Curable resin composition

Abstract

Provided is a curable resin composition that has excellent filler dispersibility, excellent vibration-damping properties and transparency, and can be used to form a laminate that does not have self-adhesiveness. The curable resin composition comprises 70 to 40 parts by mass of a (meth)acrylate resin (A) and 30 to 60 parts by mass of a nanofiller (B), and satisfies the following requirements: (1) Visible light (480 nm) transmittance (0.1 mm thickness) is 75% or more. (2) In dynamic viscoelasticity measurements, the loss modulus E" at 25°C is 0.3 MPa or more and the loss tangent tanδ is 0.2 or more.

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition. [Background technology]

[0002] Elastomer materials, such as rubber, are widely used as components in a wide range of products, from automobiles and industrial products to everyday items, due to their excellent flexibility and toughness.

[0003] Elastomer materials are used as vibration-damping materials to absorb vibration energy, particularly in areas where vibration occurs, such as automobiles, trains, aircraft, home appliances, office equipment, construction machinery, civil engineering buildings, shoes, and sporting goods. Damping materials typically consist of laminates in which a dispersion of elastomer material is coated on a substrate and then photopolymerized or thermally polymerized. Therefore, in addition to vibration-damping properties, elastomer materials used in vibration-damping materials must also be sufficiently curable (high curability), resist peeling of the substrate and coating film when laminated (high substrate adhesion), and be non-sticky when laminated (non-self-adhesive).

[0004] It is generally known that vibration-damping properties can be significantly improved by filling elastomer materials with fillers such as talc and mica. However, adding a large amount of filler can result in poor filler dispersibility and an opaque appearance when the dispersion is made. Therefore, elastomer materials used in vibration-damping materials are required to have high dispersion dispersibility and transparency, even when filled with fillers.

[0005] For example, Patent Document 1 discloses a vibration-damping material in which 30% by mass or more of mica flakes are filled into a polyester resin. However, the vibration-damping material in Patent Document 1 has a problem in that it is poor in transparency due to the large amount of scaly inorganic filler that is filled into it.

[0006] Furthermore, Patent Document 2 discloses a vibration-damping material in which spherical nanosilica is filled into an alkoxyethylene oxide group-containing polymethacrylate resin. However, although the vibration-damping material of Patent Document 2 improves vibration-damping properties, it suffers from problems such as being susceptible to oxygen inhibition during photopolymerization, prone to whitening due to silica segregation during thermal polymerization, and low transparency. Another problem is insufficient adhesion to the substrate. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-189854 [Patent Document 2] Japanese Patent Application Publication No. 2022-128119 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention solves the above problems, and aims to provide a curable resin composition that can be used to form a laminate that has excellent filler dispersibility, excellent vibration-damping properties and transparency, and is not self-adhesive. Another object of the present invention is to provide a curable resin composition that has excellent curability. [Means for solving the problem]

[0009] As a result of extensive research to solve these problems, the present inventors have found that the above object can be achieved, and have arrived at the present invention. That is, the gist of the present invention is as follows. <1> A curable resin composition comprising 70 to 40 parts by mass of a (meth)acrylate resin (A) and 30 to 60 parts by mass of a nanofiller (B), which satisfies the following requirements: (1) Visible light (480 nm) transmittance (0.1 mm thickness) is 75% or more (2) In dynamic viscoelasticity measurement, the loss modulus E" at 25°C is 0.3 MPa or more and the loss tangent tanδ is 0.2 or more. <2> The nanofiller (B) is spherical silica or a fibrous filler. <1> The curable resin composition according to claim 1. <3> The (meth)acrylate resin (A) is Contains a monofunctional (meth)acrylate monomer (a) represented by general formula (1) as a monomer unit <1> or <2> The curable resin composition according to claim 1. [ka] [In formula (1), R 1 is a hydrogen atom or a methyl group, R 2 represents a methyl group, an ethyl group, or a phenyl group, and n represents an integer of 1 to 9.] <4> The (meth)acrylate resin (A) contains two or more kinds of (meth)acrylate monomers as monomer units. <1> ~ <3> The curable resin composition according to any one of the preceding claims. <5> The (meth)acrylate resin (A) is A monofunctional (meth)acrylate monomer (a) represented by general formula (1), A monofunctional (meth)acrylate monomer (b) represented by general formula (2), and a polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups as a monomer unit. <1> ~ <4> The curable resin composition according to any one of the preceding claims. [ka] [In formula (2), R 3 is a hydrogen atom or a methyl group, R 4 represents a substituent selected from the group consisting of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. <6> The monofunctional (meth)acrylate monomer (b) is a monofunctional (meth)acrylate monomer having a glass transition temperature of 0°C or higher when polymerized. <5> The curable resin composition according to claim 1. <7> In the (meth)acrylate resin (A), The total content of the monomer units of the monofunctional (meth)acrylate monomer (a) represented by the general formula (1) is 40 to 99 mass %, The total content of the monomer units of the monofunctional (meth)acrylate monomer (b) represented by the general formula (2) is 1 to 60 mass %; The total content of monomer units of polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is more than 0 and less than 5% by mass. <1> ~ <6> The curable resin composition according to any one of the preceding claims. <8> The (meth)acrylate resin (A) is a monofunctional acrylate monomer represented by general formula (3); a monofunctional methacrylate monomer represented by general formula (4); and a polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups as a monomer unit. <1> ~ <7> The curable resin composition according to any one of the preceding claims. [ka] [In formula (3), R 5 represents a methyl group, an ethyl group, or a phenyl group, and n represents an integer of 1 to 9.] [ka] [In formula (4), R 6 represents a methyl group, an ethyl group, or a phenyl group, and n represents an integer of 1 to 9.] <9> In the (meth)acrylate resin (A), The total content of the monomer units of the monofunctional acrylate monomer represented by the general formula (3) is 40 to 99 mass %, The total content of the monomer units of the monofunctional methacrylate monomer represented by the general formula (4) is 1 to 60 mass %; The total content of monomer units of polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is more than 0 and less than 5% by mass. <1> ~ <8> The curable resin composition according to any one of the preceding claims. <10> <1> ~ <9> A dispersion of a curable resin composition containing the raw material monomers of the curable resin composition according to any one of the preceding claims. <11> <10> 1. A laminate obtained by coating a substrate with a dispersion of raw material monomers of the curable resin composition described in 1. above, and then photopolymerizing or thermally polymerizing the coating. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a curable resin composition that has excellent filler dispersibility, excellent vibration-damping properties and transparency, and can be used to form a laminate that does not have self-adhesiveness. Furthermore, according to the present invention, a curable resin composition having excellent curability can also provide curability. The curable resin composition of the present invention can be suitably used as a vibration-damping material. DETAILED DESCRIPTION OF THE INVENTION

