sensors, tactile sensors, and strain sensors, utilizing the piezoelectric effect and / or the inverse piezoelectric effect.

[0081] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. The compounding ingredients used in the examples and comparative examples are shown below. Epihalohydrin polymer: Osaka Soda Co., Ltd. "Epichromer H" (epichlorohydrin homopolymer) Synthetic hydrotalcite: Kyowa Chemical Industry Co., Ltd. "DHT-4A-2" Lubricant: Kao Corporation "Splendor R300V" Crosslinking aid 1: Ouchi Shinko Chemical Industry Co., Ltd. "Noccela BZ" Crosslinking aid 2: Ouchi Shinko Chemical Industry Co., Ltd. "Noccela D" Crosslinking agent: Kawaguchi Chemical Industry Co., Ltd. "Actor TSH" Plasticizer: Fujifilm Wako Pure Chemical Corporation "PEG600"

[0082] Dynamic viscoelasticity measurement method Using Rheogel-E4000HP manufactured by UBM Co., Ltd., measurements were taken at 23°C in tension mode at a frequency of 1 Hz (storage modulus E').

[0083] How to create a voltage application test piece For the samples immersed in the plasticizer, the plasticizer adhering to the surface was wiped off, and test pieces 2 mm wide and 5 mm long were cut out and sandwiched between electrodes for use in a voltage application test.

[0084] Voltage application test method The measurement sample was sandwiched between electrodes (copper tape) and a specified voltage (up to 500V) was applied using a digital ultra-high resistance microcurrent meter (R8340 / 8340A) manufactured by Advantest Corporation. The sample was observed under a magnifying microscope, and samples that were confirmed to bend when voltage was applied were marked with a circle, and samples that were not were marked with an X.

[0085] Examples 1 to 6 The materials were kneaded in a kneader and open rolls according to the formulation (unit: parts by mass) shown in Table 1 to prepare an uncrosslinked rubber sheet having a thickness of 2 to 2.5 mm. Specifically, the kneading compounding ingredients A shown in Table 1 were kneaded for 4 to 5 minutes in a kneader heated to 120°C to obtain kneaded material A. Kneading compounding ingredients B were added to this kneaded material A, and the mixture was kneaded with kneading rolls heated to 60°C to obtain an uncrosslinked rubber sheet. The obtained rubber sheet was sandwiched between PET films coated with a release agent, and kneaded at 160°C for 15 minutes under a pressure of 100 kgf / cm. 2 The cross-linked material was subjected to press cross-linking at a temperature of 100°C, yielding a cross-linked material with a thickness of 50 to 90 μm. The resulting cross-linked material was immersed in a specified plasticizer to prepare a thin film sample with a thickness of 100 μm. This was then used as a polymer material for piezoelectric devices and evaluated. The results are shown in Table 2. The weight change rate △W (%) due to the plasticizer was calculated using the formula △W = {(W2 - W1) / W1} × 100, where W1 (g) is the weight of the polymer material before immersion and W2 (g) is the weight of the polymer material after immersion. Comparative Example 1 A crosslinked product was obtained by the same procedure as in Examples 1 to 6, and then used for various measurements as it was without immersion in a predetermined plasticizer.

[0086] [Table 1]

[0087] [Table 2]

[0088] From the results in Table 2, it was possible to confirm that the materials with reduced storage modulus (Examples 1 to 6) operated when a voltage was applied. Furthermore, it was possible to confirm that the materials operated when a voltage was applied, regardless of the amount of crosslinking agent shown in Table 1. On the other hand, no operation was confirmed when a voltage was applied in the material with a high storage modulus (Comparative Example 1). [Industrial Applicability]

[0089] The dielectric elastomer material using the polyether polymer of the present invention is very useful as a material for piezoelectric devices such as sensors and actuators.

Claims

1. A polymer material for a piezoelectric device, which contains a polyether polymer whose main chain has a polyoxyethylene skeleton, and has a storage modulus E' of 1.5 MPa or less at 23°C and a frequency of 1 Hz in dynamic viscoelasticity measurement (tensile mode).

2. The polymer material for a piezoelectric device according to claim 1 , further comprising a plasticizer.

3. 3. The polymer material for a piezoelectric device according to claim 2, wherein the plasticizer has an ether skeleton.

4. 2. The polymer material for piezoelectric devices according to claim 1, wherein the polyether-based polymer having a main chain composed of a polyoxyethylene skeleton contains at least one structural unit derived from a compound selected from epihalohydrins, alkylene oxides, and glycidyls.

5. A piezoelectric device element using the polymer material for piezoelectric devices according to any one of claims 1 to 4.

6. A piezoelectric device comprising the piezoelectric element according to claim 5 .

7. The piezoelectric device according to claim 6 , which is a sensor or an actuator.

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