Resin composition

Abstract

The present invention pertains to a resin composition containing a resin and composite particles having polymer graft chains on the surface of inorganic particles, wherein the average particle size of the inorganic particles is more than 200 nm but no more than 3000 nm, and the resin satisfies at least one of the following conditions (1) to (3). [(1) The resin is a curable resin; (2) the resin is a thermoplastic resin having a glass transition point Tg of 135°C or higher; and (3) the resin is a thermoplastic resin having a melting point Tm of 230°C or higher.]. The present invention makes it possible to provide a resin composition containing composite particles having excellent dispersibility in a resin that is difficult to melt and knead.

Description

resin composition

[0001] The present invention relates to a resin composition containing composite particles and inorganic particles.

[0002] In recent years, there has been a demand for miniaturization of electronic devices, faster signal transmission, and higher wiring density. Therefore, resin compositions used in these components are required to have excellent dielectric properties. For example, Patent Document 1 discloses a curable resin composition containing polyphenylene ether and inorganic particles, and a curable resin composition that gives a cured product exhibiting excellent dielectric properties and moldability has been studied.

[0003] Patent No. 6163292

[0004] The present invention relates to the following items [1] to

[17] . [1] A resin composition containing composite particles having polymer graft chains on the surfaces of inorganic particles, and a resin, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin having a melting point, Tm, of 230°C or higher. [2] The resin composition according to item [1] above, wherein the resin is an epoxy resin, a modified polyphenylene ether resin, a fluororesin, a cycloolefin resin, or a polyimide resin. [3] The graft density of the polymer graft chains is 0.01 chains / nm ２The resin composition according to any one of [1] to [2], wherein the polymer graft chain contains, as a monomer unit, one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, fluorine-based monomers, unsaturated olefin-based monomers, conjugated diene-based monomers, and monomers having an amino group, a hydroxy group, or a glycidyl group. [5] The resin composition according to any one of [1] to [4], wherein the number average molecular weight of a side chain of the polymer graft chain is 10 or more and 1,000 or less. [6] The resin composition according to any one of [1] to [5], wherein the inorganic particles are silica, and the total content of alkali metals and alkaline earth metals relative to the content of silica in the inorganic particles is 50 ppm by mass or less. [7] The resin composition according to any one of [1] to [6], wherein the composite particles have a dielectric loss tangent tanδ of less than 0.01 at a frequency of 10 GHz and a temperature of 25°C. [8] The resin composition according to any one of [1] to [7], wherein the composite particles have the polymer graft chain via a structure represented by the following formula (A): (polymer graft chain)-X-(CH ２ ) ｍ -Si-(R １ ) (R ２ ) (R ３ ) Formula (A) (In formula (A), -X- is a divalent group, one of which is -(CH ２ ) ｍ The other bonded to the polymer graft chain. m is an integer of 0 to 12. R １ , R ２ and R ３At least one of the groups bonded to the particles by forming a metalloxane bond, and those not bonded to the particles are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, a hydrogen atom, a hydroxy group, or a halogen atom.) [9] The resin composition according to any one of [1] to [8] above, wherein the polymer graft chain contains 10% by mass or more of one or more monomer units selected from the group consisting of styrene, divinylbenzene, glycidyl methacrylate, allyl methacrylate, and cyclohexyl methacrylate.

[10] The resin composition according to any one of [1] to [9] above, wherein the resin is an epoxy resin, and the polymer graft chain contains 50% by mass or more of monomer units having an SP value of 10 or more and 12 or less.

[11] The resin composition according to any one of [1] to [9] above, wherein the resin is a modified polyphenylene ether resin, and the polymer graft chain contains 50% by mass or more of monomer units having an SP value of 8 or more and 10 or less.

[12] The resin composition according to any one of [1] to

[11] above, which is a low dielectric resin composition.

[13] The resin composition according to any one of [1] to

[11] above, which is a resin composition for low dielectric materials.

[14] The resin composition according to any one of [1] to

[11] above, which is for use in copper-clad laminates, interlayer insulating films, or primary mounting underfill materials.

[15] A method for producing a resin composition, comprising a step of mixing or kneading composite particles having polymer graft chains on the surfaces of inorganic particles, and a resin, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin having a melting point, Tm, of 230°C or higher.

[16] Use of composite particles having polymer graft chains on the surfaces of inorganic particles and a resin as a resin composition, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) The resin is a curable resin.(2) A thermoplastic resin having a glass transition point, Tg, of 135° C. or higher. (3) A thermoplastic resin having a melting point, Tm, of 230° C. or higher.

[17] Use of the resin composition according to any one of [1] to

[11] above for a copper-clad laminate, an interlayer insulating film, or a primary mounting underfill material.

[0005] Fig. 1 is a schematic diagram showing an example of bonding between inorganic particles and polymer graft chains in a composite particle. １ , R ２ and R ３ It is assumed that all of the above forms a siloxane bond with the silica of the inorganic particle. In Figure 1, the area surrounded by the dashed line between the inorganic particle and the polymer graft chain corresponds to X in formula (A). Detailed Description of the Invention

[0006] However, since the dispersibility of inorganic particles in organic resins is low, even when the two are mixed, the inorganic particles often settle over time or aggregate with each other, and the performance improvement expected by blending inorganic particles tends to be difficult to achieve. Furthermore, curable resins, thermoplastic resins with a melting point of 230°C or less, or thermoplastic resins without a glass transition point are difficult to melt-knead, making it difficult to disperse inorganic particles.

[0007] The present invention has been made in view of the above circumstances, and relates to providing a resin composition containing composite particles that are excellent in dispersibility in a resin that is difficult to melt-knead.

[0008] According to the present invention, it is possible to provide a resin composition containing composite particles that have excellent dispersibility in a resin that is difficult to melt-knead.

[0009] As a result of investigations, the present inventors have found that the use of composite particles having polymer graft chains on the surface of solid or hollow inorganic particles can improve the dispersibility of the particles in resin. While the mechanism by which this effect is achieved is unclear, it is presumed that the entanglement and interaction of the polymer graft chains, which have high affinity with the matrix resin, improves the dispersibility of the composite particles. Therefore, the use of composite particles having such polymer graft chains on the surface of inorganic particles can be expected to improve the dielectric properties, surface smoothness, low thermal expansion, high rigidity, vibration damping, adhesion, and viscosity reduction of resin compositions and their cured products (resin molded articles).

[0010] The resin composition of the present invention contains specific composite particles and a specific resin.

[0011] <Composite Particles> The composite particles are inorganic particles having polymer graft chains on the surfaces thereof, and the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm.

[0012] [Inorganic Particles] As the inorganic particles, inorganic particles known as fillers can be used, including inorganic particles such as metal oxides, metal oxide salts, metal hydroxides, and metal carbonates, preferably one or more selected from the group consisting of metal oxides, metal oxide salts, metal hydroxides, and metal carbonates, more preferably one or more selected from the group consisting of silicon oxides such as silica, and silicates such as mica and talc, and even more preferably silica. The shape of the particles is not particularly limited, and examples thereof include plate-like, granular, needle-like, and fibrous shapes.

[0013] The average particle size of the inorganic particles is greater than 200 nm, preferably 300 nm or more, more preferably 400 nm or more, even more preferably 500 nm or more, and even more preferably 700 nm or more, from the viewpoint of obtaining a molded product of the resin composition exhibiting the desired dielectric properties. On the other hand, from the viewpoint of improving the appearance of the resin composition, the average particle size of the inorganic particles is 3,000 nm or less, more preferably 2,500 nm or less, even more preferably 2,000 nm or less, even more preferably 1,500 nm or less, even more preferably 1,200 nm or less, and even more preferably 1,100 nm or less. The reason why the average particle size of the inorganic particles is greater than 200 nm is that as the average particle size decreases, the specific surface area increases, and in the case of silica, the amount of surface SiOH increases, which increases the dielectric loss tangent, presumably making it unsuitable for use in low-dielectric materials. Furthermore, a small particle size may increase viscosity and deteriorate processability. Furthermore, as the particle size decreases, particles tend to approach and contact each other more easily, resulting in greater agglomeration. In addition, it is presumed that one of the reasons for the tendency for aggregation is the strengthening of interactions between particles due to inertial forces and gravity. For this reason, even if polymer graft chains are attached, if the average particle size is smaller than a predetermined range, it is presumed that dispersibility will decrease, and it is considered that special improvements to the graft chains will be necessary to improve the dispersibility of such particles. In the present invention, the average particle size of inorganic particles refers to the average particle size on a volume basis. The average particle size of inorganic particles is measured by the method described in the Examples below.

[0014] When the inorganic particles are silica, the total content of alkali metals and alkaline earth metals relative to the content of silica in the inorganic particles is preferably small from the viewpoint of exhibiting desired dielectric properties. Specifically, the total content is preferably 50 ppm by mass or less, more preferably 30 ppm by mass or less, and even more preferably 10 ppm by mass or less. The total content is measured by the method described in the Examples below.

[0015] The inorganic particles may be particles having pores, i.e., hollow particles, or particles without pores, i.e., solid particles. Hollow particles and solid particles may be used in combination as inorganic particles. From the viewpoint of dielectric properties, hollow particles are preferred. When pores are present, the porosity is preferably 50% by volume or more, more preferably 55% by volume or more, and even more preferably 60% by volume or more, from the viewpoint of obtaining a molded article of the resin composition exhibiting desired dielectric properties. On the other hand, from the viewpoint of the mechanical strength of the particles, the porosity of the particles is preferably 80% by volume or less, more preferably 77% by volume or less, and even more preferably 74% by volume or less. The porosity of the inorganic particles is measured by the method described in the Examples below.

[0016] Commercially available inorganic particles can be used, and when hollow silica particles are used, they can be produced by a known method, for example, the method described below.

[0017] [Method for producing hollow silica particles] Hollow silica particles can be produced by a method including, for example, the following steps: Step A: A step of preparing an aqueous emulsion of a hydrophobic liquid using a cationic surfactant A; Step B: A step of adding a silanol precursor, an alkaline substance, and a cationic surfactant B to the aqueous emulsion obtained in Step A to produce a hollow silica particle precursor; Step C: A step of heat-treating the hollow silica particle precursor obtained in Step B at a temperature higher than 1000°C and not higher than 1200°C for 1 hour or longer.

[0018] In step A, cationic surfactant A and a hydrophobic liquid are mixed with and stirred in a liquid A containing water to prepare an aqueous emulsion of the hydrophobic liquid in which droplets of the hydrophobic liquid are dispersed. The preparation of the aqueous emulsion of the hydrophobic liquid can be carried out by a general method.

[0019] Examples of water contained in liquid A include distilled water, ion-exchanged water, and ultrapure water. Liquid A may also contain a water-compatible organic solvent, from the viewpoint of more uniform and stable emulsification of the hydrophobic liquid. Examples of water-compatible organic solvents include lower alcohols such as methanol, ethanol, and isopropyl alcohol, and acetone. The water content in liquid A is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass, from the viewpoint of instantly reducing the solubility of the hydrophobic liquid in liquid A.

[0020] Cationic Surfactant A From the viewpoint of facilitating the formation of a complex with the condensed silanol in Step B described below, and from the viewpoint of decomposition and volatilization in Step C described below, the cationic surfactant A is preferably a quaternary ammonium salt, more preferably at least one selected from alkyltrimethylammonium salts and dialkyldimethylammonium salts, and even more preferably at least one selected from the group consisting of quaternary ammonium salts represented by the following general formula (i) or general formula (ii): [R １ R ３ ３ N] ＋ X － (i) [R １ R ２ R ３ ２ N] ＋ X － (ii)

[0021] In the general formula (i) and the general formula (ii), R １ and R ２ each independently represents a linear or branched alkyl group having 4 to 22 carbon atoms; R ３ represents an alkyl group having 1 to 3 carbon atoms, and a plurality of R ３ may each be a different group, and X －represents a monovalent anion. Examples of alkyl groups having 4 to 22 carbon atoms include various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, and various eicosyl groups. Examples of alkyl groups having 1 to 3 carbon atoms include methyl groups, ethyl groups, n-propyl groups, and isopropyl groups. In general formula (i) and general formula (ii), R ３ is preferably a methyl group.

[0022] X in general formulas (i) and (ii) － is preferably at least one monovalent anion selected from halogen ions, hydroxide ions, nitrate ions, etc., from the viewpoint of easy decomposition and volatilization during firing. － The cation is more preferably a halide ion, and even more preferably a chloride ion.

[0023] Examples of the alkyltrimethylammonium salt represented by general formula (i) include butyltrimethylammonium chloride, hexyltrimethylammonium chloride, octyltrimethylammonium chloride, decyltrimethylammonium chloride, lauryltrimethylammonium chloride (dodecyltrimethylammonium chloride), tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, butyltrimethylammonium bromide, hexyltrimethylammonium bromide, octyltrimethylammonium bromide, decyltrimethylammonium bromide, lauryltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, stearyltrimethylammonium bromide, and behenyltrimethylammonium bromide.

[0024] Examples of the dialkyldimethylammonium salt represented by general formula (ii) include dibutyldimethylammonium chloride, dihexyldimethylammonium chloride, dioctyldimethylammonium chloride, dihexyldimethylammonium bromide, dioctyldimethylammonium bromide, dilauryldimethylammonium bromide, and ditetradecyldimethylammonium bromide.

[0025] From the viewpoint of facilitating the formation of a complex with the condensed silanol in step B and facilitating decomposition and volatilization in step C, the quaternary ammonium salt is preferably lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, or behenyltrimethylammonium chloride, and more preferably stearyltrimethylammonium chloride or behenyltrimethylammonium chloride.

[0026] Hydrophobic Liquid The hydrophobic liquid is preferably one that can form emulsified droplets (emulsified oil droplets) in water. Furthermore, in view of using liquid A containing water as the dispersion medium and improving the utilization efficiency of the hydrophobic liquid, the temperature range in the liquid state is preferably 0 to 100°C, and more preferably 20 to 90°C. Specific examples of hydrophobic liquids include those described in paragraphs

[0015] to

[0023] of JP 2016-121060 A. Among these, hydrocarbons having 6 to 18 carbon atoms are preferred, hydrocarbons having 8 to 14 carbon atoms are more preferred, and dodecane is more preferred.

[0027] In step A, the mass ratio of the hydrophobic liquid to water [hydrophobic liquid / water] is preferably 0.3 or more, more preferably 0.35 or more, even more preferably 0.4 or more, from the viewpoint of keeping the particle size of the resulting droplets of the hydrophobic liquid within an appropriate range, and is preferably 0.8 or less, more preferably 0.75 or less, even more preferably 0.7 or less.

[0028] In step A, the mass ratio of cationic surfactant A to the hydrophobic liquid [cationic surfactant A / hydrophobic liquid] is, from the viewpoint of dispersing the hydrophobic liquid in liquid A, preferably 0.0005 or more, more preferably 0.001 or more, even more preferably 0.0015 or more, and is preferably 0.05 or less, more preferably 0.04 or less, even more preferably 0.035 or less.

[0029] In step A, the particle size of the resulting droplets containing the hydrophobic liquid can be adjusted to an appropriate range by appropriately adjusting the stirring speed, temperature, etc. Step A is preferably carried out at a temperature of 15° C. to 80° C. From the viewpoint of adjusting the average particle size of the hollow silica particles to the above range, the volume average particle size of the droplets containing the hydrophobic liquid is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.4 μm or more, and is preferably 2.5 μm or less, more preferably 2.0 μm or less, even more preferably 1.5 μm or less.

[0030] Step B In step B, a silanol precursor, an alkaline substance, and a cationic surfactant B are added to the aqueous emulsion obtained in step A to produce hollow silica particle precursors. Specifically, the silanol precursor present on the surface of the hydrophobic liquid droplets is first hydrolyzed in the presence of an alkaline substance to obtain silanols. The obtained silanols are then condensed in the presence of the alkaline substance to form hollow silica particle precursors having an outer shell containing silica and the cationic surfactant B on the surface of the hydrophobic liquid droplets and containing the hydrophobic liquid inside.

