JP2023084801A - Fullerene coating silica particles, and manufacturing method and application thereof - Google Patents

Fullerene coating silica particles, and manufacturing method and application thereof Download PDF

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JP2023084801A
JP2023084801A JP2021199100A JP2021199100A JP2023084801A JP 2023084801 A JP2023084801 A JP 2023084801A JP 2021199100 A JP2021199100 A JP 2021199100A JP 2021199100 A JP2021199100 A JP 2021199100A JP 2023084801 A JP2023084801 A JP 2023084801A
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fullerene
silica particles
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resin
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亘章 加治
Nobuaki Kaji
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Resonac Holdings Corp
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Abstract

To provide silica particles capable of obtaining a resin-cured product whose dielectric breakdown voltage is improved.SOLUTION: A resin composition containing silica particles each whose surface is coated with fullerene is prepared and cured to obtain a resin-cured product whose dielectric breakdown voltage is improved. A manufacturing method of silica particles each whose surface is coated with fullerene comprises a step of controlling a coating amount of fullerene onto a surface of each of the silica particles while pulverizing raw material silica particles, by applying mechanical shear to the raw material silica particles in a solution in which fullerene is dissolved.SELECTED DRAWING: Figure 2

Description

本発明は、フラーレン被覆シリカ粒子及びその製造方法、並びに、樹脂組成物、樹脂硬化物及び電気絶縁材料など前記シリカ粒子の用途に関する。 TECHNICAL FIELD The present invention relates to fullerene-coated silica particles, a method for producing the same, and uses of the silica particles such as resin compositions, cured resins, and electrical insulating materials.

固体絶縁スイッチギヤの絶縁体として、高い絶縁性を持たせるために充填剤を添加したエポキシ樹脂硬化物が使われている。例えば、特許文献1では、修飾された層状シリケート化合物等のナノ粒子と、シリカ等のマイクロ粒子が分散されているエポキシ系注型樹脂により、少なくとも主回路部が絶縁されているスイッチギヤが開示されている。 Cured epoxy resins with filler added are used as insulators for solid insulated switchgears to provide high insulation. For example, Patent Literature 1 discloses a switchgear in which at least the main circuit portion is insulated by an epoxy-based casting resin in which nanoparticles such as a modified layered silicate compound and microparticles such as silica are dispersed. ing.

また、充填剤の凝集は絶縁性を損ねるので、それを回避するためにシランカップリング剤が一般的に使われている(例えば、特許文献2)。 In addition, silane coupling agents are generally used to avoid the aggregation of fillers, which impairs insulation (for example, Patent Document 2).

上記とは異なる絶縁破壊電圧を向上させる方法として、エポキシ樹脂へのフラーレンの添加が行われている。例えば、特許文献3では、絶縁破壊電圧が高く、かつ低粘度のエポキシ樹脂組成物として、エポキシ樹脂中にフラーレンが分散し、前記フラーレンの含有量が0.1~3質量%である樹脂組成物が開示されている。 As a method for improving the dielectric breakdown voltage different from the above, fullerene is added to the epoxy resin. For example, in Patent Document 3, as an epoxy resin composition having a high dielectric breakdown voltage and a low viscosity, fullerene is dispersed in an epoxy resin, and the content of the fullerene is 0.1 to 3% by mass. is disclosed.

特開2010-93956号公報JP 2010-93956 A 特開2012-158622号公報JP 2012-158622 A 特開2018-177895号公報JP 2018-177895 A

前述したように充填剤を分散させることは絶縁破壊電圧の向上に寄与するが、分散のために用いられるシランカップリング剤は、後述する実施例・比較例で示したように、得られる樹脂硬化物の絶縁破壊電圧向上の観点からは不利に働くこともある。 As described above, dispersing the filler contributes to the improvement of the dielectric breakdown voltage, but the silane coupling agent used for dispersion, as shown in the examples and comparative examples described later, is used to cure the resulting resin. It may work disadvantageously from the viewpoint of improving the dielectric breakdown voltage of the object.

本発明はこのような欠点を解消し、より絶縁破壊電圧の向上した樹脂硬化物を得ることができるシリカ粒子を提供することにある。 An object of the present invention is to eliminate such drawbacks and to provide silica particles from which a cured resin product having an improved dielectric breakdown voltage can be obtained.

