Resin composition and elastomer material made from the resin composition

Abstract

The present invention provides a resin composition which can be used suitably as an elastomer material that has excellent mechanical properties with respect to stretchability and toughness and also has excellent dielectric properties with respect to a sufficiently larger dielectric constant, a sufficiently smaller dielectric tangent and the like. The present invention relates to a resin composition comprising a polyacrylate resin, silica particles and multilayer graphene, in which the content of the silica particles is 8 to 62% by weight, the content of the multilayer graphene is 1 to 8% by weight and the total content of the silica particles and the multilayer graphene is 15 to 62% by weight each relative to the total amount of the polyacrylate resin, the silica particles and the multilayer graphene.

Description

[Technical Field]

[0001] The present invention relates to a resin composition that has excellent mechanical properties such as tensile strength and toughness, and can be suitably used as an elastomer material exhibiting excellent dielectric properties such as a high dielectric constant, and to an elastomer material made from the resin composition. [Background technology]

[0002] In recent years, with the widespread use of patch antennas in smartphones and RFID systems, lens antennas for millimeter-wave radar, and the advancement of wearable devices utilizing these antenna technologies, there is a growing demand for further miniaturization of communication devices. The size of a communication device can be further reduced by increasing the relative permittivity of the antenna substrate incorporated inside the device. Relative permittivity indicates the degree of polarization within a dielectric material. The higher the relative permittivity of the antenna substrate, the shorter the wavelength of the signal propagating through the circuit formed on the substrate, and the higher the frequency of the signal. In other words, by using a substrate with a high relative permittivity, it is possible to reduce the size of the circuit by increasing the frequency and thus miniaturize the communication device.

[0003] High-dielectric ceramic substrates are known as substrates with high dielectric constants. However, ceramics are very difficult to process, making them unsuitable for antennas with complex shapes.

[0004] Elastomer materials, such as rubber, are widely used as components in a wide range of products, from automobiles and industrial goods to everyday consumer products, due to their processability, excellent flexibility and toughness, which allow them to conform to complex shapes and withstand large deformations.

[0005] For example, Patent Document 1 discloses a highly dielectric elastomer composition obtained by blending highly dielectric ceramic powder with an elastomer. However, it is necessary to blend the highly dielectric ceramic powder in a weight ratio of four times or more relative to the elastomer, and since the majority of the components of the highly dielectric elastomer composition are inorganic, it is difficult to utilize the excellent mechanical properties, including flexibility, that the elastomer possesses. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-187551 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the above-mentioned problems and, in particular, to provide a resin composition and an elastomer material made from the resin composition that can be suitably used as an elastomer material having excellent mechanical properties such as tensile strength and toughness, and exhibiting excellent dielectric properties such as a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent. [Means for solving the problem]

[0008] The present inventors have found a resin composition containing a polyacrylate resin, silica particles, and multilayer graphene, wherein the total amount of the polyacrylate resin, silica particles, and multilayer graphene is such that The silica particle content is 8 to 62% by weight, The content of the multilayer graphene is 1 to 8% by weight. The total content of the silica particles and the multilayer graphene is 15 to 62% by weight. We have arrived at the present invention by discovering that this can be achieved with the above-mentioned resin composition, characterized by the above features. [Effects of the Invention]

[0009] This invention provides a novel resin composition. The resin composition of the present invention is particularly suitable as an elastomer material. The elastomer material comprising the resin composition of the present invention exhibits excellent dielectric properties such as a high relative permittivity and a low rate of change in dielectric loss tangent, as well as excellent mechanical properties such as tensile strength and toughness.

Brief Description of the Drawings

[0010] [Figure 1] Stress-strain curve of the resin composition obtained in Example 1. [Figure 2] Stress-strain curve of the resin composition obtained in Example 2. [Figure 3] Stress-strain curve of the resin composition obtained in Example 3. [Figure 4] Stress-strain curve of the resin composition obtained in Example 4. [Figure 5] Stress-strain curve of the resin composition obtained in Example 5. [Figure 6] Stress-strain curve of the resin composition obtained in Comparative Example 1. [Figure 7] Stress-strain curve of the resin composition obtained in Comparative Example 2. [Figure 8] Stress-strain curve of the resin composition obtained in Comparative Example 3. [Figure 9] Stress-strain curve of the resin composition obtained in Comparative Example 4. [Figure 10] Stress-strain curve of the resin composition obtained in Comparative Example 5. [Figure 11] Stress-strain curve of the resin composition obtained in Comparative Example 6. [Figure 12] Stress-strain curve of the resin composition obtained in Comparative Example 7.

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail. The resin composition of the present invention contains at least a polyacrylate resin, silica particles, and multilayer graphene.

[0012] First, the polyacrylate resin contained in the resin composition will be described. From the viewpoint of further improving mechanical properties and dielectric properties, the polyacrylate resin preferably contains an acrylate monomer (A) represented by the following general formula (1) as a monomer unit. [Chemical formula]

[0013] In formula (1), R 0 represents a hydrogen atom, a methyl group or an ethyl group, preferably a hydrogen atom or a methyl group, more preferably a methyl group. R 1 represents a hydrogen atom or a methyl group, preferably a methyl group. n represents an integer of 1 to 9, preferably 1 to 5, more preferably 1 to 3, even more preferably 1 to 2, and most preferably 2.

