Conductive elastomer-forming composition, conductive elastomer, and polymer

Abstract

A composition for forming an electroconductive elastomer, the composition containing a (meth)acrylic polymer (a) including a unit A having at least one carboxyl group and hydroxyl group, a metal chelate compound (b), an electroconductive material (c), and a chelating agent (d).

Description

[Technical Field]

[0001] The present invention relates to a conductive elastomer that can be used as a (meth)acrylic conductive material, a conductive elastomer-forming composition for forming the conductive elastomer, and a polymer used in the conductive elastomer. More specifically, the present invention relates to a conductive film that can be suitably used in, for example, sensors, wiring, electrodes, substrates, power generation elements, speakers, microphones, noise cancellers, transducers, artificial muscles, small pumps, medical instruments, and the like used in actuators and industrial robots, and to a conductive elastomer-forming composition, conductive elastomer, and polymer that can be suitably used as raw materials for the conductive film. [Background technology]

[0002] As conductive materials, there have been proposed a carbon nanotube rubber composition consisting of carbon nanotubes, rubber, and an ionic liquid (see, for example, Patent Document 1), and a flexible conductive material having a matrix and a conductive material dispersed in the matrix, in which the matrix is formed by crosslinking a first polymer that has the function of dispersing the conductive material and a second polymer that can crosslink with the first polymer (see, for example, Patent Document 2).

[0003] Furthermore, in recent years, there has been an increasing demand for conductive films that are suitable for use in sensors, wiring, electrodes, substrates, power generation elements, speakers, microphones, noise cancellers, transducers, artificial muscles, small pumps, medical instruments, etc., used in actuators, industrial robots, etc., and that have excellent flexibility and elongation over a wide range of the rate of change of electrical resistance. For example, a (meth)acrylic conductive material that includes a (meth)acrylic elastomer containing a (meth)acrylic monomer having a specific structure and a conductive material has been proposed as a conductive film that has excellent flexibility and elongation over a wide range of the rate of change of electrical resistance (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2009 / 102077 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-35974 [Patent Document 3] International Publication No. WO2018 / 055890 Summary of the Invention [Problem to be solved by the invention]

[0005] When a conductive elastomer is used as a conductive material in an actuator, etc., the conductive elastomer may repeatedly expand and contract due to displacement caused by application of voltage. However, repeated expansion and contraction of the conductive elastomer can increase the resistance value of the conductive elastomer and decrease its conductivity. Because such a decrease in conductivity affects the performance maintenance and life cycle of the product, there is a strong demand for the development of a conductive elastomer that is less affected by repeated expansion and contraction.

[0006] In order to solve the above-mentioned problems, an object of the present invention is to provide a conductive elastomer-forming composition capable of forming a conductive elastomer in which a decrease in conductivity due to repeated stretching is suppressed, a conductive elastomer using the same, and a polymer used in the elastomer. [Means for solving the problem]

[0007] <1> a (meth)acrylic polymer (a) containing units A having at least one of a carboxyl group and a hydroxyl group; a metal chelate compound (b); A conductive material (c); a chelating agent (d); A conductive elastomer-forming composition comprising: <2> The unit A is a unit derived from a (meth)acrylic monomer represented by the following formula (I): <1> The conductive elastomer-forming composition according to claim 1. [ka] (In the formula, R 1 represents a hydrogen atom or a methyl group, X represents a carboxyl group or a hydroxyl group, Z represents an alkyl group having 1 to 10 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms, and the alkyl group and the alkoxyalkyl group may contain an ester bond. n represents 0 or 1. <3> containing a solvent, <1> or <2> The conductive elastomer-forming composition according to claim 1. <4> The (meth)acrylic polymer (a) has a unit B derived from a (meth)acrylic monomer represented by the following formula (II): <1> ~ <3> 10. The conductive elastomer-forming composition according to claim 9, wherein the conductive elastomer-forming composition is a conductive elastomer-forming composition according to any one of claims 1 to 9. [ka] (In the formula, R 1 is a hydrogen atom or a methyl group, R 2 represents an alkyl group having 1 to 18 carbon atoms or an alkoxyalkyl group having 2 to 18 carbon atoms, which may have a halogen atom. <5> The aforementioned <1> ~ <4> 10. A conductive elastomer formed using the conductive elastomer-forming composition according to any one of the preceding items. <6> A conductive elastomer comprising: a (meth)acrylic polymer (a) having a unit A having at least one of a carboxyl group and a hydroxyl group; and a conductive material (c), wherein the (meth)acrylic polymer (a) has crosslinked sites formed by crosslinking via metal atoms. <7> The metal atom is at least one selected from Al and Ti. <6> The conductive elastomer according to claim 1. <8> The Young's modulus is 30 MPa or less. <6> or <7> The conductive elastomer according to claim 1. <9> A1 unit derived from acrylic acid; and units B1 derived from isostearyl acrylate, the units A1 are crosslinked via at least one selected from Al and Ti, the content of the unit A1 is 0.1 to 10 mol %, The content ratio of the unit B1 is 90 to 99.9 mol %. Polymer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a conductive elastomer-forming composition capable of forming a conductive elastomer in which a decrease in conductivity due to repeated stretching is suppressed, a conductive elastomer using the same, and a polymer used in the elastomer. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic plan view showing an embodiment of an actuator. [Figure 2] 2 is a schematic cross-sectional view of the actuator taken along line AA in FIG. 1. FIG. [Figure 3] FIG. 10 is a schematic diagram for explaining the displacement of an elastomer. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described below, but the contents of the present invention are not limited to the following description. Furthermore, throughout this specification, "alkyl (meth)acrylate" means "alkyl acrylate" or "alkyl methacrylate," "hydroxyalkyl (meth)acrylate" means "hydroxyalkyl acrylate" or "hydroxyalkyl methacrylate," and "(meth)acryloyl" means "acryloyl" or "methacryloyl." Furthermore, unless otherwise specified, when referring to an "alkyl group," it includes alkyl groups with linear, branched, and alicyclic structures. Furthermore, when a numerical range is indicated using "~," it is intended to include both ends of the range.

[0011] <<Conductive elastomer-forming composition>> The conductive elastomer-forming composition of the present embodiment (hereinafter may be simply referred to as "the composition of the present embodiment") contains a (meth)acrylic polymer (a) (hereinafter may be simply referred to as "the (meth)acrylic polymer (a)") containing a unit A having at least one of a carboxyl group and a hydroxyl group, a metal chelate compound (b), a conductive material (c), and a chelating agent (d).

[0012] The conductive elastomer-forming composition contains a (meth)acrylic polymer (a), a metal chelate compound (b), a conductive material (c), and a chelating agent (d). By applying energy such as heat to the composition, the (meth)acrylic polymer (a) can be crosslinked by the metal chelate compound (b). This crosslinking reaction forms the conductive elastomer of the present embodiment, in which the (meth)acrylic polymer (a) having crosslinking sites crosslinked via the chelate metal of the metal chelate compound (b) forms a polymer matrix, and the conductive material (c) is dispersed within the (meth)acrylic polymer (a). Hereinafter, the (meth)acrylic polymer (a) having crosslinking sites crosslinked via the chelate metal of the metal chelate compound (b) may be referred to as "polymer X" as appropriate. In this embodiment, the term "crosslinking" does not necessarily mean that the (meth)acrylic polymer (a) and the chelate metal are bonded together by a covalent bond, but also includes a form in which the (meth)acrylic polymer (a) and the chelate metal are bonded together by a bond other than a covalent bond, such as a coordinate bond.

[0013] Here, the "conductive elastomer" of this embodiment refers to an elastic material that includes a (meth)acrylic polymer (a) containing a unit A having at least one of a carboxyl group and a hydroxyl group, and an electrically conductive material (c), and the (meth)acrylic polymer (a) has crosslinked sites crosslinked via metal atoms. In other words, the electrically conductive elastomer of this embodiment includes a polymer X and an electrically conductive material (c), and the polymer X constitutes a "polymer matrix" in the electrically conductive elastomer, and the electrically conductive material (c) dispersed in the polymer matrix is an elastic composite material.

[0014] On the other hand, the reason why the conductivity of conventional conductive elastomers (stretchable materials) containing a polymer cross-linked with isocyanate or the like and a conductive material decreases after repeated stretching is unclear. However, for example, because the cross-linked structure by isocyanate is formed by a covalent bond, once the bond breaks due to the stretching of the conductive elastomer, it does not reform and the cross-linked structure of the polymer irreversibly collapses. As the cross-linked structure of the polymer collapses, the density of the polymer (polymer matrix) in the conductive elastomer tends to decrease (volume expands), and this decrease in density causes a deviation in the distance between the conductive materials in the matrix. When a deviation in the distance between the conductive materials in the matrix occurs, the resistance value increases in areas where the distance between the conductive materials is greater. For this reason, it is presumed that the conductivity of conventional conductive elastomers decreases as a result of repeated stretching. In contrast, in the conductive elastomer of this embodiment, the (meth)acrylic polymer (a) is cross-linked mainly by coordinate bonds of a chelate metal, so even if a bond breaks, it can reform. Therefore, even in regions where bonds have been broken due to the expansion and contraction of the conductive elastomer, there is a high possibility that crosslinked structures will be reformed, and the durability of the polymer matrix (polymer X) itself (durability of the crosslinked structure) against expansion and contraction is high. Furthermore, in the conductive elastomer of this embodiment, the chelate metal contained in the crosslinked regions of polymer X acts as a conductive additive. For these various reasons, even if the density of the polymer matrix (polymer) decreases, the effect of the conductive additive is less affected by deviations in the distance between the conductive materials therein, and it is presumed that this makes it possible to suppress a decrease in conductivity due to the expansion and contraction of the conductive elastomer.

