WO2023032986A1

WO2023032986A1 - Silica for electronic materials and method for producing same

Info

Publication number: WO2023032986A1
Application number: PCT/JP2022/032603
Authority: WO
Inventors: 弘樹谷川; 泰之村上
Original assignee: 堺化学工業株式会社
Priority date: 2021-08-31
Filing date: 2022-08-30
Publication date: 2023-03-09
Also published as: TW202323193A; KR20240054278A; JPWO2023032986A1

Abstract

The purpose of the present invention is to provide a silica which has a low dielectric loss tangent and excellent uniform dispersibility in a resin, while achieving high safety. The present invention relates to a material for forming a filler for electronic materials, the material containing an amorphous silica wherein the peak intensity ratio (A/B) of a peak A derived from an isolated hydroxyl group to a peak B derived from a hydroxyl group forming a hydrogen bond is 1.0 to 75.0, and there is substantially no peak derived from adsorbed water in the range from 3,500 to 3,100 cm^-1 in an FT-IR measurement.

Description

Silica for electronic materials and its production method

TECHNICAL FIELD The present invention relates to silica for electronic materials and a method for producing the same.

Information communication technology is an indispensable technology in the present age when a large amount of information is exchanged in various fields of society. In recent years, in order to enable a larger amount of information communication, the use of 5G communication, which uses radio waves in a higher frequency band instead of the conventional 4G communication and is capable of communicating a large amount of information, is spreading. Higher frequencies are also being used in electronic devices used for mobile phones.
As the frequency of electronic devices increases, a material with a low dielectric loss tangent is also required for the inorganic filler of resins used in the manufacture of electronic devices, and silica is attracting attention as such a material.
Silica used in conventional electronic devices includes fused spherical silica powder after dielectric loss tangent reduction treatment (see Patent Document 1), silica particles with specified particle size distribution, specific surface area and dielectric loss tangent (see Patent Document 2). etc. are disclosed. Further, as a method for producing silica used for electronic material applications, the steps of preparing a silica particle material by a dry method, first surface-treating the silica particle material with a silane compound having a predetermined functional group, A method for producing a filler for an electronic material comprising a second surface treatment step of surface-treating the treated material particles with a predetermined amount of organosilazane (see Patent Document 3), isolated silanol group content, specific surface area ratio to theoretical surface area is predetermined A method for producing hydrophobic silica particles is disclosed in which an organosilylating agent is reacted with silica, which is a value (see Patent Document 4).

Japanese Patent No. 6793282 Japanese Unexamined Patent Application Publication No. 2021-70592 Japanese Patent No. 6564517 JP 2010-228997 A

In recent years, there has been a demand for electronic devices to have both higher frequencies and smaller size. In order to reduce the size and thickness of electronic materials that use resin compositions containing inorganic fillers, it is necessary for the inorganic fillers used to be uniformly dispersed in the resin. Both uniform dispersibility in the resin is required. However, with conventional low dielectric loss tangent silica, as a result of pursuing the reduction of isolated hydroxyl groups that cause dielectric loss, the surface treatment agent and silica cannot bond well, resulting in insufficient dispersibility in resin. I have a problem. If the dispersibility in the resin is insufficient, the viscosity increases during kneading with the resin and lumps are generated, making it difficult to meet the demand for thin-film electronic materials that achieve high frequency and miniaturization. Inorganic fillers are also required to be highly safe from the point of handleability.

SUMMARY OF THE INVENTION An object of the present invention is to provide silica having a low dielectric loss tangent, excellent uniform dispersibility in a resin, and high safety.

The present inventors have studied silica, which has a low dielectric loss tangent, is excellent in uniform dispersibility in resin, and has high safety. It was found that isolated hydroxyl groups on the surface of silica, which had been thought to be reduced as much as possible from the point of view, do not significantly affect the loss factor up to a certain amount. Then, we investigated silica that can achieve both good dielectric properties and dispersibility in resin, and found that amorphous silica that satisfies predetermined requirements in FT-IR measurement has good dielectric properties and dispersibility in resin. It is suitable as a raw material for surface-treated silica that is compatible with each other, and the surface-treated silica obtained by treating the silica with a surface treatment agent is suitable as an inorganic filler for use in electronic devices that use high-frequency radio waves. And, unlike carcinogenic crystalline silica, amorphous silica has no problem in terms of safety.
The present inventors have also found a suitable method for producing surface-treated silica that has such good dielectric properties, is excellent in uniform dispersibility in resins, and has high safety, and has completed the present invention. rice field.

That is, the present invention is as follows.
[1] The peak intensity ratio (A/B) between the peak A derived from an isolated hydroxyl group and the peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement is 1.0 to 75.0, and , 3500 to 3100 cm ⁻¹ , a material for producing a filler for an electronic material containing amorphous silica in which there is substantially no peak derived from adsorbed water.

[2] The material for producing a filler for an electronic material according to [1], wherein the silica has a D50 of 10 µm or less and a D10/D90 of 0.30 or more in a laser diffraction particle size distribution.

[3] The silica has a powder ratio of tan δ to BET specific surface area (tan δ/BET specific surface area) at 1 GHz and 10 GHz, both of which is 1.0 × 10 ^-3 or less [1] or [ 2].

[4] The silica has a peak intensity ratio (A/B) between a peak A derived from an isolated hydroxyl group and a peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement of 1.0 to 10.0. The material for producing a filler for an electronic material according to any one of [1] to [3], characterized in that:

[5] Amorphous surface-treated silica treated with a surface treatment agent, wherein the surface-treated silica has a powder tan δ of 1.0 × 10 ^-3 or less at 1 GHz and an ε of 3.15. tan δ of the powder at 10 GHz is 3.0 × 10 ^-3 or less, ε is 3.15 or less, and the viscosity at 25 ° C. measured under the following conditions is 75000 mPa s or less. Amorphous surface-treated silica characterized by:
(conditions)
Using the amorphous surface-treated silica and an epoxy resin having a viscosity of 11000 to 15000 mPa s at 25 ° C., the mass ratio of the amorphous surface-treated silica to the epoxy resin (amorphous surface-treated silica: epoxy Resin) is kneaded at a ratio of 4:6 to prepare a resin mixture for affinity evaluation, and the viscosity at 25° C. of the obtained resin mixture for affinity evaluation is measured using a Brookfield viscometer.

[6] Amorphous surface-treated silica treated with a surface treatment agent, wherein the surface-treated silica has a powder tan δ of 1.0 × 10 ^-3 or less at 1 GHz and an ε of 3.15 below, the tan δ of the powder at 10 GHz is 3.0 × 10 ^-3 or less, and the ε is 3.15 or less, and a hydrogen bond is formed with the peak A derived from the isolated hydroxyl group in the FT-IR measurement. A surface-treated silica having a peak intensity ratio (A/B) of 0.50 or less to a peak B derived from a hydroxyl group present.

[7] A resin composition for electronic materials, comprising the surface-treated silica according to [5] or [6] and a resin.

[8] An electronic material produced using the resin composition for electronic materials according to [7].

[9] A method for producing surface-treated silica, which comprises a step of firing amorphous silica obtained by a sol-gel method at 600 to 1200 ° C., A step of crushing, if necessary, a step of re-firing the crushed fired silica obtained in the crushing step at 700 to 1200 ° C., and the crushed fired silica obtained in the crushing step or A method for producing surface-treated silica, comprising a step of treating the refired silica obtained in the refired step with a surface treatment agent.

The material for producing a filler for an electronic material of the present invention is a highly safe material that can produce surface-treated silica with a low dielectric loss tangent and excellent uniform dispersibility in resin, and uses radio waves in a high frequency band. It can be suitably used as a raw material for inorganic fillers used in electronic devices.

