Resin composition and elastomer material comprising the resin composition

Abstract

To provide a new resin composition which can be suitably used for an elastomer material that has mechanical characteristics such as excellent extensibility and toughness, is excellent in vibration damping properties, and is also excellent in transparency.SOLUTION: An elastomer material is formed of a resin composition containing a polyacrylate resin and silica particles, wherein the polyacrylate resin contains a monomer unit represented by the following general formula (1), the silica particles are 15-50 vol.% with respect to the whole resin composition and have an average particle diameter of less than 150 nm, and a loss coefficient of a non-restricted type composite beam by a central vibration method using a sheet made of the resin composition is 0.04 or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin composition that has excellent mechanical properties such as extensibility and toughness, excellent vibration damping properties, and excellent transparency, and is suitably used as an elastomer material, and an elastomer material comprising the resin composition.

Background Art

[0002] Elastomer materials typified by rubber are widely used as constituent members of numerous products ranging from automobiles, industrial products, and daily necessities due to their excellent flexibility and toughness.

[0003] In particular, in locations where vibration occurs in automobiles, railways, airplanes, home appliances / OA equipment, construction machinery, civil engineering buildings, shoes, sports goods, etc., elastomer materials are used as vibration damping materials that absorb the vibration energy.

[0004] It is known that the vibration damping characteristics of viscoelastic bodies including elastomers are greatly improved by filling with inorganic fillers typified by talc and mica. Since the appearance of composite materials filled with a large amount of inorganic fillers becomes opaque, there has been a demand for highly transparent vibration damping materials.

[0005] For example, Patent Document 1 discloses a vibration damping material containing a polyester resin and 30% by mass or more of mica scales. However, it is aimed at improving the vibration damping property by filling with scaly inorganic fillers, and the transparency of the vibration damping material has been impaired due to the influence of the large amount of filled inorganic fillers.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention solves the above problems, and in particular, has mechanical properties excellent in extensibility and toughness, excellent vibration damping properties, and excellent transparency, and can be suitably used as an elastomer material. An object of the present invention is to provide a resin composition and an elastomer material comprising the resin composition.

Means for Solving the Problems

[0008] The inventors of the present invention have achieved the above object with a resin composition containing a polyacrylate resin and spherical silica particles, wherein the polyacrylate resin contains at least the following general formula (1):

Chemical formula

Effects of the Invention

[0009] The present 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 has excellent vibration damping properties, excellent transparency, and excellent mechanical properties such as extensibility and toughness.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

BEST 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 and spherical silica particles.

[0012] First, the polyacrylate resin contained in the resin composition will be described. The polyacrylate resin needs to contain 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 1.

[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 the acrylate monomer represented by the 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 the silica particles and the physical properties of the resulting resin composition, 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; even more preferably, 2-methoxyethyl acrylate, diethylene glycol monomethyl ether methacrylate. Most preferably, it is diethylene glycol monomethyl ether methacrylate. The acrylate monomer represented by the general formula (1) may be used alone or in combination of two or more kinds as long as the effects of the present invention are not impaired.

[0016] 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, as the bifunctional acrylate monomer, 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 10,000), etc., as the trifunctional acrylate monomer, trimethylolpropane triacrylate, pentaerythritol triacrylate, etc., as the tetrafunctional or higher acrylate monomer, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol octaacrylate, tetra-pentaerythritol decaacrylate, pentapentaerythritol dodecaacrylate, etc. can be mentioned. From the dispersibility of the silica particles and the physical properties of the resulting resin composition, preferably, a bifunctional acrylate monomer, preferably ethylene glycol diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, more preferably diethylene glycol diacrylate. Bifunctional or higher acrylates may be used alone or in combination of multiple types as long as the effects of the present invention are not impaired.

[0017] In the above general formula (1), R 1 When using an acrylate monomer in which is a hydrogen atom, since the resulting acrylate resin has high adhesiveness with a glass transition point far below zero degrees and becomes difficult to handle, it is preferable to use the bifunctional or higher acrylate monomer as a crosslinking agent.

[0018] The bifunctional or higher functional acrylate monomer may be contained in the resin composition in an amount in the range 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 all monomer units. When the bifunctional or higher functional acrylates are 5 mol% or more, the tensile elongation at break of the elastomer material is significantly reduced.

[0019] 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.

