Composition having magnetostrictive properties and cured product thereof

Abstract

A composition having magnetostrictive properties and comprising: a compound (component (P)) including a polymerizable group; a powdery magnetostrictive material (component (M)); and a radical polymerization initiator (component (R)).

Description

[Technical Field]

[0001] The present invention relates to a composition having magnetostrictive properties and a cured product thereof. This application claims priority based on Japanese Patent Application No. 2021-031516, filed in Japan on March 1, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Magnetostrictive materials are materials that deform slightly when a magnetic field is applied, and the phenomenon in which this deformation occurs is called "magnetostriction." Conversely, when a magnetostrictive material is deformed by applying force, the magnetic field inside the material changes, resulting in an inverse magnetostriction phenomenon. This change in magnetic field due to the inverse magnetostriction phenomenon can be used in sensors and vibration power generation. Magnetostriction is a characteristic of ferromagnetic materials. Ferromagnetic materials such as Fe (iron), Co (cobalt), and Ni (nickel) can change their shape by approximately 0.01 to 0.0001% of their original shape. Also known as magnetostrictive materials with high magnetostrictive properties, known as giant magnetostriction, are Terfenol-D (Fe-Dy (dysprosium)-Tb (terbium) alloy), Galfenol (Fe-Ga (gallium) alloy), and Fe-Co alloy.

[0003] As a magnetostrictive material, a composite reinforced magnetostrictive composite material has been proposed in which a wire made of an iron-based magnetostrictive alloy is embedded as a filler in a base material (matrix). Specifically, an FeCo fiber-reinforced composite material has been disclosed in which FeCo fibers are arranged in one direction in a mold as a filler, and an epoxy resin matrix is ​​poured into the mold and cured under a predetermined stress (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-163119 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the composite-reinforced magnetostrictive composite material described in Patent Document 1, a plurality of wires made of an iron-based magnetostrictive alloy must be aligned in the same direction, which requires a complicated operation.

[0006] As described above, magnetostrictive materials, in which the surrounding magnetic field changes when stress is applied, are expected to be used as energy harvesters that use repeated stress loads or as stress sensors. However, magnetostrictive materials with high magnetostrictive properties, such as Terfenol-D and Galfenol, are brittle and therefore have difficulty withstanding repeated stress loads.Fe-Co alloys, which have slightly inferior magnetostrictive properties, have slightly better mechanical properties but still lack sufficient fatigue properties. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel magnetostrictive composite material having magnetostrictive properties. [Means for solving the problem]

[0007] The present inventors have developed a new magnetostrictive composite material in which a powdered magnetostrictive material is dispersed in a matrix that hardens by radical polymerization. That is, in order to solve the above-mentioned problems, the present invention employs the following configuration.

[0008] [1] A composition having magnetostrictive properties, comprising: (P) component: a compound containing a polymerizable group; (M) component: a powdered magnetostrictive material; and (R) component: a radical polymerization initiator.

[0009] [2] The composition according to [1], wherein the component (M) is a group of particles made of an iron-based magnetostrictive alloy and having an average particle size of 5 μm or more and 50 μm or less.

[0010] [3] The composition according to [1] or [2], wherein the content of the (M) component is 40% by volume or more and 60% by volume or less relative to the total volume of the (P) component, the (M) component, and the (R) component, and the composition has negative magnetostriction properties.

[0011] [4] The composition according to any one of [1] to [3], wherein the content of the (R) component is 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the (P) component.

[0012] [5] The composition according to any one of [1] to [4], wherein the component (P) is a thermosetting resin containing a polymerizable unsaturated double bond.

[0013] [6] The composition according to any one of [1] to [5], wherein the component (P) is a thermosetting elastomer having a glass transition temperature of −130° C. or higher and −5° C. or lower.

[0014] [7] The composition according to [6], wherein the thermosetting elastomer is a urethane (meth)acrylate.

[0015] [8] The composition according to [7], wherein the thermosetting elastomer is a urethane (meth)acrylate having a weight average molecular weight of 2,000 or more and 30,000 or less, obtained by reacting a polycaprolactone polyol having a number average molecular weight of 300 or more and 900 or less, an aliphatic or alicyclic diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0016] [9] A cured product obtained by curing the composition according to any one of [1] to [8]. [Effects of the Invention]