1 is a diagram showing FT-IR measurement results of refired silica 1 produced in Example 1. FIG. 2 is a diagram showing the FT-IR measurement results of refired silica 2 produced in Example 2. FIG. 4 is a diagram showing the FT-IR measurement results of comparative refired silica 1 produced in Comparative Example 1. FIG. 3 is a diagram showing the FT-IR measurement results of comparative pyrogenic silica 2 produced in Comparative Example 2. FIG. FIG. 2 is a view showing the FT-IR measurement results of refired silica 1 and 2 produced in Examples 1 and 2 and comparative refired silica 1 and comparative calcined silica 2 produced in Comparative Examples 1 and 2, respectively.

Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description, and can be appropriately modified and applied without changing the gist of the present invention.

1. Materials for producing fillers for electronic materials The materials for producing fillers for electronic materials of the present invention show, in FT-IR measurement, a peak A derived from an isolated hydroxyl group appearing at 3800 to 3700 cm ⁻¹ and a hydrogen bond appearing at 3700 to 3600 cm ⁻¹ . The peak intensity ratio (A/B) with the peak B derived from the formed hydroxyl group is 1.0 to 75.0, and there is substantially no peak derived from adsorbed water at 3500 to 3100 cm ^-1 Non- It is characterized by containing crystalline silica.
The present inventor believes that if water is adsorbed to silica, it will adversely affect the dielectric properties, so it is preferable ^not to have adsorbed water. , 3700 to 3600 cm ⁻¹ , if the ratio of the peak B derived from the hydroxyl group forming the hydrogen bond appearing at 3700 to 3600 cm −1 is within a certain range, the dielectric loss tangent is low and the dielectric properties are excellent even if it has a hydroxyl group, and the surface treatment It was found that silica can be sufficiently bonded to the agent. Therefore, by reacting a material containing such silica with a surface treatment agent, a surface-treated silica having a low dielectric loss tangent, excellent uniform dispersibility in resin, and suitable for use as an inorganic filler can be obtained. be able to. In addition, unlike crystalline silica, which is carcinogenic, amorphous silica free from such problems can be safely handled as a material for surface-treated silica.
If the peak intensity ratio (A/B) between the peak A derived from an isolated hydroxyl group in the FT-IR measurement of the silica and the peak B derived from a hydroxyl group forming a hydrogen bond is 1.0 to 75.0 Good, but preferably between 1.0 and 60.0. More preferably, it is 5.0 to 25.0.
The silica has substantially no peak derived from adsorbed water at 3500 to 3100 cm ^-1 in FT-IR measurement, but "substantially does not exist" is detected in peak analysis in FT-IR. When the lower limit is 0.01 and the sensitivity is 5, it means that detection is not possible. If the lower limit of detection and sensitivity are further lowered, noise in the measurement will be detected as a peak.
The above silica is amorphous, and the term "amorphous silica" in the present invention means silica for which no peak is detected at 20 to 30° in the XRD measurement result analysis. Peak detection is performed by automatic analysis using analysis software with a σ cut value of 3.0.

The silica forms a hydrogen bond with the peak A derived from an isolated hydroxyl group in the FT-IR measurement of the surface-treated silica obtained by surface-treating the silica with a surface-treating agent of 0.1 to 30% by mass. It is one of preferred embodiments of the present invention that the peak intensity ratio (A/B) to peak B derived from hydroxyl groups is 0.50 or less.
The silica of the present invention is used as an inorganic filler after being surface-treated by reacting with a surface treatment agent. A treated silica is obtained. Such surface-treated silica, which has few isolated hydroxyl groups on the surface, has a low dielectric loss tangent and excellent uniform dispersibility in resin, and also has excellent moisture resistance because there are few isolated hydroxyl groups that act as water adsorption sites. becomes.
Peak A derived from isolated hydroxyl groups in FT-IR measurement of surface-treated silica obtained by surface treatment with a surface treatment agent of 0.1 to 30% by mass with respect to the silica, and derived from hydroxyl groups forming hydrogen bonds The peak intensity ratio (A/B) to peak B is more preferably 0.40 or less. More preferably, it is 0.30 or less.

The silica has a peak intensity ratio (A/B) of 1.0 to 10.0 between a peak A derived from an isolated hydroxyl group and a peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement. is one of the preferred embodiments of the present invention. As described above, the surface-treated silica having few isolated hydroxyl groups on the surface has a low dielectric loss tangent, excellent uniform dispersibility in resin, and excellent moisture resistance. Silica having a peak intensity ratio (A/B) of 1.0 to 10.0 between peak A derived from an isolated hydroxyl group and peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement has a surface treatment. Most of the isolated hydroxyl groups on the surface are consumed by the reaction with the agent, and the resulting surface-treated silica has excellent moisture resistance. The peak intensity ratio (A/B) between the peak A derived from an isolated hydroxyl group and the peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement is more preferably 1.0 to 8.0. , more preferably 1.0 to 5.0.

The silica preferably has a D50 of 10 μm or less and a D10/D90 of 0.30 or more in a laser diffraction particle size distribution. By using silica having a small particle size and a narrow particle size distribution as a material, the composition obtained by blending the obtained surface-treated silica with a resin is more suitable for forming a thin film. A molded article formed using the composition has a higher surface flatness.
D50 of the silica is more preferably 5 μm or less, and still more preferably 2 μm or less. Although the lower limit of D50 of silica is not particularly limited, it is usually 0.005 μm or more.
The D10/D90 of the silica is more preferably 0.40 or more, still more preferably 0.60 or more, particularly preferably 0.70 or more, and most preferably 0.75 or more. is.

Further, the silica is preferably one having a maximum volume frequency of 15% or more in a laser diffraction particle size distribution. By using such silica, the molded article formed using the composition obtained by blending the obtained surface-treated silica with the resin has a higher surface flatness. Contribute to performance improvement.
The maximum volume frequency of the silica is more preferably 20% or more, still more preferably 30% or more, particularly preferably 40% or more, and most preferably 45% or more.

The above silica is obtained by analyzing a total of 100 or more particles in two or more different fields of view in SEM observation using image analysis software Azokun (manufactured by Asahi Kasei Engineering Co., Ltd.), and the maximum possible diameter of each particle Of the (maximum diameter) d, the ratio (dmax/d50) between the maximum particle diameter dmax and the average particle diameter d50 is preferably 5.0 or less.
As described above, silica having a small particle size and a narrow particle size distribution is preferable as a material for the surface-treated silica. By confirming the particle size of silica by SEM observation, it is possible to obtain a more accurate average particle size (average primary particle size) d50 of silica particles excluding agglomerated particles. By using silica whose dmax/d50 obtained from SEM images is 5.0 or less, a molded article formed using a composition obtained by blending the obtained surface-treated silica with a resin has higher surface flatness. As a result, the dielectric properties become more uniform, contributing to the improvement of the performance of electronic materials.
dmax/d50 is more preferably 2.5 or less, and still more preferably 1.8 or less. Although the lower limit of dmax/d50 is not particularly limited, it is usually 1.01 or more.
The average particle diameter d50 obtained from the SEM image is the average value of the particle diameters of 100 or more silica particles automatically extracted from the SEM image by image analysis software.
A method for determining the maximum particle size dmax and the average particle size d50 of silica from SEM observation is as described in Examples below.
In this specification, the particle size obtained by laser diffraction particle size distribution is indicated by "D", and the particle size obtained by SEM observation is indicated by "d".