[0015] <(Meth)acrylic polymer (a) having units A having at least one of a carboxyl group and a hydroxyl group> The (meth)acrylic polymer (a) is a polymer containing units A having at least one of a carboxyl group and a hydroxyl group. The (meth)acrylic polymer (a) may contain other units in addition to the units A.

[0016] (Unit A having at least one of a carboxyl group and a hydroxyl group) The unit A is preferably a unit derived from a (meth)acrylic monomer having at least one of a carboxyl group and a hydroxyl group, and the carboxyl group or the hydroxyl group in the unit A constitutes a crosslinking site with the chelate metal in the crosslinking reaction between the (meth)acrylic polymer (a) and the metal chelate compound (b).

[0017] The number of carboxyl groups and hydroxyl groups in the unit A is not particularly limited, but is preferably about 1 to 3, and more preferably 1. Furthermore, the unit A may contain either or both of a carboxyl group and a hydroxyl group, but preferably contains only one of them.

[0018] From the viewpoint of durability of the resulting conductive elastomer, the unit A is preferably a unit derived from a (meth)acrylic monomer represented by the following formula (I).

[0019] [ka] (In the formula, R 1 represents a hydrogen atom or a methyl group, X represents a carboxyl group or a hydroxyl group, Z represents an alkyl group having 1 to 10 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms, and the alkyl group and the alkoxyalkyl group may contain an ester bond. n represents 0 or 1.

[0020] In formula (I), R 1 is a hydrogen atom or a methyl group. 1 In this case, hydrogen atoms are preferred from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0021] In formula (I), X is a carboxyl group or a hydroxyl group. X is not particularly limited, but is preferably a carboxyl group from the viewpoint of reactivity with the metal chelate compound (b).

[0022] In formula (I), Z is a divalent linking group selected from an alkyl group having 1 to 10 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms. In formula (I), the alkyl group and the alkoxyalkyl group may have other substituents such as a halogen atom, and may particularly contain an ester bond (-OC(=O)-). There is no particular superiority or inferiority between an alkyl group and an alkoxy group for Z, but an alkyl group is preferred from the viewpoint of suppressing moisture-induced deterioration of the resulting conductive elastomer, such as rust generation and deterioration due to hydrolysis of the polymer X.

[0023] In Z, the alkyl group has 1 to 10 carbon atoms, and from the viewpoint of the mechanical properties (elongation, durability, etc.) of the resulting conductive elastomer, preferably 1 to 5. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, an n-pentyl group, an isoamyl group, an n-hexyl group, an isohexyl group, a cyclohexyl group, and an n-octyl group, but the present invention is not limited to these examples.

[0024] In Z, the alkoxyalkyl group has 2 to 12 carbon atoms, and from the viewpoint of the mechanical properties of the resulting conductive elastomer, preferably 2 to 5. Examples of the alkoxyalkyl group include alkoxy groups having 2 to 6 carbon atoms, such as a methoxyethyl group, an ethoxyethyl group, and a methoxybutyl group, and an alkoxyalkyl group having an alkyl group having 2 to 6 carbon atoms, but the present invention is not limited to these examples.

[0025] The alkyl group represented by Z may contain a hydroxyl group or a carboxyl group as another substituent. However, it is preferable that the number of hydroxyl groups and carboxyl groups in Z is appropriately adjusted within a range that does not impede the object of this embodiment in terms of the number of hydroxyl groups and carboxyl groups in the entire unit A. Furthermore, examples of halogen atoms that can be mentioned as other substituents include those described below for formula (II). Furthermore, examples of (meth)acrylic monomers represented by formula (I) containing an ester bond (-OC(=O)-) as Z include, for example, HOA-MS described below.

[0026] The (meth)acrylic monomer represented by formula (I) is not particularly limited, and examples thereof include acrylic acid (AA), hydroxyethyl (meth)acrylate, 4-hydroxybutyl acrylate (4HBA), hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and 2-acryloyloxyethyl succinic acid (HOA-MS). Among these examples, from the viewpoint of obtaining a conductive elastomer with low volume resistivity, preferred examples of the unit A include units derived from acrylic acid (AA), 4-hydroxybutyl acrylate (4HBA), or 2-acryloyloxyethyl succinic acid (HOA-MS) shown below.

[0027] [ka]

[0028] Other examples of the unit A other than the unit derived from the (meth)acrylic monomer represented by formula (I) include units derived from carboxyl group-containing monomers such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and crotonic acid.

[0029] (other monomer component units) The (meth)acrylic polymer (a) can be composed of only the unit A, but may also contain, if necessary, other monomer component units that do not have a carboxyl group or a hydroxyl group in addition to the unit A, provided that the object of this embodiment is not impaired. As the other monomer component units, units derived from a monomer copolymerizable with the unit A (hereinafter referred to as a "copolymerizable monomer") can be used.

[0030] -Unit B- The (meth)acrylic polymer (a) may contain, as a copolymerizable monomer, a unit B which is a unit other than the unit A and is derived from a (meth)acrylic monomer copolymerizable with the unit A. Although not particularly limited, from the viewpoint of the flexibility and extensibility of the resulting conductive elastomer, the (meth)acrylic polymer (a) may have, as the unit B, a unit derived from a (meth)acrylic monomer represented by the following formula (II): [ka] (In the formula, R 1 is a hydrogen atom or a methyl group, R 2 represents an alkyl group having 1 to 18 carbon atoms or an alkoxyalkyl group having 2 to 18 carbon atoms, which may have a halogen atom.

[0031] In formula (II), R 1 is a hydrogen atom or a methyl group. 1 Among these, hydrogen atoms are preferred from the viewpoint of obtaining a conductive film that is excellent in workability and formability, as well as excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0032] In the (meth)acrylic monomer represented by formula (II), R 2 is an alkyl group having 1 to 18 carbon atoms or an alkoxyalkyl group having 2 to 18 carbon atoms, which may have a halogen atom.

[0033] Examples of the alkyl group having 1 to 18 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, an n-pentyl group, an isoamyl group, an n-hexyl group, an isohexyl group, a cyclohexyl group, an n-octyl group, and an i-octadecyl group, but the present embodiment is not limited to these examples.

[0034] Examples of the alkoxyalkyl group having 2 to 18 carbon atoms include an alkoxy group having 1 to 9 carbon atoms, such as a methoxyethyl group, an ethoxyethyl group, and a methoxybutyl group, and an alkoxyalkyl group having an alkyl group having 1 to 9 carbon atoms, but the present embodiment is not limited to these examples.

[0035] As mentioned above, in formula (II), R 2 The alkyl group or alkoxyalkyl group represented by the formula (I) may have another substituent such as a halogen atom. Examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these halogen atoms, a fluorine atom is preferred from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance. The number of halogen atoms contained in the alkyl group varies depending on the number of carbon atoms in the alkyl group, and therefore cannot be determined in general. Therefore, it is preferable to appropriately adjust the number within a range that does not impede the object of this embodiment.

[0036] Examples of the alkyl group having 1 to 10 carbon atoms and a halogen atom include a trifluoromethyl group, a trifluoroethyl group, a trifluoropropyl group, and a trifluorobutyl group, but the present embodiment is not limited to these examples.

[0037] Among the (meth)acrylic monomers represented by formula (II), from the viewpoint of obtaining a conductive elastomer having excellent workability and moldability, as well as excellent flexibility and elongation over a wide range of the rate of change of electrical resistance, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-pentyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, methylpentyl (meth)acrylate, n-octyl (meth)acrylate, nonanol (meth)acrylate, cyclohexyl (meth)acrylate, isostearyl (meth)acrylate, and the like, in which R 1 is a hydrogen atom or a methyl group, and R 2 is an alkyl group having 1 to 18 carbon atoms; (meth)acrylic monomers such as 2,2,2-trifluoroethyl acrylate, in which R 1 is a hydrogen atom or a methyl group, and R 2 (meth)acrylic monomers such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, and phenoxyethyl acrylate, in which R 1 is a hydrogen atom or a methyl group, and R 2 is a (meth)acrylic monomer in which the alkyl group is an alkoxyalkyl group having 2 to 12 carbon atoms. Among these examples, preferred examples of unit B include units derived from ethyl (meth)acrylate (hereinafter referred to as ethyl acrylate), isostearyl (meth)acrylate, or 2,2,2-trifluoroethyl acrylate shown below.