[0017] According to the present invention, a novel magnetostrictive composite material having magnetostrictive properties can be provided. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic diagram showing a method for evaluating magnetostriction characteristics in the present example. [Figure 2]These are schematic diagrams of the (M) component particles dispersed in a cured sample when viewed from above before and after application of a magnetic field. In Figure 2, the arrow (z-axis direction) indicates the direction of magnetic field application. Figure 2(A) shows the state of the (M) component particles dispersed in the cured sample before application of a magnetic field. Figure 2(B) shows the state of the (M) component particles dispersed in the cured sample after application of a magnetic field (positive magnetostriction). Figure 2(C) shows the state of the (M) component particles dispersed in the cured sample after application of a magnetic field (negative magnetostriction). [Figure 3] This figure shows the change in shape of the (M) component particles dispersed in the cured sample when a magnetic field was applied to the cured product of the composition of Example 6. The vertical axis shows magnetostriction, λ (ppm), and the horizontal axis shows magnetic flux density, B (mT). [Figure 4] This figure shows the change in shape of the (M) component particles dispersed in the cured sample when a magnetic field was applied to the cured product of the composition of Example 3. The vertical axis shows magnetostriction, λ (ppm), and the horizontal axis shows magnetic flux density, B (mT). DETAILED DESCRIPTION OF THE INVENTION

[0019] (Magnetostrictive composition) The composition of this embodiment is a magnetostrictive composite material having magnetostrictive properties, containing a component (P): a compound containing a polymerizable group, a component (M): a powdered magnetostrictive material, and a component (R): a radical polymerization initiator.

[0020] The magnetostrictive properties of this magnetostrictive composite material refer to at least the property of changing dimensions when a magnetic field is applied, and the property of changing the magnetic field inside the material when pressure is applied. In the former property, when a magnetic field is applied in one direction, the phenomenon of expansion in that same direction is called "positive magnetostriction," and the phenomenon of contraction in that same direction is called "negative magnetostriction." The composition of this embodiment not only exhibits positive magnetostriction but can also exhibit negative magnetostriction.

[0021] The form of the composition of this embodiment is not particularly limited, and a preferred form is one in which a powdered magnetostrictive material is dispersed in the composition. The composition of the present embodiment may be in the form of, for example, a dispersion or a solution, or may be in the form of a powder or a lump.

[0022] <Component (P): Compound containing a polymerizable group> The component (P) is polymerized by the action of the component (R) when the composition is cured, and can form the base material (matrix) of the cured product. The "polymerizable group" in component (P) is a group that enables a compound containing the polymerizable group to polymerize by radical polymerization or the like, and refers to a group that contains a multiple bond between carbon atoms, such as a polymerizable unsaturated double bond.

[0023] The "polymerizable group" in component (P) is not particularly limited, but is preferably a radically polymerizable group. The multiple bond between carbon atoms may be a polymerizable carbon-carbon double bond or a polymerizable carbon-carbon triple bond, but is preferably a polymerizable carbon-carbon double bond. Examples of the polymerizable carbon-carbon double bond include a methacryloyl group and an acryloyl group. The polymerizable group contained in the component (P) may be of one type or of two or more types.

[0024] From the viewpoint of applications that utilize magnetostrictive properties, the component (P) is preferably a thermosetting resin, and more preferably a thermosetting resin containing a polymerizable unsaturated double bond.

[0025] The number of polymerizable groups contained in the component (P) can be determined appropriately depending on the intended use, etc. For example, the component (P) may be a compound containing 1 to 6 polymerizable groups. From the viewpoints of durability against repeated stress loads, low elastic modulus, etc., a compound containing 1 to 5 polymerizable groups is preferred, a compound containing 1 to 4 polymerizable groups is more preferred, and a compound containing 1 or 2 polymerizable groups is particularly preferred.

[0026] Furthermore, from the viewpoints of durability against repeated stress loads and low elastic modulus, the component (P) is preferably a thermosetting resin with a low glass transition temperature, and more preferably a thermosetting resin with a glass transition temperature of 0°C or lower. In this specification and claims, the term "glass transition temperature" refers to a value measured by a test method in accordance with JIS K 7244-1:1998 (ISO 6721-1:1994).

[0027] Among the above, a thermosetting elastomer is preferred as component (P) from the viewpoints of durability against repeated stress loads, a low modulus of elasticity, etc. A thermosetting elastomer is likely to have a low modulus of elasticity after curing.

[0028] Component (P) is more preferably a thermosetting elastomer with a glass transition temperature of 0°C or lower, even more preferably a thermosetting elastomer with a glass transition temperature of -130°C or higher and -5°C or lower, particularly preferably a thermosetting elastomer with a glass transition temperature of -100°C or higher and -5°C or lower, and most preferably a thermosetting elastomer with a glass transition temperature of -50°C or higher and -10°C or lower. When the glass transition temperature of the thermosetting elastomer for component (P) is equal to or lower than the upper limit of the preferred range, the resulting cured product tends to have a low elastic modulus. On the other hand, when the glass transition temperature is equal to or higher than the lower limit of the preferred range, the resulting cured product has increased strength.