The silica preferably has a BET specific surface area of 0.5 m ² /g or more. With such a specific surface area, the average particle size is relatively small, so it is suitable for thin film applications. The BET specific surface area of the silica is more preferably 1 m ² /g or more, still more preferably 2 m ² /g or more. Although the upper limit of the BET specific surface area of silica is not particularly limited, it is usually 300 m ² /g or less.

The above silica has a ratio of tan δ of powder to BET specific surface area of silica before surface treatment (tan δ/BET specific surface area) at 1 GHz and 10 GHz, both 1.0 × 10 ^-3 or less, and ε both 3.15 or less. is preferably
An object of the present invention is to provide amorphous surface-treated silica particles having a low dielectric loss tangent and excellent uniform dispersibility in a resin. In order to provide the surface-treated silica particles, the peak intensity ratio A / B between the peak A derived from the isolated hydroxyl group on the silica surface and the peak B derived from the hydroxyl group forming a hydrogen bond must be within a predetermined range. However, the material for producing surface-treated silica particles with low dielectric loss is desired not only to have an appropriate strength ratio A / B, but also to have a low dielectric loss tangent as a characteristic of the silica particles themselves. .
As mentioned above, the isolated hydroxyl groups on the silica surface affect the dielectric properties of silica. Since the amount of isolated hydroxyl groups tends to increase as the specific surface area of silica increases, the dielectric loss tangent value tends to increase as the specific surface area of silica increases. On the other hand, by obtaining tan δ per unit specific surface area, it is possible to evaluate the dielectric properties of the material itself, excluding the influence of the size of the specific surface area. When silica having a powder tan δ/BET specific surface area at 1 GHz and 10 GHz of 1.0 × 10 ^-3 or less and a dielectric constant ε of both 3.15 or less is used as a material, dielectric properties and resin It is possible to obtain a surface-treated silica excellent in both uniform dispersibility.
The value of (tan δ/BET specific surface area) of silica at 1 GHz and 10 GHz is preferably 1.0×10 ⁻³ or less. More preferably, it is 9.0×10 ⁻⁴ or less, and still more preferably 5.0×10 ⁻⁴ or less. Although the lower limit of the value of (tan δ/BET specific surface area) at 1 GHz and 10 GHz is not particularly limited, it is usually 1.0×10 ⁻⁶ or more.
The relative dielectric constant ε of the silica powder at 1 GHz and 10 GHz is more preferably 2.9 or less, and still more preferably 2.8 or less. Although the lower limit of the dielectric constant ε of the powder at 1 GHz is not particularly limited, it is usually 1.0 or more.
The value of tan δ and the relative permittivity ε of silica at 1 GHz and 10 GHz can be measured by the methods described in Examples below.

In the filler-producing material of the electronic material of the present invention, the peak intensity ratio (A/B) between the peak A derived from an isolated hydroxyl group and the peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement is 1.0. 0 to 75.0 and as long as it contains amorphous silica with substantially no peak derived from adsorbed water at 3500 to 3100 cm ⁻¹ , other components may be contained. Other components include metal elements such as Ti, Zr, Zn, Ba, Sr, and Ca, and light elements such as B, C, and N, either singly or as compounds.
The ratio of other components contained in the filler-producing material of the electronic material of the present invention is preferably 50% by mass or less with respect to 100% by mass of the filler-producing material of the electronic material. More preferably, it is 20% by mass or less, and still more preferably 10% by mass or less.

Further, the silica contained in the material for producing the filler of the electronic material of the present invention has a number of water molecules desorbed at 500° C. to 1000° C. when the temperature is raised from 25° C. to 1000° C. at a rate of 30° C./min. More than 010 mmol/g is preferred. More preferably, it is greater than 0.011 mmol/g.
Such silica can be obtained by carrying out the steps up to the surface treatment step in the method for producing surface-treated silica, which will be described later.

2. Surface-treated Silica The surface-treated silica of the present invention has a powder tan δ of 1.0×10 ⁻³ or less at 1 GHz, an ε of 3.15 or less, and a powder tan δ of 3.0×10 ⁻³ or less at 10 GHz. and an ε of 3.15 or less, and a viscosity of 75000 mPa s or less at 25° C. measured under the following conditions (hereinafter referred to as the first Also referred to as the surface-treated silica of the present invention).
(conditions)
Using the amorphous surface-treated silica and an epoxy resin having a viscosity of 11000 to 15000 mPa s at 25 ° C., the mass ratio of the amorphous surface-treated silica to the epoxy resin (amorphous surface-treated silica: epoxy Resin) is kneaded at a ratio of 4:6 to prepare a resin mixture for affinity evaluation, and the viscosity at 25° C. of the obtained resin mixture for affinity evaluation is measured using a Brookfield viscometer.
Surface-treated silica with such properties has excellent dielectric properties, excellent dispersibility in resins, and high safety, so it can be used as an inorganic filler for electronic devices that use high-frequency radio waves. It can be used preferably.
The powder tan δ at 1 GHz of the surface-treated silica of the present invention is more preferably 5.0×10 ⁻⁴ or less, still more preferably 2.0×10 ⁻⁴ or less. Although the lower limit of tan δ of the powder at 1 GHz is not particularly limited, it is usually 1.0×10 ⁻⁶ or more.
In addition, the surface-treated silica of the present invention has a powder relative dielectric constant ε at 1 GHz that is more preferably 3.10 or less, and still more preferably 3.00 or less. Although the lower limit of the dielectric constant ε of the powder at 1 GHz is not particularly limited, it is usually 1.0 or more.
The powder tan δ at 10 GHz of the surface-treated silica of the present invention is more preferably 2.0×10 ⁻³ or less, still more preferably 1.5×10 ⁻³ or less. Although the lower limit of tan δ of powder at 10 GHz is not particularly limited, it is usually 1.0×10 ⁻⁶ or more.
In addition, the surface-treated silica of the present invention has a powder dielectric constant ε at 10 GHz, which is more preferably 3.10 or less, and still more preferably 3.00 or less. Although the lower limit of the dielectric constant ε of the powder at 10 GHz is not particularly limited, it is usually 1.0 or more.
The tan δ value and relative dielectric constant ε of the surface-treated silica at 1 GHz and 10 GHz can be measured by the methods described in the examples below.

The viscosity of the resin mixture for affinity evaluation obtained by kneading the surface-treated silica of the first invention and the epoxy resin at a mass ratio of 4:6 at 25° C. should be 75000 mPa s or less, but 70000 mPa s or less. is preferably More preferably, it is 60000 mPa·s or less. Although the lower limit of the viscosity of the resin mixture for affinity evaluation at 25°C is not particularly limited, it is usually 100 mPa·s or more. By using the surface-treated silica having such a viscosity range, the resin composition for electronic materials containing the surface-treated silica of the present invention and a resin also has a preferable viscosity. An electronic material produced using a substance can also be suitably used as an electronic material.
The viscosity of the resin mixture for affinity evaluation at 25° C. can be measured by the method described in Examples below.