本発明は、上記課題を解決するため、以下の手段を提供する。
[1] 表面がフラーレンで被覆されているシリカ粒子。
[2] 前記フラーレンはシリカ粒子表面に化学吸着している前項[1]に記載のシリカ粒子。
[3] 前記フラーレンはC60が質量比で最も多く含まれる前項[1]または[2]に記載のシリカ粒子。
[4] 前記シリカ粒子の表面積当たりのフラーレンの被覆量が0.02~1.60mg/mである前項[1]~[3]のいずれかに記載のシリカ粒子。
[5] 前項[1]~[4]のいずれかに記載のシリカ粒子と硬化性樹脂とを含む樹脂組成物。
[6] 前項[5]に記載の樹脂組成物を硬化させた樹脂硬化物。
[7] 前項[6]に記載の樹脂硬化物からなる電気絶縁材料。
[8] フラーレンが溶解している溶液中で原料シリカ粒子に機械的シェアをかける工程を有する前項[1]~[4]のいずれかに記載のシリカ粒子の製造方法。
[9] 前記機械的シェアをかける工程が、原料シリカ粒子を解砕することにより行われる前項[8]に記載のシリカ粒子の製造方法。
In order to solve the above problems, the present invention provides the following means.
[1] Silica particles whose surfaces are coated with fullerenes.
[2] The silica particles according to [1] above, wherein the fullerene is chemically adsorbed on the silica particle surface.
[3] The silica particles according to the above item [1] or [2], wherein the fullerene contains C60 at the highest mass ratio.
[4] The silica particles according to any one of [1] to [3] above, wherein the amount of fullerene coating per surface area of the silica particles is 0.02 to 1.60 mg/m 2 .
[5] A resin composition comprising the silica particles according to any one of [1] to [4] above and a curable resin.
[6] A cured resin obtained by curing the resin composition according to [5] above.
[7] An electrical insulating material comprising the cured resin of [6] above.
[8] The method for producing silica particles according to any one of [1] to [4] above, which comprises a step of applying mechanical shear to the starting silica particles in a solution in which fullerene is dissolved.
[9] The method for producing silica particles according to [8] above, wherein the step of applying mechanical shear is performed by pulverizing raw material silica particles.

本発明のフラーレン被覆シリカ粒子を用いることにより、絶縁破壊電圧の高い樹脂硬化物が提供される。 By using the fullerene-coated silica particles of the present invention, a cured resin having a high dielectric breakdown voltage is provided.

図1は、実施例2~5及び比較例2における、フラーレン被覆シリカ粒子のフラーレン被覆量と樹脂組成物の粘度との関係を示す図である。FIG. 1 is a diagram showing the relationship between the fullerene coating amount of fullerene-coated silica particles and the viscosity of a resin composition in Examples 2 to 5 and Comparative Example 2. FIG. 図2は、実施例2~5及び比較例2における、フラーレン被覆シリカ粒子のフラーレン被覆量と樹脂硬化物の絶縁破壊電圧との関係を示す図である。FIG. 2 is a diagram showing the relationship between the fullerene coating amount of fullerene-coated silica particles and the dielectric breakdown voltage of a cured resin in Examples 2 to 5 and Comparative Example 2. FIG.

以下、本発明の実施形態について詳細に説明する。なお、以下に示す実施形態は、発明の趣旨をより良く理解させるために具体的に説明するものであり、特に指定のない限り、本発明を限定するものではない。 BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. It should be noted that the embodiments shown below are specifically described for better understanding of the gist of the invention, and do not limit the invention unless otherwise specified.

(フラーレン被覆シリカ粒子)
本実施形態のフラーレン被覆シリカ粒子はその表面がフラーレンで被覆されている。以下、フラーレン被覆シリカ粒子を単に「被覆粒子」と言うことがある。また。被覆されていないシリカ粒子を「原料シリカ粒子」と言うことがある。
(Fullerene-coated silica particles)
The surface of the fullerene-coated silica particles of the present embodiment is coated with fullerene. Hereinafter, the fullerene-coated silica particles may be simply referred to as "coated particles". again. Silica particles that are not coated are sometimes referred to as "raw silica particles".

被覆粒子の形状は、樹脂充填用途であれば、一般的な樹脂充填用シリカ粒子と同様であり、球状で、所望する充填密度を得やすい粒度分布を持っていることが好ましい。 The shape of the coated particles is the same as that of general resin-filled silica particles for resin-filling applications.

