Method for producing composite particles

Abstract

The present invention relates to a method for producing composite particles that each have a polymer graft chain, the method including the following steps, wherein the step 1 is performed in a powder state. (Step 1) A step for reacting inorganic particles with a silane compound that has a polymerization initiation group other than a halosulfonyl group so as to bond the polymerization initiation group to the inorganic particles; and (step 2) a step for graft-polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiation group is bonded. The present invention provides a production method by which composite particles having a graft density equivalent to that of conventional methods which use a solvent when introducing a polymerization initiation group are obtained, the production method having excellent handleability during production.

Description

Method for producing composite particles

[0001] The present invention relates to a method for producing composite particles.

[0002] Conventionally, as a technique for bonding polymer chains to inorganic particles such as metal particles, for example, composite particles have been known in which the surface of the core particles is coated with a polymer layer by radical polymerization in the presence of core particles mixed with a coupling agent having a polymerizable reactive group, a monomer component, and a polymerization initiator (Patent Document 1).It is known that bonding organic polymer chains to inorganic particles can impart various functions to the particles, such as vibration damping and antibacterial properties (Patent Documents 2 and 3).

[0003] However, in the production of composite particles described in Patent Documents 1 and 2, a large amount of solvent is used when introducing polymerization initiator groups, resulting in a small amount of inorganic particles that can be processed per unit volume, and thus hindering production efficiency. Furthermore, reducing the amount of solvent used results in a highly viscous slurry that is difficult to handle. In contrast, in the production of composite particles described in Patent Document 3, a small amount of solvent is used when introducing polymerization initiator groups, and the particles can be handled as a powder even after introduction of the polymerization initiator groups, which is thought to solve the above problem. However, when the inventors examined the technology described in Patent Document 3, they found that the graft density of the polymer graft chains in the technology described in Patent Document 3 was unexpectedly low, leaving room for improvement. A higher graft density of polymer graft chains on the surface of the composite particles has the advantages of better dispersibility of the composite particles and the ability to introduce a larger number of functional molecules.

[0004] JP 2005-120365 A JP 2020-196877 A JP 2010-018535 A

[0005] The present invention relates to the following items [1] to

[11] . [1] A method for producing composite particles having polymer graft chains, comprising the following steps, wherein step 1 is carried out in a powder state: (Step 1) a step of reacting inorganic particles with a silane compound having a polymerization initiation group other than a halosulfonyl group to bond the polymerization initiation group to the inorganic particles; and (Step 2) a step of graft-polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiation group is bonded. [2] Among the components used in step 1, the ratio of the total surface area of ​​the inorganic particles (A [m ]) to the total mass (B [g]) of liquid substances at 25°C and 1 atmospheric pressure is ２ ]) ratio ((A) / (B) [m ２ [3] The manufacturing method according to [1] above, wherein the ratio ((A') / (B)) of the total mass of inorganic particles (A' [g]) to the total mass of substances that are liquid at 25°C and 1 atmospheric pressure (B [g]) among the components used in step 1 is 2 or more. [4] The manufacturing method according to any one of [1] to [3] above, comprising a step of contacting inorganic particles having polymerization initiation groups bonded thereto with a monomer under living radical polymerization conditions. [5] The manufacturing method according to any one of [1] to [3] above, wherein the graft density of polymer graft chains on the surface of the composite particle is 0.001 chains / nm ２ More than 5 chains / nm ２[6] The method for producing a resin composition according to any one of [1] to [4], wherein the amount of the silane compound having a polymerization initiating group other than a halosulfonyl group used is 0.1 parts by mass or more and 100 parts by mass or less per 100 parts by mass of inorganic particles. [7] The method for producing a resin composition according to any one of [1] to [6], wherein the polymerization initiating group is an α-haloacyl group, a haloalkyl group, or a haloalkylphenyl group. [8] The method for producing a resin composition according to any one of [1] to [7], wherein in step 1, one or more selected from the group consisting of ethanol, dichloromethane, toluene, acetone, tetrahydrofuran, methanol, butanol, and butyl cellosolve are further used. [9] The method for producing a resin composition according to any one of [1] to [8], wherein a catalyst is further used in step 1.

[10] The method for producing a resin composition, comprising a step of mixing the composite particles obtained by the method for producing a resin according to any one of [1] to [9] with a resin.

[11] A method for producing composite particles having polymer graft chains, the method comprising the following steps: (Step 1) reacting inorganic particles with a silane compound having a polymerization initiation group other than a halosulfonyl group to bond the polymerization initiation group to the inorganic particles; and (Step 2) graft-polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiation group is bonded. Detailed Description of the Invention

[0006] The present invention relates to a method for producing composite particles having a graft density equivalent to that of conventional methods using a solvent when introducing polymerization initiator groups, and which has excellent handleability during production. According to the present invention, a method for producing composite particles having a graft density equivalent to or higher than that of conventional methods using a solvent when introducing polymerization initiator groups, and which has excellent handleability during production, can be provided.

[0007] The present inventors focused on the type of silane coupling agent used when introducing polymerization initiator groups into inorganic particles. The inventors hypothesized that the silane coupling agent used in Patent Document 1, a compound having a halosulfonyl group, tends to generate radicals more frequently, causing the graft polymerization reaction to proceed too quickly, resulting in a decrease in graft density. Therefore, they investigated various silane coupling agents other than compounds having a halosulfonyl group. They found that by minimizing the amount of liquid components, such as solvents, used to introduce polymerization initiator groups into inorganic particles using such silane coupling agents, not only was it possible to improve handling during production, but also, unexpectedly, to achieve a high graft density.

[0008] <Method for producing composite particles having polymer graft chains> The method for producing composite particles having polymer graft chains of the present invention is a method for producing composite particles having polymer graft chains, comprising the following steps, in which step 1 is carried out in a powder state: (Step 1) a step of reacting inorganic particles with a silane compound having a polymerization initiation group other than a halosulfonyl group to bond the polymerization initiation group to the inorganic particles, and (Step 2) a step of graft polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiation group is bonded.

[0009] In the present invention, "powder" refers to a collection of particles in which no liquid phase can be visually observed, no caking occurs, and the powder has fluidity. "Fluidity" means that the powder satisfies both of the following two conditions: - The powder passes through a funnel (with a bottom outlet diameter of 5 mm) without resistance - The angle of repose is measurable

[0010] In the present invention, the angle of repose of the powder or particles can be measured using a Powder Tester PT-R manufactured by Hosokawa Micron Corporation. In the present invention, the angle of repose of the particles immediately after completion of step 1 is preferably within a range of 25 degrees or more and 65 degrees or less. Therefore, for example, if the angle of repose of the particles immediately after completion of step 1 is within a range of 25 degrees or more and 65 degrees or less, it can be said that step 1 was carried out in a powder state.