The present invention also provides an amorphous surface-treated silica treated with a surface treatment agent, wherein the surface-treated silica has a powder tan δ of 1.0×10 ⁻³ or less at 1 GHz and an ε of 3 .15 or less, tan δ of the powder at 10 GHz is 3.0 × 10 ^-3 or less, and ε is 3.15 or less, and peak A derived from an isolated hydroxyl group in FT-IR measurement forms a hydrogen bond. It is also a surface-treated silica having a peak intensity ratio (A/B) of 0.50 or less to a peak B derived from a hydroxyl group (hereinafter also referred to as the surface-treated silica of the second present invention).
Since such surface-treated silica has excellent dielectric properties and excellent moisture resistance, it can be suitably used as an inorganic filler used in electronic devices that utilize high-frequency radio waves.
The peak intensity ratio (A/B) between the peak A derived from an isolated hydroxyl group and the peak B derived from a hydroxyl group forming a hydrogen bond in the FT-IR measurement of the surface-treated silica is preferably 0.40 or less. . It is more preferably 0.30 or less, and still more preferably 0.20 or less.
Preferred values of tan δ and ε of the powder at 1 GHz and tan δ and ε of the powder at 10 GHz in the surface-treated silica of the second invention are the same as those of the surface-treated silica of the first invention.

The surface-treated silica of the present invention includes the surface-treated silica of the first present invention and the surface-treated silica of the second present invention. is more preferred.

The surface-treating agent used for the surface-treated silica of the present invention is not particularly limited as long as it can improve the dispersibility of silica in the resin. One or more of ring agents, silicone oils, organic phosphates and the like can be used.

The amount of surface treatment with the surface treatment agent in the surface-treated silica of the present invention is not particularly limited, but it is preferably 0.1 to 30% by mass with respect to 100% by mass of silica before surface treatment. More preferably 0.1 to 20% by mass, still more preferably 0.1 to 10% by mass.

The preferred range of the particle diameter, particle size distribution, and BET specific surface area of the surface-treated silica of the present invention is the preferred range of the particle diameter, particle size distribution, and BET specific surface area of the silica contained in the above-described material for producing a filler for electronic materials. Same as range.

3. Electronic material resin composition, electronic material It is also an electronic material.
Since the surface-treated silica of the present invention is excellent in dispersibility in resin, the increase in viscosity and generation of lumps during kneading with resin are sufficiently suppressed. Therefore, when a molded product such as a thin film is produced using the resin composition for electronic materials of the present invention, a molded product with high uniformity and surface smoothness can be obtained.
The proportion of the surface-treated silica of the present invention contained in the resin composition for electronic materials of the present invention is not particularly limited, and may be appropriately selected according to the desired application and properties. is preferably 0.1 to 90% by mass. It is more preferably 1 to 80% by mass, still more preferably 10 to 70% by mass.

The resin contained in the resin composition for electronic materials is not particularly limited, and examples thereof include epoxy resin, polyethylene, polypropylene, polyester, polyamide, polyimide, silicone resin, phenol resin, polysulfone, modified polyphenylene ether resin, polyphenylene sulfide resin, and liquid crystal polymer. , fluororesins, etc., and one or more of these can be used.

The ratio of the resin contained in the resin composition for electronic materials is not particularly limited, and may be appropriately selected according to the desired application and characteristics. % by mass is preferred. It is more preferably 20 to 99% by mass, still more preferably 30 to 90% by mass.

The resin composition for electronic materials may contain a solvent. Although the solvent is not particularly limited, for example, alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; ethers such as dimethyl ether and diethyl ether; , cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, tetramethylbenzene, etc.; aromatic heterocyclic compounds, such as pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone; hexane, pentane, heptane , aliphatic hydrocarbon solvents such as cyclohexane; and glycol ethers such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate. One or more of these can be used.

Although the content of the solvent in the resin composition for electronic materials is not particularly limited, it is preferably 0 to 50% by weight with respect to 100% by weight of the resin composition for electronic materials. More preferably 0 to 40% by mass, still more preferably 0 to 30% by mass.

The resin composition for electronic materials may contain components other than the surface-treated silica, resin, and solvent of the present invention. Other components include fillers, viscosity modifiers, antifoaming agents, and the like. The resin composition for electronic materials may contain one or more other components.

The content of the other components is preferably 30% by mass or less with respect to 100% by mass of the resin composition for electronic materials. More preferably, it is 20% by mass or less, and still more preferably 10% by mass or less.

The resin composition for electronic materials of the present invention preferably has a viscosity at 25° C. of 100000 mPa·s or less. Within such a viscosity range, it becomes easier to form a thin film using the resin for electronic materials of the present invention. The viscosity of the resin composition for electronic materials is more preferably 10000 mPa·s or less, and even more preferably 1000 mPa·s or less.
The viscosity of the resin composition for electronic materials of the present invention can be measured by the same method as the method for measuring the viscosity of the resin mixture for affinity evaluation at 25° C. described in the Examples below.

The electronic material of the present invention is produced using the resin composition for electronic materials of the present invention. In the electronic material of the present invention, the resin composition for electronic materials of the present invention may be molded and used in any manner. It is one of the preferred embodiments of the electronic material of the present invention to include a thin film formed from the resin composition for electronic materials, because a thin film having high surface smoothness can be obtained.

4. Method for Producing Surface-Treated Silica The present invention is also a method for producing surface-treated silica, comprising a step of firing silica obtained by a sol-gel method at 600 to 1200° C., and A step of crushing the fired silica obtained in the crushing step, if necessary, a step of re-firing the crushed fired silica obtained in the crushing step at 700 to 1200 ° C., and a crushed silica obtained in the crushing step. It is also a method for producing surface-treated silica, comprising a step of surface-treating the fired silica or the re-fired silica obtained in the re-fired step with a surface treatment agent.
After firing the silica obtained by the sol-gel method at 600 to 1200 ° C., the fired silica obtained is pulverized and, if necessary, re-fired at 700 to 1200 ° C. to obtain the above-mentioned filler of the electronic material of the present invention. To obtain the surface-treated silica of the present invention by easily obtaining the silica contained in the production material, and surface-treating the pulverized fired silica or re-fired silica thus obtained with a surface treatment agent. can be done.

The step of firing the silica obtained by the sol-gel method at 600 to 1200°C may be performed at 600 to 1200°C, preferably at 700 to 1150°C. More preferably, it is carried out at 800-1100°C.
In addition, the time for holding at high temperature in the firing step is not particularly limited, but it is preferably 10 to 1500 minutes in consideration of sufficient firing of silica and production efficiency. More preferably 10 to 1000 minutes, still more preferably 30 to 500 minutes.

The step of pulverizing the fired silica obtained in the firing step is a step of loosening the aggregates of the primary particles without crushing the primary particles of silica. In the step of firing silica obtained by the sol-gel method at 600 to 1200° C., necking due to sintering between silica particles is likely to occur. By loosening agglomeration of primary particles generated by necking, the particle size of silica can be made uniform and silica with a small variation in particle size distribution can be obtained.

The pyrogenic silica pulverized in the pulverization step preferably has a D50 of 10 μm or less and a D10/D90 of 0.30 or more in a laser diffraction particle size distribution. By pulverizing pyrogenic silica so that D50 and D10/D90 are within such ranges, a composition obtained by blending the surface-treated silica obtained by the method for producing surface-treated silica of the present invention with a resin is obtained. The suitability for thinning becomes more excellent, and a molded article formed using the composition has higher surface flatness.
D50 of the silica is more preferably 5 μm or less, and still more preferably 2 μm or less. Although the lower limit of D50 of silica is not particularly limited, it is usually 0.005 μm or more.
The D10/D90 of the silica is more preferably 0.40 or more, still more preferably 0.60 or more, particularly preferably 0.70 or more, and most preferably 0.75 or more. is.

Further, the fired silica pulverized in the pulverization step preferably has a maximum volume frequency of 30% or more in a laser diffraction particle size distribution. By using such silica, the molded article formed using the composition obtained by blending the surface-treated silica obtained by the method for producing surface-treated silica of the present invention with a resin has a higher surface flatness. Therefore, it contributes to improving the performance of molded products and electronic materials.
The maximum volume frequency of the silica is more preferably 40% or more, still more preferably 45% or more.