[0031] The silanol precursor, the alkaline substance, and the cationic surfactant B may be added to the aqueous emulsion by adding the silanol precursor and the cationic surfactant B to the aqueous emulsion simultaneously or separately, or by adding the aqueous emulsion to either the silanol precursor or the cationic surfactant B and then adding the other.

[0032] Step B may include, after the formation of the hollow silica particle precursor and before Step C, a step of isolating the hollow silica particle precursor and a step of drying the hollow silica particle precursor. The hollow silica particles can be isolated by, for example, filtration. Furthermore, if the boiling point of the hydrophobic liquid contained in the hollow silica particle precursor is higher than 100°C, the hollow silica particle precursor can be dried by, for example, heating to a temperature of 100°C or higher and lower than the boiling point of the hydrophobic liquid. If the boiling point of the hydrophobic liquid contained in the hollow silica particle precursor is 100°C or lower, the hollow silica particle precursor can be dried by, for example, freeze-drying or the like.

[0033] Silanol Precursor The silanol precursor is a compound that generates a silanol compound by hydrolysis of an alkoxysilane or the like, and is preferably selected from alkyl orthosilicate esters and alkyl pyrosilicate esters. Specific examples include compounds represented by the following general formulas (iii) to (vii), or combinations thereof: SiY ４ (iii) R ３ SiY ３ (iv) R ３ ２ SiY ２ (v) R ３ ３ SiY (vi)Y ３ Si—O—SiY ３ (vii)

[0034] In general formulas (iii) to (vii), R ３ each independently represents an organic group in which a carbon atom is directly bonded to a silicon atom, and Y represents a monovalent hydrolyzable group that becomes a hydroxy group upon hydrolysis.

[0035] In general formulas (iv) to (vi), R ３ are each independently a hydrocarbon group preferably having 1 to 22 carbon atoms in which some of the hydrogen atoms may be substituted with fluorine atoms, and from the viewpoint of improving the utilization efficiency of the hydrophobic organic substance, are preferably an alkyl group, a phenyl group, or a benzyl group having 1 to 22 carbon atoms, more preferably 4 to 18 carbon atoms, and even more preferably 8 to 16 carbon atoms.

[0036] In general formulas (iii) to (vii), Y is preferably an alkoxy group having 1 to 8 carbon atoms or a halogen group excluding fluorine, and more preferably an alkoxy group having 2 to 4 carbon atoms. When Y is an alkoxy group having 1 carbon atom or a halogen group excluding fluorine, the hydrolysis reaction rate is too fast, making it difficult for the outer shell of the hollow silica precursor to become dense, and shrinkage during firing increases, which tends to increase the relative dielectric constant and dielectric loss tangent of the hollow silica particles. Conversely, an alkoxy group having 5 or more carbon atoms slows the hydrolysis rate.

[0037] The silanol precursor is preferably selected from compounds represented by general formula (iii) and general formula (vii). From the viewpoint of suppressing the generation of metal-corrosive acids and from the viewpoint of hydrolysis reactivity, the silanol precursor is preferably selected from compounds represented by general formula (iii) and general formula (vii) in which Y is an alkoxy group having 2 to 4 carbon atoms, and more preferably selected from compounds represented by general formula (iii) and general formula (vii) in which Y is an ethoxy group. The silanol precursors can be used alone or in combination of two or more.

[0038] The mass ratio of the silanol precursor to the hydrophobic liquid [silanol precursor / hydrophobic liquid] is preferably 10 or more, more preferably 20 or more, even more preferably 25 or more, from the viewpoint of keeping the porosity of the hollow silica particles within an appropriate range, and is preferably 90 or less, more preferably 80 or less, even more preferably 75 or less.

[0039] Cationic Surfactant B As the cationic surfactant B, the same cationic surfactant B as the cationic surfactant A shown in step A can be used. As the cationic surfactant B, from the viewpoint of facilitating the formation of a complex with the condensed silanol and facilitating decomposition and volatilization in step C, a quaternary ammonium salt is preferred, more preferably lauryltrimethylammonium chloride (dodecyltrimethylammonium chloride), stearyltrimethylammonium chloride, and behenyltrimethylammonium chloride, and even more preferably lauryltrimethylammonium chloride. The cationic surfactant B used in this step may be the same as or different from the cationic surfactant A used in step A. Furthermore, the cationic surfactant B can be used alone or in combination of two or more types.

[0040] From the viewpoint of dispersibility of the hollow silica particle precursor, the mass ratio of the silanol precursor to the cationic surfactant B [silanol precursor / cationic surfactant B] is preferably 3 or more, more preferably 5 or more, even more preferably 6 or more, and is preferably 25 or less, more preferably 20 or less, even more preferably 18 or less.

[0041] Alkaline Substance The silanol precursor is hydrolyzed to silanol by the alkaline substance, and then undergoes dehydration condensation to form silica. Specific examples of the alkaline substance include those described in paragraph

[0014] of JP 2016-121060 A. Among these, quaternary ammonium hydroxide salts are preferred. Specific examples of quaternary ammonium hydroxide salts include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tributylmethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide (choline), tetraethanolammonium hydroxide, methyltriethanolammonium hydroxide, and dimethylbis(2-hydroxyethyl)ammonium hydroxide. From the viewpoint of densifying the outer shell of the hollow silica particle precursor, preferred are tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide, methyltriethanolammonium hydroxide, and dimethylbis(2-hydroxyethyl)ammonium hydroxide, and more preferred are tetramethylammonium hydroxide and dimethylbis(2-hydroxyethyl)ammonium hydroxide.

[0042] The mass ratio of the silanol precursor to the alkaline substance [silanol precursor / alkaline substance] is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more, from the viewpoint of making the outer shell of the hollow silica particle precursor dense, and is preferably 100 or less, more preferably 80 or less, and even more preferably 70 or less, from the viewpoint of efficiently carrying out the condensation reaction of the silanol precursor.

[0043] The alkaline substance may contain, in addition to the hydroxide salt of the quaternary ammonium, for example, an alkali metal salt, an alkaline earth metal salt, etc., but in order to reduce the content of alkali metals and alkaline earth metals in the obtained hollow silica particles, the total content of alkali metals and alkaline earth metals relative to the silanol precursor is set to be less than the content of silica (SiO ２Furthermore, the content is preferably 30 ppm by mass or less, and more preferably 10 ppm by mass or less.

[0044] By mixing an alkaline substance with a cationic surfactant B and contacting the mixture with a silanol precursor, hollow silica particles having a small maximum particle size and an appropriate coefficient of variation can be obtained. The contact of the mixture of the alkaline substance and the cationic surfactant B with the silanol precursor may be carried out by adding the mixture of the alkaline substance and the cationic surfactant B to a reaction system containing the silanol precursor, or by adding the silanol precursor to a reaction system containing the mixture of the alkaline substance and the cationic surfactant B. However, from the viewpoints of increasing the porosity and the synthesis concentration to increase productivity, it is preferable to add the mixture of the alkaline substance and the cationic surfactant B to a reaction system containing the silanol precursor.

[0045] The temperature at which step B is carried out can be appropriately adjusted depending on the type and amount of the silanol precursor and alkaline substance used, and is preferably 0° C. or higher and 100° C. or lower from the viewpoint of densifying the outer shell of the hollow silica particle precursor. For example, when orthosilicate ethyl ester or pyrosilicate ethyl ester is used as the silanol precursor, the temperature is preferably 20° C. or higher and 45° C. or lower, and when orthosilicate methyl ester or pyrosilicate methyl ester is used, the temperature is preferably 0° C. or higher and 20° C. or lower. Of these, it is preferable to use orthosilicate ethyl ester or pyrosilicate ethyl ester from the viewpoint of reaction control.

[0046] The time for carrying out step B is preferably 30 minutes or more, more preferably 1 hour or more, and even more preferably 2 hours or more from the viewpoint of densifying the outer shell of the hollow silica particle precursor, and is preferably 24 hours or less, more preferably 20 hours or less, and even more preferably 16 hours or less from the viewpoint of production efficiency.

[0047] Hollow silica particle precursor The hollow silica particle precursor is a composite silica particle having a silica-containing shell and a hydrophobic liquid inside the shell. The shell has pores formed radially toward the particle center using a cationic surfactant as a template.

[0048] Step C In step C, the hollow silica particle precursor obtained in step B is heat-treated at a temperature higher than 1000°C and not higher than 1200°C for 1 hour or longer to decompose and volatilize the cationic surfactant present in the outer shell of the hollow silica particle precursor and volatilize the hydrophobic liquid inside, and then the pores present in the outer shell are closed by firing to obtain hollow silica particles having a uniform outer shell.

[0049] The heat treatment temperature in step C is preferably 1,010°C or higher, more preferably 1,030°C or higher, and even more preferably 1,050°C or higher, from the viewpoint of reducing silanol groups on the surfaces of the hollow silica particles, and is 1,200°C or lower, preferably 1,190°C or lower, more preferably 1,180°C or lower, and even more preferably 1,160°C or lower, from the viewpoint of avoiding aggregation of the hollow silica particles.

[0050] The heat treatment time in step C is preferably 15 minutes or longer, more preferably 30 minutes or longer, and even more preferably 45 minutes or longer, from the viewpoint of reducing silanol groups on the surface of the hollow silica particles, and is preferably 3 hours or shorter, more preferably 2 hours or shorter, and even more preferably 1.5 hours or shorter, from the viewpoint of avoiding aggregation of the hollow silica particles.

[0051] [Polymer graft chain] Examples of the polymer graft chain include those containing, as monomer units, one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, fluorine-based monomers, unsaturated olefin-based monomers, conjugated diene-based monomers, and monomers having functional groups such as amino groups, hydroxy groups, and glycidyl groups. Here, the polymer constituting the polymer graft chain may be a homopolymer or a copolymer. From the viewpoint of exhibiting desired dielectric properties and improving the dispersibility of composite particles in the resin composition, a polymer composed of a styrene-based monomer and / or a conjugated diene-based monomer is preferred.

[0052] Specific examples of monomers used as raw materials for polymer graft chains include butyl methacrylate, butyl acrylate, ethyl methacrylate, ethyl acrylate, methyl methacrylate, methyl acrylate, acrylamide, acrylonitrile, 4-benzoylphenyl acrylate, benzyl methacrylate, allyl methacrylate, cyclohexyl methacrylate, N,N-dimethylmethacrylamide, dodecyl acrylate, dodecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, n-hexyl methacrylate, methacrylamide, and methacryl. Examples of suitable vinyl acrylates include acrylic acid, octadecyl acrylate, phenyl acrylate, propyl methacrylate, vinyl acetate, methoxypolyethylene glycol acrylate, methoxypolyalkylene glycol methacrylate, styrene, p-bromostyrene, 4-tert-butylstyrene, p-chlorostyrene, 4-iodostyrene, p-methoxystyrene, p-methylstyrene, α-methylstyrene, divinylbenzene (o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene), p-ethylstyrene, sodium p-styrenesulfonate, and vinylbenzyl chloride.

[0053] [Method for producing composite particles] Composite particles can be obtained by bonding polymer graft chains to the surfaces of inorganic particles. The method for bonding polymer graft chains to the particle surfaces is not particularly limited as long as it is a method that can perform graft polymerization of polymer chains, but a grafting from method in which polymer graft chains are polymerized from polymerization initiation points on the particle surfaces is preferred.

[0054] The polymerization method is not particularly limited, and examples thereof include radical polymerization, anionic polymerization, cationic polymerization, etc. Among these, living radical polymerization, living anionic polymerization, and living cationic polymerization are preferred from the viewpoint of ease of control of the molecular weight and molecular weight distribution of the polymer chain and ease of grafting various copolymers, and living radical polymerization is more preferred from the viewpoint of applicability to a wide range of monomers.

[0055] As the living radical polymerization method, atom transfer radical polymerization method (ATRP method), reversible addition-fragmentation chain transfer polymerization method (RAFT method), and nitroxide-mediated living radical polymerization method (NMP method) can be used, and from the same viewpoint, atom transfer radical polymerization method (ATRP method) is preferred.

[0056] More specifically, an example of a production method for composite particles includes the following step 2, and if necessary, the following step 1 may also be carried out. The following steps 1 and 2 can be carried out under known conditions for living radical polymerization. Step 1: A step of bonding a polymerization initiating group to the particle surface. Step 2: A step of contacting particles having polymerization initiating groups on their surface with a monomer under living radical polymerization conditions.

[0057] Step 1 is a step in which the particles are reacted with, for example, a coupling agent, thereby bonding the polymerization initiation groups of the coupling agent to the particle surface. Specifically, the particles and the coupling agent, and optionally a catalyst, a solvent, etc., are mixed to cause a reaction between them. The reaction temperature during the reaction between the particles and the coupling agent is preferably 25°C to 250°C. The amount of coupling agent used per 100 parts by mass of the particles is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more. On the other hand, from the viewpoint of suppressing reaction between the coupling agents, the amount is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less.

[0058] Step 1 preferably includes a step of introducing an amino group or a hydroxyl group onto the particle surface and a step of introducing a polymerization initiating group. In this case, it is preferable to use, as a component having the same effect as a coupling agent, a "compound having a group that bonds to the particle surface and an amino group or a hydroxyl group" or a "compound having a polymerization initiating group and a functional group that reacts with an amino group or a hydroxyl group." From the viewpoint of bonding a polymer graft chain to the particle surface, it is preferable to include a step of introducing a polymerization initiating group after the step of introducing an amino group or a hydroxyl group onto the particle surface.

[0059] The compound used in the step of introducing an amino group or a hydroxyl group onto the particle surface is a compound having a group that bonds to the particle surface and an amino group or a hydroxyl group, and from the viewpoint of easy availability, is preferably a silane compound, more preferably an aminoalkylsilane compound, and even more preferably 3-aminopropyltrimethoxysilane.

[0060] The compound used in the step of introducing a polymerization initiating group is a compound having a polymerization initiating group and a functional group reactive with an amino group or a hydroxy group, and from the viewpoint of bonding a polymer graft chain to the particle surface, is preferably a haloalkanoic acid derivative, more preferably a bromoalkanoic acid derivative, even more preferably a 2-bromo-2-methylpropionic acid derivative, and even more preferably 2-bromoisobutyl bromide.

[0061] In this way, when the step of introducing a polymerization initiating group is carried out after the step of introducing an amino group or a hydroxy group onto the particle surface, the resulting composite particles have a polymer graft chain via a structure represented by the following formula (A): (polymer graft chain)-X-(CH ２ ) ｍ -Si-(R １ ) (R ２ ) (R ３ ) Formula (A) (In formula (A), -X- is a divalent group, one of which is -(CH ２ ) ｍ The other bonded to the polymer graft chain. m is an integer of 0 to 12. R １ , R ２ and R ３ At least one of the groups is bonded to the particles by forming a metalloxane bond, and the groups not bonded to the particles are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, a hydrogen atom, a hydroxy group, or a halogen atom.

[0062] In formula (A), -X- is preferably an alkylene group having 2 to 12 carbon atoms, which may have one or more substituents (e.g., a carbonyl group, an alkyl group, or a phenyl group), and which may further be substituted with an oxygen atom or -NH-. Specific examples of suitable -X- include the following structures:

[0063]

[0064] Of these, the following structures are more preferred:

[0065]

[0066] -(CH ２ ) ｍ In the formula (A), m is an integer of 0 to 12. When m is 0, -(CH ２ ) ｍ - is a single bond, and the formula (A) is (polymer graft chain)-X-Si-(R １ ) (R ２ ) (R ３ ) When m is 1 to 12, -(CH ２ ) ｍ One or more -CH ２ - may be substituted with a phenylene group and / or -NH-.

[0067] R in formula (A) １ , R ２ and R ３ At least one of the above bonds to the particles by forming a metalloxane bond. For example, if the particles are silica, it bonds to the particles by forming a siloxane bond.

[0068] For example, when the particles originally have a polymerization initiation site or are formed as a result of surface treatment by plasma treatment or the like, they have a polymerization initiation group, so step 1 is not necessary, but when silica, mica, talc, glass filler, etc. that do not have a polymerization initiation group are used, step 1 may be performed. Note that, from the viewpoint of adjusting the graft density, a silane coupling agent that does not contain a polymerization initiation group may be added to a silane coupling agent containing a polymerization initiation group in step 1. In the step of bonding the polymerization initiation group to the particle surface in step 1, a method of dispersing the particles in a dispersion medium is preferred from the viewpoint of preventing the particles from agglomerating.

