Piezoelectric material compositions and piezoelectric materials

Abstract

To provide a piezoelectric material that can acquire piezoelectric characteristics without requiring high voltage application or stretching treatment, and exhibits high piezoelectric performance and elasticity when subjected to tensile stress and / or bending stress.SOLUTION: A composition for piezoelectric material contains a fluorine-based polymer (a), a polymer (b) and a crosslinker (c). The polymer (b) and the crosslinker (c) are a hydroxy group-containing polymer (b1) and an isocyanate group-containing crosslinker (c1), or an isocyanate group-containing polymer (b2) and a hydroxy group-containing crosslinker (c2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric material composition and a piezoelectric material. [Background technology]

[0002] Fluorine-based polymers such as polyvinylidene fluoride (PVDF) and vinylidene fluoride / trifluoroethylene copolymer (P(VDF / TrFE)) are used as piezoelectric materials with excellent piezoelectric properties. These piezoelectric materials are used in various piezoelectric elements, such as piezoelectric sensors, transducers, and infrared pyroelectric sensors.

[0003] For example, Patent Documents 1 to 3 describe piezoelectric materials containing polyvinylidene fluoride. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-304558 [Patent Document 2] Japanese Patent Publication No. 2011-192665 [Patent Document 3] International Publication No. 2020 / 012660 [Overview of the project] [Problems that the invention aims to solve]

[0005] When materials containing fluorine polymers are used as piezoelectric materials, polarization treatment is usually performed. For example, Patent Document 1 describes polarization treatment of a material containing polyvinylidene fluoride by stretching to impart piezoelectric properties to the material, and Patent Document 2 describes polarization treatment of a material containing polyvinylidene fluoride by applying a relatively high voltage to impart piezoelectric properties to the material.

[0006] However, depending on the application of the piezoelectric material, it may be required that the material be unstretched from the standpoint of material properties other than piezoelectricity. Furthermore, when piezoelectric properties are imparted by applying a high voltage, the applied high voltage may affect material properties other than piezoelectricity, so depending on the application in which the piezoelectric material is used, it may not satisfy the other material properties other than piezoelectricity.

[0007] Furthermore, as the application of piezoelectric materials to applications such as clothing and medical sensors progresses, there is a growing demand not only for piezoelectric properties when pressure is applied to the piezoelectric material, such as when the surface of a piezoelectric film is pressed, but also for piezoelectric properties when tensile stress or bending stress is applied to the piezoelectric material. Patent Document 3 describes a piezoelectric material that is excellent in flexibility and stretchability and has piezoelectric properties even without stretching treatment, but its piezoelectric properties when tensile stress or bending stress is applied are not sufficient, and there is a demand for further improvement. In addition, flexibility and stretchability are also required for such piezoelectric materials.

[0008] Therefore, the object of the present invention is to provide a piezoelectric material composition that can impart piezoelectric properties even without applying high voltage, stretching, etc., and that provides a piezoelectric material having high piezoelectricity and stretchability when tensile stress and / or bending stress are applied to the piezoelectric material. [Means for solving the problem]

[0009] The inventors of the present invention diligently studied various components contained in piezoelectric material compositions in order to solve the above problems. As a result, they found that the above problems can be solved by using a piezoelectric material containing a crosslinked polymer containing urethane bonds, and thus completed the present invention.

[0010] In other words, the present invention includes the following preferred embodiments. [1] Contains a fluorine polymer (a), a polymer (b), and a crosslinking agent (c), A piezoelectric material composition wherein the polymer (b) and the crosslinking agent (c) are a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and / or an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2). [2] A piezoelectric material composition comprising at least one component, comprising an agent containing a fluorine polymer (a), a polymer (b), and a crosslinking agent (c), A piezoelectric material composition comprising at least two components: a first component containing a fluorine-based polymer (a) and a polymer (b), and a second component containing a crosslinking agent (c), A piezoelectric material composition comprising at least two components: a first component containing a fluorine-based polymer (a) and a crosslinking agent (c), and a second component containing a polymer (b), or A piezoelectric material composition comprising at least three components: a first component containing a fluorine-based polymer (a), a second component containing a polymer (b), and a third component containing a crosslinking agent (c). The piezoelectric material composition described in [1]. [3] A piezoelectric material composition according to [1] or [2], based on the total amount of the fluorine polymer (a), polymer (b), and crosslinking agent (c), wherein the amount of the fluorine polymer (a) is 60 to 99% by mass, and the total amount of the polymer (b) and crosslinking agent (c) is 1 to 40% by mass. [4] The piezoelectric material composition according to any one of [1] to [3], wherein the total amount of the fluorine polymer (a), polymer (b), and crosslinking agent (c) is 80% by mass or more based on the solid content of the piezoelectric material composition. [5] The hydroxyl group-containing polymer (b1) is a (meth)acrylic polymer having a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. The hydroxyl group-containing crosslinking agent (c2) is a piezoelectric material composition according to any one of [1] to [4], having a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. [6] The piezoelectric material composition according to any one of [1] to [5], wherein the isocyanate group-containing crosslinking agent (c1) is a blocked polyisocyanate. [7] The equivalent ratio (hydroxyl group:isocyanate group) of the hydroxyl group-containing polymer (b1) and the isocyanate group-containing crosslinking agent (c1) is 0.5:1.5 to 1.5:0.5. The equivalent ratio (hydroxyl group:isocyanate group) of the hydroxyl group-containing crosslinking agent (c2) and the isocyanate group-containing polymer (b2) is 0.5:1.5 to 1.5:0.5. A piezoelectric material composition according to any one of [1] to [6]. [8] A piezoelectric material composition according to any one of [1] to [7], wherein the weight-average molecular weight of the fluorine polymer (a) is 100,000 or more. [9] The piezoelectric material composition according to any one of [1] to [8], wherein the fluorine polymer is a vinylidene fluoride polymer.

[10] The piezoelectric material composition according to any one of [1] to [9], wherein the fluorine polymer (a) is a vinylidene fluoride / trifluoroethylene copolymer, and the amount of constituent units derived from vinylidene fluoride in the copolymer is 55 to 90 mol% based on the total amount of constituent units. A piezoelectric material formed from any of the piezoelectric material compositions described in

[11] [1] to

[10] .

[12] A piezoelectric material containing a fluorine polymer (a) and a crosslinked polymer (d) containing a urethane bond.

[13] The piezoelectric material according to

[12] , wherein the crosslinked polymer (d) comprises at least a structure derived from polymer (b) and a structure derived from crosslinking agent (c), and the polymer (b) and the crosslinking agent (c) are a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and / or an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2).

[14] The piezoelectric material according to

[12] or

[13] , based on the total amount of fluorine polymer (a) and crosslinked polymer (d), wherein the amount of fluorine polymer (a) is 60 to 99% by mass and the amount of crosslinked polymer (d) is 1 to 40% by mass. [Effects of the Invention]

[0011] According to the present invention, it is possible to impart piezoelectric properties even without applying high voltage, stretching, etc., and it is possible to provide a piezoelectric material having high piezoelectricity and elasticity when tensile stress and / or bending stress are applied to the piezoelectric material, and a piezoelectric material composition for manufacturing the piezoelectric material. [Brief explanation of the drawing]

[0012] [Figure 1] This is a diagram illustrating the method for calculating hysteresis loss. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below. However, the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention. In this specification, numerical ranges indicated by "~" include their upper and lower limits.

[0014] The piezoelectric material composition of the present invention contains a fluorine-based polymer (a), a polymer (b), and a crosslinking agent (c), wherein the polymer (b) and the crosslinking agent (c) are a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and / or an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2). The inventors have found that by forming a piezoelectric material using a piezoelectric material composition containing a fluorine-based polymer (a), a specific polymer (b), and a specific crosslinking agent (c), a piezoelectric material containing a fluorine-based polymer (a) and a crosslinking polymer (d) containing a urethane bond can be obtained, thereby exhibiting piezoelectric properties even without polarization treatment by stretching or application of high voltage, and / or addition of other compounds, and obtaining a piezoelectric material that has high piezoelectricity and stretchability when tensile stress and / or bending stress are applied to the piezoelectric material. Furthermore, the piezoelectric material of the present invention may be subjected to conventional techniques for exhibiting and improving piezoelectric properties, such as stretching, polarization at relatively high voltages, and compound addition, as long as it satisfies the material properties required for the application of the piezoelectric material.

[0015] The detailed reason why the piezoelectric material of the present invention exhibits piezoelectric properties without polarization treatment by stretching or application of high voltage, or addition of compounds, is not clear. However, the crosslinked polymer (d) containing urethane bonds and the fluorine-based polymer (a) are compatible, and the dipoles in their respective constituent units interact electrostatically. Therefore, when an external force is applied to the piezoelectric material and it expands or contracts, the fluorine-based polymer (a) follows the deformation of the relatively flexible polymer (d), making the relatively hard fluorine-based polymer (a) more easily deformable. This is presumed to increase the change in potential of the fluorine-based polymer (a) associated with expansion and contraction, allowing for the extraction of a relatively large charge. Furthermore, it is believed that the piezoelectric material containing the crosslinked polymer (d) containing urethane bonds achieves both high piezoelectricity and elasticity when tensile stress and / or bending stress are applied to the piezoelectric material. The high elasticity of the piezoelectric material allows for the continuous extraction of a large charge. Note that the crosslinked polymer (d) containing urethane bonds contains urethane bonds in the crosslinked structure.

[0016] The piezoelectric material composition of the present invention contains a fluorine-based polymer (a), a polymer (b), and a crosslinking agent (c).

[0017] [Polymer (b) and crosslinking agent (c)] The piezoelectric material composition of the present invention contains a polymer (b) and a crosslinking agent (c), wherein, in one embodiment of the present invention, the polymer (b) and the crosslinking agent (c) are a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and in another embodiment of the present invention, they are an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2). The hydroxyl groups of the hydroxyl group-containing polymer (b1) and the isocyanate groups of the isocyanate group-containing crosslinking agent (c1) react upon heating to form urethane bonds. As a result, the piezoelectric material formed using the piezoelectric material composition contains a crosslinked polymer (d) containing urethane bonds. Similarly, the isocyanate groups of the isocyanate group-containing polymer (b2) and the hydroxyl groups of the hydroxyl group-containing crosslinking agent (c2) also react upon heating to form urethane bonds. As a result, the piezoelectric material formed using the piezoelectric material composition contains a crosslinked polymer (d) containing urethane bonds. In either case, the urethane bonds are included in the crosslinked structure.

[0018] When a piezoelectric material composition contains a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), the piezoelectric material composition may contain one type of hydroxyl group-containing polymer (b1) or two or more types of hydroxyl group-containing polymers (b1). Furthermore, the composition may contain one type of isocyanate group-containing crosslinking agent (c1) or two or more types of isocyanate group-containing crosslinking agents (c1).

[0019] When a piezoelectric material composition contains an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2), the piezoelectric material composition may contain one type of isocyanate group-containing polymer (b2) or two or more types of isocyanate group-containing polymers (b2). Furthermore, the composition may contain one type of hydroxyl group-containing crosslinking agent (c2) or two or more types of hydroxyl group-containing crosslinking agents (c2).

[0020] The weight-average molecular weight of polymer (b) contained in the piezoelectric material composition of the present invention is preferably 10,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, and particularly preferably 150,000 or more. When the weight-average molecular weight of polymer (b) is above the lower limit of the above value, it is easier to increase the strength and durability of the piezoelectric material. From the viewpoint of easily obtaining the effects of the present invention, the weight-average molecular weight of polymer (b) may be preferably 500,000 or more, more preferably 800,000 or more, and even more preferably 1,000,000 or more. Furthermore, from the viewpoint of ease of polymer production, the weight-average molecular weight of polymer (b) is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,400,000 or less. The weight-average molecular weight of polymer (b) can be measured using gel permeation chromatography. Details of the measurement conditions, etc., are described in the examples.

[0021] (Hydroxygroup-containing polymer (b1)) Examples of hydroxyl group-containing polymers (b1) include (meth)acrylic polymers having at least one hydroxyl group. Preferably, the hydroxyl group-containing polymer (b1) is a (meth)acrylic polymer having a hydroxyl group.