The fired silica crushed in the above crushing process is obtained by analyzing a total of 100 or more particles in two or more different fields of view in SEM observation using image analysis software Azokun (manufactured by Asahi Kasei Engineering Co., Ltd.). In addition, among the maximum possible diameter (maximum diameter) d of each particle, the ratio (dmax/d50) between the maximum particle diameter dmax and the average particle diameter d50 is preferably 5.0 or less.
By using calcined silica with a dmax/d50 of 5.0 or less, obtained using a more accurate average particle size (average primary particle size) d50 of calcined silica particles excluding aggregated particles obtained by SEM observation, The molded article formed using the composition obtained by blending the surface-treated silica obtained by the method for producing the surface-treated silica of the present invention with a resin has a higher surface flatness, and as a result, the dielectric properties are more uniform. and contributes to improving the performance of electronic materials.
dmax/d50 is more preferably 2.5 or less, and still more preferably 1.8 or less. Although the lower limit of dmax/d50 is not particularly limited, it is usually 1.01 or more.
The average particle diameter d50 obtained from the SEM image is the average value of the particle diameters of 100 or more silica particles automatically extracted from the SEM image by image analysis software.
A method for determining the maximum particle size dmax and the average particle size d50 of silica from SEM observation is as described in Examples below.

The fired silica pulverized in the pulverization step preferably has a BET specific surface area of 0.5 m ² /g or more. With such a specific surface area, the average particle size is relatively small, so it is suitable for thin film applications. The BET specific surface area of the fired silica pulverized in the pulverization step is more preferably 1 m ² /g or more, and still more preferably 2 m ² /g or more. Although the upper limit of the BET specific surface area of silica is not particularly limited, it is usually 300 m ² /g or less.

In the method for producing surface-treated silica of the present invention, if necessary, the step of re-firing the pulverized pyrogenic silica obtained in the pulverizing step at 700 to 1200°C is performed.
As described above, by loosening agglomeration of primary particles generated by necking that occurs in the firing process in the crushing process, the particle size of silica can be made uniform and silica with a small variation in particle size distribution can be obtained. On the other hand, however, pulverization generates a new interface, and the new interface becomes a factor of variation in the amount of hydroxyl groups on the silica surface. Therefore, in the method for producing surface-treated silica of the present invention, if necessary, the silica after crushing is re-fired in order to control the amount of hydroxyl groups on the surface of the silica after crushing. By performing re-firing to produce silica, the obtained silica can be made more excellent in dielectric properties.
The method of pulverizing the fired silica obtained in the firing step is not particularly limited as long as the primary particles can be loosened without crushing the primary particles of silica, but it can be performed with an air flow pulverizer or the like.

When the pulverized fired silica is refired at 700 to 1200° C., the necking that occurs in the first firing hardly occurs. Both the particle size distribution and the amount of hydroxyl groups on the silica surface can be controlled by such a series of steps of calcination, pulverization, and re-calcination.
The re-baking process may be performed at 700 to 1200°C, preferably at 800 to 1200°C. It is more preferably carried out at 800 to 1150°C, still more preferably at 850 to 1100°C.
The holding time at high temperature during the re-baking step is not particularly limited, but it is preferably 10 to 1500 minutes in consideration of sufficient baking of silica and production efficiency. More preferably 10 to 1000 minutes, still more preferably 30 to 500 minutes.

In the method for producing surface-treated silica of the present invention, when both the step of calcining silica and the step of recalcining are performed, the difference between the calcining temperature and the recalcining temperature is preferably 50° C. or more. By providing such a temperature difference, the desired silica can be obtained without applying excessive heat. More preferably, the difference between the sintering temperature and the re-sintering temperature is 100° C. or more. More preferably, it is 150° C. or higher. Moreover, the difference between the firing temperature and the re-firing temperature is usually 600° C. or less.

In addition, when producing silica with few isolated hydroxyl groups in which most of the isolated hydroxyl groups on the surface are consumed by the reaction with the surface treatment agent, the step of firing or the step of re-firing can be performed at 1050 to 1200 ° C. preferable. Firing or re-firing at such a temperature reduces the number of isolated hydroxyl groups on the surface, resulting in silica in which most of the isolated hydroxyl groups on the surface are consumed by the reaction with the surface treatment agent. Firing at 1050 to 1200°C may be performed in the step of firing or may be performed in the step of refiring, but it is preferable to perform the step of refiring at 1050 to 1200°C.

The step of firing the silica obtained by the sol-gel method and the step of re-firing the pulverized fired silica are preferably carried out in a low humidity atmosphere. By firing in a low-humidity atmosphere, the resulting surface-treated silica has a lower dielectric loss tangent and excellent dielectric properties.
As the low-humidity atmosphere, an atmosphere with a humidity of 90% or less at 30° C. before starting the temperature rise is preferable. More preferably, it is an atmosphere with a humidity of 70% or less at 30°C, and even more preferably an atmosphere with a humidity of 60% or less at 30°C.

The atmosphere in which the step of firing the silica obtained by the sol-gel method and the step of re-firing the pulverized fired silica are not particularly limited except for a low humidity atmosphere. , an atmosphere of an inert gas such as argon, or the like.

After the crushing step or the step of recalcining the crushed fired silica, and before the step of surface-treating the crushed fired silica or recalcined silica obtained in the crushing step with a surface treatment agent, It is preferable to perform a step of cooling the pulverized fired silica or re-fired silica obtained in the pulverizing step. After cooling, the crushed fired silica or refired silica obtained in the crushing step is subjected to a surface treatment with a surface treatment agent, so that the crushed fired silica or refired silica obtained in the crushing step is processed. and the surface treatment agent can be sufficiently reacted.
In the step of cooling the crushed fired silica or recalcined silica obtained in the crushing step, the crushed fired silica or recalcined silica obtained in the crushing step is preferably cooled to about room temperature, It is preferable to cool the pulverized fired silica or re-fired silica obtained in the pulverizing step at room temperature for 5 to 1000 minutes.

In the method for producing surface-treated silica of the present invention, until the step of surface-treating the crushed fired silica obtained in the crushing step or the refired silica obtained in the refired step with a surface treatment agent, It is preferable not to expose it to a humid environment. When the crushed pyrogenic silica or recalcined silica obtained in the crushing process comes into contact with a high-humidity environment, isolated hydroxyl groups are generated on the surface of the crushed pyrogenic silica or recalcined silica obtained in the crushing process. , the dielectric loss tangent of the surface-treated silica obtained by performing the surface treatment process may increase. Therefore, in the method for producing surface-treated silica of the present invention, the step of surface-treating the crushed fired silica obtained in the crushing step or the refired silica obtained in the refired step with a surface treatment agent It is preferable to keep the calcined silica in an environment with a humidity of 90% or less at 30°C. More preferably, it is kept in an environment with a humidity of 70% or less at 30°C, and more preferably in an environment with a humidity of 25% or less at 30°C.
It should be noted that "surface treatment of the crushed calcined silica obtained in the crushing step or the recalcined silica obtained in the recalcining process with a surface treatment agent" here refers to the surface treatment of the crushed silica obtained in the crushing step. If the crushed fired silica is not re-fired, the crushed fired silica obtained in the crushing step is surface-treated with a surface treatment agent, and if re-fired, the re-fired silica obtained by the re-burning step. It means to surface-treat the refired silica with a surface-treating agent.

