Composite particle

Abstract

To provide inorganic particles that exhibit superior dispersibility within a resin, and a resin composition including the inorganic particles.SOLUTION: Composite particles having polymer graft chains on the surface of inorganic particles, wherein the inorganic particles are hollow particles, and the average particle diameter of the inorganic particles is more than 200 nm and 3,000 nm or less; and a resin composition containing the composite particles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to composite particles. [Background technology]

[0002] In recent years, there has been a demand for smaller electronic devices, faster signal speeds, and higher wiring density. To meet these demands, build-up substrates are required to have a low relative dielectric constant, a low dielectric loss tangent, a low thermal expansion coefficient, and multi-layering. To meet these demands, Patent Document 1 considers blending hollow particles into a low dielectric loss tangent resin to achieve a low dielectric loss tangent and a low thermal expansion coefficient. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-031409 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because inorganic particles have low dispersibility in organic resins, mixing the two often results in the inorganic particles settling over time or aggregation occurring between the inorganic particles, and the expected performance improvement from blending the particles tends not to be achieved. Furthermore, curable resins or resins that have a melting point of 230° C. or less or no glass transition point are difficult to melt and knead, making it difficult to disperse inorganic particles therein.

[0005] The present invention has been made in view of the above circumstances, and relates to providing inorganic particles that are highly dispersible in resins, and resin compositions containing such particles. [Means for solving the problem]

[0006] The present invention relates to the following [1] to

[10] . [1] Composite particles having polymer graft chains on the surface of inorganic particles, the inorganic particles are hollow particles, The inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm. composite particles. [2] The composite particles according to [1], wherein the porosity of the inorganic particles is 50% by volume or more and 80% by volume or less. [3] The graft density of the polymer graft chains in the composite particles is 0.01 chains / nm 2 The composite particle according to [1] or [2] above. [4] The composite particle according to any one of [1] to [3] above, wherein the polymer graft chain is a polymer composed of one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic-based 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 composite particles according to any one of the above [1] to [4], wherein the inorganic particles are silica. [6] The composite particles 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 mass ppm or less. [7] The composite particle according to any one of the above [1] to [6], which is a composite particle having the polymer graft chain via a structure represented by the following formula (A): (polymer graft chain)-X-(CH2) m -Si-(R 1 )(R 2 )(R 3 )...Equation (A) (In formula (A), -X- is a divalent group, one of which is -(CH2) to Si in formula (A). m The other end is bonded to a polymer graft chain. m is an integer of 0 to 12. 1 , R 2 and R 3At 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. [8] A resin composition containing the composite particles according to any one of [1] to [7] above and a resin. [9] A resin composition for low dielectric materials, comprising the composite particles according to any one of [1] to [7] above and a resin.

[10] A low dielectric resin composition containing the composite particles according to any one of [1] to [7] above and a resin. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide inorganic particles that are highly dispersible in resins, and resin compositions containing such particles. [Brief explanation of the drawings]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an example of bonding between inorganic particles and polymer graft chains in composite particles. Figure 1 assumes that R1, R2, and R3 in formula (A) all form siloxane bonds with silica in the inorganic particles. In Figure 1, the area surrounded by the dashed line between the inorganic particles and the polymer graft chains corresponds to X in formula (A). DETAILED DESCRIPTION OF THE INVENTION

[0009] As a result of investigations, the present inventors have found that the dispersibility of hollow inorganic particles in resins can be improved by using composite particles having polymer graft chains on the surfaces of the particles. Although the mechanism by which this effect is achieved is unclear, it is presumed that the dispersibility of the composite particles is improved by the entanglement and interaction of the polymer graft chains, which have a high affinity with the matrix resin. Therefore, by using composite particles having such polymer graft chains on the surface of inorganic particles, improvements can be expected in the dielectric properties, surface smoothness, low thermal expansion, high rigidity, vibration damping, adhesion, and viscosity reduction of the resin composition and its cured product (resin molded body).

[0010] <Composite particles> The composite particles of the present invention are composite particles having polymer graft chains on the surfaces of inorganic particles, the inorganic particles being hollow particles, and the average particle size of the inorganic particles being greater than 200 nm and not greater than 3,000 nm.

[0011] [Inorganic particles] The composite particles have polymer graft chains on the surfaces of inorganic particles. The inorganic particles may be inorganic particles known as fillers, 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 include plate-like, granular, needle-like, and fibrous shapes.

[0012] The average particle size of the inorganic particles is greater than 200 nm, preferably 300 nm or greater, more preferably 400 nm or greater, even more preferably 500 nm or greater, and even more preferably 1000 nm or greater, 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 particles is 3,000 nm or less, preferably 2,500 nm or less, more preferably 2,000 nm or less, and even more preferably 1,200 nm or less. The reason why the average particle size of the inorganic particles is greater than 200 nm is that a smaller average particle size increases the specific surface area, 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 smaller particle size is thought to increase viscosity and deteriorate processability. Furthermore, the smaller the particle size, the more easily particles approach and contact each other, which may result in increased aggregation. Another presumed cause of increased aggregation is the stronger interaction between particles due to inertial forces and gravity. For this reason, even if polymer graft chains are attached, it is expected that dispersibility will decrease if the average particle size is smaller than a certain range, and it is thought 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, and is measured by the method described in the examples below.

[0013] The inorganic particles are particles having a predetermined porosity, i.e., hollow particles. From the viewpoint of obtaining a molded article of the resin composition exhibiting desired dielectric properties, the porosity of the inorganic particles is preferably 50% by volume or more, more preferably 55% by volume or more, and even more preferably 60% by volume or more. On the other hand, from the viewpoint of the mechanical strength of the particles, the porosity of the inorganic particles is preferably 80% by volume or less, more preferably 77% by volume or less, even more preferably 74% by volume or less, and even more preferably 70% by volume or less. The porosity of the 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 in order to exhibit 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] Commercially available inorganic particles can be used, and when hollow silica particles are used as the inorganic particles, they can be produced by a known method, for example, the method described below.