[0011] The curable resin composition of the present invention is a poly(meth)acrylate resin (A) filled with a nanofiller (B).

[0012] The poly(meth)acrylate resin (A) used in the curable resin composition of the present invention preferably contains a monofunctional (meth)acrylate monomer (a) represented by general formula (1) as a monomer unit, from the viewpoint of improving the dispersibility of the filler when the resin is made into a dispersion. [ka] In formula (1), R 1 represents a hydrogen atom or a methyl group, preferably a hydrogen atom. 2 represents a methyl group or an ethyl group, preferably a methyl group. n represents an integer of 1 to 9, preferably 1 to 8, more preferably 1 to 5, even more preferably 1 to 3, and most preferably 1.

[0013] Specific examples of the monofunctional (meth)acrylate monomer (a) represented by general formula (1) include 2-methoxyethyl acrylate (MEO), 2-ethoxyethyl acrylate, 2-methoxyethyl methacrylate, diethylene glycol monomethyl ether acrylate, ethoxyethoxyethyl acrylate, diethylene glycol monomethyl ether methacrylate (MEO2MA), triethylene glycol monomethyl ether acrylate, triethylene glycol monomethyl ether methacrylate, polyethylene glycol monomethyl ether methacrylate, and polyethylene glycol monomethyl ether methacrylate. Among these, from the viewpoint of improving the dispersibility of the filler when prepared as a dispersion, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, diethylene glycol monomethyl ether acrylate, ethoxyethoxyethyl acrylate, and triethylene glycol monomethyl ether acrylate are preferred, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, diethylene glycol monomethyl ether acrylate, and ethoxyethoxyethyl acrylate are more preferred, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are even more preferred, and 2-methoxyethyl acrylate and diethylene glycol monomethyl ether methacrylate are most preferred. The (meth)acrylate monomer (a) represented by 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.

[0014] From the viewpoint of improving vibration damping properties when formed into a laminate, the poly(meth)acrylate resin (A) preferably contains, as a monomer unit, a monofunctional (meth)acrylate monomer (b) represented by general formula (2). Among these, from the viewpoint of reducing self-adhesiveness when formed into a laminate, the monofunctional (meth)acrylate monomer (b) is more preferably a monofunctional (meth)acrylate monomer having a glass transition temperature of 0°C or higher, preferably 50°C or higher, when polymerized. [ka] In formula (2), R 3 is a hydrogen atom or a methyl group, R 4 represents a substituent selected from the group consisting of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

[0015] Specific examples of the monofunctional (meth)acrylate monomer (b) represented by general formula (2) include methyl acrylate (MA), methyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate (IBOA), isobornyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, and 4-tert-butylcyclohexyl acrylate. Among these, methyl acrylate and isobornyl acrylate are preferred from the viewpoints of filler dispersibility, vibration damping properties when formed into a laminate, improved transparency, and reduced self-adhesiveness. The monofunctional (meth)acrylate monomer (b) represented by general formula (2) may be used alone or in combination of two or more types, as long as the effects of the present invention are not impaired.

[0016] From the viewpoint of improving curability, the poly(meth)acrylate resin (A) preferably contains, as a crosslinking agent, a polyfunctional (meth)acrylate monomer (c) having two or more polymerizable groups as a monomer unit.