[0038] [ka]

[0039] (other monomer component units) The (meth)acrylic polymer (a) can be composed of only the unit A, or the unit A and the unit B. However, if necessary, in addition to the unit A and the unit B, other monomer component units may be contained within the scope that does not impair the object of this embodiment. As the other monomer component units, units derived from a monomer copolymerizable with the unit A or the unit B (hereinafter referred to as a "copolymerizable monomer") can be used. When the (meth)acrylic polymer (a) contains the unit B derived from the (meth)acrylic monomer represented by formula (II) as the unit B, only the unit derived from the (meth)acrylic monomer represented by formula (II) is treated as the unit B, and the monomer component units other than the unit A and the unit B are treated as the other monomer component units.

[0040] -Other monomer component units- Examples of other monomer component units include amide group-containing monomers, aryl group-containing monomers, styrene-based monomers, nitrogen atom-containing monomers, fatty acid vinyl ester-based monomers, betaine monomers, glycidyl group-containing monomers, silicone group-containing monomers, and cycloalkyl group-containing monomers, but the present embodiment is not limited to these examples.

[0041] Examples of amide group-containing monomers 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, but the present embodiment is not limited to these examples. These monomers may be used alone or in combination of two or more.

[0042] Examples of aryl group-containing monomers include aryl (meth)acrylates in which the aryl group has 6 to 12 carbon atoms, such as benzyl (meth)acrylate, but the present embodiment is not limited to these examples. Examples of aryl groups include phenyl group (C6H5-), tolyl group (CH3C6H4-), xylyl group ((CH3)2C6H3-), naphthyl group (C 10 H8-) and others.

[0043] Examples of styrene-based monomers include styrene and α-methylstyrene, but the present embodiment is not limited to these examples.

[0044] Examples of nitrogen atom-containing monomers include N-vinylpyrrolidone and N-vinylcaprolactam, but the present embodiment is not limited to these examples.

[0045] Examples of fatty acid vinyl ester monomers include vinyl acetate and vinyl propionate, but the present embodiment is not limited to these examples.

[0046] Examples of betaine monomers include N-acryloyloxymethyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-methacryloyloxymethyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-acryloyloxymethyl-N,N-dimethylammonium ethyl-α-sulfobetaine, N-methacryloyloxymethyl-N,N-dimethylammonium ethyl-α-sulfobetaine, N-acryloyloxymethyl-N,N-dimethylammonium propyl-α-sulfobetaine, and N-methacryloyloxymethyl-N,N-dimethylammonium propyl-α-sulfobetaine. Acryloyloxymethyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-acryloyloxymethyl-N,N-dimethylammonium butyl-α-sulfobetaine, N-methacryloyloxymethyl-N,N-dimethylammonium butyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammonium Monomethanolethyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammoniumethyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammoniumpropyl-α-sulfobetaine, N-acryloyloxyethyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, N-methacryloyloxyethyl-N,N-dimethylammoniumbutyl-α-sulfobetaine, N -Acryloyloxypropyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-Methacryloyloxypropyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-Acryloyloxypropyl-N,N-dimethylammonium ethyl-α-sulfobetaine, N-Methacryloyloxypropyl-N,N-dimethylammonium ethyl-α-sulfobetaine, N-Acryloyloxypropyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-Methacryloyloxypropyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-acryloyloxypropyl-N,N-dimethylammonium butyl-α-sulfobetaine, N-methacryloyloxypropyl-N,N-dimethylammonium butyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-methacryloyloxybutyl-N,N-dimethylammonium methyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammonium ethyl-α-sulfobetaine, N-methacryloyloxybutyl-N,N-dimethylammonium ethyl-α-sulfobetaine Examples of sulfobetaine monomers include N-(meth)acryloyloxyalkyl-N,N-dimethylammonium alkyl-α-sulfobetaines such as sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-methacryloyloxybutyl-N,N-dimethylammonium propyl-α-sulfobetaine, N-acryloyloxybutyl-N,N-dimethylammonium butyl-α-sulfobetaine, and N-methacryloyloxybutyl-N,N-dimethylammonium butyl-α-sulfobetaine, but the present embodiment is not limited to these examples. These sulfobetaine monomers may be used alone or in combination of two or more.

[0047] Glycidyl group-containing monomers include glycidyl (meth)acrylate, glycidyl-[-O-(CH2) n -] m -(meth)acrylate (where n is an integer of 1 to 4, and m is an integer of 1 to 20), but the present embodiment is not limited to these examples.

[0048] Silicone group-containing monomers are (Rc)-[-O-Si(Ra)(Rb)] xExamples of the monomer containing a - group include silicone esters of (meth)acrylic acid, but the present embodiment is not limited to these examples. Here, Ra, Rb, and Rc can be selected from any chemically possible group (e.g., alkyl group, alkoxy group, cycloalkyl group, cycloalkyloxy group, aryl group, aryloxy group, etc.), and x is an integer, for example, 1, 2, 3, or 4. Examples of the silicone group include polydimethylsiloxyl group and trialkoxysilyl group (e.g., trimethoxysilyl group, triethoxysilyl group), but the present embodiment is not limited to these examples.

[0049] The cycloalkyl group-containing monomer is a monomer containing a cycloalkyl group, and examples thereof include C3-12 cycloalkyl (meth)acrylates, but the present embodiment is not limited to these examples. In this specification, the term "cycloalkyl group" refers to a monocyclic or polycyclic saturated hydrocarbon group, and includes those with a crosslinked structure. For example, a "C3-12 cycloalkyl group" refers to a cyclic alkyl group having 3 to 12 carbon atoms. Specific examples of the "C3-12 cycloalkyl group" include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, and isobornyl groups, but the present embodiment is not limited to these examples. These monomers may be used alone or in combination of two or more.

[0050] (Synthesis of (meth)acrylic polymer (a)) The (meth)acrylic polymer (a) in this embodiment can be obtained by polymerizing each monomer component that becomes the unit A, etc. The method for synthesizing each monomer component is not particularly limited, and known methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used. In this embodiment, it is preferable to employ bulk polymerization from the viewpoint of achieving a high molecular weight of the (meth)acrylic polymer (a).

[0051] The content of the unit A in the (meth)acrylic polymer (a) is preferably 0.1 to 10 mol %, more preferably 0.25 to 5 mol %, even more preferably 0.5 to 3 mol %, and particularly preferably 0.5 to 1.5 mol %, from the viewpoint of obtaining a polymer X having excellent flexibility and elongation after a crosslinking reaction with the metal chelate compound (b). When the unit B is used, the content of the unit B in the (meth)acrylic polymer (a) is not particularly limited, but from the viewpoint of obtaining a polymer X having excellent flexibility and elongation, it is preferably 90 to 99.9 mol %, more preferably 97 to 99.5 mol %, and particularly preferably 98.5 to 99.5 mol %. The (meth)acrylic polymer (a) may contain one or more types of units A. That is, the (meth)acrylic polymer (a) may contain one or more types of units A, or may contain one or more types of units B.

[0052] Examples of the combination of monomers constituting the (meth)acrylic polymer (a) are not particularly limited, but include a combination of units derived from at least one selected from acrylic acid (AA), 4-hydroxybutyl acrylate (4HBA), and 2-acryloyloxyethyl succinic acid (HOA-MS) as unit A, and units derived from at least one selected from ethyl acrylate (EA), isostearyl (meth)acrylate (ISTA), and 2,2,2-trifluoroethyl acrylate (V#3F) as unit B. Specific examples include the following combinations:

[0053] (1) EA / AA (2) EA / V#3F / AA (3) ISTA / EA / AA (4) ISTA / V#3F / AA (5) ISTA / V#3F / 4HBA (6) ISTA / EA / HOA-MS (7) ISTA / V#3F / HOA-MS (8) EA / 4HBA

[0054] The (meth)acrylic polymer (a) can be synthesized by polymerizing a monomer component by irradiating it with ultraviolet light of a specific irradiance. Such ultraviolet light irradiation can be arbitrarily set and carried out by a person skilled in the art. When the (meth)acrylic polymer (a) is obtained by bulk polymerizing the monomer component using ultraviolet light, a complicated drying operation for removing the solvent is not required, and the process is excellent in workability.

[0055] Here, ultraviolet light refers to electromagnetic waves with wavelengths shorter than visible light and longer than X-rays. The upper limit of the short wavelength end of visible light is 400 nm, and ultraviolet light can be defined as electromagnetic waves with wavelengths shorter than this. The lower limit of the wavelength of ultraviolet light is about 10 nm, and any electromagnetic wave with a wavelength longer than this is understood to fall into the category of ultraviolet light. The wavelength of the ultraviolet light used in this embodiment may be any wavelength, and an appropriate wavelength can be selected depending on the purpose. For example, in this embodiment, any wavelength may be used as long as it can produce an initial effect on the monomer. Typically, it is a wavelength that can be irradiated by the light source used in the examples. Specifically, a light source with a wavelength of about 150 nm to 400 nm is used, and preferably 300 nm to 400 nm.