[0069] The coupling agent that can be used in step 1 is a compound used to bond the inorganic particles and the polymer graft chains. This coupling agent is not particularly limited as long as it is a compound having a polymerization initiation group and a functional group that reacts with the inorganic particle surface to form a bond. The inorganic particle surface in this case may be formed from the inorganic compound itself, or may be surface-treated. The surface treatment referred to here means modifying the inorganic particle surface with a functional group by chemical reaction, heat treatment, light irradiation, plasma irradiation, radiation irradiation, or the like.

[0070] The method for bonding a coupling agent to the surface of inorganic particles is not particularly limited, but includes, for example, a method of reacting a hydroxy group on the surface of inorganic particles with a coupling agent, or a method of reacting a functional group introduced by surface treatment of the surface of inorganic particles with a coupling agent. It is also possible to further react a coupling agent with the coupling agent bonded to the inorganic particles to link multiple coupling agents. Depending on the type of coupling agent, water or a catalyst may be used in combination.

[0071] The functional group of the coupling agent is not particularly limited, but for example, when a bond is formed by reaction with a hydroxy group on the surface of an inorganic particle, examples of the functional group include a phosphate group, a carboxy group, an acid halide group, an acid anhydride group, an isocyanate group, a glycidyl group, a chlorosilyl group, an alkoxysilyl group, a silanol group, an amino group, a phosphonium group, and a sulfonium group. Among these, from the viewpoint of the balance between reactivity, the amount of residual acid, and coloration, preferred are an isocyanate group, a chlorosilyl group, an alkoxysilyl group, and a silanol group, and more preferred are a chlorosilyl group and an alkoxysilyl group.

[0072] The polymerization initiating group of the coupling agent is not particularly limited as long as it is a functional group having polymerization initiation ability, and examples thereof include polymerization initiating groups used in nitroxide-mediated radical polymerization, atom transfer radical polymerization, and reversible addition-fragmentation chain transfer polymerization.

[0073] The polymerization initiation group in the NMP method is not particularly limited as long as it is a group to which a nitroxide group is bonded.

[0074] The polymerization initiating group in the ATRP method is typically a group containing a halogen atom. It is preferable that the bond dissociation energy of the halogen atom is low. Examples of preferred structures include a halogen atom bonded to a tertiary carbon atom; a halogen atom bonded to a carbon atom adjacent to an unsaturated carbon-carbon bond, such as a vinyl group, a vinylidene group, or a phenyl group; and a group having a halogen atom bonded directly to a heteroatom-containing conjugated group, such as a carbonyl group, a cyano group, or a sulfonyl group, or to an atom adjacent to such a heteroatom-containing conjugated group. More specifically, an organic halide group represented by the following general formula (1) and a halogenated sulfonyl group represented by the following general formula (2) are preferred.

[0075]

[0076] In the above formulas (1) and (2), R １ and R ２each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an allyl group which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, an alkylaryl group, or an alkylaryl group which may have a substituent, and Z represents a halogen atom.

[0077] The polymerization initiating group of formula (1) may have a carbonyl group, as shown in the following general formula (3): １ , R ２ and Z is R in formula (1). １ , R ２ and Z.

[0078]

[0079] Specific examples of the polymerization initiating group of formula (3) are shown in the following chemical formula.

[0080]

[0081] The polymerization initiator group in the RAFT method is not particularly limited as long as it is a general radical polymerization initiator group. A group containing a sulfur atom that functions as a RAFT agent can also be used as the polymerization initiator group. Examples of the polymerization initiator group include trithiocarbonate, dithioester, thioamide, thiocarbamate, dithiocarbamate, thiouranium, thiourea, dithiooxamide, thioketone, and trisulfide.

[0082] Specific examples of suitable coupling agents include 3-(2-bromoisobutyrylamino)propyltrimethoxysilane and 3-(2-bromoisobutyryloxy)propyltrimethoxysilane.

[0083] Step 2 is a step of contacting particles having polymerization initiating groups on their surfaces with a monomer under living radical polymerization conditions. In step 2, the particles having polymerization initiating groups on their surfaces with a monomer are preferably dispersed in a dispersion medium and polymerized, from the viewpoint of preventing aggregation of the particles, monomer, and composite particles.

[0084] The particles having polymerization initiating groups on their surfaces in step 2 are not particularly limited as long as they have a binding group that bonds the particle surface to a polymer chain. From the viewpoint of bonding a polymer graft chain to the particle surface, the polymerization initiating group is a living radical polymerization initiating group, preferably an atom transfer radical polymerization initiating group, more preferably a haloacyl group, even more preferably an α-haloacyl group, even more preferably an α-bromoacyl group, and even more preferably a 2-bromoisobutyryl group. Compounds that serve as raw materials for the binding group include compounds having a group that bonds to the particle surface and a polymerization initiating group, and compounds having a group that bonds to the particle surface or a polymerization initiating group. In the present invention, the particles having polymerization initiating groups on their surfaces in step 2 are preferably the particles obtained in step 1 above.

[0085] The amount of particles having polymerization initiation groups on the surface to be charged in step 2 is preferably 0.1 part by mass or more and preferably 1 part by mass or less, per 1 part by mass of the dispersion medium.

[0086] Examples of the monomer in step 2 include styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, fluorine-based monomers, unsaturated olefins, and conjugated diene-based monomers. In addition, monomers having specific groups in their side chains (e.g., monomers having an amino group, a hydroxy group, or a glycidyl group) can also be used. Specific examples of monomers suitable for use in step 2 include those described above in "Specific examples of monomers as raw materials for polymer graft chains."

[0087] The amount of the monomer charged in step 2 is preferably 1 part by mass or more and preferably 20 parts by mass or less per part by mass of the particles having polymerization initiation groups on the surface thereof.

[0088] A known catalyst used in living radical polymerization is used in Step 2. Preferred examples of the catalyst include copper complex catalysts (e.g., Cu(I)Br / pentamethyldiethylenetriamine, Cu(I)Br / 2,2′-bipyridyl, Cu(II)Br2 / pentamethyldiethylenetriamine, Cu(II)Br2 / 2,2′-bipyridyl).

[0089] The amount of catalyst used in step 2 is preferably 0.001 part by mass or more and preferably 0.05 part by mass or less per part by mass of the dispersion medium.

[0090] The dispersion medium used in step 2 may be a known dispersion medium used in living radical polymerization, such as anisole, acetonitrile, propionitrile, benzonitrile, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether, methanol, ethanol, propanol, isopropanol, n-butyl alcohol, tert-butyl alcohol, dimethyl sulfoxide, dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, ethylene carbonate, propylene carbonate, tetrahydrofuran, ethyl acetate, butyl acetate, pentane, hexane, cyclohexane, octane, decane, benzene, toluene, methylene chloride, chloroform, an ionic liquid, or water.

[0091] Regarding the reaction conditions in step 2, for example, the reaction temperature is preferably 40° C. or higher and 90° C. or lower, and the reaction time is preferably 1 minute or higher and 120 minutes or lower.

[0092] After polymerization, the composite particles may be optionally purified. In the purification step of the composite particles, it is preferable to disperse the composite particles in a dispersion medium in the polymer from the viewpoint of preventing aggregation of the composite particles. Although the solvent may be optionally removed, it is preferable to leave a portion of the dispersion medium and keep the polymer in a wet state. Furthermore, a method of removing the metal catalyst used in the polymerization step is preferable.

[0093] [Properties of Composite Particles] The graft density of the polymer graft chains in the composite particles is preferably 0.01 chains / nm from the viewpoint of dispersibility of the composite particles in the resin composition. ２ More preferably, 0.05 chains / nm ２ More preferably, 0.1 chains / nm ２ On the other hand, from the viewpoint of ease of grafting of polymer chains, it is preferable to use 2 chains / nm. ２ or less, more preferably 1.5 chains / nm ２ More preferably, 1 chain / nm or less ２Even more preferably 0.5 chains / nm or less ２ The graft density of the composite particles is measured by the method described in the Examples below.

[0094] From the viewpoint of dispersibility of the composite particles in the resin composition, the film thickness of the polymer graft chains in the composite particles is preferably 0.1 nm or more, more preferably 0.5 nm or more, even more preferably 1 nm or more, and still more preferably 5 nm or more. From the same viewpoint, the film thickness is preferably 1 μm or less, more preferably 500 nm or less, even more preferably 100 nm or less, still more preferably 50 nm or less, still more preferably 20 nm or less, still more preferably 15 nm or less, and still more preferably 10 nm or less.

[0095] In the case where the monomer unit in the polymer graft chain is divinylbenzene, from the same viewpoint, the film thickness is more preferably 0.1 nm or more, even more preferably 0.5 nm or more, and still more preferably 1 nm or more. Also, from the same viewpoint, the film thickness is more preferably 1 μm or less, even more preferably 500 nm or less, still more preferably 100 nm or less, still more preferably 50 nm or less, still more preferably 20 nm or less, still more preferably 15 nm or less, still more preferably 10 nm or less, and still more preferably 5 nm or less.

[0096] In the case where the monomer unit in the polymer graft chain is styrene, from the same viewpoint, the film thickness is more preferably 0.1 nm or more, even more preferably 0.5 nm or more, still more preferably 1 nm or more, and even more preferably 5 nm or more. Also, from the same viewpoint, the film thickness is more preferably 1 μm or less, even more preferably 500 nm or less, still more preferably 100 nm or less, still more preferably 50 nm or less, still more preferably 20 nm or less, and even more preferably 15 nm or less.

[0097] In the polymer graft chain, when the monomer unit is glycidyl methacrylate, from the same viewpoint, the film thickness is more preferably 0.1 nm or more, and even more preferably 0.5 nm or more, and from the same viewpoint, the film thickness is more preferably 1 μm or less, even more preferably 500 nm or less, still more preferably 100 nm or less, still more preferably 50 nm or less, still more preferably 20 nm or less, still more preferably 15 nm or less, still more preferably 10 nm or less, still more preferably 5 nm or less, and still more preferably 2 nm or less. The film thickness of the polymer graft chain is calculated by the method described in the Examples below.

[0098] The number average molecular weight of the polymer graft chains in the composite particles is preferably 1,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more, and is preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 200,000 or less.

[0099] Furthermore, from the viewpoint of reducing the shear viscosity in the resin composition, the number average molecular weight of the polymer graft chain is preferably 1,000 or more, more preferably 2,000 or more, and even more preferably 3,000 or more, and from the same viewpoint, it is preferably 50,000 or less, more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 10,000 or less, even more preferably 5,000 or less, and even more preferably 4,000 or less.

[0100] Furthermore, from the viewpoint of suppressing sedimentation of the composite particles in the resin composition, the number average molecular weight of the polymer graft chain is preferably 3,000 or more, more preferably 3,500 or more, even more preferably 4,500 or more, even more preferably 5,000 or more, even more preferably 7,000 or more, even more preferably 8,000 or more, even more preferably 10,000 or more, even more preferably 20,000 or more, even more preferably 25,000 or more, and even more preferably 27,000 or more, and from the same viewpoint, it is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 50,000 or less, even more preferably 40,000 or less, and even more preferably 35,000 or less. The number average molecular weight of the polymer graft chain is measured by the method described in the Examples below.

[0101] The content of polymer graft chains in the composite particles is preferably 0.2% by mass or more and preferably 20% by mass or less. Furthermore, from the viewpoint of reducing shear viscosity in the resin composition, the content of polymer graft chains in the composite particles is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more. From the same viewpoint, it is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass. Furthermore, from the viewpoint of suppressing sedimentation of the composite particles in the resin composition, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. From the same viewpoint, it is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. The content of polymer graft chains in the composite particles is calculated by the method described in the Examples below.

[0102] The number average molecular weight of the side chain of the polymer graft chain is preferably 10 or more, more preferably 20 or more, and even more preferably 30 or more, from the viewpoint of improving dispersibility. Furthermore, from the viewpoint of reactivity with the particle surface, the number average molecular weight of the side chain is preferably 1,000 or less, more preferably 800 or less, and even more preferably 500 or less. The number average molecular weight of the side chain of the polymer graft chain can be determined from the molecular weight of the compound used as the monomer unit. For example, when glycidyl methacrylate is used as the monomer, the formed polymer graft chain, polyglycidyl methacrylate, has a structure shown in the following formula, and the main chain and side chain in the polymer graft chain according to the present invention also have the relationship shown in the following formula.

[0103]

[0104] As described above, if the portion of polyglycidyl methacrylate outside the carbonyl bond is considered to be the side chain, the molecular weight of the side chain is 101. In other words, when the polymer graft chain is polyglycidyl methacrylate (PGMA), the number average molecular weight of the side chain is 101. Similarly, when the polymer graft chain is polyallyl methacrylate (PAMA), the number average molecular weight of the side chain is 85; when the polymer graft chain is polycyclohexyl methacrylate (PcHMA), the number average molecular weight of the side chain is 127; when the polymer graft chain is polystyrene (PSt), the number average molecular weight of the side chain is 77; and when the polymer graft chain is polydivinylbenzene (PDVB), the number average molecular weight of the side chain is 103.

[0105] The smaller the dielectric constant and dielectric loss tangent of the composite particles, the better. For example, the dielectric constant ε of the composite particles at a frequency of 10 GHz and a temperature of 25°C is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. For example, the dielectric loss tangent tanδ of the composite particles at a frequency of 10 GHz and a temperature of 25°C is preferably less than 0.01, more preferably 0.007 or less, and even more preferably 0.005 or less. Such dielectric properties can be determined by the method described in the Examples.

[0106] <Resin> The resin used in the resin composition of the present invention is a resin that satisfies at least one of the following conditions (1) to (3): (1) It is a curable resin. (2) It is a thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) It is a thermoplastic resin having a melting point, Tm, of 230°C or higher.

[0107] Examples of curable resins include polyurethane resins, urea resins, phenolic resin foams, unsaturated polyester resins, alkyd resins, melamine resins, epoxy resins, silicone resins, and modified polyphenylene ether resins. Among these, modified polyphenylene ether resins are preferred because of their excellent low dielectric properties. Specific examples of modified polyphenylene ether resins include resins obtained using modified polyphenylene ether compounds described in WO2019 / 065941 and crosslinking curing agents having carbon-carbon unsaturated double bonds in the molecule.

[0108] On the other hand, among these, epoxy resins are preferred from the viewpoint of moldability. Specific examples of epoxy resins include bisphenol-type epoxy resins and novolac-type epoxy resins. Examples of bisphenol-type epoxy resins include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol E-type epoxy resins, bisphenol M-type epoxy resins, bisphenol P-type epoxy resins, and bisphenol Z-type epoxy resins. Examples of novolac-type epoxy resins include bisphenol A-novolac-type epoxy resins, phenol novolac-type epoxy resins, and cresol novolac-type epoxy resins.

[0109] Examples of thermoplastic resins include polyolefin resins, cycloolefin resins, polystyrene resins, polyphenylene ether resins, 5-methylpentene resins, polyphenylene sulfide resins, fluorinated polyimide resins, fluorine-based resins, aromatic polyester resins, aromatic polycarbonate resins, thermotropic liquid crystal polymer resins, aromatic polysulfone resins, aromatic polyether resins, polyimide resins, polytetrafluoroethylene resins, polychlorotrifluoroethylene resins, and polyvinylidene fluoride resins.

[0110] Among these resins, epoxy resin, modified polyphenylene ether resin, fluororesin, cycloolefin resin, or polyimide resin is preferred from the viewpoint of dielectric properties.

[0111] From the viewpoint of the dielectric properties of the cured product of the resin composition, the resin used in the resin composition of the present invention preferably has a relative dielectric constant ε of 4 or less, more preferably 3.5 or less, and even more preferably 3.0 or less at a frequency of 10 GHz and a temperature of 25° C. The relative dielectric constant ε of the resin can be determined by the method described in the examples below.