[0017] Specific examples of the polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups include ethylene glycol diacrylate, ethylene glycol dimethacrylate, EO-modified bisphenol A diacrylate, EO-modified bisphenol A dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol diacrylate (HDDA), 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, trimethylolpropane diacrylate, polyethylene glycol diacrylate (polyethylene glycol diacrylate), Examples of suitable (meth)acrylate monomers include difunctional (meth)acrylate monomers (ethylene glycol chain molecular weight: 100 to 10,000), trifunctional (meth)acrylate monomers such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate, tetrafunctional or higher (meth)acrylate monomers such as pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol octaacrylate, tetrapentaerythritol decaacrylate, and pentapentaerythritol dodecaacrylate, and isoprenyl methacrylate (IPEMA). Among these, from the viewpoints of filler dispersibility and vibration damping properties and improved transparency and reduced self-adhesiveness when formed into a laminate, monomers having at least one (meth)acrylic group as a polymerizable group and having a total of two polymerizable groups are preferred, and ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, and isoprenyl methacrylate are more preferred, and 1,6-hexanediol diacrylate and isoprenyl methacrylate are even more preferred.The polyfunctional (meth)acrylate monomer (c) having two or more polymerizable groups may be used alone or in combination of two or more kinds, as long as the effects of the present invention are not impaired.

[0018] In the present invention, the poly(meth)acrylate resin (A) preferably contains two or more (meth)acrylate monomers as monomer units. As a combination of two or more (meth)acrylate monomers, two or more monofunctional (meth)acrylate monomers (a) represented by general formula (1) may be used in combination, or a monofunctional (meth)acrylate monomer (a) represented by general formula (1) may be used in combination with a monofunctional (meth)acrylate monomer (b) represented by general formula (2). Furthermore, these combinations may further include a polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups.

[0019] When two or more monofunctional (meth)acrylate monomers (a) represented by general formula (1) are used in combination, a combination of a monofunctional methacrylate monomer represented by general formula (3) and a monofunctional methacrylate monomer represented by general formula (4) is preferred. Among these, a combination of MEO and MEO2MA is more preferred.

[0020] [ka] In formula (3), R 5 represents a methyl group or an ethyl group, preferably a methyl group. n represents an integer of 1 to 9, preferably 1 to 8, more preferably 1 to 5, even more preferably 1 to 3, and most preferably 1. [ka] In formula (4), R 6 represents a methyl group or an ethyl group, preferably a methyl group. n represents an integer of 1 to 9, preferably 1 to 8, more preferably 1 to 5, even more preferably 1 to 3, and most preferably 1.

[0021] When a monofunctional (meth)acrylate monomer represented by general formula (3) and a monofunctional (meth)acrylate monomer represented by general formula (4) are used in combination, the mass ratio of the monofunctional methacrylate monomer represented by general formula (3) to the monofunctional acrylate monomer represented by general formula (4) is preferably (40 to 99) / (60 to 1), more preferably (40 to 85) / (60 to 15), and even more preferably (60 to 85) / (40 to 15), from the viewpoints of filler dispersibility and vibration damping properties and transparency improvement and self-adhesiveness reduction when formed into a laminate.

[0022] When a monofunctional (meth)acrylate monomer (a) represented by general formula (1) and a monofunctional (meth)acrylate monomer (b) represented by general formula (2) are used in combination, the combinations of MEO and IBOA and MEO and MA are particularly preferred. The mass ratio of the monofunctional (meth)acrylate monomer (a) represented by general formula (1) to the monofunctional (meth)acrylate monomer (b) represented by general formula (2) is preferably (40 to 99) / (60 to 1), more preferably (40 to 85) / (60 to 15), and even more preferably (60 to 85) / (40 to 15), from the viewpoints of filler dispersibility and vibration damping properties and transparency improvement and self-adhesiveness reduction when formed into a laminate.

[0023] The total content of the monofunctional (meth)acrylate monomer (a) represented by general formula (1) in the poly(meth)acrylate resin (A) is preferably 40 to 99% by mass, more preferably 40 to 85% by mass, and even more preferably 60 to 85% by mass. If the total content of the monofunctional (meth)acrylate monomer (a) represented by general formula (1) is less than 40% by mass, not only will the nanofiller (B) be insufficiently dispersed, but vibration-damping properties may be impaired when the resulting laminate is formed. On the other hand, if the content exceeds 99% by mass, the glass transition temperature may be too low, resulting in self-adhesive properties when the resulting laminate is formed.

[0024] In the poly(meth)acrylate resin (A), the total content of the monomer units of the monofunctional (meth)acrylate monomer (b) represented by the general formula (2) is preferably 1 to 60% by mass, more preferably 15 to 60% by mass, and even more preferably 15 to 40% by mass. If the total content of the monomer units of the monofunctional (meth)acrylate monomer (b) represented by the general formula (2) is less than 1% by mass, the glass transition temperature may be too low, and the laminate may exhibit self-adhesiveness. On the other hand, if the content exceeds 60% by mass, not only may the nanofiller (B) be insufficiently dispersed, but the vibration-damping properties may be impaired when the laminate is formed.

[0025] In the poly(meth)acrylate resin (A), the total content of monomer units of the polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is preferably more than 0 and less than 5% by mass, more preferably 0.5 to 3% by mass, and even more preferably 0.5 to 2% by mass. If the content of the polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is 0% by mass, the curability may be insufficient, or the glass transition temperature may be too low when formed into a laminate, resulting in self-adhesiveness. On the other hand, if the content of the polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is 5% by mass or more, the resulting curable resin composition may be brittle.

[0026] The poly(meth)acrylate resin (A) may contain a silane coupling agent (d) represented by the following general formula (5) as a monomer unit.