前記フラーレンは、被覆粒子表面からの脱落し難さの観点から、シリカ粒子表面に化学吸着していることが好ましい。後述する比較例1で示したように、通常、トルエンなどフラーレンを高濃度で溶解できる溶媒(以下、「良溶媒」と言うことがある。)中では、フラーレンはシリカに吸着しない。そのため、後述する各実施例で示されるように、良溶媒中で被覆粒子表面から溶出しないフラーレンは、シリカ粒子表面に化学吸着していると判断できる。この化学吸着では、フラーレンの炭素原子とシリカのケイ素原子とが酸素原子を介して化学結合していることが推定される。 The fullerene is preferably chemically adsorbed on the silica particle surface from the viewpoint of difficulty in falling off from the coated particle surface. As shown in Comparative Example 1, which will be described later, fullerene does not adsorb to silica in a solvent such as toluene that can dissolve fullerene at a high concentration (hereinafter sometimes referred to as a "good solvent"). Therefore, as shown in each example described later, it can be determined that fullerenes that are not eluted from the coated particle surface in a good solvent are chemically adsorbed on the silica particle surface. In this chemisorption, it is presumed that the carbon atom of fullerene and the silicon atom of silica are chemically bonded via oxygen atoms.

前記フラーレンは、C60、C70、より高次のフラーレン、またはそれらの混合物であってもよく、工業的な入手しやすさやコストの観点から前記混合物が好ましく、後述する樹脂組成物の粘度や樹脂硬化物の絶縁破壊電圧の観点からはC60がより好ましい。なお、前記混合物は、樹脂組成物の粘度や樹脂硬化物の絶縁破壊電圧の観点から、C60が質量比で最も多く含まれることがより好ましく、C60が50質量%超含まれることがより好ましい。 The fullerene may be C 60 , C 70 , higher fullerene, or a mixture thereof, and the mixture is preferable from the viewpoint of industrial availability and cost. C60 is more preferable from the viewpoint of the dielectric breakdown voltage of the cured resin. In addition, from the viewpoint of the viscosity of the resin composition and the dielectric breakdown voltage of the cured resin, the mixture preferably contains the largest amount of C60 in terms of mass ratio, and more preferably contains more than 50% by mass of C60 . preferable.

被覆粒子のフラーレン被覆量は、シリカ粒子の表面積当たりのフラーレンの質量で表すことができる。より高い絶縁破壊電圧の樹脂硬化物を得る観点から、被覆粒子のフラーレン被覆量は、0.02~1.6mg/mが好ましく、0.05~1.4mg/mがより好ましく、0.1~1.1mg/mがさらに好ましい。 The fullerene coating amount of the coated particles can be represented by the mass of fullerenes per surface area of the silica particles. From the viewpoint of obtaining a cured resin product with a higher dielectric breakdown voltage, the fullerene coating amount of the coated particles is preferably 0.02 to 1.6 mg/m 2 , more preferably 0.05 to 1.4 mg/m 2 , and 0 .1 to 1.1 mg/m 2 is more preferred.

また、より低粘度の樹脂組成物を得る観点から、被覆粒子のフラーレン被覆量は、多いほどよい傾向があり、0.05mg/m以上が好ましく、0.5mg/m以上がより好ましく、0.9mg/m以上がさらに好ましく、1.2mg/m以上が特に好ましい。ただし、被覆粒子のフラーレン被覆量の上限は、フラーレン分子が最密重点でシリカ粒子表面に1層並んだ状態の被覆量に等しく、分子直径約1nmのC60の場合、約1.6mg/mとなる。 In addition, from the viewpoint of obtaining a resin composition with a lower viscosity, the higher the fullerene coating amount of the coated particles, the better. 0.9 mg/m 2 or more is more preferable, and 1.2 mg/m 2 or more is particularly preferable. However, the upper limit of the fullerene coating amount of the coated particles is equal to the coating amount when the fullerene molecules are arranged in one layer on the silica particle surface at the close-packed point, and in the case of C60 with a molecular diameter of about 1 nm, it is about 1.6 mg / m 2 .

前記被覆量は、後述する実施例のように製造時のフラーレンのシリカ粒子への吸着量から求められる。ただし、前記吸着量が不明の場合は、被覆量既知の被覆粒子で検量線を作成して、被覆粒子の色、あるいは、ToF-SIMS(飛行時間型二次イオン質量分析法)で得られるフラーレンのピーク強度などから被覆量を求めてもよい。 The amount of coating is determined from the amount of fullerene adsorbed to the silica particles during production, as in Examples described later. However, if the adsorption amount is unknown, a calibration curve is created with coated particles with a known coating amount, and the color of the coated particles or the fullerene obtained by ToF-SIMS (time-of-flight secondary ion mass spectrometry) The amount of coating may be obtained from the peak intensity of .