[0016] [Method for producing hollow silica particles] The hollow silica particles can be produced, for example, by a method including the following steps. Step A: A step of preparing an aqueous emulsion of a hydrophobic liquid using 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 hollow silica particle precursors. Step C: A step of heat-treating the hollow silica particle precursor obtained in Step B at a temperature higher than 1000°C and lower than 1200°C for 1 hour or more.

[0017] Process A In step A, cationic surfactant A and a hydrophobic liquid are mixed and stirred with 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 an aqueous emulsion of the hydrophobic liquid can be carried out by a general method.

[0018] 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 to produce a more uniform and stable emulsion of the hydrophobic liquid. Examples of water-compatible organic solvents include lower alcohols such as methanol, ethanol, and isopropyl alcohol, and acetone. From the viewpoint of instantly reducing the solubility of the hydrophobic liquid in liquid A, the content of water 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.

[0019] 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 (1) or general formula (2): [R 1 R 3 3N] + X - (1) [R 1 R 2 R 3 2N] + X - (2)

[0020] In general formula (1) and general formula (2), 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 multiple R 3 may be different groups, and X - indicates 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 the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. 3is preferably a methyl group.

[0021] X in general formulas (1) and (2) - From the viewpoint of easy decomposition and volatilization during firing, X is preferably at least one type selected from monovalent anions such as halogen ions, hydroxide ions, and nitrate ions. - The cation is more preferably a halide ion, and even more preferably a chloride ion.

[0022] Examples of the alkyltrimethylammonium salt represented by general formula (1) 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.

[0023] Examples of the dialkyldimethylammonium salt represented by the general formula (2) include dibutyldimethylammonium chloride, dihexyldimethylammonium chloride, dioctyldimethylammonium chloride, dihexyldimethylammonium bromide, dioctyldimethylammonium bromide, dilauryldimethylammonium bromide, and ditetradecyldimethylammonium bromide.

[0024] 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.

[0025] Hydrophobic liquid The hydrophobic liquid is preferably one that can form emulsified droplets (emulsified oil droplets) in water. In addition, because liquid A containing water is used as the dispersion medium and in terms of improving the utilization efficiency of the hydrophobic liquid, the temperature range in which the hydrophobic liquid is in a 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.

[0026] 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 hydrophobic liquid droplets within an appropriate range, and is preferably 0.8 or less, more preferably 0.75 or less, even more preferably 0.7 or less.

[0027] 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.

[0028] 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. The volume average particle diameter 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, from the viewpoint of keeping the average particle diameter of the hollow silica particles within the above range.

[0029] Process 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 cationic surfactant B on the surface of the hydrophobic liquid droplets and containing the hydrophobic liquid inside.

[0030] The silanol precursor, alkaline substance, and cationic surfactant B may be added to the aqueous emulsion either simultaneously or separately, or the aqueous emulsion may be added to either the silanol precursor or the cationic surfactant B, and then the remaining one may be added.

[0031] 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, for example, by 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, for example, by 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, for example, by freeze-drying or the like.

[0032] 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 (3) to (7), or combinations thereof. SiY4(3) R 3 SiY3(4) R 3 2SiY2(5) R 3 3SiY (6) Y3Si-O-SiY3(7)

[0033] In general formulas (3) to (7), 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.

[0034] In the general formulas (4) to (6), 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.

[0035] In the general formulas (3) to (7), 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.

[0036] The silanol precursor is preferably selected from compounds represented by general formula (3) and general formula (7). 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 (3) and general formula (7) in which Y is an alkoxy group having 2 to 4 carbon atoms, and more preferably selected from compounds represented by general formula (3) and general formula (7) in which Y is an ethoxy group. The silanol precursors can be used alone or in combination of two or more.

[0037] 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, and is preferably 90 or less, more preferably 80 or less, even more preferably 75 or less, from the viewpoint of keeping the porosity of the hollow silica particles within an appropriate range.

[0038] 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, or 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. The cationic surfactant B may be used alone or in combination of two or more kinds.

[0039] 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.

[0040] alkaline substances The silanol precursor is hydrolyzed by an alkaline substance to form silanol, which is then dehydrated and condensed to form silica. Specific examples of alkaline substances 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.

[0041] 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.

[0042] The alkaline substance may contain, in addition to the hydroxide salt of the quaternary ammonium, for example, an alkali metal salt or an alkaline earth metal salt, but in order to reduce the content of alkali metals and alkaline earth metals in the resulting hollow silica particles, the total content of alkali metals and alkaline earth metals relative to the silanol precursor is 50 ppm by mass or less, calculated as silica (SiO), preferably 30 ppm by mass or less, more preferably 10 ppm by mass or less.

[0043] By mixing an alkaline substance with cationic surfactant B and contacting it with a silanol precursor, hollow silica particles with a small maximum particle size and an appropriate coefficient of variation can be obtained. The contact of the mixture of alkaline substance and cationic surfactant B with the silanol precursor may be carried out by adding the mixture of alkaline substance and 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 alkaline substance and cationic surfactant B. However, from the viewpoints of increasing porosity and productivity by increasing the synthesis concentration, it is preferable to add the mixture of alkaline substance and cationic surfactant B to a reaction system containing the silanol precursor.

[0044] 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.

[0045] 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.

[0046] 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, in which pores templated by a cationic surfactant are formed radially toward the particle center.

[0047] Process C In step C, the hollow silica particle precursor obtained in step B is heat-treated at a temperature exceeding 1000°C and not exceeding 1200°C for at least 1 hour to decompose and volatilize the cationic surfactant present in the outer shell of the hollow silica particle precursor, volatilize the hydrophobic liquid inside, and then close the pores present in the outer shell by calcination to obtain hollow silica particles with a uniform outer shell.

[0048] The heat treatment temperature in step C is preferably 1010°C or higher, more preferably 1030°C or higher, and even more preferably 1050°C or higher, from the viewpoint of reducing silanol groups on the surface of the hollow silica particles, and is 1200°C or lower, preferably 1190°C or lower, more preferably 1180°C or lower, and even more preferably 1160°C or lower, from the viewpoint of avoiding aggregation of the hollow silica particles.