[0027] [ka] In formula (5), R 7 represents a hydrogen atom or a methyl group, preferably a methyl group. 8 , R 9 R independently represents a methoxy group or an ethoxy group, preferably a methoxy group. 10represents a methyl group, a methoxy group or an ethoxy group, preferably a methyl group or a methoxy group.

[0028] Specific examples of silane coupling agents represented by general formula (5) include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane. Among these, 3-methacryloxypropylmethyldimethoxysilane or 3-methacryloxypropyltrimethoxysilane is preferred, with 3-methacryloxypropyltrimethoxysilane being more preferred, from the viewpoints of filler dispersibility, vibration damping properties when formed into a laminate, improved transparency, and reduced self-adhesiveness. Silane coupling agents represented by general formula (5) may be used alone or in combination of two or more, as long as the effects of the present invention are not impaired.

[0029] The poly(meth)acrylate resin (A) may contain an acrylate monomer other than the monofunctional (meth)acrylate (a) represented by general formula (1), the monofunctional (meth)acrylate (b) represented by general formula (2), and the polyfunctional (meth)acrylate monomer (c) having two or more polymerizable groups, and may contain a silane coupling agent other than the silane coupling agent (d) represented by general formula (5), as long as the effects of the present invention are not impaired.

[0030] The nanofiller (B) used in the curable resin composition of the present invention is an important component for enabling use as a vibration-damping material. Examples of the nanofiller (B) include spherical silica and fibrous fillers. Of these, spherical silica and fibrous alumina are preferred, and spherical silica is even more preferred from the viewpoint of improving transparency when formed into a laminate. If the nanofiller (B) is not contained, the vibration-damping properties of the formed laminate may be inferior. In the present invention, "spherical" refers to a perfect sphere, a nearly spherical sphere, or a spheroid, and excludes rod-like and plate-like shapes. The surface may be uneven. "Fibrous" refers to a shape having a minor axis of 100 nm or less and an average length of 100 to 3,000 nm.

[0031] As the spherical silica, known spherical silica can be used, such as powdered spherical silica, colloidal silica (silica sol), etc. Various known spherical silicas with different average particle sizes are known and commercially available.

[0032] When spherical silica is used as the nanofiller (B), the upper limit of the average particle size of the spherical silica is preferably 150 nm or less, more preferably 140 nm or less, even more preferably 130 nm or less, and even more preferably 120 nm or less, while the lower limit is preferably 10 nm or more, more preferably 50 nm or more. Spherical silica may aggregate, but in this case, the average particle size can be reduced by applying ultrasonic waves. In the present invention, the average particle size refers to the mode diameter measured by a centrifugal sedimentation particle size distribution analyzer.

[0033] When a material with a periodic structure, such as a crystal, is irradiated with light of a certain wavelength, interference of scattered light occurs due to the relationship between the wavelength of light and the optical path difference corresponding to the spacing of the periodic structure and the angle of incidence of the light, as expressed in the Bragg condition, expressed as the relationship 2d sinθ = nλ (d: spacing between crystal planes, θ: angle between the crystal planes and the light, λ: wavelength of light, n: natural number). At a certain volume fraction or above, spherical silica forms a colloidal crystal structure in which particles are periodically arranged, and the center-to-center distance between adjacent spherical silica particles is d (spacing between crystal planes) in the above relationship. Since the wavelength at the shortest wavelength end of visible light is approximately 380 nm, if the center-to-center distance of spherical silica particles is shorter than half of this wavelength, the interference of scattered light will be in the shorter wavelength range (ultraviolet range) than the visible light range, and structural coloring due to interference light will not occur. When adjacent spherical silica particles are in contact with each other in a curable resin composition, the curable resin composition behaves as an inflexible solid. Therefore, in order for the curable resin composition to exhibit the mechanical properties of an elastomer material, the distance between the surfaces of the spherical silica particles must be at least 10 to 20 nm. In other words, to make the interference wavelength of scattered light shorter than the visible light range and to avoid coloration due to structural coloring and scattering of visible light, it is preferable that the spherical silica particles have an average particle size of 150 nm or less. This allows for a curable resin composition with excellent transparency.

[0034] The amount of nanofiller (B) to be filled must be 30 to 60% by mass, preferably 40 to 60% by mass, and more preferably 50 to 60% by mass, based on the total mass of the curable resin composition. If the amount of nanofiller (B) to be filled is less than 30% by mass, the vibration-damping properties of the resulting laminate will decrease, which is undesirable. On the other hand, if the amount of nanofiller (B) to be filled exceeds 60% by mass, the dispersion will become too viscous when dispersing the nanofiller (B), making dispersion impossible, which is undesirable.

[0035] The curable resin composition of the present invention may contain additives, such as plasticizers, surfactants, dispersants, antioxidants, ultraviolet absorbers, fluorescent agents, crosslinking agents, and organic solvents, if necessary.

[0036] In the present invention, a photopolymerization initiator for photopolymerization accompanied by irradiation with active energy rays such as ultraviolet rays, or a thermal polymerization initiator for thermal polymerization can be used. Other polymerization methods may also be used as long as they do not impair the effects of the present invention.

