Epoxy resin modifier, epoxy resin composition containing the same, adhesive made from the epoxy resin composition, and cured resin product obtained by curing the epoxy resin composition.

Abstract

[Problem] To provide: an epoxy resin modifier that is capable of imparting exceptional fracture toughness and peel adhesive strength while maintaining high transparency when blended with an epoxy resin and made into a cured product; an epoxy resin composition containing the epoxy resin modifier; an adhesive and an underfill material composed of the epoxy resin composition; and a cured product obtained by curing the epoxy resin composition. [Solution] This epoxy resin modifier is characterized by containing an A-B-A triblock copolymer having an A block that has a structural unit (a-1) represented by general formula (1) and a structural unit (a-2) derived from a (meth)acrylate having a chain alkyl group, and a B block that has a structural unit (b) derived from a (meth)acrylate having a chain alkyl group or a cyclic alkyl group, the structural unit (a-1) content ranging from 85 mass% to less than l00 mass% per 100 mass% of each A block, and the structural unit (a-2) content ranging from more than 0 mass% to 15 mass% per 100 mass% of each A block. (In general formula (1), R1 is a hydrogen atom or a methyl group. 0≤n≤10, and Q is a four-membered to six-membered cyclic ether group or cyclic thioether group.)

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin modifier, an epoxy resin composition containing the same, an adhesive made from the epoxy resin composition, an underfill material, and a cured resin product obtained by curing the epoxy resin composition. [Background technology]

[0002] Epoxy resin is a general term for thermosetting resins obtained by mixing epoxy resin (main component) containing epoxy groups with amines, acid anhydrides, etc. (curing agents) and performing a heat curing treatment. In addition to its high modulus of elasticity, epoxy resin also has excellent tensile strength, solvent resistance, and electrical properties, and is therefore used in structural adhesives for automobiles, paints for construction and civil engineering, encapsulants (potting materials, underfill materials) for electronic materials such as semiconductors, composite materials for aircraft, composite materials for sporting goods, etc. For example, when a semiconductor circuit is subjected to a heat cycle test, excessive mechanical stress is applied to solder bumps, etc., due to the difference in the coefficient of linear expansion between the circuit board and the semiconductor chip, causing cracks in the solder bumps, etc., and impairing the reliability of the semiconductor circuit connection. To solve this problem, an underfill material made of epoxy resin is filled into the gap between the circuit board and the semiconductor chip.

[0003] However, due to its high modulus of elasticity, epoxy resin also has the characteristic of being prone to the propagation of minute cracks within the resin. As a result, its fracture toughness and peel adhesion are weak, and improvements in these aspects are needed. Therefore, numerous attempts have been made to improve the toughness and peel-and-stick properties of epoxy resins.

[0004] For example, Patent Document 1 discloses that toughness can be improved by blending an epoxy resin with a block copolymer having a block A having structural units derived from (meth)acrylate having a 4-membered to 6-membered ring cyclic ether group or cyclic thioether group, and a block B having structural units derived from (meth)acrylate having a chain alkyl group or cyclic alkyl group.

[0005] Patent Document 2 discloses that toughness (impact resistance) can be improved by incorporating core / shell particles into epoxy resin, in which the main component of the core is polybutadiene or polybutyl acrylate and the main component of the shell is an acrylate or methacrylate polymer.

[0006] Patent Document 3 discloses that toughness and rigidity can be improved by blending an epoxy resin with a block copolymer consisting of a polymer block (a) made of a (meth)acrylic polymer and a polymer block (b) made of an acrylic polymer different from polymer block (a).

[0007] Patent Document 4 discloses that by blending an epoxy resin with a block copolymer having one or more polymer block A mainly composed of structural units derived from alkyl methacrylate and one or more polymer block B mainly composed of structural units derived from alkyl acrylate, fracture toughness and peel adhesion strength can be improved. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2018-35266 [Patent Document 2] Japanese Patent Application Publication No. 9-25393 [Patent Document 3] Re-tabled publication No. 2014-142024 [Patent Document 4] Re-tabled publication No. 2009-101961 [Overview of the project] [Problems that the invention aims to solve]

[0009] In recent years, the performance of structural adhesives for automobiles, electronic materials such as semiconductors, and aerospace materials has been improving. Therefore, higher performance is also required for the epoxy resins used in these applications. However, when sufficiently improving toughness and peel adhesion strength using the above-described method, it is necessary to increase the content ratio of the modifier (block copolymer or core / shell particles) in the epoxy resin. However, an epoxy resin with a large proportion of the modifier has weakened inherent characteristics of the epoxy resin such as tensile strength and solvent resistance, and cannot be applied to materials that require such characteristics. In addition, since the transparency of the resin is also lost, it is impossible to apply it to materials that require transparency.

[0010] An object of the present invention is to provide an epoxy resin modifier that can impart excellent fracture toughness and peel adhesion strength while maintaining high transparency when blended with an epoxy resin and cured, an epoxy resin composition containing the same, an adhesive composed of this epoxy resin composition, an underfill material composed of this epoxy resin, and a cured product obtained by curing this epoxy resin composition.

Means for Solving the Problems

[0011] The epoxy resin modifier of the present invention that has solved the above problems contains a block copolymer, and the block copolymer has a structural unit (a-1) represented by the following general formula (1) and an A block having a structural unit (a-2) derived from a (meth)acrylate having a linear alkyl group, and a B block having a structural unit (b) derived from at least one vinyl monomer selected from the group consisting of a (meth)acrylate having a linear alkyl group and a (meth)acrylate having a cyclic alkyl group, and is an A-B-A type triblock copolymer. The content ratio of the structural unit (a-1) represented by the general formula (1) in each A block is 85% by mass or more and less than 100% by mass in 100% by mass of the A block, and the content ratio of the structural unit (a-2) derived from the (meth)acrylate having a linear alkyl group is more than 0% by mass and 15% by mass or less in 100% by mass of the A block.

[0012] [ka] [In general formula (1), R 1 Q is a hydrogen atom or a methyl group. 0 ≤ n ≤ 10, and Q is a cyclic ether group or cyclic thioether group of 4-membered to 6-membered rings.

[0013] The block copolymer contained in the epoxy resin modifier of the present invention is an ABA-type triblock copolymer having an A block which is a region with high compatibility with epoxy resin and a B block which is a region with low compatibility with epoxy resin.

[0014] The highly compatible Block A contains structural units (a-1) with high affinity to epoxy resin and structural units (a-2) with lower affinity to epoxy resin compared to structural units (a-1). By setting the content of structural units (a-1) with high affinity to epoxy resin to 85% by mass or more and less than 100% by mass in 100% by mass of each Block A, and the content of structural units (a-2) with low affinity to epoxy resin to more than 0% by mass and 15% by mass or less in 100% by mass of each Block A, it is considered that the affinity of Block A to epoxy resin will be appropriate, neither too high nor too low.

[0015] Since block B substantially does not contain structural unit (a-1), it is considered to have lower affinity for epoxy resin and lower compatibility with epoxy resin compared to block A.

[0016] When the epoxy resin modifier of the present invention is blended with epoxy resin, a state is formed in which the low-miscibility B block is dispersed without migrating with the epoxy resin, i.e., a sea-island structure is formed. When cracks propagate in the epoxy resin, these island portions undergo cavitation, and it is believed that the surrounding resin can relax stress using the resulting cavities, thereby dispersing the energy of crack propagation. The extent to which the energy of crack propagation can be dispersed is influenced by the size and shape of the island portions.

[0017] When the epoxy resin modifier of the present invention is blended with epoxy resin, the island portions consisting of Block B become a more uniform nano-sized string-like dispersion state in the epoxy resin, which allows for the most efficient dispersion of crack propagation energy. As a result, the cured epoxy resin composition maintains high transparency while improving fracture toughness and peel adhesion.

[0018] The present invention includes an epoxy resin composition containing an epoxy resin, a curing agent, and the epoxy resin modifier. The present invention also includes an adhesive made from the epoxy resin composition, an underfill material made from the epoxy resin composition, and a cured resin product obtained by curing the epoxy resin composition. [Effects of the Invention]

[0019] According to the present invention, an epoxy resin modifier can be provided that, when compounded with an epoxy resin and cured, maintains high transparency while providing excellent fracture toughness and peel adhesion. The cured epoxy resin composition of the present invention has high transparency and excellent fracture toughness and peel adhesion. [Brief explanation of the drawing]

[0020] [Figure 1] This is a photograph used as a substitute for a diagram, showing the phase separation state of the cured epoxy resin composition No. 2. [Figure 2] This is a photograph used as a substitute for a diagram, showing the phase separation state of the cured product of epoxy resin composition No. 10. [Figure 3] This is a photograph used as a substitute for a diagram, showing the phase separation state of the cured product of epoxy resin composition No. 6. [Modes for carrying out the invention]

[0021] The present invention will be described below based on preferred embodiments, but the present invention is not limited to the following embodiments.

[0022] The epoxy resin modifier of the present invention contains a block copolymer.

[0023] <Block copolymer> The block copolymer contained in the epoxy resin modifier of the present invention is an ABA-type triblock copolymer having a block A having a structural unit (a-1) represented by the general formula (1) described later and a structural unit (a-2) derived from a (meth)acrylate having a chain-like alkyl group, and a block B having a structural unit (b) derived from at least one vinyl monomer selected from the group consisting of (meth)acrylate having a chain-like alkyl group and (meth)acrylate having a cyclic alkyl group. The content of the structural unit (a-1) represented by the general formula (1) in each block A is 85% by mass or more and less than 100% by mass in 100% by mass of block A, and the content of the structural unit (a-2) derived from the (meth)acrylate having a chain-like alkyl group is greater than 0% by mass and 15% by mass or less in 100% by mass of block A.

[0024] The copolymer is preferably a (meth)acrylate-based copolymer. A (meth)acrylate-based copolymer is any copolymer in which structural units derived from (meth)acrylate are the main component (50% by mass or more), and it may contain structural units derived from vinyl monomers other than (meth)acrylate. The content of structural units derived from (meth)acrylate in the copolymer is preferably 80% by mass or more, and more preferably 90% by mass or more, out of 100% by mass of the entire copolymer.