[0014] The acrylate monomer (A) represented by the above general formula (1) can be made into an acrylate resin by thermal polymerization or photopolymerization.

[0015] Specific examples of acrylate monomers represented by general formula (1) include, for example, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, diethylene glycol monomethyl ether acrylate, diethylene glycol monomethyl ether methacrylate, triethylene glycol monomethyl ether acrylate, triethylene glycol monomethyl ether methacrylate, polyethylene glycol monomethyl ether methacrylate (number average molecular weight 300), and polyethylene glycol monomethyl ether methacrylate (number average molecular weight 1100). From the viewpoint of the dispersibility of silica particles and the physical properties of the resulting resin composition (particularly from the viewpoint of further improvement of mechanical and dielectric properties), preferably, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, diethylene glycol monomethyl ether acrylate, diethylene glycol monomethyl ether methacrylate, triethylene glycol monomethyl ether acrylate, triethylene glycol monomethyl ether methacrylate, more preferably, 2-methoxyethyl acrylate, diethylene glycol monomethyl ether acrylate, diethylene glycol monomethyl ether methacrylate, triethylene glycol monomethyl ether methacrylate, and even more preferably, 2-methoxyethyl acrylate and diethylene glycol monomethyl ether methacrylate. Most preferably, diethylene glycol monomethyl ether methacrylate. The acrylate monomer represented by general formula (1) may be used alone or in combination of multiple types, as long as the effects of the present invention are not impaired.

[0016] In the polyacrylate resin contained in the resin composition of the present invention, the content of acrylate monomer (A) is not particularly limited, and may be, for example, 1 mol% or more (particularly 10 mol% or more) per 100 mol% of total monomer units. From the viewpoint of further improving mechanical properties and dielectric properties, it is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, sufficiently preferably 99 mol% or more, and most preferably 100 mol%. The content of 100 mol% means that the polyacrylate resin contains acrylate monomer (A) alone as monomer units.

[0017] The polyacrylate resin contained in the resin composition of the present invention may use a bifunctional or higher acrylate monomer as a monomer unit as a crosslinking agent. For example, bifunctional acrylate monomers include ethylene glycol diacrylate, EO-modified bisphenol A diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane diacrylate, polyethylene glycol diacrylate (molecular weight of polyethylene glycol chain 100 to 10000), trifunctional acrylate monomers include trimethylolpropane triacrylate, pentaerythritol triacrylate, and tetrafunctional or higher acrylate monomers include pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol octaacrylate, tetrapentaerythritol decaacrylate, and pentapentaerythritol dodecaacrylate. From the viewpoint of the dispersibility of silica particles and the physical properties of the resulting resin composition (particularly from the viewpoint of further improvement of mechanical and dielectric properties), the preferred material is a difunctional acrylate monomer, more preferably ethylene glycol diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, and even more preferably diethylene glycol diacrylate. Difunctional or higher acrylates may be used alone or in combination, as long as they do not impair the effects of the present invention.

[0018] In the above general formula (1), R 1 When using an acrylate monomer in which hydrogen atoms are present, the resulting acrylate resin becomes highly tacky with a glass transition temperature well below zero degrees Celsius, making it difficult to handle. For this reason, it is preferable to use the aforementioned bifunctional or higher acrylate monomer as a crosslinking agent.

[0019] The aforementioned bifunctional or higher acrylate monomer may be contained in the resin composition in an amount of less than 5 mol%, preferably less than 2 mol%, more preferably less than 1 mol%, and even more preferably less than 0.6 mol%, based on 100 mol% of the total monomer units. If the amount of the bifunctional or higher acrylates is 5 mol% or more, the tensile elongation at break of the elastomer material will decrease significantly.

[0020] The polyacrylate resin contained in the resin composition of the present invention may contain a silane coupling agent represented by the following general formula (2) as a monomer unit. [ka]

[0021] In formula (2), R 2 R represents a hydrogen atom or a methyl group, preferably a methyl group. 3 R represents a methoxy group or an ethoxy group, preferably a methoxy group. 4 This represents a methyl group, a methoxy group, or an ethoxy group, preferably a methyl group or a methoxy group.

[0022] Specific examples of silane coupling agents represented by general formula (2) include, for example, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane. Due to the high degree of improvement in mechanical properties, 3-methacryloxypropylmethyldimethoxysilane or 3-methacryloxypropyltrimethoxysilane is preferred, and 3-methacryloxypropyltrimethoxysilane is more preferred. The silane coupling agents represented by general formula (2) may be used alone or in combination of multiple types, as long as the effects of the present invention are not impaired.

[0023] When the silane coupling agent is used, the amount contained in the resin composition should be such that the surface coating ratio of the silane coupling agent to the silica particles is in the range of 0.005 to 0.080, preferably 0.006 to 0.076, more preferably 0.007 to 0.080, and even more preferably 0.010 to 0.075.