[0037] The photopolymerization initiator is not particularly limited in structure as long as it generates radicals upon irradiation with ultraviolet light and is used to initiate polymerization of polymerizable functional groups in the curable resin composition. As the photopolymerization initiator, it is preferable to use an initiator that has light absorption at a wavelength of 360 to 470 nm, and examples thereof include acylphosphine oxide-based, α-aminoacetophenone-based, benzophenone-based, camphorquinone-based, and thioxanthone-based initiators. By using these initiators, polymerization efficiently progresses to the interior of the curable resin composition, improving mechanical strength and reducing the amount of residual components such as initiators and monomers.

[0038] Specific examples of the photopolymerization initiator 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), 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-propanone) [4-(4-methylphenyl)-benzyl]phenyl}-2-methyl-propan-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]propan-1-one, (methylimino)diethane-2,1-diyl(4-dimethylamibenzoate), lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate, and bis(4-methoxybenzoyl)diethylgermanium. Among these, 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, and bis(4-methoxybenzoyl)diethylgermanium are preferred, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is more preferred.

[0039] The amount of the photopolymerization initiator added is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the poly(meth)acrylate resin (A), while the upper limit is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. The photopolymerization initiators may be used alone or in combination of two or more, as long as they do not impair the effects of the present invention.

[0040] The thermal polymerization initiator is not particularly limited in structure as long as it generates radicals by heating and is used to initiate polymerization of polymerizable functional groups in the curable resin composition. Examples of the thermal polymerization initiator include 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), ... Examples of suitable peroxides include bis(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, and diacetyl peroxide. From the viewpoint of reactivity, 2,2'-azoisobutyronitrile (AIBN) is preferred.

[0041] The amount of the thermal polymerization initiator added is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by weight of the poly(meth)acrylate resin (A), while the upper limit is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. The thermal polymerization initiators may be used alone or in combination of two or more, as long as they do not impair the effects of the present invention.

[0042] 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; mercaptocarboxylic acid esters such as methyl mercaptoacetate, methyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, n-octyl 3-mercaptopropionate, methoxybutyl 3-mercaptopropionate, stearyl 3-mercaptopropionate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), and dipentaerythritol hexakis(3-mercaptopropionate); ethyl mercaptan, t-butyl mercaptan, n-dodecyl mercaptan, and the like. alkyl mercaptans such as 2-mercaptoethanol and 4-mercapto-1-butanol; aromatic mercaptans such as benzenethiol, m-toluenethiol, p-toluenethiol and 2-naphthalenethiol; mercaptoisocyanurates such as tris[(3-mercaptopropionyloxy)-ethyl]isocyanurate; disulfides such as 2-hydroxyethyl disulfide and tetraethylthiuram disulfide; dithiocarbamates such as benzyl diethyldithiocarbamate; monomer dimers such as α-methylstyrene dimer; and alkyl halides such as carbon tetrabromide.

[0043] The amount of the chain transfer agent added is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the poly(meth)acrylate resin (A), while the upper limit is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. The chain transfer agents may be used alone or in combination of two or more, as long as they do not impair the effects of the present invention.

[0044] The curable resin composition of the present invention can be obtained by adding a photopolymerization initiator or a thermal polymerization initiator to a dispersion containing the raw materials, i.e., a monofunctional (meth)acrylate monomer (a) represented by general formula (1) and a nanofiller (B), and, if necessary, a monofunctional (meth)acrylate monomer (b) represented by general formula (2) and a polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups, and mixing them to prepare a dispersion containing the raw material monomers, and curing the dispersion by photopolymerization or thermal polymerization.

[0045] In the present invention, the dispersion liquid is applied to a substrate and photopolymerized or thermally polymerized to form a laminate consisting of the curable resin composition / substrate.

[0046] When spherical silica is used as the nanofiller (B), it is preferable to first disperse the spherical silica in a (meth)acrylate monomer. The method for dispersing the spherical silica in the (meth)acrylate monomer is not particularly limited as long as it does not impair the effects of the present invention, but from the viewpoint of improving dispersibility, a method of treating with an ultrasonic homogenizer is preferred.

[0047] When colloidal silica (silica sol) is used as the spherical silica, it is preferable to use an organic solvent containing the (meth)acrylate monomer component, such as alcohols, ketones, esters, and glycol ethers. From the viewpoint of ease of solvent removal, examples of suitable organic solvents include alcohols such as methanol, ethanol, isopropyl alcohol, butyl alcohol, and n-propyl alcohol, and ketones such as methyl ethyl ketone and methyl isobutyl ketone, and more specifically, methanol, isopropyl alcohol, or methyl ethyl ketone are preferred.

[0048] In the present invention, "dispersibility" means that when a filler is filled, the filler disperses and has transparency and fluidity, and is evaluated by the method described below.

[0049] In the present invention, "curability" means that a laminate is not sticky when formed, and is evaluated by the method described below.

[0050] In the present invention, "transparency" refers to transparency to visible light, and is evaluated by the parallel light transmittance of visible light at a wavelength of 480 nm when a 0.1 mm thick sheet made of the curable resin composition of the present invention is used. The higher the parallel light transmittance, the better the transparency. The transmittance is preferably 75% or more, more preferably 80% or more, and even more preferably 85% or more.