[0025] In the present invention, "Block A" can be replaced with "Segment A," and "Block B" can be replaced with "Segment B." In the present invention, "vinyl monomer" refers to a monomer having a radically polymerizable carbon-carbon double bond in its molecule. "Structural unit derived from vinyl monomer" refers to a structural unit in which the radically polymerizable carbon-carbon double bond of a vinyl monomer polymerizes to become a carbon-carbon single bond. "(meth)acrylic" refers to "at least one of acrylic and methacrylic," and "(meth)acrylate" refers to "at least one of acrylate and methacrylate." Furthermore, (meth)acrylate having a linear alkyl group is (meth)acrylate having an acyclic alkyl group. In the present invention, "(meth)acrylate having a linear alkyl group" can be replaced with "(meth)acrylate acid linear alkyl ester" or "(meth)acrylate acid linear alkyl," and "(meth)acrylate having a cyclic alkyl group" can be replaced with "(meth)acrylate acid cyclic alkyl ester" or "(meth)acrylate acid cyclic alkyl."

[0026] The various components of the aforementioned block copolymer are described below.

[0027] (Block A) Block A is a polymer block having a structural unit (a-1) represented by the following general formula (1) and a structural unit (a-2) derived from a (meth)acrylate having a chain-like alkyl group.

[0028] [ka] [In equation (1), R 1 Q is a hydrogen atom or a methyl group. 0 ≤ n ≤ 10, and Q is a cyclic ether group or cyclic thioether group of 4-membered to 6-membered rings. In equation (1), n ​​is preferably an integer between 0 and 10, more preferably an integer between 0 and 5, and even more preferably an integer between 0 and 3.

[0029] A cyclic ether group or cyclic thioether group represented by Q, having a four- to six-membered ring, is a group having a structure in which at least one carbon atom constituting the ring of a four- to six-membered hydrocarbon is substituted with an oxygen atom or a sulfur atom. As long as the group has a structure in which at least one carbon atom constituting the ring of a four- to six-membered hydrocarbon is substituted with an oxygen atom or a sulfur atom, the carbon atoms constituting the ring may be substituted with other atoms. A specific example of these other atoms is a nitrogen atom. Furthermore, two or more carbon atoms constituting the ring of a four- to six-membered hydrocarbon may be substituted with atoms other than carbon atoms. In addition, the bonds constituting the four- to six-membered ring may be either saturated or unsaturated bonds. Furthermore, in a cyclic ether group or cyclic thioether group represented by Q, hydrogen atoms directly bonded to the ring atoms may be substituted with substituents. Examples of such substituents include hydrocarbon groups. Furthermore, since the group represented by Q has a cyclic ether structure or a cyclic thioether structure and is considered to have high compatibility with epoxy resins, a cyclic acid anhydride group that easily opens its ring is undesirable.

[0030] Specific examples of cyclic ether groups with four to six membered rings represented by Q include, for example, cyclic ether groups in which the carbon atoms constituting the four to six membered rings are substituted with at least one oxygen atom, such as oxetanyl group (4), furanyl group (furyl group, 5), tetrahydrofurfuryl group (6), pyranyl group (7a, 7b), dihydropyranyl group (8a, 8b), tetrahydropyranyl group (9), dioxolanyl group (10), and dioxanyl group (11); and cyclic ether groups in which the carbon atoms constituting the four to six membered rings are substituted with oxygen and nitrogen atoms, such as oxazole Examples of cyclic thioether groups include the 12-4 group, oxazinyl group (13a-13h), and morpholino group (14); the thiethanyl group (15) and thienyl group (16), which are cyclic thioether groups in which carbon atoms constituting a 4-membered to 6-membered ring are substituted with sulfur atoms; the thiazolyl group (17), which is a cyclic thioether group in which carbon atoms constituting a 4-membered to 6-membered ring are substituted with sulfur and nitrogen atoms; and the oxathiolanyl group (18), which is a cyclic ether group (or cyclic thioether group) in which carbon atoms constituting a 4-membered to 6-membered ring are substituted with oxygen and sulfur atoms. The chemical formulas of the above functional groups are shown below. The numbers in parentheses next to the functional group names correspond to the numbers in the chemical formulas.

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] In the chemical formula, the position where the (meth)acrylic acid skeleton bonds to the ring structure of Q is shown as a representative example, but it is not limited to this. That is, the (meth)acrylic acid skeleton can bond to any atom that makes up the ring structure of Q.

[0035] Q is preferably a group that does not have an unsaturated bond, such as an oxetanyl group (4), a tetrahydrofurfuryl group (6), a thietanyl group (15), a tedrahydropyranyl group (9), a dioxolanyl group (10), a dioxanyl group (11), an oxathiolanyl group (18), or a morpholino group (14).

[0036] Specific examples of vinyl monomers that form the structural unit (a-1) represented by general formula (1) include tetrahydrofurfuryl (meth)acrylate, morpholino (meth)acrylate, morpholinoethyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, 1,3-dioxane-(meth)acrylate, and the like.

[0037] Block A may have only one type of structural unit (a-1) represented by general formula (1), or it may have two or more types of structural units (a-1) represented by general formula (1).

[0038] The structural unit (a-1) represented by general formula (1) has a cyclic ether group or a cyclic thioether group that has a high affinity for epoxy resin, thereby improving the compatibility of block A with epoxy resin.

[0039] The content of structural unit (a-1) represented by general formula (1) in each A block is 85% by mass or more, preferably 87% by mass or more, more preferably 88% by mass or more, even more preferably 89% by mass or more, less than 100% by mass, preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less. By setting the content of structural unit (a-1) within the above range, the compatibility of A block with epoxy resin is improved, and B block can be dispersed in the epoxy resin at the nanoscale, resulting in a cured epoxy resin composition that exhibits high transparency.

[0040] The content of the structural unit (a-1) in each A block is the content in the A block at one end of the block copolymer and the A block at the other end, respectively.

[0041] Block A has, in addition to the structural unit (a-1) represented by the general formula (1) described above, a structural unit (a-2) derived from a (meth)acrylate having a chain-like alkyl group. Structural unit (a-2) has a lower affinity for epoxy resin than structural unit (a-1).

[0042] Examples of linear alkyl groups and branched alkyl groups can be found in (meth)acrylates having a linear alkyl group constituting the structural unit (a-2). Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, and n-decyl group. Examples of branched alkyl groups include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, sec-pentyl group, tert-pentyl group, neopentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, 2-ethylhexyl group, isoheptyl group, isooctyl group, isononyl group, and isodecyl group. Among these, linear alkyl groups having 1 to 10 carbon atoms are preferred, linear alkyl groups having 1 to 10 carbon atoms and / or branched alkyl groups having 3 to 10 carbon atoms are more preferred, and branched alkyl groups having 3 to 10 carbon atoms are even more preferred. This is because using (meth)acrylates having such linear alkyl groups allows for good compatibility of block A with epoxy resin while maintaining an appropriate affinity range for block A with epoxy resin.

[0043] Block A may have only one type of structural unit (a-2), or it may have two or more types of structural unit (a-2).

[0044] The content of structural unit (a-2) in each A block is greater than 0% by mass, preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, 15% by mass or less, preferably 13% by mass or less, more preferably 12% by mass or less, and even more preferably 11% by mass or less, by setting the content of structural unit (a-2) within the above range. By setting the content of structural unit (a-2) within the above range, the affinity of A block to epoxy resin is appropriate, and B block can be dispersed in the epoxy resin in a nano-sized string-like dispersion state, so that the cured product of the resulting epoxy resin composition has excellent fracture toughness and peel adhesion.

[0045] The content of the structural unit (a-2) in each A block is the content in the A block at one end of the block copolymer and the A block at the other end, respectively.

[0046] Block A may consist only of the aforementioned structural units (a-1) and (a-2), or it may include other structural units (a-3) to the extent that it maintains an appropriate affinity of Block A to the epoxy resin.

[0047] Other structural units (a-3) that may be included in Block A are not particularly limited as long as they are formed from vinyl monomers that form structural unit (a-1) represented by general formula (1), (meth)acrylates having a chain alkyl group that form structural unit (a-2), and vinyl monomers that can copolymerize with the vinyl monomers that form Block B described later. Specific examples of vinyl monomers that can form other structural units (a-3) in Block A include aromatic vinyl monomers, vinyl monomers having a hydroxyl group, vinyl monomers having a carboxyl group, vinyl monomers having a sulfonic acid group, vinyl monomers having a phosphate group, vinyl monomers containing a tertiary amine, vinyl monomers containing a quaternary ammonium base, vinyl monomers containing a heterocycle, vinyl amides, vinyl monomers containing an epoxy group, vinyl carboxylates, α-olefins, dienes, (meth)acrylic monomers, and the like.

[0048] Examples of aromatic vinyl monomers include styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, and 1-vinylnaphthalene.

[0049] Examples of vinyl monomers having a hydroxyl group include hydroxyalkyl (meth)acrylates.

[0050] Examples of vinyl monomers having a carboxyl group include monomers obtained by reacting a vinyl monomer having a hydroxyl group with an acid anhydride such as maleic anhydride, succinic anhydride, or phthalic anhydride, as well as crotonic acid, maleic acid, itaconic acid, and (meth)acrylic acid.

[0051] Examples of vinyl monomers having a sulfonic acid group include vinyl sulfonic acid, styrene sulfonic acid, ethyl (meth)acrylate disulfonate, methylpropyl sulfonic acid (meth)acrylamide, and ethyl (meth)acrylamide sulfonate.

[0052] Examples of vinyl monomers having a phosphate group include methacryloyloxyethyl phosphate ester.

[0053] Examples of vinyl monomers containing tertiary amines include N,N-dimethylaminopropyl(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylamide, 2-(dimethylamino)ethyl(meth)acrylate, and N,N-dimethylaminopropyl(meth)acrylate.

[0054] Examples of vinyl monomers containing quaternary ammonium bases include N-2-hydroxy-3-acryloyloxypropyl-N,N,N-trimethylammonium chloride and N-methacryloylaminoethyl-N,N,N-dimethylbenzylammonium chloride.

[0055] Examples of vinyl monomers containing heterocycles include 2-vinylthiophene, N-methyl-2-vinylpyrrole, 1-vinyl-2-pyrrolidone, 2-vinylpyridine, and 4-vinylpyridine.

[0056] Examples of vinylamides include N-vinylformamide, N-vinylacetamide, and N-vinyl-ε-caprolactam.

[0057] Examples of vinyl monomers containing epoxy groups include glycidyl (meth)acrylate.

