JP2024008588A - Polymer-coated low dielectric constant loss tangent silica sol and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silica particle with a dielectric loss tangent of 0.02 or less at 1 GHz and a method for producing the same.

SOLUTION: The present invention provides a surface-modified silica particle wherein a silylated polymer coats at least part of the particle surface or binds to at least part of the particle surface. The silica particle has an average primary particle size of 5-1000 nm and a dielectric loss tangent of 0.02 or less at 1 GHz. There is also provided a method for producing the same.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to silica particles with a low dielectric loss tangent (tan δ) and a method for producing the same.

In recent years, with the increase in the amount of information communication in the communication field such as 5G, the use of high frequency bands is expanding in electronic equipment, communication equipment, etc.
With the application of high frequency bands, the problem of increased transmission loss of circuit signals arises, so materials with low dielectric loss tangents are generally used for the insulators that make up electrical and electronic components such as antennas, circuits, and boards. . Polymer materials used as insulator materials generally have a low dielectric constant, but many have a high dielectric loss tangent. On the other hand, many ceramic materials have the opposite characteristics. Therefore, ceramic filler-filled polymer materials that combine these materials and have both low dielectric constant and low dielectric loss tangent properties have become popular. For example, Patent Document 1 proposes a composition in which an inorganic substance (inorganic magnesium fine particles) is blended into a thermoplastic resin and/or a thermosetting resin, aiming at a dielectric resin composition with a low dielectric constant and low dielectric loss. has been done.

As an example of a ceramic filler (inorganic filler), fused silica having a micro-order size is generally widely used (Patent Document 2). However, a problem with fused silica is that coarse particles produced during manufacturing have a significant impact on the performance of molded products. On the other hand, silica particles with an average particle size on the order of nanometers are less likely to produce coarse particles during manufacturing, and can be filtered or centrifuged, so even if coarse particles occur, they can be easily separated and removed. It is considered to be advantageous in that it is easy to use. Furthermore, nano-order particles are said to have various advantages, such as being able to be applied to transparent polymer materials and having a greater composite effect than micro-order fillers (Patent Document 3).

Japanese Patent Application Publication No. 2014-24916 Patent No. 6793282 Patent No. 6813815

Although nano-order particles have various advantages in the ceramic filler described above, existing nano-order particles have a high dielectric loss tangent, making it difficult to apply them to materials such as electronic devices that operate in high frequency bands.

The present invention was made in view of the above circumstances, and it is an object of the present invention to provide nano-order particles having a low dielectric loss tangent, specifically, silica particles having a dielectric loss tangent of 0.02 or less at 1 GHz, and the production thereof. The purpose is to provide a method.

As a result of repeated studies in good faith to solve the above problems, the present inventors found that the silica particles have an average primary particle diameter of 5 nm to 1000 nm and that at least a portion of the silica particle surface is modified with silylated particles (surface-modified silica particles). The present invention was completed based on the discovery that the particles (particles) exhibit low dielectric properties with a dielectric loss tangent (tan δ) of 0.02 or less at 1 GHz.

（式中、
Ｘは結合手を示し、
Ｒ^１は水素原子又はメチル基を示し、
Ｒ^２は水素原子の置換基であり、アルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はこれらの組み合わせであり、
ａは０～５の整数を示し、
Ｒ^３はアルコキシ基、アシルオキシ基、又はハロゲン基を示し、
Ｒ^４はアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はこれらの組み合わせであり、
Ａ^１は炭素原子数１～１０の炭化水素基を示し、
ｂは１～３の整数を示し、ｃは３－ｂを示し、
ｄは１～４の整数を示す。）
第３観点として、前記シリル化高分子が、式（３）で表される構造単位を含むシリル化高分子である、第１観点に記載の表面修飾シリカ粒子に関する。

（式中、
Ｒ^１は水素原子又はメチル基を示し、
Ｒ^２は水素原子の置換基であり、それぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^４はそれぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^３はアルコキシ基、アシルオキシ基、又はハロゲン基を示し、
Ａ^２は炭素原子数１～１０の炭化水素基を示し、
ａは０～５の整数を示し、ｂは１～３の整数を示し、ｃは３－ｂを示す。）
第４観点として、前記シリル化高分子が、式（４）で表される構造単位を含むシリル化高分子である、第１観点に記載の表面修飾シリカ粒子に関する。

（式中、
Ｒ^１は水素原子又はメチル基を示し、
Ｒ^２は水素原子の置換基であり、それぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^４はそれぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^３はアルコキシ基、アシルオキシ基、又はハロゲン基を示し、
ａは０～５の整数を示し、
ｂは１～３の整数を示し、ｃは３－ｂを示す。）
第５観点として、前記シリル化高分子が、５００～１０００００の数平均分子量を有する、第１観点乃至第４観点のいずれか１項に記載の表面修飾シリカ粒子に関する。
第６観点として、前記シリル化高分子が、分子量分布（Ｍｗ／Ｍｎ）＝１～２を有する、第５観点に記載の表面修飾シリカ粒子に関する。
第７観点として、前記シリル化高分子が、共有結合により前記シリカ粒子の少なくとも一部の表面に結合している、第１観点乃至第６観点のいずれか１項に記載の表面修飾シリカ粒子に関する。
第８観点として、前記シリル化高分子が、前記シリカ粒子の表面積１平方ｎｍ当たり、０．１～１．５個／ｎｍ^２の割合で結合している、第７観点に記載の表面修飾シリカ粒子に関する。
第９観点として、下記（ｉ）又は（ｉｉ）を満たし且つ加水分解性官能基を有するシリル化高分子からなる表面修飾剤で被覆された、第１観点乃至第８観点のいずれか一項に記載の表面修飾シリカ粒子に関する。
（ｉ）前記表面修飾剤の双極子間力が０．０１～２．０（ＭＰａ）^１／２である。
（ｉｉ）前記表面修飾剤の加水分解性官能基の当量、又は前記加水分解性官能基に由来するヒドロキシ基の当量が１５０～４０００（ｇ／ｅｑ）である
第１０観点として、第１観点乃至第９観点のいずれか１項に記載の表面修飾シリカ粒子が、水、アルコール類、ケトン類、炭化水素類、アミド類、エステル類、エーテル類又はアミン類から選ばれる少なくとも１種の溶媒に分散した、シリカゾルに関する。
第１１観点として、下記（Ａ）工程～（Ｃ）工程：
（Ａ）工程：平均一次粒子径５～１０００ｎｍを有するシリカ粒子を分散質とし炭素原子数１～４のアルコールを分散媒とするシリカゾルを準備する工程。
（Ｂ）工程：アルコール類、ケトン類、炭化水素類、アミド類、エステル類、エーテル類又はアミン類から選ばれる少なくとも１種の溶媒に溶解した前記式（３）又は式（４）で表されるシリル化高分子と、（Ａ）工程のシリカゾルを４０～８０℃で０．１～１０時間の加熱撹拌を行う工程、
（Ｃ）工程：（Ｂ）工程後のシリカゾルから前記溶媒を除去する工程、
を含む、
第３観点又は第４観点に記載のシリカ粒子の製造方法に関する。
第１２観点として、（Ｂ）工程及び（Ｃ）工程のいずれか一方又は両方が減圧下で行われる、第１１観点に記載のシリカ粒子の製造方法に関する。
第１３観点として、（Ａ）工程で準備するシリカゾルが、水分を０．０１～１０質量％含有するものである、第１１観点に記載のシリカ粒子の製造方法に関する。
第１４観点として、（Ａ）工程で準備するシリカゾルが、２００～３８０℃、２ＭＰａ～２２ＭＰａで水熱合成された水性シリカゾルを炭素原子数１～４のアルコールに溶媒置換したシリカゾルである、第１１観点に記載のシリカ粒子の製造方法に関する。
第１５観点として、第１観点乃至第９観点のいずれか１項に記載の表面修飾シリカ粒子と、有機樹脂が組み合わされた複合材料に関する。
第１６観点として、前記有機樹脂が、スチレン樹脂、エポキシ樹脂、シアネート樹脂、ベンゾオキサジン、フェノール樹脂、アクリル樹脂、マレイミド樹脂、ウレタン樹脂、ポリイミド、ポリテトラフルオロエチレン、シクロオレフィンポリマー、不飽和ポリエステル、ビニルトリアジン、架橋性ポリフェニレンオキサイド及び硬化性ポリフェニレンエーテルからなる群から選択される少なくとも１種である、第１５観点に記載の複合材料に関する。
第１７観点として、半導体デバイス材料、銅張積層板、集積回路、フレキシブル配線材料、フレキシブルディスプレイ材料、アンテナ材料、光配線材料及びセンシング材料からなる群から選択される用途を有する、第１５観点又は第１６観点に記載の複合材料に関する。 That is, the present invention
As a first aspect, particles in which at least a part of the particle surface is coated with a silylated polymer or bonded to at least a part of the particle surface, and the average primary particle diameter is 5 to 1000 nm, The present invention relates to silica particles having a dielectric loss tangent of 0.02 or less at 1 GHz.
As a second aspect, the surface modification according to the first aspect, wherein the silylated polymer has a structural unit represented by formula (1) and a structural unit represented by formula (2). Regarding silica particles.

(In the formula,
X indicates a bond,
R ¹ represents a hydrogen atom or a methyl group,
^R2 is a substituent for a hydrogen atom, and is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, or an acryloyl group, a methacryloyl group, a mercapto group, or an amino group. , an organic group having an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
a represents an integer from 0 to 5,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
^R4 is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, an organic group having a cyano group, or a combination thereof,
A ¹ represents a hydrocarbon group having 1 to 10 carbon atoms,
b represents an integer from 1 to 3, c represents 3-b,
d represents an integer from 1 to 4. )
A third aspect relates to the surface-modified silica particles according to the first aspect, wherein the silylated polymer is a silylated polymer containing a structural unit represented by formula (3).