[0049] 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.

[0050] [Polymer graft chain] Examples of the polymer graft chain include a polymer composed of 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. Here, the polymer constituting the polymer graft chain may be a homopolymer or a copolymer. From the viewpoints of exhibiting desired dielectric properties and 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.

[0051] 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 methacrylic acid. 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.

[0052] From the viewpoint of dispersibility of the composite particles, the polymer graft chain preferably 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.

[0053] From the viewpoint of dispersibility of the composite particles and reactivity with the resin, the content of such monomer units 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.

[0054] Here, the content of the monomer unit in the polymer graft chain is determined as follows. The content of the above 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.

[0055] [Method for producing composite particles] The composite particles can be obtained by bonding polymer graft chains to the surfaces of inorganic particles. The method for bonding the 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 the polymer graft chains are polymerized from polymerization initiation points on the particle surfaces is preferred.

[0056] 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.

[0057] 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.

[0058] More specifically, an example of a method for producing 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: Binding a polymerization initiating group to the particle surface Step 2: A step of contacting particles having polymerization initiation groups on the surface with a monomer under living radical polymerization conditions.

[0059] Step 1 is a step in which the particles are reacted with, for example, a coupling agent to bond 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 together to react with each other. 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 particles is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 1.0 part by mass or more, while from the viewpoint of suppressing reaction between coupling agents, it 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.

[0060] 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 initiator group. In this case, it is preferable to use 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 initiator group and a functional group that reacts with an amino group or a hydroxyl group" as a component that has the same effect as a coupling agent. From the viewpoint of bonding a polymer graft chain to the particle surface, it is more preferable to include a step of introducing a polymerization initiator group onto the particle surface after the step of introducing an amino group or a hydroxyl group onto the particle surface.

[0061] The compound used in the step of introducing amino groups or hydroxyl groups onto the particle surface is a compound having a group that bonds to the particle surface and an amino group or a hydroxyl group. From the viewpoint of availability, the compound is preferably a silane compound, more preferably an aminoalkylsilane compound, and even more preferably 3-aminopropyltrimethoxysilane.

[0062] The compound used in the step of introducing a polymerization initiating group is a compound having a functional group that reacts with a polymerization initiating group and 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.

[0063] 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-(CH2) m -Si-(R 1 )(R 2 )(R 3 )...Equation (A) (In formula (A), -X- is a divalent group, one of which is -(CH2) to Si in formula (A). m The other end is bonded to a polymer graft chain. m is an integer of 0 to 12. 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.

[0064] 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:

[0065] [ka]

[0066] Of these, the following structures are more preferred:

[0067] [ka]

[0068] -(CH2) in formula (A) m In the formula (A), m is an integer of 0 to 12. When m is 0, -(CH2) 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, -(CH2) m One or more -CH2- in - may be substituted with a phenylene group and / or -NH-.

[0069] 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.

[0070] For example, when the particles originally have polymerization initiation sites or when they are formed as a result of surface treatment such as plasma treatment, they have polymerization initiation groups and therefore step 1 is not necessary. However, when using silica, mica, talc, glass filler, etc. that do not have polymerization initiation groups, step 1 may be performed. From the viewpoint of adjusting the graft density, a silane coupling agent that does not contain a polymerization initiation group may be added to the silane coupling agent containing a polymerization initiation group in step 1. In the step of bonding the polymerization initiation groups to the particle surface in step 1, a method in which the particles are dispersed in a dispersion medium is preferred from the viewpoint of preventing particle aggregation.

[0071] 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 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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. 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 directly bonded to a heteroatom-containing conjugated group, such as a carbonyl group, a cyano group, or a sulfonyl group, or bonded to an atom adjacent to such a 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.

[0076] [ka]

[0077] In the above formulas (1) and (2), R1 and R2 each independently represent 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.

[0078] The polymerization initiating group of formula (1) may have a carbonyl group, as shown in the following general formula (3): In formula (3), R1, R2, and Z have the same meanings as R1, R2, and Z in formula (1).

[0079] [ka]

[0080] Specific examples of the polymerization initiating group of formula (3) are shown in the following chemical formula.

[0081] [ka]

[0082] 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.

[0083] Specific examples of suitable coupling agents include 3-(2-bromoisobutyrylamino)propyltrimethoxysilane and 3-(2-bromoisobutyryloxy)propyltrimethoxysilane.

[0084] Step 2 is a step of contacting particles having polymerization initiation groups on the surface with a monomer under living radical polymerization conditions. In step 2, in which particles having polymerization initiation groups on their surfaces are brought into contact with a monomer under living radical polymerization conditions, a method is preferred in which the particles, monomer, and composite particles are dispersed in a dispersion medium and then polymerized, in order to prevent the particles, monomer, and composite particles from agglomerating.

[0085] 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 both a group that bonds to the particle surface and a polymerization initiating group, and compounds having either a group that bonds to the particle surface or a polymerization initiating group. In the present invention, the particles having polymerization initiation groups on the surface in step 2 are preferably the particles obtained in step 1 above.

[0086] The amount of particles having polymerization initiation groups on their surfaces to be charged in step 2 is preferably 0.02 parts by mass or more and preferably 0.3 parts by mass or less per part by mass of the dispersion medium.

[0087] Examples of the monomer in step 2 include styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, fluorine-based monomers, unsaturated olefin-based monomers, conjugated diene-based monomers, etc., and also monomers having specific groups in their side chains (for example, monomers having an amino group, a hydroxy group, or a glycidyl group) can be used. Specific examples of the monomers suitable for use in step 2 include those described above in "Specific examples of monomers as raw materials for polymer graft chains."

[0088] The amount of the monomer charged in step 2 is preferably 1 part by mass or more and preferably 10 parts by mass or less per part by mass of the particles having polymerization initiation groups on the surface thereof.

[0089] 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).

[0090] 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.

[0091] 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.

[0092] The reaction conditions in step 2, for example, the reaction temperature, are preferably 40°C or higher and 90°C or lower. The reaction time is preferably 1 minute or more and 120 minutes or less.

[0093] 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.