The proportion of the surface treatment agent used in the surface treatment step is not particularly limited as long as the silica can be surface treated, but the crushed fired silica obtained in the crushing step or the refired silica obtained in the refired step It is preferably 0.1 to 30% by mass with respect to 100% by mass of silica. By using the surface treatment agent in such a ratio, the silica surface can be sufficiently treated and moisture absorption can be prevented. The proportion of the surface treatment agent is more preferably 0.1 to 20% by mass with respect to 100% by mass of the pulverized fired silica or refired silica obtained in the pulverizing step, and more preferably pulverized It is 0.1 to 10% by mass with respect to 100% by mass of pulverized fired silica or refired silica obtained in the process.
As the surface treatment agent used in the surface treatment step, the same agents as those described above can be used.

In the surface treatment step, the crushed fired silica or refired silica obtained in the crushing step is sufficiently surface-treated with a surface treatment agent. After mixing the pyrogenic silica and the surface treatment agent, it is preferable to heat the mixture to bake the surface treatment agent onto the silica. The heating temperature for the baking treatment may be appropriately set according to the type of the surface treatment agent and the like, but is preferably 30 to 500°C. It is more preferably 50 to 300°C, still more preferably 80 to 250°C.
Moreover, the heating time for the baking treatment is preferably 10 to 600 minutes. More preferably 30 to 400 minutes, still more preferably 60 to 300 minutes.

The method for producing surface-treated silica of the present invention may include other steps than the steps described above. Other processes include a dispersion treatment process, a sieving process, a pressurization process, and a crushing process.

Specific examples are given below to describe the present invention in detail, but the present invention is not limited only to these examples. Unless otherwise specified, "%" and "wt%" mean "% by weight (% by mass)". In addition, the measuring method of each physical property is as follows.
<FT-IR measurement>
Thermo Fisher Scientific K.K. K. A diffuse reflection application was attached to NICOLET 4700 manufactured by Manufacture, and the sample was provided to the measurement ^jig so that the powder was smooth.
Peaks of the obtained data were detected using analysis software OMNIC.
Detection of isolated hydroxyl group A: Peak detection was performed after performing auto-baseline correction with an analysis range of 3800 to 3500 cm ⁻¹ by OMNIC. In peak detection, the threshold value was set to 0.01 for separation from noise, and peaks existing around 3800 to 3700 cm ⁻¹ were detected. The highest peak intensity was adopted among the peaks.
Detection of hydrogen-bonded hydroxyl group B: Peak detection was performed after performing auto-baseline correction with an analysis range of 3800 to 3500 cm ⁻¹ by OMNIC. In peak detection, the threshold value was set to 0.01 for separation from noise, and peaks existing around 3700 to 3600 cm ⁻¹ were detected. The highest peak intensity was adopted among the peaks.
Detection of adsorbed water: Peak detection was performed after performing auto-baseline correction with an analysis range of 3500 to 3000 cm ⁻¹ by OMNIC. In peak detection, the threshold value was set to 0.01 for separation from noise, and the highest peak intensity was adopted among the peaks. Determination of the presence or absence of adsorbed water in the examples means that no peak is detected under the conditions.
In both cases, if the detection sensitivity is too high, all noise is detected as a peak, so the sensitivity was adjusted to 5.

<Average particle size and particle size distribution measurement by laser diffraction particle size distribution measurement>
The silica powder before the surface treatment was measured for particle size distribution with LA-950 manufactured by Horiba, Ltd. A small amount of powder was added to a 0.05% by weight sodium hexametaphosphate aqueous solution, dispersed with an ultrasonic homogenizer as a pretreatment, and subjected to a measurement device. The measurement was performed with the refractive index of silica powder n=1.460 and the refractive index of water n=1.333.
<XRD measurement>
The silica powder before the surface treatment was measured with an X-ray diffraction measurement device RINT-TTRIII manufactured by Rigaku Corporation. The measurement range was 2θ: 20 to 60°, the step width was 0.02°, the counting time was 0.5 s, the voltage was 50 V, and the current was 300 mA. The measurement results were analyzed with analysis software PDXL, and when a peak was detected at 20 to 30° on the software, it was determined that there was crystallinity. A peak search was automatically performed according to the analysis template, and the σ cut value was set to 3.0.
<BET specific surface area>
After degassing with a degassing device at a N ² flow rate of 50 mL/min at 200° C. for 20 min, the specific surface area was measured by the BET 1-point method using Macsorb HM-1220 manufactured by Mountech.

<Moisture absorption rate>
10.0 g of the surface-treated silica obtained in Examples and Comparative Examples was placed in a glass petri dish previously dried at 105 ° C. for 2 hours, placed in a constant temperature and humidity bath at a temperature of 85 ° C. and a humidity of 85% RH. It was taken out after a period of time, and the change in mass of the surface-treated silica before and after the addition was measured.
Moisture absorption rate (%) = {(ba)/a} x 100
a: Mass (g) of surface-treated silica before being put into the constant temperature and humidity chamber
b: mass (g) of the surface-treated silica 264 hours after being placed in the constant temperature and humidity chamber
<Increase rate of dielectric properties and dielectric loss tangent>
The dielectric constant ε and the dielectric loss tangent tan δ of the powder at a predetermined frequency were measured using a dielectric constant measuring device manufactured by AET Co., Ltd. using the cavity resonator perturbation method.
In addition, the dielectric constant ε and the dielectric loss tangent tan δ at 10 GHz of the surface-treated silica after the moisture absorption measurement were measured, and the change in the dielectric loss tangent of the powder before and after the moisture absorption was measured.
Increase rate of dielectric loss tangent (%) = {(tan δ5 - tan δ4) / tan δ4} × 100
tan δ4: dielectric loss tangent of surface-treated silica tan δ5: dielectric loss tangent of surface-treated silica 264 hours after being placed in a constant temperature and humidity chamber <500°C to 1000°C desorbed water content>
Using a temperature-programmed desorption spectrometer (Electron Science EMD-WA1000S/W; TDS), the temperature of the upper thermocouple is increased from 25 ° C. to 1000 ° C. at a rate of 30 ° C./min in an air atmosphere. From the area value in the range of 500° C. to 1000° C. of the obtained mass chromatogram (m/z=18), the number of molecules desorbed from H ₂ O was calculated. A carbon sheet, a sample powder (10 mg), and a carbon sheet were placed in this order on a quartz sample plate, and the measurement was performed.

<SEM image observation>
The silica particles were placed on a sample table and observed with a scanning electron microscope JSM-7000f manufactured by JEOL Ltd. to obtain an SEM image.
<Measurement of maximum particle size dmax and average particle size d50 of silica from images obtained by SEM image observation>
The obtained SEM image was analyzed using the image analysis software Azo-kun manufactured by Asahi Kasei Engineering Co., Ltd. The maximum possible diameter d for each of 100 or more particles was randomly analyzed, and the maximum particle diameter dmax and average particle diameter d50 were calculated from the obtained analysis results, and dmax/d50 was calculated.

<Method for preparing resin mixture for affinity evaluation>
30.00 g of the surface-treated silica obtained in Examples and Comparative Examples and 45.00 g of an epoxy resin (EPICLON 850 manufactured by DIC Corporation, viscosity at 25° C. of 11000 to 15000 mPa s) were kneaded to prepare a resin mixture for affinity evaluation. made.
<Viscosity measurement>
With respect to the obtained resin mixture for affinity evaluation, the viscosity of the resin mixture for affinity evaluation at 25° C. was measured using a Brookfield viscometer model BM manufactured by Tokyo Keiki Co., Ltd.
<Evaluation of affinity with resin>
2.00 g of the obtained resin mixture for affinity evaluation was sandwiched between glass plates of 100 mm×100 mm together with a spacer of 0.18 mm thickness so that the thickness would be uniform to prepare a test sample. The appearance of the resulting test sample was visually confirmed within 15 minutes. When the number of lumps that can be visually counted is 0 to 20, "○", when 21 to 50, "△", and when 51 or more, "×", the affinity between the surface-treated silica and the resin. evaluated.