(In the formula,
R ¹ represents a hydrogen atom or a methyl group,
R ² is a substituent for a hydrogen atom, and each independently represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, or a mercapto group. , an organic group having an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
R ⁴ is each independently an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, or a hydroxy group. group, an alkoxy group, an ester group, a sulfonyl group, or an organic group having a cyano group, or a combination thereof,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
A ² represents a hydrocarbon group having 1 to 10 carbon atoms,
a represents an integer from 0 to 5, b represents an integer from 1 to 3, and c represents 3-b. )
A fourth aspect relates to the surface-modified silica particles according to the first aspect, wherein the silylated polymer is a silylated polymer containing a structural unit represented by formula (4).

(In the formula,
R ¹ represents a hydrogen atom or a methyl group,
R ² is a substituent for a hydrogen atom, and each independently represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, or a mercapto group. , an organic group having an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
R ⁴ is each independently an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, or a hydroxy group. group, an alkoxy group, an ester group, a sulfonyl group, or an organic group having a cyano group, or a combination thereof,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
a represents an integer from 0 to 5,
b represents an integer from 1 to 3, and c represents 3-b. )
A fifth aspect relates to the surface-modified silica particles according to any one of the first to fourth aspects, wherein the silylated polymer has a number average molecular weight of 500 to 100,000.
A sixth aspect relates to the surface-modified silica particles according to the fifth aspect, wherein the silylated polymer has a molecular weight distribution (Mw/Mn) of 1 to 2.
A seventh aspect relates to the surface-modified silica particles according to any one of the first to sixth aspects, wherein the silylated polymer is bonded to the surface of at least a portion of the silica particles through a covalent bond. .
As an eighth aspect, the surface-modified silica according to the seventh aspect, wherein the silylated polymer is bonded at a rate of 0.1 to 1.5 pieces/nm ² per square nm of surface area of the silica particle. Regarding particles.
As a ninth aspect, the surface modifying agent according to any one of the first to eighth aspects satisfies (i) or (ii) below and is coated with a surface modifier made of a silylated polymer having a hydrolyzable functional group. The present invention relates to the surface-modified silica particles described above.
(i) The dipole force of the surface modifier is 0.01 to 2.0 (MPa) ^1/2 .
(ii) The equivalent weight of the hydrolyzable functional group of the surface modifier or the equivalent weight of the hydroxy group derived from the hydrolyzable functional group is 150 to 4000 (g/eq). The surface-modified silica particles according to any one of the ninth aspects are dispersed in at least one solvent selected from water, alcohols, ketones, hydrocarbons, amides, esters, ethers, or amines. Regarding silica sol.
As the eleventh aspect, the following steps (A) to (C):
(A) Step: A step of preparing a silica sol using silica particles having an average primary particle diameter of 5 to 1000 nm as a dispersoid and an alcohol having 1 to 4 carbon atoms as a dispersion medium.
(B) Step: A compound represented by the above formula (3) or formula (4) dissolved in at least one solvent selected from alcohols, ketones, hydrocarbons, amides, esters, ethers, or amines. a step of heating and stirring the silylated polymer and the silica sol of step (A) at 40 to 80°C for 0.1 to 10 hours;
(C) step: a step of removing the solvent from the silica sol after step (B);
including,
The present invention relates to a method for producing silica particles according to the third or fourth aspect.
A twelfth aspect relates to the method for producing silica particles according to the eleventh aspect, wherein either or both of the step (B) and the step (C) are performed under reduced pressure.
A thirteenth aspect relates to the method for producing silica particles according to the eleventh aspect, wherein the silica sol prepared in step (A) contains 0.01 to 10% by mass of water.
As a fourteenth aspect, the silica sol prepared in step (A) is a silica sol obtained by solvent-substituting an aqueous silica sol hydrothermally synthesized at 200 to 380° C. and 2 MPa to 22 MPa with an alcohol having 1 to 4 carbon atoms. The present invention relates to a method for producing silica particles according to the aspect.
A fifteenth aspect relates to a composite material in which the surface-modified silica particles according to any one of the first to ninth aspects are combined with an organic resin.
As a 16th aspect, the organic resin is styrene resin, epoxy resin, cyanate resin, benzoxazine, phenol resin, acrylic resin, maleimide resin, urethane resin, polyimide, polytetrafluoroethylene, cycloolefin polymer, unsaturated polyester, vinyl The present invention relates to the composite material according to the fifteenth aspect, which is at least one member selected from the group consisting of triazine, crosslinkable polyphenylene oxide, and curable polyphenylene ether.
The 15th or 17th aspect has an application selected from the group consisting of semiconductor device materials, copper-clad laminates, integrated circuits, flexible wiring materials, flexible display materials, antenna materials, optical wiring materials, and sensing materials. The present invention relates to the composite material according to aspect 16.

The silica particles (surface-modified silica) of the present invention have the effect of exhibiting low dielectric properties. It can also be well dispersed in organic solvents. Furthermore, since the silica particles according to the present invention can be used to form composite materials with various organic resins, they can be expected to be used in the production of semiconductor device materials.
In addition, in one embodiment of the silica particles (surface-modified silica particles) of the present invention, since a polymer is bonded to the particle surface, it can be expected to impart high toughness unique to polymers, and exhibit better mechanical properties. It is expected to be used in the production of composite materials.

Figure 1 is a diagram showing a schematic diagram of the flow reactor (reaction device) used in Synthesis Examples 2-1 to 2-4. FIG. 2 is a diagram showing the results of MALDI-TOF-MS measurement of the polymer (surface modifier A) prepared in Synthesis Example 2-1. FIG. 3 is a diagram showing the results of ¹ H-NMR measurement of the polymer (surface modifier A) prepared in Synthesis Example 2-1. FIG. 5 is a diagram showing the results of MALDI-TOF-MS measurement of the polymer (surface modifier D) prepared in Synthesis Example 2-4. FIG. 5 is a diagram showing the results of ¹ H-NMR measurement of the polymer (surface modifier D) prepared in Synthesis Example 2-4.

<Surface modified silica particles>
The silica particles of the present invention are particles in which a silylated polymer coats at least a part of the particle surface or is bonded to at least a part of the particle surface, and has an average primary particle diameter of 5 to 1000 nm. It is a silica particle with a dielectric loss tangent of 0.02 or less at 1 GHz.

<Average primary particle diameter>
As the average primary particle diameter of the silica particles according to the present invention, the specific surface area diameter calculated from the specific surface area (S _N2 ) measured by the BET method using nitrogen gas as molecules adsorbed on the particle surface can be adopted. .
The specific surface area diameter (average primary particle diameter: D (nm)) is determined by the formula D (nm) = 2720/S _N2 from the specific surface area S _N2 (m ² /g) measured by the nitrogen adsorption method (BET method). It is the primary particle diameter calculated by , and means the particle diameter converted to spherical silica particles.
The silica particles according to the present invention may have an average primary particle diameter in the range of 5 nm to 1000 nm, for example in the range of 5 nm to 500 nm, or for example in the range of 10 nm to 150 nm.
Silica particles having an average primary particle diameter of 5 nm to 1000 nm exhibit a low dielectric loss tangent and can be well dispersed in an organic solvent. Moreover, when a composite material using the silica particles is molded, defects can be suppressed and high transparency can be exhibited.

The silica particles of the present invention have an embodiment in which at least a part of the surface of the silica particles is coated with silylated particles described below, or at least a part of the silylated particles are bonded to the surface of at least a part of the silica particles. In other words, the surface-modified silica particles have a surface modified with silylated particles. Hereinafter, these aspects will be collectively referred to as the silica particles of the present invention as "surface-modified silica particles."
As used herein, "surface modification" includes both an embodiment in which the silica particle surface is coated with the silylated particles and an embodiment in which the silylated particles are bonded to the silica particle surface.
In the present invention, "at least a portion of the surface of the silica particle is coated with silylated particles" may be an embodiment in which at least a portion of the surface of the silica particle is coated with the silylated particles described below, i.e. , an embodiment in which the silylated particles cover a part of the surface of the silica particle, and an embodiment in which the silylated particle covers the entire surface of the silica particle. In this embodiment, it does not matter whether or not there is a bond between the organosilicon compound and the surface of the silica particle.
In addition, in the present invention, "at least a part of the silylated particles are bonded to at least a part of the surface of the silica particle" refers to an embodiment in which the silylated particles described below are bonded to at least a part of the surface of the silica particle. In other words, an embodiment in which the silylated particles are bonded to a part of the surface of the silica particle, an embodiment in which the silylated particles are bonded to a part of the surface of the silica particle and cover at least a part of the surface, and This includes embodiments in which the silylated particles bond to and cover the entire surface of the silica particles.

One of the preferred embodiments of the silica particles of the present invention is an embodiment in which a silylated polymer is bonded to at least a portion of the surface of the silica particles through covalent bonds.
Another embodiment is one coated with a silylated polymer.

Note that there are no particular restrictions on the manufacturing method for unmodified silica particles (particles that are not coated or bonded with silylated polymers) constituting the silica particles of the present invention, but preferably in water at 200 to 380°C. It has been heat treated (hydrothermal treatment). The heat treatment can be performed using a pressure-resistant container (autoclave), and can be performed under, for example, 2 MPa to 22 MPa.