[0094] [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 or more 2 On the other hand, from the viewpoint of ease of grafting of polymer chains, it is preferable to use 2 chains / nm. 2 Less than or equal to 1.5 chains / nm, more preferably 1.5 chains / nm 2 Even more preferably, 1 chain / nm 2 Even more preferably 0.5 chains / nm or less 2 The following is the result. The graft density of the composite particles is measured by the method described in the Examples below.

[0095] 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, and even more preferably 1 nm or more, and from the same viewpoint, 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 25 nm or less, and even more preferably 10 nm or less. The film thickness of the polymer graft chains is calculated by the method described in the Examples below.

[0096] From the viewpoint of dispersibility of the composite particles in the resin composition, the number average molecular weight of the polymer graft chains in the composite particles is preferably 1,000 or more, more preferably 1,500 or more. From the same viewpoint, the number average molecular weight is preferably 1,000,000 or less, more preferably 500,000 or less, even more preferably 200,000 or less, still more preferably 100,000 or less, still more preferably 50,000 or less, still more preferably 30,000 or less, still more preferably 20,000 or less, still more preferably 12,000 or less, still more preferably 8,000 or less, and still more preferably 4,500 or less. The number average molecular weight of the polymer graft chains is measured by the method described in the examples below.

[0097] From the viewpoint of dispersibility of the composite particles, the content of polymer graft chains in the composite particles is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and is preferably 6.0% by mass or less, more preferably 4.0% by mass or less, even more preferably 2.0% by mass or less.

[0098] From the viewpoint of improving dispersibility, 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 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 resulting polymer graft chain, polyglycidyl methacrylate, has the 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:

[0099] [ka]

[0100] As mentioned above, if the part outside the carbonyl bond in polyglycidyl methacrylate 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 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.

[0101] From the viewpoint of obtaining a molded article of the resin composition exhibiting desired dielectric properties, the average particle size of the composite particles is preferably greater than 250 nm, more preferably 300 nm or more, and even more preferably 400 nm or more. On the other hand, from the viewpoint of improving the appearance of the resin composition, the average particle size of the composite particles is preferably 3,000 nm or less, more preferably 2,500 nm or less, and even more preferably 2,000 nm or less. The average particle size of the inorganic particles in the composite particles is measured by the same method as that for the average particle size of the inorganic particles, that is, by the method described in the Examples below.

[0102] 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.

[0103] <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 gradually decreases as it melts, and then curing begins, and the viscosity gradually increases. In such a case, the semi-cured state may refer to a state between when the viscosity starts to gradually decrease and when it is completely cured.

[0104] Resins used in the resin composition of the present invention include thermosetting resins and thermoplastic resins. Examples of thermosetting resins include polyurethane resins, urea resins, phenolic resin foams, unsaturated polyester resins, alkyd resins, melamine resins, epoxy resins, silicon 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. 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.

[0105] 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.

[0106] 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.

[0107] A preferred embodiment of the resin composition of the present invention is In the above-described resin composition, 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, this resin composition is another preferred embodiment of the resin composition of the present invention.

[0108] In the above embodiment, from the viewpoint of dispersibility of the composite particles, the monomer units in the polymer graft chains are 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.

[0109] Another preferred embodiment of the resin composition of the present invention is In the above-described resin composition, 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 or more and 10 or less. 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.

[0110] In the above embodiment, 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, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 100% by mass.

[0111] 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).

[0112] The main monomers used as 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).

[0113] [Method for producing resin composition] Such a resin composition of the present invention can be produced by a production method including a step of mixing or kneading the composite particles of the present invention and a resin. For example, a production method including a step of melt-kneading a resin and composite particles can be mentioned. For melt-kneading, a known kneading machine 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 the melt-kneading time are not necessarily set depending on the type of raw materials used, but are preferably 170 to 300°C and 15 to 900 seconds.

[0114] As an example of the production method, a method in which the components are kneaded without being thermally melted will be described below. First, each component that can be dissolved in an organic solvent is added to the organic solvent and dissolved. Heating may be performed as necessary. Subsequently, components that are insoluble in the organic solvent 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. Components that are insoluble in organic solvents are preferably dispersed in the organic solvent in advance, using a ball mill, a bead mill, a planetary mixer, a roll mill, a rotary mixer, a planetary mixer, a high-pressure homogenizer, an ultrasonic homogenizer, or the like. The organic solvent used here is not particularly limited as long as it dissolves the modified polyphenylene ether compound and the crosslinking curing agent and does not inhibit the curing reaction, and specific examples include toluene and methyl ethyl ketone (MEK).

[0115] [Dielectric properties of resin composition] The smaller the dielectric constant and dielectric loss tangent of the cured product of the resin composition of the present invention, the better. For example, the 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, even more preferably 2.3 or less, even more preferably 2.0 or less, and even more preferably 1.8 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, even more preferably 0.006 or less, even more preferably 0.005 or less, and even more preferably 0.004 or less. Such dielectric properties can be determined by the method described in the Examples.

[0116] <Resin composition for low dielectric material and low dielectric resin composition> The resin composition for low dielectric materials of the present invention contains the composite particles of the present invention and a resin.Further, the low dielectric resin composition of the present invention contains the composite particles of the present invention and a resin. 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 resin composition for low dielectric materials, a low dielectric resin composition, a resin composition for copper-clad laminates, a resin composition for primary mounting underfill materials, or a resin composition for interlayer insulation materials. Therefore, the resin composition for low dielectric materials and the low dielectric resin composition of the present invention are compositions containing the above-mentioned composite particles of the present invention and a resin.

[0117] The resin composition, resin composition for low dielectric material, low dielectric resin composition, 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.

[0118] The applications of the resin composition of the present invention, the resin composition for low dielectric materials, the low dielectric resin composition, the resin composition for copper-clad laminates, the resin composition for primary mounting underfill materials, or the resin composition for interlayer insulating materials are not particularly limited, and the resin composition 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 (laminates, multilayer printed wiring boards, etc.), and semiconductor devices.

[0119] The present invention also includes the following aspects.