EXAMPLES In the examples, it was used as raw material silica synthesized by the sol-gel method.
The deliverable of the example is silica, which is scheduled to be sold after September 2021 under the trade name of Sciqas-LT by the present applicant.

Example 1
Raw material silica synthesized by the sol-gel method was filled in a sagger made of mullite cordierite and placed in a firing furnace. The temperature of the firing furnace was increased at 100°C/h, and the temperature increase was stopped when the temperature reached 1000°C. After sintering at 1000° C. for 5 hours, the temperature was lowered to room temperature at 100° C./h to collect the sintered powder, followed by dry pulverization with an airflow pulverizer.
The calcined silica after pulverization was filled in a sagger made of mullite cordierite and placed in a calcining furnace. The temperature of the firing furnace was increased at 100°C/h, and the temperature increase was stopped when the temperature reached 800°C. After firing at 800° C. for 5 hours, the temperature was lowered to room temperature at a rate of 100° C./h, and a re-fired silica 1 was obtained.
FT-IR measurement of the obtained refired silica 1 was performed, and peak A derived from isolated hydroxyl groups appearing at 3800 to 3700 cm ^-1 and peak B derived from hydroxyl groups forming hydrogen bonds appearing at 3700 to 3600 cm ^-1 . and the presence or absence of a peak derived from adsorbed water at 3500 to 3100 cm ⁻¹ , and the dielectric constant ε and dielectric loss tangent tan δ at 1 GHz and 10 GHz were measured. Moreover, XRD measurement and BET specific surface area measurement were performed. These results are shown in Table 1. FIG. 1 shows the FT-IR measurement results of the refired silica 1.

50.00 g of the resulting recalcined silica 1 was placed in a plastic bag, and 0.35 g of a surface treatment agent (hexamethyldisilazane (HMDS) equivalent to 0.7% by mass with respect to the recalcined silica 1: Shin-Etsu Chemical Co., Ltd. SZ-31) manufactured by Co., Ltd. was added to the recalcined silica 1 in a sprinkling manner. After sealing the plastic bag and mixing the contents of the bag well, take out the contents of the plastic bag into a stainless steel vat, place it in a dryer, and bake the surface treatment agent at 150°C for 3 hours to treat the surface. The steps were carried out to obtain surface-treated silica 1.
Regarding the obtained surface-treated silica 1, D10, D50, D90, maximum volume frequency, D10/D90 measurement, FT-IR measurement, peak A derived from an isolated hydroxyl group appearing at 3800 to 3700 cm ^-1 and 3700 to 3600 cm ^- Measurement of peak intensity ratio (A/B) with peak B derived from hydroxyl groups forming hydrogen bonds appearing in ¹ , measurement of relative permittivity ε and dielectric loss tangent tan δ at 1 GHz and 10 GHz, and SEM image observation I made a measurement. In addition, the amount of desorbed water at 500° C. to 1000° C. was measured, the moisture absorption was measured, and the dielectric loss tangent tan δ at 10 GHz after the measurement of the moisture absorption and its rate of increase were measured. A lower increase rate of the dielectric loss tangent indicates that the change in the dielectric loss tangent over time is suppressed. The lower the value, the more preferably 200% or less, more preferably 150% or less, and even more preferably 100% or less.
Furthermore, 30.00 g of surface-treated silica 1 and 45.00 g of epoxy resin (manufactured by DIC Corporation, EPICLON 850) were kneaded to prepare a resin mixture for evaluating the affinity of the surface-treated silica with the resin. , viscosity measurement and affinity evaluation with resin (dispersibility evaluation of surface-treated silica 1) were performed. These results are shown in Table 2.

Examples 2 and 3
Refired silicas 2 and 3 were obtained in the same manner as in Example 1 except that the refired temperature in the refired step was changed as shown in Table 1, and these were surface-treated to obtain surface-treated silicas 2 and 3.
Various measurements similar to those in Example 1 were performed on the obtained refired silicas 2 and 3 and surface-treated silicas 2 and 3. Tables 1 and 2 show the results. FT-IR measurement results of refired silica 2 are shown in FIG.

Example 4
Recalcined silica 4 was obtained in the same manner as in Example 1 except that an average particle diameter different from that in Example 1 was used as the raw material silica, and the ratio of HMDS used to the recalcined silica was changed. After treatment, surface-treated silica 4 was obtained.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 4 and surface-treated silica 4 . Tables 1 and 2 show the results.

Example 5
Recycling was carried out in the same manner as in Example 1, except that an average particle size different from that of Example 1 was used as the raw material silica, the firing and recalcination temperatures were changed, and the ratio of HMDS used to the recalcined silica was changed. A pyrogenic silica 5 was obtained and surface-treated to obtain a surface-treated silica 5.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 5 and surface-treated silica 5 . Tables 1 and 2 show the results.

Example 6
A recalcined silica 6 was obtained in the same manner as in Example 1.
50.00 g of the obtained recalcined silica 6 was weighed and put into a dry mixer. 0.50 g of a surface treatment agent (phenyltrimethoxysilane (PTMS): KBM-103 manufactured by Shin-Etsu Chemical Co., Ltd.) corresponding to 1.0% by mass with respect to the refired silica 6 was added to the dry mixer and mixed. .
After that, the mixed powder was taken out from the dry mixer, put into a dryer, and baked with a surface treatment agent at 150° C. for 3 hours to carry out a surface treatment step, whereby surface-treated silica 6 was obtained.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 6 and surface-treated silica 6 . Tables 1 and 2 show the results.

Example 7
Using vinyltrimethoxysilane (VTMS: KBM-1003 manufactured by Shin-Etsu Chemical Co., Ltd.) instead of phenyltrimethoxysilane as a surface treatment agent, using a surface treatment agent equivalent to 0.7% by mass with respect to the refired silica, Refired silica 7 was obtained in the same manner as in Example 6 except that the surface treatment was performed under the baking treatment conditions of the surface treatment agent at 130° C. for 3 hours, and the surface treated silica 7 was obtained by surface treatment.
Various measurements similar to those in Example 6 were performed on the obtained refired silica 7 and surface-treated silica 7 . Tables 1 and 2 show the results.

Examples 8 and 9
Re-fired silicas 8 and 9 were obtained in the same manner as in Example 1 except that the re-fired temperature in the re-fired step was changed, and these were surface-treated to obtain surface-treated silicas 8 and 9.
Various measurements similar to those in Example 1 were performed on the obtained refired silicas 8 and 9 and surface-treated silicas 8 and 9. Tables 1 and 2 show the results.

Example 10
Refired silica 10 was obtained in the same manner as in Example 1, except that an average particle diameter different from that of Example 1 was used as raw material silica, and the refired temperature and the ratio of HMDS used to the refired silica were changed. , and surface-treated them to obtain surface-treated silica 10.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 10 and surface-treated silica 10 . Tables 1 and 2 show the results.

Example 11
Recalcined silica 11 was prepared in the same manner as in Example 1, except that an average particle size different from that in Example 1 was used as the raw material silica, and the recalcination temperature and time, and the ratio of HMDS used to the recalcined silica were changed. and surface-treated them to obtain surface-treated silica 11.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 11 and surface-treated silica 11 . Tables 1 and 2 show the results.