[0051] In the present invention, "vibration damping properties" means attenuating and reducing vibrations, and are evaluated by the loss modulus E" and loss tangent tanδ at 25°C obtained by dynamic viscoelasticity measurement when a 0.1 mm thick sheet made of the curable resin composition of the present invention is used. It is known that the loss modulus E" is proportional to the unconstrained loss factor, and the loss tangent tanδ is proportional to the constrained loss factor. The larger these values ​​are, the better the vibration damping properties are. The loss modulus E" is preferably 0.30 MPa or more, more preferably 0.50 or more, and even more preferably 1.00 or more. The loss tangent tanδ is preferably 0.20 or more, more preferably 0.25 or more, and even more preferably 0.30 or more.

[0052] In the present invention, "self-adhesive" means that when formed into a laminate, it does not have adhesiveness, and is evaluated by the method described below.

[0053] In the present invention, "adhesion to substrate" means that when a laminate is formed, the substrate and the coating film do not peel off from each other, and is evaluated by the method described below.

[0054] The substrate used in the laminate of the present invention is preferably transparent and has a thickness of 0.02 to 1 mm. The material of the substrate is not particularly limited, but examples thereof include polymer substrates such as polyester, polyamide, polyimide, and cycloolefin polymer, and glass substrates.

[0055] The curable resin composition of the present invention can be formed into a laminate that has excellent filler dispersibility, excellent vibration-damping properties, and transparency, and is not self-adhesive, and therefore can be suitably used as a vibration-damping material. It can be molded or processed into films, sheets, display components, glass interlayers, coating agents, pressure-sensitive adhesives, adhesives, constrained vibration-damping sheets, non-constrained vibration-damping sheets, etc., and can be suitably used as vibration-proofing materials, vibration-damping materials, and sound-absorbing and sound-blocking materials that are applicable to automobiles, railways, aircraft, home appliances, office equipment, construction machinery, civil engineering buildings, shoes, sporting goods, etc. [Example]

[0056] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0057] 1.Raw materials A. (Meth)acrylate Monomers MEA: 2-methoxyethyl acrylate, manufactured by Tokyo Chemical Industry Co., Ltd., Tg when polymerized = -50°C MEO2MA: Diethylene glycol monomethyl ether methacrylate, manufactured by Tokyo Chemical Industry Co., Ltd., Tg of polymer = -43°C MA: Methyl acrylate, manufactured by Tokyo Chemical Industry Co., Ltd., Tg when polymerized = 5°C IBOA: Isobornyl acrylate, manufactured by Tokyo Chemical Industry Co., Ltd., Tg of polymer = 97°C HDDA: 1,6-hexanediol diacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. IPEMA: Isoprenyl methacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. B. Nanofiller (B) Spherical silica (110 nm): Spherical silica, Silbol 110 manufactured by Fuji Chemical Co., Ltd., average particle size 110 nm Spherical silica (150 nm): Spherical silica, Silbol 150 manufactured by Fuji Chemical Co., Ltd., average particle size 150 nm Fibrous alumina: Fibrous alumina, Kawaken Fine Chemicals F1000, average diameter 4 nm, average length 1400 nm C. Photopolymerization initiator TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by Tokyo Chemical Industry Co., Ltd.

[0058] 2. Evaluation The physical properties of the curable resin composition were measured by the following methods. (1) Glass transition temperature (Tg) For the sheets obtained in the examples and comparative examples, the glass transition temperature (extrapolated glass transition onset temperature) was determined in accordance with JIS K 7121 using a power compensation differential scanning calorimeter (DSC8000 manufactured by PerkinElmer).

[0059] (2) Dispersibility The dispersions obtained in the examples and comparative examples were evaluated according to the following criteria. ◎: Transparency and fluidity. ×: Transparency was lost (whitening or filler sedimentation, etc.), or fluidity was lost.

[0060] (3) Curability The sheets obtained in the examples and comparative examples were evaluated according to the following criteria. ⊚: Sufficiently hardened and not sticky. ×: Insufficient hardening and stickiness.

[0061] (4) Visible light (480nm) transmittance (0.1mm thickness) A silicone release PET film (PET75xV8 manufactured by Nippa Corp.) was laminated on a glass plate, and 0.15 mm thick shim plates were placed on both ends of the film to take into account the cure shrinkage rate. The dispersion obtained in each of the Examples and Comparative Examples was applied between the shim plates, and a silicone release PET film was laminated on top of the film with the silicone release layer facing downward. A glass plate was then laminated to produce a laminate consisting of glass plate / silicone release PET film / curable resin raw material composition / silicone release PET film / glass plate. The laminate was cured with an ultraviolet curing device (Eye Graphics ECS-4011GX, metal halide lamp M04-L41) at an integrated light dose of 2000 mJ / cm 2 The dispersion was photopolymerized by irradiating it with ultraviolet light, and then the curable resin composition layer was peeled off from the silicone release PET film. The parallel light transmittance of the resulting 0.1 mm thick sheet at a wavelength of 480 nm, which corresponds to blue visible light, was measured using a UV-Visible-Infrared Spectrophotometer V-670 (manufactured by JASCO Corporation), and the transmittance was evaluated according to the following criteria. ◎:Parallel light transmittance≧85%; 〇:85%>Parallel light transmittance≧80%; △:80%>Parallel light transmittance≧75%; ×:75%>Parallel light transmittance