<Silylated polymer>
The silylated polymer corresponds to a surface modifier for (unmodified) silica particles, and is preferably a silylated polymer having a hydrolyzable functional group or the like.
In the present invention, the silylated polymer refers to a polymer in which a group derived from an organosilicon compound having a hydrolyzable functional group is bonded to any part of the polymer chain.
The bonding site of the group derived from the silane compound having the hydrolyzable functional group in the polymer chain is not particularly limited, and may be, for example, at the end of the polymer chain, a side chain of the polymer chain, or the like.
Further, the hydrolyzable functional group is preferably an alkoxy group, an acyloxy group, or a halogen atom, and when a plurality of them exist, they may be the same or different from each other.
Further, as the polymer (polymer chain), polymerizable monomers such as vinyl monomers such as ethylene, styrene, vinyl chloride, butadiene, acrylic esters, methacrylic esters, acrylonitrile, and vinyl acetate may be polymerized alone or copolymerized. Examples include (co)polymers formed by:

The silylated polymer may have a number average molecular weight of, for example, 500 to 100,000, or, for example, 1,000 to 50,000.
Further, the silylated polymer may have a molecular weight distribution (weight average molecular weight: Mw/number average molecular weight: Mn) of 1 to 2, for example.
Note that the number average molecular weight and weight average molecular weight are molecular weights obtained in terms of polystyrene by gel permeation chromatography (GPC) analysis.

上記式中、
Ｘは結合手を示し、
Ｒ^１は水素原子又はメチル基を示し、
Ｒ^２は水素原子の置換基であり、アルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はこれらの組み合わせであり、
ａは０～５の整数を示し、
Ｒ^３はアルコキシ基、アシルオキシ基、又はハロゲン基を示し、
Ｒ^４はアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はこれらの組み合わせであり、
Ａ^１は炭素原子数１～１０の炭化水素基を示し、
ｂは１～３の整数を示し、ｃは３－ｂを示し、
ｄは１～４の整数を示す。 Specific, non-limiting examples of the silylated polymer include those having a structural unit represented by the following formula (1) and a structural unit represented by the formula (2).

In the above formula,
X indicates a bond,
R ¹ represents a hydrogen atom or a methyl group,
^R2 is a substituent for a hydrogen atom, and is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, or an acryloyl group, a methacryloyl group, a mercapto group, or an amino group. , an organic group having an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
a represents an integer from 0 to 5,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
^R4 is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, an organic group having a cyano group, or a combination thereof,
A ¹ represents a hydrocarbon group having 1 to 10 carbon atoms,
b represents an integer from 1 to 3, c represents 3-b,
d represents an integer from 1 to 4.

上記式（３）中、
Ｒ^１は水素原子又はメチル基を示し、
Ｒ^２は水素原子の置換基であり、それぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^４はそれぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^３はアルコキシ基、アシルオキシ基、又はハロゲン基を示し、
Ａ^２は炭素原子数１～１０の炭化水素基を示し、
ａは０～５の整数を示し、ｂは１～３の整数を示し、ｃは３－ｂを示す。） Furthermore, as a non-limiting specific example of the silylated polymer, a silylated polymer containing a structural unit represented by the following formula (3) can be mentioned.

In the above formula (3),
R ¹ represents a hydrogen atom or a methyl group,
R ² is a substituent for a hydrogen atom, and each independently represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, or a mercapto group. , an organic group having an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
R ⁴ is each independently an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, or a hydroxy group. group, an alkoxy group, an ester group, a sulfonyl group, or an organic group having a cyano group, or a combination thereof,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
A ² represents a hydrocarbon group having 1 to 10 carbon atoms,
a represents an integer from 0 to 5, b represents an integer from 1 to 3, and c represents 3-b. )

上記式（４）中、
Ｒ^１は水素原子又はメチル基を示し、
Ｒ^２は水素原子の置換基であり、それぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^４はそれぞれ独立にアルキル基、アリール基、ハロゲン化アルキル基、ハロゲン化アリール基、アルコキシアリール基、アルケニル基、アシルオキシアルキル基、又はアクリロイル基、メタクリロイル基、メルカプト基、アミノ基、アミド基、ヒドロキシ基、アルコキシ基、エステル基、スルホニル基、もしくはシアノ基を有する有機基、又はそれらの組み合わせであり、
Ｒ^３はアルコキシ基、アシルオキシ基、又はハロゲン基を示し、
ａは０～５の整数を示し、
ｂは１～３の整数を示し、ｃは３－ｂを示す。 Further, as a non-limiting specific example of the silylated polymer, a silylated polymer containing a structural unit represented by the following formula (4) can be mentioned.

In the above formula (4),
R ¹ represents a hydrogen atom or a methyl group,
R ² is a substituent for a hydrogen atom, and each independently represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, or a mercapto group. , an organic group having an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
R ⁴ is each independently an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, or a hydroxy group. group, an alkoxy group, an ester group, a sulfonyl group, or an organic group having a cyano group, or a combination thereof,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
a represents an integer from 0 to 5,
b represents an integer from 1 to 3, and c represents 3-b.

The alkyl group in R ² and R ⁴ in the above formula is, for example, a linear or branched alkyl group having 1 to 10 carbon atoms, such as a methyl group, ethyl group, n-propyl group, i -Propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl -n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl-n-propyl group, n- Hexyl, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1 , 2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n -butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1- Examples include, but are not limited to, ethyl-1-methyl-n-propyl group and 1-ethyl-2-methyl-n-propyl group.
Examples of the aryl group include aryl groups having 6 to 40 carbon atoms, such as phenyl group, o-methylphenyl group, m-methylphenyl group, p-methylphenyl group, o-chlorophenyl group, m- Chlorphenyl group, p-chlorophenyl group, o-fluorophenyl group, p-mercaptophenyl group, o-methoxyphenyl group, p-methoxyphenyl group, p-aminophenyl group, p-cyanophenyl group, α-naphthyl group , β-naphthyl group, o-biphenylyl group, m-biphenylyl group, p-biphenylyl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group , 4-phenanthryl group, and 9-phenanthryl group, but are not limited thereto.
The halogenated alkyl group and the halogenated aryl group mean a monovalent group in which one hydrogen atom of the alkyl group or aryl group is replaced with a halogen. Examples of the halogen include fluorine atom, chlorine atom, bromine atom, and iodine atom.
The alkoxyaryl group means a monovalent group in which one hydrogen atom of the annealing group is replaced with an alkoxy group described below.
The alkenyl group is, for example, an alkenyl group having 2 to 10 carbon atoms, such as ethenyl group, 1-propenyl group, 2-propenyl group, 1-methyl-1-ethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group, 1-methyl-2-propenyl group, 1-pentenyl group , 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-n-propylethenyl group, 1-methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl -2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2- Examples include, but are not limited to, dimethyl-2-propenyl group.
The acyloxyalkyl group is an acyloxy group in which one hydrogen atom of the alkyl group is an acyloxy group, such as a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, an i-propylcarbonyloxy group, an n-butylcarbonyloxy group, i-butylcarbonyloxy group, s-butylcarbonyloxy group, t-butylcarbonyloxy group, n-pentylcarbonyloxy group, 1-methyl-n-butylcarbonyloxy group, 2-methyl-n-butylcarbonyloxy group, It means a monovalent group substituted for an acyloxy group such as 3-methyl-n-butylcarbonyloxy group.

Examples of the organic group having an acryloyl group include an acryloylmethyl group, an acryloylethyl group, an acryloylpropyl group, and the like.
Examples of the organic group having a methacryloyl group include a methacryloylmethyl group, a methacryloyl ethyl group, a methacryloylpropyl group, and the like.
Examples of the organic group having a mercapto group include an ethylmercapto group, a butylmercapto group, a hexylmercapto group, an octylmercapto group, a mercaptophenyl group, and the like.
Examples of the organic group containing an amino group include, but are not limited to, an amino group, an aminomethyl group, an aminoethyl group, an aminophenyl group, a dimethylaminoethyl group, a dimethylaminopropyl group, and the like.
Examples of the organic group containing an amide group include, but are not limited to, an amide group and an amide methyl group.
Examples of the organic group containing a hydroxy group include, but are not limited to, a hydroxy group, a hydroxymethyl group, a hydroxyethyl group, a hydroxyphenyl group, and the like.
Examples of the organic group containing the alkoxy group include, but are not limited to, a methoxymethyl group and a methoxyethyl group. However, groups in which an alkoxy group is directly bonded to a silicon atom (corresponding to ^R3 ) are excluded.
Examples of the organic group containing an ester group (ester bond) include an acetoxymethyl group and an acetoxyethyl group.
Examples of the organic group containing the sulfonyl group include, but are not limited to, a sulfonylalkyl group and a sulfonylaryl group.
Examples of the organic group having a cyano group include a cyanoethyl group, a cyanopropyl group, a cyanophenyl group, and a thiocyanate group.

Examples of the alkoxy group and acyloxy group in R ³ in the above formula include the groups listed as the alkoxy group and acyloxy group in R ² and R ⁴ .
Examples of the halogen group include a fluoro group, a chloro group, a bromo group, and an iodo group.
Note that R ³ is a group corresponding to the above-mentioned hydrolyzable functional group.

The hydrocarbon group having 1 to 10 carbon atoms in A ¹ in the above formula includes the aforementioned alkyl group, aryl group, halogenated alkyl group, halogenated aryl group, alkoxyaryl group, alkenyl group, and acyloxyalkyl group. Among the groups, the upper limit of the number of carbon atoms is 10, and examples include monovalent to tetravalent groups in which 0 to 3 hydrogen atoms are removed from any carbon atom such as the above-mentioned alkyl group.
Further, as the hydrocarbon group having 1 to 10 carbon atoms in ^A2 , the groups mentioned above as the alkyl group, aryl group, halogenated alkyl group, halogenated aryl group, alkoxyaryl group, alkenyl group, and acyloxyalkyl group are used. Examples include divalent to tetravalent groups in which the upper limit of the number of carbon atoms is 10 and 13 hydrogen atoms are removed from any carbon atom such as the alkyl group described above.