[0029] <Thermosetting elastomer> Examples of thermosetting elastomers include resin-based elastomers, and urethane (meth)acrylate is a preferred example. This urethane (meth)acrylate can be synthesized by an addition reaction between a polyol (component (O)), a polyisocyanate compound (component (I)), and a hydroxyl group-containing (meth)acrylate, for example, by carrying out a known urethane reaction. Here, "(meth)acrylate" is a concept that encompasses methacrylate and acrylate, and means either methacrylate or acrylate.

[0030] The polyol (component (O)) is a compound having two or more hydroxy groups (—OH). The component (O) is not particularly limited, and any compound generally used in the production of urethane resins can be used without particular limitation. The component (O) may be an aliphatic polyol or an aromatic polyol, or may be a low molecular weight polyol or a high molecular weight polyol.

[0031] In this specification and claims, "aliphatic" is a relative concept to aromatic, and is defined as meaning a non-aromatic group, a non-aromatic compound, etc. "Alicyclic" refers to a non-aromatic group or a non-aromatic compound that has a cyclic structure.

[0032] Specific examples of low molecular weight polyols include ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, alkanediols having 7 to 22 carbon atoms, diethylene glycol, triethylene glycol, dipropylene glycol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, alkane-1,2-diols having 17 to 20 carbon atoms, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. Examples of suitable alcohols include dihydric alcohols such as 1,4-cyclohexanediol, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2,6-dimethyl-1-octene-3,8-diol, and bisphenol A; trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as tetramethylolmethane (pentaerythritol) and diglycerin; pentahydric alcohols such as xylitol; hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altritol, inositol, and dipentaerythritol; heptahydric alcohols such as perseitol; and octahydric alcohols such as sucrose. Among these, diols having a number average molecular weight of 50 to 300 are preferred, and ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol are more preferred. These may be used alone or in combination of two or more.

[0033] Specific examples of polymer polyols include phenolic resins, resins containing a hydroxystyrene skeleton, polyester polyols, polyether polyols, polyether ester polyols, polyesteramide polyols, acrylic polyols, polycarbonate polyols, polyhydroxyl alkanes, polyurethane polyols, polycaprolactone polyols, and vegetable oil-based polyols. Among these, polycaprolactone polyols are preferred. These may be used alone or in combination of two or more. The number-average molecular weight of the polymer polyol is preferably 300 to 2000, more preferably 300 to 1500, and even more preferably 300 to 900.

[0034] The polyisocyanate compound (component (I)) may be an aliphatic diisocyanate, an alicyclic diisocyanate, an aromatic diisocyanate, or a mixture thereof. Hexamethylene diisocyanate is preferred as the aliphatic diisocyanate. The alicyclic diisocyanate is preferably hydrogenated xylene diisocyanate, isophorone diisocyanate, 1,3-bisisocyanatomethylcyclohexane, 1,4-bisisocyanatomethylcyclohexane, norbornane diisocyanate, or dicyclohexylmethane-4,4'-diisocyanate. The aromatic diisocyanate is preferably 4,4-diphenylmethane diisocyanate. Of these, the component (I) is preferably an aliphatic or alicyclic diisocyanate. These may be used alone or in combination of two or more.

[0035] The hydroxyl group-containing (meth)acrylate has at least one hydroxyl group and one or more (meth)acryloyl groups in one molecule. Examples of the hydroxyl group-containing (meth)acrylate include unsaturated fatty acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone adducts of the above unsaturated fatty acid hydroxyalkyl esters (average number of moles added: 1 to 10); polyethylene glycol (average number of moles added: 1 to 10) mono(meth)acrylate, polypropylene glycol (average number of moles added: 1 to 10) mono(meth)acrylate; pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, and the like. (meth)acrylate, pentaerythritol tri(meth)acrylate; dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate; glycerin mono(meth)acrylate, diglycerin tri(meth)acrylate, diglycerin di(meth)acrylate; sorbitol mono(meth)acrylate, sorbitol di(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol tetra(meth)acrylate, and the like. Among these, the hydroxyl group-containing (meth)acrylate is preferably an unsaturated fatty acid hydroxyalkyl ester. These hydroxyl group-containing (meth)acrylates may be used alone or in combination of two or more.

[0036] The weight average molecular weight (Mw) of the thermosetting elastomer is preferably 2,000 or more and 30,000 or less, more preferably 2,000 or more and 20,000 or less, and even more preferably 3,000 or more and 10,000 or less. When the Mw of the thermosetting elastomer is at least the lower limit of the preferred range, the strength of the cured product tends to be increased. On the other hand, when the Mw is at most the upper limit of the preferred range, the modulus of elasticity of the cured product tends to be reduced. In this specification and claims, the weight average molecular weight (Mw) of a thermosetting elastomer means a value calculated as a standard polystyrene by GPC measurement.