[0112] Regarding the glass transition point (Tg) of the thermoplastic resin, Tg is 135 ° C. or higher, and from the viewpoint of the heat resistance of the resin molded body, it is preferably 140 ° C. or higher, more preferably 143 ° C. or higher, even more preferably 200 ° C. or higher, even more preferably 240 ° C. or higher, and even more preferably 250 ° C. or higher. On the other hand, from the viewpoint of moldability, it is preferably 450 ° C. or lower, more preferably 400 ° C. or lower, and even more preferably 350 ° C. or lower. Regarding the melting point (Tm) of the thermoplastic resin, Tm is 230 ° C. or higher, and from the viewpoint of the heat resistance of the resin molded body, it is preferably 240 ° C. or higher, more preferably 250 ° C. or higher. On the other hand, from the viewpoint of moldability, it is preferably 450 ° C. or lower, more preferably 400 ° C. or lower, and even more preferably 350 ° C. or lower. The Tg and Tm of the thermoplastic resin are determined by the method described in the examples below.

[0113] <Resin Composition> The resin composition of the present invention is a composition containing the composite particles of the present invention and a resin. The resin composition of the present invention may be a resin composition or a semi-cured product of the resin composition. The semi-cured product of the present invention refers to a resin composition that has been partially cured to the extent that it can be further cured. For example, when a resin composition is heated, the viscosity initially gradually decreases as it melts, and then curing begins, and the viscosity gradually increases. In such a case, semi-curing can refer to a state between when the viscosity starts to gradually decrease and when it is not completely cured.

[0114] The resin content in the resin composition of the present invention is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more from the viewpoint of obtaining a molded article of the resin composition, while it is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less from the viewpoint of exhibiting desired dielectric properties.

[0115] The content of the composite particles in the resin composition of the present invention is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more from the viewpoint of exhibiting desired dielectric properties, while it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less from the viewpoint of obtaining a molded article of the resin composition exhibiting desired dielectric properties.

[0116] When an epoxy resin is used as the resin in the resin composition of the present invention, it is preferable that the resin composition further contains a curing agent. The curing agent is not particularly limited as long as it is usable as a curing agent for epoxy resins, and examples thereof include amine-based curing agents, imidazole-based curing agents, and acid anhydride-based curing agents.

[0117] Specific examples of the amine curing agent include aromatic amine curing agents having one aromatic ring, such as m-phenylenediamine, 1,3-diaminotoluene, 1,4-diaminotoluene, 2,4-diaminotoluene, 3,5-diethyl-2,4-diaminotoluene, 3,5-diethyl-2,6-diaminotoluene, and 2,4-diaminoanisole; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-methylenebis(2-ethylaniline), 3,3'-diethyl-4,4'-diaminodiphenylmethane, and 3,4'-diaminoanisole; aromatic amine curing agents having two aromatic rings, such as 3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane and 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane; hydrolysis condensates of aromatic amine curing agents; aromatic amine curing agents having a polyether structure, such as polytetramethylene oxide di-p-aminobenzoate and polytetramethylene oxide di-para-aminobenzoate; condensates of aromatic diamines and epichlorohydrin; and reaction products of aromatic diamines and styrene.

[0118] When a curing agent is used, the blending amount is not particularly limited and may be a known blending amount. The epoxy resin and the curing agent may be blended in one container as a so-called one-component composition, or may be blended in different containers as a two-component composition.

[0119] A preferred embodiment of the resin composition of the present invention is the above-described resin composition, wherein the polymer graft chain contains 10 mass % or more of one or more monomer units selected from the group consisting of styrene, divinylbenzene, glycidyl methacrylate, allyl methacrylate, and cyclohexyl methacrylate. From the viewpoint of dispersibility of the composite particles, such a resin composition is a preferred embodiment of the resin composition of the present invention.

[0120] From the viewpoint of dispersibility of the composite particles and reactivity with the resin, the monomer unit in the polymer graft chain is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 100% by mass.

[0121] Here, the content of the monomer unit in the polymer graft chain is determined as follows: The content of the above-mentioned monomer in the polymerization solution is measured by NMR. The difference between the content of the monomer before polymerization and the content of the monomer after polymerization is the amount of monomer used in the polymerization reaction. Assuming that all of the amount used is formed as a polymer graft chain, the amount of monomer used in the polymerization reaction is calculated as the content of the monomer unit in the polymer graft chain.

[0122] Another preferred embodiment of the resin composition of the present invention is the above-described resin composition, wherein the resin is an epoxy resin and the polymer graft chain contains 10 mass % or more of a monomer unit having an SP value of 10 to 12. From the viewpoints of dispersibility of the composite particles and reduction in viscosity, such a resin composition is another preferred embodiment of the resin composition of the present invention.

[0123] In the above aspect, from the viewpoint of dispersibility of the composite particles, the monomer unit in the polymer graft chain is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 100% by mass.

[0124] Yet another preferred embodiment of the resin composition of the present invention is the above-described resin composition, wherein the resin is a modified polyphenylene ether resin, and the polymer graft chain contains 10 mass % or more of a monomer unit having an SP value of 8 to 10. From the viewpoint of dispersibility of the composite particles, such a resin composition is another preferred embodiment of the resin composition of the present invention.

[0125] In the above aspect, from the viewpoints of dispersibility of the composite particles and reactivity with the resin, the monomer unit in the polymer graft chain is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, still more preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 100% by mass.

[0126] The SP value in this specification refers to the solubility parameter calculated by the Fedors method (unit: (cal / cm 3 ) 1 / 2 ) and are described in, for example, references such as "SP Value Basics, Applications and Calculation Methods" (Johokikansha, 2005) and Polymer Handbook Third Edition (A Wiley-Interscience publication, 1989).

[0127] The main monomers used as the monomer units and their SP values ​​are as follows: styrene (SP value: 9.0), divinylbenzene (SP value: 9.3), glycidyl methacrylate (SP value: 10.7), and allyl methacrylate (SP value: 9.7).

[0128] [Method for Producing Resin Composition] The resin composition of the present invention can be produced by a production method including a step of mixing or kneading the composite particles and a resin. For example, a production method including a step of melt-kneading the resin and the composite particles can be used. For melt-kneading, a known kneader such as an internal kneader, a single-screw or twin-screw extruder, or an open-roll kneader can be used. After melt-kneading, the melt-kneaded mixture may be dried or cooled according to a known method. Alternatively, the raw materials may be uniformly mixed in advance using a Henschel mixer, a super mixer, or the like, before being subjected to melt-kneading. The melt-kneading temperature and melt-kneading time are not necessarily set depending on the type of raw materials used, but are preferably 170 to 240°C and 15 to 900 seconds.

[0129] As an example of a production method, a method of kneading the components without thermal melting will be described below. First, the components that are soluble in organic solvents are added to the organic solvent and dissolved. Heat may be applied if necessary. Then, components that are insoluble in organic solvents are added as needed, and the mixture is dispersed using a ball mill, bead mill, planetary mixer, roll mill, rotary mixer, planetary mixer, high-pressure homogenizer, ultrasonic homogenizer, or the like until a predetermined dispersion state is achieved, thereby preparing a varnish-like composition.

[0130] In addition, it is preferable to disperse components that are not soluble in organic solvents in advance in an organic solvent. Methods for pre-dispersing include a ball mill, a bead mill, a planetary mixer, a roll mill, a rotary mixer, a planetary mixer, a high-pressure homogenizer, and an ultrasonic homogenizer. The organic solvent used here is not particularly limited as long as it dissolves the modified polyphenylene ether compound and the crosslinked curing agent and does not inhibit the curing reaction. Specific examples include toluene and methyl ethyl ketone (MEK).

[0131] [Dielectric Properties of Resin Composition] The smaller the relative dielectric constant and dielectric loss tangent of the cured product of the resin composition of the present invention, the better. For example, the relative dielectric constant ε of the cured product at a frequency of 10 GHz and a temperature of 25°C is preferably 2.8 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. For example, the dielectric loss tangent tanδ of the cured product at a frequency of 10 GHz and a temperature of 25°C is preferably 0.008 or less, more preferably 0.007 or less, and even more preferably 0.006 or less. Such dielectric properties can be determined by the method described in the examples.

[0132] Since the resin composition of the present invention can achieve such dielectric properties, the resin composition of the present invention can be used as a low dielectric resin composition, a resin composition for low dielectric materials, a resin composition for copper-clad laminates, a resin composition for primary mounting underfill materials, or a resin composition for interlayer insulating materials. Therefore, the low dielectric resin composition or the resin composition for low dielectric materials of the present invention is a composition containing the above-mentioned composite particles and a resin.

[0133] The resin composition, low dielectric resin composition, resin composition for low dielectric material, resin composition for copper-clad laminate, resin composition for primary mounting underfill material or resin composition for interlayer insulating material of the present invention may contain, as necessary, other components in addition to those described above, such as a flame retardant, an initiator, an antifoaming agent, an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a pigment or dye, a lubricant, an inorganic filler, a crosslinking agent, a toughness improver, an impact absorber or the like.

[0134] The applications of the resin composition, low dielectric resin composition, resin composition for low dielectric material, resin composition for copper-clad laminate, resin composition for primary mounting underfill material, or resin composition for interlayer insulating material of the present invention are not particularly limited, and they can be used in a wide range of applications requiring a resin composition, such as adhesive films, sheet-like laminate materials such as prepregs, solder resists, underfill materials, die bonding materials, semiconductor encapsulants, hole filling resins, component embedding resins, circuit boards (laminate boards, multilayer printed wiring boards, etc.), and semiconductor devices.

[0135] The present invention also includes the following aspects.

[0136] <1> A resin composition containing composite particles having polymer graft chains on the surfaces of inorganic particles, and a resin, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin having a melting point, Tm, of 230°C or higher.

[0137] <2> A resin composition containing composite particles having polymer graft chains on the surfaces of inorganic particles, and a resin, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, the polymer graft chains contain 10 mass% or more of one or more monomer units selected from the group consisting of styrene, divinylbenzene, glycidyl methacrylate, allyl methacrylate, and cyclohexyl methacrylate, and the resin satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin having a melting point, Tm, of 230°C or higher. <3> The resin composition according to <1> or <2>, wherein the resin is an epoxy resin, and the polymer graft chains contain 50 mass% or more of monomer units having an SP value of 10 or higher and 12 or lower. <4> The resin composition according to <1> or <2>, wherein the resin is a modified polyphenylene ether resin, and the polymer graft chain contains 50% by mass or more of monomer units having an SP value of 8 or more and 10 or less. <5> The resin composition according to any one of <1> to <4>, wherein the number average molecular weight of a side chain of the polymer graft chain is 10 or more and 1,000 or less. <6> The resin composition according to any one of <1> to <5>, wherein the resin is an epoxy resin, a modified polyphenylene ether resin, a fluororesin, a cycloolefin resin, or a polyimide resin. <7> The graft density of the polymer graft chain is 0.01 chains / nm ２The resin composition according to any one of <1> to <6>, wherein the polymer graft chain contains, as a monomer unit, one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, fluorine-based monomers, unsaturated olefin-based monomers, conjugated diene-based monomers, and monomers having an amino group, a hydroxy group, or a glycidyl group. <9> The resin composition according to any one of <1> to <8>, wherein the composite particles have a dielectric loss tangent tanδ of less than 0.01 at a frequency of 10 GHz and a temperature of 25°C. <10> The resin composition according to any one of <1> to <9>, wherein the inorganic particles are silica, and the total content of alkali metals and alkaline earth metals relative to the content of silica in the inorganic particles is 50 ppm by mass or less.

[0138] <11> The resin composition according to any one of <1> to <10>, wherein the composite particles have the polymer graft chain via a structure represented by the following formula (A): (polymer graft chain)-X-(CH ２ ) ｍ -Si-(R １ ) (R ２ ) (R ３ ) Formula (A) (In formula (A), -X- is a divalent group, one of which is -(CH ２ ) ｍ The other bonded to the polymer graft chain. m is an integer of 0 to 12. R １ , R ２ and R ３ at least one of the above is bonded to the particle by forming a metalloxane bond, and those not bonded to the particle are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, a hydrogen atom, a hydroxy group, or a halogen atom.) <12> In the polymer graft chain, the monomer unit is glycidyl methacrylate, the content of the polymer graft chain in the composite particle is 0.5% by mass or more and 1% by mass or less, the number average molecular weight is 3000 or more and 4000 or less, and the graft density is 0.1 chains / nm ２0.5 chains / nm or more ２ The resin composition according to any one of <1> to <11>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1100 nm, and the resin is an epoxy resin. <13> The resin composition according to any one of <1> to <11>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1100 nm, and the resin is an epoxy resin. <13> The polymer graft chains are formed by mixing a monomer unit of styrene with a polymer graft chain content of 4 mass % to 8 mass %, a number average molecular weight of 20,000 to 40,000, and a graft density of 0.1 chains / nm ２ 0.5 chains / nm or more ２ The resin composition according to any one of <1> to <11>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1100 nm, and the resin is a modified polyphenylene ether resin. <14> The resin composition according to any one of <1> to <11>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1100 nm, and the resin is a modified polyphenylene ether resin. <14> The polymer graft chains are each a monomer unit of divinylbenzene, and the content of the polymer graft chains in the composite particles is 1 mass % to 3 mass %, and the number average molecular weight is 5,000 to 20,000, and the graft density is 0.1 chains / nm ２ 0.5 chains / nm or more ２The resin composition according to any one of <1> to <11>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1100 nm, and the resin is a modified polyphenylene ether resin. <15> The resin composition according to any one of <1> to <14>, which is a low dielectric resin composition. <16> The resin composition according to any one of <1> to <14>, which is a resin composition for a low dielectric material. <17> The resin composition according to any one of <1> to <14>, which is a resin composition for a copper-clad laminate, an interlayer insulating film, or a primary mounting underfill material. <18> The resin composition according to any one of <1> to <14>, which is a resin composition for a primary mounting underfill material. <19> In the polymer graft chain, the monomer unit is glycidyl methacrylate, the content of the polymer graft chain in the composite particle is 0.5% by mass or more and 1% by mass or less, the number average molecular weight is 3000 or more and 4000 or less, and the graft density is 0.1 chains / nm ２ 0.5 chains / nm or more ２ <20> The resin composition for primary mounting underfill material according to any one of <1> to <14>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1100 nm, and the resin is an epoxy resin, <21> The polymer graft chains have a monomer unit of styrene, a content of the polymer graft chains in the composite particle is 4 mass % to 8 mass %, a number average molecular weight of 20,000 to 40,000, and a graft density of 0.1 chains / nm ２ 0.5 chains / nm or more ２the resin composition for a copper-clad laminate according to any one of <1> to <14>, wherein the film thickness is 5 nm or more and 15 nm or less, the number average molecular weight of the side chains is 50 or more and 100 or less, the inorganic particles are solid silica, and the average particle diameter is 700 nm or more and 1100 nm or less, and the resin is a modified polyphenylene ether resin.