[0011] In the present invention, the term "liquid" refers to a state of fluidity in which volume change with pressure change is sufficiently small, and the viscosity at 25°C and 1 atmosphere is preferably 10,000 mPa s or less, more preferably 8,000 mPa s or less, and even more preferably 4,000 mPa s or less. The viscosity is measured for 1 minute at a predetermined rotation speed and a temperature of 25°C using a Brookfield viscometer with a rotor appropriate for the applicable measurement range.

[0012] [Composite Particles] Composite particles in the present invention are inorganic particles having polymer graft chains bonded to the surfaces thereof.

[0013] [Inorganic Particles] Examples of inorganic particles include metal-based particles such as metal oxides, metal oxide salts, metal hydroxides, and metal carbonates, as well as non-metallic particles. For example, the inorganic particles include one or more particles selected from the group consisting of silica, alumina, titania, zirconia, ferrite, magnesia, silica-titania, silicon carbide, silicon nitride, activated carbon, carbon black, carbon nanofibers, carbon nanotubes, calcium carbonate, calcium oxide, barium sulfate, diatomaceous earth, bentonite, perlite, mica, and talc, more preferably one or more particles selected from the group consisting of silicon oxides such as silica, and silicates such as mica and talc, and even more preferably silica.

[0014] In order to increase the reaction rate with a silane compound having a polymerization initiating group other than a halosulfonyl group, the inorganic particle surface may be treated by a known method to increase the amount of hydroxy groups, amino groups, etc. on the inorganic particle surface. The shape of the particles is not particularly limited, and examples thereof include plate-like, granular, needle-like, and fibrous shapes. In this specification, the term "particle" simply refers to particles used in the production of composite particles.

[0015] The size of the inorganic particles is not particularly limited, but from the viewpoint of improving the graft density of the polymer graft chains on the surface of the composite particles, the average particle size is preferably 1 nm or more, more preferably 3 nm or more, even more preferably 10 nm or more, still more preferably 50 nm or more, and still more preferably 100 nm or more, while it is preferably 100 μm or less, more preferably 10 μm or less, still more preferably 1 μm or less, still more preferably 500 nm or less, and still more preferably 300 nm or less.

[0016] The size of the inorganic particles is a value measured by the Coulter counter method using a Multisizer 3 (manufactured by Beckman Coulter, Inc., using a 20 μm aperture tube).

[0017] [Polymer Graft Chain] Examples of the polymer graft chain include homopolymers or copolymers of styrene-based monomers, nitrile-based monomers, (meth)acrylic monomers, unsaturated olefins, conjugated diene-based monomers, etc. Preferred are homopolymers or copolymers of one or more types selected from the group consisting of acrylic acid, methacrylic acid, and derivatives thereof, more preferred are homopolymers or copolymers of one or more types selected from methacrylic acid and derivatives thereof, and even more preferred is polybutyl methacrylate.

[0018] The graft density of the polymer graft chains on the surface of the composite particle is preferably 0.001 chains / nm from the viewpoint of functional expression. ２ or more, more preferably 0.01 chains / nm ２ More preferably, 0.1 chains / nm ２ On the other hand, from the viewpoint of ease of grafting of polymer chains, it is preferable that the number of chains is 5 chains / nm. ２ More preferably, 3 chains / nm or less ２ More preferably, 2 chains / nm ２ More preferably, 1 chain / nm or less ２ The graft density is measured by the method described in the Examples below.

[0019] The number average molecular weight of the polymer graft chains in the composite particles is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more, from the viewpoint of controlling the film thickness of the polymer graft chains. From the same viewpoint, it is preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 200,000 or less. The number average molecular weight of the polymer graft chains is measured by the method described in the Examples below.

[0020] From the viewpoint of functional expression, the glass transition temperature (Tg) of the polymer graft chains in the composite particles is preferably −30° C. or higher, more preferably −10° C. or higher, and even more preferably 10° C. or higher, and from the same viewpoint, it is preferably 80° C. or lower, more preferably 50° C. or lower, and even more preferably 40° C. or lower. The glass transition temperature (Tg) of the polymer graft chains in the composite particles can be controlled by the monomers, molecular weight, and molecular weight distribution used in the production of the composite particles. The glass transition temperature (Tg) is measured by the method described in the Examples below.

[0021] From the viewpoint of functional expression, the film thickness of the polymer graft chain in the composite particle is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. From the same viewpoint, it is preferably 1 μm or less, more preferably 100 nm or less, and even more preferably 40 nm or less. The film thickness of the polymer graft chain is calculated by the method described in the Examples below.

[0022] [Silane Compound Having a Polymerization Initiating Group Other Than a Halosulfonyl Group] In the present invention, the "polymerization initiating group other than a halosulfonyl group" includes an α-haloacyl group, a haloalkyl group, or a haloalkylphenyl group.

[0023] Specific examples of the α-haloacyl group include an α-bromoacyl group and an α-chloroacyl group, and the alkyl group constituting the haloacyl group preferably has 3 to 11 carbon atoms. Specific examples of the haloalkyl group include a bromoalkyl group and a chloroalkyl group, and the alkyl group constituting the haloalkyl group preferably has 3 to 11 carbon atoms. Specific examples of the haloalkylphenyl group include a bromoalkylphenyl group and a chloroalkylphenyl group, and the alkyl group constituting the haloalkylphenyl group preferably has 3 to 11 carbon atoms. As the "polymerization initiating group other than a halosulfonyl group," an α-bromoacyl group is preferred, from the viewpoint that the graft density can be increased by introducing such a polymerization initiating group onto the surface of the inorganic particles.

[0024] A silane compound having a polymerization initiating group other than a halosulfonyl group can be synthesized by reacting a "silane compound" with a "compound having a polymerization initiating group" by a known method.

[0025] For example, as described in Synthesis Example 1 below, a silane compound (APTMS-Br) having a bromoacyl group, which is a polymerization initiation group, can be synthesized by reacting 3-aminopropyltrimethoxysilane with 2-bromoisobutyl bromide.

[0026] In addition to 3-aminopropyltrimethoxysilane, examples of the silane compound that can be used in the present invention include 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethoxysilane, 3-aminopropyldimethoxymethylsilane, [3-(6-aminohexylamino)propyl]trimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-(2-aminoethylamino)propyltriethoxysilane, trimethoxysilane, dimethoxy(methyl)silane, diethoxymethylsilane, triethoxysilane, and tris(trimethylsilyloxy)silane.

[0027] In addition to 2-bromoisobutyl bromide, examples of the compound having the polymerization initiating group that can be used in the present invention include 2-chloroisobutyl chloride, 2-bromopropionyl bromide, 2-chloropropionyl chloride, 2-bromo-2-phenylacetyl bromide, 2-chloro-2-phenylacetyl chloride, allyl 2-bromo-2-methylpropionate, 5-hexene 1-(2-bromo-2-methyl)propionate, and 10-undecenyl 2-bromoisobutyrate.