[0024] Here, the surface coating ratio is a value obtained by the following formula. [Surface coating ratio] = [Amount of silane coupling agent contained in the resin composition (g)] × [Minimum coating area of the silane coupling agent (m 2 / g)] ÷ [Sum of the surface areas of the silica particles contained in the resin composition (m 2 )

[0025] The "minimum coating area of the silane coupling agent (m 2 / g)" means the area covered by 1 g of the silane coupling agent on the surface of a material such as silica when it reacts and adsorbs. Usually, the minimum coating area of each silane coupling agent can be calculated as follows. That is, assuming that Si(O)3 obtained by hydrolysis of trialkoxysilane consists of 1 Si atom with a spherical radius of 2.10 Å and 3 O atoms with a spherical radius of 1.52 Å, a Si - O bond distance of 1.51 Å, and a tetrahedral angle of 109.5°, and further assuming that all 3 O atoms in the model react with the silanol groups on the silica surface, the minimum circular area that can be covered by the 3 O atoms is calculated. As a result, the coating area per molecule is 1.3×10 -19 m 2 / molecule. Multiplying this by Avogadro's constant of 6.0×10 23 molecules / mol and converting to per mole gives 7.8×10 4 m 2 / mol. The minimum coating area of each coupling agent refers to the value obtained by dividing the coating area value per mole by the molecular weight of each silane coupling agent.

[0026] For commercially available silane coupling agents, their characteristic values ​​are indicated on the packaging, and in this invention, it is sufficient to use the values ​​indicated by the distributor.

[0027] Also, "Surface area of ​​silica particles (m 2 The sum of the surface areas (m²) of silica particles obtained from the average particle diameter is equal to the sum of the surface areas (m²) of silica particles. 2 )" × "Amount of silica particles added (g) ÷ "Density of silica particles (g / cm³)" 3 )」÷「Volume of silica particles obtained from the average particle size (m³ 3 This is a value obtained by calculating ")".

[0028] In the present invention, polyacrylate resin refers to a resin containing acrylate monomer components as monomer units, such as the compounds represented by formulas (1) and (2) above, and "acrylate monomer component" means a compound containing an acryloyl group or a methacryloyl group. The polyacrylate resin in the resin composition of the present invention may contain, in addition to the acrylate monomer components represented by general formulas (1) and (2), other acrylate monomers, such as alkyl acrylates including n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-nonyl acrylate and isononyl acrylate, as long as the effects of the present invention are not impaired. Isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate Alkyl (meth)acrylates such as acrylate; hydroxyl group-containing acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, polyalkylene glycol (meth)acrylate; trimethylolpropane mono(meth)acrylate, glycerin mono(meth)acrylate, pentae Mono(meth)acrylates of polyols such as lythritol mono(meth)acrylate, ditrimethylolpropane mono(meth)acrylate, and dipentaerythritol mono(meth)acrylate; (meth)acrylates having alicyclic groups such as cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, dicyclopentanyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentanyloxyethyl(meth)acrylate, and dicyclopentenyloxyethyl(meth)acrylate;(meth)acrylates having cyclic ether groups such as glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclohexanespiro-2-(1,3-dioxolan-4-yl)methyl (meth)acrylate, 3-ethyl-3-oxetanylmethyl (meth)acrylate; benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, o-phenylphenoxy (meth)acrylate and Aromatic monofunctional (meth)acrylates such as p-cumylphenolethylene (meth)acrylate; monofunctional (meth)acrylates having a maleimide group such as (meth)acryloryloxyethylhexahydrophthalimide; N-methyl(meth)acrylamide, Nn-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, N-sec-butyl(meth)acrylamide, Nt-butyl(meth)acrylamide, Nn-hexyl(meth)acrylamide, etc. N-hydroxyalkyl(meth)acrylamides such as N-hydroxyethyl(meth)acrylamide; N,N-dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-di-n-propyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di-n-butyl(meth)acrylamide and N,N-dihexyl (Meth)acrylamides such as N,N-dialkyl(meth)acrylamide may be combined, and in addition to the silane coupling agent (B) represented by general formula (2), other silane coupling agents having epoxy groups such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane;Silane coupling agents having an isocyanate group, such as 3-isocyanatetopropylmethyldimethoxysilane, 3-isocyanatetopropyltrimethoxysilane, 3-isocyanatetopropylmethyldiethoxysilane, and 3-isocyanatetopropyltriethoxysilane; and silane coupling agents having an amino group, such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane, may be combined.

[0029] Next, the silica particles used in this invention will be described. In this invention, silica particles are an important component for enabling the resin composition of the present invention to be used as an elastomer material and for improving the toughness of the resin composition. Without silica particles, the material becomes brittle and cannot withstand large deformations. Furthermore, the coexistence of silica particles and multilayer graphene improves the dispersibility of multilayer graphene in the acrylate monomer, making it possible to add more multilayer graphene. In addition, the coexistence of silica particles and multilayer graphene makes it possible to suppress the increase in dielectric loss tangent due to the increase in multilayer graphene.

[0030] The shape of the silica particles used in this invention is not particularly limited as long as it does not impair the effects of the invention, but it is preferable that they be "spherical" from the viewpoint of dispersibility in acrylate monomers (particularly from the viewpoint of further improving mechanical and dielectric properties).

[0031] In this invention, "spherical" refers to a perfect sphere, a nearly spherical shape, or a spheroid, excluding rod-shaped or plate-shaped objects, and may have irregularities on its surface. "Spherical silica particles" are silica particles having such a "spherical" shape.

[0032] Such spherical silica particles can be any known type, such as powdered spherical silica particles or colloidal silica (silica sol). Various known types with different average particle sizes are available and are commercially available.