[0056] The preferred irradiance of the ultraviolet light used in this embodiment varies depending on the starting material. The ultraviolet light irradiation device is not particularly limited, and examples thereof include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a black light lamp, a UV electrodeless lamp, a short arc lamp, and an LED.

[0057] A polymerization initiator can be used when polymerizing the monomer components. Examples of the polymerization initiator include a photopolymerization initiator and a thermal polymerization initiator. Among these polymerization initiators, a photopolymerization initiator is preferred from the viewpoint of preventing thermal history from remaining in the (meth)acrylic polymer (a).

[0058] Examples of the photopolymerization initiator 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, 4,4'-ditert-butyldiphenylphosphine oxide ... 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-diphenylethan-1-one, phenylglycine Photoradical polymerization initiators such as oxylic 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-pyrrol-1-yl)phenyltitanium], 2,4,6-tris(trichloromethyl)-1,3 Examples of photocationic ring-opening polymerization initiators include, but are not limited to, 2,4-bis(trichloromethyl)-6-(p-methoxyphenylvinyl)-1,3,5-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 embodiment is not limited to these examples.These photopolymerization initiators may be used alone or in combination of two or more.

[0059] Examples of the thermal polymerization initiator include azo-based polymerization initiators such as dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), dimethyl 2,2'-azobisisobutyrate, and azobisdimethylvaleronitrile, and peroxide-based polymerization initiators such as benzoyl peroxide, potassium persulfate, and ammonium persulfate, but the present embodiment is not limited to these examples. These polymerization initiators may be used alone or in combination of two or more.

[0060] The amount of the polymerization initiator cannot be determined in general because it differs depending on the type of the polymerization initiator, but it is usually preferably about 0.01 to 20 parts by mass per 100 parts by mass of the monomer component.

[0061] When polymerizing the monomer components, a chain transfer agent can be used to adjust the molecular weight of the resulting (meth)acrylic polymer (a). Examples of chain transfer agents include compounds having a thiol group, such as lauryl mercaptan, dodecyl mercaptan, and thioglycerol; and inorganic salts, such as sodium hypophosphite and sodium hydrogen sulfite; but the present embodiment is not limited to these examples. These chain transfer agents may be used alone 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, but is generally preferably about 0.01 to 10 parts by mass per 100 parts by mass of the monomer components.

[0062] The atmosphere in which the monomer components are polymerized is not particularly limited, and may be air or an inert gas such as nitrogen gas or argon gas.

[0063] The temperature at which the monomer components are polymerized is not particularly limited, and is usually preferably about 5 to 100° C. The time required to polymerize the monomer components varies depending on the polymerization conditions and cannot be generally determined, so is arbitrary, but is usually about 0.5 to 20 hours.

[0064] The polymerization reaction can be terminated at any time when the amount of the remaining monomer component is 20% by mass or less. The amount of the remaining monomer component can be measured, for example, by gel permeation chromatography (GPC).

[0065] The weight-average molecular weight of the (meth)acrylic polymer (a) is preferably 200,000 to 10,000,000, more preferably 300,000 to 3,000,000, and particularly preferably 400,000 to 2,500,000, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance. In this embodiment, the weight-average molecular weight of the (meth)acrylic polymer (a) can be measured in polystyrene equivalent terms using, for example, gel permeation chromatography (Tosoh Corporation, product number: HLC-8320GPC, column: Tosoh Corporation, product number: TSKgel GMHH-R, solvent: tetrahydrofuran, flow rate: 0.6 mL / min).

[0066] From the viewpoint of obtaining a conductive film that is excellent in workability and moldability as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance, the number-average molecular weight of the (meth)acrylic polymer (a) is preferably 100,000 to 5,000,000, more preferably 150,000 to 1,500,000, and even more preferably 200,000 to 1,000,000. The number-average molecular weight of the (meth)acrylic polymer (a) can be measured, for example, in terms of polystyrene, using gel permeation chromatography (Tosoh Corporation, product number: HLC-8320GPC, column: Tosoh Corporation, product number: TSKgel GMHH-R, solvent: tetrahydrofuran, flow rate: 0.6 mL / min).

[0067] The molecular weight distribution (weight average molecular weight / number average molecular weight, hereinafter the same) of the (meth)acrylic polymer (a) is 1 or more, 1.5 or more, preferably 2 or more, 2.5 or more, more preferably 3 or more, 3.5 or more, from the viewpoint of obtaining a conductive film that is excellent in workability and moldability and that is also excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance. Also, from the viewpoint of obtaining a conductive film that is excellent in workability and moldability and that is also excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance, the molecular weight distribution is 6 or less, 5.5 or less, 5 or less, preferably 4.5 or less, more preferably 4 or less.

[0068] The content of the (meth)acrylic polymer (a) in the composition of this embodiment is preferably 5 to 95 mass %, more preferably 7.5 to 50 mass %, and particularly preferably 9 to 15 mass %, based on the total amount of the composition of this embodiment, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance. In the composition of this embodiment, the (meth)acrylic polymer (a) may be used alone or in combination of two or more kinds.

[0069] <Metal chelate compounds (b)> The composition of the present embodiment contains a metal chelate compound (b). In the present embodiment, by applying energy such as heat or light to the composition of the present embodiment, the (meth)acrylic polymer (a) can be crosslinked by the metal chelate compound (b).

[0070] A metal chelate compound is composed of a chelating agent portion made of a chelating agent such as ethyl acetoacetate and a chelate metal made of metal atoms, and has a structure in which the chelating agent portion is coordinated to protect the chelate metal.

[0071] When energy such as heat is applied to the composition of this embodiment, the chelating agent portion of the metal chelate compound (b) volatilizes, and a crosslinking reaction between the (meth)acrylic polymer (a) and the chelate metal proceeds. This crosslinking reaction proceeds when the chelating agent portion of the metal chelate compound (b) volatilizes due to heat or the like, rupturing the coordinate bond between the chelate metal and the chelating agent portion. When the chelating agent portion volatilizes and the coordinate bond is ruptured, the hydroxyl group or carboxyl group of unit A of the (meth)acrylic polymer (a) coordinates with the chelate metal, and a crosslinking reaction between the (meth)acrylic polymer (a) and the chelate metal proceeds. Therefore, by applying energy such as heat to a mixture of the (meth)acrylic polymer (a) and the metal chelate compound (b), a (meth)acrylic polymer (a) having a site crosslinked by the chelate metal (i.e., polymer X) can be obtained.

[0072] In the metal chelate compound, the central metal (chelate metal) is preferably a metal or semiconductor atom from periods 3 to 5 of the periodic table, more preferably period 3 metals such as Al and Si, period 4 metals such as Ti, Mn, Fe, Co, Ni, Cu, Zn, and Ge, and period 5 metals such as In and Sn, and particularly preferably Al and Ti.

[0073] The metal chelate compound (b) is not particularly limited, and known metal chelate compounds can be appropriately selected and used. Examples of the metal chelate compound (b) include aluminum chelate compounds such as aluminum tris(acetylacetonate), aluminum alkylacetoacetate diisopropylate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisacetylacetate, aluminum tris(alkylacetoacetate), and aluminum acetylacetate diisopropylate; Titanium chelate compounds such as titanium acetylacetonate, titanium tetraacetylacetate, polytitanium acetylacetonate, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate, titanium triethanolamine, dihydroxy bis(lactiacido)titanate, dihydroxy bis(lactato)titanium monoammonium salt, dihydroxy bis(lactato)titanium diammonium salt, propanedioxytitanium bis(ethylacetoacetate), diisopropoxy bis(acetylacetone)titanate, dibutoxy bis(triethanolamine)titanate, tetraoctylene glycol titanate, and diisopropoxytitanium bis(ethylacetoacetate); Zirconium chelate compounds such as zirconium acetate, zirconium acetylacetate, zirconium butoxyacetylacetonate, zirconium bisacetylacetonate, zirconium ethylacetoacetate, and zirconium acetylacetonate-ethylacetoacetate; Examples include zinc acetylacetate, nickel acetylacetate, and iron acetylacetate. Suitable examples of the metal chelate compound in this embodiment include aluminum-based metal chelate compounds and titanium-based chelate compounds using Al or Ti as the metal atom. Examples of the aluminum-based metal chelate compounds include the following:

[0074] [ka]

[0075] The content of the metal chelate compound (b) in the composition of this embodiment is preferably 10 to 5,000 parts by mass, more preferably 50 to 1,000 parts by mass, and particularly preferably 100 to 2,000 parts by mass per 100 parts by mass of the total amount of units A in the (meth)acrylic polymer (a), from the viewpoint of obtaining a conductive elastomer that exhibits excellent flexibility and elongation over a wide range of the rate of change of electrical resistance and that exhibits suppressed decrease in conductivity after stretching. In the composition of this embodiment, the metal chelate compound (b) may be used alone or in combination with two or more types. From the same viewpoint, the content of the metal chelate compound (b) in the composition of this embodiment is preferably 0.1 to 1.0% by mass, more preferably 0.2 to 0.9% by mass, and particularly preferably 0.25 to 0.8% by mass, relative to the total amount of the composition of this embodiment.