[0058] Examples of vinyl carboxylates include vinyl acetate, vinyl pivalate, and vinyl benzoate. Examples of α-olefins include 1-hexene, 1-octene, and 1-decene. Examples of dienes include butadiene, isoprene, 4-methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene.

[0059] Examples of (meth)acrylic monomers include (meth)acrylates having a cyclic alkyl group, (meth)acrylates having a hydroxyl group, (meth)acrylates having an alkoxy group, (meth)acrylates having a sulfonic acid group, (meth)acrylates containing a tertiary amine, (meth)acrylates containing an epoxy group, (meth)acrylates having polyethylene glycol structural units, (meth)acrylates having an aromatic ring group, and (meth)acrylamide.

[0060] Examples of (meth)acrylates having a cyclic alkyl group include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate.

[0061] Examples of (meth)acrylates having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0062] Examples of (meth)acrylates having an alkoxy group include methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

[0063] Examples of (meth)acrylates having a sulfonic acid group include ethyl disulfonate (meth)acrylate.

[0064] Examples of tertiary amine-containing (meth)acrylates include 2-(dimethylamino)ethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate.

[0065] Examples of (meth)acrylates containing epoxy groups include glycidyl (meth)acrylate.

[0066] Examples of (meth)acrylates having polyethylene glycol structural units include diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate.

[0067] Examples of (meth)acrylates having an aromatic ring group include benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0068] Examples of (meth)acrylamides include (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N,N-dimethyl(meth)acrylamide.

[0069] The vinyl monomers capable of forming structural unit (a-3) may be used individually or in combination of two or more.

[0070] If block A contains structural unit (a-3), the content of structural unit (a-3) in each block A is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, and particularly preferably 5% by mass or less, based on 100% by mass of each block A. The lower limit of the content of structural unit (a-3) is 0% by mass.

[0071] The content of the structural unit (a-3) in each A block is the content in the A block at one end of the block copolymer and the A block at the other end, respectively.

[0072] Furthermore, it is preferable that block A substantially does not contain structural unit (b) present in block B. That is, in block A, the content of structural unit (b) present in block B is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, and particularly preferably 2% by mass or less, based on 100% by mass of each block A. The lower limit of the above content is 0% by mass.

[0073] If block A contains two or more structural units, the various structural units contained in block A may be contained in block A in any manner, such as random copolymerization or block copolymerization, and from the viewpoint of uniformity, it is preferable that they are contained in a manner of random copolymerization. For example, block A may be formed by a copolymer of a block consisting of structural units (a-1) and a block consisting of structural units (a-2).

[0074] (Block B) Block B is a polymer block having structural unit (b) derived from at least one vinyl monomer selected from the group consisting of (meth)acrylates having a chain-like alkyl group and (meth)acrylates having a cyclic alkyl group. Since Block B substantially does not contain structural unit (a-1) derived from the vinyl monomer, it is considered to have lower compatibility with epoxy resins compared to Block A.

[0075] Examples of (meth)acrylates having a chain-like alkyl group include dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate (stearyl (meth)acrylate), and nonadecyl (meth)acrylate. Among these, (meth)acrylates having a chain-like alkyl group with 11 to 20 carbon atoms are preferred. The chain-like alkyl group may be either a linear alkyl group or a branched alkyl group, but a linear alkyl group is preferred.

[0076] Examples of (meth)acrylates having a cyclic alkyl group include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, ethylcyclohexyl (meth)acrylate, butylcyclohexyl (meth)acrylate, pentylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate. Among these, (meth)acrylates having a cyclic alkyl group (particularly monocyclic alkyl group) with 6 to 15 carbon atoms are preferred.

[0077] The vinyl monomer may be used alone or in combination of two or more types.

[0078] As the vinyl monomer forming structural unit (b), it is particularly preferable to use a (meth)acrylate having a chain-like alkyl group, more preferably a (meth)acrylate having a chain-like alkyl group with 11 to 20 carbon atoms, even more preferably a (meth)acrylate having a linear alkyl group with 11 to 20 carbon atoms, and especially preferably a (meth)acrylate having a linear alkyl group with 11 to 15 carbon atoms. This is because using a (meth)acrylate having a chain-like alkyl group with 11 to 20 carbon atoms as the vinyl monomer forming structural unit (b) makes block B more flexible, improves the energy dispersion effect during crack propagation, and results in a cured epoxy resin composition with improved fracture toughness and peel adhesion.

[0079] The content of structural unit (b) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on 100% by mass of the entire B block. The upper limit of the content of structural unit (b) is 100% by mass. By setting the content of structural unit (b) within the above range, a cured epoxy resin composition with improved fracture toughness and peel adhesion can be obtained.

[0080] Block B may consist only of structural unit (b), or it may contain other structural units to the extent that it maintains the low compatibility of Block B with epoxy resin. Furthermore, it is preferable that Block B substantially does not contain structural units (a-1) and (a-2) that Block A possesses. That is, in Block B, the respective content of structural units (a-1) and (a-2) that Block A possesses is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, and particularly preferably 2% by mass or less, based on 100% by mass of Block B. The lower limit of the above content is 0% by mass.

[0081] Specific examples of vinyl monomers that can form other structural units in Block B include aromatic vinyl monomers, vinyl monomers having a hydroxyl group, vinyl monomers having a carboxyl group, vinyl monomers having a sulfonic acid group, vinyl monomers having a phosphate group, vinyl monomers containing a tertiary amine, vinyl monomers containing a quaternary ammonium base, vinyl monomers containing a heterocycle, vinyl amides, vinyl monomers containing an epoxy group, vinyl carboxylates, α-olefins, dienes, (meth)acrylic monomers, and the like.

[0082] Examples of (meth)acrylic monomers include (meth)acrylates having a hydroxyl group, (meth)acrylates having an alkoxy group, (meth)acrylates having a sulfonic acid group, (meth)acrylates containing a tertiary amine, (meth)acrylates containing an epoxy group, (meth)acrylates having polyethylene glycol structural units, (meth)acrylates having aromatic ring groups, and (meth)acrylamides.

[0083] Specific examples of the vinyl monomer mentioned above include those exemplified as specific examples of vinyl monomers that can form other structural units (a-3) of block A.

[0084] The vinyl monomers used in Block B can be of one type or two or more types.

[0085] The content of other structural units in block B is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of the entire block B. The lower limit for the content of other structural units in block B is 0% by mass.

[0086] If block B contains two or more structural units, the various structural units contained in block B may be contained in block B in any manner, such as random copolymerization or block copolymerization, but from the viewpoint of uniformity, it is preferable that they be contained in the manner of random copolymerization.

[0087] (Block copolymer) The block copolymer contained in the epoxy resin modifier of the present invention is an ABA-type triblock copolymer (where A represents "block A" and B represents "block B"). By using an ABA-type triblock copolymer, the B blocks can be dispersed in the epoxy resin in a more uniform string-like manner, thereby achieving high peel adhesion and fracture toughness.

[0088] In block A, the types and amounts of each constituent unit in block A at one end may be the same as, or different from, the types and amounts of each constituent unit in block A at the other end.

[0089] In an ABA-type triblock copolymer, if the content of structural unit (a-1) differs between the A block at one end and the A block at the other end, the block with a higher content of structural unit (a-1) is designated as block A1, and the block with a lower content of structural unit (a-1) is designated as block A2.

[0090] The mass ratio of block A1 to block A2 (block A1 / block A2) is not particularly limited, but is preferably 0.8 or higher, more preferably 0.85 or higher, preferably 1.2 or lower, more preferably 1.15 or lower, and even more preferably 1.1 or lower. By adjusting the mass ratio of block A1 to block A2 (block A1 / block A2) within the above range, the island portions consisting of block B can be dispersed in the epoxy resin at a more uniform nanoscale, thereby obtaining a cured epoxy resin composition with improved peel adhesion and fracture toughness while maintaining transparency.

[0091] The content of block A (i.e., the total content of block A1 and block A2) is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, particularly preferably 45% by mass or more, preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, and particularly preferably 55% by mass or less, based on 100% by mass of the entire block copolymer. By adjusting the content of block A within the above range, a block copolymer having the desired function can be prepared.

[0092] The content of block B is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, particularly preferably 45% by mass or more, preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, and particularly preferably 55% by mass or less, based on 100% by mass of the entire block copolymer. By adjusting the content of block B within the above range, a block copolymer having the desired function can be prepared.

[0093] The weight-average molecular weight (Mw) of the block copolymer is preferably 10,000 or more, more preferably 20,000 or more, even more preferably 30,000 or more, particularly preferably 35,000 or more, preferably less than 200,000, more preferably less than 100,000, even more preferably less than 80,000, and particularly preferably less than 50,000. If the weight-average molecular weight is below the lower limit, the peel adhesion and fracture toughness-imparting properties are insufficient, and if it is above the upper limit, the solubility in the epoxy resin decreases. Therefore, if the weight-average molecular weight is within the above range, a cured epoxy resin composition with improved peel adhesion and fracture toughness can be obtained while maintaining transparency.

[0094] The molecular weight distribution (Mw / Mn) of the block copolymer is preferably 2.0 or less, more preferably 1.6 or less, and even more preferably 1.5 or less. In this invention, the molecular weight distribution (Mw / Mn) is determined by (weight-average molecular weight of the block copolymer (Mw)) / (number-average molecular weight of the block copolymer (Mn)). The smaller the Mw / Mn value, the narrower the molecular weight distribution, resulting in a copolymer with uniform molecular weights, and the narrowest molecular weight distribution is achieved when the value is 1.0. If the molecular weight distribution (Mw / Mv) of the block copolymer exceeds 2.0, it will contain molecules with both small and large molecular weights. This is because if the molecular weight is small, the peel adhesion and fracture toughness-conferring properties will be insufficient, and if the molecular weight is large, the solubility in epoxy resin will decrease, which may result in a loss of transparency and a decrease in mechanical strength.

[0095] In this invention, the weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (hereinafter referred to as "GPC").

[0096] (Method of manufacturing block copolymers) As a method for producing the block copolymer, a first A block (e.g., A1 block) may be produced first by a polymerization reaction of vinyl monomers, the monomer of B block may be polymerized onto the first A block, and then the monomer of the second A block (e.g., A2 block) may be polymerized onto the B block; or the first A block (e.g., A1 block), the second A block (e.g., A2 block), and B block may be produced separately, and then the first A block, B block, and second A block may be coupled together.