The silylated polymer according to the present invention is produced by adding and reacting with an organosilicon compound having a hydrolyzable functional group during the (co)polymerization of a polymerizable monomer such as styrene as described above. The silylated polymer can be obtained by introducing a group derived from an organosilicon compound having a group. When the organosilicon compound is introduced at the end of a polymer chain or into a polymer chain, it can function as a polymerization terminator or constitute one block of a block copolymer.
Note that, for example, using the flow reactor (reactor) shown in FIG. 1 used in the Examples described later, synthesis of the polymer chain and introduction of the organosilicon compound are continuously performed to obtain the desired silylated polymer. be able to.
The (co)polymerization reaction (synthesis of polymer chains) of polymerizable monomers is carried out in the presence of a polymerization initiator such as an organolithium compound, and considering the subsequent introduction of an organosilicon compound, the polymerization initiator: the hydrolyzable The organosilicon compound having a functional group can be used in a ratio of 1:1 to 100 (mole ratio), for example, the amount of the organosilicon compound 5 times that of the initiator.

The organosilicon compound having a hydrolyzable functional group has, in addition to the hydrolyzable functional group, a group capable of reacting (bonding) with the growth species generated during polymerization, and the group includes a halogen group (chloro group, etc.). ), vinyl groups (including (meth)acrylic groups, etc.), and the like.
Examples of such organosilicon compounds include, but are not limited to, halogen groups such as triethoxyfluorosilane, 3-chloropropyltrimethoxysilane, 3-bromopropyltriethoxysilane, and 2-chloroethylmethyldimethoxysilane. and organosilicon compounds having an alkoxy group as a hydrolyzable functional group; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinylmethyldiethoxysilane, divinyldimethoxysilane, divinyldiethoxysilane, divinyldipropoxysilane, etc. Organosilicon compounds having a vinyl group and an alkoxy group as a hydrolyzable functional group; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyl Examples include organosilicon compounds having a (meth)acrylic group such as methyldimethylsilane and an alkoxy group as a hydrolyzable functional group.
Further, for example, the organosilicon compound having the above-mentioned hydrolyzable functional group includes a compound having an isocyanate group, an epoxy group, an acid anhydride group, an acid halide group, etc. in addition to the above-mentioned hydrolyzable functional group. Specific non-limiting examples of these include 3-isocyanatepropyltriethoxysilane, 2-isocyanateethyltri-n-propoxysilane, 3-isocyanatepropylmethyldimethoxysilane, 2-isocyanateethylethyldibutoxysilane, 3-isocyanatepropyldimethyliso Isocyanate groups such as propoxysilane, 2-isocyanateethyldiethylbutoxysilane, di(3-isocyanatepropyl)diethoxysilane, di(3-isocyanatepropyl)methylethoxysilane, ethoxysilane triisocyanate and alkoxy groups as hydrolyzable functional groups Organosilicon compounds having: 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane , organosilicon compounds having an epoxy group and an alkoxy group as a hydrolyzable functional group such as 3,4-epoxybutyltrimethoxysilane; acid anhydrides such as 3-(triethoxysilyl)-2-methylpropylsuccinic anhydride an organosilicon compound having an alkoxy group as a hydrolyzable functional group; an organosilicon compound having an acid halide group such as 2-(4-chlorosulfonylphenyl)ethyltriethoxysilane and an alkoxy group as a hydrolyzable functional group; etc. can be mentioned.

As the silylated polymer, a silylated polymer having a hydrolyzable functional group that satisfies (i) or (ii) below can be employed. In other words, the silica particles according to the present invention have their surfaces modified (bonded/coated) with a surface modifier made of a silylated polymer that satisfies the following (i) or (ii) and has a hydrolyzable functional group. can be taken as a thing.
(i) The dipole force of the surface modifier (silylated polymer) is 0.01 to 2.0 (MPa) ^1/2 .
(ii) The equivalent weight of the hydrolyzable functional group of the surface modifier (silylated polymer) or the equivalent weight of the hydroxyl group derived from the hydrolyzable functional group is 150 to 4000 (g/eq).

The dipole-dipole force is one of the forces generated by electrostatic interaction between molecules, and is a force that acts between two molecules that form a permanent dipole.
The smaller the dipole-dipole force, the lower the dielectric constant, and the lower the dielectric loss tangent. Therefore, in the present invention, the dipole force of the surface modifier (silylated polymer) is preferably in the range of 0.01 to 2.0 (MPa) ^1/2 , thereby achieving low dielectric properties (at 1 GHz). This is aimed at achieving a dielectric loss tangent (tan δ) of 0.02 or less.
In the present invention, solubility parameter calculation software (Hansen SP&QSPR model, Winmostar V10, X-Ability Co. Ltd., Japan-Tokyo, 2020) is used based on the molecular weight and molecular structure information of the silylated polymer, which is a surface modifier. The calculated value is adopted as the dipole force of the surface modifier (silylated polymer).
In the present invention, the dipole force of the surface modifying agent (silylated polymer) is 0.01 to 2.0 (MPa) ^1/2 , so that the dielectric property (dielectric loss tangent (tan δ) at 1 GHz) is 0. .02 or less).

In addition, in order to achieve low dielectric properties, it is important to eliminate the presence of water in _the system as much as possible. It is desirable to control the amount of hydrolyzable functional groups produced.
Therefore, in the present invention, the equivalent weight of the hydrolyzable functional group in the silylated polymer that is the surface modifier, and the equivalent weight of the hydroxyl group derived from the hydrolyzable functional group, is set to, for example, 50 to 4000 (g/eq). By setting it in the range of , low dielectric characteristics (dielectric loss tangent (tan δ) at 1 GHz of 0.02 or less) are achieved.

<Surface modification>
The amount of surface treatment (modification) with the silylated polymer, that is, the amount (number) of silylated polymers coated on or bonded to the silica particle surface is, for example, 0.1 per 1 nm ² of surface area of the silica particle. It can be in the range of about 1.5 to 1.5 pieces.

The method for producing surface-modified silica particles, that is, the method for coating (surface treatment) the surface of silica particles with the silylated polymer, is not particularly limited. By adding and mixing at least one type of silylated polymer, hydrolysis and condensation of the hydrolyzable functional groups of the silylated polymer occur, thereby modifying the surface of the (unmodified) silica particles.

The amount of the silylated polymer to be added can be such that, for example, about 0.1 to 1.5 silylated polymers are added to the surface per 1 nm ² of the surface area of the silica particles. For example, 0.1 to ^1.5 particles, or 0.1 to 1.0 particles, or 0.5 to 1.0 particles, or 0.1 to 0.5 particles per 1 nm2 of surface area of silica particles. A silylated polymer can be added so that the surface is modified at a ratio such that: Although surplus silylated polymers that do not contribute to surface modification may be present in the system, the preferred amount of silylated polymers added is 0.1 to 1.5 silica particles per ¹ nm2 of surface area. .

Hydrolysis of the silylated polymer can be carried out either completely or partially, but water is required and per mole of the hydrolyzable functional group of the silylated polymer. It is preferable to add about 1 mol or more of water. Furthermore, water contained in the organic solvent can also be used.
When using a silylated polymer having a hydrolyzable functional group, hydrolysis may be carried out either completely or partially, but water is required and the silylated polymer may be hydrolyzed completely or partially. It is preferable to add about 1 mol or more of water per 1 mol of the hydrolyzable functional group. Furthermore, water contained in the organic solvent can also be used.
A catalyst can also be used during hydrolysis and condensation. As the hydrolysis catalyst, a chelate compound, an organic acid, an inorganic acid, an organic base, or an inorganic base can be used alone or in combination. More specifically, for example, an aqueous solution of hydrochloric acid, acetic acid, an aqueous ammonia solution, etc. can be used.

<Method for producing silica particles>
An example of the method for producing silica particles (surface-modified silica particles) of the present invention is shown below.
The silica particles of the present invention can be produced, for example, by including the following steps (A) to (C), but are not limited to these production methods (steps).
(A) Step: preparing a silica sol using silica particles having an average primary particle diameter of 5 to 1000 nm as a dispersoid and an alcohol having 1 to 4 carbon atoms as a dispersion medium;
(B) Step: For example, the formula (3) or formula (4) is dissolved in at least one solvent selected from alcohols, ketones, hydrocarbons, amides, esters, ethers, or amines. A step of heating and stirring the represented silylated polymer and the silica sol of step (A) at 40 to 80°C for 0.1 to 10 hours,
(C) Step: A step of removing the solvent from the silica sol after the step (B).

<(A) Process>
Step (A) is a step of preparing silica sol.
That is, "silica particles having an average primary particle diameter of 5 to 1000 nm" in step (A) are silica particles whose particle surfaces are not modified with a silylated polymer (unmodified), that is, prepared in this step. Silica sol is unmodified silica sol.
As described above, as the unmodified silica sol, for example, a hydrothermally synthesized aqueous silica sol can be used.
In a preferred embodiment, the silica sol prepared in step (A) may be a silica sol obtained by substituting an aqueous silica sol hydrothermally synthesized at 200 to 380° C. and 2 MPa to 22 MPa with an alcohol having 1 to 4 carbon atoms. can. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, isopropyl alcohol, and n-butanol.
In a preferred embodiment, the silica sol prepared in step (A) can have a water content of 0.01 to 10% by mass.

<(B) Process>
Step (B) is a step of mixing silica particles and a silylated polymer, and surface-modifying the silica particles by hydrolysis and condensation of the silylated polymer.
The moisture, catalyst, etc. involved in hydrolysis are as described above.