[0022] In a preferred embodiment of the present invention, when the hydroxyl group-containing polymer (b1) is a (meth)acrylic polymer having hydroxyl groups, the (meth)acrylic polymer is defined as formula (I): [ka] [In formula (I), R 1 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms, where R 1 At least one hydrogen atom may be substituted with a halogen atom. R 2 This represents a linear or branched alkyl group having 1 to 10 carbon atoms having at least one hydroxyl group, an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, a phenyl group, or a phenylalkylene group having 1 to 4 carbon atoms. R 3 This represents a linear or branched alkyl group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, a phenyl group, or a phenylalkylene group having 1 to 4 carbon atoms. Here, R 2 In the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group, at least one carbon atom may be substituted with -O-, -N-, or -S-; at least one hydrogen atom of the alkylene group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with a hydroxyl group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group; and at least one hydrogen atom of the phenyl group in the phenylalkylene group may be substituted with a hydroxyl group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. R 3In the above, at least one carbon atom of the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group may be substituted with -O-, -N- or -S-, and at least one hydrogen atom of the alkylene group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with a halogen atom, an alkyl group having 1 to 6 carbon atoms, and / or an alkoxy group having 1 to 6 carbon atoms, and at least one hydrogen atom of the phenyl group in the phenyl group and the phenylalkylene group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and / or a cyano group, m1 is an integer of 1 or more, and n1 is 0 or an integer of 1 or more] (meth)acrylic polymers represented by the formula are mentioned. In the present specification, the group R in formula (I) 2 the structural unit having is also referred to as "structural unit M1", and the group R in formula (I) 3 the structural unit having is also referred to as "structural unit N1". In this embodiment, the (meth)acrylic polymer may be a polymer having only one type or two or more types of structural unit M1, or may be a polymer having one type or two or more types of structural unit M1 and one type or two or more types of structural unit N1. In addition, the (meth)acrylic polymer may further have another structural unit different from structural unit M1 and structural unit N1 in addition to structural unit M1.

[0023] R in formula (I) 1 each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms, wherein at least one hydrogen atom of R 1 may be substituted with a halogen atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group, and a group in which at least one hydrogen atom of these groups is substituted with a halogen atom may also be used. The halogen atom is preferably at least one atom selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, more preferably a fluorine atom and / or a chlorine atom, and still more preferably a fluorine atom. R in formula (I)1 Preferably, this is a hydrogen atom, a fluoro group, or a methyl group.

[0024] R 1 Specific examples include, but are not limited to, hydrogen atoms, fluoro groups, trifluoromethyl groups, difluoromethyl groups, monofluoromethyl groups, trifluoroethyl groups, difluoroethyl groups, monofluoroethyl groups, and monochloromethyl groups.

[0025] R in equation (I) 3 R represents (1) a linear or branched alkyl group having 1 to 10 carbon atoms, (2) an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, (3) a phenyl group, or (4) a phenylalkylene group having 1 to 4 carbon atoms. 3 In the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group, at least one carbon atom may be substituted with -O-, -N-, or -S-; at least one hydrogen atom of the alkylene group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group; and at least one hydrogen atom of the phenyl group in the phenylalkylene group may be substituted with a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group.

[0026] The number of carbon atoms in the alkyl group having 1 to 6 carbon atoms and the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 2. The alkyl chain portion in the alkyl group having 1 to 6 carbon atoms and the alkoxy group may be either linear or branched.

[0027] R in equation (I) 3However, (1) when the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms, the number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, from the viewpoint of manufacturability of the raw material monomer for producing the (meth)acrylic polymer represented by the above formula (I). In this specification, the alkyl group may be linear or branched. Examples of alkyl groups include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, 1,1-dimethylpropyl group, isoamyl group, n-hexyl group, isohexyl group, n-octyl group, etc. At least one carbon atom of the alkyl group having 1 to 10 prime numbers may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the alkyl group having 1 to 10 carbon atoms may be substituted with a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, and / or an alkoxy group having 1 to 6 carbon atoms. R in formula (I) above 3 From the viewpoint of easily enhancing piezoelectric properties, preferably a linear or branched alkyl group having 1 to 10 carbon atoms and 1 to 10 halogen atoms, more preferably a linear or branched alkyl group having 2 to 10 carbon atoms and 2 to 10 halogen atoms, even more preferably a linear or branched alkyl group having 3 to 8 carbon atoms and 3 to 8 halogen atoms, and even more preferably a linear or branched alkyl group having 3 to 6 carbon atoms and 3 to 8 halogen atoms.

[0028] At least one carbon atom of the alkyl group may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the alkyl group may be substituted with a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group.

[0029] The alkyl group in which at least one hydrogen atom is substituted with a halogen atom is preferably a C1-C10 alkyl group having 1-10 halogen atoms, more preferably a C1-C6 alkyl group having 1-10 halogen atoms, even more preferably a C2-C8 alkyl group having 1-10 halogen atoms, and even more preferably a C3-C6 alkyl group having 1-10 halogen atoms. Examples of such groups include those selected from the group consisting of trifluoromethyl, difluoromethyl, monofluoromethyl, trifluoroethyl, difluoroethyl, monofluoroethyl, octafluoropropyl, heptafluoropropyl, hexafluoropropyl, pentafluoropropyl, tetrafluoropropyl, trifluoropropyl, difluoropropyl, monofluoropropyl, octafluorobutyl, heptafluorobutyl, hexafluorobutyl, pentafluorobutyl, tetrafluorobutyl, trifluorobutyl, difluorobutyl, monofluorobutyl, octafluoropentyl, heptafluoropentyl, hexafluoropentyl, pentafluoropentyl, tetrafluoropentyl, trifluoropentyl, difluoropentyl, monofluoropentyl, trichloromethyl, dichloromethyl, and monochloromethyl groups.

[0030] A C1-C6 alkyl group, in which at least one hydrogen atom is substituted with a C1-C6 alkyl group, is a group in which a C1-C10 alkyl group forms the main chain, and at least one hydrogen atom of the alkyl group is substituted with a C1-C6 alkyl group. As long as the number of carbon atoms in the main chain alkyl group is between 1 and 10, the total number of carbon atoms in the alkyl group as a whole may exceed 10. An example of such an alkyl group is the 2-ethylhexyl group. Note that if the total number of carbon atoms in the alkyl group as a whole does not exceed 10, the group is also included in the definition of a C1-C10 branched alkyl group.

[0031] A C1-C10 alkyl group in which at least one hydrogen atom is substituted with a C1-C6 alkoxy group is preferably a C1-C6 alkyl group substituted with a C1-C6 alkoxy group. Examples of such groups include, for example, a methoxyethyl group, an ethoxyethyl group, and a methoxybutyl group.

[0032] At least one carbon atom of the alkyl group described above may be substituted with -O-, -N-, or -S-. For example, R in formula (I) 3 This represents a linear or branched alkyl group having 1 to 10 carbon atoms, wherein at least one carbon atom of the alkyl group may be substituted with -O-. For example, such a group is represented by formula (f): [ka] [During the ceremony, r and s each independently represent numbers from 1 to 3. X represents a methyl group, At least one hydrogen atom in formula (III) may be substituted with a C1 or C2 alkyl group and / or a C1-C6 alkoxy group. Examples of such groups include those represented by . At least one hydrogen atom of the group may be substituted with a halogen atom. Preferred examples of such groups include the trifluoromethoxyethyl group and the trifluoromethoxypropyl group.

[0033] R in equation (I) 3 However, (2) in the case of a 3- to 12 carbon alicyclic hydrocarbon group including a 3- to 6 carbon alicyclic structure, an example of a 3- to 6 carbon alicyclic structure is cyclohexane. At least one carbon atom of the 3- to 12 carbon alicyclic hydrocarbon group may be substituted with -O-, -N- or -S-, and at least one hydrogen atom of the 3- to 12 carbon alicyclic hydrocarbon group may be substituted with a halogen atom, a 1- to 6 carbon alkyl group, and / or a 1- to 6 carbon alkoxy group, or may be substituted with a halogen atom, a 1 or 2 carbon alkyl group, and / or a 1- to 6 carbon alkoxy group.

[0034] Examples of alicyclic hydrocarbon groups having 3 to 12 carbon atoms, including alicyclic structures having 3 to 6 carbon atoms in which at least one carbon atom is substituted with an oxygen atom (-O-), include epoxy groups in which one carbon atom of a 3-carbon alicyclic hydrocarbon group is substituted with an oxygen atom, oxetanyl rings in which one carbon atom of a 4-carbon alicyclic hydrocarbon group is substituted with an oxygen atom, dioxolane rings in which two carbon atoms of a 5-carbon alicyclic hydrocarbon group are substituted with oxygen atoms, and dioxane rings in which two carbon atoms of a 6-carbon alicyclic hydrocarbon group are substituted with oxygen atoms. Note that the hydrogen atoms on these rings may be substituted with C1 or C2 alkyl groups. Specific examples of such groups include 3-ethyl-3-oxetanyl methyl acrylate, 2-methyl-2-ethyl-1,3-dioxolane-4-yl)methyl acrylate, and cyclic trimethylolpropane formal acrylate.

[0035] In equation (I) above, R 3 However, (3) in the case of a phenyl group, at least one carbon atom of the phenyl group may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom may be substituted with a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. A phenyl group in which at least one hydrogen atom, particularly the para hydrogen atom, is substituted with a C1-C4 (preferably 1 or 2) alkyl group, and the hydrogen atom of the C1-C4 alkyl group is substituted with a halogen atom, is preferred from the viewpoint of easily improving properties of piezoelectric materials such as stretchability and flexibility.

[0036] A phenyl group in which at least one hydrogen atom of the phenyl group may be substituted with a halogen atom, a C1-C4 alkyl group, and / or a C1-C6 alkoxy group, etc., may also be a group in which at least one hydrogen atom is substituted with a halogen atom. 3 When this is the group, it is easier to improve the properties of the piezoelectric material, such as its elasticity and flexibility.

[0037] R in equation (I)3 However, (4) if it is a phenylalkylene group containing an alkylene group having 1 to 4 carbon atoms, at least one carbon atom of the alkylene group may be substituted with -O-, -N- or -S-, and at least one hydrogen atom of the phenyl group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and / or a cyano group.

[0038] A phenylalkylene group in which at least one carbon atom of the phenylalkylene group is substituted with -O- is given by formula (g): [ka] [p and q are independently either 2 or 3] Examples include groups represented by , and groups in which at least one hydrogen atom of the alkylene and phenyl portions of the group is substituted with a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. At least one hydrogen atom in the above group may be substituted with a halogen atom. 3 When the above-mentioned basis is present, it is easier to improve other properties of piezoelectric materials, such as elongation and flexibility.

[0039] As described above, a phenylalkylene group may have at least one hydrogen atom on the alkylene group substituted with a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group, and / or a phenyl group substituted with a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. 3 When this group is present, it is easier to improve other properties of the piezoelectric material, such as elongation and flexibility.

[0040] R in equation (I) 2R represents a phenylalkylene group having at least one hydroxyl group, which includes (1) a linear or branched alkyl group having 1 to 10 carbon atoms, (2) an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, (3) a phenyl group, or (4) an alkylene group having 1 to 4 carbon atoms. 2 In the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group, at least one carbon atom may be substituted with -O-, -N-, or -S-; at least one hydrogen atom of the alkylene group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with a hydroxyl group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group; and at least one hydrogen atom of the phenyl group in the phenyl group and the phenylalkylene group may be substituted with a hydroxyl group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. Such a group is R in formula (I). 3 In addition to the groups exemplified above, there are also groups that have at least one hydroxyl group.

[0041] The number of carbon atoms in the alkyl group having 1 to 6 carbon atoms and the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 2. The alkyl chain portion in the alkyl group having 1 to 6 carbon atoms and the alkoxy group may be either linear or branched.

[0042] R in equation (I) 2 The number of hydroxyl groups in is not particularly limited, but from the viewpoint of easily improving the compatibility (hereinafter simply referred to as compatibility) between the fluorine-based polymer (a) and polymer (d) described above, it is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 to 2.