[0120] <1> A composite particle having a polymer graft chain on the surface of an inorganic particle, the inorganic particles are hollow particles, The inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm. composite particles.

[0121] <2> The porosity of the inorganic particles is 50% by volume or more and 80% by volume or less. <1> The composite particle according to claim 1. <3> The graft density of the polymer graft chains in the composite particles is 0.01 chains / nm 2 The above <1> or <2> The composite particle according to claim 1. <4> the polymer graft chain is a polymer composed of one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic-based 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; <1> ~ <3> The composite particle according to any one of the preceding items. <5> The inorganic particles are silica. <1> ~ <4> The composite particle according to any one of the preceding items. <6> 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 mass ppm or less; <1> ~ <5> The composite particle according to any one of the preceding items. <7> The polymer graft chains are composite particles having a structure represented by the following formula (A): <1> ~ <6> The composite particle according to any one of the preceding items. (polymer graft chain)-X-(CH2) m -Si-(R 1 )(R 2 )(R 3 )...Equation (A) (In formula (A), -X- is a divalent group, one of which is -(CH2) to Si in formula (A). m The other end is bonded to a polymer graft chain. m is an integer of 0 to 12. 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. <8> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of styrene, The number average molecular weight is 5000 or more and 8000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. The aforementioned <1> ~ <7> The composite particle according to any one of the preceding items. <9> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of divinylbenzene, The number average molecular weight is 15,000 or more and 30,000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. The aforementioned <1> ~ <8> The composite particle according to any one of the preceding items. <10> the inorganic particles are hollow silica, The average particle size is 400 nm or more and 800 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of methacrylic glycidylates, The number average molecular weight is 1500 or more and 4500 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. The aforementioned <1> ~ <9> The composite particle according to any one of the preceding items.

[0122] <11> The aforementioned <1> ~ <10> A resin composition comprising the composite particles according to any one of the above and a resin. <12> The aforementioned <1> ~ <10> 2. A resin composition for low dielectric materials, comprising the composite particles according to any one of claims 1 to 11 and a resin. <13> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of styrene, The number average molecular weight is 5000 or more and 8000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. Composite particles; Modified polyphenylene ether compounds and <11> or <12> The resin composition for low dielectric materials according to claim 1. <14> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of divinylbenzene, The number average molecular weight is 15,000 or more and 30,000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. Composite particles; Modified polyphenylene ether compounds and <11> or <12> The resin composition for low dielectric materials according to claim 1. <15> the inorganic particles are hollow silica, The average particle size is 400 nm or more and 800 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of methacrylic glycidylates, The number average molecular weight is 1500 or more and 4500 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. Composite particles; Epoxy resin and <11> or <12> The resin composition for low dielectric materials according to claim 1. <16> The aforementioned <1> ~ <10> 2. Use of the composite particles according to any one of the preceding items as a low-dielectric material. <17> The aforementioned <1> ~ <10> 2. Use of a resin composition containing the composite particles according to any one of claims 1 to 11 and a resin as a low dielectric material. <18> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of styrene, The number average molecular weight is 5000 or more and 8000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. The composite particles <16> or <17> Use as a low dielectric material as described in <19> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of divinylbenzene, The number average molecular weight is 15,000 or more and 30,000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. The composite particles <16> or <17> Use as a low dielectric material as described in <20> the inorganic particles are hollow silica, The average particle size is 400 nm or more and 800 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of methacrylic glycidylates, The number average molecular weight is 1500 or more and 4500 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. The composite particles <16> or <17> Use as a low dielectric material as described in

[0123] <21> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of styrene, The number average molecular weight is 5000 or more and 8000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. Composite particles and Modified polyphenylene ether compounds and a composition comprising <17> Use as a low dielectric material as described in <22> the inorganic particles are hollow silica, The average particle size is 1500 nm or more and 2500 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of divinylbenzene, The number average molecular weight is 15,000 or more and 30,000 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. Composite particles and Modified polyphenylene ether compounds and a composition comprising <17> Use as a low dielectric material as described in <23> the inorganic particles are hollow silica, The average particle size is 400 nm or more and 800 nm or less, The porosity is 60% by volume or more and 70% by volume or less, the graft chain is a polymer made of methacrylic glycidylates, The number average molecular weight is 1500 or more and 4500 or less, Graft chain density is 0.1 chains / nm 2 More than 1 chain / nm 2 is as follows: The thickness of the graft chain is 1 nm or more and 10 nm or less. Composite particles and Epoxy resin and a composition comprising <17> Use as a low dielectric material as described in [Example]

[0124] The present invention will be specifically explained below by showing examples, but the present invention is not limited to the following examples.

[0125] [Average particle size of inorganic particles and composite particles] The average particle size of inorganic particles and composite particles was measured by the Coulter counter method using a Multisizer 3 (manufactured by Beckman Coulter, Inc., using a 20 μm aperture tube). That is, the average particle size and the standard deviation of the particle size were determined on a volume basis, and the coefficient of variation was calculated using the following formula. Coefficient of variation (%) = [(standard deviation of particle size) / (average particle size)] x 100 The maximum particle size was defined as the particle size at 99% of the cumulative frequency distribution on a volume basis.

[0126] [Porosity of inorganic particles] The porosity (volume %) of the 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 makes up the particle is used. Porosity of inorganic particles (volume %) = [1 - (measured density / material density of silica particles)] x 100

[0127] [Metal content of inorganic particles] The metal content of the 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, to which 3 mL of concentrated nitric acid, 1 mL of concentrated hydrofluoric acid, and 1 mL of concentrated hydrochloric acid were added, and the mixture was heated to dryness. The residue in the crucible was then diluted with hydrochloric acid and analyzed using an inductively coupled plasma mass spectrometer (Agilent Technologies, product name: Agilent 8900).

[0128] [Specific surface area of ​​particles used in composite particles] The BET specific surface area was used as the specific surface area of ​​the particles used in the composite particles. 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.