[0097] For example, it can be obtained by sequentially polymerizing the vinyl monomers that make up the block using a radical polymerization method. Specifically, a manufacturing method can be described as comprising the steps of: polymerizing the vinyl monomers that make up the first A block (e.g., block A1) to synthesize the first A block; polymerizing the vinyl monomers that make up block B onto the synthesized first A block to synthesize block B; and polymerizing the vinyl monomers that make up the second A block (e.g., block A2) onto the synthesized block B to synthesize block 2A.

[0098] The polymerization method is not particularly limited, but living radical polymerization is preferred. That is, the block copolymer is preferably one polymerized by living radical polymerization. Conventional radical polymerization methods tend to result in deactivation of the growth ends due to termination reactions and chain transfer reactions, as well as initiation and growth reactions, easily producing a mixture of polymers with various molecular weights and heterogeneous compositions. The living radical polymerization method is preferred because, while maintaining the simplicity and versatility of conventional radical polymerization methods, termination reactions and chain transfer are less likely to occur, and the growth ends do not become deactivated during growth, thus facilitating precise control of molecular weight distribution and the production of polymers with a uniform composition.

[0099] Living radical polymerization methods include those that use compounds capable of generating nitroxide radicals (nitroxide method (NMP method)), those that use metal complexes such as copper or ruthenium and use halogenated compounds as polymerization initiators, with polymerization carried out in a living manner from those initiators (ATRP method), those that use dithiocarboxylic acid esters or xantate compounds (RAFT method), those that use organotellurium compounds (TERP method), those that use organiodine compounds (ITP method), and those that use iodine compounds as polymerization initiators and organic compounds such as phosphorus compounds, nitrogen compounds, oxygen compounds, or hydrocarbons as catalysts (reversible transfer catalytic polymerization (RTCP method), reversible catalyst-mediated polymerization (RCMP method)). Among these methods, the TERP method is preferred from the viewpoint of the diversity of monomers that can be used, molecular weight control in the polymer range, uniform composition, and coloration.

[0100] Living radical polymerization, particularly the TERP method, is preferred because the polymer chains react uniformly with the monomers during polymerization, the composition of all polymers becomes nearly uniform, and the probability of forming pseudo-crosslinks increases.

[0101] The TERP method is a method for polymerizing radically polymerizable compounds (vinyl monomers) using an organotellurium compound as a polymerization initiator, and is described, for example, in International Publication Nos. 2004 / 14848, 2004 / 14962, 2004 / 072126, and 2004 / 096870.

[0102] Specific polymerization methods for the TERP method include the following (a) to (d). (a) A method for polymerizing vinyl monomers using an organotellurium compound represented by general formula (2). (b) A method of polymerizing vinyl monomer using a mixture of an organotellurium compound represented by general formula (2) and an azo polymerization initiator. (c) A method of polymerizing vinyl monomer using a mixture of an organic tellurium compound represented by general formula (2) and an organic ditellum compound represented by general formula (3). (d) A method of polymerizing vinyl monomer using a mixture of an organic tellurium compound represented by general formula (2), an azo polymerization initiator, and an organic ditellurium compound represented by general formula (3).

[0103] [ka]

[0104] [In general formula (2), R 3 R represents an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 8 carbon atoms. 4 and R 5 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. 6represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amide group, an oxycarbonyl group, a cyano group, an allyl group or a propargyl group. 〔In general formula (3), R 7 represents an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group.

[0105] The group represented by R 3 is an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group, and specifically, it is as follows. Examples of the alkyl group having 1 to 8 carbon atoms include linear or branched alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, and cyclic alkyl groups such as cyclohexyl group. Preferably, it is a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably, it is a methyl group or an ethyl group. Examples of the aryl group include phenyl group, naphthyl group, etc. Examples of the aromatic heterocyclic group include pyridyl group, furyl group, thienyl group, etc.

[0106] The groups represented by R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and each group is specifically as follows. Examples of the alkyl group having 1 to 8 carbon atoms include linear or branched alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, and cyclic alkyl groups such as cyclohexyl group. Preferably, it is a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably, it is a methyl group or an ethyl group.

[0107] The group represented by R 6The groups represented by are alkyl groups, aryl groups, substituted aryl groups, aromatic heterocyclic groups, alkoxy groups, acyl groups, amide groups, oxycarbonyl groups, cyano groups, allyl groups, or propargyl groups having 1 to 8 carbon atoms, and specifically include the following:

[0108] Examples of C1-C8 alkyl groups include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, and octyl groups, and cyclic alkyl groups such as cyclohexyl groups. Preferably, linear or branched alkyl groups have C1-C4, and more preferably, methyl or ethyl groups.

[0109] Examples of aryl groups include phenyl groups and naphthyl groups. Phenyl groups are preferred.

[0110] Examples of substituted aryl groups include substituted phenyl groups and substituted naphthyl groups. Examples of substituents on substituted aryl groups include halogen atoms, hydroxyl groups, alkoxy groups, amino groups, nitro groups, cyano groups, and -COR groups. 61 The carbonyl-containing group (R) shown by 61 Examples of substituents include alkyl groups, aryl groups, alkoxy groups, or allyloxy groups having 1 to 8 carbon atoms, sulfonyl groups, and trifluoromethyl groups. Furthermore, these substituents are preferably substituted with one or two atoms.

[0111] Examples of aromatic heterocyclic groups include pyridyl groups, furyl groups, and thienyl groups.

[0112] Preferred alkoxy groups are those in which an alkyl group having 1 to 8 carbon atoms is bonded to an oxygen atom. Examples include methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy, tet-butoxy, pentyloxy, hexyloxy, heptyloxy, and octyloxy groups.

[0113] Examples of acyl groups include acetyl groups, propionyl groups, and benzoyl groups.

[0114] As for amide groups, -CONR 621 R 622 (R 621 , R 622 Each of these can independently be a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group.

[0115] As for the oxycarbonyl group, -COOR 63 (R 63 The group is preferably represented by a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group. Examples include a carboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an n-butoxycarbonyl group, a sec-butoxycarbonyl group, a ter-butoxycarbonyl group, an n-pentoxycarbonyl group, and a phenoxycarbonyl group. Preferred oxycarbonyl groups include the methoxycarbonyl group and the ethoxycarbonyl group.

[0116] As for allyl groups, -CR 641 R 642 -CR 643 =CR 644 R 645 (R 641 , R 642 Each is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R 643 , R 644 , R 645 Examples include a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group, where each substituent may be linked in a cyclic structure.

[0117] As for the propargyl group, -CR 651 R 652 -C≡CR 653 (R 651 , R 652 R is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. 653Examples include hydrogen atoms, alkyl groups having 1 to 8 carbon atoms, aryl groups, or silyl groups.

[0118] The organic tellurium compounds represented by general formula (2) specifically include (methylteranylmethyl)benzene, (methylteranylmethyl)naphthalene, ethyl=2-methyl-2-methylteranyl-propionate, ethyl=2-methyl-2-n-butylteranyl-propionate, (2-trimethylsiloxyethyl)=2-methyl-2-methylteranyl-propinate, (2-hydroxyethyl)=2-methyl-2-methylteranyl-propinate, or (3-trimethylsilylpropargyl)=2-methyl-2-methylteranyl-propinate, as well as all the organic tellurium compounds described in International Publication Nos. 2004 / 14848, 2004 / 14962, 2004 / 072126, and 2004 / 096870.

[0119] In general formula (3), R 7 The group represented by is an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 8 carbon atoms, and specifically includes the following: Examples of C1-C8 alkyl groups include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, and octyl groups, as well as cyclic alkyl groups such as cyclohexyl groups. Preferably, it is a linear or branched alkyl group having 1-C4 carbon atoms, and more preferably a methyl or ethyl group. Examples of aryl groups include phenyl and naphthyl groups. Examples of aromatic heterocyclic groups include pyridyl, furyl, and thienyl groups.

[0120] Examples of organic ditellurium compounds represented by general formula (3) include dimethyl ditelluride, diethyl ditelluride, di-n-propyl ditelluride, diisopropyl ditelluride, dicyclopropyl ditelluride, di-n-butyl ditelluride, di-s-butyl ditelluride, di-t-butyl ditelluride, dicyclobutyl ditelluride, diphenyl ditelluride, bis-(p-methoxyphenyl) ditelluride, bis-(p-aminophenyl) ditelluride, bis-(p-nitrophenyl) ditelluride, bis-(p-cyanophenyl) ditelluride, bis-(p-sulfonylphenyl) ditelluride, dinaphthyl ditelluride, or dipyridyl ditelluride.

[0121] Any azo polymerization initiator used in normal radical polymerization can be used without particular restrictions. For example, 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2-methylbutyronitrile) (AMBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis(1-cyclohexanecarbonitride) (ACHN), dimethyl-2,2'-azobisisobutyrate (MAIB), 4,4'-azobis(4-cyanovaleric acid) (ACVA), 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobis(2-methylbutylamide), 2,2'-azobis(4-methoxy- Examples include 2,4-dimethylvaleronitrile) (V-70), 2,2'-azobis(2-methylamidinopropane) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2'-azobis(N-butyl-2-methylpropionamide), or 2,2'-azobis(N-cyclohexyl-2-methylpropionamide).

[0122] In the polymerization methods described in (a), (b), (c), and (d) above, the amount of vinyl monomer used can be adjusted as appropriate depending on the properties of the desired copolymer, but it is generally preferable to use 5 to 10,000 moles of vinyl monomer per mole of the organic tellurium compound of general formula (2).

[0123] In the polymerization method (b) described above, when an organic tellurium compound of general formula (2) and an azo polymerization initiator are used in combination, it is generally preferable that the amount of azo polymerization initiator used is 0.01 mol to 10 mol per 1 mol of the organic tellurium compound of general formula (2).

[0124] In the polymerization method (c) described above, when an organic tellurium compound of general formula (2) and an organic ditellulium compound of general formula (3) are used in combination, it is generally preferable that the amount of organic ditellulium compound of general formula (3) used is 0.01 mol to 100 mol of the organic ditellulium compound of general formula (3) per 1 mol of the organic tellurium compound of general formula (2).

[0125] In the polymerization method (d) described above, when an organic tellurium compound of general formula (2), an organic ditellulium compound of general formula (3), and an azo polymerization initiator are used in combination, the amount of azo polymerization initiator to be used is usually 0.01 mol to 100 mol of azo polymerization initiator per 1 mol total of the organic tellurium compound of general formula (2) and the organic ditellulium compound of general formula (3).