[0062] (5) Loss modulus E" and loss tangent tanδ at 25°C The 0.10 mm thick sheets obtained in the Examples and Comparative Examples were cut into 4 mm × 50 mm test pieces, and the loss modulus E" and loss tangent tanδ were measured using a dynamic viscoelasticity measuring device (TA Instruments, RSA-G2DMA) at a frequency of 5 kHz, a temperature range of -80 to 100°C, and a heating rate of 5°C / min. The loss modulus E" and loss tangent tanδ at 25°C were evaluated according to the following criteria. <Evaluation criteria for loss modulus E"> ◎: 1.00≦E”; ○: 0.50≦E”<1.00; △: 0.30 ≤ E” < 0.50; ×: E”<0.30 <Evaluation criteria for loss tangent tanδ> ◎: 0.30 ≤ tan δ; ○: 0.25≦tanδ<0.30; △: 0.20 ≤ tan δ < 0.25; ×: tanδ<0.20

[0063] (6) Self-adhesiveness and substrate adhesion A PET film (Emplet S-50 manufactured by Unitika Ltd.) was laminated on a glass plate, and 0.15 mm thick shim plates were placed on both ends of the shim plate. The dispersion obtained in the Examples and Comparative Examples was applied between the shim plates, and a silicone release PET film (PET75xV8 manufactured by Nippa Corp.) was laminated on top of that with the silicone release layer facing downward, and a glass plate was then laminated to produce a laminate. The laminate was cured with an ultraviolet curing device (Eye Graphics ECS-4011GX, metal halide lamp M04-L41) at an integrated light dose of 2000 mJ / cm 2 The dispersion was photopolymerized by irradiating it with ultraviolet light of 1000 W at ... The obtained laminate was bent, and the curable resin composition layer was placed on top of it, and whether it could be peeled off was evaluated according to the following criteria. ◎: Peeling was possible; 〇: The sheet was slightly sticky, but could be restored; ×: The adhesiveness was so strong that the sheet was deformed when returned to its original state. Furthermore, 100 grid-like cuts were made in the laminate made of the obtained curable resin composition, and adhesive tape ("Elpack LP-24" manufactured by Nichiban Co., Ltd.) was attached. When the tape was peeled off at a 90-degree angle, the number of grid-like cuts remaining in the curable resin composition layer was evaluated according to the following criteria. ◎:100 pieces 〇:99~90 pieces △:89~50 pieces ×:49~0 pieces

[0064] (7) Overall rating The curable resin composition was comprehensively evaluated based on the results of evaluation of dispersibility, curability, visible light transmittance, loss modulus, loss tangent, self-tackiness, and substrate adhesion. <Evaluation criteria> ◎: All evaluation results were ◎; ○: The lowest evaluation result among all evaluation results was ○; △: The lowest evaluation result among all evaluation results was △; ×: Of all the evaluation results, the lowest evaluation result was ×.

[0065] Example 1 99 parts by mass of 2-methoxyethyl acrylate (MEA), 1 part by mass of 1,6-hexanediol diacrylate (HDDA), and 55 parts by mass of spherical silica with an average particle size of 110 nm (spherical silica (110 nm)) were placed in a container and dispersed using an ultrasonic homogenizer (Hielscher UP200St) at 5°C for 30 minutes. Next, 2.2 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO) was added as a photopolymerization initiator and mixed to prepare a dispersion. A silicone release PET film (PET75xV8 manufactured by Nippa Corp.) was laminated on a glass plate with the silicone release layer facing up, and a 0.15 mm thick shim plate was placed on top of it in consideration of the cure shrinkage rate. The dispersion was applied between the shim plates, and a silicone release PET film (PET75xV8 manufactured by Nippa Corp.) was laminated on top of that with the silicone release layer facing down, and a glass plate was further laminated to produce a laminate consisting of glass plate / silicone release PET film / curable resin composition / silicone release PET film / glass plate. The laminate was cured with an ultraviolet curing device ECS-401GX (manufactured by Eye Graphics Co., Ltd., using a metal halide lamp M04-L41) at an integrated light dose of 2000 mJ / cm 2 The dispersion was photopolymerized by irradiating it with ultraviolet light, and then the glass plate and the silicone release PET film were peeled off to obtain a sheet having a thickness of 0.10 mm.

[0066] Examples 2 to 10, Comparative Examples 1, 2, 4, and 5 As shown in Table 1, the same procedure as in Example 1 was carried out except that the types and amounts of the (meth)acrylate monomer and nanofiller were changed, to obtain a sheet having a thickness of 0.10 mm.

[0067] Comparative Example 3 As shown in Table 1, when an attempt was made to disperse spherical silica in the (meth)acrylate monomer in the same manner as in Example 1, except that the type and amount of the (meth)acrylate monomer and nanofiller were changed, the amount of spherical silica filled was too high, resulting in a high viscosity dispersion and making dispersion difficult. As a result, fluidity was lost and a coating film could not be obtained.

[0068] Table 1 shows the resin composition of the obtained curable resin composition and the property values ​​of the resin composition, dispersion and laminate.