[0129] [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 of polymer graft chains (mass%) = "Weight loss rate (mass%) when heating from 40°C to 500°C at a rate of 10°C / min"

[0130] [Graft density of polymer chains in composite particles] Grafting density of polymer chains in composite particles (chains / nm 2 ) is the mass per unit area of ​​the grafted chains on the surface of the composite particle (g / nm 2 ) and the number average molecular weight (Mn) of the grafted chains were measured, and the molecular weight was calculated using the following formula. Graft density (chains / nm 2 ) = [mass of grafted chains per unit area (g / nm2 ) / number average molecular weight of grafted chains × (Avogadro's number)

[0131] The mass of the grafted chains was determined by thermogravimetric (TG) analysis. Specifically, the composite particles 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, which were the raw material for the composite particles. The number average molecular weight of the grafted chains was determined by gel permeation chromatography (GPC) as described below.

[0132] [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 in 2 mL of a 1 mol / L tetrabutylammonium fluoride solution in tetrahydrofuran (Tokyo Chemical Industry Co., Ltd.) for 12 hours to remove the polymer graft chains from the composite particles. The resulting tetrahydrofuran solution containing the dissolved polymer graft chains was reprecipitated using a large amount of methanol, and the solvent was removed and dried to isolate the removed polymer graft chains. The resulting solution 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) (manufactured by Tosoh Corporation) as a column, chloroform as a solvent, at a flow rate of 1.0 mL / min and a column temperature of 40°C, using polystyrene as a converted molecular weight standard.

[0133] [Film thickness of polymer graft chains in composite particles] The film thickness was calculated using the following formula. The polymer density in the formula is the polymer density of the polymer graft chains that are not bonded to the composite particles and are produced simultaneously in the composite particle production process. The polymer density was measured by the pycnometer method in accordance with JIS K 7112.

[0134]

number

[0135] Production Example 1 [Production of silica fine particles] 388.6 g of ion-exchanged water, 200 g of dodecane (Kishida Chemical Co., Ltd.: primary n-dodecane), and 11.4 g of Kotamin 86W (Kao Corporation: containing 28% by mass of stearyl trimethylammonium 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 Coatamin 24P (manufactured by Kao Corporation: containing 27.5% by mass of lauryltrimethylammonium chloride), and 3,120.8 g of ethyl orthosilicate ester (manufactured by Asahi Kasei Wacker Silicones: TEOS999), and the mixture was heated to 40°C with stirring, and then stirred for 10 minutes to obtain preparation solution B. 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 Courtamin 24P were uniformly mixed to obtain Preparation C. The entire amount of Preparation C was added to the entire amount of Preparation B at a constant rate, and then the mixture was stirred at 40°C for 3 hours to obtain a cloudy white liquid D. The resulting cloudy liquid D was then filtered using 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 produce 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 microparticles 1.

[0136] Production Example 2 [Production of silica fine particles] To 2000 g of methanol (Fujifilm Wako Pure Chemical Industries, Ltd., special grade), 91 g of Catiogen TML (Dai-ichi Kogyo Seiyaku Co., Ltd.: containing 30 mass% dodecyltrimethylammonium chloride), 17 g of a 25% aqueous solution of tetramethylammonium hydroxide (Seichem Asia Co., Ltd.: pH 14), and 20 g of hexane (Fujifilm Wako Pure Chemical Industries, Ltd., special grade) were added and stirred to prepare a solution phase containing a hydrophobic organic substance and a hydrophilic organic solvent. 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. To the resulting emulsion, 1500 g of ion-exchanged water was added, and 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.

[0137] Example 1 [Preparation of Composite Particle 1] a) A step of bonding a polymerization initiating group to the particle surface a-1) Introduction of amino groups onto the surface of silica particles 40 g of the silica microparticles obtained in Production 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 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 amino group-introduced silica microparticles.

[0138] a-2) Introduction of polymerization initiation groups onto the surface of amino group-introduced silica particles 40 g of the above amino group-introduced silica microparticles, 200 mL of anhydrous THF, 1 mL of anhydrous triethylamine (Tokyo Chemical Industry Co., Ltd.), and 1 mL of 2-bromoisobutyl bromide (BIBB) (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 particles were washed with THF and anisole, and the polymerization initiator group-introduced silica microparticles with 2-bromoisobutyryl groups introduced as polymerization initiator groups were recovered by centrifugation and stored as anisole-wet polymerization initiator group-introduced silica microparticles.

[0139] b) contacting particles having polymerization initiation groups on their surfaces with a monomer under living radical polymerization conditions; In a 500 mL separable flask, the above-prepared anisole wet product containing 12 g of silica fine particles having polymerization initiation groups, 60 g of anisole, and 180 g of styrene as a monomer were placed and thoroughly stirred, followed by decompression and nitrogen substitution. The temperature was then raised to 90°C, and an acetonitrile solution prepared by stirring 860 mg of Cu(I)Br (Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured into the flask to initiate polymerization. The mixture was then stirred for 30 minutes, and then cooled with ice water and air was bubbled through, followed by adding an excess amount of methanol to quench the reaction. After that, 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). Furthermore, the obtained solid was added with toluene without drying and stored as a toluene solution. The content of 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 chains was 2 nm, and the content of the monomer unit (styrene) in the polymer graft chains was 100% by mass. The structure of the resulting composite particles is shown in FIG.

[0140] Example 2 [Preparation of Composite Particle 2] Step b) contacting particles having polymerization initiation groups on their surfaces with a monomer under living radical polymerization conditions. A 500 mL separable flask was charged with 12 g of silica microparticles having polymerization initiation groups (prepared in step a) of Example 1, 60 g of anisole, and 180 g of divinylbenzene as a monomer, and the contents were thoroughly stirred and then purged with nitrogen under reduced pressure. The flask was then heated to 90°C, and a solution of 860 mg of Cu(I)Br (Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was added to initiate polymerization. After that, 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 silica microparticles grafted with polydivinylbenzene (i.e., composite particles 2). Furthermore, the obtained solid was added with toluene without drying and stored as a toluene solution. The content of polymer graft chains in the obtained composite particle 2 was 2.1 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.