[0139] <21> In the polymer graft chain, the monomer unit is divinylbenzene, the content of the polymer graft chain in the composite particle is 1% by mass or more and 3% by mass or less, the number average molecular weight is 5,000 or more and 20,000 or less, and the graft density is 0.1 chains / nm ２ 0.5 chains / nm or more ２the resin composition for a copper-clad laminate according to any one of <1> to <14>, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm to 1,100 nm, and the resin is a modified polyphenylene ether resin. <22> A method for producing a resin composition, comprising a step of mixing or kneading composite particles having polymer graft chains on their surfaces with a resin, wherein the inorganic particles have an average particle diameter of more than 200 nm and 3,000 nm or less, and the resin satisfies at least one of the following conditions (1) to (3): (1) the resin is a curable resin; (2) the resin is a thermoplastic resin having a glass transition point, Tg, of 135°C or higher; and (3) the resin is a thermoplastic resin having a melting point, Tm, of 230°C or higher. <23> Use of composite particles having polymer graft chains on the surfaces of inorganic particles as a resin composition, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin having a melting point, Tm, of 230°C or higher. <24> A method for producing the resin composition according to <22>, comprising the following steps: (Step 1) A step of producing composite particles. (Step 1-a) A step of bonding a polymerization initiating group to the surface of solid silica (Step 1-a-1) A step of introducing an amino group onto the surface of solid silica (Step 1-a-2) A step of introducing a 2-bromoisobutyryl group, which is a polymerization initiating group, onto the surface of the particles obtained in Step 1-a-1 (Step 1-b) A step of contacting the particles obtained in Step 1-a-2 with glycidyl methacrylate under living radical polymerization conditions (Step 2) A step of kneading a dispersion containing the composite particles obtained in Step 1-b with an epoxy resin. <25> A method for producing a resin composition according to <22> above, comprising the following steps: (Step 1) A step of producing composite particles.(Step 1-a) A step of bonding a polymerization initiator group to the surface of solid silica; (Step 1-a-1) A step of introducing an amino group onto the surface of solid silica; (Step 1-a-2) A step of introducing a 2-bromoisobutyryl group, which is a polymerization initiator group, onto the surface of the particles obtained in Step 1-a-1; (Step 1-b) A step of contacting the particles obtained in Step 1-a-2 with glycidyl methacrylate under living radical polymerization conditions; (Step 2) A step of drying and crushing a dispersion containing the composite particles obtained in Step 1-b; (Step 3) A step of kneading the powder obtained in Step 2 with an epoxy resin. <26> A method for producing a resin composition for a primary mounting underfill material, comprising the following steps: (Step 1) A step of producing composite particles. (Step 1-a) A step of bonding a polymerization initiating group to the surface of solid silica; (Step 1-a-1) A step of introducing an amino group onto the surface of solid silica; (Step 1-a-2) A step of introducing a 2-bromoisobutyryl group, which is a polymerization initiating group, onto the surface of the particles obtained in Step 1-a-1; (Step 1-b) A step of contacting the particles obtained in Step 1-a-2 with glycidyl methacrylate under living radical polymerization conditions; and (Step 2) A step of kneading a dispersion containing the composite particles obtained in Step 1-b with an epoxy resin. <27> A method for producing a resin composition for a primary mounting underfill material, comprising the following steps: (Step 1) A step of producing composite particles. (Step 1-a) A step of bonding a polymerization initiator group to the surface of solid silica, (Step 1-a-1) A step of introducing an amino group onto the surface of the solid silica, (Step 1-a-2) A step of introducing a 2-bromoisobutyryl group, which is a polymerization initiator group, onto the surface of the particles obtained in Step 1-a-1, (Step 1-b) A step of contacting the particles obtained in Step 1-a-2 with glycidyl methacrylate under living radical polymerization conditions, (Step 2) A step of drying and crushing a dispersion containing the composite particles obtained in Step 1-b, and (Step 3) A step of kneading the powder obtained in Step 2 with an epoxy resin. <28> Use of the resin composition according to any one of <1> to <14> above for a copper-clad laminate, an interlayer insulating film, or a primary mounting underfill material.<29> In the polymer graft chain, the monomer unit is glycidyl methacrylate, the content of the polymer graft chain in the composite particle is 0.5% by mass or more and 1% by mass or less, the number average molecular weight is 3000 or more and 4000 or less, and the graft density is 0.1 chains / nm. ２ 0.5 chains / nm or more ２ <30> Use of the resin composition according to <28> as a primary mounting underfill material, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm or more and 1100 nm or less, the film thickness is 0.5 nm or more and 2 nm or less, the number average molecular weight of the side chains is 80 or more and 120 or less, the inorganic particles are solid silica and have an average particle diameter of 700 nm or more and 1100 nm or less, and the resin is an epoxy resin. <31> Use of the resin composition according to <28> as a primary mounting underfill material, wherein the inorganic particles are solid silica and have an average particle diameter of 700 nm or more and 1100 nm or less, the polymer graft chains are styrene, the content of the polymer graft chains in the composite particles is 4 mass% or more and 8 mass% or less, the number average molecular weight is 20,000 or more and 40,000 or less, and the graft density is 0.1 chains / nm ２ 0.5 chains / nm or more ２ or less, the film thickness is 5 nm or more and 15 nm or less, the number average molecular weight of the side chain is 50 to 100, the inorganic particles are solid silica, the average particle diameter is 700 nm or more and 1100 nm or less, and the resin is a modified polyphenylene ether resin. Use of the resin composition according to <28> as a copper-clad laminate.

[0140] <31> In the polymer graft chain, the monomer unit is divinylbenzene, the content of the polymer graft chain in the composite particle is 1% by mass or more and 3% by mass or less, the number average molecular weight is 5,000 or more and 20,000 or less, and the graft density is 0.1 chains / nm ２ 0.5 chains / nm or more ２or less, the film thickness is 1 nm or more and 5 nm or less, the number average molecular weight of the side chain is 80 to 150, the inorganic particles are solid silica, the average particle diameter is 700 nm or more and 1100 nm or less, and the resin is a modified polyphenylene ether resin. Use of the resin composition according to <28> as a copper-clad laminate.

[0141] The present invention will be specifically explained below by showing examples, but the present invention is not limited to the following examples.

[0142] [Melting Point (Tm) and Glass Transition Temperature (Tg) of Thermoplastic Resin] Using a differential scanning calorimeter (TA Instruments Japan, Q100), 0.02 g of a sample was weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, and the calorific value was measured. The temperature of the peak with the largest peak area among the observed endothermic peaks was taken as the maximum endothermic peak temperature. When the resin was a crystalline resin, the peak temperature was taken as the melting point. When the resin was an amorphous resin, if a peak was observed, the temperature of the peak was taken as the glass transition temperature. When no peak was observed but a step was observed, the temperature at the intersection of the tangent showing the maximum slope of the curve at the step and an extension of the baseline on the low-temperature side of the step was taken as the glass transition temperature.

[0143] [Porosity of inorganic particles] The porosity (volume %) of inorganic particles was calculated according to the following formula using the density measured using a true density measuring device with nitrogen as the measurement gas. The true density measuring device used was an ULTRAPYCNOMETER 1000 manufactured by QUANTACHROME. The material density of silica was 2.2 (g / cm ３ For particles other than silica, the material density value of the material that constitutes the particle was used. Porosity (volume %) of inorganic particles = [1 - (measured density / material density of silica particles)] x 100

[0144] [Average particle size of inorganic particles] The average particle size of inorganic particles was measured by the Coulter counter method using a Multisizer 3 (manufactured by Beckman Coulter, Inc., using a 20 μm aperture tube). The average particle size and standard deviation of particle sizes were determined on a volume basis, and the coefficient of variation was calculated using the following formula: Coefficient of variation (%) = [(standard deviation of particle sizes) / (average particle size)] × 100. The maximum particle size was defined as the particle size at 99% of the cumulative frequency distribution on a volume basis.

[0145] [Specific Surface Area of ​​Inorganic Particles] The specific surface area of ​​inorganic particles was measured using the BET specific surface area. Specifically, the BET specific surface area of ​​the particles was measured using a specific surface area measuring device (Shimadzu Corporation, product name "Flowsorb III 2305"). The sample was pretreated by heating at 200°C for 15 minutes.

[0146] [Metal Content of Inorganic Particles] The metal content of inorganic particles was measured as the total content of alkali metals and alkaline earth metals in the particles as follows. 100 mg of particles were placed in a platinum crucible, and 3 mL of concentrated nitric acid, 1 mL of concentrated hydrofluoric acid, and 1 mL of concentrated hydrochloric acid were added thereto, and the mixture was heated to evaporate to dryness. The residue in the crucible was then diluted with hydrochloric acid and measured using an inductively coupled plasma mass spectrometer (Agilent Technologies, product name: Agilent 8900).

[0147] [Content of polymer graft chains in composite particles] The content of polymer graft chains in the composite particles was determined by the weight loss rate determined by the thermal weight loss measurement shown below. Then, the content (mass%) of polymer graft chains in the composite particles was calculated using the following formula: Content (mass%) of polymer graft chains = "Weight loss rate (mass%) when heating from 40°C to 500°C at a rate of 10°C / min"

[0148] [Graft Density of Polymer Graft Chains in Composite Particles] The graft density of polymer graft chains in composite particles (chains / nm ２ ) is the mass per unit area of ​​the grafted chains bonded to the surface of the composite particle (g / nm ２ The graft density (chains / nm) was calculated by the following formula: ２) = [mass of grafted chains per unit area (g / nm ２ ) / number average molecular weight of grafted chains × (Avogadro's number)

[0149] Here, the mass of the grafted chains was determined by thermal gravitational loss (TG) measurements. Specifically, the composite particles to be measured were heated in air from 40°C to 500°C at a rate of 10°C / min, and the weight loss rate was measured. Furthermore, the "mass of grafted chains per unit area" was calculated from the specific surface area of ​​the inorganic particles that were the raw material for the composite particles to be measured. The number-average molecular weight of the grafted chains was determined by gel permeation chromatography (GPC) as shown below.

[0150] [Number-Average Molecular Weight of Polymer Graft Chains in Composite Particles] The number-average molecular weight of the polymer graft chains in the composite particles was determined by extracting only the polymer graft chains from the composite particles. Specifically, 200 mg of composite particles were stirred for 12 hours in 2 mL of a tetrabutylammonium fluoride solution (approximately 1 mol / L) in tetrahydrofuran (Tokyo Chemical Industry Co., Ltd.) to detach the polymer graft chains from the composite particles. The resulting tetrahydrofuran solution containing the dissolved polymer graft chains was reprecipitated with a large amount of methanol, and the solvent was removed and dried to isolate the detached polymer graft chains. This was dissolved in chloroform and used as the solution for the GPC measurement described below. The number-average molecular weight was measured by gel permeation chromatography (GPC) using a TSKgel GMHHR-H + GMHHR-H (cation) (Tosoh Corporation) column, chloroform as the solvent, at a flow rate of 1.0 mL / min and a column temperature of 40°C, using polystyrene as a molecular weight standard.

[0151] [Film Thickness of Polymer Graft Chains in Composite Particles] The film thickness was calculated using the following formula. The polymer density in the formula was defined as the polymer density of the polymer graft chains that were not bonded to the composite particles and were simultaneously produced in the process of producing the composite particles. The polymer density was measured by a pycnometer method in accordance with JIS K 7112.

[0152]

[0153] Production Example 1 [Production of Silica Microparticles] 388.6 g of ion-exchanged water, 200 g of dodecane (Kishida Chemical Co., Ltd.: primary n-dodecane), and 11.4 g of QUARTAMINE 86W (Kao Corporation: containing 28% by mass of stearyl trimethyl ammonium chloride) were mixed and stirred to obtain Emulsion A. The volume average particle size of the particles in the obtained Emulsion A was 0.9 μm. A reaction vessel was charged with 13,192.5 g of ion-exchanged water, 138.1 g of Emulsion A, 125.6 g of QUARTAMINE 24P (Kao Corporation: containing 27.5% by mass of lauryl trimethyl ammonium chloride), and 3,120.8 g of ethyl orthosilicate (Wacker Asahi Kasei Silicones: TEOS999), and the mixture was heated to 40° C. with stirring and then stirred for 10 minutes to obtain Preparation Solution B.

[0154] Next, 221.5 g of AH212-CS (manufactured by Yokkaichi Synthetic Co., Ltd.: containing 50% by mass of dimethylbis(2-hydroxyethyl)ammonium hydroxide) and 711.6 g of Courtamine 24P were uniformly mixed to obtain Preparation Solution C. The entire amount of Preparation Solution C was added to the entire amount of Preparation Solution B at a constant rate, and then the mixture was stirred at 40°C for 3 hours to obtain a cloudy white liquid D.

[0155] The resulting cloudy liquid D was then filtered using a No. 5C filter paper (manufactured by Advantec Toyo Co., Ltd.), washed with water, and dried at 110°C to obtain white hollow silica particle precursors. The resulting hollow silica particle precursors were calcined at 1100°C for 1 hour to obtain hollow silica particles (average particle size 1.9 µm, coefficient of variation 27%, BET specific surface area 9.6 m). ２ The hollow silica particles were designated as silica fine particles 1.

[0156] Production Example 2 [Production of Silica Microparticles] 91 g of Catiogen TML (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.: containing 30 mass % dodecyltrimethylammonium chloride), 17 g of a 25% aqueous solution of tetramethylammonium hydroxide (manufactured by Seichem Asia Co., Ltd.: pH 14), and 20 g of hexane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) were added to 2,000 g of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade), and the mixture was stirred to prepare a solution phase containing a hydrophobic organic substance and a hydrophilic organic solvent.

[0157] The resulting solution phase was simultaneously poured out and mixed in a ratio of 1 part by volume to 1 part by volume of ion-exchanged water to obtain an emulsion.

[0158] To the resulting emulsion, 1500 g of ion-exchanged water was added. To the resulting emulsion after the addition of ion-exchanged water, 18 g of orthosilicate methyl ester (tetramethoxysilane) (manufactured by Tama Chemicals Co., Ltd.) was added and stirred at 25°C for 10 minutes to obtain a cloudy solution. The resulting cloudy solution was filtered using 5C filter paper (manufactured by Advantec Toyo Co., Ltd.) and dried at 100°C to obtain composite silica particles. The resulting composite silica particles were calcined at 1000°C for 38 hours to obtain hollow silica particles (average particle size 1.9 μm, coefficient of variation 17%, BET specific surface area 8.0 m). ２ The hollow silica particles were designated as silica fine particles 2.

[0159] Preparation Example 1 [Preparation of Composite Particle 1] Step a) Step of Bonding Polymerization Initiator Groups to the Particle Surface Step a-1) Introduction of Amino Groups onto the Surface of Silica Particles 40 g of the silica particles obtained in Preparation Example 1 above and 2 g of 3-aminopropyltrimethoxysilane (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to 200 mL of ethanol. The mixture was stirred at room temperature (approximately 25°C, the same applies below) for 12 hours. The mixture was then washed with ethanol, and the silica particles were recovered using a centrifuge, followed by heating at 110°C for 1 hour to obtain amino-group-introduced silica particles.

[0160] Step a-2) Introduction of polymerization initiator groups onto the surface of amino group-introduced silica microparticles Into a 500 mL eggplant-shaped flask were placed 40 g of the above amino group-introduced silica microparticles, 200 mL of anhydrous THF, 1 mL of anhydrous triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1 mL of 2-bromoisobutyl bromide (BIBB) (manufactured by Tokyo Chemical Industry Co., Ltd.), and the mixture was stirred at room temperature for 2 hours. After that, the mixture was washed with THF and anisole, and the polymerization initiator group-introduced silica microparticles into which 2-bromoisobutyryl groups had been introduced as polymerization initiator groups were recovered by centrifugation and then stored as anisole-wet polymerization initiator group-introduced silica microparticles.

[0161] Step b) A step of contacting particles having polymerization initiation groups on the surface with a monomer under living radical polymerization conditions. In a 500 mL separable flask, an anisole wet mixture containing 12 g of the silica microparticles having polymerization initiation groups prepared above, 60 g of anisole, and 180 g of styrene as a monomer were placed, thoroughly stirred, and then subjected to reduced pressure nitrogen substitution. Thereafter, the temperature was raised to 90 ° C., and an acetonitrile solution prepared by previously stirring 860 mg of Cu (I) Br (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured, and polymerization was initiated. Then, the mixture was stirred for 30 minutes, followed by ice water cooling and air bubbling, and an excess of methanol was added to quench the reaction.

[0162] Thereafter, washing with methanol and removal of the solution by filtration were repeated three times, followed by washing with toluene and removal of the solution by filtration once to obtain polystyrene-grafted silica microparticles (i.e., composite particles 1). Further, the obtained solid was added with toluene without being dried, and stored as a toluene solution.

[0163] The content of the polymer graft chains in the obtained composite particle 1 was 2.7% by mass, the number average molecular weight of the polymer graft chains was 8,000, and the graft density of the polymer graft chains was 0.19 chains / nm ２ The film thickness of the polymer graft chain was 2 nm, and the content of the monomer unit (styrene) in the polymer graft chain was 100% by mass. A schematic diagram of the structure of the obtained composite particle 1 is shown in FIG.