[0033] The silica particles used in this invention have an average particle diameter of less than 10 μm, and from the viewpoint of further improving mechanical and dielectric properties, are preferably less than 5 μm, more preferably less than 1 μm, even more preferably less than 500 nm, most preferably less than 200 nm, and most preferably 150 nm or less. The average particle diameter of the silica particles may normally be 10 nm or more. In this invention, the average particle diameter is expressed as the mode diameter measured by a centrifugal sedimentation particle size distribution analyzer.

[0034] The silica particle content is typically 8-62% by weight relative to the total amount of polyacrylate resin, silica particles, and multilayer graphene, and is preferably 9-60% by weight, more preferably 10-58% by weight, even more preferably 11-56% by weight, sufficiently preferably 12-54% by weight, even more preferably 15-50% by weight, and most preferably 15-40% by weight, from the viewpoint of further improving mechanical and dielectric properties. The lower the silica particle content, the smaller the reinforcing effect of the polymer material by silica particle filling, resulting in an elastomer material with inferior tensile fracture stress and tensile fracture strain. If the silica particle content is too high, uniform dispersion of the silica particles in the acrylate monomer becomes difficult.

[0035] Next, we will describe the multilayer graphene used in the present invention. The multilayer graphene used in this invention is a plate-like filler in which approximately 2 to 20 graphene particles are stacked on top of each other, with a thickness of several nanometers to tens of nanometers and a width of several micrometers to tens of micrometers. The thickness may be, for example, 1 to 90 nm, and particularly 1 to 20 nm. The width may be, for example, 1 to 80 μm, and particularly 10 to 50 μm. Such multilayer graphene is commercially available and can be obtained, for example, from Fujifilm Wako Pure Chemical Industries, Ltd., Tokyo Chemical Industries Ltd., etc. These can be used as appropriate in this invention.

[0036] The content of the multilayer graphene is typically 1 to 8% by weight relative to the total amount of polyacrylate resin, silica particles, and multilayer graphene. From the viewpoint of further improving mechanical and dielectric properties, it is preferably 1.5 to 8% by weight, more preferably 2 to 8% by weight, even more preferably 2 to 7.5% by weight, sufficiently preferably 2.5 to 7.5% by weight, and even more preferably 3 to 7.5% by weight. The lower the content of multilayer graphene, the smaller the effect of multilayer graphene in increasing the dielectric constant. If the content of multilayer graphene is too high, the viscosity of the dispersion containing the acrylate monomer, silica particles, and multilayer graphene increases, and it loses its fluidity, making processing difficult.

[0037] The resin composition of the present invention is obtained by polymerizing a dispersion containing at least an acrylate monomer (A) represented by general formula (1), silica particles, and multilayer graphene.

[0038] In this process, the total content of silica particles and multilayer graphene is typically 15-62% by weight relative to the total amount of polyacrylate resin, silica particles, and multilayer graphene. From the viewpoint of further improving mechanical and dielectric properties, the content is preferably 15-60% by weight, more preferably 20-59% by weight, even more preferably 24-58% by weight, even more preferably 25-58% by weight, very preferably 25-50% by weight, and most preferably 25-40% by weight. If the amount is too high, the fluidity will be reduced, making it difficult to obtain a sheet. If the amount is too low, the fluidity will be increased, making it difficult to form a sheet. If the total amount is too low, the mechanical properties (especially tensile fracture stress) may decrease.

[0039] The acrylate monomer (A) is typically present in an amount of 38-85% by weight relative to the total amount of polyacrylate resin, silica particles, and multilayer graphene. From the viewpoint of further improving mechanical and dielectric properties, it is preferably used in an amount of 40-85% by weight, more preferably 41-80% by weight, even more preferably 42-76% by weight, even more preferably 42-75% by weight, very preferably 50-75% by weight, and very preferably 60-75% by weight. The content of acrylate monomer (A) may also represent the content of polyacrylate resin in the resulting polyacrylate resin composition.

[0040] Polymerization methods include thermal polymerization using a thermal polymerization initiator, and photopolymerization accompanied by irradiation with active energy rays such as ultraviolet light using a photopolymerization initiator. Other polymerization methods may also be used as long as they do not impair the effects of the present invention.

[0041] <Thermal polymerization initiator> As a thermal polymerization initiator, its structure is not particularly limited as long as it generates radicals upon heating and is used to initiate polymerization of polymerizable functional groups in the resin composition. For example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane1-carbonnitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], Examples of suitable thermal polymerization initiators include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionyl peroxide, and diacetyl peroxide, with 2,2'-azoisobutyronitrile (AIBN) being preferred due to its reactivity. The amount of thermal polymerization initiator added is 0.001 parts by mass or more, preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and also 7 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by weight of the acrylic monomer component. These thermal polymerization initiators may be used alone or in combination of two or more. In this invention, "acrylic monomer component" means a compound containing an acryloyl group and a methacryloyl group, and includes, in addition to the component represented by formula (1) above, other compound components containing acryloyl groups and methacryloyl groups that are used as appropriate.