Chemical formula

[0020] In formula (2), R 2 represents a hydrogen atom or a methyl group, preferably a methyl group. R 3 represents a methoxy group or an ethoxy group, preferably a methoxy group. R 4 represents a methyl group, a methoxy group or an ethoxy group, preferably a methyl group or a methoxy group.

[0021] Specific examples of the silane coupling agent represented by the general formula (2) include, for example, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like. From the viewpoint of improving mechanical properties, 3-methacryloxypropylmethyldimethoxysilane or 3-methacryloxypropyltrimethoxysilane is preferred, and 3-methacryloxypropyltrimethoxysilane is more preferred. The silane coupling agent represented by the general formula (2) may be used alone or in combination of plural kinds as long as the effects of the present invention are not impaired.

[0022] When the silane coupling agent is used, the resin composition should contain an amount 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.

[0023] 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 )]

[0024] "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, adsorbs, etc. 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, calculate the minimum circular area that can be covered by the 3 O atoms. As a result, the coating area per molecule is 1.3×10 -19 m 2 / molecule. Multiply this by Avogadro's constant 6.0×10 23 molecules / mol to convert it to per mole, and it becomes 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.

[0025] Regarding commercially available silane coupling agents, their characteristic values are indicated and described. In the present invention, the values indicated and described by the supplier may be used.

[0026] Also, the "sum of the surface areas (m 2 ) of the silica particles" is "the surface area (m 2 ) of the silica particles obtained from the average particle diameter" × "the amount of silica particles added (g) ÷ "the density of the silica particles (g / cm 3 )" ÷ "the volume (m 3 ) of the silica particles obtained from the average particle diameter", which is a value obtained by calculation.

[0027] The polyacrylate resin in the resin composition of the present invention may be combined with different acrylate monomers in addition to the acrylate monomer (A) represented by the general formula (1), and may be combined with different silane coupling agents in addition to the silane coupling agent (B) represented by the general formula (2), as long as the effects of the present invention are not impaired.

[0028] Next, the silica particles used in the present invention will be described. In the present invention, the silica particles are important components 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 containing silica particles, it will become a brittle material that cannot withstand large deformations. The shape of the silica particles used in the present invention is not particularly limited as long as the effects of the present invention are not impaired, but it is preferably "spherical" from the viewpoint of transparency. In the present invention, "spherical" means a true sphere, a substantially spherical shape, or an ellipsoid of revolution, excluding rod-shaped and plate-shaped ones, and those with irregularities on the surface are also acceptable. "Spherical silica particles" are silica particles having such a "spherical" shape.

[0029] As such spherical silica particles, known ones, for example, powdered spherical silica particles, colloidal silica (silica sol), etc. can be used. Various known ones having different average particle diameters are known and are also commercially available.

[0030] The silica particles used in the present invention have an average particle diameter of less than 10 μm, 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 even most preferably 150 nm or less. In the present invention, the average particle diameter is represented by the mode diameter measured by a centrifugal sedimentation type particle size distribution measuring device.

[0031] When a substance having a periodic structure like a crystal is irradiated with light of a certain wavelength, in the Bragg condition represented by the relational expression 2dsinθ = nλ (d: the distance between crystal planes, θ: the angle formed by the crystal plane and the light, λ: the wavelength of the light, n: a natural number), due to the relationship between the optical path difference corresponding to the distance between the periodic structures and the incident angle of the light and the wavelength of the light, interference of the scattered light occurs. Spherical silica particles form a colloidal crystal structure in which the particles are periodically arranged at a certain volume fraction or more, and the center-to-center distance between adjacent spherical silica particles becomes d (the distance between crystal planes) in the above relational expression. Since the wavelength at the short wavelength end of visible light is about 380 nm, if the center-to-center distance of the spherical silica particles is shorter than half of this wavelength, the interference of the scattered light will be in a shorter wavelength (ultraviolet region) than the visible light region, so structural coloration by the interference light does not occur. In the resin composition, when adjacent spherical silica particles are in contact with each other, the resin composition behaves as a solid without flexibility. Therefore, in order for the resin composition to exhibit the mechanical properties of an elastomer material, the surface distance between the spherical silica particles needs to be at least 10 to 20 nm or more. That is, in order to make the interference wavelength of the scattered light shorter than the visible light region and avoid coloration by structural coloration and scattering of visible light, it is necessary to make the average particle diameter of the spherical silica particles of the present invention less than 150 nm, whereby a resin composition excellent in transparency can be obtained.