[0037] Among the above, the thermosetting elastomer is preferably a urethane (meth)acrylate having a weight average molecular weight of 2,000 or more and 30,000 or less, obtained by reacting a polycaprolactone polyol having a number average molecular weight of 300 or more and 900 or less, an aliphatic or alicyclic diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0038] <<Polyfunctional (meth)acrylate compounds>> Furthermore, a polyfunctional (meth)acrylate compound may be used as the component (P). As used herein, "multifunctional" means having two or more functional groups. Multifunctional monomers include, for example, monomers having two functional groups, monomers having three functional groups, monomers having four functional groups, or monomers having even more functional groups. Multifunctional acrylates include diacrylates, triacrylates, and tetraacrylates. Multifunctional methacrylates include dimethacrylates, trimethacrylates, and tetramethacrylates.

[0039] Examples of polyfunctional (meth)acrylate compounds include ethoxylated (3) trimethylolpropane triacrylate, ethoxylated (3) trimethylolpropane trimethacrylate, ethoxylated (6) trimethylolpropane triacrylate, ethoxylated (9) trimethylolpropane triacrylate, ethoxylated (15) trimethylolpropane triacrylate, ethoxylated (20) trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, propoxylated (3) glyceryl triacrylate, propoxylated (3) glyceryl triacrylate, propoxylated (5.5) glyceryl triacrylate, propoxylated (3) trimethylolpropane triacrylate, and propoxylated (6) trimethylolpropane. Examples of the monomer include trifunctional monomers such as trimethylolpropane triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tris-(2-hydroxyethyl)-isocyanurate triacrylate, tris-(2-hydroxyethyl)-isocyanurate trimethacrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, and EO,PO-modified trimethylolpropane tri(meth)acrylate; tetrafunctional monomers such as ditrimethylolpropane tetraacrylate, ethoxylated (4) pentaerythritol tetraacrylate, and pentaerythritol tetra(meth)acrylate; and pentafunctional or higher monomers such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

[0040] The component (P) may be used alone or in combination of two or more.

[0041] <(M) component: powdered magnetostrictive material> The (M) component is a powdered material that deforms slightly when a magnetic field is applied. The average particle size of the particle group of component (M) is preferably 5 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and even more preferably 5 μm or more and 30 μm or less. When the average particle size of the particle group of component (M) is at least the lower limit of the above-mentioned preferred range, good dispersibility is likely to be obtained, while when it is at most the upper limit of the above-mentioned preferred range, good surface smoothness is likely to be obtained. In this specification and the claims, the average particle size of the particle group of component (M) refers to the volume average particle size measured by a test method based on the particle size analysis - laser diffraction and scattering method specified in JIS Z 8825:2013.

[0042] Examples of the (M) component include metal particle groups made of Ni, Fe—Ni alloys, Fe—Co alloys, Fe—Al alloys, Fe—Ga—Al alloys, Fe—Dy—Tb alloys, or Fe—Ga alloys. Among these, the component (M) is preferably an iron-based magnetostrictive alloy, and examples of the iron-based magnetostrictive alloy include Fe-Co alloys, Fe-Ga-Al alloys, Fe-Dy-Tb alloys, and Fe-Ga alloys, and more preferably Fe-Co alloys.

[0043] Specific examples of Fe-Co alloys include Fe (100at%-x-y) -Co x -V y (wherein x=30 to 90 at %, and y=0 to 10 at %).

[0044] Specific examples of Fe-Al alloys include Fe (100at%-x) -Al x (where x=40 to 80 at %).

[0045] Specific examples of Fe-Ga-Al alloys include (Fe (100at%-x-y) -Ga x -Al y ) 100at%-z -C z (where x = 10 to 15 at%, y = 4 to 7 at%, z = 0 to 2 at%); (Fe (100at%-x-y) -Ga x -Al y ) 100at%-z -B z (wherein x=10 to 15 at %, y=4 to 7 at %, and z=0 to 2 at %). The specific example of the Fe—Ga—Al based alloy is an FeGaAl based alloy containing C (carbon) or B (boron).

[0046] An example of an Fe-Dy-Tb alloy is Terfenol-D. An example of an Fe—Ga alloy is Galfenol.

[0047] The component (M) may be used singly or in combination of two or more. Among the above, the component (M) is preferably a particle group made of an iron-based magnetostrictive alloy and having an average particle size of 5 μm to 50 μm, from the viewpoint of magnetostriction characteristics and dispersion stability in the matrix.

[0048] <Component (R): Radical polymerization initiator> Component (R) is a radical polymerization initiator that acts on the polymerizable groups of component (P) to promote the polymerization reaction when the composition is cured, contributing to the formation of the matrix of the cured product. Examples of component (R) include thermal radical polymerization initiators and photoradical polymerization initiators.