[0042] <Photopolymerization initiator> The structure of the photopolymerization initiator is not particularly limited as long as it is used to generate radicals upon ultraviolet irradiation and initiate polymerization of polymerizable functional groups in the resin composition. Preferably, the photopolymerization initiator has light absorption at wavelengths of 360 nm to 470 nm. Examples include acylphosphine oxide, α-aminoacetophenone, benzophenone, camphorquinone, and thioxanthone initiators. Using these initiators allows polymerization to proceed efficiently into the resin composition, improving mechanical strength and reducing the amount of residual components such as initiators and monomers.Examples of photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1. ,2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholine-4-ylphenyl)-butan-1-one, 2-[4-(methylthiobenzoyl)]-2-(4-morpholinyl)propane, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, [4-[4-methylphenyl]thio]phenyl]phenylmethanone, 4-(dimethylamino)benzoate ethyl, 1-[4-(2 -Hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 4,4'-bis-(dimethylamino)benzophenone, 4,4'-diethylaminobenzophenone, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-[(4-methylphenyl)sulfonyl]propan-1-one, (methylimino)diethane-2,1-diyl(4-dimethylamibenzoate), lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate, bis(4-methoxybenzo Examples include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate, and bis(4-methoxybenzoyl)diethylgermanium, with 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide being more preferred due to its reactivity.The amount of photopolymerization initiator added is 0.001 parts by mass or more, preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and 7 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by weight of the acrylic monomer component. These photopolymerization initiators may be used individually or in combination of two or more.

[0043] Furthermore, chain transfer agents may be used in the polymerization reaction. Examples of chain transfer agents include mercaptocarboxylic acids such as mercaptoacetic acid and 3-mercaptopropionic acid; mercaptocarboxylic acid esters such as methyl mercaptoacetate, methyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, n-octyl 3-mercaptopropionate, methoxybutyl 3-mercaptopropionate, stearyl 3-mercaptopropionate, trimethylolpropanetris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), and dipentaerythritol hexakis(3-mercaptopropionate); ethyl mercaptan, t-butyl mercaptan, and n-dodecyl methyl mercaptan. Examples include alkyl mercaptans such as lucaptan and 1,2-dimercaptoethane; mercapto alcohols such as 2-mercaptoethanol and 4-mercapto-1-butanol; aromatic mercaptans such as benzenethiol, m-toluenethiol, p-toluenethiol, and 2-naphthalenchiol; mercaptoisocyanurates such as tris[(3-mercaptopropionyloxy)-ethyl]isocyanurate; disulfides such as 2-hydroxyethyl disulfide and tetraethyl thiuram disulfide; dithiocarbamates such as benzyl diethyl dithiocarbamate; monomeric dimers such as α-methylstyrene dimer; and alkyl halides such as carbon tetrabromide. The amount of chain transfer agent added is 0.001 parts by mass or more, preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and 7 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by weight of the acrylic monomer component. These can be used individually or in combination of two or more types.

[0044] When using powdered silica particles, it is preferable to first disperse the silica particles in acrylate monomer (A). The method for dispersing the silica particles in acrylate monomer (A) is not particularly limited as long as it does not impair the effects of the present invention, but ultrasonic treatment is preferred due to its high dispersion effect.

[0045] When colloidal silica (silica sol) is used as silica particles, it is preferable to use an organic solvent that is compatible with the acrylic monomer component, such as alcohols, ketones, esters, and glycol ethers. Due to the ease of solvent removal, alcohol-based organic solvents such as methanol, ethanol, isopropyl alcohol, butyl alcohol, and n-propyl alcohol, and ketone-based organic solvents such as methyl ethyl ketone and methyl isobutyl ketone are preferred. Specifically, colloidal silica (silica sol) dispersed in methanol, isopropyl alcohol, or methyl ethyl ketone is preferred.

[0046] A preferred method for producing the resin composition of the present invention involves preparing a dispersion by mixing and dispersing a predetermined amount of silica particles and multilayer graphene in an acrylate monomer (A) represented by general formula (1), mixing and dispersing a polymerization initiator, other acrylic monomers, and desired additives into the dispersion as needed, and polymerizing the resulting dispersion. Examples of such desired additives include plasticizers, surfactants, dispersants, antioxidants, ultraviolet absorbers, fluorescent agents, crosslinking agents, and organic solvents, and can be added and used as needed, within a range that does not impair the effects of the present invention.

[0047] The content of acrylate monomer (A) in the dispersion may be determined by applying the content of acrylate monomer (A) relative to the "total amount of polyacrylate resin, silica particles, and multilayer graphene" as described above. Note that the acrylate monomer corresponds to the "acrylate monomer component" described above.

[0048] The silica particle content in the dispersion may be determined by applying the silica particle content relative to the "total amount of polyacrylate resin, silica particles, and multilayer graphene" as described above, or by applying it as the silica particle content relative to the "total amount of acrylate monomer, silica particles, and multilayer graphene".

[0049] The content of multilayer graphene in the dispersion may be determined by applying the content of multilayer graphene relative to the "total amount of polyacrylate resin, silica particles, and multilayer graphene" as described above, or by applying it as the content of multilayer graphene relative to the "total amount of acrylate monomer, silica particles, and multilayer graphene".

[0050] The total content of silica particles and multilayer graphene in the dispersion may be calculated by applying the total content of silica particles and multilayer graphene relative to the "total amount of polyacrylate resin, silica particles, and multilayer graphene" as the total content of silica particles and multilayer graphene relative to the "total amount of acrylate monomer, silica particles, and multilayer graphene".