[0028] As the silane compound having a polymerization initiating group other than a halosulfonyl group, a commercial product available as a silane coupling agent in the field of the present invention can also be used, and examples thereof include 3-(trimethoxysilyl)propyl bromo-2-methylpropanoate.

[0029] [Method for producing composite particles] Composite particles can be obtained by bonding polymer graft chains to the particle surfaces. The method for bonding polymer graft chains to the particle surfaces is not particularly limited as long as it is a method that can graft polymer chains, but a grafting from method in which polymer graft chains are polymerized from polymerization initiation points on the particle surfaces is preferred.

[0030] 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.

[0031] 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.

[0032] More specifically, an example of a method for producing composite particles includes the following steps 1 and 2.

[0033] [Step 1] Step 1 is a step of reacting inorganic particles with a silane compound having a polymerization initiating group other than a halosulfonyl group to bond the polymerization initiating group to the inorganic particles. Specifically, inorganic particles, a silane compound having a polymerization initiating group other than a halosulfonyl group, and optionally a catalyst, solvent, etc. are added and mixed. More preferably, when inorganic particles and a catalyst are used, a silane compound having a polymerization initiating group other than a halosulfonyl group and optionally a solvent are added to a mixture of the inorganic particles and catalyst, and then mixed uniformly. The reaction temperature during the reaction of the silane compound with the inorganic particles is preferably 25°C to 250°C, more preferably 150°C or less, and even more preferably 120°C or less.

[0034] The amount of the silane compound having a polymerization initiating group other than a halosulfonyl group used relative to 100 parts by mass of inorganic particles is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, from the viewpoint of the surface modification efficiency of the inorganic particles, while from the viewpoint of suppressing the reaction between the silane compounds, 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.

[0035] The reaction between the silane compound and the inorganic particles is preferably carried out in a powder state in step 1. This is because it is possible to increase the amount of inorganic particles that can be treated per unit volume, thereby improving production efficiency. To carry out step 1 in a powder state, for example, it is sufficient to use as little of a substance, such as a solvent, that is liquid at 25°C and 1 atmosphere as possible.

[0036] In the present invention, the phrase "using as little substance as possible that is liquid at 25°C and 1 atmospheric pressure" refers to the ratio of the total surface area of ​​inorganic particles (A [m]) to the total mass (B [g]) of substances that are liquid at 25°C and 1 atmospheric pressure among the components used in step 1. ２ ]) ratio ((A) / (B) [m ２ / g]) is 20 or more.

[0037] Here, from the viewpoint of carrying out step 1 in a powder state and improving the graft density of the polymer graft chains on the surface of the composite particles, (A) / (B) [m ２ / g] is 20 or more, preferably 45 or more, more preferably 50 or more, and even more preferably 70 or more. On the other hand, from the viewpoint of the surface modification efficiency of the inorganic particles, (A) / (B) [m ２ / g] is preferably 1,000 or less, more preferably 800 or less, even more preferably 700 or less, and still more preferably 500 or less. The total surface area of ​​the inorganic particles can be determined by the method described in the examples below.

[0038] Among the components used in step 1, substances that are liquid at 25°C and 1 atmospheric pressure include solvents and catalysts used in the field of the present invention that are liquid at 25°C and 1 atmospheric pressure, and silane compounds having a polymerization initiating group other than a halosulfonyl group.

[0039] Examples of solvents that can be used in step 1 include solvents containing an organic solvent and / or water, and more specifically, include water in addition to organic solvents such as ethanol, dichloromethane, toluene, acetone, tetrahydrofuran, methanol, butanol, butyl cellosolve, etc. Among these, from the viewpoint of improving the dispersibility of the silane coupling agent with the inorganic particles and increasing the graft density of the polymer graft chains on the surfaces of the composite particles, solvents containing an organic solvent are preferred, and specifically, solvents containing ethanol, toluene, tetrahydrofuran, and methanol are preferred, solvents containing ethanol, toluene, and tetrahydrofuran are more preferred, and solvents containing ethanol are even more preferred.

[0040] The mass ratio of the organic solvent to the silane coupling agent is preferably 0.1 or more, more preferably 0.5 or more, even more preferably 1 or more, even more preferably 2 or more, and is preferably 10 or less, more preferably 8 or less, and more preferably 4 or less, relative to 1 part of the silane coupling agent, from the viewpoint of carrying out step 1 in a powder state and from the viewpoint of improving the graft density of the polymer graft chains on the surface of the composite particles.

[0041] In addition, from the viewpoint of improving the reactivity of the silane coupling agent with the inorganic particles and increasing the graft density of the polymer graft chains on the surface of the composite particles, the solvent in step 1 preferably contains water.

[0042] The mass ratio of water to silane coupling agent is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, even more preferably 0.2 or more, and preferably 1 or less, more preferably 0.5 or less, and more preferably 0.3 or less, relative to 1 part of silane coupling agent, from the viewpoint of carrying out step 1 in a powder state and from the viewpoint of improving the graft density of the polymer graft chains on the surface of the composite particles.

[0043] When an organic solvent and water are used in combination, the mass ratio of alcohol and water to silane coupling agent is preferably 11 or less, more preferably 8.5 or less, and even more preferably 4.3 or less, relative to 1 part of silane coupling agent, from the viewpoint of carrying out step 1 in a powder state.

[0044] Examples of the catalyst that can be used in step 1 include acids (e.g., acetic acid, trifluoroacetic acid, etc.), bases (e.g., ammonia, triethylamine, diethylamine, etc.), transition metals (e.g., Ti, Ni, Sn, etc.), and metals containing transition metals. Among these, from the viewpoints of good dispersibility with inorganic particles and improving the graft density of polymer graft chains on the surfaces of composite particles, bases are preferred, secondary amines and / or tertiary amines are more preferred, and tertiary amines are even more preferred.

[0045] The secondary amine is an ammonia in which two hydrogen atoms have been substituted with hydrocarbon groups, and in the present invention, preferred examples thereof include dipropylamine, diisopropylamine, dibutylamine, etc. The tertiary amine is an ammonia in which all hydrogen atoms have been substituted with hydrocarbon groups, and preferred examples thereof include diethylmethylamine, triethylamine, ethyldiisopropylamine, tripropylamine, tributylamine, etc.

[0046] A catalyst may or may not be used in step 1. When a catalyst is used, the amount of the catalyst to be blended may be the amount usually used in the field of the present invention. ２From the viewpoint of the surface modification efficiency of the inorganic particles, the amount of silane compound is preferably 0.1 mol or more, more preferably 0.5 mol or more, and even more preferably 1 mol or more, relative to the total amount of silane compound, while from the viewpoint of suppressing the reaction between the silane compounds, the amount of silane compound is preferably 1,000 mol or less, more preferably 100 mol or less, and even more preferably 10 mol or less.