[0049] <Thermal radical polymerization initiator> Examples of the thermal radical polymerization initiator include peroxides and azo-based polymerization initiators.

[0050] Examples of the peroxide in the thermal radical polymerization initiator include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, and peroxyester. Specific examples of such peroxides include acetyl peroxide, dicumyl peroxide, tert-butyl peroxide, t-butylcumyl peroxide, propionyl peroxide, benzoyl peroxide (BPO), 2-chlorobenzoyl peroxide, 3-chlorobenzoyl peroxide, 4-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 4-bromomethylbenzoyl peroxide, lauroyl peroxide, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, tert-butyl triphenylperacetate, tert-butyl hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl 4-methoxyacetate, and tert-butyl N-(3-toluyl)carbamate.

[0051] As the peroxide, for example, commercially available products such as those manufactured by NOF Corporation under the trade names "Percumyl (registered trademark)", "Perbutyl (registered trademark)", "Peroyl (registered trademark)" and "Perocta (registered trademark)" can be used.

[0052] Examples of the azo-based polymerization initiator in the thermal radical polymerization initiator include 2,2'-azobispropane, 2,2'-dichloro-2,2'-azobispropane, 1,1'-azo(methylethyl)diacetate, 2,2'-azobis(2-amidinopropane) hydrochloride, 2,2'-azobis(2-aminopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutylamide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylmethylpropionate, 2,2'-azobis-2- ... ,2'-Dichloro-2,2'-azobisbutane, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate) dimethyl (2,2'-azobisisobutyrate dimethyl), 1,1'-azobis(1-methylbutyronitrile-3-sodium sulfonate), 2-(4-methylphenylazo)-2-methylmalonodinitrile, 4,4'-azobis-4-cyanovaleric acid, 3,5-dihydroxymethylphenylazo-2-allylmalonodinitrile, 2,2'-azobis 2-Methylvaleronitrile, 4,4'-azobis-4-cyanodimethylvaleroate, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1'-azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1'-azobis-1-chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'-azobis-1-cyclohexane Examples of suitable bisphenol A copolymers include bisphenol A, bisphenol A tetrahydroheptanenitrile, 1,1'-azobis-1-phenylethane, 1,1'-azobiscumene, ethyl 4-nitrophenylazobenzylcyanoacetate, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotriphenylmethane, 1,1'-azobis-1,2-diphenylethane, poly(bisphenol A-4,4'-azobis-4-cyanopentanoate), and poly(tetraethylene glycol-2,2'-azobisisobutyrate).

[0053] <Photoradical polymerization initiator> Examples of the photoradical polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, bis(4-dimethylaminophenyl) methyl) ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(o-acetyloxime), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 4-benzoyl-4'-methyldimethyl sulfide, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid Ethyl 4-dimethylaminobenzoate, Butyl 4-dimethylaminobenzoate, 4-dimethylamino-2-ethylhexylbenzoic acid, 4-dimethylamino-2-isoamylbenzoic acid, Benzyl-β-methoxyethyl acetal, Benzyl dimethyl ketal, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, Methyl o-benzoylbenzoate, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 1-chloro-4-propoxythioxanthone, Thioxanthene, 2-chlorothioxanthone Santhene, 2,4-diethylthioxanthene, 2-methylthioxanthene, 2-isopropylthioxanthene, 2-ethylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-diphenylanthraquinone, azobisisobutyronitrile, benzoyl peroxide, cumene peroxide, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-Di(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4,5-triarylimidazole dimer, benzophenone, 2-chlorobenzophenone, 4,4'-bisdimethylaminobenzophenone (i.e., Michler's ketone), 4,4'-bisdiethylaminobenzophenone (i.e., ethyl Michler's ketone), 4,4' -Dichlorobenzophenone, 3,3-dimethyl-4-methoxybenzophenone, benzil, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, benzoin-t-butyl ether, acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, dichloroacetophenone, trichloroacetophenone, pt-butylacetophenone, p-dimethylaminoacetophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone, α,α-dichloro-4-phenoxyacetophenone, thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, dibenzosuberone, pentyl-4-dimethylaminobenzoate, 9-phenylacridine, 1,7-bis-(9-acridinyl)heptane, 1,5-bis-(9-acridinyl)pentane, 1,3-bis-(9-acridinyl)propane, p-methoxytriazine, 2,4,6-tris(trichloromethyl)-s-triazine, 2-methyl- 2-[2-(5-methylfuran-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(4-diethylamino-2-methylphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxyphenyl)-4,Examples of such amines include 6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-n-butoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)styrylphenyl-s-triazine, and 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)styrylphenyl-s-triazine.