[0051] The resin composition of the present invention can be suitably used as an elastomer material. In this specification, an elastomer material means a polymer material or polymer resin composition that has rubber elasticity such that it undergoes a large change in shape with a relatively small external force and quickly returns to its original shape when the external force is removed, and is a material that can be used as a component material for a member that requires rubber elasticity. The polyacrylate resin contained in the resin composition of the present invention generally exhibits rubber elasticity. The elastomer material comprising the resin composition of the present invention exhibits excellent dielectric properties, particularly high relative permittivity and low rate of change in dielectric loss tangent, as well as excellent mechanical properties such as tensile strength and toughness, and especially tensile fracture stress and tensile fracture strain.

[0052] In the present invention, "relative permittivity" and "dielectric loss tangent" refer to properties evaluated by the relative permittivity and dielectric loss tangent obtained using a 1 mm thick sheet made of the resin composition of the present invention. More specifically, the relative permittivity is the value obtained by the method described in the following examples. A larger relative permittivity indicates a greater degree of polarization within the dielectric. The elastomer made of the composition of the present invention typically has a relative permittivity of 7 or higher, preferably 7.5 or higher, more preferably 7.8 or higher, even more preferably 8.0 or higher, and very preferably 10.0 or higher.

[0053] On the other hand, a smaller dielectric loss tangent indicates that the electrical energy loss within the dielectric material is smaller. The elastomer comprising the composition of the present invention typically has a change rate of the dielectric loss tangent, calculated by the following formula, of 60% or less, preferably 45% or less, more preferably 30% or less, even more preferably 25% or less, very preferably 20% or less, even more preferably 15% or less, and most preferably 10% or less. [Percentage change of dielectric loss tangent] = [[Dielectric loss tangent of resin composition] ÷ [Dielectric loss tangent of polyacrylate resin] - 1] × 100

[0054] The elastomer material comprising the resin composition of the present invention also exhibits excellent extensibility and toughness, as well as excellent mechanical properties such as tensile fracture stress and tensile fracture strain.

[0055] In this invention, mechanical properties such as tensile fracture stress and tensile fracture strain refer to tensile fracture stress and tensile fracture strain obtained based on the stress / strain curve obtained in accordance with JIS K7161-2. More specifically, these are described in the examples below.

[0056] The elastomer material comprising the resin composition of the present invention has a tensile breaking stress of 2.0 MPa or more, preferably 2.3 MPa or more, and more preferably 2.5 MPa or more.

[0057] The elastomer material comprising the resin composition of the present invention has a tensile fracture strain of 350% or more, preferably 400% or more, and more preferably 450% or more.

[0058] The resin composition of the present invention can be suitably used as an elastomer material with a high dielectric constant. The resin composition of the present invention can be molded or processed into films, sheets, coatings, adhesives, etc., and can be suitably used as, for example, the following materials: (i) Materials for antenna substrates applicable to automobiles, railways, aircraft, home appliances / office equipment, construction machinery, wearable devices, etc. (ii) Sealing materials for packages that require miniaturization and thinning, such as optical transceivers; and (iii) Printed circuit board materials.

[0059] For example, when the resin composition of the present invention is used as a sealing material for a package, it can be used in applications such as Wi-Fi modules, optical communication modules, millimeter-wave radar, and electromagnetic shielding. The package may also be an electronic or electrical equipment package. Furthermore, for example, when the resin composition of the present invention is used as a printed circuit board material, it can be applied to smartphones, car navigation systems, power devices, and the like.

[0060] In this specification, mechanical properties are used as a concept that encompasses tensile strength and toughness. Extensibility is the property of exhibiting a sufficiently large tensile fracture strain. The greater the tensile fracture strain, the more desirable the extensibility. Toughness is the property of exhibiting a sufficiently large tensile fracture stress and tensile fracture strain simultaneously. The greater the tensile fracture stress and tensile fracture strain, the more desirable the toughness. Dielectric properties refer to characteristics that exhibit a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent. The value of the dielectric loss tangent varies greatly depending on the monomer composition of the polyacrylate resin. Therefore, it is significant to express the dielectric loss tangent of a given resin composition based on the dielectric loss tangent of a resin composition having a similar composition (for example, simply "polyacrylate resin"), except that it does not contain silica particles and multilayer graphene. Accordingly, in this invention, the dielectric loss tangent of the resin composition is expressed as the rate of change from the dielectric loss tangent of the polyacrylate resin, as described above. Therefore, the lower the dielectric loss tangent of the resin composition, the smaller the rate of change in the dielectric loss tangent of the resin composition. A lower dielectric loss tangent is preferable for the resin composition, and a smaller rate of change in the dielectric loss tangent of the resin composition is also preferable. [Examples]

[0061] The present invention will be specifically described below with reference to examples. The measurement and evaluation methods for each characteristic value in the examples were as follows. (1) Weight % of silica particles and weight % of multilayer graphene in the resin composition The weight percentages of silica particles and multilayer graphene in the resin composition were calculated from the amount of silica particles or multilayer graphene added relative to the total amount of acrylate monomer, silica particles, and multilayer graphene.

[0062] (2) Fluidity of the dispersion before polymerization A dispersion containing silica particles and multilayer graphene dispersed in an acrylate monomer was dropped onto a glass plate tilted at a 60-degree angle, and the fluidity was evaluated from the flow of the droplets after dropping. ◎: The droplets flow, indicating high fluidity. ×: The droplets do not flow, indicating low fluidity.

[0063] (3) Mechanical properties In accordance with JIS K7161-2, stress / strain curves were obtained, and tensile fracture stress and tensile fracture strain were measured.