[0043] R in equation (I) 2However, if the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms and having at least one hydroxyl group, the number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, from the viewpoint of the manufacturability of the raw material monomer for producing the (meth)acrylic polymer represented by formula (I) above. An example of an alkyl group is R in formula (I). 3 Examples include the groups described above, which further have at least one hydroxyl group.

[0044] Examples of alkyl groups with 1 to 10 carbon atoms substituted with a hydroxyl group include, for example, hydroxymethyl group, hydroxyethyl group, hydroxyn-propyl group, hydroxyisopropyl group, hydroxyn-butyl group, hydroxyisobutyl group, and hydroxytert-butyl group.

[0045] Examples of C1-C10 alkyl groups substituted with a hydroxyl group and a C1-C6 alkoxy group include groups having a C1-C6 hydroxyalkoxy group and a C1-C6 alkyl group, specifically hydroxymethoxyethyl group, hydroxyethoxyethyl group, hydroxypropyloxypropyl group, and the like.

[0046] Among the alkyl groups mentioned above, from the viewpoint of compatibility, alkyl groups having 1 to 6 carbon atoms that are substituted with hydroxyl groups, and optionally substituted with alkoxy groups having 1 to 2 carbon atoms, are preferred, and alkyl groups having 1 to 4 carbon atoms that are substituted with hydroxyl groups, and optionally substituted with alkoxy groups having 1 to 2 carbon atoms, are more preferred.

[0047] R in equation (I) 2However, in the case of a C3-C6 alicyclic hydrocarbon group having at least one hydroxyl group, (2) a C3-C6 alicyclic structure, an example of a C3-C6 alicyclic structure is cyclohexane. At least one carbon atom of the C3-C12 alicyclic hydrocarbon group may be substituted with -O-, -N- or -S-, and at least one hydrogen atom of the C3-C12 alicyclic hydrocarbon group may be substituted with a hydroxyl group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group, or may be substituted with a hydroxyl group, a halogen atom, a C1 or C2 alkyl group, and / or a C1-C6 alkoxy group.

[0048] (2) Examples of alicyclic hydrocarbon groups having 3 to 12 carbon atoms, including an alicyclic structure having 3 to 6 carbon atoms, which has at least one hydroxyl group, include R in formula (I), which has at least one more hydroxyl group. 3 The basis for this can be found in the above-mentioned points.

[0049] R in equation (I) 2 However, in the case of a (3) phenyl group having at least one hydroxyl group, at least one carbon atom of the phenyl group may be substituted with -O-, -N- or -S-, and at least one hydrogen atom may be substituted with a hydroxyl group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. A group in which at least one hydrogen atom of the phenyl group is substituted with a hydroxyl group, at least one hydrogen atom, particularly the para hydrogen atom, is substituted with a C1-C4 (preferably 1 or 2) alkyl group, and the hydrogen atom of the C1-C4 alkyl group is substituted with a halogen atom is preferred in terms of easily improving other properties of the piezoelectric material, such as elongation and flexibility.

[0050] A phenyl group in which at least one hydrogen atom of the phenyl group may be substituted with a hydroxyl group, a halogen atom, a C1-C4 alkyl group, and / or a C1-C6 alkoxy group, etc., may also be a group in which at least one hydrogen atom is substituted with a hydroxyl group and a halogen atom. 2When this group is present, it is easier to improve other properties of the piezoelectric material, such as its elongation and flexibility.

[0051] R in equation (I) 2 However, if (4) a phenylalkylene group having at least one hydroxyl group and containing a C1-C4 alkylene group, then at least one carbon atom of the alkylene group may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the phenyl group may be substituted with a hydroxyl group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group.

[0052] A phenylalkylene group having a hydroxyl group, in which at least one carbon atom of the alkylene group is substituted with -O-, is a phenylalkylene group having at least one hydroxyl group, as R in formula (I). 3 The basis for this can be found in the above-mentioned points.

[0053] In formula (I), m1 and n1 are the group R in formula (I) that is contained in the (meth)acrylic polymer represented by formula (I). 2 A constituent unit M1 having and the base R in formula (I) 3 This represents the number of repeating constituent units N1, the number of moles of constituent units M1 and N1 contained in the (meth)acrylic polymer, and the number of moles of constituent units N1. m1 is an integer of 1 or more, and n1 is 0 or an integer of 1 or more. The ratio of the total number of moles of constituent units M1 and N1 to the total number of moles of all constituent units contained in the (meth)acrylic polymer (the ratio of the sum of m1 and n1 to the total number of constituent units) is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, particularly preferably 90% or more, and particularly more preferably 95% or more, from the viewpoint of compatibility and ease of improving the flexibility and stretchability of the resulting piezoelectric material. The upper limit of this ratio is 100% or less.

[0054] The (meth)acrylic polymer represented by formula (I) contains the group R in formula (I). 2The ratio of the number of moles of constituent unit M1 having to the total number of moles of constituent unit M1 and constituent unit N1 contained in the (meth)acrylic polymer is preferably 70% or more, more preferably 80% or more, even more preferably 85% or more, even more preferably 90% or more, particularly preferably 95% or more, particularly more preferably 98% or more, and very preferably 99% or more, from the viewpoint of compatibility. The upper limit of this ratio is preferably 99.9% or less, more preferably 99.8% or less, and even more preferably 99.7% or less, from the viewpoint of easily increasing the flexibility and stretchability of the resulting piezoelectric material. The above ratio is calculated by the formula m1 / (m1+n1)×100.

[0055] In a preferred embodiment of the present invention, the (meth)acrylic polymer represented by formula (I) is R in formula (I). 1 , R 2 and R 3 However, it is a polymer that represents the following group: R 1 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. R 2 This represents a linear or branched alkyl group having 1 to 10 carbon atoms and having at least one hydroxyl group, preferably a linear or branched alkyl group having 1 to 10 carbon atoms and having one hydroxyl group. R 3 This represents a linear or branched alkyl group having 1 to 10 carbon atoms. Here, R 2 The alkyl group in the above may have at least one carbon atom substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the alkyl group may be substituted with a hydroxyl group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group. R 3 In the alkyl group, at least one carbon atom may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the alkyl group may be substituted with a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group.

[0056] When polymer (b) contained in the piezoelectric material composition of the present invention is a hydroxyl group-containing polymer (b1), it is preferable that the hydroxyl group-containing polymer (b1) is a (meth)acrylic polymer having a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. The hydroxyl value of the hydroxyl group-containing polymer (b1) is more preferably 0.1 mg KOH / g or more and 90 mg KOH / g or less, and even more preferably 0.2 mg KOH / g or more and 80 mg KOH / g or less. In one embodiment of the present invention, the hydroxyl value of the hydroxyl group-containing polymer (b1) may be even more preferably 50 mg KOH / g or less, 30 mg KOH / g or less, 20 mg KOH / g or less, 10 mg KOH / g or less, 5 mg KOH / g or less, etc. The hydroxyl value of the hydroxyl group-containing polymer (b1) is defined as the number of milligrams of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl group when acetylating 1 g of the hydroxyl group-containing polymer (b1), and is measured based on the potentiometric titration method specified in JIS K 0070:1992. The number of hydroxyl groups in the hydroxyl group-containing polymer (b1) can also be calculated from the amount of monomers (constituent units) used in the synthesis of the hydroxyl group-containing polymer (b1), as well as the structure of the hydroxyl group-containing polymer (b1), and the integral values ​​of the chemical shifts and peaks measured by NMR.

[0057] (Isocyanate group-containing polymer (b2)) Examples of isocyanate group-containing polymers (b2) include (meth)acrylic polymers having at least one isocyanate group. Preferably, the isocyanate group-containing polymer (b2) is a (meth)acrylic polymer having an isocyanate group.

[0058] In a preferred embodiment of the present invention, if the isocyanate group-containing polymer (b2) is an isocyanate group-containing (meth)acrylic polymer, the (meth)acrylic polymer is a polymer of formula (II): [ka] [In formula (II), R 4 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms, where R 4 At least one hydrogen atom may be substituted with a halogen atom. R 5 This represents a linear or branched alkyl group having 1 to 10 carbon atoms having at least one isocyanate group, an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, a phenyl group, or a phenylalkylene group having 1 to 4 carbon atoms. R 6 This represents a linear or branched alkyl group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, a phenyl group, or a phenylalkylene group having 1 to 4 carbon atoms. Here, R 5 In the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group, at least one carbon atom may be substituted with -O-, -N-, or -S-; at least one hydrogen atom of the alkylene group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with an isocyanate group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group; and at least one hydrogen atom of the phenyl group in the phenylalkylene group may be substituted with an isocyanate group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. R 6In the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group, at least one carbon atom may be substituted with -O-, -N-, or -S-; at least one hydrogen atom of the alkyl group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group; and at least one hydrogen atom of the phenyl group in the phenylalkylene group may be substituted with a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. m2 is an integer greater than or equal to 1, and n2 is an integer greater than or equal to 0 or 1. Examples include (meth)acrylic polymers represented by . In this specification, the group R in formula (II) 4 A constituent unit having is also called "constituent unit M2", and the base R in formula (I) 5 A constituent unit having the above is also referred to as "constituent unit N2". In this embodiment, the (meth)acrylic polymer may be a polymer having only one or more types of constituent units M2, or a polymer having one or more types of constituent units M2 and one or more types of constituent units N2. Furthermore, the (meth)acrylic polymer may have, in addition to constituent units M2, other constituent units different from constituent units M2 and N2. Note that the isocyanate group in the isocyanate group-containing polymer (b2) may be an isocyanate group (-N=C=O) or a blocked isocyanate group. Examples of blocking agents for the blocked isocyanate group include those described later with respect to the isocyanate group-containing crosslinking agent (c1).

[0059] R in equation (II) 4 Regarding R in equation (I), 1 The same applies to the description regarding R 1 A preferred embodiment relating to R 4 The same applies to this matter.

[0060] R in equation (II)6 Regarding R in equation (I), 3 The same applies to the description regarding R 3 A preferred embodiment relating to R 6 The same applies to this matter.

[0061] R in equation (II) 5 R represents a phenylalkylene group having at least one isocyanate group, which includes (1) a linear or branched alkyl group having 1 to 10 carbon atoms, (2) an alicyclic hydrocarbon group having 3 to 12 carbon atoms including an alicyclic structure having 3 to 6 carbon atoms, (3) a phenyl group, or (4) an alkylene group having 1 to 4 carbon atoms. 2 In the alkyl group, the alicyclic hydrocarbon group, the phenyl group, and the phenylalkylene group, at least one carbon atom may be substituted with -O-, -N-, or -S-; at least one hydrogen atom of the alkylene group in the alkyl group, the alicyclic hydrocarbon group, and the phenylalkylene group may be substituted with an isocyanate group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group; and at least one hydrogen atom of the phenyl group in the phenyl group and the phenylalkylene group may be substituted with an isocyanate group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. Such a group is R in formula (I). 3 In addition to the groups exemplified above, there are also groups that have at least one isocyanate group.

[0062] The number of carbon atoms in the alkyl group having 1 to 6 carbon atoms and the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 2. The alkyl chain portion in the alkyl group having 1 to 6 carbon atoms and the alkoxy group may be either linear or branched.

[0063] R in equation (II) 5The number of isocyanate groups in isocyanate is not particularly limited, but from the viewpoint of compatibility, it is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 to 2.

[0064] R in equation (II) 5 However, if the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms and having at least one isocyanate group, the number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, from the viewpoint of the manufacturability of the raw material monomer for producing the (meth)acrylic polymer represented by formula (II) above. An example of an alkyl group is R in formula (I). 3 Examples include the groups described above, which further have at least one isocyanate group.

[0065] Examples of C1-C10 alkyl groups substituted with isocyanate groups include isocyanatomethyl, isocyanatoethyl, isocyanaton-propyl, isocyanatoisopropyl, isocyanaton-butyl, isocyanatoisobutyl, and isocyanatotert-butyl.

[0066] Examples of C1-C10 alkyl groups substituted with an isocyanate group and a C1-C6 alkoxy group include groups having a C1-C6 isocyanatoalkoxy group and a C1-C6 alkyl group, specifically isocyanatomethoxyethyl group, isocyanatoethoxyethyl group, isocyanatopropyloxypropyl group, and the like.