(樹脂組成物)
本実施形態の樹脂組成物は、被覆粒子と硬化性樹脂とを含む。前記硬化性樹脂は、電気絶縁性の観点からエポキシ樹脂が好ましく、電気絶縁用として市販されるエポキシ樹脂であればより好ましく使用できる。
(resin composition)
The resin composition of this embodiment contains coated particles and a curable resin. The curable resin is preferably an epoxy resin from the viewpoint of electrical insulation, and more preferably an epoxy resin commercially available for electrical insulation.

前記エポキシ樹脂としては、例えば、フェノールノボラック型エポキシ樹脂、クレゾールノボラック型エポキシ樹脂、ビスフェノール型エポキシ樹脂、ビフェノール型エポキシ樹脂、ナフタレン骨格含有エポキシ樹脂、複素環式エポキシ樹脂等を挙げることができる。 Examples of the epoxy resin include phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol type epoxy resin, biphenol type epoxy resin, naphthalene skeleton-containing epoxy resin, and heterocyclic epoxy resin.

硬化性樹脂がエポキシ樹脂である場合など、前記樹脂組成物は、硬化に必要な硬化剤、さらに硬化促進剤、などを含んでもよい。被覆粒子を除き、硬化性樹脂、硬化剤及び硬化促進剤などの前記樹脂組成物の成分は、特に限定されず、目的に応じて市販品から選択してもよい。前記樹脂組成物は、被覆粒子とこれら成分とを混錬するなどして得ることができる。 When the curable resin is an epoxy resin, the resin composition may contain a curing agent necessary for curing, a curing accelerator, and the like. Except for the coated particles, the components of the resin composition such as the curable resin, curing agent, and curing accelerator are not particularly limited, and may be selected from commercial products depending on the purpose. The resin composition can be obtained by kneading the coated particles and these components.

樹脂組成物の粘度は、前述の様に被覆粒子の被覆量が多くなるほど低くなることから、前記被覆量を調整して所望の粘度を得てもよい。 Since the viscosity of the resin composition decreases as the coating amount of the coated particles increases as described above, a desired viscosity may be obtained by adjusting the coating amount.

(樹脂硬化物)
本実施形態の樹脂硬化物は、前記樹脂組成物を硬化させたものである。硬化の方法は特に制限されないが、熱、光、必要に応じて、さらに硬化剤や硬化促進剤を添加して硬化させてもよい。このような樹脂硬化物は良好な電気絶縁材料となる。
(resin cured product)
The cured resin product of the present embodiment is obtained by curing the resin composition. The curing method is not particularly limited, but curing may be performed by adding heat, light, and, if necessary, a curing agent or a curing accelerator. Such a resin cured product becomes a good electrical insulating material.

(フラーレン被覆シリカ粒子の製造方法)
被覆粒子の製造方法は、フラーレンが溶解している溶液中で原料シリカ粒子に機械的シェアをかける工程を有する。以下、この工程を「本工程」と言うことがある。原料シリカ粒子へのフラーレンの吸着は、前記機械的シェアがより強いほど、また、前記溶液中のフラーレン濃度がより高いほど、速く進む。また、原料シリカ粒子へのフラーレンの被覆量は、前述の吸着量の上限に達するまでは、機械的シェアをかける時間が長いほど高くなる。これらを調整することにより所望する被覆量の被覆粒子を得ることができる。
(Method for producing fullerene-coated silica particles)
The method for producing coated particles has a step of subjecting raw material silica particles to mechanical shear in a solution in which fullerene is dissolved. Hereinafter, this step may be referred to as "main step". Adsorption of fullerenes to the raw silica particles proceeds faster the stronger the mechanical shear and the higher the fullerene concentration in the solution. In addition, the coating amount of fullerenes on the raw material silica particles increases as the mechanical shear is applied for a longer time until the upper limit of the adsorption amount is reached. By adjusting these parameters, coated particles having a desired coating amount can be obtained.