[0076] <Conductive material (c)> The composition of this embodiment contains a conductive material (c). By containing the conductive material (c) together with the (meth)acrylic polymer (a) and the metal chelate compound (b), the composition of this embodiment can obtain a conductive elastomer in which the conductive material (c) is dispersed in a polymer matrix of the (meth)acrylic polymer (a) (polymer X) having sites crosslinked by the chelate metal.

[0077] Examples of the conductive material (c) include natural graphite such as flake graphite, graphite such as artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, carbon-based materials such as graphene, carbon nanotubes, and fullerenes; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; powders of metal particles such as copper, nickel, aluminum, silver, and silver-coated copper; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and organic conductive materials such as polyphenylene derivatives. However, the conductive material (c) is not limited to these examples. Each of the conductive materials (c) may be used alone, or two or more types may be used in combination. Among these conductive materials, carbon nanotubes, carbon black, graphene, and metal particles are preferred from the viewpoint of obtaining a conductive film that is excellent in workability and formability, as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance, and carbon nanotubes, carbon black, graphene, and silver particles are more preferred, and silver particles or carbon nanotubes are even more preferred from the viewpoint of obtaining a conductive elastomer in which the decrease in conductivity after stretching is suppressed.

[0078] The content of the solid content of the conductive material (c) in the total solid content of the (meth)acrylic polymer (a) and the conductive material is preferably 3 to 95 mass%, more preferably 5 to 90 mass%, and particularly preferably 7 to 85 mass%, from the viewpoint of achieving high conductivity and providing excellent workability and moldability, as well as obtaining a conductive elastomer that is excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0079] In this specification, the content of the solid content of the conductive material in the total solid content of the (meth)acrylic polymer (a) and the conductive material (c) is expressed by the formula: [content (mass%) of the solid content of the conductive material (c) in the total solid content of the (meth)acrylic polymer (a) and the conductive material (c)] = [(solid content of conductive material (c)) / [solid content of (meth)acrylic polymer (a)+solid content of conductive material (c)]]×100.

[0080] -Carbon nanotubes- Examples of carbon nanotubes include single-walled carbon nanotubes, which have a hollow cylindrical structure formed by rolling a single sheet of graphite (graphene sheet) into a cylindrical shape; multi-walled carbon nanotubes, which have a structure formed by concentrically stacking multiple single-walled carbon nanotubes of different diameters; single-walled carbon nanotubes produced by the super-growth method; carbon nanocones, which are single-walled carbon nanotubes with closed conical ends; and carbon nanotubes encapsulating fullerenes. The present invention is not limited to these examples. These carbon nanotubes may be used alone or in combination of two or more types. Among these carbon nanotubes, multi-walled carbon nanotubes are preferred from the viewpoint of obtaining a conductive elastomer that exhibits a large amount of displacement when a low voltage is applied.

[0081] The length of the carbon nanotubes is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance, and is even more preferably 1 to 90 μm from the viewpoint of obtaining a conductive elastomer that has a large displacement amount at low voltage.

[0082] The diameter of the carbon nanotubes is preferably 10 to 50 nm, more preferably 10 to 20 nm, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0083] The solid content of carbon nanotubes in the total solid content of the (meth)acrylic polymer (a) and the carbon nanotubes is preferably 3 to 30 mass%, more preferably 5 to 25 mass%, and particularly preferably 7 to 20 mass%, from the viewpoint of obtaining a conductive elastomer that realizes high conductivity and is excellent in workability and moldability, as well as excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0084] -Metal particles- Examples of the shape of the metal particles include spherical, ellipsoidal, spindle-like, crushed, plate-like, columnar, scaly, flat, dendritic, and chain-like shapes, but the present invention is not limited to these examples. The shape of the metal particles is preferably determined appropriately depending on the application of the conductive elastomer, etc.

[0085] The average particle size of the metal particles is preferably 0.3 to 50 μm, more preferably 0.5 to 30 μm, and even more preferably 1 to 10 μm, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance. The average particle size of the metal particles means the average particle size determined in the same manner as for carbon black, which will be described later.

[0086] The content of the metal particles in the total solid content of the (meth)acrylic polymer (a) and the metal particles (for example, silver particles) is preferably 50 to 95 mass%, more preferably 55 to 90 mass%, and particularly preferably 60 to 85 mass%, from the viewpoint of achieving high conductivity and providing excellent workability and moldability, as well as obtaining a conductive elastomer that is excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0087] -Carbon black- Examples of the shape of carbon black include spherical, ellipsoidal, spindle-like, crushed, plate-like, and columnar shapes, but the present embodiment is not limited to these examples. The shape of carbon black is preferably determined appropriately depending on the application of the conductive elastomer.

[0088] The average particle size of carbon black is preferably 30 μm or less, more preferably 20 μm or less, even more preferably 10 μm or less, and even more preferably 5 μm or less, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, realizes high conductivity, and is excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance. The average particle size of carbon black means the average particle size of D50 measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Horiba, Ltd., product number: LA-910).

[0089] The content of the carbon black solids in the total solids of the (meth)acrylic polymer (a) and the carbon black is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability as well as flexibility and elongation over a wide range of rate of change of electrical resistance, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability as well as flexibility and elongation over a wide range of rate of change of electrical resistance.

[0090] -Graphene- From the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, realizes high conductivity, and is excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance, the average particle size of graphene is preferably 0.3 to 500 μm, more preferably 0.5 to 100 μm, even more preferably 1 to 50 μm, and still more preferably 3 to 20 μm. The average particle size of graphene means the average particle size determined in the same manner as for the carbon black.

[0091] The thickness of the graphene is preferably 0.1 to 500 nm, more preferably 0.5 to 100 nm, even more preferably 1 to 50 nm, and still more preferably 1 to 20 nm, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0092] The content of the solid content of graphene in the total solid content of the (meth)acrylic polymer (a) and graphene is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as in flexibility and elongation over a wide range of rate of change of electrical resistance, and is preferably 25% by mass or less, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability, as well as in flexibility and elongation over a wide range of rate of change of electrical resistance.

[0093] -Metal particles with low tap density- As the conductive material (c), metal particles with a low tap density can be used in order to further suppress changes in conductivity when the material stretches and contracts. Examples of metal particles with a low tap density include dendritic metal particles. Examples of dendritic metal particles include metal-coated particles (e.g., silver-coated dendritic copper particles) having a metal coating such as silver on at least the surface. It is unclear why using metal particles with a low tap density (bulky) can further suppress changes in conductivity when the material stretches and contracts. However, it is presumed that using metal particles with a low tap density (bulky) increases the volume ratio of the metal particles to the conductive elastomer, thereby increasing the number of contact points between the metal particles, thereby further suppressing changes in conductivity when the conductive elastomer stretches and contracts compared to spherical or flake-shaped particles.

[0094] From the above viewpoints, the conductive material (c) is preferably carbon nanotubes, carbon black, graphene, or metal particles, more preferably carbon nanotubes, carbon black, graphene, silver particles, or silver-coated copper particles, and even more preferably carbon nanotubes, silver flake particles, or dendritic silver-coated copper particles.

[0095] -Dispersion- The conductive material can be used as a dispersion liquid in which the conductive material is dispersed in a dispersion medium. Examples of dispersion media include isopropyl alcohol, toluene, N-methyl-2-pyrrolidone, and cyclopentanone, but the present invention is not limited to these examples. These dispersion media may be used alone or in combination of two or more. The amount of dispersion medium may be appropriately determined taking into consideration the type and amount of the conductive material, the type and amount of the (meth)acrylic polymer (a) to be mixed, and the like.

[0096] The nonvolatile content in the conductive material dispersion is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoint of obtaining a conductive elastomer that is excellent in workability and moldability as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance, and is preferably 60% by mass or less, more preferably 50% by mass or less, from the viewpoint of improving handleability.

[0097] The amount of nonvolatile content in the conductive material dispersion liquid means a value calculated based on the following formula, in which 1 g of the conductive material dispersion liquid is weighed, dried in a hot air dryer at a temperature of 130°C for 1 hour, and the obtained residue is taken as the nonvolatile content. formula: [Non-volatile content (mass%) in conductive material dispersion liquid] = ([mass of residue] ÷ [1 g of conductive material dispersion]) × 100

[0098] <Chelating agent (d)> The composition of the present embodiment includes a chelating agent (d). By including the chelating agent (d), the composition of the present embodiment can prevent gelation during the crosslinking reaction between the (meth)acrylic polymer (a) and the metal chelate compound (b).