[0067] Among the alkyl groups mentioned above, from the viewpoint of compatibility, alkyl groups having 1 to 6 carbon atoms that are substituted with isocyanate groups, which may be substituted with alkoxy groups having 1 to 2 carbon atoms, are preferred, and alkyl groups having 1 to 4 carbon atoms that are substituted with isocyanate groups, which may be substituted with alkoxy groups having 1 to 2 carbon atoms, are more preferred.

[0068] R in equation (II) 5However, in the case of a C3-C6 alicyclic hydrocarbon group having at least one isocyanate group, (2) a C3-C6 alicyclic structure, an example of a C3-C6 alicyclic structure is cyclohexane. At least one carbon atom of the C3-C12 alicyclic hydrocarbon group may be substituted with -O-, -N- or -S-, and at least one hydrogen atom of the C3-C12 alicyclic hydrocarbon group may be substituted with an isocyanate group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group, or may be substituted with an isocyanate group, a halogen atom, a C1 or C2 alkyl group, and / or a C1-C6 alkoxy group.

[0069] (2) Examples of alicyclic hydrocarbon groups having 3 to 12 carbon atoms and including an alicyclic structure having 3 to 6 carbon atoms, which have at least one isocyanate group, include R in formula (I) which further has at least one isocyanate group. 3 The basis for this can be found in the above-mentioned points.

[0070] R in equation (II) 5 However, in the case of a phenyl group having at least one isocyanate group, at least one carbon atom of the phenyl group may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom may be substituted with an isocyanate group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group. A group in which at least one hydrogen atom of the phenyl group is substituted with an isocyanate group, at least one hydrogen atom, particularly the para hydrogen atom, is substituted with a C1-C4 (preferably 1 or 2) alkyl group, and the hydrogen atom of the C1-C4 alkyl group is substituted with a halogen atom is preferred in terms of easily improving other properties of the piezoelectric material, such as elongation and flexibility.

[0071] A phenyl group in which at least one hydrogen atom of the phenyl group may be substituted with an isocyanate group, a halogen atom, a C1-C4 alkyl group, and / or a C1-C6 alkoxy group, etc., may also be a group in which at least one hydrogen atom is substituted with an isocyanate group and a halogen atom. 5 When this group is present, it is easier to improve other properties of the piezoelectric material, such as its elongation and flexibility.

[0072] R in equation (II) 5 However, if (4) a phenylalkylene group having at least one isocyanate group and including a C1-C4 alkylene group, then at least one carbon atom of the alkylene group may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the phenyl group may be substituted with an isocyanate group, a halogen atom, a C1-C4 alkyl group, a C1-C6 alkoxy group, and / or a cyano group.

[0073] A phenylalkylene group having a hydroxyl group, in which at least one carbon atom of the alkylene group is substituted with -O-, is one which further has at least one isocyanate group, as in formula (I) R 3 The basis for this can be found in the above-mentioned points.

[0074] In formula (II), m2 and n2 are the group R in formula (II) that is contained in the (meth)acrylic polymer represented by formula (II). 5 A constituent unit M2 having and the base R in formula (II) 6This represents the number of repeating constituent units N2, the number of moles of constituent units M2 and N2 contained in the (meth)acrylic polymer, and the number of moles of constituent units N2. m2 is an integer of 1 or more, and n2 is 0 or an integer of 1 or more. The ratio of the total number of moles of constituent units M2 and N2 to the total number of moles of all constituent units contained in the (meth)acrylic polymer (the ratio of the total of m2 and n2 to the total number of constituent units) is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, particularly preferably 90% or more, and particularly more preferably 95% or more, from the viewpoint of compatibility. The upper limit of this ratio is 100% or less.

[0075] The (meth)acrylic polymer represented by formula (II) contains the group R in formula (II). 5 The ratio of the number of moles of constituent unit M2 to the total number of moles of constituent unit M2 and constituent unit N2 contained in the (meth)acrylic polymer is preferably 70% or more, more preferably 80% or more, even more preferably 85% or more, even more preferably 90% or more, particularly preferably 95% or more, particularly more preferably 98% or more, and very preferably 99% or more, from the viewpoint of the flexibility of the resulting piezoelectric material. The upper limit of this ratio is preferably 99.9% or less, more preferably 99.8% or less, and even more preferably 99.7% or less, from the viewpoint of the elasticity of the resulting piezoelectric material. The above ratio is calculated using the formula m2 / (m2+n2)×100.

[0076] In one preferred embodiment of the present invention, the (meth)acrylic polymer represented by formula (II) is R in formula (II). 4 , R 5 and R 6 However, it is a polymer that represents the following group: R 4 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. R 5This represents a linear or branched alkyl group having 1 to 10 carbon atoms and having at least one isocyanate group, preferably a linear or branched alkyl group having 1 to 10 carbon atoms and having one isocyanate group. R 6 This represents a linear or branched alkyl group having 1 to 10 carbon atoms. Here, R 2 The alkyl group in the above may have at least one carbon atom substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the alkyl group may be substituted with an isocyanate group, a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group. R 3 In the alkyl group, at least one carbon atom may be substituted with -O-, -N-, or -S-, and at least one hydrogen atom of the alkyl group may be substituted with a halogen atom, a C1-C6 alkyl group, and / or a C1-C6 alkoxy group.

[0077] When polymer (b) contained in the piezoelectric material composition of the present invention is an isocyanate group-containing polymer (b2), the isocyanate content (NCO content) of the isocyanate group-containing polymer (b2) is preferably 0.01% or more and 35% or less. The NCO content of the hydroxyl group-containing polymer (b1) is more preferably 3% or more and 30% or less, and even more preferably 6% or more and 25% or less. The NCO content of the isocyanate group-containing polymer (b2) may be calculated from the structure of the isocyanate group-containing polymer (b2), or it may be determined in accordance with JIS K 1603-1:2007 or the like.

[0078] (Other constituent units) Polymer (b) may contain other structural units in addition to structural units having hydroxyl groups or isocyanate groups. Examples of other structural units include those derived from carboxyl group-containing monomers, amide group-containing monomers, aryl group-containing monomers, styrene monomers, nitrogen atom-containing monomers, fatty acid vinyl ester monomers, betaine monomers, and the like.

[0079] Examples of carboxyl group-containing monomers include (meth)acrylic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and crotonic acid.

[0080] Examples of monomers containing an amide group include alkyl(meth)acrylamides in which the alkyl group has 1 to 8 carbon atoms, such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N-octyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)acrylamide.

[0081] Examples of aryl group-containing monomers include aryl (meth)acrylates, such as benzyl (meth)acrylate, in which the aryl group has 6 to 12 carbon atoms.

[0082] Examples of styrene monomers include styrene and α-methylstyrene.

[0083] Examples of nitrogen atom-containing monomers include N-vinylpyrrolidone and N-vinylcaprolactam.

[0084] Examples of fatty acid vinyl ester monomers include vinyl acetate and vinyl propionate.

[0085] Examples of betaine monomers include N-acryloyloxymethyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-methacryloyloxymethyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-acryloyloxymethyl-N,N-dimethylammoniumethyl-α-sulfobetaine, N-methacryloyloxymethyl-N,N-dimethylammoniumethyl-α-sulfobetaine, N-acryloyloxymethyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, and N-meth Cryloyloxymethyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-acryloyloxymethyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, N-methacryloyloxymethyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammonium Monium ethyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammonium ethyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammonium butyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammonium butyl-α-sulfobetaine, N -Acryloyloxypropyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-methacryloyloxypropyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-acryloyloxypropyl-N,N-dimethylammoniumethyl-α-sulfobetaine, N-methacryloyloxypropyl-N,N-dimethylammoniumethyl-α-sulfobetaine, N-acryloyloxypropyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-methacryloyloxypropyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-acryloyloxypropyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, N-methacryloyloxypropyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-methacryloyloxybutyl-N,N-dimethylammoniummethyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammoniumethyl-α-sulfobetaine, N-methacryloyloxybutyl-N,N-dimethylammoniumethyl-α-sulfobetaine Examples include sulfobetaine monomers such as N-(meth)acryloyloxyalkyl-N,N-dimethylammoniumalkyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-methacryloyloxybutyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, and N-methacryloyloxybutyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, as well as other N-(meth)acryloyloxyalkyl-N,N-dimethylammoniumalkyl-α-sulfobetaine.

[0086] (Isocyanate group-containing crosslinking agent (c1)) The isocyanate group-containing crosslinking agent (c1) is a component that reacts with the hydroxyl groups of the hydroxyl group-containing polymer (b1) and acts as a crosslinking agent. It is either a polyisocyanate having two or more isocyanate groups (-N=C=O) or a blocked polyisocyanate having two or more blocked isocyanate groups. Examples of polyisocyanates and blocked polyisocyanates are not particularly limited, and those commonly used in the production of urethane resins may be used. The isocyanate content (NCO content) of the isocyanate group-containing crosslinking agent (c1) is preferably 0.01% to 35%. More preferably, the NCO content of the isocyanate group-containing crosslinking agent (c1) is 3% to 30%, and even more preferably 6% to 25%. The NCO content of the isocyanate group-containing crosslinking agent (c1) may be calculated from the structure of the isocyanate group-containing crosslinking agent (c1), or it may be determined in accordance with JIS K 1603-1:2007, etc.

[0087] Examples of polyisocyanates include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, and aromatic triisocyanates. Examples of aliphatic diisocyanates include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Examples of alicyclic diisocyanates include dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate. Examples of aromatic diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, p-phenylene diisocyanate, and naphthylene diisocyanate. Examples of aromatic triisocyanates include triphenylmethane-4,4',4'-triisocyanate, 1,3,5-triisocyanatebenzene, and 2,4,6-triisocyanatetoluene. Among these, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and / or isophorone diisocyanate (IPDI) are preferred. Polyisocyanates may be used individually or in combination of two or more of these types.

[0088] Commercially available polyisocyanates may be used as the polyisocyanate. Examples of commercially available polyisocyanates include the Duranate® series from Asahi Kasei Chemicals and "Bronate 1901" from Daiei Sangyo Co., Ltd. These products may be used individually or in combination of two or more.

[0089] Examples of blocked polyisocyanates include compounds in which the isocyanate groups of the above-mentioned polyisocyanates are protected by reaction with a blocking agent. Here, the blocked isocyanate group is not particularly limited as long as it is a group that is stable at room temperature but can generate an isocyanate group by heating, for example, a group in which an isocyanate group is protected by reaction with a blocking agent. From the viewpoint of ease of deprotection, ease of urethane structure formation, and bringing the temperature close to that of crystallization of the fluorine polymer (a), it is preferable that the blocked isocyanate group is a group that generates an isocyanate group by heating at 40 to 150°C.

[0090] Blocked polyisocyanates are compounds in which the isocyanate group of the above-mentioned polyisocyanate is protected by reaction with a blocking agent. Examples of blocking agents include oxime compounds, lactam compounds, phenol compounds, alcohol compounds, amine compounds, activated methylene compounds, pyrazole compounds, mercaptan compounds, imidazole compounds, and imide compounds. Among these, blocking agents selected from oxime compounds, lactam compounds, phenol compounds, alcohol compounds, amine compounds, activated methylene compounds, and pyrazole compounds are preferred. Specific examples of blocked polyisocyanates are those described in paragraphs

[0144] to

[0146] of Japanese Patent Application Publication No. 2014-238438.

[0091] Commercially available products may be used as blocked polyisocyanates. Examples of commercially available products include hexamethylene diisocyanate-based blocked isocyanates (e.g., Duranate SBN-70D, SBB-70P, SBF-70E, TPA-B80E, 17B-60P, MF-B60B, E402-B80B, MF-K60B, and WM44-L70G from Asahi Kasei Corporation, Takenate B-882N from Mitsui Chemicals, Inc., and 7960, 7961, 7982, 7991, and 7992 from Baxenden, etc.), tolylene diisocyanate-based blocked isocyanates (e.g., Takenate B-830 from Mitsui Chemicals, Inc.), and 4,4'-diph Examples include phenylmethane diisocyanate-based blocked isocyanates (e.g., Takenate B-815N from Mitsui Chemicals, Inc., Bronate PMD-OA01 and PMD-MA01 from Daiei Sangyo Co., Ltd.), 1,3-bis(isocyanatemethyl)cyclohexane-based blocked isocyanates (e.g., Takenate B-846N from Mitsui Chemicals, Inc., Coronate BI-301, 2507 and 2554 from Tosoh Corporation), and isophorone diisocyanate-based blocked isocyanates (e.g., 7950, 7951 and 7990 from Baxenden).