[0054] The photoradical polymerization initiator may be commercially available, such as "IRGACURE OXE02," "IRGACURE OXE01," "IRGACURE 369," "IRGACURE 651," or "IRGACURE 907" (all trade names, manufactured by BASF); or "NCI-831" (trade name, manufactured by ADEKA Corporation).

[0055] The component (R) may be used alone or in combination of two or more. As the component (R), a thermal radical polymerization initiator is preferred, and among these, an azo-based polymerization initiator is more preferred.

[0056] The total content of the (P), (M), and (R) components in the composition of this embodiment is preferably 80% by volume or more, more preferably 90% by volume or more, even more preferably 95% by volume or more, and may be 100% by volume. A composition of 100% by volume, i.e., a composition consisting of the (P), (M), and (R) components, is particularly preferred.

[0057] In the composition of the present embodiment, the content of the (M) component is preferably 10% by volume or more and 80% by volume or less, and more preferably 20% by volume or more and 70% by volume or less, relative to the total volume (100% by volume) of the (P) component, the (M) component, and the (R) component. If the content of component (M) is within the above-mentioned preferred range, the composition can exhibit both positive and negative magnetostriction. Furthermore, when the content of component (M) is at least the lower limit of the preferred range, magnetostriction properties are more readily exhibited, while when it is at most the upper limit of the preferred range, the strength of the cured product is further increased.

[0058] Furthermore, in the composition of this embodiment, the content of the (M) component is preferably 40% by volume or more and 60% by volume or less, and more preferably 45% by volume or more and 55% by volume or less, relative to the total volume (100% by volume) of the (P), (M) and (R) components, from the viewpoint that the composition is more likely to have negative magnetostriction properties. Thus, in the composition of this embodiment, by controlling the volume fraction of the powdered magnetostrictive material in the cured product to a specific ratio, it is thought that, although the details are not clear, the magnetostrictive material particles magnetized by the application of a magnetic field attract each other, resulting in the composition exhibiting negative magnetostrictive properties.

[0059] Furthermore, in the composition of this embodiment, the content of the (R) component is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 0.1 parts by mass or more and 15 parts by mass or less, and even more preferably 0.5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the (P) component. When the content of the (R) component is at least the lower limit of the above-mentioned preferred range, the efficiency of the polymerization reaction between the (P) components is further improved. On the other hand, when the content is at most the upper limit of the above-mentioned preferred range, the polymerization reaction is sufficiently promoted and the strength of the cured product is further increased.

[0060] <Other ingredients> The composition of the present embodiment may contain, in addition to the component (P), the component (M), and the component (R), other components in addition to these, as necessary. Examples of other components besides the component (P), the component (M), and the component (R) include solvents, surfactants, dispersants, antifoaming agents, antioxidants, fragrances, plasticizers, and the like.

[0061] [Method for preparing the composition] The composition of the present embodiment can be prepared by a production method that includes a step of mixing the component (P), the component (M), the component (R), and, if necessary, other components.

[0062] Alternatively, the composition of this embodiment can be prepared by a production method including a first step of mixing the (P) component and the (R) component to obtain a mixture (PR), and a second step of mixing the mixture (PR) obtained in the first step with the (M) component. In the second step, the mixing ratio (volume ratio) of the mixture (PR) to the component (M) is preferably component (M) / mixture (PR) = 10 / 90 to 80 / 20, more preferably 20 / 80 to 70 / 30. By controlling the volume ratio of the mixture (PR) to the component (M) within the above-mentioned preferred range, the composition can exhibit both positive and negative magnetostriction. Furthermore, since the composition can exhibit negative magnetostriction, in the second step, the mixing ratio (volume ratio) of the mixture (PR) to the component (M) is preferably component (M) / mixture (PR) = 40 / 60 to 60 / 40, and more preferably 45 / 55 to 55 / 45.

[0063] (cured product) The cured product of this embodiment is obtained by curing the above-mentioned (composition having magnetostrictive properties). The shape of the cured product is not particularly limited, and examples thereof include a plate, a cylinder, and a prism.

[0064] [Method of manufacturing the cured product] The cured product of this embodiment can be produced, for example, by a production method including a step of pouring the above-described composition into a mold of a predetermined shape and performing a heat curing treatment. The heat curing treatment may be carried out in one operation or in two or more operations.

[0065] As explained above, the composition of this embodiment is a magnetostrictive composite material having magnetostrictive properties, containing a polymerizable group-containing compound (component P), a powdered magnetostrictive material (component M), and a radical polymerization initiator (component R). This is a novel magnetostrictive composite material that employs a powdered magnetostrictive material dispersed in a matrix that hardens by radical polymerization. Therefore, unlike conventional magnetostrictive composites in which wires made of iron-based magnetostrictive alloys are embedded in a matrix as fillers, this composite is simple and easy to handle.