(原料シリカ粒子)
前記原料シリカ粒子は特に制限されないが、得られる樹脂硬化物を電気絶縁材料として用いる場合は、球状で、高密度で充填しやすい粒度分布を持つシリカ粒子であることが好ましい。前記粒度分布の範囲は、通常、0.1μm~1mm程度である。
(Raw material silica particles)
The raw material silica particles are not particularly limited, but when the resulting resin cured product is used as an electrical insulating material, silica particles that are spherical and have a particle size distribution that facilitates filling at a high density are preferable. The range of the particle size distribution is usually about 0.1 μm to 1 mm.

(フラーレン溶液)
前記フラーレン溶液は、得られる被覆粒子の被覆に必要な量のフラーレンを含むことが好ましい。このようにすることで、フラーレン溶液を換えることなく本工程を1回行うだけで済ますことができる。本工程で前記吸着が進むとフラーレン溶液のフラーレン濃度が低下する。このため、吸着が進んでも吸着速度を高く維持する観点から、フラーレン溶液中に溶解しているフラーレン量は、前記必要量の1.1倍以上が好ましく、2倍以上がより好ましく、5倍以上がさらに好ましい。ただし、後述する実施例のように、フラーレン濃度変化から吸着量を算出する場合は、前記フラーレン量が多くなるほど濃度変化は少なくなり、高精度で吸着量を測定することは難くなる。そのため、前記フラーレン量は10倍以下が好ましい。
(fullerene solution)
The fullerene solution preferably contains an amount of fullerene necessary for coating the resulting coated particles. By doing so, it is possible to perform this step only once without changing the fullerene solution. As the adsorption progresses in this step, the fullerene concentration of the fullerene solution decreases. Therefore, from the viewpoint of maintaining a high adsorption rate even if adsorption progresses, the amount of fullerene dissolved in the fullerene solution is preferably 1.1 times or more, more preferably 2 times or more, and 5 times or more of the required amount. is more preferred. However, when the adsorption amount is calculated from the fullerene concentration change as in the example described later, the concentration change decreases as the fullerene amount increases, making it difficult to measure the adsorption amount with high accuracy. Therefore, the amount of fullerene is preferably 10 times or less.

前記フラーレン溶液の溶媒は、フラーレンを溶解できる溶媒であればよく、フラーレン溶液の体積を少なくできる観点から、良溶媒であるほど好ましい。また、良溶媒を用いた場合、原料シリカ粒子へのフラーレンの物理吸着が生じにくく、吸着するフラーレンのほぼ全量を化学吸着させることができる。このような良溶媒として、トルエンやキシレンなどのアルキルベンゼンが挙げられる。 The solvent for the fullerene solution may be a solvent capable of dissolving the fullerene, and from the viewpoint of reducing the volume of the fullerene solution, the better the solvent, the better. In addition, when a good solvent is used, physical adsorption of fullerenes to raw material silica particles is less likely to occur, and substantially the entire amount of adsorbed fullerenes can be chemically adsorbed. Examples of such a good solvent include alkylbenzenes such as toluene and xylene.

(機械的シェア)
前記機械的シェアの強さは、原料シリカ粒子に均一にフラーレンを被覆する観点から、原料シリカ粒子の凝集粒を分散できることが好ましく、また、より高い絶縁破壊電圧の樹脂硬化物を得る観点から、原料シリカ粒子が粉砕されないことが好ましい。すなわち、原料シリカ粒子が解砕される範囲で機械的シェアをかけることが好ましい。また、取扱いの観点から、前記機械的シェアの強度は、本工程に要する時間が0.5~200時間程度になるような範囲に調整することが好ましい。
(mechanical share)
The strength of the mechanical shear is preferably capable of dispersing aggregated particles of the raw material silica particles from the viewpoint of uniformly coating the raw material silica particles with fullerene, and from the viewpoint of obtaining a resin cured product with a higher dielectric breakdown voltage, It is preferred that the raw silica particles are not pulverized. That is, it is preferable to apply mechanical shear within a range in which the raw material silica particles are pulverized. From the viewpoint of handling, it is preferable to adjust the strength of the mechanical shear so that the time required for this step is about 0.5 to 200 hours.

このような機械的シェアをかける装置としては、前記フラーレン溶液中で原料シリカ粒子に機械的シェアをかけられるものであれば特に制限はないが、前記本工程に要する時間内で原料シリカ粒子を解砕しやすい装置が好ましく、例えば、ビーズミルなどが挙げられる。 The apparatus for applying such a mechanical shear is not particularly limited as long as it can apply a mechanical shear to the raw silica particles in the fullerene solution, but the raw silica particles are loosened within the time required for the main step. A friable device is preferred, such as a bead mill.