[0032] The content of the silica particles is 9 to 50% by volume, preferably 12 to 48% by volume, more preferably 15 to 45% by volume, even more preferably 18 to 45% by volume, most preferably 34 to 44% by volume, and even most preferably 39 to 41% by volume of the whole resin composition. The less the content of the silica particles, the smaller the reinforcing effect of the polymer material by the filling of the silica particles, and the elastomer material is inferior in tensile breaking stress, tensile breaking strain and loss factor. When the content of the granular silica particles is too large, it becomes difficult to uniformly disperse the silica particles in the acrylate monomer.

[0033] The volume % (V(%)) in the resin composition showing the content of the silica particles in the present invention is the density (d (g / m 3 )) and the weight retention rate (%) obtained from the residual weight (m (g)) after heating at 500 ° C. for 1 hour, and can be obtained according to the following formula. V (%) = [density of resin composition (g / cm 3 )] × [weight retention rate (%) after heating at 500 ° C. for 1 hour] ÷ [density of spherical silica particles (2.2 g / cm 3 )]

[0034] The resin composition of the present invention is obtained by polymerizing at least a dispersion liquid containing an acrylate monomer (A) represented by the general formula (1) and silica particles.

[0035] As the polymerization method, thermal polymerization using a thermal polymerization initiator, photopolymerization involving irradiation with active energy rays such as ultraviolet rays using a photopolymerization initiator, etc. can be used, and other polymerization methods may be used as long as the effects of the present invention are not impaired.

[0036] <Thermal polymerization initiator> As the thermal polymerization initiator, the structure is not particularly limited as long as it generates radicals by heating and initiates the polymerization of the polymerizable functional groups in the resin composition. For example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxy neodecanoate, t-butyl peroxy pivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide, etc. can be mentioned. From the viewpoint of reactivity, 2,2'-azoisobutyronitrile (AIBN) is preferable. The addition amount of the thermal polymerization initiator is 0.001 part by mass or more, preferably 0.01 part by mass or more, more preferably 0.1 part 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, based on 100 parts by weight of the acrylic monomer component. These thermal polymerization initiators may be used alone or in combination of two or more.

[0037] <Photoinitiator> The photoinitiator is not particularly limited as long as it can generate radicals upon ultraviolet irradiation and initiate the polymerization of polymerizable functional groups in the resin composition. As the photoinitiator, it is preferable to use an initiator having light absorption in the wavelength range of 360 nm to 470 nm. For example, acylphosphine oxide-based, α-aminoacetophenone-based, benzophenone-based, camphorquinone-based, and thioxanthone-based initiators can be mentioned. By using these initiators, the polymerization proceeds efficiently to the inside of the resin composition, so that the mechanical strength is improved and the amount of residual components such as the initiator and monomer is reduced.As a photoinitiator, for example, 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), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-[4-(methylthiobenzoyl)]-2-(4-morpholinyl)propane, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one, 1-hydroxycyclohexyl phenyl ketone, [4-[4-methylphenyl]thio]phenyl]phenylmethanone, ethyl 4-(dimethylamino)benzoate, 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]propane-1-one, (methylimino)diethane-2,1-diyl(4-dimethylaminobenzoate), lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate, bis(4-methoxybenzoyl)diethylgermane, etc. can be mentioned. From the viewpoint of reactivity, 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, bis(4-methoxybenzoyl)diethylgermane are preferred, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is more preferred.The addition amount of the photopolymerization initiator 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, based on 100 parts by weight of the acrylic monomer component. These photopolymerization initiators may be used alone or in combination of two or more.

[0038] In addition, in the polymerization reaction, a chain transfer agent may be used. Examples of the chain transfer agent include mercaptocarboxylic acids such as mercaptoacetic acid and 3-mercaptopropionic acid; mercaptoacetic acid methyl, 3-mercaptopropionic acid methyl, 2-ethylhexyl 3-mercaptopropionate, n-octyl 3-mercaptopropionate, methoxybutyl 3-mercaptopropionate, stearyl 3-mercaptopropionate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate) and other mercapto carboxylic acid esters; alkyl mercaptans such as ethyl mercaptan, t-butyl mercaptan, n-dodecyl mercaptan, 1,2-dimercaptoethane; mercapto alcohols such as 2-mercaptoethanol and 4-mercapto-1-butanol; aromatic mercaptans such as benzenethiol, m-toluenethiol, p-toluenethiol, 2-naphthalenethiol; mercapto isocyanurates such as tris[(3-mercaptopropionyloxy)-ethyl] isocyanurate; disulfides such as 2-hydroxyethyl disulfide and tetraethylthiuram disulfide; dithiocarbamates such as benzyldiethyldithiocarbamate; monomer dimers such as α-methylstyrene dimer; and halogenated alkyls such as carbon tetrabromide. The addition amount of the chain transfer agent 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, based on 100 parts by weight of the acrylic monomer component. These may be used alone or in combination of two or more.