[0092] When the crosslinking agent (c) contained in the piezoelectric material composition of the present invention is an isocyanate group-containing crosslinking agent (c1), the isocyanate content (NCO content) of the isocyanate group-containing crosslinking agent (c1) is preferably 0.01% or more and 35% or less. More preferably, the NCO content of the isocyanate group-containing crosslinking agent (c1) is 3% or more and 30% or less, and even more preferably 6% or more and 25% or less. The NCO content of the isocyanate group-containing crosslinking agent (c1) may be calculated from the structure of the isocyanate group-containing crosslinking agent (c1), or it may be determined in accordance with JIS K 1603-1:2007 or the like.

[0093] (Hydroxygroup-containing crosslinking agent (c2)) The hydroxyl group-containing crosslinking agent (c2) is a component that reacts with the isocyanate groups of the isocyanate group-containing polymer (b2) and acts as a crosslinking agent, and is a polyol having two or more hydroxyl groups. The polyol is not particularly limited and may be one that is commonly used in the manufacture of urethane resins. Examples of polyols include aliphatic polyols and aromatic polyols. The number of hydroxyl groups in the hydroxyl group-containing crosslinking agent (c2) is preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3.

[0094] When the crosslinking agent (c) contained in the piezoelectric material composition of the present invention is a hydroxyl group-containing crosslinking agent (c2), it is preferable that the hydroxyl group-containing crosslinking agent (c2) has a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. The hydroxyl value of the hydroxyl group-containing crosslinking agent (c2) is more preferably 0.1 mg KOH / g or more and 90 mg KOH / g or less, and even more preferably 0.2 mg KOH / g or more and 80 mg KOH / g or less. In one embodiment of the present invention, the hydroxyl value of the hydroxyl group-containing crosslinking agent (c2) may be even more preferably 50 mg KOH / g or less, 30 mg KOH / g or less, 20 mg KOH / g or less, 10 mg KOH / g or less, 5 mg KOH / g or less, etc. The hydroxyl value of the hydroxyl group-containing crosslinking agent (c2) can be determined in the same manner as the hydroxyl group-containing polymer (b1).

[0095] (Method for producing polymer (b)) The polymer (b) contained in the piezoelectric material composition of the present invention can usually be obtained by polymerizing monomer components. Examples of methods for polymerizing monomer components include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization, but the present invention is not limited to these examples. Of these polymerization methods, bulk polymerization and solution polymerization are preferred from the viewpoint of the manufacturability of polymer (b).

[0096] A solvent is used when polymerizing monomer components by solution polymerization. A non-aqueous organic solvent is preferred. Examples of non-aqueous organic solvents include hydrocarbon organic solvents such as hexane, heptane, octane, isooctane, decane, and liquid paraffin; ether organic solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran; ketone organic solvents such as acetone and methyl ethyl ketone; ester organic solvents such as methyl acetate, ethyl acetate, butyl acetate, and γ-butyrolactone; chloride organic solvents such as methylene chloride, chloroform, and carbon tetrachloride; and dimethylformamide, diethylformamide, dimethyl sulfoxide, and dioxane. However, the present invention is not limited to these examples. These organic solvents may be used individually or in combination of two or more. The amount of solvent varies depending on the type of solvent and cannot be generally limited, but it is usually preferably about 100 to 1000 parts by mass per 100 parts by mass of monomer component.

[0097] When polymerizing monomer components, polymerization initiators can be used. Examples of polymerization initiators include photopolymerization initiators and thermal polymerization initiators. Among these polymerization initiators, photopolymerization initiators are preferred from the viewpoint of not leaving a thermal history in polymer (b). Examples of polymerization initiators include 2,2'-azobisisobutyronitrile, methyl azoisobutyrate, azobisdimethylvaleronitrile, benzoyl peroxide, potassium persulfate, ammonium persulfate, benzophenone derivatives, phosphine oxide derivatives, benzoketone derivatives, phenylthioether derivatives, azide derivatives, diazo derivatives, and disulfide derivatives, and two or more may be used in combination if desired.

[0098] Examples of photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,1'-biimidazole, 2,4,6-tris(trichloromethyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(p-methoxyphenylvinyl)-1,3,5-triazine, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, and 4,4'-ditert-butyldiphosphate. Phenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, benzoin, 2-hydroxy-2-methyl-1-phenylpropan-2-one, benzophenone, thioxanthone, 2,4,6-trimethylbenzoyldiphenylacylphosphine oxide, triphenylbutylborate tetraethylammonium, diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, 2,2-dimethoxy-1,2-diphenylethane-1-one, phenyl Photoradical polymerization initiators such as rioxylic acid methyl ester, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1,2-octanedione, 1-[4-(phenylthio)-2-(o-benzoyloxime)], bis(η5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrole-1-yl)phenyltitanium], 2,4,6-tris(trichloromethyl)-1, Examples of photocationic ring-opening polymerization initiators include 3,5-triazine, 2,4-bis(trichloromethyl)-6-(p-methoxyphenylvinyl)-1,3,5-triazine, diphenyliodonium tetrafluoroborate, 4,4'-ditert-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, and diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, but the present invention is not limited to these examples.These photopolymerization initiators may be used individually or in combination of two or more.

[0099] Examples of thermal polymerization initiators include azo polymerization initiators such as dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobisisobutyronitrile (AIBN), dimethyl 2,2'-azobisisobutyrate, and azobisdimethylvaleronitrile, as well as peroxide polymerization initiators such as benzoyl peroxide, potassium persulfate, and ammonium persulfate. However, the present invention is not limited to these examples. These polymerization initiators may be used individually or in combination of two or more.

[0100] The amount of polymerization initiator varies depending on the type of polymerization initiator and cannot be determined definitively, but it is generally preferable to use about 0.01 to 20 parts by mass per 100 parts by mass of monomer component.

[0101] When polymerizing monomer components, chain transfer agents can be used to adjust the molecular weight of the resulting polymer. Examples of chain transfer agents include compounds having thiol groups such as lauryl mercaptan, dodecyl mercaptan, and thioglycerol; and inorganic salts such as sodium hypophosphate and sodium bisulfite. However, the present invention is not limited to these examples. These chain transfer agents may be used individually or in combination of two or more. The amount of chain transfer agent varies depending on the type of chain transfer agent and cannot be determined in general terms, but it is generally preferable to use about 0.01 to 10 parts by mass per 100 parts by mass of monomer component.

[0102] The atmosphere used for polymerizing the monomer components is not particularly limited and may be in the air, or in an inert gas atmosphere such as nitrogen gas or argon gas.

[0103] The temperature for polymerizing the monomer components is not particularly limited, but is generally preferably around 5 to 100°C. The time required for polymerizing the monomer components varies depending on the polymerization conditions and cannot be determined definitively, so it is arbitrary, but is usually around 1 to 20 hours.

[0104] The polymerization reaction can be terminated at will when the amount of remaining monomer components becomes 20% by mass or less. The amount of remaining monomer components can be measured, for example, using gel permeation chromatography.

[0105] By polymerizing the monomer components in the manner described above, polymer (b) contained in the piezoelectric material composition of the present invention can be obtained.

[0106] [Fluorine-based polymer (a)] The piezoelectric material composition of the present invention contains a fluorine polymer (a) in addition to the polymer (b) and crosslinking agent (c) described above. The fluorine polymer is a homopolymer or copolymer of fluorine monomers, and examples of the fluorine polymer (a) include homopolymers of fluorine monomers such as polyvinylidene fluoride, polyvinyl fluoride, polytetrafluoroethylene, and polychlorotrifluoroethylene; copolymers of two or more monomers selected from the group consisting of vinylidene fluoride monomer, hexafluoropropylene monomer, trifluoroethylene monomer, tetrafluoroethylene monomer, and perfluoro(alkyl vinyl ether) monomer; and ethylene-tetrafluoroethylene copolymers. The piezoelectric material composition of the present invention may contain one type of fluorine polymer (a) or two or more types of fluorine polymers (a).

[0107] The weight-average molecular weight of the fluorine polymer (a) contained in the piezoelectric material composition of the present invention is not particularly limited, but from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material, it is preferably 100,000 or more, more preferably 150,000 or more, even more preferably 180,000 or more, even more preferably 200,000 or more, and particularly preferably 300,000 or more. The upper limit of the weight-average molecular weight is not particularly limited, for example, it is about 2,000,000 or less, preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 500,000 or less. The weight-average molecular weight can be measured by known methods.

[0108] The fluorine-based polymer (a) is preferably a vinylidene fluoride polymer, more preferably a polymer selected from the group consisting of polyvinylidene fluoride and vinylidene fluoride / trifluoroethylene copolymers, and even more preferably a vinylidene fluoride / trifluoroethylene copolymer.

[0109] Fluorine-based polymers (a) are good at improving the piezoelectric properties of piezoelectric materials (for example, the piezoelectric constant d 31 ya d 33 From the viewpoint of easily increasing [a certain property], a vinylidene fluoride polymer is preferred. A vinylidene fluoride polymer is a polymer that contains at least one constituent unit derived from vinylidene fluoride, and may be polyvinylidene fluoride, which is a homopolymer of vinylidene fluoride, or a copolymer of vinylidene fluoride and another monomer copolymerizable with vinylidene fluoride.

[0110] Other monomers copolymerizable with vinylidene fluoride include, for example, hexafluoropropylene monomer, trifluoroethylene monomer, tetrafluoroethylene monomer, and perfluoro(alkyl vinyl ether) monomer.

[0111] The amount of constituent units derived from vinylidene fluoride in the vinylidene fluoride polymer is preferably 55 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and may be 80 mol% or more, or even 85 mol% or more, based on the total amount of constituent units, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material and easily obtaining a piezoelectric material with good heat resistance and deformation resistance. Furthermore, the upper limit of the amount of said constituent units is 100 mol% or less.

[0112] In a preferred embodiment of the present invention, the fluorine polymer (a) is a vinylidene fluoride / trifluoroethylene copolymer. The copolymer comprises at least constituent units derived from vinylidene fluoride and constituent units derived from trifluoroethylene. The amount of constituent units derived from vinylidene fluoride in the vinylidene fluoride / trifluoroethylene copolymer is likely to improve the piezoelectric properties of the piezoelectric material (for example, the piezoelectric constant d 31 ya d 33 From the viewpoint of easily improving the piezoelectric properties of the piezoelectric material, as well as obtaining a piezoelectric material with good heat resistance and deformation resistance, the amount of the total constituent units is preferably 55 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and may be 80 mol% or more, or even more preferably 85 mol% or more. Furthermore, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material, the amount of constituent units derived from vinylidene fluoride is preferably 90 mol% or less, more preferably 86 mol% or less, based on the amount of the total constituent units.

[0113] In the vinylidene fluoride / trifluoroethylene copolymer, the amount of constituent units derived from trifluoroethylene is preferably 10 mol% or more, more preferably 14 mol% or more, based on the total amount of constituent units, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material. Furthermore, from the viewpoint of obtaining a piezoelectric material with good heat resistance, the amount of constituent units derived from trifluoroethylene is preferably 45 mol% or less, more preferably 30 mol% or less, even more preferably 25 mol% or less, and particularly preferably 20 mol% or less, based on the total amount of constituent units.