[0047] Furthermore, from the viewpoint of improving the graft density of polymer graft chains on the surface of the composite particles, the ratio ((A') / (B)) of the total mass of inorganic particles (A' [g]) to the total mass of substances that are liquid at 25°C and 1 atmosphere (B [g]) is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, and even more preferably 10 or more. On the other hand, from the viewpoint of the surface modification efficiency of the inorganic particles, (A') / (B) is preferably 100 or less, more preferably 80 or less, and even more preferably 60 or less. Furthermore, the total surface area of ​​the inorganic particles (A [m ２ Regarding the relationship between (A') / (B) and (A') / (B), it is more preferable that the value of (A') / (B) is within the above range and further satisfies log(A)≧−6.2log((A') / (B))+2.35, from the viewpoint of carrying out step 1 in a powder state.

[0048] After the reaction between the silane compound and the inorganic particles, unreacted components are removed to obtain inorganic particles having polymerization initiation groups other than halosulfonyl groups bonded to their surfaces.

[0049] [Step 2] In Step 2, the monomer is graft polymerized in the presence of inorganic particles to which polymerization initiating groups are bonded. Step 2 can be preferably carried out under known conditions for living radical polymerization. In this specification, "under living radical polymerization conditions" means employing polymerization conditions appropriately selected by a person skilled in the art to ensure that living radical polymerization starting from the polymerization initiating groups formed on the surfaces of the inorganic particles to which polymerization initiating groups are bonded proceeds reliably and satisfactorily.

[0050] Examples of the monomer used in step 2 include styrene-based monomers, nitrile-based monomers, (meth)acrylic-based monomers, unsaturated olefins, and conjugated diene-based monomers. Other monomers having specific groups in their side chains can also be used. Specific examples include butyl methacrylate, butyl acrylate, ethyl methacrylate, ethyl acrylate, methyl methacrylate, methyl acrylate, acrylamide, acrylonitrile, 4-benzoylphenyl acrylate, benzyl methacrylate, cyclohexyl methacrylate, N,N-dimethylmethacrylamide, dodecyl acrylate, dodecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, n-hexyl methacrylate, methacrylamide, methacrylic acid, 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, sodium p-styrenesulfonate, and vinylbenzyl chloride.

[0051] The amount of the monomer used in step 2 is determined based on the surface area of ​​the inorganic particles to which the polymerization initiation groups are bonded, 1 m ２ From the viewpoint of polymer introduction efficiency, the amount of the monomer is preferably 0.00001 mol or more, more preferably 0.0001 mol or more, and even more preferably 0.001 mol or more, relative to the unit specific surface area of ​​the inorganic particles to which the polymerization initiation groups are bonded. On the other hand, from the viewpoint of polymerization control, the amount of the monomer is preferably 10 mol or less, more preferably 1 mol or less, and even more preferably 0.1 mol or less, relative to the unit specific surface area of ​​the inorganic particles to which the polymerization initiation groups are bonded.

[0052] The graft polymerization is carried out using a copper halide such as copper bromide or copper chloride as a catalyst. There are no particular limitations on the ligand complex for the copper halide. Examples include tris(2-(dimethylamino)ethyl)amine, N,N,N",N"-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetraamine, 1,4,8,11-tetramethyl-1,4,8,11-azacyclotetradecane, and bipyridine. The amount of copper halide as a catalyst is usually 0.1 to 1.0 part by mass per 100 parts by mass of the monomer.

[0053] The solvent used during polymerization is not particularly limited as long as it can dissolve the monomers, and examples thereof include anisole, toluene, tetrahydrofuran, acetonitrile, methanol, 2-propanol, hexane, octane, dodecane, and 2,2,2-trifluoroethanol.

[0054] The reaction temperature is usually 30 to 200° C., preferably 50 to 150° C. After the graft polymerization, it is preferable to remove unreacted monomers and free polymers that have not been bonded to the inorganic particles by a known method.

[0055] <Resin Composition and Method for Producing Resin Composition> The resin composition of the present invention contains composite particles obtained by the above-described production method and a resin. [Resin] As the resin, a thermoplastic resin is preferred from the viewpoint of processability, and a thermosetting resin is preferred from the viewpoint of heat resistance. Examples of thermoplastic resins include polyolefin resins, polyester resins, polyamide resins, ABS resins, polystyrene resins, polycarbonate resins, vinyl chloride resins, and acrylic resins. Among these, from the viewpoint of ease of handling of the resulting resin composition, such as moldability, one or more resins selected from the group consisting of polyolefin resins, polyamide resins, and ABS resins are preferred, more preferably one or more resins selected from the group consisting of polyolefin resins, and even more preferably polypropylene resin. The mass average molecular weight of the thermoplastic resin is not particularly limited, but a resin of 5,000 to 500,000 can be used.

[0056] Examples of thermosetting resins include polyurethane resins, urea resins, phenolic resin foams, unsaturated polyester resins, alkyd resins, melamine resins, epoxy resins, silicone resins, and modified polyphenylene ether resins. Among these, modified polyphenylene ether resins are preferred due to 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. The weight average molecular weight of the thermosetting resin is not particularly limited, but can be from 100 to 500,000.

[0057] The amount of resin in the resin composition of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more from the viewpoint of moldability. On the other hand, from the viewpoint of functional expression, it is preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. When two or more types of resins are blended, the amount is the total amount of each resin.

[0058] The amount of composite particles in the resin composition of the present invention is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoint of functional expression. On the other hand, from the viewpoint of dispersibility of the composite particles in the resin, it is preferably 75% by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less. When two or more types of composite particles are contained, the amount is the total amount of each composite particle.

[0059] The resin composition of the present invention may contain, as components other than those described above, chain extenders, plasticizers, organic crystal nucleating agents, inorganic crystal nucleating agents, hydrolysis inhibitors, flame retardants, antioxidants, lubricants such as hydrocarbon waxes and anionic surfactants, ultraviolet absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, mildew inhibitors, antibacterial agents, foaming agents, other polymeric materials, and the like.

[0060] [Method for Producing Resin Composition] The resin composition of the present invention can be produced by a production method including a step of mixing the composite particles obtained by the above-mentioned production method with a resin. For example, a production method including a step of melt-kneading the resin and the composite particles can be used. For melt-kneading, a known kneader such as an internal kneader, a single-screw or twin-screw extruder, or an open-roll kneader can be used. After melt-kneading, the melt-kneaded mixture may be dried or cooled according to a known method. Alternatively, the raw materials may be uniformly mixed in advance using a Henschel mixer, a super mixer, or the like, before being subjected to melt-kneading. The melt-kneading temperature and melt-kneading time are not necessarily set depending on the type of raw materials used, but are preferably 170 to 240°C and 15 to 900 seconds.

[0061] In relation to the above-described embodiments, the present invention further discloses the following methods for producing composite particles, methods for producing resin compositions, and resin compositions. [1] A method for producing composite particles having polymer graft chains, comprising the following steps, in which step 1 is carried out in a powder state: (Step 1) A step of reacting inorganic particles with a silane compound having a polymerization initiation group other than a halosulfonyl group to bond the polymerization initiation group to the inorganic particles; and (Step 2) A step of graft-polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiation group is bonded.