[0099] The chelating agent (d) is not particularly limited, and known metal chelating compounds can be appropriately selected and used. For example, a compound corresponding to the "chelating agent portion" of the above-mentioned metal chelate compound (b) can be used as the chelating agent (d). Examples of the chelating agent (d) that can be used include alkyl acetoacetates such as acetylacetonate, acetyl acetate, and ethyl acetoacetate, isopropylate, octylene glycolate, lactate, and ethanolamine, and alkyl acetoacetates such as ethyl acetoacetate are preferably used.

[0100] The content of the chelating agent (d) in the composition of this embodiment is preferably 100 to 50,000 parts by mass, more preferably 500 to 10,000 parts by mass, and particularly preferably 1,000 to 5,000 parts by mass per 100 parts by mass of the metal chelate compound (b), from the viewpoint of effectively suppressing gelation during the crosslinking reaction between the (meth)acrylic polymer (a) and the metal chelate compound (b). In the composition of this embodiment, the chelating agent (d) may be used alone or in combination with two or more types. Furthermore, the chelating agent (d) may be the same type as the "chelating agent portion" of the metal chelate compound (b) contained in the composition of this embodiment, or a different chelating agent may be used.

[0101] When the (meth)acrylic polymer (a) can be dissolved in the chelating agent (d), the chelating agent (d) can be used instead of the solvent described below.

[0102] <Other ingredients> (solvent) The composition of the present embodiment can be easily produced, for example, by dissolving the (meth)acrylic polymer (a) in a solvent and mixing the resulting resin solution with the metal chelate compound (b), the conductive material (c), the chelating agent (d), and, if necessary, additives, etc. The order in which these components are mixed is arbitrary, and, for example, these components may be mixed all at once.

[0103] Examples of solvents for dissolving the (meth)acrylic polymer (a) include aromatic solvents such as toluene, xylene, and trimethylbenzene; alcoholic solvents such as isopropyl alcohol, n-butyl alcohol, and methoxymethylbutanol; ether solvents such as propylene glycol methyl ether, dipropylene glycol methyl ether, ethyl cellosolve, and butyl cellosolve; ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monobutyl acetate, and butoxyacetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diacetone alcohol; organic solvents such as amide solvents such as dimethylformamide; and hydrocarbon solvents such as isododecane. However, this embodiment is not limited to these examples. Furthermore, as described above, if the (meth)acrylic polymer (a) can be dissolved in the chelating agent (d), the chelating agent (d) can be used as a solvent. These solvents may be used alone or in combination of two or more. The amount of the solvent is not particularly limited, and is usually preferably about 100 to 1500 parts by mass per 100 parts by mass of the (meth)acrylic polymer (a).

[0104] <Conductive elastomer> The conductive elastomer of this embodiment can be formed using the composition of this embodiment. Specifically, by applying energy such as heat to the composition of this embodiment and crosslinking the (meth)acrylic polymer (a) with the metal chelate compound (b), the conductive elastomer of this embodiment can be formed, in which the (meth)acrylic polymer (a) (i.e., polymer X) having crosslinking sites crosslinked via the chelate metal forms a polymer matrix, and the conductive material (c) is dispersed in the matrix. Note that the shape of the elastomer of this embodiment, such as width, thickness, and length, is not particularly limited.

[0105] <Polymer X> As described above, the polymer X can be obtained by crosslinking the (meth)acrylic polymer (a) with the metal chelate compound (b). Examples of such polymer X include polymers having units A and units B, where the units A are crosslinked via the chelating metal described above, with a content of units A of 0.5 to 5 mol % and a content of units B of 95 to 99.5 mol %. Specific examples of polymer X include polymers having units A1 derived from acrylic acid and units B1 derived from isostearyl acrylate, where the units A are crosslinked via at least one selected from Al and Ti, with a content of units A1 of 0.5 to 5 mol % and a content of units B1 of 95 to 99.5 mol %, using a metal chelate compound containing Al or Ti as the chelating metal and isostearyl acrylate as the chelating agent portion.

[0106] <Method of manufacturing conductive elastomer> The conductive elastomer of this embodiment can be produced, for example, by using the composition of this embodiment containing a (meth)acrylic polymer (a), a metal chelate compound (b), a conductive material (c), and a chelating agent (d), and, if necessary, dissolving the (meth)acrylic polymer (a) in a solvent and / or a chelating agent (d) to obtain a resin solution. Next, by applying energy such as heat to the obtained composition, the conductive elastomer of this embodiment can be obtained, in which the conductive material (c) is dispersed in the polymer X. The composition of this embodiment may contain other additives, if necessary.

[0107] An example of the method for producing the conductive elastomer of this embodiment is not particularly limited, but may be, for example, a resin solution preparation step of dissolving at least the (meth)acrylic polymer (a) in a solvent or a chelating agent (d) to obtain a resin solution; a composition preparation step of adding a metal chelate compound (b), a conductive material (c), and a chelating agent (d) to the resin solution to prepare a conductive elastomer-forming composition; a heating step of heating the conductive elastomer-forming composition to synthesize a (meth)acrylic polymer (a) (polymer X) having crosslinking sites crosslinked via metal atoms; A manufacturing method including the steps of:

[0108] The resin solution preparation step is a step of dissolving the (meth)acrylic polymer (a) in a solvent or chelating agent (d) to obtain a resin solution. The solvent may be any of the solvents listed above as examples of solvents that can be used in the composition of this embodiment. Furthermore, the chelating agent (d) that can be used instead of the solvent may be, for example, ethyl acetoacetate, although this depends on the type of (meth)acrylic polymer (a). When the chelating agent (d) is used as a solvent in the resin solution preparation step, the addition of the chelating agent (d) may be omitted in the composition preparation step described below.

[0109] The composition preparation step is a step of preparing the composition of this embodiment by adding a metal chelate compound (b), a conductive material (c), and a chelating agent (d) to a resin solution containing a (meth)acrylic polymer (a). However, the order in which the components in the composition of this embodiment are mixed is arbitrary; for example, these components may be mixed all at once. That is, in the resin solution preparation step, the metal chelate compound (b) and the like may be added to a solvent together with the (meth)acrylic polymer (a), and the resin solution preparation step and the composition preparation step may be carried out simultaneously.

[0110] The heating step is a step of heating the composition of this embodiment to promote a crosslinking reaction between the (meth)acrylic polymer (a) and the metal chelate compound (b), thereby synthesizing a (meth)acrylic polymer (a) (polymer X) having crosslinked moieties crosslinked via metal atoms. The heating conditions in the heating step are not particularly critical, but from the viewpoints of the decomposition temperature of the metal chelate compound (b) and maintaining the coordinate bond between the metal atom and the oxygen atom in polymer X, the heating temperature is, for example, preferably 60 to 150°C, more preferably 80 to 140°C, and particularly preferably 100 to 130°C. The heating time is determined appropriately depending on the heating temperature, but from the viewpoint of promoting the volatilization of the solvent and / or chelating agent, it is, for example, preferably 10 to 90 minutes, more preferably 20 to 80 minutes, and particularly preferably 30 to 70 minutes.

[0111] The composition of the present embodiment obtained in the composition preparation step can be used as a conductive material precursor. For example, when a conductive film is produced using the conductive material elastomer, the conductive material precursor is applied to a release film, and the resulting coating film is heated in a heating step to produce the conductive film. The method for producing the conductive film will be described later.

[0112] Furthermore, the solvent and / or chelating agent (d) used in the resin solution preparation step preferably has a boiling point that allows it to volatilize at the heating temperature during the heating step. When a solvent that can volatilize by the heat of the heating step is used in the resin solution preparation step, there is no need to provide a separate solvent removal step such as a drying step after the heating step, and production efficiency can be improved. The boiling point of the solvent and / or chelating agent (d) does not need to be equal to or higher than the heating temperature of the heating step, and a solvent and / or chelating agent (d) having a boiling point lower than the heating temperature of the heating step may be used.

[0113] As described above, the conductive elastomer of this embodiment may contain additives to the extent that the object of this embodiment is not impaired. Examples of additives include dispersants, other polymers, neutralizing agents, colorants, UV inhibitors, and antioxidants, but this embodiment is not limited to these examples.

[0114] The conductive elastomer of this embodiment may contain an appropriate amount of a viscosity modifier to adjust its viscosity. Examples of the viscosity modifier include acrylic polymers, acrylonitrile polymers, (meth)acrylamide polymers, polyamides, vinyl chloride polymers, urethane polymers, polyesters, and carboxymethyl cellulose, but this embodiment is not limited to these examples. These other polymers may be used alone or in combination of two or more.

[0115] The conductive elastomer of this embodiment may be neutralized with a neutralizing agent, if necessary. Examples of neutralizing agents include inorganic basic compounds such as sodium hydroxide and potassium hydroxide; and organic basic compounds such as monoethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, morpholine, aminomethylpropanol, aminomethylpropanediol, octylamine, tributylamine, and aniline, but the present embodiment is not limited to these examples. These neutralizing agents may be used alone or in combination of two or more.