In the step (B), the amount of the silylated polymer added is, for example, 0.1 to 1.5 particles per 1 nm ² of surface area of the silica particles contained in the silica sol in the step (A). It can be the amount. Specifically, 0.1 to 1.5 particles, or 0.1 to 1.0 particles, or 0.5 to 1.0 particles, or 0.1 to 1.5 particles per 1 nm ² of surface area of silica particles. A silylated polymer can be added so that the surface is modified at a ratio of 0.5. Note that an excess organosilicon compound that does not contribute to surface modification may be present in the reaction system.

The organic solvent used in the subsequent reaction to dissolve the silylated polymer in step (B) is at least one selected from alcohols, ketones, hydrocarbons, amides, esters, ethers, and amines. It is a solvent for
Examples of the alcohols include alcohols having 1 to 5 carbon atoms, and specific examples include methanol, ethanol, isopropyl alcohol, and n-butanol.
Examples of the ketones include ketones having 1 to 5 carbon atoms, and specifically, methyl ethyl ketone, methyl isobutyl ketone, γ-butyllactone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone. Examples include.
Examples of the hydrocarbons include toluene, xylene, n-pentane, n-hexane, and cyclohexane.
Examples of the amides include dimethylacetamide, N,N-dimethylformamide, dimethylacrylamide, acryloylmorpholine, diethylacrylamide, and the like.
Examples of the esters include ethyl acetate and butyl acetate.
Examples of the ethers include ethylene glycol monomethyl ether and propylene glycol monomethyl ether.
Examples of the amines include triethylamine, tributylamine, N,N-dimethylaniline, pyridine, and picoline.

The step (B) is not particularly limited as long as the temperature allows the hydrolysis and condensation reaction of the hydrolyzable functional group of the silylated polymer to proceed, for example, at a temperature of 20°C or higher and lower than 120°C, particularly 40 to 80°C. It can be carried out at a temperature of °C.
In terms of reaction efficiency, it is preferable to carry out the reaction near the boiling point of the organic solvent. For example, if the mixing step is carried out using an organic solvent containing methanol, it is preferable to carry out the reaction at a temperature of about 60 to 65°C. In addition, for the purpose of suppressing changes in the silica concentration and silylated polymer concentration in this step, the reaction may be carried out in an apparatus equipped with a reflux device or the like, if necessary. Further, this step can be performed multiple times at the same temperature or multiple times at different temperatures.
Note that this step is desirably carried out within 24 hours from an industrial point of view, and can be carried out, for example, in 0.1 to 10 hours.

Note that the step (B) can include a step of adjusting the pH using an organic amine. This pH adjustment step can be performed once before step (B), during step (B), after step (B), or multiple times.
As the organic amine, a secondary or tertiary amine can be used. As the secondary or tertiary amine, alkylamines, allylamines, aralkylamines, alicyclic amines, alkanolamines, cyclic amines, etc. can be used.
Specifically, diethylamine, triethylamine, diisopropylamine, tri-isopropylamine, di-n-propylamine, tri-n-propylamine, diisobutylamine, di-n-butylamine, tri-n-butylamine, dipentylamine, tri- Pentylamine, di-2-ethylhexylamine, di-n-octylamine, tri-n-octylamine, N-ethyldiisopropylamine, dicyclohexylamine, N,N-dimethylbutylamine, N,N-dimethylhexylamine, N, N-dimethyloctylamine, N,N-dimethylbenzylamine, piperidine, N-methylpiperidine, quinuclidine, triethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N, N-dibutylethanolamine, triisopropanolamine, imidazole, imidazole derivative, 1,8-diaza-bicyclo(5,4,0)undec-7-ene, 1,5-diaza-bicyclo(4,3,0)nona Examples include -5-ene 1,4-diaza-bicyclo(2,2,2)octane, diallylamine, and the like. These organic basic compounds may be used alone or in combination of two or more.
The amount of organic amine added can be 0.001 to 5% by mass, or 0.01 to 1% by mass based on the mass of the silica particles. Further, by adding an organic amine, the pH of the mixed solution can be adjusted to 4.0 to 11.0, preferably 7.5 to 9.5.

<(C) Process>
This step is a step of removing the solvent from the silica sol after step (B), and can be carried out using, for example, a vacuum dryer.

Note that the steps (B) and (C) can be carried out under normal pressure or reduced pressure, but either or both of the steps (B) and (C) can be carried out under reduced pressure. , for example, under reduced pressure of 600 to 400 Torr.

Further, the sol after the step (B), that is, the sol containing surface-modified silica particles, can be used as a surface-modified silica dispersion in the production of a composite material, which will be described later.
At this time, from the viewpoint of ease of manufacturing the composite material, at least a part of the organic solvent contained in the sol in step (B) is replaced with another organic solvent, and this is used as a surface-modified silica dispersion. It can also be used. As the other organic solvent, at least one or two or more selected from the alcohols, ketones, hydrocarbons, amides, esters, ethers, and amines used in step (B) can be used. There is no particular restriction on the solvent to be substituted, as long as it is different from the organic solvent contained in the silica sol after step (B), and can be selected from the viewpoint of solubility of the organic resin to be composited.
A known method can be used for the substitution, for example, an evaporation method using a rotary evaporator or the like, or an ultrafiltration method using an ultrafiltration membrane can be used to replace the organic solvent with another organic solvent.

<Measurement of dielectric properties>
The dielectric constant and dielectric loss tangent of the (surface-modified) silica particles according to the present invention can be measured using dry powder of silica particles using a dedicated device. Examples of the dedicated device include a vector network analyzer (trade name: FieldFox N6626A, manufactured by KEYSIGHT TECHNOLOGIES).
When composited with an organic resin and applied to insulator applications, the dielectric loss tangent of the silica particles at a frequency of 1 GHz is preferably 0.02 or less, for example less than 0.02, 0.01 or less, particularly 0.009 or less. Further, the lower limit value of the dielectric loss tangent is 0.00001, or 0.00005, or 0.0001, or 0.0005.

<Silica sol (silica dispersion)>
In the silica sol according to the present invention, the silica particles (surface-modified silica particles) are dissolved in at least one solvent selected from water, alcohols, ketones, hydrocarbons, amides, esters, ethers, or amines. This is an embodiment of a dispersed silica sol (also referred to as a silica dispersion).
Examples of the alcohols include alcohols having 1 to 5 carbon atoms, and specific examples include methanol, ethanol, isopropyl alcohol, and n-butanol.
Examples of the ketones include ketones having 1 to 5 carbon atoms, and specifically, methyl ethyl ketone, methyl isobutyl ketone, γ-butyllactone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone. Examples include.
Examples of the hydrocarbons include toluene, xylene, n-pentane, n-hexane, and cyclohexane.
Examples of the amides include dimethylacetamide, N,N-dimethylformamide, dimethylacrylamide, acryloylmorpholine, diethylacrylamide, and the like.
Examples of the esters include ethyl acetate and butyl acetate.
Examples of the ethers include ethylene glycol monomethyl ether and propylene glycol monomethyl ether.
Examples of the amines include triethylamine, tributylamine, N,N-dimethylaniline, pyridine, and picoline.

The content of surface-modified silica particles in the silica sol (silica dispersion) can be expressed as silica concentration. The silica concentration can be calculated by measuring the firing residue obtained after firing the silica sol (silica dispersion) at 1000°C. The silica concentration in the silica sol (silica dispersion) can be, for example, 1% by mass to 60% by mass, 10% by mass to 60% by mass, or 10% by mass to 40% by mass.
Further, the water content of the silica sol (silica dispersion) is preferably 5% by mass or less. Such a water content may improve the stability of the sol (dispersion) and make it easier to obtain a composite material with an organic resin.

<Composite material (composite material)>
The composite material according to the present invention is a composite material containing the (surface-modified) silica particles according to the present invention and an organic resin.
The organic resins include styrene resin, epoxy resin, cyanate resin, benzoxazine, phenol resin, acrylic resin, maleimide resin, urethane resin, polyimide, polytetrafluoroethylene, cycloolefin polymer, unsaturated polyester, vinyl triazine, and crosslinkable polyphenylene. It can be selected from at least one member selected from the group consisting of oxides and curable polyphenylene ethers.

The method for producing the composite material is not particularly limited, but for example, after mixing the dispersion of the (surface-modified) silica particles and a monomer or polymer solution constituting the organic resin to prepare a polymerizable composition, After removing excess solvent, a composite material can be obtained by curing with light or heat. Alternatively, a composite material can also be obtained by directly adding powder of (surface-modified) silica particles to an organic resin monomer or polymer solution to create a polymerizable composition, removing excess solvent, and curing with light or heat. be able to.
The mixing ratio of the (surface modified) silica particles and the organic resin monomer or polymer solution in the polymerizable composition is the mass ratio of the (surface modified) silica particles to the organic resin monomer or polymer. : organic resin monomer or polymer=1:100 to 0.1, for example, 1:20 to 0.1.

The polymerizable composition can be cured with light or heat by using a polymerization initiator. Examples of the photopolymerization initiator include a radical photopolymerization initiator or a cationic photopolymerization initiator, and examples of the thermal polymerization initiator include a thermal radical polymerization initiator or a thermal cationic polymerization initiator. Further, the polymerization initiator can be used in an amount of 0.01 parts by mass to 50 parts by mass based on 100 parts by mass of the polymerizable compound.
In addition, as optional components, conventional additives used in conventional polymerizable compositions (composite materials), such as catalysts and pigments for accelerating curing, radical scavengers (quenchers), leveling agents, viscosity modifiers, oxidizing agents, etc. Various additives used in the technical field, such as inhibitors, ultraviolet absorbers, stabilizers, plasticizers, and surfactants, can also be used in combination.

The composite material of the present invention can be used as a semiconductor device material, a copper-clad laminate, an integrated circuit, a flexible wiring material, a flexible display material, an antenna material, an optical wiring material, or a sensing material by selecting an appropriate organic resin depending on the intended use. It can be used as a material.