[0064] For the tensile test, No. 7 dumbbell test specimens (JIS K7161-2) were prepared from a 1 mm thick sheet of resin composition using a punching die. The tensile test was performed using a Shimadzu Corporation EZ-LX tensile testing machine under standard conditions (temperature 23 ± 2°C, air, humidity (50 ± 10%)) at a tensile speed of 0.1 mm / min up to a strain of 0.3%, and at a tensile speed of 50 mm / min thereafter.

[0065] (3-1) Tensile fracture stress The tensile fracture stress was evaluated according to the following criteria. ◎: 2.5 MPa ≤ Tensile fracture stress (Excellent); ○: 2.0 MPa ≤ Tensile fracture stress < 2.5 MPa (Good: No practical problems); ×: Tensile fracture stress < 2.0 MPa (This poses a practical problem).

[0066] (3-2) Tensile fracture strain The tensile fracture strain was evaluated according to the following criteria. ◎: Tensile fracture strain ≤ 450% (Excellent); ○: 350% ≤ tensile fracture strain < 450% (Good: No practical problems); ×: Tensile fracture strain <350% (This poses a practical problem).

[0067] (4) Relative permittivity and dielectric loss tangent A sheet of resin composition with a thickness of approximately 1 mm was used as a test specimen, and the relative permittivity and dielectric loss tangent at 10 MHz were measured at a measurement temperature of 25°C using an impedance analyzer E4991B (manufactured by Keysight Technologies) equipped with a dielectric material test fixture 16453A. The relative permittivity obtained under the above measurement conditions was evaluated according to the following criteria. ◎: Relative permittivity ≥ 10.0 (Excellent); ○: 10.0 > Relative permittivity ≥ 7.0 (Good: No practical problems); ×: 7.0 > Relative permittivity (This presents practical problems).

[0068] (5) Rate of change of dielectric loss tangent Using the dielectric loss tangent value at a frequency of 10 MHz measured above, the rate of change of the dielectric loss tangent was determined according to the following formula. [Percentage change in dielectric loss tangent (%)] = [[Dielectric loss tangent of resin composition] ÷ [Dielectric loss tangent of polyacrylate resin] - 1] × 100 The rate of change in the dielectric loss tangent was evaluated according to the following criteria. ◎: Dielectric loss tangent change rate ≤ 10% (Excellent); ○: 10% < Rate of change in dielectric loss tangent ≤ 25% (good); △: 25% < Rate of change in dielectric loss tangent ≤ 60% (no practical problem) ×: 60% < Rate of change of dielectric loss tangent (problematic in practical applications).

[0069] (6) Overall evaluation The evaluation results for fluidity, tensile fracture stress, tensile fracture strain, relative permittivity, and dielectric loss tangent were comprehensively assessed. Specifically, the lowest evaluation result among these was used as the overall evaluation result.

[0070] Example 1 3386 parts by mass of diethylene glycol monomethyl ether methacrylate (MEO2MA, manufactured by Aldrich), 1056 parts by mass of spherical silica particles with an average particle size of 110 nm (Silbol 110, manufactured by Fuji Chemical Co., Ltd.), and 360 parts by mass of multilayer graphene with a thickness of 6-8 nm and a width of 25 μm (graphene nanoplatelets, manufactured by Tokyo Chemical Co., Ltd.) were placed in a test tube and dispersed in an ultrasonic homogenizer (UP200St, manufactured by Hielscher) at 5°C for 20 minutes. Next, 4.43 parts by mass of 2,2'-azobisisobutyronitrile (manufactured by Kanto Chemical Co., Ltd.) was added as a polymerization initiator and mixed. Subsequently, the resulting dispersion was poured into a 1 mm thick mold sandwiched between two glass plates covered with FEP (a copolymer of tetrafluoroethylene and hexafluoropropylene) sheets, and heated in a 70°C oven for 15 hours to obtain a 1 mm thick sheet.

[0071] Tensile tests were conducted using 1 mm thick sheets. Tensile tests were performed on five test specimens, and the average values ​​are shown in Table 1. In addition, Figure 1 shows the stress / strain curve charts obtained from the five test specimens, with values ​​close to the average.

[0072] Furthermore, Table 1 summarizes the measurement and evaluation results of the fluidity of the dispersion before polymerization, mechanical properties obtained from the stress / strain curve (tensile fracture stress, tensile fracture strain), relative permittivity, dielectric loss tangent, and rate of change of dielectric loss tangent.

[0073] Examples 2-5, Comparative Examples 1-10 The sheets were prepared and evaluated in the same manner as in Example 1, except that the packing amounts of silica particles and multilayer graphene were changed to those shown in Table 1.

[0074] The stress / strain curves obtained using the sheets obtained in Examples 2-5 and Comparative Examples 1-7 are shown in Figures 2-12. The results are shown in Table 1, similar to those in Example 1.

[0075] [Table 1]

[0076] As is clear from Table 1, the resin compositions obtained in Examples 1 to 5 exhibited excellent mechanical properties with high toughness, large tensile fracture stress and tensile fracture strain. Furthermore, the relative permittivity was 7.0 or higher, and the rate of change of the dielectric loss tangent was small or negative in all cases, indicating excellent dielectric properties.