[0039] When using powdery silica particles as the silica particles, it is first preferable to disperse the silica particles in the acrylate monomer (A). The method for dispersing the silica particles in the acrylate monomer (A) is not particularly limited as long as the effects of the present invention are not impaired, but a method by ultrasonic treatment is preferable because of its high dispersion effect.

[0040] When using colloidal silica (silica sol) as the silica particles, as the organic solvent, it is preferable to use one that mixes the acrylic monomer component, and examples thereof include alcohols, ketones, esters, and glycol ethers. From 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 can be mentioned. Specifically, colloidal silica (silica sol) dispersed in methanol, isopropyl alcohol, or methyl ethyl ketone is preferable.

[0041] A preferred production method of the resin composition of the present invention is to prepare a dispersion liquid in which a predetermined amount of silica particles are mixed and dispersed in the acrylate monomer (A) represented by the general formula (1), and if necessary, a polymerization initiator, other acrylic monomers, and desired additives are mixed and dispersed in the dispersion liquid, and the obtained dispersion liquid is polymerized. Examples of the desired additives include plasticizers, surfactants, dispersants, antioxidants, ultraviolet absorbers, fluorescent agents, crosslinking agents, organic solvents, etc., and they can be added and used within a range that does not impair the effects of the present invention according to the purpose.

[0042] The resin composition of the present invention can be suitably used as an elastomer material. The elastomer material comprising the resin composition of the present invention is excellent in transparency and vibration damping properties, and is also excellent in mechanical properties such as stretchability and toughness, particularly tensile breaking stress, tensile breaking strain, etc.

[0043] In the present invention, "transparency" refers to transparency to visible light. "Transparency" means that when a 1-mm thick sheet made of the resin composition of the present invention is used, it is placed in a spectrophotometer, and the transmittance of visible light with a wavelength of 480 nm is measured, and at least 70% or more, preferably 73% or more, more preferably 75% or more, and even more preferably 80% or more is transmitted.

[0044] In the present invention, "vibration damping property" means a property evaluated by the loss factor of an unconstrained composite beam obtained by the center excitation method based on JIS-K7391 using a 1-mm thick sheet made of the resin composition of the present invention. More specifically, the loss factor uses the value obtained by the method described in the following examples. The larger the value of the loss factor, the better the vibration damping property. The elastomer made of the composition of the present invention can have a vibration damping property having a loss factor of 0.04 or more, and more preferably 0.05 or more.

[0045] The elastomer material made of the resin composition of the present invention is also excellent in stretchability and toughness, etc., and is excellent in mechanical properties such as tensile breaking stress and tensile breaking strain.

[0046] In the present invention, mechanical properties such as tensile breaking stress and tensile breaking strain mean the tensile breaking stress and tensile breaking strain obtained based on the stress / strain curve obtained in accordance with JIS K7161-2. More specifically, it is described in the following examples.

[0047] The elastomer material made of the resin composition of the present invention has a tensile breaking stress of 4.0 MPa or more, preferably 5 MPa or more, and more preferably 6 MPa or more.

[0048] The elastomer material made of the resin composition of the present invention has a tensile breaking strain of 350% or more, preferably 400% or more, more preferably 500% or more, and even more preferably 600% or more.

Industrial Applicability

[0049] The resin composition of the present invention can be suitably used as a vibration damping elastomeric material, and is formed or processed into films, sheets, display members, interlayer films for glass, coating agents, adhesives, bonding agents, constrained vibration damping sheets, unconstrained vibration damping sheets, etc., and is suitable for use as vibration-proof materials, vibration damping materials, sound absorption and shielding materials adapted to automobiles, railways, airplanes, household appliances and OA equipment, construction machinery, civil buildings, shoes, sports goods, etc.