[0062] [2] The manufacturing method according to [1], wherein the powder is a collection of particles, a liquid phase cannot be confirmed by visual observation, caking does not occur, and the powder has fluidity. [3] The manufacturing method according to [1] or [2], wherein the fluidity means that the powder passes through a funnel (with a lower outlet diameter of 5 mm) without resistance and has an angle of repose of 25 degrees or more and 65 degrees or less. [4] The manufacturing method according to [1] or [2], wherein the ratio of the total surface area of ​​inorganic particles (A [m ]) to the total mass (B [g]) of liquid substances at 25°C and 1 atmosphere among the components used in step 1 is ２ ]) ratio ((A) / (B) [m ２ [5] The method according to any one of [1] to [3], wherein the (A) / (B) [m ２[6] The method according to any one of [1] to [4], wherein the (A) / (B) [m ２ [7] The method according to any one of [1] to [5], wherein the (A) / (B) [m ２ [1] The manufacturing method according to any one of [1] to [6], wherein the ratio ((A') / (B)) of the total mass of inorganic particles (A' [g]) to the total mass of substances (B [g]) that are liquid at 25°C and 1 atmosphere among the components used in step 1 is 2 or more and 100 or less.

[10] The manufacturing method according to any one of [1] to [9], wherein the ratio (A') / (B) is 3 or more and 60 or less.

[11] The manufacturing method according to any one of [1] to

[10] , wherein the (A), (B), and (A') satisfy the following formula: log(A)≧-6.2log((A') / (B))+2.35

[11] The manufacturing method according to any one of [1] to

[10] , wherein the inorganic particles have an average particle size of 1 nm or more and 100 μm or less.

[12] The manufacturing method according to any one of [1] to

[11] , wherein the inorganic particles have an average particle size of 3 nm or more and 10 μm or less.

[13] The manufacturing method according to any one of [1] to

[12] , wherein the inorganic particles have an average particle size of 50 nm or more and 1 μm or less.

[14] The manufacturing method according to any one of [1] to

[13] , wherein the inorganic particles have an average particle size of 100 nm or more and 500 nm or less.

[15] The manufacturing method according to any one of [1] to

[14] , wherein a catalyst is further used in step 1.

[16] The manufacturing method according to any one of [1] to

[14] , wherein the catalyst is triethylamine, and the amount of triethylamine added is such that the surface area of ​​the inorganic particles is 1 nm ２

[15] The production method according to

[15] , wherein the content by mass of the organic solvent relative to the silane coupling agent is 0.1 mol or more and 1,000 mol or less.

[17] The production method according to any of [1] to

[16] , wherein a solvent further containing an organic solvent and / or water is used in step 1.

[18] The production method according to

[17] , wherein the organic solvent contains one or more selected from ethanol, dichloromethane, toluene, acetone, tetrahydrofuran, methanol, butanol, and butyl cellosolve, preferably one or more selected from ethanol, toluene, tetrahydrofuran, and methanol, more preferably one or more selected from ethanol, toluene, and tetrahydrofuran, and even more preferably ethanol.

[19] The production method according to

[17] or

[18] , wherein the content by mass ratio of the organic solvent to the silane coupling agent is 0.1 or more and 10 or less, preferably 0.5 or more and 8 or less, more preferably 1 or more and 4 or less, and even more preferably 2 or more and 4 or less.

[20] The method according to

[17] , wherein the organic solvent is ethanol, and the mass ratio of ethanol to the silane coupling agent is 0.1 to 10, preferably 2 to 4, relative to 1 silane coupling agent.

[21] The method according to any one of

[17] to

[20] , wherein the mass ratio of water to the silane coupling agent is 0.01 to 1, preferably 0.05 to 0.5, more preferably 0.1 to 0.3, and even more preferably 0.2 to 0.3.

[22] The method according to any one of

[17] to

[21] , wherein, when an organic solvent alcohol and water are used in combination, the mass ratio of alcohol and water to the silane coupling agent is 11 or less, preferably 8.5 or less, and more preferably 4.3 or less.

[23] The method according to any one of [1] to

[22] , wherein the amount of the silane compound having a polymerization initiating group other than a halosulfonyl group used is 0.1 parts by mass or more and 100 parts by mass or less, preferably 0.5 parts by mass or more and 50 parts by mass or less, and more preferably 1.0 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of inorganic particles.

[24] The method according to any one of [1] to

[23] , comprising a step of contacting inorganic particles having a polymerization initiating group bonded thereto with a monomer under living radical polymerization conditions.

[25] The graft density of the polymer graft chains on the surface of the composite particle is 0.001 chains / nm. ２ More than 5 chains / nm ２ preferably 0.01 chains / nm or less. ２ 3 chains / nm ２ More preferably 0.1 chains / nm or less. ２ 2 chains / nm ２ More preferably, it is 0.1 chains / nm or less. ２ 1 chain / nm ２The manufacturing method according to any one of [1] to

[24] , wherein the composite particles obtained by the manufacturing method according to any one of [1] to

[25] are mixed with a resin.

[27] The manufacturing method according to

[26] , wherein the resin is a thermoplastic resin.

[28] The manufacturing method according to

[27] , wherein the thermoplastic resin is one or more selected from polyolefin resin, polyester resin, polyamide resin, ABS resin, polystyrene resin, polycarbonate resin, vinyl chloride resin, and acrylic resin.

[29] The manufacturing method according to

[27] or

[28] , wherein the thermoplastic resin is a polypropylene resin having a mass average molecular weight of 5,000 or more and 500,000 or less.

[30] The manufacturing method according to

[26] , wherein the resin is a thermosetting resin.

[31] The method according to

[30] , wherein the thermosetting resin is one or more selected from polyurethane resin, urea resin, phenolic resin foam, unsaturated polyester resin, alkyd resin, melamine resin, epoxy resin, silicone resin, and modified polyphenylene ether resin.

[32] The method according to

[30] , wherein the thermosetting resin is modified polyphenylene ether resin.

[33] A method for producing composite particles having polymer graft chains, comprising the following steps, wherein step 1 is performed in a powder state, the method comprising: a resin; and a resin composition. (Step 1) a step of reacting inorganic particles with a silane compound having a polymerization initiating group other than a halosulfonyl group to bond the polymerization initiating group to the inorganic particles, and (Step 2) a step of graft polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiating group is bonded.

[34] A method for producing composite particles having polymer graft chains, comprising: (Step 1) a step of reacting inorganic particles with a silane compound having a polymerization initiating group other than a halosulfonyl group to bond the polymerization initiating group to the inorganic particles, and (Step 2) a step of graft polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiating group is bonded, wherein, among the components used in Step 1, the ratio of the total surface area of ​​the inorganic particles (A [m]) to the total mass (B [g]) of liquid substances at 25°C and 1 atmospheric pressure is ２ ]) ratio ((A) / (B) [m ２ / g]) is 20 or more.