[0141] Example 3 [Preparation of Composite Particle 3] Step b) contacting particles having polymerization initiation 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 the silica particles having polymerization initiation groups prepared in step a) of Example 1 and 240 g of styrene as a monomer, and after thorough stirring, the flask was subjected to reduced pressure and nitrogen substitution. The flask was then heated to 90°C, and an acetonitrile solution prepared by stirring 860 mg of Cu(I)Br (Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured to initiate polymerization. After that, 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 3). Furthermore, the obtained solid was added with toluene without drying and stored as a toluene solution. The content of polymer graft chains in the obtained composite particle 3 was 5.9 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.

[0142] Example 4 [Preparation of Composite Particle 4] Polystyrene-grafted silica fine particles (ie, composite particles 4) were produced in the same manner as in Example 1, except that 40 g of the silica fine particles obtained in Production Example 2 above were used as the silica fine particles. The content of 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.

[0143] Comparative Example 1 [Preparation of Particles 5] (Introduction of vinyl groups onto the surface of silica particles) 40 g of the silica microparticles obtained in Production Example 1 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 Particles 5).

[0144] 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 network analyzer (Agilent Technologies, product name: N5221A) connected to a perturbation method cavity resonator (CP-580) manufactured by Kanto Electronics Application Development Co., Ltd., using the 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. 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 them were within the measurement range (6.75 mm to 36.35 mm from the bottom) to prepare a measurement sample. The 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 packing weight and specific gravity of the composite particles. The relative permittivity and dielectric loss tangent were determined by the difference between the measurement value of an empty Teflon (registered trademark) tube not filled with composite particles and the measurement value of a Teflon (registered trademark) tube filled with composite particles, which was used as the blank.

[0145] [Table 1]

[0146] The abbreviations in the table are as follows: PSt: polystyrene; PDVB: polydivinylbenzene; VTMS: vinyltrimethoxysilane.

[0147] From Table 1, it was demonstrated that the composite particles of the present invention (Examples 1 to 4) have high porosity and are therefore hollow particles. Furthermore, with regard to dielectric properties, it was found that the composite particles of Examples 1 to 4 have smaller relative permittivity values ​​and smaller dielectric loss tangent values ​​than the particles of Comparative Example 1. This is thought to be because the particles of Comparative Example 1 do not have polymer craft chains bonded thereto.

[0148] Examples 11 to 14 and Comparative Example 11 [Preparation of Resin Composition] First, each component other than the composite particles was added to toluene at the blending ratio (parts by mass) shown in Table 2 so that the solids concentration was 60 mass% and mixed. The mixture was stirred at room temperature for 24 hours. Thereafter, the toluene solution of the composite particles was added to the resulting liquid, and the inorganic filler was dispersed using a planetary mixer. This produced a varnish-like resin composition (varnish). Next, the obtained varnish was dried by heating at 80° C. for about 2 to 3 hours to prepare a precursor of a resin molded product. 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).

[0149] Test Example 2 [Dielectric properties of resin molded body] The dielectric properties of the resin molded body were evaluated as follows. The relative permittivity and dielectric loss tangent of the resin molded body were measured at a temperature of 25°C and a measurement frequency of 10 GHz using a network analyzer (Agilent Technologies, product name: N5221A) connected to a perturbation method cavity resonator (Kanto Electronics Application Development Co., Ltd., CP-580) using a cavity resonator perturbation method (CP-MA, permittivity measurement software, Kanto Electronics Application Development Co., Ltd.).

[0150] 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). The cross sections of 50 composite particles were selected from the SEM images, 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 more were judged to have poor dispersibility.

[0151] Table 2 shows the compounding ratios of the resin moldings and the evaluation results.

[0152] [Table 2]

[0153] As described above, in Examples 11 to 14, the composite particles of the present invention (Examples 1 to 4) were used, and therefore the dispersibility of the composite particles was excellent and the dielectric properties were also excellent. On the other hand, in Comparative Example 11, the dispersibility of the particles was significantly inferior to that of the Examples. The reason for the large dispersed particle size in Comparative Example 11 is presumed to be that the particles in Comparative Example 1 did not have organic polymer graft chains, and therefore agglomerates formed in the resin, making them unable to be dispersed.

[0154] 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): SABIC Innovative Plastics, Noryl SA9000 resin, weight average molecular weight = 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 shown in the following formula (2), and R and R in formula (2) are 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), and R 17 and R 18 is a methyl group).

[0155] [ka]

[0156] (Crosslinking curing agent) TAIC: Triallyl isocyanurate (TAIC manufactured by Nippon Kasei 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)

[0157] Synthesis Example 1 [Synthesis of a silane compound having a polymerization initiating group other than a halosulfonyl group] A 500 mL eggplant-shaped flask was charged with 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.). The mixture was cooled on ice until it reached 0°C. While maintaining the ice-cooling, 14.8 mL of 2-bromoisobutyl bromide (BiBB) (Tokyo Chemical Industry Co., Ltd.) was added dropwise and stirred for 4 hours. The solvent was then removed from the liquid phase obtained by filtration using an evaporator. The residue was dried at 50°C for 5 hours to obtain a silane compound bearing a bromoacyl group as a polymerization initiator (this compound will be abbreviated as "APTMS-Br"). This silane compound was used as a silane coupling agent. The synthesis scheme of the above-mentioned APTMS-Br is shown below.

[0158] [ka]

[0159] Example 24 [Preparation of Composite Particle 24] Step a) Binding a polymerization initiating group to the particle surface 15.6 g of silica microparticles 1 (hollow silica microparticles obtained in Production Example 1) 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 above-mentioned APTMS-Br and 0.74 g of ethanol were added to the bag 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 crush mill (manufactured by Iwatani Corporation) and then allowed to stand for 12 hours. Thereafter, the silica fine particles were washed with ethanol, and subsequently collected by suction filtration, and then heated at 110° C. for 1 hour to obtain silica fine particles to which bromoacyl groups, which are polymerization initiation groups, are bonded.