EXAMPLES Hereinafter, the present invention will be explained in more detail by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Silica sol]
The silica particles (silica sol) used in Examples and Comparative Examples are as follows.
・Water-dispersed silica sol A (manufactured by Nissan Chemical Co., Ltd., silica concentration 21% by mass, pH 3, average primary particle diameter 46 nm)
・Water-dispersed silica sol B (manufactured by Nissan Chemical Co., Ltd., silica concentration 30% by mass, pH 11, average primary particle diameter 46 nm)
・Water-dispersed silica sol C (manufactured by Nissan Chemical Co., Ltd., silica concentration 32% by mass, pH 3, average primary particle diameter 9 nm)
・Water-dispersed silica sol D (manufactured by Nissan Chemical Co., Ltd., silica concentration 30% by mass, pH 10, average primary particle diameter 17 nm)
・Methanol-dispersed silica sol a (see Synthesis Example 1-1)
・Methanol-dispersed silica sol b (see Synthesis Example 1-2)
・Methanol-dispersed silica sol c (see Synthesis Example 1-3)

[Surface modifier (silylated polymer, etc.)]
In addition, the surface modifiers used in Examples and Comparative Examples are as follows.
・Surface modifier A (see Synthesis Example 2-1)
・Surface modifier B (see Synthesis Example 2-2)
・Surface modifier C (see Synthesis Example 2-3)
・Surface modifier D (see Synthesis Example 2-4)
・Surface Modifier E (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM-7103, 3,3,3-trifluoropropyltrimethoxysilane, molecular weight 218, hydrolyzable functional group: methoxy group)

In accordance with the following methods, the physical properties of the water-dispersed silica sols A to D, the surface-modified silica particle dispersions prepared in Examples and Comparative Examples, and the silica sols and dispersions during the dispersion manufacturing process were measured and evaluated.

[Measurement of silica (SiO ₂ ) concentration]
The silica concentration of the water-dispersed silica sol, the methanol-dispersed silica sol, the silica sol during the manufacturing process of the methanol-dispersed silica sol, and the dispersion of surface-modified silica particles is determined by placing the silica sol or dispersion in a crucible and removing the solvent by heating. It was calculated by baking at ℃ and weighing the baking residue.

[Method for measuring pH of water-dispersed silica sol, etc.]
The pH of the silica sol during the manufacturing process of water-dispersed silica sol and methanol-dispersed silica sol is p
It was measured using an H meter (manufactured by Toa DKK Co., Ltd., MM-43X).

[Measurement of specific surface area and average primary particle diameter]
[Measurement of specific surface area (S _N2 ) by nitrogen adsorption method]
The specific surface area (S _N2 ) of the nitrogen adsorption method of silica particles in the silica sol during the production process of water-dispersed silica sol, methanol-dispersed silica sol, and methanol-dispersed silica sol is determined by・After removing the silica sol with Chemical Co., Ltd. (trade name: Amberlite IR-120B), the silica sol was dried at 290°C and used as a measurement sample, which was then measured using a nitrogen adsorption method specific surface area measuring device Monosorb (Quantachrome Instruments). (manufactured by Japan LLC).
[Average primary particle diameter]
The average primary particle diameter was calculated by converting the specific surface area S _N2 (m ² /g) obtained by the nitrogen adsorption method into spherical particles using the following calculation formula. The results are shown in Table 1.
Average primary particle diameter (nm) = 2720/S _N2 (m ² /g)

[Measurement of cations]
The metal components of the silica sol during the methanol-dispersed silica sol manufacturing process were measured using an atomic absorption spectrophotometer (manufactured by Shimadzu Corporation, AA-7000).
[Measurement of anions]
The base component of the silica sol during the methanol-dispersed silica sol manufacturing process was measured using an ion chromatograph (ICS-1600, manufactured by Thermo Fisher Scientific Co., Ltd.).

[Measurement of moisture content]
The water content of the surface-modified silica particle dispersion and the silica sol (methanol-dispersed silica sol) during its manufacturing process was determined by Karl Fischer titration using a Karl Fischer moisture meter (manufactured by Kyoto Electronics Industry Co., Ltd., trade name: MKA-610). Measured using the method.

[Measurement of number average molecular weight]
The number average molecular weights (Mn) of the polymers (surface modifiers) prepared in Synthesis Examples 2-1 to 2-4 below are the results of measurements by gel permeation chromatography (GPC). The measurement conditions are as follows. In addition, the molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) was determined by the same method.
GPC column: PLgel 5μm MIXED-D (manufactured by Agilent Technologies)
Column temperature: 40°C
Solvent: Tetrahydrofuran (THF)
Flow rate: 1.00ml/min Detector: RI detector Standard sample: Polystyrene

[MALTI-TOF-MS]
The MALDI-TOF-MS used for qualitative analysis of the polymers (surface modifiers) prepared in Synthesis Examples 2-1 to 2-4 below was manufactured by Bruker, and the matrix was trans-2-[3-( 4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB) and sodium trifluoroacetate were used as the ionizing agent.

[Calculation of equivalent weight of hydrolyzable functional group]
The equivalent weight of the hydrolyzable functional group (alkoxy group) in the polymer (surface modifier) prepared in the following Synthesis Examples 2-1 to 2-4 is the molecular weight of the polymer (surface modifier) obtained in the above average molecular weight measurement. It was calculated using the following formula 1 based on the hydrolyzable group species of the polymer (surface modifier). The results are shown in Table 1.
Equivalent weight of hydrolyzable functional groups (g/eq) = (molecular weight of surface modifier)/(number of hydrolyzable functional groups)...Formula 1

[Calculation of dipole force]
The dipole force of the polymers (surface modifiers) prepared in Synthesis Examples 2-1 to 2-4 below was calculated using solubility parameter calculation software (Hansen SP&QSPR model) based on the molecular weight and molecular structure information of the polymers (surface modifiers). , Winmostar V10, X-Ability
Co. Ltd. , Japan-Tokyo, 2020). The results are shown in Table 1.

[Organic solvent content]
The organic solvent content of the dispersion of surface-modified silica particles was determined by gas chromatography (GC-2014s, manufactured by Shimadzu Corporation).
Gas chromatography conditions:
Column: 3mm x 1m glass column Packing material: Polarpack Q
Column temperature: 130-230°C (temperature increase 8°C/min)
Carrier: _N2 40mL/min
Detector: FID
Injection volume: 1μL
Internal standard: acetonitrile was used.

[Measurement of dielectric constant and dielectric loss tangent]
Using a cavity resonator jig for a measurement frequency of 1 GHz (manufactured by Keycom Co., Ltd.), powder samples (Examples 2-1 to 2-8, described later) were placed in a PTFE sample tube (length 30 mm, inner diameter 3 mm). After filling with silica powder obtained in Comparative Examples 2-1 to 2-3, the dielectric constant and dielectric loss tangent of the measurement sample were measured using a vector network analyzer (product name: FieldFox N6626A, manufactured by KEYSIGHT TECHNOLOGIES) (23°C , frequency 1 GHz).
When the measured value of the dielectric loss tangent was 0.01 or less, the low dielectric property was evaluated as "OK", and when the measured value of the dielectric loss tangent exceeded 0.01, the low dielectric property was evaluated as "NG".

[Synthesis Example 1: Preparation of methanol-dispersed silica sol]
[Synthesis Example 1-1: Methanol-dispersed silica sol a]
2,500 g of water-dispersed silica sol A was charged into a glass reactor with an internal volume of 3 L equipped with a stirrer, a condenser, a thermometer, and two injection ports, and heated to boil the silica sol. While the silica sol in the reactor was kept boiling, methanol vapor generated in a separate boiler was continuously blown into the silica sol in the reactor to replace water as a dispersion medium with methanol. The substitution was completed when the water content of the methanol dispersion became 3.0% by mass or less, and 1,280 g of methanol-dispersed silica sol a was obtained.
The obtained methanol-dispersed silica sol a had a silica concentration of 41% by mass and a water content of 1.5% by mass.

[Synthesis Example 1-2: Methanol-dispersed silica sol b]
A SUS autoclave reactor with an internal volume of 300 cc was charged with 129 g of water-dispersed silica sol C and 121 g of water-dispersed silica sol D, and hydrothermal treatment was performed at 300±20° C. for 1 hour. Of the obtained sol, 100 g was mixed with 30 g of a hydrogen-type strongly acidic cation exchange resin (Amberlite (registered trademark) IR-120B, Organo Co., Ltd.), stirred for 30 minutes, and filtered to obtain an acidic silica sol. 100 g was obtained (pH 3, SiO ₂ concentration 20% by mass, average primary particle diameter 74 nm).
62 g of the obtained acidic silica sol was diluted to 130 g with methanol, and this was put into an evaporator equipped with a 1 L eggplant-shaped flask. Then, water was distilled off at 550 Torr while gradually adding methanol to obtain a dispersion medium. Water was replaced with methanol. The substitution was completed when the water content of the methanol dispersion became 1.0% by mass or less, and 155 g of methanol-dispersed silica sol b was obtained.
The obtained methanol-dispersed silica sol b had a silica concentration of 8% by mass and a water content of 0.5% by mass.