[0126] The polymerization reaction can be carried out without a solvent, but it may also be carried out using an aprotic or protic solvent commonly used in radical polymerization, while stirring the mixture. Examples of usable aprotic solvents include benzene, toluene, anisole, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, acetonitrile, 2-butanone (methyl ethyl ketone), dioxane, hexafluoroisopropaol, propylene glycol monomethyl ether acetate, chloroform, carbon tetrachloride, tetrahydrofuran (THF), N-methyl-2-pyrrolidone (NMP), ethyl acetate, propylene glycol monomethyl ether acetate, or trifluoromethylbenzene. Examples of protic solvents include water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, or diacetone alcohol.

[0127] The amount of solvent used can be adjusted as appropriate. For example, per 1 g of vinyl monomer, the amount is usually in the range of 0.01 ml to 50 ml, preferably in the range of 0.05 ml to 10 ml, and more preferably in the range of 0.1 ml to 1 ml.

[0128] The reaction temperature and reaction time can be adjusted as appropriate depending on the molecular weight or molecular weight distribution of the resulting copolymer, but typically, stirring is performed at 0°C to 150°C for 1 minute to 100 hours. The TERP method can obtain high yields and precise molecular weight distribution even at low polymerization temperatures and short polymerization times.

[0129] After the polymerization reaction is complete, the desired copolymer can be separated from the resulting reaction mixture by conventional separation and purification methods.

[0130] The growth ends of the copolymer obtained by the polymerization reaction are derived from the tellurium compound -TeR 3 (In the formula, R 3The form is the same as described above, and although it is deactivated by handling in air after the polymerization reaction is complete, tellurium atoms may remain. Copolymers with tellurium atoms remaining at the ends may become discolored or have poor thermal stability, so it is preferable to remove the tellurium atoms.

[0131] Methods for removing tellurium atoms include radical reduction methods using tributylstannane or thiol compounds; adsorption methods using activated carbon, silica gel, activated alumina, activated clay, molecular sieves, and polymer adsorbents; adsorption methods using ion exchange resins to remove metals; liquid-liquid extraction or solid-liquid extraction methods that oxidize and decompose tellurium atoms at the copolymer ends by adding hydrogen peroxide or peroxides such as benzoyl peroxide, or by blowing air or oxygen into the system, and then remove residual tellurium compounds by washing with water or using an appropriate solvent; and purification methods in solution, such as limiting filtration, that extract and remove only those molecules below a specific molecular weight. These methods can also be used in combination.

[0132] <Epoxy resin modifier> The epoxy resin modifier of the present invention contains the ABA-type triblock copolymer and is used by being compounded with epoxy resin.

[0133] The epoxy resin modifier of the present invention may contain only the ABA-type triblock copolymer, or it may also contain other components. Other components that may be included in the epoxy resin modifier of the present invention include various known additives such as organic solvents, stabilizers, plasticizers, flame retardants, flame retardant aids, antioxidants, and antistatic agents. The organic solvent is not particularly limited, but examples include xylene, toluene, butanol, ethyl acetate, butyl acetate, N,N-dimethylformamide, methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, and cyclohexanone.

[0134] <Epoxy resin composition> The epoxy resin composition of the present invention contains an epoxy resin, a curing agent, and the epoxy resin modifier of the present invention described above.

[0135] Any conventionally known epoxy resin can be used as the epoxy resin in the present invention. Specific examples include bisphenol-type epoxy resins, phenol novolac-type epoxy resins, orthocresol novolac-type epoxy resins, biphenyl-type epoxy resins, dicyclopentadiene-type epoxy resins, diphenylfluorene-type epoxy resins and their halogen, amino group, or alkyl-substituted derivatives, glycidyl ester-type epoxy resins, naphthalene-type epoxy resins, heterocyclic epoxy resins and other aromatic ring / aliphatic ring-containing epoxy resins, isocyanate-modified epoxy resins, diarylsulfone-type epoxy resins, hydroquinone-type epoxy resins, hydantoin-type epoxy resins, resorcinol diglycidyl ether, triglycidyl-p-aminophenol, m-aminophenol triglycidyl ether, tetraglycidylmethylenedianiline, (trihydroxyphenyl)methane triglycidyl ether, tetraphenylethane tetraglycidyl ether, and other epoxy resins (polyepoxy compounds) containing two or more epoxy groups in their molecules. One or more of the above epoxy resins can be used.

[0136] The epoxy resin is preferably liquid at room temperature (25°C) from the viewpoint of handling and composition preparation. Liquid epoxy resins at room temperature typically have a weight-average molecular weight of 300 to 1000 and an epoxy equivalent of 150 g / eq to 600 g / eq, preferably 150 g / eq to 200 g / eq. Among the epoxy resins, bisphenol-type epoxy resins are preferably used from the viewpoint of handling ease, processability of the curable resin composition, heat resistance, fracture toughness, and peel adhesion strength of the cured resin. Specific examples of bisphenol-type epoxy resins include bisphenol A-type epoxy resin obtained by the reaction of bisphenol A and epichlorohydrin, bisphenol F-type epoxy resin obtained by the reaction of bisphenol F and epichlorohydrin, bisphenol S-type epoxy resin obtained by the reaction of bisphenol S and epichlorohydrin, bisphenol AD-type epoxy resin obtained by the reaction of bisphenol AD ​​and epichlorohydrin, and halogen or alkyl substituted derivatives thereof. Among these, bisphenol A type epoxy resin is more preferably used because it provides superior handling and processability of the curable resin composition, as well as better heat resistance of the cured resin product, and bisphenol A type diglycidyl ether is even more preferably used.

[0137] The type of curing agent used in the present invention is not particularly limited, and any conventional curing agent for epoxy resins can be used. Examples of such curing agents include acid anhydride-based curing agents, amine-based curing agents, and phenol-based curing agents. Among these, acid anhydride-based curing agents and amine-based curing agents are preferred, and acid anhydride-based curing agents are more preferred. An acid anhydride-based curing agent is a curing agent having one or more carboxylic acid anhydride groups per molecule, and the epoxy resin composition is cured by a polycondensation reaction between the epoxy group of the epoxy resin and the carboxylic acid anhydride group. Examples of acid anhydride-based curing agents include cyclic aliphatic acid anhydrides, aromatic acid anhydrides, and aliphatic acid anhydrides, and specifically, maleic anhydride, succinic anhydride, phthalic anhydride, 4-methylphthalic anhydride, 4-methylcyclohexanedicarboxylic acid anhydride, trimellitic anhydride, pyromellitic anhydride, and tetrahydrophthalic anhydride. Amine-based curing agents are curing agents having one or more amine groups per molecule, and the epoxy resin composition hardens through a polycondensation reaction between the epoxy groups of epoxy resins and the amine groups. Examples of amine-based curing agents include cyclic aliphatic amines, aromatic amines, and aliphatic amines, specifically diethylenetriamine, triethylenetetramine, metaxylylenediamine, diaminodiphenylmethane, methanephenyldiamine, and diaminodiphenylsulfone. Examples of phenol-based curing agents include phenol novolac resins. These curing agents may be used individually or in combination of two or more types.

[0138] The content of the curing agent is not particularly limited, but is preferably 5 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 70 parts by mass or more, preferably 250 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less, per 100 parts by mass of epoxy resin. Furthermore, the amount of the curing agent is preferably 0.5 to 2.5 equivalents, and more preferably 0.5 to 1.5 equivalents, relative to the epoxy groups in the epoxy resin composition. This is because if the content of the curing agent is within the above range, the mechanical properties of the cured product of the epoxy resin composition will be improved.

[0139] The epoxy resin composition of the present invention preferably further contains a curing accelerator. Specific examples of curing accelerators include, for example, benzyldimethylamine, cyclohexyldimethylamine, pyridine, triethanolamine, 2-(dimethylaminomethyl)phenol, dimethylpiperazine, 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]nona-5-ene (DBN), and 1,4-diazabicyclo[2.2.2] Octane (DABCO), tertiary amine compounds such as 2,4,6-tris(dimethylaminomethyl)phenol; 2-methylimidazole, 2-ethylimidazole, 2-n-heptylimidazole, 2-n-undecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-(2-cyano Ethyl)-2-methylimidazole, 1-(2-cyanoethyl)-2-n-undecylimidazole, 1-(2-cyanoethyl)-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-di(hydroxymethyl)imidazole, 1-(2-cyanoethyl)-2-phenyl-4,5-di((2'-cyanoethoxy)methyl)imidazole, 1-(2-cyanoethyl) 1-(2-cyanoethyl)-2-n-undecylimidazolium trimellitate, 1-(2-cyanoethyl)-2-phenylimidazolium trimellitate, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazolium trimellitate, 2,4-diamino-6-(2'-methylimidazolyl-(1'))ethyl-s-triazine, 2,4-diamino-6-(2'-n-undecylimidazolyl)ethyl-s-triazine, 2,4-diamino-6-(2'-ethyl-4'-methylimidazolyl-(1' Examples include imidazole compounds such as ethyl-s-triazine, isocyanuric acid adducts of 2-methylimidazole, isocyanuric acid adducts of 2-phenylimidazole, and isocyanuric acid adducts of 2,4-diamino-6-(2'-methylimidazolyl-(1'))ethyl-s-triazine; phosphine compounds such as triphenylphosphine and phosphonium salts such as tetraphenylphosphonium and tetraphenylborate; metal compounds such as tin octylate; and microencapsulated curing accelerators. These may be used individually or in combination of two or more.

[0140] The content of the curing accelerator is not particularly limited, but is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 2 parts by mass, and even more preferably 0.5 to 1.5 parts by mass per 100 parts by mass of epoxy resin. This is because the mechanical properties of the cured product of the epoxy resin composition are improved when the content of the curing accelerator is within the above range.

[0141] In the epoxy resin composition of the present invention, the content of the epoxy resin modifier of the present invention is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, preferably 25 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less, based on the equivalent amount of ABA-type triblock copolymer per 100 parts by mass of the total amount of epoxy resin and curing agent. If the content of the epoxy resin modifier is 1 part by mass or more, a cured product of the epoxy resin composition with excellent fracture toughness and peel adhesion can be obtained. Furthermore, if the content of the epoxy resin modifier is 25 parts by mass or less, it is possible to suppress the deterioration of the epoxy resin's functionality (such as tensile strength and solvent resistance) that occurs when a large amount of epoxy resin modifier is added, while maintaining high transparency.