[0116] The non-volatile content in the conductive elastomer of this embodiment is preferably 3% by mass or more, more preferably 5% by mass or more, from the viewpoint of obtaining a conductive film that is excellent in workability and moldability, as well as in flexibility and elongation over a wide range of the rate of change of electrical resistance, and is preferably 80% by mass or less, more preferably 75% by mass or less, from the viewpoint of improving handleability.

[0117] The amount of nonvolatile content in the conductive elastomer of this embodiment is determined by weighing 1 g of the (meth)acrylic conductive material, drying it in a hot air dryer at a temperature of 130°C for 1 hour, and taking the resulting residue as the nonvolatile content, and calculating the formula: [Non-volatile content (mass%) in (meth)acrylic conductive material] = ([mass of residue] ÷ [(meth)acrylic conductive material 1 g]) × 100 This means the value calculated based on

[0118] <Physical properties of conductive elastomers> From the viewpoint of obtaining a conductive film having excellent flexibility over a wide range of the rate of change of electrical resistance, the Young's modulus of the conductive elastomer of this embodiment is preferably 30 MPa or less, more preferably 20 MPa or less, even more preferably 10 MPa or less, and particularly preferably 5 MPa or less. In this embodiment, the Young's modulus of the conductive elastomer can be measured based on the method described in the following examples.

[0119] From the viewpoint of obtaining a conductive film having excellent extensibility over a wide range of the rate of change in electrical resistance, the elongation of the conductive elastomer of this embodiment is preferably 400% or more, more preferably 500% or more, even more preferably 1000% or more, and particularly preferably 1500% or more. Note that in this embodiment, the elongation of the conductive film is a value measured based on the method described in the following examples.

[0120] The volume resistivity of the conductive elastomer of this embodiment can be set to any value by adjusting the type and amount of the conductive material (c) used depending on the application of the conductive elastomer. Although not particularly limited, for example, when silver particles are used as the conductive material (c), the volume resistivity can be set to 1.0 × 10 -3 Ω·cm or less is preferable, and 1.0×10 -4 Further, when carbon nanotubes are used as the conductive material (c), the electrical resistance is preferably 50 Ω·cm or less, and more preferably 1 Ω·cm or less.

[0121] The resistance change rate at 100% elongation of the conductive elastomer of this embodiment is, for example, the resistance (Ω; R 1 ) and the resistance value (Ω; R 10 ) and the ratio [R 10 / R 1The lower the rate of change in resistance value at 100% elongation of the conductive elastomer, the more the decrease in conductivity due to repeated stretching is suppressed. The rate of change in resistance value at 100% elongation is, for example, preferably 2 times or less, and more preferably 1.5 times or less.

[0122] <<Applications of Conductive Elastomers>> The shape of the conductive elastomer can be appropriately designed depending on the intended use. The conductive elastomer can be used in various forms, such as a sheet-like conductive film or a laminate.

[0123] (Conductive film) The conductive film may be formed, for example, by applying the composition of the present embodiment to a substrate and drying it, but the present embodiment is not limited to this example.

[0124] Examples of the substrate include commonly used papers such as fine paper, kraft paper, crepe paper, and glassine paper; substrates made of resins such as polyethylene, polypropylene, polyester, polystyrene, polyvinyl chloride, and cellophane; and textile products such as woven fabric, nonwoven fabric, and cloth; however, the present embodiment is not limited to only these examples.

[0125] Methods for applying the composition of this embodiment to a substrate include, for example, commonly used methods such as a knife coater, slot die coater, lip coater, roll coater, flow coater, spray coater, bar coater, and dipping, but this embodiment is not limited to these examples. When applying the composition of this embodiment to a substrate, it may be applied directly to the substrate, or it may be applied to release paper or the like and then the applied material may be transferred onto the substrate. By applying the composition of this embodiment in this way and then drying it, a conductive film can be formed on the substrate.

[0126] The thickness of the composition of this embodiment to be applied to a substrate cannot be determined in general because it varies depending on the types of (meth)acrylic polymer (a) and conductive material (c), and is therefore preferably determined appropriately depending on the desired thickness of the conductive film to be formed on the substrate. The thickness of the (meth)acrylic conductive material to be applied to a substrate is usually about 1 to 1000 μm, from the viewpoint of obtaining a conductive film excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance.

[0127] Methods for drying the composition of the present embodiment after it has been applied to a substrate include, for example, hot air and far-infrared radiation, but the present embodiment is not limited to these examples.

[0128] The shape and size of the conductive film of this embodiment are not particularly limited and can be determined as desired depending on the intended use of the conductive film. Examples of the shape of the conductive film include a circle, an ellipse, a triangle, a square, and a rectangle, but the present embodiment is not limited to these examples. An example of the size of the conductive film is a circle with a diameter of 1 to 20 mm.

[0129] The thickness of the conductive film varies depending on the application of the conductive film and cannot be determined in general terms. Therefore, it is preferable to determine the thickness appropriately depending on the application. However, from the viewpoint of obtaining a conductive film that is excellent in flexibility and elongation over a wide range of the rate of change of electrical resistance, the thickness is usually preferably about 1 to 1000 μm, more preferably about 5 to 500 μm, and even more preferably about 10 to 100 μm.

[0130] The conductive elastomer of this embodiment obtained as described above is formed using a conductive elastomer-forming composition containing a (meth)acrylic polymer (a), a conductive material (c), a metal chelate compound (b), and a chelating agent (d), and by applying energy such as heat to the composition, the (meth)acrylic polymer (a) can be crosslinked by the metal chelate compound (b), thereby achieving the excellent effect of suppressing a decrease in conductivity due to repeated stretching.

[0131] Therefore, the conductive elastomer of this embodiment is expected to be used in conductive parts of, for example, sensors, wiring, electrodes, substrates, power generation elements, speakers, microphones, noise cancellers, transducers, artificial muscles, small pumps, medical instruments, etc. used in actuators, industrial robots, etc. Among these, the conductive film of this embodiment is suitable for use in conductive parts of actuators with large displacements, because the decrease in conductivity due to repeated stretching is suppressed.

[0132] (actuator) An actuator will be described below as an example of an electrical device using a conductive elastomer. However, the present embodiment is not limited to the embodiment described below.

[0133] Fig. 1 is a schematic plan view showing one example of the actuator of this embodiment. Fig. 2 is a schematic cross-sectional view of the actuator taken along line AA shown in Fig. 1. Fig. 3 is a schematic view illustrating the displacement of an elastomer.

[0134] 1 and 2, the actuator 1 is formed from a film-like elastomer 2 and a pair of electrodes 3A and 3B. The elastomer 2 and the electrodes 3A and 3B can be bonded together using, for example, a conductive paste (not shown). Examples of the conductive paste include conductive pastes containing conductive fillers such as carbon and silver.

[0135] The thickness of the elastomer 2 is preferably 1 to 100 μm, more preferably 1 to 80 μm, even more preferably 1 to 50 μm, and even more preferably 1 to 30 μm, from the viewpoint of enabling the actuator 1 to exhibit a large displacement even when a low voltage is applied.

[0136] As shown in FIG. 2, electrodes 3A and 3B are arranged on both sides of the elastomer 2, facing each other. Each electrode is made of an electrode material. Examples of electrode materials include indium tin oxide (ITO), antimony tin oxide (ATO), fluorine-doped tin oxide (FTO), fluorine tin oxide (FTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), tin oxide (NESA), indium zinc oxide (IZO), metals and metal oxides such as silver oxide, vanadium oxide, molybdenum oxide, gold, silver, platinum, copper, indium, and chromium; silicon-based materials such as polycrystalline silicon and amorphous silicon; and carbon materials such as carbon black, graphite, and glassy carbon. However, this embodiment is not limited to these examples. These electrode materials may be used alone or in combination of two or more.

[0137] The shape, size, and thickness of the electrodes 3A and 3B are not particularly limited and can be determined as desired depending on the application of the actuator 1. Examples of the shape of the electrodes 3A and 3B include circular, elliptical, triangular, square, and rectangular. An example of the size of the electrodes 3A and 3B is a circular shape with a diameter of 1 to 20 mm. The thickness of the electrodes 3A and 3B is not particularly limited, but is typically about 50 to 500 μm.

[0138] A terminal 4A is disposed on the outer circumferential surface of electrode 3A in the diameter direction, and a terminal 4B is disposed on the outer circumferential surface of electrode 3B in the diameter direction. Terminals 4A and 4B are connected to a power source 6 via conductors 5A and 5, respectively.

[0139] When a voltage is applied to electrodes 3A and 3B by power supply 6, an electrostatic attraction is generated between the electrodes, and as shown in Fig. 3, elastomer 2 is compressed in the direction indicated by the thick arrow in Fig. 3, so that the thickness (W in Fig. 2) of elastomer 2 decreases and elastomer 2 is stretched in the width direction (direction indicated by the thin arrow in Fig. 3). At this time, electrodes 3A and 3B are stretched in the width direction together with elastomer 2.