[0114] When the fluorine polymer (a) contained in the piezoelectric material composition of the present invention is a vinylidene fluoride / trifluoroethylene copolymer, the copolymer may contain, in addition to the constituent units derived from vinylidene fluoride and the constituent units derived from trifluoroethylene, constituent units derived from other monomers that can copolymerize with vinylidene fluoride and / or trifluoroethylene, to the extent that it does not impair the effects of the present invention. From the viewpoint of easily obtaining a piezoelectric material with excellent heat resistance and piezoelectric properties, the content of constituent units derived from vinylidene fluoride and the constituent units derived from trifluoroethylene in the vinylidene fluoride / trifluoroethylene copolymer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, particularly preferably 93% by mass or more, and most preferably 95% by mass or more, and the content of constituent units derived from other monomers that can copolymerize with vinylidene fluoride and / or trifluoroethylene is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, particularly preferably 7% by mass or less, and most preferably 5% by mass or less. Furthermore, the content of constituent units derived from vinylidene fluoride and constituent units derived from trifluoroethylene in the vinylidene fluoride / trifluoroethylene copolymer may be 100% by mass or less, 99% by mass or less, 98% by mass or less, or 97% by mass or less, and the content of constituent units derived from other monomers that can copolymerize with vinylidene fluoride and / or trifluoroethylene may be 1% by mass or more, 2% by mass or more, or 3% by mass or more.

[0115] The fluorine-based polymer included in the piezoelectric material composition of the present invention may be one with the composition and molecular weight shown in, for example, Patent Document 1, or a commercially available one may be used. Examples of commercially available vinylidene fluoride / trifluoroethylene copolymers include, for example, "FC20," "FC25," and "FC30" manufactured by PIEZOTECH. Examples of commercially available vinylidene fluoride polymers include, for example, "Poly(vinylidene fluoride)" from Sigma-Aldrich and "KYNAR741" from Arkema.

[0116] [Compositions for piezoelectric materials] The amount of polymer (b) contained in the piezoelectric material composition of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total amount of solids contained in the piezoelectric material composition, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material. Furthermore, from the viewpoint of compatibility, the amount of polymer (b) contained in the piezoelectric material composition of the present invention is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, even more preferably 12% by mass or less, and even more preferably 10% by mass or less.

[0117] The amount of crosslinking agent (c) contained in the piezoelectric material composition of the present invention is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.08% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.15% by mass or more, and may also be 0.2% by mass or more, based on the total amount of solids contained in the piezoelectric material composition, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material. Furthermore, from the viewpoint of the resulting piezoelectric material having high flexibility and stretchability, the amount of crosslinking agent (c) contained in the piezoelectric material composition of the present invention is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.8% by mass or less.

[0118] The amount of fluorine polymer (a) contained in the piezoelectric material composition of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total amount of solids contained in the piezoelectric material composition, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material. Furthermore, the amount of fluorine polymer (a) contained in the piezoelectric material composition of the present invention may be preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, from the viewpoint of easily improving the piezoelectric properties of the piezoelectric material and easily exhibiting the effects of the specific polymer (b) etc.

[0119] The total amount of fluorine-based polymer (a), polymer (b), and crosslinking agent (c) contained in the piezoelectric material composition of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the solid content of the piezoelectric material composition, with an upper limit of 100% by mass or less.

[0120] The amount of fluorine polymer (a) contained in the piezoelectric material composition of the present invention is preferably 60 to 99% by mass, more preferably 70 to 98% by mass, and even more preferably 80 to 97% by mass, based on the total amount of fluorine polymer (a), polymer (b), and crosslinking agent (c).

[0121] The total amount of polymer (b) and crosslinking agent (c) contained in the piezoelectric material composition of the present invention is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, and even more preferably 1 to 20%, based on the total amount of fluorine polymer (a), polymer (b), and crosslinking agent (c).

[0122] When the piezoelectric material composition of the present invention contains a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), the equivalent ratio (hydroxyl group:isocyanate group) of the hydroxyl groups of the hydroxyl group-containing polymer (b1) and the isocyanate groups of the isocyanate group-containing crosslinking agent (c1) contained in the composition is preferably 0.5:1.5~1.5:0.5, more preferably 0.7:1.3~1.3:0.7, even more preferably 0.8:1.2~1.2:0.8, and even more preferably 0.9:1.1~1.1:0.9, from the viewpoint of promoting the crosslinking reaction.

[0123] When the piezoelectric material composition of the present invention contains a hydroxyl group-containing crosslinking agent (c2) and an isocyanate group-containing polymer (b2), the equivalent ratio (hydroxyl group:isocyanate group) of the hydroxyl groups of the hydroxyl group-containing crosslinking agent (c2) and the isocyanate groups of the isocyanate group-containing polymer (b2) contained in the composition is preferably 0.5:1.5~1.5:0.5, more preferably 0.7:1.3~1.3:0.7, even more preferably 0.8:1.2~1.2:0.8, and even more preferably 0.9:1.1~1.1:0.9, from the viewpoint of promoting the crosslinking reaction.

[0124] The structure and amount of the fluorine-based polymer (a), polymer (b), and crosslinking agent (c) contained in the piezoelectric material composition of the present invention can be analyzed using, for example, an infrared spectrometer (IR), a nuclear magnetic resonance spectrometer (NMR), etc., but are not limited thereto. These amounts may also be calculated from the raw material charging ratio. The same applies to the fluorine-based polymer (a) and crosslinking polymer (d) contained in the piezoelectric material of the present invention. For example, after determining the structure of the fluorine-based polymer (a) and the crosslinking polymer (d) contained in the piezoelectric material, they may be separated from the piezoelectric material by known methods, or polymers with the same structure may be prepared and analyzed by the analytical methods described above to analyze the structure and amount of the fluorine-based polymer (a) and crosslinking polymer (d) constituting the piezoelectric material.

[0125] The piezoelectric material composition of the present invention may contain materials other than the fluorine polymer (a), polymer (b), and crosslinking agent (c) (hereinafter referred to as "other materials"). Examples of other materials include, but are not limited to, further polymers described later (e.g., polymer (e) described later), crosslinking accelerators, solvents, polymers and elastomers other than the fluorine polymer (a) and polymer (b), additives such as antioxidants, ultraviolet absorbers, and surface modifiers (surfactants), thermally conductive fillers, and conductive fillers. One of these components may be further included, or two or more may be included in combination.

[0126] Examples of additional polymers that can be included in the composition for piezoelectric materials include other polymers different from the fluoropolymer (a) and the polymer (b), for example, polymers having a halogen atom (also referred to as polymer (e)). As the polymer (e), represented by the following formula (e) as described in International Publication No. WO 2021 / 210426:

Chemical Formula

[0127] The crosslinking accelerator that may be included in the piezoelectric material composition is preferably a crosslinking accelerator that can promote the crosslinking reaction between a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1) that forms urethane bonds, or between an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2). Examples of such crosslinking accelerators include known crosslinking agents used in the production of urethane polymers, such as amine-based catalysts such as imidazole compounds and piperazine compounds, and metal-based catalysts. Examples of commercially available crosslinking accelerators include the Orgatics series manufactured by Matsumoto Fine Chemical Co., Ltd., such as Orgatics 150 and Neostan U-100. If the piezoelectric material composition further contains a crosslinking accelerator, its content is preferably 0.0005 to 10% by mass, more preferably 0.001 to 1% by mass, and even more preferably 0.01 to 0.5% by mass, based on the solid content of the piezoelectric material composition.

[0128] The solvents that may be included in the piezoelectric material composition are not particularly limited as long as they can dissolve the fluorine polymer (a), the polymer (b), and the crosslinking agent (c), but examples include N,N-dimethylformamide, N,N-dimethylacetamide, 1-methyl-2-pyrrolidone, diethyl carbonate, dimethyl carbonate, butyl acetate, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, etc.

[0129] A piezoelectric material composition of the present invention, in a preferred embodiment of the present invention, (1) A piezoelectric material composition comprising at least one component, comprising an agent containing a fluorine polymer (a), a polymer (b), and a crosslinking agent (c), (2) A piezoelectric material composition comprising at least two components, comprising a first component containing a fluorine polymer (a) and a polymer (b), and a second component containing a crosslinking agent (c), (3) A two-component piezoelectric material composition comprising a first component containing a fluorine polymer (a) and a crosslinking agent (c), and a second component containing a polymer (b), or (4) A piezoelectric material composition comprising at least three components: a first component containing a fluorine polymer (a), a second component containing a polymer (b), and a third component containing a crosslinking agent (c).

[0130] If the crosslinking agent (c) is an isocyanate group-containing crosslinking agent (c1), and the isocyanate group-containing crosslinking agent (c1) is a blocked polyisocyanate, the piezoelectric material composition of the present invention may be any of (1) to (4) above. Also, if the polymer (b) is an isocyanate group-containing polymer (b2), and the isocyanate group is protected with a blocking agent, the piezoelectric material composition of the present invention may be any of (1) to (4) above.

[0131] In one embodiment of the present invention, where the crosslinking agent (c) is an isocyanate group-containing crosslinking agent (c1) and the isocyanate group is not protected by a blocking agent, it is preferable that the piezoelectric material composition of the present invention be manufactured by preparing the hydroxyl group-containing polymer (b1) and the isocyanate group-containing crosslinking agent (c1) as separate agents and mixing them immediately before use, from the viewpoint of easily improving the storage stability of the composition. From this viewpoint, in this embodiment, it is preferable that the piezoelectric material composition of the present invention be any of (2) to (4) above, from the viewpoint of easily improving the storage stability of the composition.

[0132] In another embodiment of the present invention, where polymer (b) is an isocyanate group-containing polymer (b2) and the isocyanate group is not protected by a blocking agent, it is preferable that the piezoelectric material composition of the present invention be prepared by manufacturing the isocyanate group-containing polymer (b2) and the hydroxyl group-containing crosslinking agent (c2) separately and mixing them immediately before use, from the viewpoint of easily improving the storage stability of the composition. From this viewpoint, in this embodiment, it is preferable that the piezoelectric material composition of the present invention be any of (2) to (4) above, from the viewpoint of easily improving the storage stability of the composition.

[0133] The piezoelectric material composition of the present invention can be produced by mixing a fluorine-based polymer (a), a polymer (b), and a crosslinking agent (c) together with other components, such as a solvent, as is sometimes the case.

[0134] The piezoelectric material composition of the present invention is not particularly limited, but for example, it may be produced by mixing a fluorine polymer (a), a polymer (b), and a crosslinking agent (c), and optionally a solvent, while heating as needed, to dissolve the fluorine polymer (a), polymer (b), and crosslinking agent (c) in the solvent. Alternatively, some of these components may be made into a separate composition, resulting in a two-part or more formulation. Furthermore, the form of the piezoelectric material composition is not limited to a liquid, and in particular, in the case of a two-part or more formulation, at least one of the components may be a solid such as a pellet or film.

[0135] [Piezoelectric materials] The piezoelectric material of the present invention can be manufactured using the piezoelectric material composition of the present invention. The present invention also provides a piezoelectric material formed from the piezoelectric material composition of the present invention.

[0136] The piezoelectric material of the present invention is a piezoelectric material containing a fluorine-based polymer (a) and a crosslinked polymer (d) containing a urethane bond, and is preferably formed from the piezoelectric material composition of the present invention.

[0137] The crosslinked polymer (d) containing urethane bonds is not particularly limited as long as it is a polymer that contains urethane bonds in the crosslinked structure portion, but it is preferably a polymer that contains at least a structure derived from polymer (b) described in relation to the piezoelectric material composition of the present invention and a structure derived from the crosslinking agent (c). In one preferred embodiment, the polymer containing at least a structure derived from polymer (b) and a structure derived from the crosslinking agent (c) is a reaction product of a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and in another preferred embodiment, it is a reaction product of an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2). In either case, the urethane bonds in the crosslinked polymer (d) are formed by the reaction of hydroxyl groups and isocyanate groups.

[0138] The total amount of fluorine-based polymer (a) and crosslinked polymer (d) contained in the piezoelectric material of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total amount of piezoelectric material, with an upper limit of 100% by mass or less.

[0139] The amount of fluorine polymer (a) contained in the piezoelectric material of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total amount of piezoelectric material, from the viewpoint of easily enhancing the piezoelectric properties of the piezoelectric material. Furthermore, the amount of fluorine polymer contained in the piezoelectric material of the present invention may be preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, from the viewpoint of easily increasing the residual polarization of the piezoelectric material and easily exhibiting the effects of the crosslinked polymer (d).