[0164] Preparation Example 2 [Preparation of Composite Particles 2] Step b) A step of contacting particles having polymerization initiating groups on their surfaces with a monomer under living radical polymerization conditions. A 500 mL separable flask was charged with an anisole wet solution containing 12 g of silica microparticles having polymerization initiating groups prepared in step a) of Preparation Example 1, 60 g of anisole, and 180 g of divinylbenzene as a monomer, and the flask was thoroughly stirred and then subjected to reduced pressure nitrogen substitution. The flask was then heated to 90 ° C., and an acetonitrile solution prepared in advance by stirring 860 mg of Cu(I)Br (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was added to initiate polymerization.

[0165] Thereafter, washing with methanol and removal of the solution by filtration were repeated three times, and then washing with toluene and removal of the solution by filtration were performed once to obtain silica microparticles grafted with polydivinylbenzene (i.e., composite particles 2). Further, toluene was added to the obtained solid without drying, and the solid was stored as a toluene solution.

[0166] The content of the polymer graft chains in the obtained composite particle 2 was 2.1% by mass, the number average molecular weight of the polymer graft chains was 6,300, and the graft density of the polymer graft chains was 0.19 chains / nm ２ The film thickness of the polymer graft chains was 2 nm, and the content of the monomer unit (divinylbenzene) in the polymer graft chains was 100% by mass.

[0167] Preparation Example 3 [Preparation of Composite Particle 3] Step b) A step of contacting particles having polymerization initiating groups on the surface with a monomer under living radical polymerization conditions. A 500 mL separable flask was charged with an anisole wet solution containing 12 g of the silica microparticles having polymerization initiating groups prepared in step a) of Preparation Example 1 above, and 240 g of styrene as a monomer, and thoroughly stirred, followed by decompression and nitrogen substitution. Thereafter, the temperature was raised to 90 ° C., and an acetonitrile solution prepared in advance by stirring 860 mg of Cu(I)Br (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured, and polymerization was initiated.

[0168] Thereafter, washing with methanol and removal of the solution by filtration were repeated three times, and then washing with toluene and removal of the solution by filtration were performed once to obtain polystyrene-grafted silica microparticles (i.e., composite particles 3). Further, toluene was added to the obtained solid without drying, and the solid was stored as a toluene solution.

[0169] The content of the polymer graft chains in the obtained composite particle 3 was 5.9% by mass, the number average molecular weight of the polymer graft chains was 24,000, and the graft density of the polymer graft chains was 0.14 chains / nm ２ The film thickness of the polymer graft chains was 5 nm, and the content of the monomer unit (styrene) in the polymer graft chains was 100% by mass.

[0170] Preparation Example 4 [Preparation of Composite Particles 4] Polystyrene-grafted silica microparticles (i.e., Composite Particles 4) were prepared in the same manner as in Preparation Example 1, except that 40 g of the silica microparticles obtained in Preparation Example 2 above were used as the silica microparticles.

[0171] The content of the polymer graft chains in the obtained composite particle 4 was 2.7% by mass, the number average molecular weight of the polymer graft chains was 8,000, and the graft density of the polymer graft chains was 0.19 chains / nm ２ The film thickness of the polymer graft chains was 2 nm, and the content of the monomer unit (styrene) in the polymer graft chains was 100% by mass.

[0172] Preparation Example 5 [Preparation of Composite Particles 5] Steps a) and b) were carried out in the same manner as in Preparation Example 1, except that silica fine particles (Admafine SO-C2, manufactured by Admatechs Co., Ltd., average particle size 900 nm) were used instead of the silica fine particles obtained in the above-mentioned Production Example 1, to obtain polystyrene-grafted silica fine particles (i.e., Composite Particles 5). Further, toluene was added to the obtained solid without drying, and the resulting solution was stored as a toluene solution.

[0173] The content of the polymer graft chains in the obtained composite particle 5 was 6.1% by mass, the number average molecular weight of the polymer graft chains was 30,000, and the graft density of the polymer graft chains was 0.24 chains / nm ２The film thickness of the polymer graft chains was 10 nm, and the content of the monomer unit (styrene) in the polymer graft chains was 100% by mass.

[0174] Preparation Example 6 [Preparation of Composite Particles 6] Polydivinylbenzene-grafted silica microparticles (i.e., Composite Particles 6) were obtained in the same manner as in Preparation Example 2, except that silica microparticles (Admafine SO-C2, manufactured by Admatechs Co., Ltd., average particle size 900 nm) were used instead of the silica microparticles having polymerization initiating groups prepared in step a) of Preparation Example 1 above. Toluene was then added to the obtained solid without drying, and the resulting solution was stored as a toluene solution.

[0175] The content of the polymer graft chains in the obtained composite particle 6 was 2.0% by mass, the number average molecular weight of the polymer graft chains was 10,000, and the graft density of the polymer graft chains was 0.23 chains / nm ２ The film thickness of the polymer graft chains was 3 nm, and the content of the monomer unit (divinylbenzene) in the polymer graft chains was 100% by mass.

[0176] Preparation Example 7 [Preparation of Composite Particles 7] (Introduction of vinyl groups onto the surface of silica microparticles) 40 g of the silica microparticles obtained in Preparation Example 1 above and 2 g of vinyltrimethoxysilane (Kanto Chemical Co., Ltd.) were added to 200 mL of ethanol. The mixture was stirred at room temperature for 12 hours. After washing with ethanol, the silica microparticles were recovered using a centrifuge and then heated at 110°C for 1 hour to obtain silica microparticles with vinyl groups introduced therein (i.e., Composite Particles 7). Composite Particles 7 were not particles having polymer graft chains.

[0177] Preparation Example 8 [Preparation of Composite Particles 8] Steps a) and b) were carried out in the same manner as in Preparation Example 1, except that silica microparticles (Silfil NSS-3N, manufactured by Tokuyama Corporation, average particle size 120 nm) were used instead of the silica microparticles obtained in Production Example 1, to obtain polystyrene-grafted silica microparticles (i.e., Composite Particles 8). Toluene was added to the obtained solid without drying, and the resulting solution was stored as a toluene solution.

[0178] The content of the polymer graft chains in the obtained composite particle 8 was 15.8% by mass, the number average molecular weight of the polymer graft chains was 20,000, and the graft density of the polymer graft chains was 0.19 chains / nm ２ The thickness of the polymer graft chain was 5 nm, and the content of the monomer unit (styrene) in the polymer graft chain was 100 mass %. Composite particle 8 was a particle having a polymer graft chain, and the average particle size of the silica fine particles used was 200 nm or less.

[0179] Preparation Example 9 [Preparation of Composite Particle 9] 40 g of silica microparticles (Admatechs Co., Ltd., ADMAFINE SO-C2, average particle size 900 nm) and 2 g of vinyltrimethoxysilane (Kanto Chemical Co., Ltd.) were added to 200 mL of ethanol. The mixture was stirred at room temperature for 12 hours. After washing with ethanol, the silica microparticles were recovered using a centrifuge and then heated at 110°C for 1 hour to obtain vinyl-group-introduced silica microparticles (i.e., Composite Particle 9). Composite Particle 9 was not a particle having a polymer graft chain.

[0180] Test Example 1 [Dielectric Properties of Composite Particles] The dielectric properties of the composite particles were evaluated as follows: The relative permittivity and dielectric loss tangent of the composite particles were determined by measurement using a device in which a perturbation method cavity resonator (CP-580) manufactured by Kanto Electronics Application Development Co., Ltd. was connected to a network analyzer (manufactured by Agilent Technologies, product name: N5221A) using a cavity resonator perturbation method (CP-MA dielectric constant measurement software, manufactured by Kanto Electronics Application Development Co., Ltd.) at a temperature of 25°C and a measurement frequency of 10 GHz.

[0181] Specifically, the composite particles were packed into a Teflon (registered trademark) tube (manufactured by Chukoh Chemical Industry Co., Ltd.: PTFE tube, inner diameter 1.5 mm, outer diameter 2.5 mm) so that all of the composite particles were within the measurement range (6.75 mm to 36.35 mm from the bottom), to prepare a measurement sample. The packed weight of the composite particles was calculated by measuring the weight before and after packing, and the volume of the composite particles packed into the Teflon (registered trademark) tube was found from the packed weight and specific gravity of the composite particles.

[0182] The relative permittivity and dielectric loss tangent were calculated by the difference between the values ​​measured for an empty Teflon tube not filled with composite particles and the values ​​measured for a Teflon tube filled with composite particles. The main characteristics and dielectric properties of each preparation example are summarized in Table 1.

[0183]

[0184] The abbreviations in the table are as follows: PSt: polystyrene; PDVB: polydivinylbenzene; VTMS: vinyltrimethoxysilane.

[0185] Examples 1 to 6 and Comparative Examples 1 to 3 [Preparation of Resin Composition] First, each component other than the composite particles was added to toluene in the blending ratios (parts by mass) shown in Tables 2 and 3 so that the solids concentration was 60% by mass, and mixed. The mixture was stirred at room temperature for 24 hours. Thereafter, a toluene solution of the composite particles was added to the obtained liquid, and the composite particles were dispersed using a planetary centrifugal mixer. This resulted in a varnish-like resin composition (varnish).

[0186] Next, a precursor of a resin molded body was produced by heating and drying the obtained varnish for about 2 to 3 hours at 80°C. The obtained precursors of the resin molded body were then stacked and heated and pressed at a temperature of 200°C for 2 hours at a pressure of 3 MPa to obtain an evaluation substrate (resin molded body).

[0187] Test Example 2 [Dielectric Properties of Resin and Resin Molded Product] The dielectric properties of the resin and resin molded product were evaluated as follows: The relative permittivity and dielectric loss tangent of the resin and resin molded product were measured at a temperature of 25°C and a measurement frequency of 10 GHz using a device in which a perturbation method cavity resonator (CP-580) manufactured by Kanto Electronics Application Development Co., Ltd. was connected to a network analyzer (manufactured by Agilent Technologies, product name: N5221A).

[0188] Test Example 3 [Dispersibility of Composite Particles] The dispersibility of the composite particles in the resin molding was evaluated by observing the machined surface of the resin molding with a scanning electron microscope (SEM).

[0189] From the SEM images, 50 cross sections of composite particles were selected, and the major axis of each was visually read, and the average value was taken as the dispersed particle size. Composite particles with a dispersed particle size of 10 μm or less and 10 times or less the average particle size of the inorganic particles used were judged to have "good dispersibility," while those that did not satisfy any of the particle size specifications were judged to have "poor dispersibility." In Tables 2 and 3, composite particles with a dispersed particle size of 10 times or less the average particle size of the inorganic particles used are marked with a "+," and those with a dispersed particle size of more than 10 times are marked with a "-."

[0190] The compounding ratios of the resin moldings and the evaluation results are shown in Tables 2 and 3.

[0191]

[0192]

[0193] It can be seen from Tables 2 and 3 that the dispersibility of the composite particles in the resin molded articles (Examples 1 to 6) obtained using the resin composition of the present invention containing specific composite particles was superior to the dispersibility of the comparative resin molded articles (Comparative Examples 1 to 3). The reasons for the inferior dispersibility of the composite particles in Comparative Examples 1 to 3 are thought to be that the composite particles did not have polymer graft chains (Comparative Examples 1 and 3) and that the average particle size of the inorganic particles was 200 nm or less (Comparative Example 2).

[0194] With regard to the dielectric properties, it was found that Examples 1 to 6, which had excellent dispersibility of the composite particles, tended to be superior to the comparative Examples 1 to 3. This suggests that grafting polymer chains to inorganic particles improves the dispersibility of the composite particles in the resin composition or resin molded product, which contributes to improving the dielectric properties.

[0195] The components other than the composite particles are as follows. (Resin) The resin used was a curable resin obtained by crosslinking the following modified polyphenylene ether with TAIC, which will be described later. Modified polyphenylene ether compound (modified PPE): Noryl SA9000 resin manufactured by SABIC Innovative Plastics, with a relative dielectric constant ε of 2.6 at a frequency of 10 GHz and a temperature of 25°C and a weight average molecular weight of 2,000; this is a modified polyphenylene ether in which the terminal hydroxyl groups of polyphenylene ether are modified with methacrylic groups. The specific structure is represented by the following formula (2), and R in formula (2) ９ , R １０ , R １５ and R １６ is a methyl group, and R １１ ~R １４ is a hydrogen atom, X is a methacryl group, and Y is a dimethylmethylene group (i.e., represented by the following formula (3), R １７ and R １８ is a methyl group).

[0196]

[0197] (Cross-linking curing agent) TAIC: triallyl isocyanurate (TAIC manufactured by Nippon Kasei Chemical Industry Co., Ltd., molecular weight 249, number of terminal double bonds 3) (Reaction initiator) Initiator: 1,3-bis(butylperoxyisopropyl)benzene (Perbutyl P (PBP) manufactured by NOF Corporation) (Toughness improver) SBS: styrene-based thermoplastic elastomer (Tufprene A manufactured by Asahi Kasei Corporation)

[0198] Preparation Example 10 [Preparation of Composite Particle 10] a) Step of Bonding Polymerization Initiator Groups to the Particle Surface a-1) Introduction of Amino Groups onto the Surface of Silica Particles 40 g of silica particles (Admatechs Co., Ltd., ADMAFINE SO-C2, average particle size 900 nm) and 2 g of 3-aminopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-903) were added to 200 mL of ethanol. The mixture was stirred at room temperature for 12 hours. After washing with ethanol, the silica particles were collected using a centrifuge and then heated at 110°C for 1 hour to obtain amino group-introduced silica particles.

[0199] a-2) Introduction of polymerization initiator groups onto the surface of amino group-introduced silica microparticles 40 g of the above amino group-introduced silica microparticles, 200 mL of anhydrous THF, 1 mL of anhydrous triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1 mL of 2-bromoisobutyl bromide (BIBB) (manufactured by Tokyo Chemical Industry Co., Ltd.) were placed in a 500 mL eggplant-shaped flask and stirred at room temperature for 2 hours. After that, the mixture was washed with THF and anisole, and the polymerization initiator group-introduced silica microparticles into which 2-bromoisobutyryl groups had been introduced as polymerization initiator groups were recovered using a centrifuge and then stored as an anisole-wet product of polymerization initiator group-introduced silica microparticles.

[0200] b) A step of contacting particles having polymerization initiation groups on the surface with a monomer under living radical polymerization conditions. In a 500 mL separable flask, an anisole wet solution containing 12 g of the silica microparticles having polymerization initiation groups prepared above, 120 g of anisole, and 120 g of glycidyl methacrylate as a monomer were added, thoroughly stirred, and then subjected to reduced pressure and nitrogen substitution. Thereafter, the temperature was raised to 50 ° C., and an acetonitrile solution prepared by previously stirring 860 mg of Cu (I) Br (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured, and polymerization was initiated. Next, the mixture was stirred for 2 minutes, followed by ice water cooling and air bubbling, and then an excess of methanol was added to quench the reaction.

[0201] Thereafter, washing with methanol and removal of the solution by filtration were repeated three times, followed by washing with tetrahydrofuran and removal of the solution by filtration once to obtain silica microparticles grafted with polyglycidyl methacrylate (i.e., composite particles 10). Further, the obtained solid was added with tetrahydrofuran without being dried, and stored as a tetrahydrofuran solution.

[0202] The content of the polymer graft chains in the obtained composite particles 10 was 2.1% by mass, the number average molecular weight of the polymer graft chains was 12,000, and the graft density of the polymer graft chains was 0.19 chains / nm ２ The film thickness of the polymer graft chains was 3 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0203] Preparation Example 11 [Preparation of Composite Particles 11] Composite particles 11 were obtained in the same manner as in Preparation Example 10, except that in step b), 120 g of anisole and 120 g of glycidyl methacrylate were replaced with 180 g of anisole and 60 g of glycidyl methacrylate.