[0140] By attaching a marker 7 to the electrode 3A, the displacement of the actuator 1 when a voltage is applied to the electrodes 3A and 3B can be measured by a displacement meter 8. [Example]

[0141] Next, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to only these examples.

[0142] [Example 1] <Preparation of polymer solution> (Synthesis of (meth)acrylic polymer (a))] A monomer component containing a polymerization initiator was obtained by mixing isostearyl acrylate ("ISTA", 5.6 g), 2,2,2-trifluoroethyl acrylate ("V#3F", 6.5 g, manufactured by Osaka Organic Chemical Industry Ltd., trade name "Viscoat 3F"), acrylic acid ("AA", 0.065 g), and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (0.015 g, manufactured by BASF, trade name "Irgacure (registered trademark) TPO") as a polymerization initiator. The obtained monomer component was poured into a transparent glass mold (length: 100 mm, width: 100 mm, depth: 2 mm), and then the monomer component was irradiated with a dose of 0.84 mW / cm 2 The monomer components were bulk polymerized for 1 hour under irradiation with ultraviolet light so that the temperature became 100°C, thereby obtaining a (meth)acrylic polymer (a).

[0143] (Preparation of resin solution) The obtained (meth)acrylic polymer (a) (2.20 g) was mixed and dissolved in a solvent (isododecane (solvent; 24 parts by mass), and a mixture of 1,2,4-trimethylbenzene (solvent; 8 parts by mass) and ethyl acetoacetate (chelating agent (d); 8 parts by mass)) (7.80 g) to obtain an acrylic resin solution.

[0144] <Preparation of conductive film> (Preparation of Conductive Material Precursor) The obtained acrylic resin solution (7.70 g) was mixed with silver filler (7.20 g, manufactured by Fukuda Metal Foil & Powder Co., Ltd., product name "AgC-A") and aluminum tris(ethylacetoacetate) (0.10 g, manufactured by Kawaken Fine Chemicals Co., Ltd., product name "ALCH-TR") as a metal chelate compound using a mixer manufactured by Kurabo Industries Ltd. (product name "Mazerustar") to obtain a conductive material precursor.

[0145] (paint film formation) The obtained conductive material precursor was applied to a release film (a release polyethylene terephthalate film (manufactured by Mitsui Chemicals Tohcello, Inc., product name "Separator SP-PET PET-01-Bu") to form a coating film.

[0146] (Heating process: Preparation of conductive film) The resulting coating was heated in an oven at 120°C for 60 minutes to obtain a conductive film (conductive elastomer) with a thickness of approximately 38 µm.

[0147] <Examples 2 to 6, Comparative Examples 1 to 5> Except for changing the compositions according to the table below, conductive films of each example and comparative example were obtained in the same manner as in Example 1. In Comparative Example 3, a blocked cyanate was used as a crosslinking agent instead of a metal chelate compound.

[0148] [Evaluation method] The resulting conductive film was subjected to the following measurements, and the results are shown in the table below.

[0149] [Volume resistivity measurement] The obtained conductive film was cut into 20 mm squares, and the volume resistivity (Ω·cm) of the film was measured using a low resistivity meter (Loresta GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) by the four-terminal method. Note that the lower the volume resistivity, the better the results.

[0150] [Measurement of resistance value after elongation and rate of change in resistance value] The obtained conductive film was cut into a length of 40 mm and a width of 10 mm to obtain a test piece, which was then attached to a tensile tester (manufactured by A&D Co., Ltd., product number: Tensilon RTG-1310) with a chuck distance of 10 mm. After that, the distance between the chucks was extended to 20 mm, held for 30 seconds, and then returned to 10 mm (all at a tensile speed of 50 mm / min). This cycle was repeated 10 times, and the resistance value (Ω:R 1 ), resistance value after 10 cycles (Ω:R 10 ) was measured using a digital multimeter (manufactured by Sanwa Denki Keiki Co., Ltd.; product name PC773). From the measured values, the resistance change rate [R 10 / R 1 The lower the resistance value and the rate of change in resistance, the better the results. In particular, the lower the rate of change in resistance, the more the decrease in conductivity due to repeated expansion and contraction is suppressed.

[0151] [Young's modulus, tensile strength, and elongation measurements] Test specimens were obtained by punching out a dumbbell-shaped No. 7 specimen as specified in JIS K6251 (2017) 6.1. The obtained test specimen was attached to a tensile testing machine (A&D Corporation, Model: Tensilon RTG-1310) with a chuck distance of 19 mm, and a tensile load was applied at a pulling rate of 50 mm / min until the test specimen broke. The Young's modulus, stress at break (tensile strength), and elongation were measured. The elongation of the film obtained above was calculated using the following formula: Formula: [Film elongation (%)] = [Test piece length at break (mm) - Original test piece length (mm)] ÷ [Original test piece length (mm)] x 100

[0152] [Table 1]

[0153] [Table 2]

[0154] The abbreviations for the compositions of the (meth)acrylic polymer (a) in each table are as follows: EA: Ethyl acrylate AA: acrylic acid V#3F: 2,2,2-trifluoroethyl acrylate (Viscoat 3F) ISTA: Isostearyl acrylate HOA-MS: 2-acryloyloxyethyl succinate 4HBA: 4-hydroxybutyl acrylate

[0155] Comparisons between Example 1 and Comparative Example 2 or Comparative Example 3, between Example 2 and Comparative Example 1, between Example 4 and Comparative Example 4, and between Example 5 and Comparative Example 5 reveal that, compared to the comparative examples that do not use a metal chelate compound (crosslinking agent) (Comparative Example 3 uses blocked cyanate as a crosslinking agent instead of a metal chelate compound), the conductive films of the examples have a particularly low rate of change in resistance value, and the decrease in conductivity due to repeated stretching is suppressed.

[0156] The disclosure of Japanese Patent Application No. 2021-175653, filed on October 27, 2021, is incorporated herein by reference in its entirety. In addition, all publications, patent applications, and technical standards mentioned in the specification are herein incorporated by reference to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. [Industrial Applicability]

[0157] The conductive elastomer of the present invention is useful as a dielectric elastomer, although it is not particularly limited thereto, and is expected to be used, for example, in actuators, sensors used in industrial robots, etc., power generation elements, speakers, microphones, noise cancellers, transducers, artificial muscles, small pumps, medical instruments, etc. [Explanation of symbols]

[0158] 1: Actuator, 2: Elastomer, 3A, 3B: Electrode, 4A, 4B: Terminal, 5A, 5B: Conductor, 6: Power supply, 7: Marker, 8: Displacement meter

Claims

1. a (meth)acrylic polymer (a) including a unit A having at least one of a carboxyl group and a hydroxyl group, and a unit B1 derived from a (meth)acrylic monomer represented by the following formula (II-1); a metal chelate compound (b); A conductive material (c), a chelating agent (d); and A conductive elastomer-forming composition comprising: 【Chemical 1】 (wherein R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 18 carbon atoms and a halogen atom.)

2. A conductive elastomer-forming composition as described in claim 1, wherein the (meth)acrylic polymer (a) further contains a unit B2 derived from a (meth)acrylic monomer represented by the following formula (II-2): 【Chemistry 2】 (wherein R 2 represents an alkyl group having 1 to 18 carbon atoms).

3. A conductive elastomer-forming composition as described in claim 1, wherein the unit A is a unit derived from a (meth)acrylic monomer represented by the following formula (I): 【Chemistry 3】 (In the formula, R 1 represents a hydrogen atom or a methyl group, X represents a carboxyl group or a hydroxyl group, Z represents an alkyl group having 1 to 10 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms, and the alkyl group and the alkoxyalkyl group may contain an ester bond, and n represents 0 or 1.)

4. A conductive elastomer-forming composition as described in claim 1, containing a solvent.

5. A conductive elastomer formed using the conductive elastomer-forming composition according to any one of claims 1 to 4.

6. A conductive elastomer comprising: a (meth)acrylic polymer (a) having a unit A having at least one of a carboxyl group and a hydroxyl group, and a unit B1 derived from a (meth)acrylic monomer represented by the following formula (II-1); and a conductive material (c), wherein the (meth)acrylic polymer (a) has a crosslinked site formed by crosslinking via a metal atom: 【Chemistry 4】 (wherein R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 18 carbon atoms and a halogen atom.)

7. A conductive elastomer as described in Claim 6, wherein the (meth)acrylic polymer (a) further contains a unit B2 derived from a (meth)acrylic monomer represented by the following formula (II-2): 【Chemistry 5】 (wherein R 2 represents an alkyl group having 1 to 18 carbon atoms).

8. 8. The conductive elastomer according to claim 6, wherein the metal atom is at least one selected from Al and Ti.

9. The conductive elastomer according to claim 6 or 7, which has a Young's modulus of 30 MPa or less.

10. Units A1 derived from acrylic acid; and units B1 derived from isostearyl acrylate, the units A1 are crosslinked via at least one selected from Al and Ti, the content ratio of the unit A1 is 0.1 to 10 mol %, The content ratio of the unit B1 is 90 to 99.9 mol %. Polymer.

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