[Synthesis Example 1-3: Methanol-dispersed silica sol c]
250 g of water-dispersed silica sol B was charged into a SUS autoclave reactor having an internal volume of 300 cc, and hydrothermal treatment was performed at 230±10° C. for 2.5 hours. To 100 g of the obtained sol, an aqueous sodium sulfate solution diluted to 5% was added to give a concentration of 20 to 50 ppm in terms of SO ₃ , and then hydrogen-type strongly acidic cation exchange resin (Amberlite (registered trademark)) was added. It was mixed with 30 g of IR-120B (Organo Co., Ltd.), stirred for 30 minutes, and then filtered to obtain 130 g of acidic silica sol (pH 3, SiO ₂ concentration 23% by mass, average primary particle size 28 nm, Na ₂ O: 344 ppm, _SO3 30 ppm).
130 g of the obtained acidic silica sol was put into an evaporator equipped with a 1 L eggplant-shaped flask, and then water was distilled off at 550 Torr while gradually adding methanol, thereby replacing water as a dispersion medium with methanol. The substitution was completed when the water content of the methanol dispersion became 2.0% by mass or less, and 91 g of methanol-dispersed silica sol c was obtained.
The obtained methanol-dispersed silica sol c had a silica concentration of 33% by mass and a water content of 1.6% by mass.

[Synthesis Example 2: Synthesis of surface modifier (silylated polymer)]
FIG. 1 shows a schematic diagram of a flow reactor (reactor) used in Synthesis Examples 2-1 to 2-4 described below. Note that in FIG. 1, arrows indicate the direction in which the liquid flows.
A plunger pump A (manufactured by Fromm Co., Ltd., UI-22-410S) was used to feed the styrene solution, and a PTFE tube (inner diameter 1.0 mm, outer diameter 1.6 mm, length 2 m) was used to pump the plunger. Pump A and one inlet of mixer 1 were connected. In addition, a diaphragm pump B (manufactured by Takumina Co., Ltd., Smooth Flow Pump Q-30-PEEK) was used to feed the initiator solution, and a PTFE tube (inner diameter 1.0 mm, outer diameter 1.6 mm, length 2 m) was used. was used to connect diaphragm pump B and the other inlet of mixer 1. The outlet of mixer 1 and one inlet of mixer 2 were connected with a PFA tube (inner diameter 2.0 mm, outer diameter 3 mm, length 2 m). At the other inlet of mixer 2, a PTFE tube (inner diameter 1.0 mm, outer diameter 1.6 mm, length 2 m) was connected to a plunger pump C (manufactured by From Co., Ltd.) for feeding the polymerization terminator. , UI-22-110S) was connected. A PFA tube (inner diameter 2.0 mm, outer diameter 3 mm, length 2 m) was connected to the outlet of mixer 2.
In addition, the flow path from pumps A, B, and C to 90% of the length of the tube connected to the outlet of mixer 2 (the part surrounded by □ in Fig. 1) was heated to 10°C (in Fig. 1, The temperature was adjusted by immersing it in a constant temperature bath (expressed as T°C).

Mixers 1 and 2 used in the synthesis were a two-liquid mixing mixer with a double pipe structure described in International Publication No. 2017/135398 [the joint member and the cylindrical body were made of stainless steel, and a static mixer] As the element body, DSP-MXA3-17 manufactured by Noritake Company Limited (polyacetal element, number of twisting blades 17, diameter 3 mm) was used.
The connection to each mixer was as follows: a styrene solution tube was connected to the inlet of the introduction hole of mixer 1, and an initiator solution tube was connected to the inlet of the inner pipe. A tube connected to the outlet of mixer 1 was connected to the inlet of the introduction hole of mixer 2, and a polymerization terminator liquid feeding tube was connected to the inlet of the inner tube.

<Synthesis Example 2-1/Synthesis of terminal propyltriethoxysilane polystyrene/Surface modifier A>
A 1.30 mol/L styrene THF solution and a toluene/hexane solution of 0.15 mol/L n-butyllithium as an initiator were mixed in mixer 1 at a flow rate of 30.0 mL/min and 6.0 mL/min, respectively. Polymerized.
Subsequently, 3-chloropropyltriethoxysilane liquid was mixed as a polymerization terminator at 1.07 mL/min using mixer 2 to terminate the polymerization. Each pump was pumped for 7 minutes and the effluent was collected.

Furthermore, the effluent was added dropwise to a mixed solution of 2300 mL of methanol, and the resulting white suspension was filtered through a 1.0 μm membrane filter and washed with 400 mL of methanol. Subsequently, the obtained white solid was dried under reduced pressure (50° C., 5 hours) to obtain 27.4 g of terminal propyltriethoxysilane polystyrene.
When the obtained polymer (surface modifier A) was analyzed by GPC, Mn=5,445 and Mw/Mn=1.09. Furthermore, the results of MALDI-TOF-MS measurement are shown in FIG. 2, and the results of ¹ H-NMR of the polymer are shown in FIG. From these results, it was confirmed that propyltriethoxysilane was introduced at the end of polystyrene.

<Synthesis Example 2-2/Synthesis of terminal propyltriethoxysilane polystyrene/Surface modifier B>
Styrene THF solution concentration is 0.50 mol/L, solution concentration of the initiator is 0.22 mol/L, and 3-chloropropyltriethoxysilane solution is mixed at 1.54 mL/min with mixer 2 as a polymerization terminator, and the effluent is mixed. Synthesis was carried out in the same manner as in Synthesis Example 1, except that the collection time was changed to 20 minutes, to obtain 29.2 g of terminal propyltriethoxysilane polystyrene.
When the obtained polymer (surface modifier B) was analyzed by GPC, Mn=1,848 and Mw/Mn=1.14. Furthermore, from the results of MALDI-TOF-MS of the polymer, it was confirmed that propyltriethoxysilane was introduced at the polystyrene end.

<Synthesis Example 2-3/Synthesis of terminal propyltriethoxysilane polystyrene/Surface Modifier C>
Styrene THF solution concentration is 0.40 mol/L, solution concentration of the initiator is 0.33 mol/L, and 3-chloropropyltriethoxysilane solution is mixed at 1.84 mL/min with mixer 2 as a polymerization terminator, and the effluent is mixed. Synthesis was carried out in the same manner as in Synthesis Example 1, except that the sampling time was changed to 32 minutes, to obtain 15.0 g of terminal propyltriethoxysilane polystyrene.
When the obtained polymer (surface modifier C) was analyzed by GPC, Mn=1,353 and Mw/Mn=1.15. Furthermore, from the results of MALDI-TOF-MS of the polymer, it was confirmed that propyltriethoxysilane was introduced at the polystyrene end.

<Synthesis Example 2-4/Synthesis of terminal propyltrimethoxysilane polystyrene/Surface modifier D>
Styrene THF solution concentration is 0.40 mol/L, solution concentration of the above-mentioned initiator is 0.33 mol/L, and 3-chloropropyltrimethoxysilane solution is mixed at 1.84 mL/min with mixer 2, and the effluent is Synthesis was carried out in the same manner as in Synthesis Example 1, except that the sampling time was changed to 11 minutes, and 7.6 g of terminal propyltrimethoxysilane polystyrene was obtained.
When the obtained polymer (surface modifier D) was analyzed by GPC, Mn=1,240 and Mw/Mn=1.22. Furthermore, the results of MALDI-TOF-MS measurement are shown in FIG. 4, and the results of ¹ H-NMR of the polymer are shown in FIG. From these results, it was confirmed that propyltrimethoxysilane was introduced at the end of polystyrene.

[Example 1/Preparation of surface-modified silica particles]
[Example 1-1]
(i) Step: 27.0 g of methyl ethyl ketone was placed in a 200 cc eggplant-shaped flask, and while stirring with a magnetic stirrer, 0.65 g of surface modifier A obtained in Synthesis Example 2-1 was added. After confirming that the added surface modifier A was dissolved, 30.0 g of methanol-dispersed silica sol a obtained in Synthesis Example 1-1 was added dropwise, heated to 60°C and held for 8 hours, and the surface modified silica sol was dissolved. A methanol dispersion of particles was prepared. The total amount of surface modifier A added was 0.1 particles per 1 nm ² of surface area of silica particles in the sol.

(ii) Step: After that, the eggplant-shaped flask containing the methanol dispersion of surface-modified silica particles was set in a rotary evaporator, and the water content of the methyl ethyl ketone dispersion was reduced to 1.5% under a bath temperature of 80°C and a reduced pressure of 600 to 400 Torr. Distillation was performed while supplying methyl ethyl ketone until it became 0% by mass or less, and the dispersion medium was replaced with methyl ethyl ketone to obtain a methyl ethyl ketone dispersion of surface-modified silica particles.
The resulting methyl ethyl ketone dispersion of surface-modified silica particles had a silica concentration of 23% by mass, a water content of 0.1% by mass, and a methanol content of 0.8% by mass or less.

[Example 1-2]
Instead of surface modifier A in step (i) of Example 1-1, 0.1 surface modifier B obtained in Synthesis Example 2-2 was added per 1 nm ² of surface area of silica particles contained in the silica sol. (Total amount) Except for the above, operations were carried out in the same manner as steps (i) to (ii) of Example 1-1 to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles. did.

[Example 1-3]
Instead of surface modifier A in step (i) of Example 1-1, 0.5 pieces of surface modifier B obtained in Synthesis Example 2-2 were added per 1 nm ² of surface area of silica particles contained in the silica sol. (Total amount) Except for the above, operations were carried out in the same manner as steps (i) to (ii) of Example 1-1 to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles. did.

[Example 1-4]
Instead of surface modifier A in step (i) of Example 1-1, 1.0 pieces of surface modifier B obtained in Synthesis Example 2-2 was added per 1 nm ² of surface area of silica particles contained in the silica sol. (Total amount) Except for the above, operations were carried out in the same manner as steps (i) to (ii) of Example 1-1 to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles. did.

[Example 1-5]
Instead of surface modifier A in step (i) of Example 1-1, 0.5 pieces of surface modifier C obtained in Synthesis Example 2-3 was added per 1 nm ² of surface area of silica particles contained in the silica sol. (Total amount) Except for the above, operations were carried out in the same manner as steps (i) to (ii) of Example 1-1 to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles. did.