[0142] The epoxy resin composition of the present invention may contain, in addition to the epoxy resin, curing agent, curing accelerator, and epoxy resin modifier of the present invention, other additives as needed, within a range that does not impair the effects of the present invention.For example, n-butanol glycidyl ether, butyl glycidyl ether, butylphenyl glycidyl ether, hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl glycidyl ether, furfuryl glycidyl ether, trimethoxysilyl glycidyl ether, other higher alcohol-based glycidyl ethers, methacrylate glycidyl esters, etc., as well as reactive diluents such as polyfunctional group 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, dimer acid diglycidyl esters; carbon black such as Ketjenblack, silica, fine calcium carbonate, sepiolite, etc. Thixotropy-inducing agents: Calcium carbonate, talc, magnesia, calcium silicate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, alumina, zircon, graphite, barium sulfate, clay, mica, kaolin, wollastonite, mica, feldspar, syenite, chlorite, bentonite, montmorillonite, barite, cristobalite, dolomite, quartz, diatomaceous earth, aluminum silicate, barium carbonate, magnesium carbonate, zinc carbonate, mineral fibers, textile fibers, glass fibers, aramid pulp, boron fibers, carbon fibers, phosphates, crystalline silica, amorphous silica, fused silica, fumed silica, calcined silica, precipitated silica, crushed (fine powder) Examples include silica such as silica, pyrophyllite, silica sand, cellulose, cement, resin powders such as polyethylene, calcium oxide, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, titanium dioxide, hollow inorganic beads such as hollow ceramic beads and hollow glass beads, hollow organic beads made of polyester resin, glass beads, metal powders, bituminous substances, and other fillers; reaction retardants; anti-aging agents; antioxidants; plasticizers; adhesion promoters; flame retardants; antistatic agents; ultraviolet absorbers; surfactants; dispersants; defoamers; rheology modifiers; polymerization inhibitors; pigments; dyes; coupling agents; ion scavenging agents; mold release agents; thermosetting resins other than epoxy resins; thermoplastic resins, etc.

[0143] The epoxy resin composition of the present invention preferably contains a reactive diluent. Preferred reactive diluents are 1,6-hexanediol diglycidyl ether and butyl glycidyl ether. The content of the reactive diluent in the epoxy resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, preferably 10% by mass or less, and more preferably 7% by mass or less. If the content of the reactive diluent is within the above range, the viscosity of the epoxy resin composition can be reduced while maintaining excellent fracture toughness.

[0144] The method for producing the epoxy resin composition of the present invention is not particularly limited, and any method that can uniformly mix the epoxy resin, curing agent, epoxy resin modifier of the present invention, and optionally a curing accelerator and other additives can be employed. For example, the epoxy resin composition of the present invention can be produced by employing methods such as (1) introducing the epoxy resin into a reactor, heating the solid epoxy resin to a suitable temperature to make it liquid, adding the epoxy resin modifier and dissolving it, adding the curing agent and curing accelerator and mixing them uniformly in a liquid state, and further degassing as necessary; (2) uniformly mixing the epoxy resin, curing agent and curing accelerator and epoxy resin modifier using a mixer or the like, and then melt-kneading them using a hot roll, twin-screw extruder, kneader or the like to produce the epoxy resin composition; or (3) dissolving the epoxy resin, curing agent and curing accelerator and epoxy resin modifier in a solvent such as methyl ethyl ketone, acetone, or toluene to produce a varnish-like epoxy resin composition.

[0145] <Adhesive> The epoxy resin composition of the present invention is useful as an adhesive because it can provide excellent peel-and-stick adhesion. Examples of applications for the adhesive of the present invention include the structure of vehicles such as automobiles, civil engineering and construction, electronic materials, general office use, medical use, and industrial use.

[0146] <Underfill material> In the manufacturing of electronic devices such as semiconductor devices, semiconductor chip mounting is performed by connecting components such as substrates and semiconductor chips, and semiconductor chips with other semiconductor chips, using solder bumps or the like. In this semiconductor chip mounting, a sealing material (underfill material) is used to fill the gaps between components. The epoxy resin composition of the present invention can provide excellent peel adhesion and fracture toughness, making it useful as such an underfill material. Applications of the underfill material of the present invention include semiconductor chip mounting. More specifically, it can be suitably used to fill gaps between semiconductor chips connected by solder bumps or the like and between semiconductor chips themselves.

[0147] The underfill material of the present invention is preferably liquid at room temperature (25°C). The viscosity of the underfill material of the present invention at room temperature (25°C) is preferably 500 mPa·s or more, more preferably 1500 mPa·s or more, even more preferably 2500 mPa·s or more, preferably 6000 mPa·s or less, more preferably 4500 mPa·s or less, and even more preferably 3000 mPa·s or less. This is because if the viscosity of the underfill material is within the above range, the resin can quickly and seamlessly penetrate between the substrate and the semiconductor chip, and diffusion of the resin between penetration and curing can be prevented. The viscosity is measured by the method described below.

[0148] <Cured resin> The cured resin product of the present invention is obtained by curing the epoxy resin composition of the present invention described above.

[0149] When producing a cured resin product using the epoxy resin composition, any of the conventional curing methods for epoxy resin compositions can be used. For example, heat curing, energy ray curing (electron beam curing, ultraviolet curing, etc.), and moisture curing can all be used, and among these, heat curing is preferred from the viewpoint of dispersing the block copolymer.

[0150] If the epoxy resin composition of the present invention is solid at room temperature (25°C), then, for example, after crushing and tableting, it can be cured and molded using conventional molding methods such as transfer molding, compression molding, and injection molding to produce a cured resin product (cured molded article).

[0151] Furthermore, if the epoxy resin composition of the present invention is liquid or varnish-like at room temperature (25°C), a cured resin product suitable for each application can be obtained by applying the epoxy resin composition of the present invention in an appropriate manner, such as pouring it into a mold (molding), pouring it into a container (potting, etc.), coating it onto a substrate (lamination), or impregnating it with fibers (filaments, etc.) (filament winding, etc.), and then heating and curing it.

[0152] The curing temperature and curing time when curing the epoxy resin composition of the present invention may vary depending on the type of epoxy resin and curing agent, but for example, conditions such as a curing temperature of 20°C to 250°C and a curing time of 1 to 24 hours are used.

[0153] The light transmittance of the cured resin product of the present invention is preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more, when the light transmittance of a cured epoxy resin composition without the epoxy resin modifier of the present invention is taken as 100%. This is because a light transmittance of 30% or more results in a cured resin product with excellent transparency.

[0154] The peel adhesion strength (N / 25mm) of the resin cured product of the present invention is preferably 3.5 or higher, more preferably 5.0 or higher, and even more preferably 10.0 or higher. This is because a peel adhesion strength (N / 25mm) of 3.5 or higher results in a resin cured product with excellent peel adhesion properties.

[0155] Fracture toughness (MPa·m) of the resin cured product of the present invention 1 / 2 The fracture toughness (MPa·m) is preferably 0.7 or higher, more preferably 0.8 or higher, and even more preferably 0.9 or higher. 1 / 2This is because setting the ratio to 0.7 or higher results in a resin cured product with excellent fracture toughness.

[0156] The coefficient of linear expansion (coefficient of linear expansion α1 / peel adhesion) of the resin cured product of the present invention is preferably 0.6 or higher, more preferably 0.8 or higher, even more preferably 1 or higher, preferably 15 or lower, more preferably 10 or lower, and even more preferably 5 or lower. This is because if the coefficient of linear expansion with respect to the peel adhesion is within the above range, the temperature cycle resistance is improved.

[0157] The light transmittance, peel adhesion strength, fracture toughness, and coefficient of thermal expansion α1 of the resin cured product of the present invention are measured by the method described below.

[0158] The cured resin product of the present invention can be used in a wide variety of applications where conventional cured epoxy resins are used. Furthermore, due to its high transparency, it can be used in applications where transparency is required. In addition, because it has high peel adhesion and a small coefficient of thermal expansion relative to peel adhesion, it can be used in adhesive applications such as structural bonding for automobiles and underfill materials for semiconductor chip mounting. Because it has excellent fracture toughness, it can also be applied to aerospace materials and sports applications where impacts are likely to occur. [Examples]

[0159] The present invention will be described in detail below based on examples, but the present invention is not limited to these specific examples.

[0160] The meanings of the abbreviations are as follows: BTEE: Ethyl 2-methyl-2-n-butylteranyl propionate DBDT: Dibutylditerlide AIBN: 2,2'-Azobis(isobutyronitrile) THFMA: Tetrahydrofurfuryl methcrate IBMA: Isobutyl methacrylate MMA: Methyl methacrylate LMA: Dodecyl methacrylate

[0161] [Evaluation Method] (Polymerization rate) Using a nuclear magnetic resonance (NMR) spectroscopy system (Bruker BioSpin, model: AVANCE500 (frequency 500MHz)), 1 ¹H-NMR was measured (solvent: deuterated chloroform (CDCl3), internal standard: tetramethylsilane (TMS)). From the obtained NMR spectrum, the integral ratio of the peaks of the vinyl group derived from the monomer and the ester side chain derived from the polymer was determined, and the polymerization rate of the monomer was calculated.

[0162] (Weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn)) The molecular weight was determined by gel permeation chromatography (GPC) using a high-performance liquid chromatograph (Tosoh Corporation, model: HLC-8320GPC). Two TSKgel SuperMultipore HZ-H columns (Φ4.6mm × 150mm) (Tosoh Corporation) were used, with tetrahydrofuran as the mobile phase and a differential refractive index detector. The measurement conditions were a column temperature of 40°C, a sample concentration of 5 mg / mL, a sample injection volume of 10 μL, and a flow rate of 0.35 mL / min. Calibration curves were created using polystyrene (molecular weights 2,890,000, 1,090,000, 706,000, 427,000, 190,000, 96,400, 37,900, 10,200, 2,630, 440) as standard substances, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured. The molecular weight distribution (Mw / Mn) was calculated from these measurements.

[0163] (Viscosity of epoxy resin composition) The viscosity of the epoxy resin composition (before curing) was measured at room temperature (25°C) using an E-type viscometer (product name: TVE-22L, manufactured by Toki Sangyo Co., Ltd.). The cone rotor was set to match the measured viscosity (1°34'x24 for viscosity less than 1500 mPa·s, and 3°xR14 for viscosity 1500 mPa·s or more), the rotor rotation speed was 5 rpm, and the measurement range was set to 5.