[0140] The amount of crosslinked polymer (d) contained in the piezoelectric material of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, based on the total amount of piezoelectric material, from the viewpoint of tensile stress and elongation, and from the viewpoint of piezoelectricity, preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, particularly preferably 10% by mass or less, and most preferably 5% by mass or less, based on the total amount of piezoelectric material.

[0141] The amount of fluorine polymer (a) contained in the piezoelectric material of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total amount of fluorine polymer (a) and crosslinked polymer (d), from the viewpoint of easily enhancing the piezoelectric properties of the piezoelectric material. Furthermore, the amount of fluorine polymer contained in the piezoelectric material of the present invention may be preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, based on the total amount of fluorine polymer (a) and crosslinked polymer (d), from the viewpoint of easily enhancing the piezoelectric properties of the piezoelectric material and easily exhibiting the effects of crosslinked polymer (d).

[0142] The amount of crosslinked polymer (d) contained in the piezoelectric material of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, based on the total amount of fluorine polymer (a) and crosslinked polymer (d) from the viewpoint of tensile stress and elongation, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, particularly preferably 10% by mass or less, and most preferably 5% by mass or less, based on the total amount of fluorine polymer (a) and crosslinked polymer (d).

[0143] The method for manufacturing the piezoelectric material of the present invention is not particularly limited, and an appropriate method can be selected depending on the shape and application of the piezoelectric material to be manufactured. For example, the piezoelectric material may be manufactured by applying the piezoelectric material composition of the present invention, drying it, and then heat-treating it to crystallize the fluorine polymer (a) to generate piezoelectric properties. Another example is a method for manufacturing a piezoelectric material that includes the steps of mixing a fluorine polymer (a), a monomer constituting a polymer (b), a crosslinking agent (c), and a solvent if necessary; polymerizing the monomer to obtain a polymer (b); and crystallizing the fluorine polymer and causing a crosslinking reaction between the polymer (b) and the crosslinking agent (c) to generate piezoelectric properties. Another example is a method for manufacturing a piezoelectric material that includes the steps of mixing a polymer (b), a crosslinking agent (c), a monomer constituting a fluorine polymer, and a solvent if necessary; polymerizing the monomer to obtain the fluorine polymer; and crystallizing the fluorine polymer and causing a crosslinking reaction between the polymer (b) and the crosslinking agent (c) to generate piezoelectric properties.

[0144] The piezoelectric material of the present invention can be manufactured by applying the piezoelectric material composition of the present invention to a substrate, drying it, and then crystallizing it by heat treatment to generate piezoelectric properties. Here, for example, in the drying step and / or the crystallization step by heat treatment described above, the polymer (b) and the crosslinking agent (c) are heated to a temperature at which a crosslinking reaction occurs, or a separate crosslinking step by heat treatment is performed, thereby causing a crosslinking reaction between the polymer (b) and the crosslinking agent (c) to form a crosslinked polymer (d) containing urethane bonds. From the viewpoint of efficiently manufacturing piezoelectric materials, it is preferable to perform the crosslinking reaction simultaneously in the crystallization step by heat treatment.

[0145] For example, if the piezoelectric material of the present invention is a piezoelectric film, the piezoelectric material composition of the present invention may be applied to the surface of a substrate. For example, if the piezoelectric material of the present invention is a piezoelectric wire, the piezoelectric material composition of the present invention may be applied to a conductive wire, such as a copper wire, for example, a single wire made of a conductive material, by a known method.

[0146] The method for drying the applied piezoelectric material composition of the present invention is not particularly limited, and it may be dried by heating at a temperature at which the solvent evaporates under atmospheric pressure or reduced pressure conditions. For example, drying at a temperature of 15 to 80°C is preferred.

[0147] The heat treatment temperature used when manufacturing the piezoelectric material of the present invention is preferably above the Curie point and below the melting point of the fluorine polymer (a). If crosslinking is performed at this stage, it is preferable to perform the heat treatment at a temperature above the temperature at which the crosslinking reaction occurs, for example, 60 to 150°C, preferably 100 to 150°C. The heating time is preferably 30 minutes or more, more preferably 2 hours or more. By performing such heat treatment, the fluorine polymer (a) is crystallized and piezoelectric properties can be exhibited.

[0148] Other examples of methods for manufacturing the piezoelectric material of the present invention include extrusion molding, inflation molding, and injection molding of the piezoelectric material composition.

[0149] The piezoelectric material of the present invention may be a piezoelectric film, a piezoelectric wire, or a piezoelectric block (lump). Because the piezoelectric material of the present invention has a large residual polarization, it can store a large amount of electrical energy per unit volume, making it possible to use it in applications such as sensor components.

[0150] In a preferred embodiment of the present invention, the piezoelectric material of the present invention has not only high piezoelectric properties but also excellent heat resistance. From the viewpoint of easily utilizing the features of the piezoelectric material of the present invention in this embodiment, the piezoelectric material is particularly suitable as a component of sensors such as touch sensors, acceleration sensors, vibration sensors, and ultrasonic sensors, as well as a component of strain gauges and transducers. As a method for evaluating the heat resistance of the piezoelectric material, one method is to measure the 1% weight loss temperature using a differential thermogravimetric simultaneous measurement device. In the above evaluation method, a piezoelectric material having a 1% weight loss temperature of preferably 120°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher, can be said to have particularly excellent heat resistance.

[0151] From the perspective of easily obtaining sufficient piezoelectric properties, the remanent polarization of the piezoelectric material of the present invention is preferably 30 mC / m 2 or more, more preferably 40 mC / m 2 or more, more preferably 50 mC / m 2 or more, more preferably 60 mC / m 2 or more, still more preferably 70 mC / m 2 or more, still more preferably 80 mC / m 2 or more, still more preferably 90 mC / m 2 or more, still more preferably 100 mC / m 2 or more. The higher the remanent polarization, the better. The upper limit thereof is not particularly limited, but may be, for example, 200 mC / m 2 or less. The measurement of remanent polarization may be performed, for example, under conditions where a triangular wave alternating current with a voltage amplitude of 200 MV / m and a frequency of 0.01 Hz or 0.1 Hz is applied.

[0152] The piezoelectric constant d of the piezoelectric material of the present invention 31 , from the perspective of easily obtaining sufficient piezoelectric properties when bending stress or tensile stress is applied to the piezoelectric material, is preferably 13 pC / N or more, more preferably 14 pC / N or more, and still more preferably 15 pC / N or more. The measurement method of the piezoelectric constant d 31 is as described in the Examples.

[0153] The piezoelectric constant d of the piezoelectric material of the present invention 33 , from the perspective of easily obtaining sufficient piezoelectric properties when pressure is applied to the piezoelectric material, is preferably 15 pC / N or more, more preferably 18 pC / N or more, and still more preferably 20 pC / N or more. The measurement method of the piezoelectric constant d 33 is as described in the Examples.

[0154] From the perspective of facilitating the stretchability of the piezoelectric material, when measured using a film cut into a rectangular shape (for example, a rectangle of 5 mm × 60 mm) as a measurement sample, the elongation percentage of the piezoelectric material of the present invention is preferably 5 to 500%, more preferably 10 to 250%, and still more preferably 15 to 100%. The measurement method of elongation percentage is as described in the Examples.

[0155] The hysteresis loss of the piezoelectric material of the present invention is preferably 35% or less, more preferably 32% or less, and even more preferably 30% or less, when measured using a rectangularly cut film (for example, a rectangle of 5 mm x 60 mm) as the measurement sample, from the viewpoint of easily generating elasticity of the piezoelectric material. The method for measuring the hysteresis loss is as described in the examples.

[0156] The Young's modulus of the piezoelectric material of the present invention is preferably 1.5 GPa or less, more preferably 1.3 GPa or less, and even more preferably 1.2 GPa or less, when measured using a rectangularly cut film (for example, a rectangle of 5 mm x 60 mm) as the measurement sample, from the viewpoint of easily improving the elasticity and flexibility of the piezoelectric material. The method for measuring the Young's modulus is as described in the examples. [Examples]

[0157] Next, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and do not limit the present invention in any way. Unless otherwise specified, "%" and "parts" in the examples mean "mass %" and "parts by mass," respectively.

[0158] (Weight average molecular weight) The weight-average molecular weight was measured by gel permeation chromatography (GPC). Specifically, a 0.05-0.1% by mass solution obtained by dissolving fluorinated polymer (a) or polymer (b) in tetrahydrofuran was used as the measurement sample. The measurement conditions were as follows: Equipment: Manufactured by Tosoh Corporation, Part Number: HLC-8320GPC Column: Manufactured by Tosoh Corporation, Part Number: TSKgel GMHHR-H Eluent: Tetrahydrofuran Flow rate: 0.5mL / min Temperature: 40℃ Detector: RI Molecular weight standard: Standard polystyrene

[0159] (Hydroxyl value) Measurements were taken in accordance with JIS K1557.

[0160] [Manufacturing Example 1: Preparation of Polymer (b1)] Ethyl acrylate (manufactured by Toagosei Co., Ltd.) 10.012 parts by mass, 4-hydroxybutyl A monomer component containing a polymerization initiator was obtained by mixing 0.072 parts by mass of acrylic acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) and 0.012 parts by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide [manufactured by BASF, trade name: IrgacureTPO] as a polymerization initiator. The obtained monomer components are molded into a transparent glass mold (length: 100mm, width: 100mm, depth: After injection into a 2mm cavity, the monomer component was irradiated with a dose of 0.60 mW / cm². 2 Tona Polymer (b1) was obtained by irradiating the monomer components with ultraviolet light and allowing them to undergo bulk polymerization for 2 hours. The molar ratio of unit n2 to unit m1 [n2 × 100 / m1] in polymer (b1) was 0.5. The weight-average molecular weight of polymer (b1) was 1,370,000, and the hydroxyl value was 2.8 mgKOH / g.

[0161] [Manufacturing Example 2: Preparation of Polymer (x)] A monomer component containing a polymerization initiator was obtained by mixing 10.012 parts by mass of ethyl acrylate (manufactured by Toagosei Co., Ltd.) and 0.0063 parts by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, trade name: IrgacureTPO) as a polymerization initiator. Polymer (x) was obtained by polymerizing the obtained monomer components in the same manner as in Production Example 1. The weight-average molecular weight of polymer (x) was 2,530,000, and the hydroxyl value was 0 mgKOH / g.

[0162] [Manufacturing Example 3: Preparation of Polymer (e)] (1) Preparation of 3,3,3-trifluoropropyl methacrylate (3FPMA) In a 1 L glass five-necked flask equipped with a reflux condenser, water separator, air inlet tube, thermometer, and stirrer, 25.0 g of 3,3,3-trifluoropropanol, 18.9 g of methacrylic acid, and 5.36 g of N,N-dimethyl-4-aminopyridine were dissolved in 200 g of dichloromethane. 44.1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added while stirring on an ice bath, and stirring was continued for 10 hours. The resulting reaction mixture was washed with water, concentrated, and then purified by vacuum distillation to obtain 21.9 g of 3,3,3-trifluoropropyl methacrylate (3FPMA) as a colorless, transparent liquid (GC purity: 99%, yield: 55%).

[0163] [ka]

[0164] (3FPMA 1 H-NMR (CDCl3, ppm): 1.95(3H,t), 2.44-2.59(2H,m), 4.38(2H,t), 5.58-5.62(1H,m), 6.13-6.14(1H,m)

[0165] (2) Preparation of (meth)acrylic polymer (e) (Poly-3FPMA) 22.1 g of the 3FPMA obtained above was added to a glass container, and 0.22 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide [BASF, trade name: IrgacureTPO] was dissolved as a polymerization initiator to obtain a monomer component containing the polymerization initiator. The monomer components obtained above were injected into a transparent glass mold (length: 100 mm, width: 100 mm, depth: 0.5 mm), and then the monomer components were irradiated with a dose of 1.0 mW / m². 2 p-3FPMA was obtained by irradiating the monomer components with ultraviolet light to induce bulk polymerization. The weight-average molecular weight (Mw) was measured by gel permeation chromatography and found to be 224,000.