[0066] In addition, in the composition of this embodiment, since the polymerizable compound constituting the base material can be selected, it is possible to provide a magnetostrictive composite material in which a magnetostrictive material is combined with various polymers. As such a magnetostrictive composite material, for example, by combining a magnetostrictive material with a polymer having a low modulus of elasticity, it is possible to provide a magnetostrictive composite material that can withstand repeated stress loads. Alternatively, the composition of the present embodiment can be used as a substrate for composite materials, etc. For example, by laminating a fiber-reinforced plastic such as glass fiber-reinforced plastic or carbon fiber-reinforced plastic and a sheet made of the composition of the present embodiment or a cured product thereof and curing the laminate, an FRP bulk having a magnetostrictive effect can be produced.

[0067] Furthermore, in the composition of this embodiment, by controlling the mixing ratio of the polymerizable compound constituting the base material and the powdered magnetostrictive material, it is possible to provide a magnetostrictive composite material that exhibits not only positive magnetostriction (extension in the direction of magnetic field application) but also negative magnetostriction (shortening in the direction of magnetic field application).

[0068] According to the composition of this embodiment, it is expected that the performance of energy harvesting and stress sensors will be further improved when bending stress or bending vibration is utilized, compared to a single magnetostrictive material. The composition of this embodiment is a type of material that undergoes some kind of reaction in response to an external stimulus, and is therefore useful as a smart material. [Example]

[0069] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0070] <Preparation of Composition> When preparing the compositions of each example, the following components (P), (M), and (R) were used. It should be noted that Examples 1 to 4 are reference examples.

[0071] Component (P): Compound containing a polymerizable group Compound (P-1): Urethane acrylate (product name DA-800AU, NOF Corporation) is used as the thermosetting elastomer resin. The glass transition temperature of the cured product is minus 30°C. Compound (P-1) is obtained by reacting polycaprolactone diol with a number-average molecular weight of 530, isophorone diisocyanate, and 2-hydroxyethyl acrylate. Compound (P-1) has a weight-average molecular weight of 5,200.

[0072] Compound (P-2): Dipentaerythritol hexaacrylate (trade name KAYARAD DPHA, Nippon Kayaku Co., Ltd.) is used as the thermosetting resin. The glass transition temperature of the cured product exceeds 250°C.

[0073] (M) component: powdered magnetostrictive material Fe 49 Co 49 V2 (Epson Atmix Corporation) was used. Average particle size: 8.0±1.0μm.

[0074] (R) component: Radical polymerization initiator 2,2'-Azobis(2-methylpropionate) dimethyl was used as the thermal radical polymerization initiator.

[0075] Example 1 3 parts by mass of the component (R) was added to 100 parts by mass of the compound (P-1) and dissolved by stirring to obtain a homogeneous solution. Next, the component (M) was added so as to have the volume fraction shown in Table 1, and the mixture was stirred to prepare a composition which was a dispersion in which the powdered magnetostrictive material was dispersed. The volume fraction is the (M) component Fe 49 Co 49 The density of V2 is 8.6 g / cm 3 , the density of the compound (P-1) and the component (R) is 1.0 g / cm 3 It was calculated as:

[0076] Examples 2 to 4 Except for changing the volume fraction as shown in Table 1, compositions that were dispersions in which powdered magnetostrictive material was dispersed were prepared in the same manner as in Example 1.

[0077] Example 5 3 parts by mass of the component (R) was added to 100 parts by mass of the compound (P-2) and dissolved by stirring to obtain a homogeneous solution. Next, the component (M) was added so as to have the volume fraction shown in Table 2, and the mixture was stirred to prepare a composition which was a dispersion in which the powdered magnetostrictive material was dispersed. The volume fraction is the (M) component Fe 49 Co 49 The density of V2 is 8.6 g / cm 3 , the density of the compound (P-2) and the component (R) is 1.0 g / cm 3 It was calculated as:

[0078] (Examples 6 to 8) Except for changing the volume fraction as shown in Table 2, compositions that were dispersions in which powdered magnetostrictive material was dispersed were prepared in the same manner as in Example 5.

[0079] <Production of cured sample> Each composition of the examples was poured into a mold of 10 mm x 10 mm x 2 mm. Each mold was then placed on a ceramic hot plate (CHP-170DF (As One)) and subjected to a thermal curing treatment at 80°C for 2 hours under a nitrogen flow, followed by a further thermal curing treatment at 120°C for 1 hour to obtain a cured sample.