[0164] (Transparency of cured epoxy resin compositions) The light transmittance at 600 nm per 6 mm of cured epoxy resin compositions, obtained by heat curing at 120°C for 90 minutes, was measured using a U-3900 spectrophotometer (Hitachi High-Tech Science Corporation). Ten measurements were performed, and the average value of these 10 measurements was used as the light transmittance value. The light transmittance values ​​of the cured epoxy resin compositions in Tables 3 and 5 are indexed values, with the light transmittance of epoxy resin composition No. 13 (without block copolymer) set as 100%. The light transmittance values ​​of the cured epoxy resin compositions No. 14-15 in Table 4 are indexed values, with the light transmittance of epoxy resin composition No. 16 (without block copolymer) set as 100%. The light transmittance values ​​of the cured epoxy resin compositions No. 17-18 in Table 4 are indexed values, with the light transmittance of epoxy resin composition No. 19 (without block copolymer) set as 100%. A larger indexed value indicates superior transparency of the cured epoxy resin composition. If the light transmittance was less than 2%, it was classified as "opaque."

[0165] (Peel adhesion strength of cured epoxy resin composition: N / 25mm) The peel adhesion strength test was conducted in accordance with JIS K6854-3. Specifically, two aluminum plates (A1050P, 0.5mm x 25mm x 200mm) were bent at a 90° angle at 150mm, and an epoxy resin composition was applied to the 150mm portion, and the plates were bonded together to form a T-shape. A 0.2mm spacer was placed between the adhesive layers. After application, the epoxy resin composition was cured by heating at 120°C for 90 minutes. After returning to room temperature, a T-shaped peel test was performed using a Shimadzu Autograph AGS-J mechanical testing machine at a head speed of 100mm / min. Five measurements were taken, and the average value of the five measurements was used as the peel adhesion strength value.

[0166] (Fracture toughness of cured epoxy resin compositions) The epoxy resin composition was poured into a mold measuring 6 x 12 x 25 mm and heated and cured at 120°C for 90 minutes. The resulting cured material was subjected to fracture toughness testing using a Shimadzu Autograph AGS-J mechanical testing machine in accordance with ASTM D5045-93. Ten measurements were performed, and the average value of these 10 measurements was taken as the fracture toughness value. Fracture toughness K1c represents the resistance to crack propagation; a higher value indicates higher fracture toughness.

[0167] (Tensile strength of cured epoxy resin composition) The epoxy resin composition was poured into a mold the size of a No. 3 dumbbell test specimen and heated and cured at 120°C for 90 minutes. The resulting cured material was subjected to a tensile test using a Shimadzu Autograph AGS-J mechanical testing machine in accordance with JIS K 6251. The stress at fracture of the dumbbell test specimen was defined as the tensile strength. Ten measurements were performed, and the average value of these 10 measurements was taken as the tensile strength value.

[0168] (Coefficient of linear expansion of cured epoxy resin composition) The cured product obtained by heating and curing the epoxy resin composition at 120°C for 90 minutes was heated using a thermomechanical analyzer (manufactured by Hitachi High-Tech Science Corporation) from 30°C to 300°C at a rate of 10°C / min. The slope of the tangent line in the resulting chart between 50°C and 80°C was defined as the coefficient of thermal expansion α1 (ppm / °C). Furthermore, the coefficient of thermal expansion with respect to the peel-bonding force was calculated from the coefficient of thermal expansion α1 and the peel-bonding force measured in the peel-bonding force test using the following formula. Coefficient of linear expansion with respect to peel adhesion strength = Coefficient of linear expansion α1 (ppm / ℃) / Peel adhesion strength (N / 25mm)

[0169] (Observation of the dispersion state of low-miscibility components in the cured product of epoxy resin composition) Using a microtome (ULTROTOME (trademark) V, manufactured by LKB BROMMA), cured epoxy resin compositions (No. 2, 10, 6) were cut to a thickness of 60 nm. After staining the cut sections with ruthenium(VIII) oxide (0.5% aqueous solution) to identify the low-miscibility components, the dispersion state of the low-miscibility components was observed using a field emission transmission electron microscope (JEM-2100F, manufactured by JEOL Ltd.) or a field emission scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation), and field emission transmission electron microscope images (FE-TEM images) or field emission scanning electron microscope images (FE-SEM images) were obtained.

[0170] <Synthesis of block copolymers> (Block copolymer No. 1) In a 300 mL reactor with a nitrogen-purged stirrer, 24.38 g of THFMA, 0.63 g of IBMA, 0.74 g of BTEE, 0.41 g of DBDT, 0.0825 g of AIBN, and 25.03 g of toluene were charged and reacted at 60°C for 18.25 hours to polymerize block A1 (first stage polymerization reaction). The polymerization rate was 97.7%.

[0171] To the reaction solution obtained in the first polymerization reaction described above, 50.00 g of LMA, 0.0826 g of AIBN, and 50.01 g of toluene, which had been pre-purged with nitrogen, were added, and the mixture was reacted at 60°C for 29.25 hours to polymerize block B (second polymerization reaction). The polymerization rate was 97.4%.

[0172] To the reaction solution obtained in the second polymerization reaction described above, 24.38 g of THFMA, 0.63 g of IBMA, 0.0823 g of AIBN, and 25.12 g of toluene, which had been pre-purged with nitrogen, were added, and the mixture was reacted at 60°C for 40.00 hours to polymerize the A2 block (third polymerization reaction). The polymerization rate was 99.6%. After the reaction was complete, the reaction solution was diluted with THF (tetrahydrofuran) and poured into methanol under stirring. The precipitated polymer was pressure filtered and dried to obtain ABA-type triblock copolymer No. 1. The Mw of block copolymer No. 1 was 46900, and the Mw / Mn ratio was 1.27.

[0173] (Block copolymer No. 2-11) Block copolymers No. 2 to 11 were produced in the same manner as block copolymer No. 1, except that the polymerization reaction was carried out using the raw material amounts and reaction conditions shown in Table 1. Block copolymers No. 6, 8, and 10 were AB-type diblock copolymers obtained without carrying out the third polymerization reaction.

[0174] Table 1 shows the raw material monomers, organotellurium compounds, organoditellurium compounds, azo polymerization initiators, solvents, reaction conditions, and polymerization rate used. Table 2 shows the composition, Mw, and Mw / Mn of the block copolymer. The content of each structural unit in the block copolymer was calculated from the charge ratio and polymerization rate of the monomers used in the polymerization reaction.

[0175] [Table 1]

[0176] [Table 2]

[0177] <Manufacturing of epoxy resin compositions> (Epoxy resin compositions No. 1-3, 5-12) A mixture of 49.77% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent weight 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation), 45.28% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.0 equivalents relative to the epoxy resin), 0.47% by mass of 2-ethyl-4-methylimidazole as a curing accelerator, and the block copolymer obtained above as an epoxy resin modifier in the mass percentages listed in Table 3 was mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin compositions No. 1 to 12.

[0178] (Epoxy resin composition No. 4) 47.57% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent weight 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation), 43.28% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.0 equivalents relative to the epoxy resin), 0.45% by mass of 2-ethyl-4-methylimidazole as a curing accelerator, and the block copolymer obtained above as an epoxy resin modifier in the mass percentages listed in Table 3 were mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin composition No. 4.

[0179] (Epoxy resin composition No. 13) 52.23% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent weight 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation), 47.27% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.1 equivalents relative to the epoxy resin), and 0.49% by mass of 2-ethyl-4-methylimidazole as a curing accelerator were mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin composition No. 13.

[0180] (Epoxy resin compositions No. 14-15) A mixture of 47.48% by mass of bisphenol F type epoxy resin (product name: jER (trademark registered) 807, epoxy equivalent weight 168 g / eq, weight-average molecular weight 336, manufactured by Mitsubishi Chemical Corporation), 47.57% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.0 equivalents relative to the epoxy resin), 0.48% by mass of 2-ethyl-4-methylimidazole as a curing accelerator, and block copolymer No. 2 or No. 4 obtained above as an epoxy resin modifier was mixed in the mass percentages shown in Table 4. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin compositions No. 14 to 15.

[0181] (Epoxy resin composition No. 16) 49.70% by mass of bisphenol F type epoxy resin (product name: jER (trademark registered) 807, epoxy equivalent weight 168 g / eq, weight-average molecular weight 336, manufactured by Mitsubishi Chemical Corporation), 49.80% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.0 equivalents relative to the epoxy resin), and 0.50% by mass of 2-ethyl-4-methylimidazole as a curing accelerator were mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin composition No. 16.

[0182] (Epoxy resin compositions No. 17-18) 75.65% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation), 19.87% by mass of diaminodiphenylmethane as a curing agent (1.0 equivalent relative to the epoxy resin), and the block copolymer No. 2 or No. 5 obtained above as an epoxy resin modifier were mixed in the mass percentages shown in Table 4. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin compositions No. 17 to 18.

[0183] (Epoxy resin composition No. 19) 79.2% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation) and 20.8% by mass of diaminodiphenylmethane (1.0 equivalent relative to the epoxy resin) as a curing agent were mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin composition No. 19.

[0184] (Epoxy resin composition No. 20) 47.51% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent weight 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation), 43.22% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.0 equivalents relative to the epoxy resin), 0.45% by mass of 2-ethyl-4-methylimidazole as a curing accelerator, and the block copolymer obtained above and reactive diluents as epoxy resin modifiers in the mass percentages listed in Table 5 were mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin composition No. 20.

[0185] (Epoxy resin composition No. 21) 48.36% by mass of bisphenol A type epoxy resin (product name: jER (trademark registered) 828, epoxy equivalent weight 194 g / eq, weight-average molecular weight 370, manufactured by Mitsubishi Chemical Corporation), 44.00% by mass of 4-methylcyclohexane-1,2-dicarboxylic acid anhydride as a curing agent (2.0 equivalents relative to the epoxy resin), 0.46% by mass of 2-ethyl-4-methylimidazole as a curing accelerator, and the block copolymer obtained above and reactive diluents as epoxy resin modifiers in the mass percentages listed in Table 5 were mixed. The mixture was stirred and defoamed for 22 minutes using a stirring and defoaming machine (AR-250, manufactured by Thinky Co., Ltd.) to obtain epoxy resin composition No. 21.