[0069] [Table 1]

[0070] The curable resin compositions obtained in Examples 1 to 10 were excellent in dispersibility and curability, had excellent transparency with a parallel light transmittance of 75% or more, had excellent vibration damping properties with a loss modulus E" of 0.30 MPa or more and a loss tangent tanδ of 0.20 or more at 25°C, and were not self-adhesive and had excellent adhesion to substrates. Comparing Examples 1 to 10, it can be seen that the overall evaluation is excellent or better when the (meth)acrylate resin (A) contains two or more types of (meth)acrylate monomers as monomer units. Furthermore, it can be seen that the overall evaluation is excellent or better when the nanofiller (B) is spherical silica having an average particle size of 140 nm or less, and a monofunctional (meth)acrylate monomer represented by general formula (3) and a monofunctional (meth)acrylate monomer represented by general formula (4) are used in combination at a mass ratio of (40-85) / (60-15), or a monofunctional (meth)acrylate monomer (a) represented by general formula (1) and a monofunctional (meth)acrylate monomer (b) represented by general formula (2) are used in combination at a mass ratio of (40-85) / (60-15).

[0071] The curable resin composition of Comparative Example 1 was not filled with spherical silica, and therefore had poor vibration-damping properties and high self-adhesiveness. The curable resin composition of Comparative Example 2 had poor transparency and vibration-damping properties, and was highly self-adhesive, because the amount of spherical silica filled was too small. The curable resin composition of Comparative Example 3 had too much spherical silica added, so that the composition lost its fluidity and a coating film could not be obtained. The curable resin composition of Comparative Example 4 did not contain a (meth)acrylic monomer having two or more polymerizable groups as a crosslinking agent, and therefore curing after irradiation with ultraviolet light was insufficient and the composition had high self-adhesiveness. The curable resin composition of Comparative Example 5 did not contain a (meth)acrylic monomer having two or more polymerizable groups, which is a crosslinking agent, and therefore had a low tan δ, poor vibration damping properties, and poor adhesion to substrates.

Claims

1. A curable resin composition comprising 70 to 40 parts by mass of a (meth)acrylate resin (A) and 30 to 60 parts by mass of a nanofiller (B), and satisfying the following requirements: (1) Visible light (480 nm) transmittance (0.1 mm thickness) is 75% or more (2) In dynamic viscoelasticity measurement, the loss modulus E" at 25°C is 0.3 MPa or more and the loss tangent tanδ is 0.2 or more.

2. The curable resin composition according to claim 1 , wherein the nanofiller (B) is spherical silica or a fibrous filler.

3. The (meth)acrylate resin (A) is 2. The curable resin composition according to claim 1, which contains a monofunctional (meth)acrylate monomer (a) represented by general formula (1) as a monomer unit. 【Chemistry 1】 [In formula (1), R １ is a hydrogen atom or a methyl group, R ２ represents a methyl group, an ethyl group, or a phenyl group, and n represents an integer of 1 to 9.

4. The curable resin composition according to claim 3 , wherein the (meth)acrylate resin (A) contains two or more kinds of (meth)acrylate monomers as monomer units.

5. The (meth)acrylate resin (A) is A monofunctional (meth)acrylate monomer (a) represented by general formula (1), a monofunctional (meth)acrylate monomer (b) represented by general formula (2); The curable resin composition according to claim 1, which contains, as a monomer unit, a polyfunctional (meth)acrylate monomer (c) having two or more polymerizable groups. 【Chemistry 2】 [In formula (2), R ３ is a hydrogen atom or a methyl group, R ４ represents a substituent selected from the group consisting of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

6. 6. The curable resin composition according to claim 5, wherein the monofunctional (meth)acrylate monomer (b) is a monofunctional (meth)acrylate monomer having a glass transition temperature of 0°C or higher when polymerized.

7. In the (meth)acrylate resin (A), The total content of the monomer units of the monofunctional (meth)acrylate monomer (a) represented by the general formula (1) is 40 to 99 mass%, The total content of the monomer units of the monofunctional (meth)acrylate monomer (b) represented by the general formula (2) is 1 to 60 mass %; The curable resin composition according to claim 1, wherein the total content of monomer units of the polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is more than 0 and less than 5 mass%.

8. The (meth)acrylate resin (A) is a monofunctional acrylate monomer represented by general formula (3); a monofunctional methacrylate monomer represented by general formula (4); The curable resin composition according to claim 1, which contains, as a monomer unit, a polyfunctional (meth)acrylate monomer (c) having two or more polymerizable groups. 【Transformation 3】 [In formula (3), R ５ represents a methyl group, an ethyl group, or a phenyl group, and n represents an integer of 1 to 9. 【Chemistry 4】 [In formula (4), R ６ represents a methyl group, an ethyl group, or a phenyl group, and n represents an integer of 1 to 9.

9. In the (meth)acrylate resin (A), The total content of the monomer units of the monofunctional acrylate monomer represented by the general formula (3) is 40 to 99 mass %, The total content of the monomer units of the monofunctional methacrylate monomer represented by the general formula (4) is 1 to 60 mass %; The curable resin composition according to claim 1, wherein the total content of monomer units of the polyfunctional (meth)acrylate monomer (c) containing two or more polymerizable groups is more than 0 and less than 5 mass%.

10. A dispersion containing raw material monomers for the curable resin composition according to any one of claims 1 to 9.

11. A laminate obtained by applying a dispersion containing raw material monomers of the curable resin composition according to claim 10 to a substrate and then photopolymerizing or thermally polymerizing the dispersion.

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