Examples

[0050] Hereinafter, the present invention will be specifically described with reference to examples. The measurement and evaluation methods for each characteristic value in the examples were carried out as follows. (1) Volume % of spherical silica particles in the resin composition The density (d (g / m 3 )) of the resin composition determined using a dry density meter (AccPyc1330) manufactured by Shimadzu Corporation, and the weight retention rate (%) determined from the residual weight (m (g)) after heating at 500 ° C for 1 hour determined using a differential thermal and thermogravimetric simultaneous measurement device (DTG-60) manufactured by Shimadzu Corporation, the volume % (V (%)) of spherical silica particles was calculated according to the following formula. V (%) = [density of resin composition (g / cm 3 )] × [weight retention rate (%) after heating at 500 ° C for 1 hour] ÷ [density of spherical silica particles (2.2 g / cm 3 )]

[0051] (2) Mechanical properties According to JIS K7161-2, a stress / strain curve was obtained, and the tensile fracture stress and tensile fracture strain were measured.

[0052] For the tensile test, a No. 7 dumbbell test piece (JISK7161-2) was prepared from a 1 mm thick resin composition sheet using a punching die. Using a tensile testing machine (EZ-LX) manufactured by Shimadzu Corporation, it was carried out at a tensile speed of 0.1 mm / min up to a strain of 0.3% under standard environment (temperature 23 ± 2 ° C, in air, humidity (50 ± 10%)), and at a tensile speed of 50 mm / min after a strain of 0.3%.

[0053] (2-1) Tensile fracture stress The tensile fracture stress was evaluated according to the following criteria. 〇: 4.0 MPa ≤ Tensile fracture stress ×: Tensile fracture stress < 4.0 MPa

[0054] (2-2) Tensile fracture strain The tensile fracture strain was evaluated according to the following criteria. 〇: 400% ≤ Tensile fracture strain ×: Tensile fracture strain < 400%

[0055] (3) Transparency (Parallel light transmittance at 480 nm) A sheet of the resin composition with a thickness of 1 mm was subjected to an ultraviolet-visible-infrared spectrophotometer V-670 (manufactured by JASCO Corporation), and the parallel light transmittance at a wavelength of 480 nm corresponding to blue visible light was measured and evaluated according to the following criteria. 〇: Parallel light transmittance at 480 nm ≥ 70% ×: 70% > Parallel light transmittance at 480 nm

[0056] (4) Loss factor A sheet of the resin composition with a thickness of about 1 mm was cut into a size of 10 mm × 250 mm to make a test piece, and it was adhered onto a substrate (SPCC material) with a thickness of 1 mm using an adhesive (manufactured by Toagosei Co., Ltd., trade name: Aron Alpha (registered trademark) jelly-like) to produce an unconstrained composite beam. For the obtained unconstrained composite beam, using a loss factor measuring device (manufactured by Bruel & Kjaer), the loss factor of the unconstrained composite beam at the anti-resonance points of the 2nd to 7th order in the frequency range of 1 to 6 kHz was measured by the center excitation method (JIS K7391) under the condition that the measurement temperature range was -20 to 40°C. The vibration damping performance was evaluated by comparing the maximum value of the loss factor obtained in the above measurement temperature range. Note that the higher the loss factor, the higher the vibration damping performance. 〇: Loss factor ≥ 0.04 ×: 0.04 > Loss factor

[0057] Example 1 2,712 parts by mass of diethylene glycol monomethyl ether methacrylate (MEO2MA, manufactured by Aldrich) and 3,288 parts by mass of spherical silica particles with an average particle diameter of 110 nm (Silbol 110, manufactured by Fuji Chemical Co., Ltd.) were charged into a test tube and dispersed at 5 °C for 10 minutes using an ultrasonic homogenizer (UP200St, manufactured by Hielscher). Next, 3.55 parts by mass of 2,2'-azobisisobutyronitrile (manufactured by Kanto Chemical Co., Inc.) was added as a polymerization initiator and mixed. Thereafter, the obtained dispersion was injected into a mold with a thickness of 1 mm sandwiched between two glass plates with an FEP (copolymer of tetrafluoroethylene and hexafluoropropylene) sheet attached, and heated in an oven at 70 °C for 15 hours to obtain a sheet with a thickness of 1 mm.

[0058] A tensile test was performed using a sheet with a thickness of 1 mm. The obtained stress / strain curve is shown in Figure 1.

[0059] The parallel light transmittance was measured using a sheet with a thickness of 1 mm. The obtained transmittance spectrum is shown in Figure 4.