[35] A resin composition comprising a resin and composite particles obtained by the method for producing composite particles.

[36] A resin composition comprising a composite particle obtained by the method for producing composite particles, wherein the polymer graft chain is obtained by a production method including step 1 of reacting inorganic particles with a silane compound having a polymerization initiating group other than a halosulfonyl group to bond the polymerization initiating group to the inorganic particles, and step 2 of graft polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiating group is bonded, wherein step 1 is performed in a powder state.

[36] A resin composition comprising the composite particle according to

[35] above and a polypropylene resin having a mass average molecular weight of 5,000 or more and 500,000 or less.

[37] A resin composition comprising the composite particle according to

[35] above and a modified polyphenylene ether resin.

[0063] The present invention will be specifically explained below by showing examples, but the present invention is not limited to the following examples.

[0064] [Graft Density of Polymer Graft Chains on Composite Particle Surface] The graft density of polymer graft chains on the composite particle surface (chains / nm ２ ) is the mass per unit area of ​​the grafted chains bonded to the surface of the composite particle (g / nm ２ The graft density (chains / nm) was calculated by the following formula: ２ ) = [mass of grafted chains per unit area (g / nm ２ ) / number average molecular weight of grafted chains × (Avogadro's number)

[0065] Here, the mass of the grafted chains was determined by thermal gravitational loss (TG) measurements. More specifically, the composite particles to be measured were heated in air from 40°C to 500°C at a rate of 10°C / min, and the weight loss rate was measured. Furthermore, the "mass of grafted chains per unit area" was calculated from the specific surface area of ​​the inorganic particles that were the raw material for the composite particles to be measured. The number-average molecular weight of the grafted chains was determined by gel permeation chromatography (GPC) as shown below.

[0066] [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 measured by measuring the number-average molecular weight of polymer chains that were not bonded to the composite particles and were simultaneously produced during the composite particle production process. The number-average molecular weight was measured by gel permeation chromatography (GPC) using a TSKgel GMHHR-H + GMHHR-H (cation) (manufactured by Tosoh Corporation) column, chloroform as the solvent, a flow rate of 1.0 mL / min, a column temperature of 40°C, and polystyrene as the molecular weight standard.

[0067] [Method for measuring the specific surface area of ​​inorganic particles and calculating the total surface area] The specific surface area of ​​inorganic particles was measured by the method of JIS Z 8833 (corresponding international standard: ISO 14488:2007). That is, the amount of adsorbed gas [cm 3 ] was calculated by the gas adsorption method according to JIS Z 8830:2001 (corresponding international standard: ISO 9277:2010) for particle samples collected in accordance with JIS Z 8833. ３ The specific surface area of ​​the inorganic particles was calculated from the adsorption isotherm based on the so-called BET theory using [[(2-hydroxybenzoate)-1-hydroxybenzoate / g]]. In this specification, the value obtained by the static volume method using a BELSORP-mini II manufactured by BEL Japan Co., Ltd. was used. The total surface area was calculated as the product of the mass of the inorganic particles used and the specific surface area of ​​the inorganic particles.

[0068] [Glass transition temperature of polymer graft chains in composite particles] The glass transition temperature was measured according to the method of JIS K 7121. That is, using a differential scanning calorimeter (DSC7020 manufactured by Hitachi High-Tech Science Corporation), the composite particles were heated from 40°C to 200°C at a rate of 10°C / min, and the heat capacity was measured. The midpoint glass transition temperature Tmg (°C) was determined as the temperature at the point in the DSC thermogram where a line equidistant in the vertical direction from the extended line of each baseline intersects with the curve representing the stepwise change in the glass transition.

[0069] [Film Thickness of Polymer Graft Chains in Composite Particles] The film thickness was calculated using the following formula. The polymer density in the formula was the polymer density of the polymer graft chains that were not bonded to the composite particles and were simultaneously produced in the process of producing the composite particles. The polymer density was measured using a pycnometer method in accordance with JIS K 7112.

[0070]

[0071] [Angle of Repose of Composite Particles] The angle of repose of the composite particles was measured using a powder tester (PT-R, manufactured by Hosokawa Micron Corporation).

[0072] Synthesis Example 1 [Synthesis of a silane compound having a polymerization initiator group other than a halosulfonyl group] 17.9 g of 3-aminopropyltrimethoxysilane (KBM-903, Shin-Etsu Chemical Co., Ltd.), 100 mL of anhydrous tetrahydrofuran (THF), and 16.8 mL of anhydrous triethylamine (Tokyo Chemical Industry Co., Ltd.) were added to a 500 mL eggplant-shaped flask. This mixture was ice-cooled, and when it reached 0°C, 14.8 mL of 2-bromoisobutyl bromide (BiBB) (Tokyo Chemical Industry Co., Ltd.) was added dropwise while maintaining the ice cooling, and the mixture was stirred for 4 hours. The solvent was then removed from the liquid phase obtained after filtration using an evaporator. The residue was dried at 50°C for 5 hours to obtain a silane compound having a bromoacyl group as a polymerization initiator group (this compound will be abbreviated as "APTMS-Br"). This silane compound was used as a silane coupling agent. The synthesis scheme for the above-mentioned APTMS-Br is shown below.

[0073]

[0074] Example 1 [Step 1] Silica fine particles (manufactured by Admatechs Co., Ltd., SO-C2, average particle size 500 nm, specific surface area 5.5 m) were placed in a plastic bag. ２50 g of silica (100%) (1000 kJ / g) and 0.23 g of anhydrous triethylamine as a catalyst were added and mixed by hand from the outside of the bag at room temperature for 5 minutes. 0.74 g of APTMS-Br was added and mixed by hand from the outside of the bag at room temperature (approximately 25°C, same below). These were mixed at room temperature for 5 minutes using a crushing mill (manufactured by Iwatani Corporation) and then allowed to stand for 12 hours. The components that were liquid at 25°C and 1 atmosphere in Step 1 were APTMS-Br and anhydrous triethylamine. Visual observation of Step 1 revealed that the system remained in a powder state throughout Step 1. The silica microparticles were then washed with ethanol, recovered by centrifugation, and heated at 110°C for 1 hour to obtain silica microparticles to which bromoacyl groups, the polymerization initiator groups, were bonded.

[0075] [Step 2] 6 g of the above particles having polymerization initiator groups bonded thereto, 30 mL of anisole (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and 90 g of the monomer butyl methacrylate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were placed in a 500 mL separable flask, heated to 80° C., thoroughly stirred, and then nitrogen bubbling was performed for 1 hour. Separately, an anisole solution was prepared by stirring 431 mg of Cu(I)Br (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1,040 mg of pentamethyldiethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) in 2 mL of anisole.