Example 12
The same as in Example 1, except that the starting silica used had an average particle size different from that of Example 1, the firing temperature was changed, re-firing was not performed, and the ratio of HMDS used to the starting silica was changed. Then, the refired silica 12 was obtained, and the surface treated silica 12 was obtained by surface treatment.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 12 and surface-treated silica 12 . Tables 1 and 2 show the results.

Example 13
The same as in Example 1, except that an average particle diameter different from that in Example 1 was used as the raw material silica, the firing temperature was changed, and the re-firing temperature and time, and the ratio of HMDS used to the re-firing silica were changed. Then, the refired silica 13 was obtained and surface-treated to obtain the surface-treated silica 13.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 13 and surface-treated silica 13 . Tables 1 and 2 show the results.

Example 14
Refired silica 14 was obtained in the same manner as in Example 1, except that the average particle size of the raw material silica was different from that of Example 1, and the refired temperature and the ratio of HMDS used to the refired silica were changed. , and surface-treated them to obtain surface-treated silica 14.
Various measurements similar to those in Example 1 were performed on the obtained refired silica 14 and surface-treated silica 14 . Tables 1 and 2 show the results.

Comparative Examples 1 and 2
Comparative recalcined silica 1 and comparative calcined silica 2 were prepared in the same manner as in Example 1 except that the calcining temperature in the recalcining step was changed to 1300 ° C. (Comparative Example 1) or the recalcining step was not performed (Comparative Example 2). These were surface-treated to obtain comparative surface-treated silicas 1 and 2.
Various measurements similar to those in Example 1 were performed on the comparative refired silica 1, the comparative fired silica 2, and the comparative surface-treated silicas 1 and 2 thus obtained. Tables 1 and 2 show the results. In addition, the FT-IR measurement results of comparative recalcined silica 1 and comparative calcined silica 2 are shown in FIGS. FIG. 5 shows the displayed results.

Comparative Examples 3 and 4
Competitor's product A (Comparative Example 3) and Competitor's product B (Comparative Example 4) were used as calcined and crushed products of raw material silica, which correspond to the raw material silica subjected to calcining and crushing processes, and recalcined silica Comparative refired silicas 3 and 4 were obtained in the same manner as in Example 1 except that the proportion of HMDS used was changed (Comparative Example 3), and these were surface-treated to obtain comparative surface-treated silicas 3 and 4. rice field.
Various measurements similar to those in Example 1 were performed on the obtained comparative refired silicas 3 and 4 and comparative surface-treated silicas 3 and 4. Tables 1 and 2 show the results.
Competitor A is crystalline silica having an average particle size of 0.5 μm produced by a dry method.
Competitor B is an amorphous silica produced by the sol-gel method, but peak A derived from an isolated hydroxyl group appearing at 3800 to 3700 cm ⁻¹ in FT-IR measurement is not observed.

Comparative example 5
Same as Example 1, except that a different average particle diameter from that of Example 1 was used as raw material silica, the firing temperature in the re-firing step was changed to 400° C., and the ratio of HMDS used to the re-firing silica was changed. Comparative refired silica 5 was obtained in the same manner and surface treated to obtain comparative surface treated silica 5.
Various measurements similar to those in Example 1 were performed on the comparative refired silica 5 and the comparative surface-treated silica 5 thus obtained. Tables 1 and 2 show the results.

Comparative example 6
Same as Example 1, except that an average particle size different from that of Example 1 was used as the raw material silica, the firing temperature in the re-firing step was changed to 600°C, and the ratio of HMDS used to the re-firing silica was changed. Comparative refired silica 6 was obtained in the same manner and surface treated to obtain comparative surface treated silica 6.
Various measurements similar to those in Example 1 were performed on the comparative refired silica 6 and the comparative surface-treated silica 6 thus obtained. Tables 1 and 2 show the results.

From the comparison of Examples 1 to 14 and Comparative Examples 1 to 6, the peak intensity ratio (A / B) between the peak A derived from an isolated hydroxyl group and the peak B derived from a hydroxyl group forming a hydrogen bond in the FT-IR measurement. is 1.0 to 75, and there is substantially no peak derived from adsorbed water at 3500 to 3100 cm ^-1 , and the dielectric loss tangent tan δ per unit specific surface area is low. Surface treatment using amorphous silica as a raw material By doing, it was confirmed that amorphous surface-treated silica excellent in dielectric properties, uniform dispersibility in resin, and viscosity suppression can be obtained.
In addition, the surface-treated silica of Examples 10 to 14 having a peak intensity ratio (A/B) of 0.50 or less has a lower hygroscopicity and a small change in dielectric properties after being placed in a hygroscopic environment. confirmed.

Claims

The peak intensity ratio (A/B) between the peak A derived from an isolated hydroxyl group and the peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement is 1.0 to 75.0, and 3500 to A material for producing a filler for an electronic material containing amorphous silica having substantially no peak derived from adsorbed water at 3100 cm −1 .
2. The material for producing a filler for an electronic material according to claim 1, wherein the silica has a D50 of 10 μm or less and a D10/D90 of 0.30 or more in a laser diffraction particle size distribution.
3. The silica according to claim 1 or 2, wherein the ratio of tan δ of the powder to the BET specific surface area (tan δ/BET specific surface area) at 1 GHz and 10 GHz is 1.0 × 10 -3 or less. Materials for making fillers for electronic materials.
The silica has a peak intensity ratio (A/B) of 1.0 to 10.0 between a peak A derived from an isolated hydroxyl group and a peak B derived from a hydroxyl group forming a hydrogen bond in FT-IR measurement. The material for producing a filler for an electronic material according to any one of claims 1 to 3, characterized by:
Amorphous surface-treated silica treated with a surface treatment agent,
The surface-treated silica has a powder tan δ of 1.0×10 −3 or less and ε of 3.15 or less at 1 GHz,
Powder tan δ at 10 GHz is 3.0 × 10 -3 or less, ε is 3.15 or less, and viscosity at 25 ° C. measured under the following conditions is 75000 mPa s or less. Crystalline surface-treated silica.
(conditions)
Using the amorphous surface-treated silica and an epoxy resin having a viscosity of 11000 to 15000 mPa s at 25 ° C., the mass ratio of the amorphous surface-treated silica to the epoxy resin (amorphous surface-treated silica: epoxy Resin) is kneaded at a ratio of 4:6 to prepare a resin mixture for affinity evaluation, and the viscosity at 25° C. of the obtained resin mixture for affinity evaluation is measured using a Brookfield viscometer.
Amorphous surface-treated silica treated with a surface treatment agent,
The surface-treated silica has a powder tan δ of 1.0×10 −3 or less and ε of 3.15 or less at 1 GHz,
The tan δ of the powder at 10 GHz is 3.0 × 10 -3 or less, and the ε is 3.15 or less, and the peak A derived from the isolated hydroxyl group in the FT-IR measurement and the hydroxyl group-derived hydroxyl group forming a hydrogen bond A surface-treated silica having a peak intensity ratio (A/B) to peak B of 0.50 or less.
A resin composition for electronic materials, comprising the surface-treated silica according to claim 5 or 6 and a resin.
An electronic material produced using the resin composition for an electronic material according to claim 7 .
A method for producing surface-treated silica, comprising:
The production method includes a step of firing amorphous silica obtained by a sol-gel method at 600 to 1200 ° C.
a step of pulverizing the fired silica obtained in the firing step;
If necessary, a step of re-firing the pulverized fired silica obtained in the pulverizing step at 700 to 1200 ° C., and
A method for producing surface-treated silica, comprising a step of surface-treating the crushed fired silica obtained in the crushing step or the refired silica obtained in the refired step with a surface treatment agent.