[Example 1-6]
Instead of surface modifier A in step (i) of Example 1-1, 0.5 pieces of surface modifier D obtained in Synthesis Example 2-4 was added per 1 nm ² of surface area of silica particles contained in the silica sol. (Total amount) Except for the above, operations were carried out in the same manner as steps (i) to (ii) of Example 1-1 to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles. did.

[Example 1-7]
Instead of methanol-dispersed silica sol a and surface modifier A in step (i) of Example 1-1, methanol-dispersed silica sol b obtained in Synthesis Example 1-2 and surface modifier obtained in Synthesis Example 2-2 were used. B was prepared in the same manner as in steps (i) to (ii) of Example 1-1, except that 0.5 pieces (total amount) of surface modifier B were added per 1 nm ² of surface area of silica particles contained in the silica sol. The operation was carried out to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles.

[Example 1-8]
Instead of methanol-dispersed silica sol a and surface modifier A in step (i) of Example 1-1, methanol-dispersed silica sol c obtained in Synthesis Example 1-3 and surface modifier obtained in Synthesis Example 2-2 were used. B was prepared in the same manner as in steps (i) to (ii) of Example 1-1, except that 0.5 pieces (total amount) of surface modifier B were added per 1 nm ² of surface area of silica particles contained in the silica sol. The operation was carried out to prepare a methanol dispersion of surface-modified silica particles and a methyl ethyl ketone dispersion of surface-modified silica particles.

[Comparative example 1-1]
The acidic silica sol obtained in Synthesis Example 1-3 was used as Comparative Example 1-1.

[Comparative example 1-2]
200 g of methanol-dispersed silica sol C was placed in a 300 cc eggplant-shaped flask, and while stirring with a magnetic stirrer, 2.4 g of surface modifier E was added in an amount of 1.0 particles per 1 nm ² of surface area of silica particles. The mixture was heated to and held for 3 hours to prepare a methanol dispersion of surface-modified silica particles.

[Example 2/Evaluation of dielectric properties of surface-modified silica particles]
[Example 2-1]
The dispersion of surface-modified silica particles obtained in Example 1-1 was dried in a vacuum dryer at 100°C to remove the dispersion solvent. The obtained silica gel was crushed in a mortar and then dried at 150° C. for 1 hour to produce silica powder.
Regarding the obtained silica powder, the dielectric constant and dielectric loss tangent of the silica powder at 23° C. and a frequency of 1 GHz were measured. Table 1 shows the dielectric properties of the surface-modified silica particles.

[Example 2-2 to Example 2-8, Comparative Example 2-1 to Comparative Example 2-2]
The dispersions of surface-modified silica particles or surface-unmodified particles (Comparative Example 1-1) obtained in Examples 1-2 to 1-8 and Comparative Example 1-2 were treated in the same manner as in Example 2-1. Silica powder was produced and its dielectric constant and dielectric loss tangent were measured. Table 1 shows the dielectric properties of each silica particle.

As shown in Table 1, silica particles whose particle surfaces were modified with a surface modifier having a number average molecular weight Mn of 500 to 100,000 and a dipole force of 0.01 to 2.0 (MPa) ^{1/ 2} , or the equivalent weight of the hydrolyzable functional group is 150 to 4.
,000 (g/eq) in Examples 2-1 to 2-8, which are silica particles modified with a surface modifying agent, the value of the dielectric loss tangent at a frequency of 1 GHz is 0.02 or less. It was confirmed that these silica particles exhibit very excellent low dielectric properties.

On the other hand, silica particles that are not coated with a surface modifier (Comparative Example 1-1) or silica particles modified with a surface modifier but in which the surface modifier has an average molecular weight of less than 1,000 (Comparative Example 1-1) Example 1-2), or the dipole force exceeds 2 (Comparative Example 1-2), or the equivalent of the hydrolyzable functional group is less than 150 (Comparative Example 1-2), the dielectric loss tangent is The value was larger than 0.02, indicating that the silica particles had poor dielectric properties.

The present invention can reduce the dielectric loss tangent value of silica particles coated with a conventional surface modifier having an average molecular weight of less than 1000 or a hydrolyzable functional group equivalent of less than 150 by more than 30%. Therefore, it can be expected to be applied to high frequency applications.

Claims (17)

Particles in which at least a part of the particle surface is coated with a silylated polymer or bonded to at least a part of the particle surface, the average primary particle diameter is 5 to 1000 nm, and the dielectric loss tangent at 1 GHz is Surface-modified silica particles having a particle size of 0.02 or less. The surface-modified silica particles according to claim 1, wherein the silylated polymer has a structural unit represented by formula (1) and a structural unit represented by formula (2).

(In the formula,
X indicates a bond,
R ¹ represents a hydrogen atom or a methyl group,
^R2 is a substituent for a hydrogen atom, and is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, or an acryloyl group, a methacryloyl group, a mercapto group, or an amino group. , an organic group having an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
a represents an integer from 0 to 5,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
^R4 is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, an organic group having a cyano group, or a combination thereof,
A ¹ represents a hydrocarbon group having 1 to 10 carbon atoms,
b represents an integer from 1 to 3, c represents 3-b,
d represents an integer from 1 to 4. ) The surface-modified silica particle according to claim 1, wherein the silylated polymer includes a structural unit represented by formula (3).

(In the formula,
R ¹ represents a hydrogen atom or a methyl group,
R ² is a substituent for a hydrogen atom, and each independently represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, or a mercapto group. , an organic group having an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
R ⁴ is each independently an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, or a hydroxy group. group, an alkoxy group, an ester group, a sulfonyl group, or an organic group having a cyano group, or a combination thereof,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
A ² represents a hydrocarbon group having 1 to 10 carbon atoms,
a represents an integer from 0 to 5, b represents an integer from 1 to 3, and c represents 3-b. ) The surface-modified silica particle according to claim 1, wherein the silylated polymer includes a structural unit represented by formula (4).

(In the formula,
R ¹ represents a hydrogen atom or a methyl group,
R ² is a substituent for a hydrogen atom, and each independently represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, or a mercapto group. , an organic group having an amino group, an amide group, a hydroxy group, an alkoxy group, an ester group, a sulfonyl group, or a cyano group, or a combination thereof,
R ⁴ is each independently an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkoxyaryl group, an alkenyl group, an acyloxyalkyl group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group, an amide group, or a hydroxy group. group, an alkoxy group, an ester group, a sulfonyl group, or an organic group having a cyano group, or a combination thereof,
R ³ represents an alkoxy group, an acyloxy group, or a halogen group,
a represents an integer from 0 to 5,
b indicates an integer from 1 to 3, c indicates 3-b) the silylated polymer has a number average molecular weight of 500 to 100,000;
The surface-modified silica particles according to any one of claims 1 to 4. The silylated polymer has a molecular weight distribution (Mw/Mn) = 1 to 2,
The surface-modified silica particles according to claim 5. the silylated polymer is bonded to the surface of at least a portion of the silica particles through a covalent bond;
The surface-modified silica particles according to any one of claims 1 to 6. The silylated polymer is bonded at a rate of 0.1 to 1.5/nm ² per 1 square nm of the surface area of the silica particle.
The surface-modified silica particles according to claim 7. The surface-modified silica according to any one of claims 1 to 8, which is coated with a surface modifier made of a silylated polymer that satisfies the following (i) or (ii) and has a hydrolyzable functional group. particle.
(i) The dipole force of the surface modifier is 0.01 to 2.0 (MPa) ^1/2 .
(ii) The equivalent weight of the hydrolyzable functional group of the surface modifier or the equivalent weight of the hydroxy group derived from the hydrolyzable functional group is 150 to 4000 (g/eq). The surface-modified silica particles according to any one of claims 1 to 9 contain at least one type selected from water, alcohols, ketones, hydrocarbons, amides, esters, ethers, and amines. Silica sol dispersed in a solvent. The following steps (A) to (C):
(A) Step: preparing a silica sol using silica particles having an average primary particle diameter of 5 to 1000 nm as a dispersoid and an alcohol having 1 to 4 carbon atoms as a dispersion medium;
(B) Step: A compound represented by the above formula (3) or formula (4) dissolved in at least one solvent selected from alcohols, ketones, hydrocarbons, amides, esters, ethers, or amines. a step of heating and stirring the silylated polymer and the silica sol of step (A) at 40 to 80°C for 0.1 to 10 hours;
(C) step: a step of removing the solvent from the silica sol after step (B);
including,
The method for producing silica particles according to claim 3 or 4. Either or both of step (B) and step (C) are performed under reduced pressure.
The method for producing silica particles according to claim 11. The method for producing silica particles according to claim 11, wherein the silica sol prepared in step (A) contains 0.01 to 10% by mass of water. The silica sol prepared in step (A) is a silica sol obtained by replacing the aqueous silica sol hydrothermally synthesized at 200 to 380 ° C. and 2 MPa to 22 MPa with an alcohol having 1 to 4 carbon atoms.
The method for producing silica particles according to claim 11. A composite material in which the surface-modified silica particles according to any one of claims 1 to 9 are combined with an organic resin. The organic resin is styrene resin, epoxy resin, cyanate resin, benzoxazine, phenol resin, acrylic resin, maleimide resin, urethane resin, polyimide, polytetrafluoroethylene, cycloolefin polymer, unsaturated polyester, vinyl triazine, crosslinkable polyphenylene. The composite material according to claim 15, which is at least one member selected from the group consisting of oxide and curable polyphenylene ether. 17. The method according to claim 15 or 16, having an application selected from the group consisting of semiconductor device materials, copper-clad laminates, integrated circuits, flexible wiring materials, flexible display materials, antenna materials, optical wiring materials, and sensing materials. Composite material.