[0076] Next, the entire amount of this anisole solution was poured into the flask to initiate living radical polymerization. That is, stirring was continued at 80°C for 10 minutes. After that, the mixture was washed with methanol, and the silica microparticles grafted with polybutyl methacrylate were recovered by a centrifuge. The graft density on the surface of the obtained silica microparticles was 0.30 chains / nm. ２ The number average molecular weight of the grafted chains was 33,000.

[0077] Example 2 [Step 1] Silica fine particles (manufactured by Admatechs Co., Ltd., SO-C2, average particle size 500 nm, specific surface area 5.5 m) were placed in a plastic bag. ２50 g of ethanol (1000 kJ / g) and 0.23 g of anhydrous triethylamine were added and mixed by hand from the outside of the bag at room temperature for 5 minutes. 0.74 g of APTMS-Br and 0.74 g of ethanol were added and mixed by hand from the outside of the bag at room temperature for 5 minutes. The same process as in Example 1 was then carried out to obtain silica microparticles with polymerization initiator groups bonded to them. In this example, a small amount of ethanol was added as a solvent, but the system was in a powder state in Step 1.

[0078] [Step 2] 6 g of the above particles having polymerization initiator groups bonded thereto, 30 mL of anisole (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and 90 g of the monomer butyl methacrylate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were placed in a 500 mL separable flask, heated to 80° C., thoroughly stirred, and then nitrogen bubbling was performed for 1 hour. Next, the entire amount of the anisole solution was poured into the flask to initiate living radical polymerization in the same manner as in Example 1, thereby obtaining silica microparticles having graft chains of polymethacrylic acid.

[0079] Example 3: The silica fine particles were replaced with other silica fine particles (manufactured by Admatechs Co., Ltd., SO-C1, average particle size 200 nm, specific surface area 17.0 m ２ Silica fine particles having polymethacrylic acid graft chains were obtained in the same manner as in Example 1, except that the amount of the silane coupling agent and catalyst was changed to the amounts shown in Table 1. Since no solvent was used in this example, the system in step 1 was in a powder state.

[0080] Example 4: Silica fine particles were replaced with other silica fine particles (Aerosil 200, manufactured by Degussa, average particle size 12 nm, specific surface area 200 m ２ Silica fine particles having polymethacrylic acid graft chains were obtained in the same manner as in Example 1, except that the amount of the silane coupling agent and catalyst was changed to the amounts shown in Table 1. Since no solvent was used in this example, the system in step 1 was in a powder state.

[0081] Example 5 Silica microparticles having graft chains of polymethacrylic acid were obtained in the same manner as in Example 2, except that the silane coupling agent was changed to another silane coupling agent (Tokyo Chemical Industry Co., Ltd., 2-bromo-2-methylpropanoate 3-(trimethoxysilyl)propyl (abbreviated as "PTMS-Br")) bonded with a bromoacyl group, which is a polymerization initiator group, and the amounts of the silane coupling agent and catalyst were changed to those shown in Table 1. Since no solvent was used in this example, the system was in a powder state in step 1. The structure of PTMS-Br is shown below.

[0082]

[0083] Example 6 Silica microparticles having polymethacrylic acid graft chains were obtained in the same manner as in Example 2, except that the amount of ethanol used was changed to the amount shown in Table 1. In this example, a small amount of ethanol was added as a solvent, but the system in step 1 was in a powder state.

[0084] Example 7: The silica fine particles were replaced with other silica fine particles (manufactured by Admatechs Co., Ltd., SO-C1, average particle size 200 nm, specific surface area 17.0 m ２ Silica microparticles having polymethacrylic acid graft chains were obtained in the same manner as in Example 2, except that the amount of ethanol was changed to 1 / g, the amounts of the silane coupling agent and catalyst were changed to those shown in Table 1, water was added in addition to ethanol as the solvent, and the amounts of the silane coupling agent and catalyst were changed to those shown in Table 1. In this example, trace amounts of ethanol and water were added as solvents, but the system in step 1 was in a powder state.

[0085] Comparative Example 1 Silica nanoparticles (Degussa, Aerosil 200, average particle size 12 nm, specific surface area 200 m ２ 8.0 g of silica nanoparticles (Ts-Cl / g) was placed in a three-neck flask, and the atmosphere inside the flask was replaced with nitrogen. While stirring the silica nanoparticles, 3.6 g of 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (hereinafter abbreviated as "Ts-Cl") was added dropwise. After the dropwise addition was completed, the mixture was stirred and reacted at 110°C for 24 hours. Next, the pressure inside the flask was reduced to remove any unreacted material.

[0086] Thereafter, the mixture was dried under reduced pressure in a light-shielded room temperature environment to obtain silica particles having chlorosulfonyl groups, which are polymerization initiator groups. In this comparative example (corresponding to step 1 in the present invention), the system was in a powder state during the step of obtaining inorganic particles having polymerization initiator groups bonded thereto. Note that Ts-Cl is a halosulfonyl group, which is a chlorosulfonyl group (-SO ２ It is a type of silane coupling agent having a silane group (C1).

[0087] 2.0 g of silica particles with chlorosulfonyl groups introduced, 2.0 g of 4-vinylbenzyl chloride, 0.7 g of sparteine, and 0.1 g of copper bromide were placed in a three-neck flask, and the atmosphere inside the flask was replaced with nitrogen. The mixture was allowed to react at 60°C for 24 hours while stirring. Tetrahydrofuran was added to the reaction product, which was then centrifuged and the supernatant was discarded. The resulting solid was dried under reduced pressure to obtain silica particles with polyvinylbenzyl chloride graft chains.

[0088] Reference Example 1 Silica microparticles having polymethacrylic acid graft chains were obtained in the same manner as in Example 2, except that the amount of ethanol used as the solvent in step 1 was changed to 200 g. Since a solvent was used in this reference example, the system was in a liquid state in step 1.

[0089] Reference Example 2 Silica microparticles having polymethacrylic acid graft chains were obtained in the same manner as in Example 2, except that the amount of ethanol used as the solvent in step 1 was changed to 21.6 g. In this reference example, because a solvent was used, the system was in a slurry state in step 1. Therefore, the viscosity of the mixture was high, and it took considerably longer than in Example 2 to uniformly mix the entire mixture.

[0090] Example 8 Silica fine particles having polymethacrylic acid graft chains were obtained in the same manner as in Example 1, except that the amount of silane coupling agent was changed to the amount shown in Table 3. Since no solvent was used in this example, the system was in a powder state in step 1.

[0091] Example 9 Silica fine particles having polymethacrylic acid graft chains were obtained in the same manner as in Example 3, except that the amount of silane coupling agent was changed to the amount shown in Table 3. Since no solvent was used in this example, the system was in a powder state in step 1.

[0092] Example 10 Silica microparticles having polystyrene graft chains were obtained in the same manner as in Example 6, except that the monomer was changed from butyl methacrylate to styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) In this example, a small amount of ethanol was added as a solvent, but the system in step 1 was in a powder state.