[0060] In addition, the mechanical properties (tensile fracture stress, tensile fracture strain), transparency, and loss factor measurement results and evaluation results obtained from the stress / strain curve are summarized in Table 1.

[0061] Comparative Examples 1 to 3 Sheets were prepared and evaluated in the same manner as in Example 1, except that the filling amount of silica particles was changed to that shown in Table 1.

[0062] The stress / strain curves obtained using the sheets obtained in Comparative Examples 1 and 2 are shown in Figures 2 and 3, and the transmittance spectra are shown in Figures 5 and 6. The results were shown in Table 1 in the same manner as in Example 1.

[0063]

Table 1

[0064] As is clear from Table 1, the resin composition obtained in Example 1 had excellent mechanical properties with high toughness, having a large tensile breaking stress and tensile breaking strain, and was also excellent in transparency. Further, the loss factor was 0.04 or more, indicating extremely excellent vibration damping properties.

[0065] On the other hand, since the resin composition of Comparative Example 1 did not contain silica particles, it was a brittle material with a small tensile breaking stress and tensile breaking strain. Further, the loss factor was 0.01, and it was inferior in vibration damping properties.

[0066] The resin composition of Comparative Example 2 had a small filling amount of silica particles, both the tensile breaking stress and the tensile breaking strain were low, the reinforcing effect due to the filling of silica particles was small, and it was also inferior in transparency. Since it was inferior in transparency, the loss factor was not measured.

[0067] In Comparative Example 3, when dispersing silica particles in the acrylate monomer (A), the dispersion became highly viscous and difficult to disperse, so that a resin composition could not be obtained.

Claims

1. A resin composition containing a polyacrylate resin and silica particles, wherein the polyacrylate resin contains, at least, the acrylate monomer (A) represented by the following general formula (1): [Chemical Formula 1] [In formula (1), R ０ represents a hydrogen atom, a methyl group or an ethyl group; R １ represents a hydrogen atom or a methyl group; n represents an integer of 1 to 5.], and contains the acrylate monomer (A) as a monomer unit, the content of the silica particles determined using a 1 mm thick sheet made of the resin composition is 15 to 50% by volume of the entire resin composition, the average particle diameter of the silica particles is less than 150 nm, using a 1 mm thick sheet made of the resin composition, the loss factor of the unconstrained composite beam determined by the center excitation method based on JIS-K7391 shows 0.04 or more, when the transmittance of visible light with a wavelength of 480 nm is measured using a 1 mm thick sheet made of the resin composition, the transmittance is at least 70% or more. The resin composition is characterized by the above.

2. when the transmittance of visible light with a wavelength of 480 nm is measured using a 1 mm thick sheet made of the resin composition, the transmittance is at least 80% or more, The resin composition according to claim 1, characterized by the above.

3. The resin composition according to claim 1 or claim 2, wherein the content of the silica particles is 20 to 48% by volume of the entire resin composition.

4. R ０ is a methyl group. The resin composition according to any one of claims 1 to 3.

5. An elastomer material made of a resin composition containing a polyacrylate resin and silica particles, wherein the polyacrylate resin contains, at least, The following general formula (1): [Chemical formula 2] [In formula (1), R ０ represents a hydrogen atom, a methyl group or an ethyl group; R １ represents a hydrogen atom or a methyl group; n represents an integer of 1 to 5.], and contains an acrylate monomer (A) represented by the following formula as a monomer unit, the content of the silica particles determined using a 1 mm thick sheet made of the resin composition is 15 to 50% by volume of the entire resin composition, the average particle diameter of the silica particles is less than 150 nm, using a 1 mm thick sheet made of the above resin composition, when the transmittance of visible light with a wavelength of 480 nm is measured, it is at least 70% or more, and the loss factor of the unconstrained composite beam determined by the central excitation method based on JIS-K7391 is 0.04 or more, characterized in that, the above elastomer material.

6. when the transmittance of visible light with a wavelength of 480 nm is measured using a 1 mm thick sheet made of the resin composition, the transmittance is at least 80% or more, characterized in that, the elastomer material according to claim 5.

7. the content of the silica particles is 20 to 48% by volume of the entire resin composition, the elastomer material according to claim 5 or claim 6.

8. R ０ is a methyl group, the elastomer material according to any one of claims 5 to 7.

9. having at least 4.0 MPa as the tensile breaking stress, the elastomer material according to any one of claims 5 to 8.

10. showing at least 350% as the tensile breaking strain, the elastomer material according to any one of claims 5 to 9.

Images