[0204] The content of the polymer graft chains in the obtained composite particle 11 was 1.6% by mass, the number average molecular weight of the polymer graft chains was 5,000, and the graft density of the polymer graft chains was 0.34 chains / nm ２ The film thickness of the polymer graft chains was 2 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0205] Preparation Example 12 [Preparation of Composite Particle 12] 40 g of silica microparticles (Admatechs Co., Ltd., ADMAFINE SO-C2, average particle size 900 nm) and 2 g of 3-glycidyloxypropyltrimethoxysilane (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to 200 mL of ethanol. The mixture was stirred at room temperature for 12 hours. After washing with ethanol, the silica microparticles were recovered using a centrifuge and then heated at 110°C for 1 hour to obtain glycidyl group-introduced silica microparticles (i.e., Composite Particle 12). Composite Particle 12 was not a particle having a polymer graft chain.

[0206] The main characteristics of Preparation Examples 10 to 12 are summarized in Table 4.

[0207]

[0208] The abbreviations in the table are as follows: PGMA: polyglycidyl methacrylate; GOPTMS: 3-glycidyloxypropyltrimethoxysilane.

[0209] Examples 7 to 9 and Comparative Example 4 [Preparation of Resin Composition] First, an epoxy resin was added to a tetrahydrofuran solution of composite particles (Preparation Examples 10 and 11) or composite particles (Preparation Example 12) at the blending ratio (parts by mass) shown in Table 5 and mixed. The mixture was dispersed into composite particles using a planetary mixer. Next, the obtained dispersion was heated and dried at 100°C for approximately 24 hours to prepare an epoxy resin dispersion.

[0210] Next, an amine curing agent was added to this dispersion in the proportion (parts by mass) shown in Table 5 so that the solids concentration was 60 mass% and mixed. The composite particles were dispersed in this mixture using a planetary mixer to obtain a resin composition (before curing). The shear viscosity of the resin composition in this state was measured using the following method.

[0211] Next, the obtained resin composition (before curing) was applied with an applicator and heated at 165° C. for about 2 to 3 hours to prepare a resin molded product (after curing).

[0212] [Measurement of Shear Viscosity] The shear viscosity (unit: Pa s) of the resin composition (before curing) was measured using a rheometer (MCR300, manufactured by Anton Paar). A 40 mm parallel plate was used as the spindle, and the temperature inside the measurement chamber was set to 110°C. The resin composition to be measured was heated to 110°C in advance and placed on a jig in a uniformly dissolved state.

[0213] The shear viscosity of each resin composition was measured by sweeping the shear rate from low to high within a range of shear rates from 0.1 (1 / s) to 100 (1 / s), and the shear viscosity value at a shear rate of 32.9 (1 / s) is shown in Table 5. The shear viscosity at a shear rate of 32.9 (1 / s) is an evaluation value of "ease of flow," and the smaller the value, the easier the resin composition is to inject.

[0214] [Coefficient of Linear Thermal Expansion (CTE)] The resin molded articles (after curing) obtained in Examples 7 to 9 and Comparative Example 4 were cut into strips of 5 mm width and 40 mm length to prepare samples. Using a thermomechanical analyzer (Hitachi High-Tech Corporation, TMA7100), the temperature of the strip samples was increased at a rate of 5°C per minute in a nitrogen atmosphere, and measurements were performed in tensile mode with a load of 20 mN and a span distance of 10 mm. The coefficient of linear thermal expansion was calculated by calculating the average coefficient of linear thermal expansion over a temperature range of 10°C to 30°C. A lower coefficient of linear thermal expansion indicates better dimensional stability.

[0215] Table 5 shows the compounding ratios of the resin molded bodies and the evaluation results.

[0216]

[0217] The machined surface of the resin molded product obtained in Example 8 was observed to evaluate the dispersibility of the composite particles in the same manner as in Test Example 3. As a result, it was found that the dispersed particle size of the composite particles was 1 μm, which was 10 times or less the average particle size of the inorganic particles.

[0218] The shear viscosity of the resin compositions (before curing) of Examples 7 to 9 was evaluated by comparing them with Comparative Example 4. It was found that the viscosity was lower than that of the resin compositions of the Comparative Examples. This suggests that incorporating composite particles in which polymer chains are grafted onto inorganic particles into a resin composition improves the dispersibility of the composite particles in the resin composition and in the resin molded article, thereby contributing to viscosity reduction. Because viscosity reduction is possible using the resin composition of the present invention, it was discovered that the particle amount can be increased, thereby potentially achieving a lower CTE. This indicates that the resin composition of the present invention can be suitably used as an underfill material or interlayer insulating material based on an epoxy resin.

[0219] Preparation Example 13 [Preparation of Composite Particles 13] Composite particles 13 were obtained in the same manner as in Preparation Example 10, except that in step b) of Preparation Example 10, the amount of silica microparticles having polymerization initiation groups was changed to 24 g, the amount of anisole to 180 g, and the amount of glycidyl methacrylate to 60 g, and that 1850 mg of 2,2′-bipyridyl (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 2080 mg of pentamethyldiethylenetriamine.

[0220] The content of the polymer graft chains in the obtained composite particle 13 was 0.7% by mass, the number average molecular weight of the polymer graft chains was 3,700, and the graft density of the polymer graft chains was 0.20 chains / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0221] Preparation Example 14 [Preparation of Composite Particles 14] Composite particles 14 were obtained in the same manner as in Preparation Example 13, except that in step b), the polymerization time (i.e., stirring time) was changed from 2 minutes to 1 minute.

[0222] The content of the polymer graft chains in the obtained composite particles 14 was 0.4% by mass, the number average molecular weight of the polymer graft chains was 2,200, and the graft density of the polymer graft chains was 0.20 chains / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0223] Preparation Example 15 [Preparation of Composite Particle 15] [Synthesis of a Silane Compound Having a Polymerization Initiator Group Other than a Halosulfonyl Group] 17.9 g of 3-aminopropyltrimethoxysilane (KBM-903, Shin-Etsu Chemical Co., Ltd.), 100 mL of anhydrous tetrahydrofuran (THF), and 16.8 mL of anhydrous triethylamine (Tokyo Chemical Industry Co., Ltd.) were added to a 500 mL eggplant-shaped flask. This mixture was ice-cooled, and when it reached 0°C, 14.8 mL of 2-bromoisobutyl bromide (BiBB) (Tokyo Chemical Industry Co., Ltd.) was added dropwise while maintaining the ice cooling, and the mixture was stirred for 4 hours. The solvent was then removed from the liquid phase obtained after filtration using an evaporator. The residue was dried at 50°C for 5 hours to obtain a silane compound having a bromoacyl group as a polymerization initiator group (this compound will be abbreviated as "APTMS-Br"). This silane compound was used as a silane coupling agent. The synthesis scheme for the aforementioned APTMS-Br is shown below.

[0224]

[0225] Step a) Bonding of Polymerization Initiator Groups to the Particle Surface: 50 g of silica microparticles (Admatechs, ADMAFINE SO-C2, average particle size 900 nm) and 0.23 g of anhydrous triethylamine as a catalyst were placed in a plastic bag and mixed by hand from the outside of the bag at room temperature for 5 minutes. 0.74 g of the APTMS-Br synthesized above and 0.74 g of ethanol were then added and mixed by hand from the outside of the bag at room temperature for 5 minutes. These were mixed at room temperature for 5 minutes using a crusher (Iwatani Corporation) and then allowed to stand for 12 hours. The silica microparticles were then washed with ethanol, recovered by centrifugation, and heated at 110°C for 1 hour to obtain silica microparticles bearing bromoacyl groups, which are polymerization initiator groups.

[0226] Step b) A step of contacting particles having polymerization initiating groups on their surfaces with a monomer under living radical polymerization conditions. Composite particles 15 were obtained in the same manner as in Preparation Example 13, except that in step b), the silica fine particles having bromoacyl groups bonded thereto, prepared above, were used as the silica fine particles having polymerization initiating groups.

[0227] The content of the polymer graft chains in the obtained composite particle 15 was 0.7% by mass, the number average molecular weight of the polymer graft chains was 3,400, and the graft density of the polymer graft chains was 0.22 chains / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0228] Preparation Example 16 [Preparation of Composite Particles 16] Composite particles 16 were obtained in the same manner as in Preparation Example 15, except that in step b), the obtained solid was not stored as a tetrahydrofuran solution but was subjected to vacuum drying at 60°C for 12 hours, and the obtained solid was crushed in a mortar to obtain a powder.

[0229] The content of the polymer graft chains in the obtained composite particles 16 was 0.7% by mass, the number average molecular weight of the polymer graft chains was 3,400, and the graft density of the polymer graft chains was 0.22 chains / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0230] Preparation Example 17 [Preparation of Composite Particles 17] Composite particles 17 were obtained in the same manner as in Preparation Example 16, except that in step b), the powder obtained by crushing in a mortar was further crushed in a jet mill. Name of the jet mill: Cojet System α-mkIII (manufactured by Seishin Enterprise Co., Ltd.)

[0231] Preparation Example 18 [Preparation of Composite Particles 18] Composite particles 18 were obtained in the same manner as in Preparation Example 16, except that in step b), 180 g of anisole, 60 g of glycidyl methacrylate, and 60 g of allyl methacrylate were used instead of 180 g of anisole and 60 g of glycidyl methacrylate.

[0232] The content of the polymer graft chains in the obtained composite particle 18 was 0.8% by mass, the number average molecular weight of the polymer graft chains was 3,800, and the graft density of the polymer graft chains was 0.22 chains / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer units (glycidyl methacrylate and allyl methacrylate) in the polymer graft chains was 100% by mass.

[0233] The main characteristics of Preparation Examples 13 to 18 are summarized in Table 6.

[0234]

[0235] The abbreviations in the table are as follows: PGMA: polyglycidyl methacrylate; PGMA-co-PAMA: copolymer of polyglycidyl methacrylate and polyallyl methacrylate.

[0236] Examples 10 to 14 and 16 [Preparation of Resin Compositions] First, the epoxy resin, amine curing agent, and each composite particle were mixed in the proportions shown in Table 7. The mixture was dispersed in a planetary centrifugal mixer to prepare a resin composition (before curing). Name of planetary centrifugal mixer: ARE-400TWIN (manufactured by Thinky Corporation)

[0237] Example 15 [Preparation of Resin Composition] First, epoxy resin, amine curing agent, and composite particles 16 were mixed in the proportions shown in Table 7. The composite particles were dispersed in the mixture using a planetary mixer, and then the mixture was kneaded using a three-roll mill to prepare a resin composition (before curing). Three-roll mill device name: BR-100V (manufactured by AMEX Corporation). Three-roll mill conditions: roll clearance 25 μm, rotation speed 300 rpm, 3 passes

[0238] Table 7 shows the compounding ratios of the resin molded bodies and the evaluation results.

[0239]

[0240] The machined surfaces of the resin molded articles obtained in Examples 10 to 16 were observed and the dispersibility of the composite particles was evaluated in the same manner as in Test Example 3. As a result, it was found that the dispersed particle size of the composite particles in all Examples was 1 to 2 μm, which was 10 times or less the average particle size of the inorganic particles.

[0241] Furthermore, when the shear viscosity of the resin compositions (before curing) in Examples 10 to 16 was evaluated, it was found to be in the range of 0.11 to 0.23 Pa s, which was a sufficiently low viscosity. Furthermore, a comparison of the shear viscosities in Examples 7, 8, 10, and 11 revealed that Example 8 had a lower shear viscosity than Example 7, that Example 10 had a lower shear viscosity than Example 8, and that Example 10 had a lower shear viscosity than Example 11. As described above, the number-average molecular weight of the polymer graft chains in the composite particles used in Example 10 was 3,700, while those in Examples 7, 8, and 11 were 12,000, 5,000, and 2,200, respectively. This suggests that in order to achieve a high viscosity-reducing effect, it is not necessarily the case that the number-average molecular weight is small, but rather that the number-average molecular weight must be within a certain appropriate range.

[0242] Examples 17 to 18 [Preparation of resin composition] An epoxy resin, an amine curing agent, and composite particles 16 were mixed in the blending ratios shown in Table 8. The mixture was dispersed in a planetary mixer to prepare a resin composition (before curing).

[0243] Example 19 [Preparation of Resin Composition] An epoxy resin, an amine curing agent, and Composite Particles 18 were mixed in the blending ratios shown in Table 8. The mixture was used in a planetary mixer to disperse the composite particles, thereby preparing a resin composition (before curing).

[0244] Table 8 shows the compounding ratios in the resin molded products after curing of the resin compositions and the evaluation results.

[0245]

[0246] The machined surfaces of the resin molded articles obtained in Examples 17 to 19 were observed and the dispersibility of the composite particles was evaluated in the same manner as in Test Example 3. As a result, it was found that the dispersed particle size of the composite particles in all Examples was 1 μm, which was 10 times or less the average particle size of the inorganic particles.

[0247] Furthermore, when the shear viscosity of the resin compositions (before curing) in Examples 17 to 19 was evaluated, it was found to be in the range of 0.12 to 0.14 Pa·s, which was a sufficiently low viscosity.

[0248] Preparation Example 19 [Preparation of Composite Particle 19] Composite Particle 19 was obtained in the same manner as Preparation Example 15, except that in step b), 180 g of anisole and 60 g of allyl methacrylate were used instead of 180 g of anisole and 60 g of glycidyl methacrylate, the polymerization time (i.e., the stirring time) was changed to 30 minutes, and methyl ethyl ketone (MEK) was added instead of tetrahydrofuran and stored as an MEK solution.

[0249] The content of the polymer graft chains in the obtained composite particle 19 was 0.5% by mass, the number average molecular weight of the polymer graft chains was 2,500, and the graft density of the polymer graft chains was 0.21 chains / nm ２ The film thickness of the polymer graft chain was 1 nm, and the content of the monomer unit (allyl methacrylate) in the polymer graft chain was 100% by mass.

[0250] Preparation Example 20 [Preparation of Composite Particle 20] Composite particle 19 was obtained in the same manner as in Preparation Example 15, except that in step b), 180 g of anisole and 60 g of cyclohexyl methacrylate were used instead of 180 g of anisole and 60 g of glycidyl methacrylate, the polymerization time (i.e., stirring time) was changed from 2 minutes to 30 minutes, the polymerization temperature was changed from 50°C to 80°C, and cyclohexane was added instead of tetrahydrofuran and the mixture was stored as a cyclohexane solution.

[0251] The content of the polymer graft chains in the obtained composite particles 20 was 2.6% by mass, the number average molecular weight of the polymer graft chains was 13,000, and the graft density of the polymer graft chains was 0.23 chains / nm ２ The film thickness of the polymer graft chains was 4 nm, and the content of the monomer unit (cyclohexyl methacrylate) in the polymer graft chains was 100% by mass.

[0252] The main characteristics of Preparation Examples 19 and 20 are summarized in Table 9.

[0253]

[0254] The abbreviations in the table are as follows: PAMA: polyallyl methacrylate; PcHMA: polycyclohexyl methacrylate.

[0255] Example 20 [Preparation of Resin Composition] An epoxy resin, a curing agent (triazine-containing phenolic resin), and Composite Particles 16 were mixed in the blending ratios shown in Table 10. The mixture was dispersed in a planetary mixer to prepare a resin composition (before curing).

[0256] Example 21 [Preparation of Resin Composition] Epoxy resin, phenolic curing agent (phenol novolac resin (MEK solution)), and MEK solution of composite particles 19 were mixed in the proportions shown in Table 10. An appropriate amount of curing accelerator was also added to this mixture. The composite particles were dispersed in this mixture using a planetary mixer. Next, the resulting dispersion was heated and dried at 100°C for approximately 24 hours to obtain a resin composition (before curing).

[0257] Example 22 [Preparation of Resin Composition] Epoxy resin, phenolic curing agent (MEK solution), and MEK solution of composite particles 16 were mixed in the proportions shown in Table 10. An appropriate amount of curing accelerator was also added to this mixture. The composite particles were dispersed in this mixture using a planetary mixer. The resulting dispersion was then heated and dried at 100°C for approximately 24 hours to obtain a resin composition (before curing).

[0258] Example 23 [Preparation of Resin Composition] Cycloolefin polymer (COP) (cyclohexane solution) and a cyclohexane solution of Composite Particles 20 were mixed in the blending ratios shown in Table 10. The mixture was dispersed into composite particles using a planetary mixer. The resulting dispersion was then heated and dried at 100°C for approximately 24 hours to obtain a resin composition (before curing).