[0080] <Evaluation of magnetostriction properties> FIG. 1 is a schematic diagram showing a method for evaluating magnetostriction characteristics in this example. In FIG. 1, a cured sample 20 is placed between a pair of electromagnets 10, 10. An orthogonal strain gauge 30 was attached to a 6 mm square area on the surface of the cured sample 20, and an electromagnet 10 was used to apply a magnetic field ranging from minus 1 tesla to plus 1 tesla in one direction (z-axis direction) horizontally to the surface of the cured sample 20. The direction horizontal to the surface of the cured sample 20 and perpendicular to the z-axis direction was defined as the x-axis direction. The deformation state of the cured sample 20 at this time was evaluated using a vibrating sample magnetometer. The evaluation results are shown in Tables 1 and 2 and Figures 2 to 4, respectively.

[0081] [Table 1]

[0082] [Table 2]

[0083] From the results in Table 1, it was confirmed that, for the cured products obtained by curing the compositions of Examples 1 to 4, which used compound (P-1) as component (P), the cured products obtained by curing the compositions of Examples 1, 2, and 4 exhibited "positive magnetostriction," while only the cured product obtained by curing the composition of Example 3 exhibited "negative magnetostriction." From the results in Table 2, it was confirmed that the cured products obtained by curing the compositions of Examples 5 to 8, which used compound (P-2) as component (P), all exhibited "positive magnetostriction."

[0084] FIG. 2 is a schematic plan view of component (M) particles dispersed in a cured sample before and after application of a magnetic field. In FIG. 2, the arrow (z-axis direction) indicates the direction in which the magnetic field is applied.

[0085] FIG. 2(A) shows the state of (M) component particles 20a dispersed in a cured sample before a magnetic field is applied, which have a substantially circular shape in plan view.

[0086] 2(B) shows the state of the (M) component particles dispersed in the cured sample after the application of a magnetic field. Compared to the state of (M) component particles 21b before the application of the magnetic field, after the application of the magnetic field, (M) component particles 22b elongate in the direction of the applied magnetic field and assume a generally elliptical shape with their major axes parallel to the z-axis in plan view. In other words, a composition in which such (M) component particles are dispersed has positive magnetostriction.

[0087] 2(C) shows the state of the (M) component particles dispersed in the cured sample after the application of a magnetic field. Compared to the state of (M) component particles 23c before the application of the magnetic field, after the application of the magnetic field, (M) component particles 24c have contracted in the direction of the applied magnetic field and have a substantially elliptical shape with the major axis perpendicular to the z-axis in plan view. In other words, a composition in which such (M) component particles are dispersed has negative magnetostriction.

[0088] Figure 3 shows the change in shape of the (M) component particles dispersed in the cured sample of the composition of Example 6 when a magnetic field is applied. The vertical axis represents magnetostriction, λ (ppm), and the horizontal axis represents magnetic flux density, B (mT).

[0089] For the composition of Example 6, the cured sample was confirmed to have positive magnetostriction properties, expanding in the z-axis direction, which is the direction in which the magnetic field is applied, and contracting in the x-axis direction, which is the direction perpendicular to the direction in which the magnetic field is applied, upon application of a magnetic field.

[0090] Figure 4 shows the change in shape of the (M) component particles dispersed in the cured sample of the composition of Example 3 when a magnetic field is applied. The vertical axis represents magnetostriction, λ (ppm), and the horizontal axis represents magnetic flux density, B (mT).

[0091] For the composition of Example 3, negative magnetostriction properties were confirmed, in that the cured sample contracted in the z-axis direction, which is the direction in which the magnetic field was applied, and showed slight expansion and contraction in the x-axis direction, which is the direction perpendicular to the direction in which the magnetic field was applied, when a magnetic field was applied.

[0092] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible within the scope of the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the appended claims. [Explanation of symbols]

[0093] 10 electromagnets, 20 hardened samples, 30 strain gauges

Claims

1. Component (P): a polyfunctional (meth)acrylate compound (excluding those that fall under the category of thermosetting elastomers) as a compound containing a polymerizable group; (M) component: powdered magnetostrictive material; Component (R): an azo-based polymerization initiator as a radical polymerization initiator; A composition having magnetostrictive properties, comprising:

2. 2. The composition according to claim 1, wherein the component (M) is a group of particles made of an iron-based magnetostrictive alloy and having an average particle size of 5 μm or more and 50 μm or less.

3. 3. The composition according to claim 1, wherein the content of the component (M) is 10% by volume or more and 80% by volume or less, based on the total volume of the component (P), the component (M), and the component (R).

4. The composition according to any one of claims 1 to 3, wherein the content of the (R) component is 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the (P) component.

5. The composition according to any one of claims 1 to 4, wherein the component (P) is at least one selected from the group consisting of tri(meth)acrylates, tetra(meth)acrylates, penta(meth)acrylates, and hexa(meth)acrylates.

6. The composition described in claim 5, wherein the glass transition temperature of the cured product of component (P) exceeds 250°C.

7. A cured product obtained by curing the composition according to any one of claims 1 to 6.

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