[0077] On the other hand, the resin compositions of Comparative Examples 1 and 2, lacking silica particles, were brittle materials with low tensile fracture stress. Furthermore, they exhibited a large rate of change in dielectric loss tangent, resulting in inferior dielectric properties.

[0078] The resin composition of Comparative Example 3 did not contain silica particles and had a very low content of multilayer graphene, resulting in a brittle material with low tensile fracture stress and tensile fracture strain. Furthermore, it had a low dielectric constant and poor dielectric properties.

[0079] The resin compositions of Comparative Examples 4-6 had a low amount of multilayer graphene filling and were materials with poor dielectric properties, resulting in low relative permittivity values.

[0080] The resin composition of Comparative Example 7 was a brittle material with a low total content of silica particles and multilayer graphene, resulting in low tensile fracture stress.

[0081] In Comparative Examples 8 and 9, when dispersing silica particles and multilayer graphene in acrylate monomer (A), the dispersion became highly viscous, making dispersion difficult, and thus a resin composition could not be obtained. This is thought to be due to an excessive amount of multilayer graphene used for filling.

[0082] In Comparative Example 10, when dispersing silica particles in acrylate monomer (A), the dispersion became highly viscous, making dispersion difficult, and thus a resin composition could not be obtained. This is thought to be due to an excessive amount of silica particles being packed in. [Industrial applicability]

[0083] The resin composition of the present invention is useful for applications such as antenna substrate materials, sealing materials for electronic and electrical equipment packages, and printed circuit board materials.

Claims

1. A resin composition containing a polyacrylate resin, silica particles, and multilayer graphene, wherein, relative to the total amount of the polyacrylate resin, silica particles, and multilayer graphene, The silica particle content is 8 to 62% by weight. The content of the multilayer graphene is 1 to 8% by weight. The resin composition is characterized in that the total content of the silica particles and the multilayer graphene is 15 to 62% by weight.

2. The resin composition according to claim 1, wherein the relative permittivity at a frequency of 10 MHz, determined using a 1 mm thick sheet made of the resin composition, is 7 or more.

3. Using a 1 mm thick sheet made of the aforementioned resin composition, the following formula (1): [Percentage change in dielectric loss tangent (%)] = [[Dielectric loss tangent of resin composition] ÷ [Dielectric loss tangent of polyacrylate resin] - 1] × 100 (1) The resin composition according to claim 1 or 2, wherein the rate of change of the dielectric loss tangent at a frequency of 10 MHz, as determined from the formula, is 60% or less.

4. The resin composition according to claim 3, wherein the rate of change of the dielectric loss tangent is 25% or less.

5. The polyacrylate resin comprises at least the following general formula (1): 【Chemistry 1】 [In formula (1), R ０ R represents a hydrogen atom, a methyl group, or an ethyl group; １ The resin composition according to any one of claims 1 to 4, wherein represents a hydrogen atom or a methyl group; n represents an integer from 1 to 9. ] contains an acrylate monomer (A) as a monomer unit.

6. The resin composition according to any one of claims 1 to 5, wherein the silica particle content is 9 to 60% by weight.

7. R ０ The resin composition according to claim 5, wherein is a methyl group.

8. An elastomer material comprising a resin composition containing polyacrylate resin, silica particles, and multilayer graphene, wherein, with respect to the total amount of polyacrylate resin, silica particles, and multilayer graphene, The silica particle content is 8 to 62% by weight. The content of the multilayer graphene is 1 to 8% by weight. The elastomer material is characterized in that the total content of the silica particles and the multilayer graphene is 15 to 62% by weight.

9. The elastomer material according to claim 8, wherein the relative permittivity at a frequency of 10 MHz, determined using a 1 mm thick sheet made of the resin composition, is 7 or more.

10. Using a 1 mm thick sheet made of the aforementioned resin composition, the following formula (1): [Percentage change in dielectric loss tangent (%)] = [[Dielectric loss tangent of resin composition] ÷ [Dielectric loss tangent of polyacrylate resin] - 1] × 100 (1) The elastomer material according to claim 8 or 9, wherein the rate of change of the dielectric loss tangent at a frequency of 10 MHz, as determined from the formula, is 60% or less.

11. The elastomer material according to claim 10, wherein the rate of change of the dielectric loss tangent is 25% or less.

12. The polyacrylate resin comprises at least, The following general formula (1): 【Chemistry 2】 [In formula (1), R ０ R represents a hydrogen atom, a methyl group, or an ethyl group; １ The elastomer material according to any one of claims 8 to 11, wherein n represents a hydrogen atom or a methyl group; n represents an integer from 1 to 9. The elastomer material contains an acrylate monomer (A) represented by [ ] as a monomer unit.

13. The elastomer material according to any one of claims 8 to 12, wherein the silica particle content is 9 to 60% by weight.

14. R ０ The elastomer material according to claim 12, wherein the group is a methyl group.

15. An elastomer material according to any one of claims 8 to 14, having a tensile fracture stress of at least 2.0 MPa.

16. An elastomer material according to any one of claims 8 to 15, exhibiting a tensile fracture strain of at least 350%.

17. A dispersion containing acrylate monomer, silica particles, and multilayer graphene, wherein, relative to the total amount of acrylate monomer, silica particles, and multilayer graphene, The silica particle content is 8 to 62% by weight. The content of the multilayer graphene is 1 to 8% by weight. The dispersion is characterized in that the total content of the silica particles and the multilayer graphene is 15 to 62% by weight.

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