[0259] Table 10 shows the compounding ratios in the resin molded products after curing of the resin compositions and the evaluation results.

[0260]

[0261] The machined surfaces of the resin molded articles obtained in Examples 20 to 23 were observed and the dispersibility of the composite particles was evaluated in the same manner as in Test Example 3. As a result, it was found that the dispersed particle size of the composite particles in all Examples was 2 to 6 μm, which was 10 times or less the average particle size of the inorganic particles.

[0262] Preparation Example 21 [Preparation of Composite Particles 21] Polydivinylbenzene-grafted silica microparticles (i.e., Composite Particles 21) were obtained in the same manner as in Preparation Example 2, except that silica microparticles (Admafine SO-C1, manufactured by Admatechs Co., Ltd., average particle size 500 nm) were used instead of the silica microparticles having polymerization initiating groups prepared in step a) of Preparation Example 1 above. Toluene was then added to the obtained solid without drying, and the resulting solid was stored as a toluene solution.

[0263] The content of the polymer graft chains in the obtained composite particle 21 was 5.0% by mass, the number average molecular weight of the polymer graft chains was 9,000, and the graft density of the polymer graft chains was 0.20 chains / nm ２ The film thickness of the polymer graft chains was 3 nm, and the content of the monomer unit (divinylbenzene) in the polymer graft chains was 100% by mass.

[0264] The main characteristics of Preparation Example 21 are summarized in Table 11.

[0265]

[0266] The abbreviations in the table are as follows: PDVB: polydivinylbenzene.

[0267] Example 24 [Preparation of Resin Composition] Each component other than Composite Particle 21 was added to toluene at the blending ratio (parts by mass) shown in Table 12 so that the solids concentration was 60 mass% and mixed. The mixture was stirred at room temperature for 24 hours. Thereafter, a toluene solution of the composite particles was added to the resulting liquid, and the composite particles were dispersed using a planetary mixer. This resulted in a varnish-like resin composition (varnish).

[0268] Next, a precursor of a resin molded body was prepared by heating and drying the obtained varnish at 80°C for about 2 to 3 hours. The obtained precursors of the resin molded body were then stacked and heated and pressed at a temperature of 200°C for 2 hours under a pressure of 3 MPa to obtain an evaluation substrate (resin molded body).

[0269] The compounding ratios of the resin molded bodies and the evaluation results are shown in Table 12.

[0270]

[0271] The machined surface of the resin molded article obtained in Example 24 was observed in the same manner as in Test Example 3 to evaluate the dispersibility of the composite particles. As a result, it was found that the dispersed particle size of the composite particles was 3 μm, which was 10 times or less the average particle size of the inorganic particles. It was also found that the dielectric properties tended to be excellent.

[0272] Preparation Example 22 [Preparation of Composite Particle 22] Composite particle 22 was obtained under the same conditions as in Preparation Example 5, except that the polymerization time was 10 minutes. The content of polymer graft chains in the obtained composite particle 22 was 2.0 mass %, the number average molecular weight of the polymer graft chains was 10,000, and the graft density of the polymer graft chains was 0.23 chains / nm ２ The film thickness of the polymer graft chains was 3 nm, and the content of the monomer unit (styrene) in the polymer graft chains was 100% by mass.

[0273] Preparation Example 23 [Preparation of Composite Particle 23] Composite Particle 23 was obtained under the same conditions as in Preparation Example 5, except that the polymerization time was 2 minutes. The content of polymer graft chains in the obtained Composite Particle 23 was 0.5 mass %, the number average molecular weight of the polymer graft chains was 4,000, and the graft density of the polymer graft chains was 0.23 chains / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer unit (styrene) in the polymer graft chains was 100% by mass.

[0274] The main characteristics of Preparation Examples 22 to 23 and Preparation Example 5 are summarized in Table 13. Regarding Preparation Example 5, Composite Particles 5 were obtained under the conditions of a polymerization temperature of 90°C and a polymerization time of 30 minutes, as described above in Preparation Example 5. The content of polymer graft chains in the obtained Composite Particles 5 was 6.1% by mass, the number average molecular weight of the polymer graft chains was 30,000, and the graft density of the polymer graft chains was 0.24 chains / nm ２ The film thickness of the polymer graft chains was 10 nm.

[0275]

[0276] The abbreviations in the table are as follows: PSt: polystyrene.

[0277] Examples 25-26 [Preparation of Resin Composition] As in Example 5, each component other than the composite particles was added to toluene at the blending ratio (parts by mass) shown in Table 14 so that the solids concentration was 60 mass% and mixed. The mixture was stirred at room temperature for 24 hours. Thereafter, a toluene solution of the composite particles was added to the resulting liquid, and the composite particles were dispersed using a planetary centrifugal mixer. This resulted in a varnish-like resin composition (varnish).

[0278] Test Example 4 [Settling Property of Composite Particles] The varnish obtained above was placed in a sample tube and allowed to stand at room temperature for 24 hours. After standing, separation occurred in the entire varnish, with a supernatant containing no composite particles at the top and composite particles at the bottom, and settling of the composite particles was observed. The height of the supernatant containing no composite particles was divided by the height of the entire varnish, and the result was multiplied by 100 to calculate the "settling rate (%) of the composite particles." The settling rate value was evaluated as settling property. The smaller the settling rate value, the more suppressed settling was, i.e., it was determined that the dispersibility of the inorganic particles in the dispersion was excellent.

[0279] The compounding ratios of the resin molded bodies and the evaluation results are shown in Table 14.

[0280]

[0281] It was found that the sedimentation rate was higher in Example 25 than in Example 5, and the sedimentation rate was higher in Example 26 than in Example 25, i.e., the sedimentation suppression effect weakened in this order. As described above, the number average molecular weight of the polymer graft chains in the composite particles used in Example 5 was 30,000, that in Example 25 was 10,000, and that in Example 26 was 4,000, and it was therefore confirmed that the higher the molecular weight of the polymer graft chains in the composite particles, the higher the sedimentation suppression effect.

[0282] Preparation Example 24 [Preparation of Composite Particles 24] Step a) Step of Bonding Polymerization Initiator Groups to the Particle Surface 15.6 g of silica microparticles 1 (hollow silica microparticles obtained in Preparation Example 1) and 0.23 g of anhydrous triethylamine as a catalyst were added to a plastic bag and mixed by hand from the outside of the bag at room temperature for 5 minutes. 0.74 g of the above-mentioned APTMS-Br and 0.74 g of ethanol were added to this and mixed by hand from the outside of the bag at room temperature for 5 minutes. These were mixed at room temperature for 5 minutes using a crusher (manufactured by Iwatani Corporation) and then allowed to stand for 12 hours. The silica microparticles were then washed with ethanol, and subsequently recovered by suction filtration. They were then heated at 110°C for 1 hour to obtain silica microparticles to which bromoacyl groups, which are polymerization initiator groups, were bonded.

[0283] Step b) A step of contacting particles having a polymerization initiator group on the surface with a monomer under living radical polymerization conditions. 3.7 g of the silica microparticles having a polymerization initiator group prepared above, 180 g of anisole, and 60 g of glycidyl methacrylate as a monomer were placed in a 500 mL separable flask, and after thorough stirring, the mixture was subjected to reduced pressure nitrogen substitution. Then, the temperature was raised to 50 ° C., and an acetonitrile solution prepared by previously stirring 860 mg of Cu (I) Br (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured into the flask, and polymerization was initiated. Then, the mixture was stirred for 2 minutes, and then cooled with ice water and air was bubbled, and an excess of methanol was added to quench the reaction.

[0284] Thereafter, washing with methanol and removal of the solution by filtration were repeated three times, followed by washing with toluene and removal of the solution by filtration once, followed by vacuum drying at 60° C. for 12 hours, and the resulting solid was crushed in a mortar to obtain a powder. The obtained powder was silica fine particles grafted with polyglycidyl methacrylate, and these fine particles were designated as composite particles 24.

[0285] The content of the polymer graft chains in the obtained composite particles 24 was 1.0 mass %, the number average molecular weight of the polymer graft chains was 3,000, and the graft density of the polymer graft chains was 0.19 / nm ２ The film thickness of the polymer graft chains was 1 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0286] Preparation Example 25 [Preparation of Composite Particle 25] Composite particle 25 was obtained in the same manner as in Preparation Example 24, except that in step b), the mixture was vacuum dried at 60°C for 12 hours, the resulting solid was crushed in a mortar to obtain a powder, and then further crushed in a jet mill.

[0287] Preparation Example 26 [Preparation of Composite Particles 26] [Preparation of Silica Fine Particles] In Preparation Example 1, the stirring speed and temperature were adjusted to obtain Emulsion A having a particle volume average particle size of 0.3 μm. Next, hollow silica particles (average particle size 0.6 μm, coefficient of variation 27%, BET specific surface area 21.0 m) were prepared under reaction conditions similar to those of Preparation Example 1. ２ The hollow silica particles were designated as silica fine particles 3.

[0288] [Preparation of Composite Particles] Silica microparticles grafted with polyglycidyl methacrylate (i.e., composite particles 26) were obtained in the same manner as in Preparation Example 24, except that the hollow silica microparticles 3 were used instead of the silica microparticles having polymerization initiation groups prepared in step a) of Preparation Example 1.

[0289] The content of the polymer graft chains in the obtained composite particles 26 was 1.4% by mass, the number average molecular weight of the polymer graft chains was 2,800, and the graft density of the polymer graft chains was 0.15 chains / nm ２The film thickness of the polymer graft chain was 6 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chain was 100% by mass.

[0290] The main characteristics of Preparation Examples 24 to 26 are summarized in Table 15.

[0291]

[0292] The abbreviations in the table are as follows: PGMA: polyglycidyl methacrylate.

[0293] Examples 27 to 29 [Preparation of Resin Compositions] First, an epoxy resin, an amine curing agent, and each composite particle were mixed in the blending ratios shown in Table 16. The mixture was dispersed in a planetary mixer to prepare a resin composition (before curing).

[0294] Example 30 [Preparation of Resin Composition] An epoxy resin, a phenolic curing agent, and Composite Particles 26 were mixed in the blending ratios shown in Table 16. The mixture was used in a planetary-revolution mixer to disperse the composite particles, thereby preparing a resin composition (before curing).

[0295] Table 16 shows the compounding ratios of the resin molded bodies and the evaluation results.

[0296]

[0297] The machined surfaces of the resin molded articles obtained in Examples 27 to 30 were observed and the dispersibility of the composite particles was evaluated in the same manner as in Test Example 3. As a result, it was found that the dispersed particle size of the composite particles in all Examples was 1 to 5 μm, which was 10 times or less the average particle size of the inorganic particles.

[0298] In Example 29, the shear viscosity of the resin composition (before curing) and the CTE of the resin molded article (after curing) were evaluated. As a result, the shear viscosity was 0.17 Pa s and the CTE was 30.5 ppm. This indicates that the resin composition of Example 29 has a sufficiently low viscosity and that the resin molded article of Example 29 has excellent dimensional stability.

[0299] Details of the main components other than the composite particles in the above examples are as follows: (Resins) Bisphenol F type epoxy resin (Mitsubishi Chemical Corporation, JER807, epoxy equivalent: 160-175 g / eq) Bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, JER828, epoxy equivalent: 184-194 g / eq) Aminophenol type epoxy resin (Mitsubishi Chemical Corporation, JER630, epoxy equivalent: 98 g / eq) Biphenyl aralkyl type epoxy resin (Nippon Kayaku Co., Ltd., NC-3000-H, epoxy equivalent: 290 g / eq) Cycloolefin polymer (COP) (Zeonex K22R, Nippon Zeon Co., Ltd., glass transition temperature: 143°C)

[0300] (Curing agent) Aromatic amine curing agent (KAYAHARD AA, manufactured by Nippon Kayaku Co., Ltd., amine equivalent: 64 g / eq) Triazine-containing phenolic resin (LA7052, manufactured by DIC Corporation, hydroxyl equivalent: 120 g / eq) Phenol novolac resin (TD-2090-60M, manufactured by DIC Corporation, hydroxyl equivalent: 105 g / eq)

[0301] (Curing accelerator) 2-ethyl-4-methylimidazole (Tokyo Chemical Industry Co., Ltd.)

[0302] The resin composition of the present invention has excellent dielectric properties or viscosity characteristics, and therefore can be used in fields such as adhesive films, sheet-like laminate materials such as prepregs, solder resists, underfill materials, die bonding materials, semiconductor encapsulants, hole-filling resins, component-embedding resins, circuit boards (laminates, multilayer printed wiring boards, etc.), and semiconductor devices.

Claims

1. A resin composition containing composite particles having polymer graft chains on the surface of inorganic particles, and a resin, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin having a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin having a melting point, Tm, of 230°C or higher.

2. The resin composition according to claim 1, wherein the resin is an epoxy resin, a modified polyphenylene ether resin, a fluororesin, a cycloolefin resin, or a polyimide resin.

3. The graft density of the polymer graft chains is 0.01 chains / nm ２ The resin composition according to claim 1 or 2.

4. The resin composition according to any one of claims 1 to 3, wherein the polymer graft chain contains, as a monomer unit, one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, fluorine-based monomers, unsaturated olefin-based monomers, conjugated diene-based monomers, and monomers having an amino group, a hydroxy group, or a glycidyl group.

5. A resin composition according to any one of claims 1 to 4, wherein the number average molecular weight of the side chains of the polymer graft chains is 10 or more and 1,000 or less.

6. A resin composition according to any one of claims 1 to 5, wherein the inorganic particles are silica, and the total content of alkali metals and alkaline earth metals relative to the content of silica in the inorganic particles is 50 ppm by mass or less.

7. The resin composition according to any one of claims 1 to 6, wherein the composite particles have a dielectric loss tangent tanδ of less than 0.01 at a frequency of 10 GHz and a temperature of 25°C.

8. The resin composition according to any one of claims 1 to 7, wherein the composite particles have the polymer graft chain via a structure represented by the following formula (A): (polymer graft chain)-X-(CH ２ ) ｍ -Si-(R １ ) (R ２ ) (R ３ ) Formula (A) (In formula (A), -X- is a divalent group, one of which is -(CH ２ ) ｍ The other bonded to the polymer graft chain. m is an integer of 0 to 12. R １ , R ２ and R ３ At least one of the groups is bonded to the particles by forming a metalloxane bond, and the groups not bonded to the particles are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, a hydrogen atom, a hydroxy group, or a halogen atom.

9. The resin composition according to any one of claims 1 to 8, wherein the polymer graft chains contain 10% by mass or more of one or more monomer units selected from the group consisting of styrene, divinylbenzene, glycidyl methacrylate, allyl methacrylate, and cyclohexyl methacrylate.

10. A resin composition according to any one of claims 1 to 9, wherein the resin is an epoxy resin, and the polymer graft chains contain 50 mass % or more of monomer units having an SP value of 10 or more and 12 or less.

11. The resin composition according to any one of claims 1 to 9, wherein the resin is a modified polyphenylene ether resin, and the polymer graft chains contain 50 mass% or more of monomer units having an SP value of 8 or more and 10 or less.

12. The resin composition according to any one of claims 1 to 11, which is a low dielectric resin composition.

13. The resin composition according to any one of claims 1 to 11, which is a resin composition for low dielectric materials.

14. The resin composition according to any one of claims 1 to 11, which is used for copper-clad laminates, interlayer insulating films, or primary mounting underfill materials.

15. A method for producing a resin composition, comprising a step of mixing or kneading composite particles having polymer graft chains on the surface of inorganic particles and a resin, wherein the inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin with a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin with a melting point, Tm, of 230°C or higher.

16. Use of composite particles having polymer graft chains on the surface of inorganic particles and a resin as a resin composition, wherein the average particle size of the inorganic particles is greater than 200 nm and less than or equal to 3,000 nm, and the resin is a resin that satisfies at least one of the following conditions (1) to (3): (1) A curable resin. (2) A thermoplastic resin with a glass transition point, Tg, of 135°C or higher. (3) A thermoplastic resin with a melting point, Tm, of 230°C or higher.

17. Use of the resin composition according to any one of claims 1 to 11 for copper-clad laminates, interlayer insulating films, or primary mounting underfill materials.

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