[0166] [ka]

[0167] [Example 1: Manufacturing of piezoelectric material composition 1 and piezoelectric material 1] (1-1) A solution was obtained by mixing 25.00 g of vinylidene fluoride / trifluoroethylene copolymer a1 (P(VDF / TrFE)a1, VDF:TrFE = 85:15 (molar ratio), weight-average molecular weight: 435,000) and 175.00 g of cyclopentanone (manufactured by Nippon Zeon Co., Ltd.) as a solvent in a flask and heating at 50°C until dissolved.

[0168] (1-2) 8.07 g of polymer (b1) obtained in Production Example 1, 0.41 g of Duranate MF-K60B (hexamethylene diisocyanate-based blocked isocyanate) as a crosslinking agent (c1-1), 0.0027 g of Orgatic ZC150 as a crosslinking accelerator, and 72.08 g of cyclopentanone as a solvent were mixed in a stoppered flask.

[0169] (1-3) 32.96 g of the solution prepared in (1-1) and 4.51 g of the solution prepared in (1-2) were mixed in a flask to produce piezoelectric material composition 1 in the mass ratio shown in Table 1.

[0170] (1-4) The piezoelectric material composition 1 manufactured as described above was applied to a commercially available glass plate using a commercially available applicator with a gap of 1.0 mm. This was heated at 65°C for 1 hour, then dried at 140°C for 1 hour, and then slowly cooled to room temperature. The thickness of the film was measured to be 40 μm. Next, a resistance heating type vacuum deposition machine (RVC-2-ICP, manufactured by Riken Corporation) was used to deposit the material at an atmospheric pressure of 2 × 10⁻⁶. -4Gold was heated and evaporated at a temperature of Pa or less to form electrodes, thereby obtaining a piezoelectric material composition 1 that also served as an electrode. A triangular wave AC current with an electric field amplitude of 200 MV / m and a frequency of 0.01 Hz was applied between the electrodes of the material thus obtained using a high-voltage device (HEOPS-1B30, manufactured by Matsusada Precision Co., Ltd.) to perform polarization treatment and obtain a piezoelectric material 1. The piezoelectric constant d of piezoelectric material 1 31 and piezoelectric constant d 33 The following methods were used to measure the material. Additionally, Young's modulus, elongation, and hysteresis loss were measured using the following methods. The results are shown in Table 1.

[0171] [Piezoelectric constant d] 31 and d 33 Measurement) Piezoelectric constant d for each piezoelectric material film 31 and d 33 The piezoelectric constant was measured using a piezoelectric constant measuring device (manufactured by Lead Techno, product name: LPF-02). Specifically, the measurements were performed using the following procedure.

[0172] (Piezoelectric constant d) 31 ) (1) The membrane was clamped with the measuring probe so that the measurement length was (8-15 mm). (2) The load applied to the membrane from the measuring probe was set to 1N and left undisturbed. (3) The amount of charge A generated when a force of 1 N was applied was measured. (4) The load applied to the membrane from the measuring probe was increased by 3N, and the load applied to the membrane from the measuring probe was set to 4N. (5) The amount of charge B generated when a force of 4N was applied was measured. (6) The load applied to the membrane from the measuring probe was reduced by 3N to 1N. (7) Repeat steps (3) to (6) above four times. The average of the difference (AB) between the measured charge amounts A and B measured in the 2nd to 4th steps is taken as the charge amount of the film in each example and comparative example. Divide this average charge amount by the evaluation area (film thickness × film length (distance between probes)) and the measurement load (3N) to obtain the piezoelectric constant d of the film in each example and comparative example. 31 The result was calculated.

[0173] (Piezoelectric constant d) 33 ) (1) The membrane was held between the measuring probes. (2) The load applied to the membrane from the measuring probe was set to 1N and left undisturbed. (3) The amount of charge A generated when a force of 1 N was applied was measured. (4) The load applied to the membrane from the measuring probe was increased by 3N, and the load applied to the membrane from the measuring probe was set to 4N. (5) The amount of charge B generated when a force of 4N was applied was measured. (6) The load applied to the membrane from the measuring probe was reduced by 3N to 1N. (7) Repeat steps (3) to (6) above four times. The average of the difference (AB) between the measured charge amounts A and B measured in the 2nd to 4th steps is taken as the charge amount of the film in each example and comparative example. Divide this average charge amount by the measuring load (3N) to obtain the piezoelectric constant d of the film in each example and comparative example. 33 The result was calculated.

[0174] [Measurement of Young's modulus and elongation] Test specimens were obtained by punching out rectangular shapes measuring 5 mm x 60 mm. The obtained test specimens were mounted on a tensile testing machine (manufactured by A&D Co., Ltd., model number: Tensilon RTG-1310) with a chuck distance of 40 mm, and a tensile load was applied at a tensile speed of 5 mm / min until the test specimen broke. The Young's modulus and elongation were measured. The elongation of the film obtained above was calculated using the formula: [Elongation of film (%)] = [Length of test specimen at break (mm) - Original length of test specimen (mm)] ÷ [Original length of test specimen (mm)] × 100. The results are shown in Table 1.

[0175] [Measurement of hysteresis] Regarding hysteresis, we derived a hysteresis loss, which serves as an evaluation index. In detail, using the aforementioned test specimen and tensile testing machine, the following measurements were performed, and the hysteresis loss was calculated using the resulting graph. The measurement consisted of two cycles: applying a tensile load to the test specimen until it reached 12.5% ​​elongation (changing the chuck distance from 40 mm to 45 mm), and then returning the specimen from 12.5% ​​to 0% (returning the chuck distance from 45 mm to 40 mm) (both at 50 mm / min). The hysteresis loss was calculated from the graph of the measurement results from the second cycle. The data was recorded at a retention interval of 0.1 seconds.

[0176] The method for calculating hysteresis loss will be explained in detail using Figure 1. Figure 1 is a graph for illustrating hysteresis loss. The horizontal axis represents film elongation, and the vertical axis represents standardized stress. Standardized stress is the value obtained by dividing the observed stress at each time by the observed stress when the film elongation is 100%. Hysteresis loss was calculated by determining the area of ​​the region enclosed by the dotted line (forward path) and the solid line (return path) in Figure 1. A smaller hysteresis loss indicates better followability. The area was calculated as follows: First, let σA be the stress at strain 1 (film elongation 100%), and then Z be the standardized stress at time t. t The standardized stress Z at time t was calculated based on the following formula: [Z t ]=[stress σ at time t] t (MPa) ÷ [Stress σA (MPa) at strain 1]. Also, the elongation of the film at a certain time t is ε t Let's assume that when time changes from a certain time t-1 to the next time (0.1 seconds later) t, the SS curve, the line Z=0, and the line ε=ε t-1 , line ε = ε t The area enclosed by the triangle was approximated by the area of ​​a trapezoid and calculated using the following formula. [Area S of the trapezoid as time changes from t-1 to t] t ]=( Z t-1 + Z t )×(ε t -ε t-1 )÷2 Finally, S obtained from the start to the end of the second cycle. tThe sum of these values ​​was calculated and defined as the hysteresis loss. The results are shown in Table 1.

[0177] [Examples 2-5 and Comparative Examples 1-7] A piezoelectric material was prepared in the same manner as in Example 1, except that the composition of the piezoelectric material composition was changed to the composition shown in Table 1. The results of the same measurements performed on the obtained piezoelectric material are shown in Table 1. In addition, P(VDF / TrFE)a2 (VDF:TrFE = 80:20 (molar ratio), weight-average molecular weight: 200,000) was used as the vinylidene fluoride / trifluoroethylene copolymer (a2), and hexamethylene diisocyanate was used as the crosslinking agent c1-2.

[0178] [Table 1]

[0179] The piezoelectric materials of the present invention described in Examples 1 to 5 maintain a piezoelectric constant d even without stretching or other treatments. 31 It was confirmed that the piezoelectric material has a high piezoelectric constant and exhibits high piezoelectricity when tensile stress and / or bending stress are applied to it. Furthermore, it is understood that the material is stretchable due to its high elongation and low hysteresis loss. In contrast, the piezoelectric material of the comparative example, which contains copolymer (a) but does not contain the crosslinked polymer (d) of the present invention, has a piezoelectric constant d 31 The material was either not sufficiently elastic, or its hysteresis loss was too high, meaning it could not be considered to have sufficient elasticity.

Claims

1. It contains a fluorine polymer (a), a polymer (b), and a crosslinking agent (c), A piezoelectric material composition wherein the polymer (b) and the crosslinking agent (c) are a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and / or an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2), Fluorine polymer (a) is a vinylidene fluoride polymer, The hydroxyl group-containing polymer (b1) is a (meth)acrylic polymer having a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. The hydroxyl group-containing crosslinking agent (c2) has a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. Polymer (b) is a (meth)acrylic polymer. A composition for piezoelectric materials.

2. A piezoelectric material composition comprising at least one component, comprising an agent containing a fluorine polymer (a), a polymer (b), and a crosslinking agent (c), A piezoelectric material composition comprising at least two components: a first component containing a fluorine polymer (a) and a polymer (b), and a second component containing a crosslinking agent (c), A piezoelectric material composition comprising at least two components, comprising a first component containing a fluorine-based polymer (a) and a crosslinking agent (c), and a second component containing a polymer (b), or This piezoelectric material composition comprises at least three components: a first component containing a fluorine-based polymer (a), a second component containing a polymer (b), and a third component containing a crosslinking agent (c). The piezoelectric material composition according to claim 1.

3. The piezoelectric material composition according to claim 1, wherein the amount of fluorine polymer (a) is 60 to 99% by mass, and the total amount of polymer (b) and crosslinking agent (c) is 1 to 40% by mass, based on the total amount of fluorine polymer (a), polymer (b), and crosslinking agent (c).

4. The piezoelectric material composition according to claim 1, wherein the total amount of the fluorine polymer (a), polymer (b), and crosslinking agent (c) is 80% by mass or more based on the solid content of the piezoelectric material composition.

5. The piezoelectric material composition according to claim 1, wherein the isocyanate group-containing crosslinking agent (c1) is a blocked polyisocyanate.

6. The equivalent ratio (hydroxyl group:isocyanate group) of the hydroxyl group-containing polymer (b1) and the isocyanate group-containing crosslinking agent (c1) is 0.5:1.5 to 1.5:0.

5. The equivalent ratio (hydroxyl group:isocyanate group) of the hydroxyl group-containing crosslinking agent (c2) and the isocyanate group-containing polymer (b2) is 0.5:1.5 to 1.5:0.

5. The piezoelectric material composition according to claim 1.

7. The piezoelectric material composition according to claim 1, wherein the weight-average molecular weight of the fluorine polymer (a) is 100,000 or more.

8. The piezoelectric material composition according to claim 1, wherein the fluorine-based polymer (a) is a vinylidene fluoride / trifluoroethylene copolymer, and the amount of constituent units derived from vinylidene fluoride in the copolymer is 55 to 90 mol% based on the total amount of constituent units.

9. A piezoelectric material formed from a piezoelectric material composition according to any one of claims 1 to 8.

10. A piezoelectric material comprising a fluorine-based polymer (a) and a crosslinked polymer (d) containing a urethane bond, Fluorine polymer (a) is a vinylidene fluoride polymer, The crosslinked polymer (d) comprises at least a structure derived from polymer (b) and a structure derived from crosslinking agent (c), wherein polymer (b) and crosslinking agent (c) are a hydroxyl group-containing polymer (b1) and an isocyanate group-containing crosslinking agent (c1), and / or an isocyanate group-containing polymer (b2) and a hydroxyl group-containing crosslinking agent (c2). The hydroxyl group-containing polymer (b1) is a (meth)acrylic polymer having a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. The hydroxyl group-containing crosslinking agent (c2) has a hydroxyl value of 0.01 mg KOH / g or more and 100 mg KOH / g or less. Polymer (b) is a (meth)acrylic polymer. Piezoelectric materials.

11. The piezoelectric material according to claim 10, wherein the amount of fluorine polymer (a) is 60 to 99% by mass and the amount of crosslinked polymer (d) is 1 to 40% by mass, based on the total amount of fluorine polymer (a) and crosslinked polymer (d).

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