[0160] Step b) contacting particles having polymerization initiation groups on their surfaces with a monomer under living radical polymerization conditions. In a 500 mL separable flask, 3.7 g of the silica fine particles having polymerization initiation groups prepared above, 180 g of anisole, and 60 g of glycidyl methacrylate as a monomer were placed and thoroughly stirred, followed by decompression and nitrogen substitution. The temperature was then raised to 50°C, and an acetonitrile solution prepared by stirring 860 mg of Cu(I)Br (Tokyo Chemical Industry Co., Ltd.) and 2080 mg of pentamethyldiethylenetriamine (Tokyo Chemical Industry Co., Ltd.) in 5 mL of acetonitrile under nitrogen was poured into the flask to initiate polymerization. The mixture was then stirred for 2 minutes, and then cooled with ice water and air was bubbled through, followed by adding an excess amount of methanol to quench the reaction.

[0161] The mixture was then washed with methanol and filtered to remove the solution three times, then washed with toluene and filtered to remove the solution once, and then vacuum dried at 60°C for 12 hours. The resulting solid was crushed in a mortar to obtain a powder. The resulting powder was silica microparticles grafted with polyglycidyl methacrylate, and these microparticles were designated Composite Particles 24.

[0162] 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.

[0163] Example 25 [Preparation of Composite Particles 25] In step b), the mixture was vacuum dried at 60°C for 12 hours, and the resulting solid was crushed in a mortar to obtain a powder, and then further crushed in a jet mill to obtain composite particles 25 in the same manner as in Example 24.

[0164] Example 26 [Preparation of Composite Particles 26] [Production of silica microparticles] In Production Example 1, the stirring speed and temperature were adjusted to obtain emulsion A having a 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 Production Example 1. 2 The hollow silica particles were designated as silica fine particles 3.

[0165] [Preparation of composite particles] Silica microparticles grafted with polyglycidyl methacrylate (i.e., composite particles 26) were obtained in the same manner as in 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 Example 1.

[0166] The content of polymer graft chains in the obtained composite particles 26 was 1.4 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 2 The film thickness of the polymer graft chains was 6 nm, and the content of the monomer unit (glycidyl methacrylate) in the polymer graft chains was 100% by mass.

[0167] The main characteristics of Examples 24 to 26 are summarized in Table 3.

[0168] [Table 3]

[0169] The abbreviations in the table are as follows: PGMA: polyglycidyl methacrylate.

[0170] Examples 27 to 29 [Preparation of resin compositions] First, the epoxy resin, the amine curing agent, and each composite particle were mixed in the blending ratio shown in Table 4. The mixture was dispersed in a planetary mixer to prepare a resin composition (before curing).

[0171] Example 30 [Preparation of resin composition] The epoxy resin, phenol curing agent, and composite particles 26 were mixed in the blending ratio shown in Table 4. The mixture was dispersed in a planetary mixer to prepare a resin composition (before curing).

[0172] Table 4 shows the compounding ratios of the resin moldings and the evaluation results. In Table 4, composite particles with a dispersed particle size 10 times or less than the average particle size of the inorganic particles used are marked with "+", and those with a dispersed particle size greater than 10 times are marked with "-".

[0173] [Table 4]

[0174] 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 using the same method 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.

[0175] In Example 29, the shear viscosity of the resin composition (before curing) and the CTE of the resin molded article (after curing) were evaluated by the following methods. 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.

[0176] [Shear viscosity measurement] The shear viscosity (unit: Pa s) of the resin composition (before curing) was measured using a rheometer (Anton Paar, MCR300). 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 the jig in a uniformly dissolved state.

[0177] The shear viscosity of the resin composition was measured by sweeping the shear rate from low to high between 0.1 (1 / s) and 100 (1 / s), and the shear viscosity value at a shear rate of 32.9 (1 / s) is shown in Table 1. 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.

[0178] Coefficient of Linear Thermal Expansion (CTE) The resin molded body (after curing) was 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 taken in tensile mode with a load of 20 mN and a span distance of 10 mm. The linear thermal expansion coefficient was calculated as the average linear thermal expansion coefficient over a temperature range of 10°C to 30°C. A lower linear thermal expansion coefficient indicates better dimensional stability.

[0179] Details of the main components other than the composite particles in the above examples are as follows: (resin) Bisphenol F epoxy resin (Mitsubishi Chemical Corporation, JER807, epoxy equivalent: 160-175g / eq) Bisphenol A epoxy resin (Mitsubishi Chemical Corporation, JER828, epoxy equivalent: 184-194g / eq)

[0180] (hardening agent) Aromatic amine curing agent (Nippon Kayaku Co., Ltd., KAYAHARD AA, amine equivalent: 64 g / eq) Triazine-containing phenolic resin (DIC, LA7052, hydroxyl equivalent: 120 g / eq) [Industrial Applicability]

[0181] The resin composition containing the composite particles obtained by the production method of the present invention 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 composite particle having a polymer graft chain on the surface of an inorganic particle, the inorganic particles are hollow particles, The inorganic particles have an average particle size of more than 200 nm and not more than 3,000 nm. composite particles.

2. The composite particles according to claim 1 , wherein the porosity of the inorganic particles is 50% by volume or more and 80% by volume or less.

3. The graft density of the polymer graft chains in the composite particles is 0.01 chains / nm ２ The composite particle according to claim 1 or 2, wherein the above-mentioned

4. 3. The composite particle according to claim 1, wherein the polymer graft chain is a polymer composed of one or more monomers selected from the group consisting of styrene-based monomers, nitrile-based monomers, (meth)acrylic-based 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 composite particle according to claim 1 or 2, wherein the inorganic particle is silica.

6. 3. The composite particles according to claim 1, wherein the inorganic particles are silica particles, and the total content of the alkali metal and alkaline earth metal relative to the content of silica in the inorganic particles is 50 ppm by mass or less.

7. 3. The composite particle according to claim 1, wherein the polymer graft chain is provided 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.

8. A resin composition comprising the composite particles according to claim 1 or 2 and a resin.

9. A resin composition for low dielectric materials, comprising the composite particles according to claim 1 or 2 and a resin.

10. A low dielectric resin composition comprising the composite particles according to claim 1 or 2 and a resin.

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