[0186] Tables 3 to 5 show the viscosity of the epoxy resin compositions and the evaluation results of the cured products obtained by curing the epoxy resin compositions. Furthermore, the tensile strength of the cured product of epoxy resin composition No. 2 was 36.02 MPa, the tensile strength of the cured product of epoxy resin composition No. 8 was 36.78 MPa, and the tensile strength of the cured product of epoxy resin composition No. 13 was 36.99 MPa.

[0187] [Table 3]

[0188] [Table 4]

[0189] [Table 5]

[0190] The results shown in Tables 3-5 indicate that even when the epoxy resin modifier of the present invention is blended in a small amount (less than 10 parts by mass) per 100 parts by mass of epoxy resin and curing agent, the cured epoxy resin composition exhibits high transparency while also demonstrating excellent fracture toughness and peel adhesion. Furthermore, because fracture toughness and peel adhesion can be significantly increased with a small amount of additive, the degradation of functions such as tensile strength of the epoxy resin that occurs with the addition of large amounts of epoxy resin modifier can be suppressed.

[0191] Furthermore, the results of observing the dispersion state of low-miscibility components in the cured epoxy resin compositions (No. 2, 10, and 6) using an electron microscope are shown in Figures 1 to 3.

[0192] Figure 1 shows a field emission transmission electron microscope (FE-TEM) image (black areas represent the low-miscibility components) of the cured epoxy resin composition No. 2. As shown in Figure 1, the low-miscibility components in the cured epoxy resin composition No. 2 are dispersed in string-like structures with a width (diameter) of approximately 10 nm and a length of approximately 100 nm to 500 nm. Due to the small width of approximately 10 nm, cavitation is likely to occur in the cured material when cracks propagate, and because of the large volume, stress relaxation is possible over a large area.

[0193] Figure 2 shows an FE-TEM image of the cured epoxy resin composition No. 10 (the black areas represent the low-miscibility components). As shown in Figure 2, in the cured epoxy resin composition No. 10, some of the low-miscibility components are in the form of strings, but the majority are dispersed in spherical shapes with a diameter of approximately 10 nm. Therefore, the region in which stress relaxation is possible is considered to be small.

[0194] Figure 3 shows an electro-emission scanning electron microscope (FE-SEM) image of the cured epoxy resin composition No. 6 (white areas represent the low-miscibility components). As shown in Figure 3, in the cured epoxy resin composition No. 6, the low-miscibility components are dispersed at a macroscopic size while incorporating the epoxy resin matrix. Therefore, it is thought that cavitation during crack propagation is less likely to occur in the cured product. [Industrial applicability]

[0195] The epoxy resin modifier of the present invention is used by being compounded with epoxy resin. By compounding the epoxy resin modifier of the present invention with epoxy resin, it is possible to enhance the fracture toughness and peel adhesion of the epoxy resin while maintaining the high transparency of the epoxy resin. Epoxy resin compositions containing the epoxy resin modifier of the present invention can be used in a wide variety of applications where conventional epoxy resins are used. Furthermore, due to its high transparency, it can be used in applications where transparency is required. In addition, because of its high peel adhesion, it can be used in adhesive applications such as structural bonding for automobiles and underfill materials for semiconductor chip mounting. Furthermore, because it has excellent fracture toughness, it can be applied to aerospace materials and sports applications that are prone to impact.

[0196] A preferred embodiment of the present invention is an epoxy resin modifier containing a block copolymer, wherein the block copolymer is an ABA-type triblock copolymer having a block A having a structural unit (a-1) represented by the following general formula (1) and a structural unit (a-2) derived from a (meth)acrylate having a chain-like alkyl group, and a block B having a structural unit (b) derived from at least one vinyl monomer selected from the group consisting of (meth)acrylate having a chain-like alkyl group and (meth)acrylate having a cyclic alkyl group. The content of structural unit (a-1) represented by the general formula (1) in each A block is 85% by mass or more and less than 100% by mass in 100% by mass of A block, and the content of structural unit (a-2) derived from (meth)acrylate having the chain-like alkyl group is greater than 0% by mass and 15% by mass or less in 100% by mass of A block. [ka] [In general formula (1), R 1 Q is a hydrogen atom or a methyl group. 0 ≤ n ≤ 10, and Q is a cyclic ether group or cyclic thioether group of 4-membered to 6-membered rings.

[0197] A preferred embodiment 2 of the present invention is the epoxy resin modifier according to embodiment 1, wherein the structural unit (a-2) of block A is a structural unit derived from a (meth)acrylate having a branched alkyl group.

[0198] A preferred embodiment 3 of the present invention is an epoxy resin modifier according to embodiment 1 or 2, wherein the structural unit (a-1) of block A is derived from at least one selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, morpholino (meth)acrylate, morpholinoethyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, and 1,3-dioxane-(meth)acrylate.

[0199] A preferred embodiment 4 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 3, wherein, among the two A blocks constituting the block copolymer, the A block with a high content of structural unit (a-1) is designated as A1 block, and the A block with a low content of structural unit (a-1) is designated as A2 block, and the mass ratio of A1 block to A2 block (A1 block / A2 block) is 0.8 to 1.2.

[0200] A preferred embodiment 5 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 4, wherein the content of block A is 30% to 70% by mass in 100% by mass of the entire block copolymer.

[0201] A preferred embodiment 6 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 5, wherein the structural unit (b) of block B is a structural unit derived from a (meth)acrylate having a chain-like alkyl group with 11 to 20 carbon atoms.

[0202] A preferred embodiment 7 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 6, wherein the content of structural unit (b) of block B is 80% by mass or more and 100% by mass or less in 100% by mass of block B.

[0203] A preferred embodiment 8 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 7, wherein the content of the B block is 30% to 70% by mass in 100% by mass of the entire block copolymer.

[0204] A preferred embodiment 9 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 8, wherein the weight-average molecular weight (Mw) of the block copolymer is 10,000 or more and less than 200,000.

[0205] A preferred embodiment 10 of the present invention is an epoxy resin modifier according to any one of claims 1 to 9, wherein the molecular weight distribution (Mw / Mn) of the block copolymer is 2.0 or less.

[0206] A preferred embodiment 11 of the present invention is an epoxy resin modifier according to any one of embodiments 1 to 10, wherein the block copolymer is polymerized by living radical polymerization.

[0207] A preferred embodiment 12 of the present invention is an epoxy resin composition containing an epoxy resin, a curing agent, and an epoxy resin modifier according to any one of embodiments 1 to 11.

[0208] A preferred embodiment 13 of the present invention is the epoxy resin composition according to embodiment 12, wherein the content of the epoxy resin modifier is 1 to 25 parts by mass per 100 parts by mass of the total amount of epoxy resin and curing agent, in terms of the amount of the ABA-type triblock copolymer.

[0209] A preferred embodiment 14 of the present invention is an adhesive comprising the epoxy resin composition described in embodiment 12 or 13.

[0210] A preferred embodiment 15 of the present invention is an underfill material comprising the epoxy resin composition described in embodiment 12 or 13.

[0211] A preferred embodiment 16 of the present invention is a cured resin product obtained by curing the epoxy resin composition described in embodiment 12 or 13.

Claims

1. An epoxy resin modifier containing a block copolymer, The block copolymer is an A-B-A type triblock copolymer having a block A having a structural unit (a-1) represented by the following general formula (1) and a structural unit (a-2) derived from a (meth)acrylate having a chain-like alkyl group, and a block B having a structural unit (b) derived from at least one vinyl monomer selected from the group consisting of (meth)acrylate having a chain-like alkyl group and (meth)acrylate having a cyclic alkyl group. An epoxy resin modifier characterized in that the content of structural unit (a-1) represented by the general formula (1) in each A block is 85% by mass or more and less than 100% by mass in 100% by mass of A block, and the content of structural unit (a-2) derived from (meth)acrylate having the chain alkyl group is greater than 0% by mass and 15% by mass or less in 100% by mass of A block. 【Chemistry 1】 [In general formula (1), R １ Q is a hydrogen atom or a methyl group. 0 ≤ n ≤ 10, and Q is a cyclic ether group or cyclic thioether group with a 4-membered to 6-membered ring.

2. The epoxy resin modifier according to claim 1, wherein the structural unit (a-2) of block A is a structural unit derived from a (meth)acrylate having a branched alkyl group.

3. The epoxy resin modifier according to claim 1, wherein the structural unit (a-1) of block A is derived from at least one selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, morpholino (meth)acrylate, morpholinoethyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, and 1,3-dioxan-(meth)acrylate.

4. The epoxy resin modifier according to claim 1, wherein, of the two A blocks constituting the block copolymer, the A block with a high content of structural unit (a-1) is designated as A1 block, and the A block with a low content of structural unit (a-1) is designated as A2 block, and the mass ratio of A1 block to A2 block (A1 block / A2 block) is 0.8 to 1.

2.

5. The epoxy resin modifier according to claim 1, wherein the content of block A is 30% to 70% by mass in 100% by mass of the entire block copolymer.

6. The epoxy resin modifier according to claim 1, wherein the structural unit (b) of block B is a structural unit derived from a (meth)acrylate having a chain-like alkyl group with 11 to 20 carbon atoms.

7. The epoxy resin modifier according to claim 1, wherein the content of structural unit (b) of block B is 80% by mass or more and 100% by mass or less in 100% by mass of block B.

8. The epoxy resin modifier according to claim 1, wherein the content of block B is 30% to 70% by mass in 100% by mass of the entire block copolymer.

9. The epoxy resin modifier according to claim 1, wherein the weight-average molecular weight (Mw) of the block copolymer is 10,000 or more and less than 200,000.

10. The epoxy resin modifier according to claim 1, wherein the molecular weight distribution (Mw / Mn) of the block copolymer is 2.0 or less.

11. The epoxy resin modifier according to claim 1, wherein the block copolymer is polymerized by living radical polymerization.

12. An epoxy resin composition comprising an epoxy resin, a curing agent, and an epoxy resin modifier according to any one of claims 1 to 11.

13. The epoxy resin composition according to claim 12, wherein the content of the epoxy resin modifier is 1 to 25 parts by mass per 100 parts by mass of the total amount of epoxy resin and curing agent, in terms of the equivalent amount of the A-B-A type triblock copolymer.

14. An adhesive comprising the epoxy resin composition described in claim 12.

15. An underfill material comprising the epoxy resin composition described in claim 12.

16. A cured resin product obtained by curing the epoxy resin composition according to claim 12.

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