[0093] Example 11 Silica microparticles having polystyrene graft chains were obtained in the same manner as in Example 10, except that the mixing device in step 1 was changed from a crush miller to a Super Mixer (manufactured by Kawata Co., Ltd.) In this example, a small amount of ethanol was added as a solvent, but the system in step 1 was in a powder state.

[0094] Example 12 Silica fine particles were prepared using hollow silica (average particle size 1,900 nm, specific surface area 11.0 m ２ Hollow silica having polystyrene graft chains was obtained in the same manner as in Example 1, except that the amount of butyl methacrylate was changed to styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), the amount of silane coupling agent was changed to the amounts shown in Table 3, and the amount of catalyst was changed to the amounts shown in Table 3. In this example, no solvent was used, so the system was in a powder state in step 1.

[0095] The hollow silica used in Example 12 was produced as follows. 388.6 g of ion-exchanged water, 200 g of dodecane (Kishida Chemical Co., Ltd.: primary n-dodecane), and 11.4 g of QUARTAMINE 86W (Kao Corporation: containing 28% by mass of stearyl trimethyl ammonium chloride) were mixed and stirred to obtain Emulsion A. 13,192.5 g of ion-exchanged water, 138.1 g of Emulsion A, 125.6 g of QUARTAMINE 24P (Kao Corporation: containing 27.5% by mass of lauryl trimethyl ammonium chloride), and 3,120.8 g of ethyl orthosilicate (Wacker Asahi Kasei Silicones: TEOS999) were placed in a reaction vessel and heated to 40°C with stirring, followed by stirring 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 Kotamine 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 liquid D. The obtained cloudy liquid D was then filtered using 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 obtained hollow silica particle precursor was calcined at 1100°C for 1 hour to obtain hollow silica.

[0096] The raw materials used and the results of each of the above examples are summarized in the table below. Note that the particles immediately after step 1 in Examples 1 to 12 all passed through a funnel (with a lower outlet diameter of 5 mm) without resistance.

[0097]

[0098]

[0099]

[0100] *The amount (parts by mass) of the silane coupling agent used relative to 100 parts by mass of inorganic particles. **The angle of repose of the particles immediately after the end of step 1. ***The graft density (chains / nm) of the polymer graft chains on the surface of the obtained composite particles. ２The solvents ethanol, dichloromethane, and water, the silane coupling agents APTMS-Br, PTMS-Br, and Ts-Cl, and the catalyst triethylamine were all liquid components at 1 atmosphere.

[0101] In Comparative Example 1, composite particles were produced using the same inorganic particles as in Example 4, except that a silane compound having a chlorosulfonyl group was used as the polymerization initiator group. The graft density of the polymer graft chains on the surface of the obtained composite particles was 0.01 chains / nm. ２ On the other hand, the graft density of the polymer graft chains on the surface of the inorganic composite particles produced in Example 4 was 0.18 chains / nm ２ This result suggests that when a silane compound having a halosulfonyl group is used as a polymerization initiator group, the graft density of the polymer graft chains on the surface of the obtained inorganic composite particles decreases. The reason for this is presumably that the halosulfonyl group tends to generate radicals more frequently, causing the polymerization reaction to proceed too quickly, resulting in a decrease in graft density.

[0102] Comparing Example 1 and Example 2, it was found that the graft density of polymer graft chains on the surface of the obtained composite particles was higher in Example 2. This is thought to be because the presence of a good solvent for the silane coupling agent, such as ethanol, in Step 1 improved the dispersibility of the silane coupling agent.

[0103] Comparing Example 3 and Example 7, it was found that Example 7, which contained a smaller amount of silane coupling agent, had a higher graft density of polymer graft chains on the surface of the obtained composite particles. This is thought to be because the presence of water in addition to ethanol in Step 1 improved the reactivity of the silane coupling agent.

[0104] Reference Example 1 is an example in which the medium ethanol was used in an amount exceeding the predetermined amount during the synthesis of inorganic particles having polymerization initiator groups bonded thereto. Comparing Reference Example 1 with Examples 1 and 2, which used the same type of silica fine particles, it was found that the graft density of the polymer graft chains on the surface of the produced inorganic composite particles was lower in Reference Example 1 than in Example 1, which did not use a medium, or Example 2, which used a medium in an amount within the specified range.

[0105] Furthermore, Examples 10 and 11 show that composite particles having polymer graft chains can be produced even when a monomer other than butyl methacrylate, such as styrene, is used.

[0106] The composite particles obtained by the production method of the present invention can be used as a filler for a resin composition.

Claims

1. A method for producing composite particles having polymer graft chains, comprising the following steps, in which step 1 is carried out in a powder state. (Step 1) A step of reacting inorganic particles with a silane compound having a polymerization initiating group other than a halosulfonyl group to bond the polymerization initiating group to the inorganic particles; and (Step 2) A step of graft polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiating group is bonded.

2. Among the components used in step 1, the ratio of the total mass (B [g]) of liquid substances at 25°C and 1 atmosphere to the total surface area (A [m ２ ]) ratio ((A) / (B) [m ２ 2. The method according to claim 1, wherein the molecular weight of the polymer is 20 or more.

3. The method according to claim 1 or 2, wherein the ratio ((A') / (B)) of the total mass of inorganic particles (A' [g]) to the total mass of substances that are liquid at 25°C and 1 atmospheric pressure (B [g]) among the components used in step 1 is 2 or more.

4. The method according to any one of claims 1 to 3, comprising a step of contacting inorganic particles having polymerization initiation groups bonded thereto with a monomer under living radical polymerization conditions.

5. The graft density of the polymer chains on the surface of the composite particle is 0.001 chains / nm ２ More than 5 chains / nm ２ The method according to any one of claims 1 to 4, wherein:

6. The method according to any one of claims 1 to 5, wherein the amount of the silane compound having a polymerization initiating group other than a halosulfonyl group used is 0.1 parts by mass or more and 100 parts by mass or less per 100 parts by mass of inorganic particles.

7. The method according to any one of claims 1 to 6, wherein the polymerization initiating group is an α-haloacyl group, a haloalkyl group, or a haloalkylphenyl group.

8. The method according to any one of claims 1 to 7, wherein in step 1, one or more selected from the group consisting of ethanol, dichloromethane, toluene, acetone, tetrahydrofuran, methanol, butanol and butyl cellosolve are further used.

9. The method according to any one of claims 1 to 8, further comprising using a catalyst in step 1.

10. A method for producing a resin composition, comprising the step of mixing the composite particles obtained by the method according to any one of claims 1 to 9 with a resin.

11. A method for producing composite particles having polymer graft chains, comprising the following steps: Composite particles obtained by the method for producing composite particles, in which step 1 is carried out in a powder state; and a resin composition comprising: (Step 1) a step of reacting inorganic particles with a silane compound having a polymerization initiating group other than a halosulfonyl group to bond the polymerization initiating group to the inorganic particles; and (Step 2) a step of graft polymerizing a monomer in the presence of the inorganic particles to which the polymerization initiating group is bonded.

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