(被覆粒子の回収)
本工程終了後、フラーレン溶液から被覆粒子を回収する。特に回収方法は制限されないが、例えば、ビーズミルを用いた場合、ビーズを篩分して除き、次に濾過により被覆粒子を回収することができる。回収した被覆粒子は、乾燥させずにそのまま樹脂組成物の製造に用いることが好ましく、あるいは、乾燥させる場合は、回収した被覆粒子をフラーレンの良溶媒などで洗浄し、被覆粒子表面からフラーレン溶液を除去してから乾燥することが好ましい。このようにすると、被覆粒子表面でのフラーレンの凝集粒の発生を防ぐことができ、より高い絶縁破壊電圧の樹脂硬化物を得やすい。
(Recovery of coated particles)
After completing this step, the coated particles are recovered from the fullerene solution. Although the recovery method is not particularly limited, for example, when a bead mill is used, the beads can be removed by sieving, and then the coated particles can be recovered by filtration. The recovered coated particles are preferably used as they are for the production of the resin composition without being dried. Alternatively, in the case of drying, the recovered coated particles are washed with a good solvent for fullerenes, etc., and the fullerene solution is removed from the surfaces of the coated particles. Drying after removal is preferred. By doing so, generation of aggregated fullerene particles on the surface of the coated particles can be prevented, and a cured resin product having a higher dielectric breakdown voltage can be easily obtained.

以下に本発明の実施例を示し、本発明をより具体的に説明する。なお、これらは説明のための単なる例示であって、本発明はこれらによって何ら制限されるものではない。 EXAMPLES The present invention will be explained more specifically below by showing examples of the present invention. These are merely examples for explanation, and the present invention is not limited by these.

測定方法:
(フラーレン濃度の測定)
フラーレン溶液等の溶液を試料とし、波長308nmの吸光度を測定することによりフラーレン濃度を求めた。検量線は用いたフラーレンのトルエン溶液で作成した。なお、溶液中にシリカ粒子などの不溶物がある場合は、試料を静置して上澄みの吸光度を測定した。
Measuring method:
(Measurement of fullerene concentration)
A solution such as a fullerene solution was used as a sample, and the fullerene concentration was obtained by measuring the absorbance at a wavelength of 308 nm. A calibration curve was created with the toluene solution of the fullerene used. When the solution contained insoluble matter such as silica particles, the sample was allowed to stand and the absorbance of the supernatant was measured.

(フラーレンの被覆量)
後述する磁器ポットに投入前と取り出し後のフラーレン溶液中のフラーレン濃度を測定し、その差から下記式の通り求めた。なお、被覆量はシリカ粒子の表面積当たりのフラーレンの質量として表した。
被覆量(mg/m)=10×(C-C)×V/(S×W)
ただし、C:磁器ポットに投入前のフラーレン溶液中のフラーレン濃度(質量%)
:磁器ポットから取り出し後のフラーレン溶液中のフラーレン濃度(質量%)
V:フラーレン溶液の質量(g)
S:シリカ粒子の比表面積(m/g)
W:シリカ粒子の質量(g)
である。
(Fullerene coating amount)
The fullerene concentration in the fullerene solution was measured before and after it was put into a later-described porcelain pot, and the difference was calculated according to the following formula. The coating amount was expressed as the mass of fullerene per surface area of silica particles.
Coating amount (mg/m 2 ) = 10 x (C 0 -C 1 ) x V/(S x W)
However, C 0 : fullerene concentration in the fullerene solution before being put into the porcelain pot (% by mass)
C 1 : fullerene concentration in the fullerene solution after being taken out from the porcelain pot (% by mass)
V: mass of fullerene solution (g)
S: specific surface area of silica particles (m 2 /g)
W: mass of silica particles (g)
is.

なお、前記比表面積は、BET一点法で測定した。具体的には、Mountech社製 Macsorb(登録商標)HM model-1201全自動比表面積系測定装置を用い、測定用セルへのシリカ粒子充填量は1gとし、測定前の脱気条件は200℃-10分とし、吸着ガスは窒素とし、比表面積を測定した。 The specific surface area was measured by the BET single-point method. Specifically, using a Macsorb (registered trademark) HM model-1201 fully automatic specific surface area measuring device manufactured by Mounttech, the amount of silica particles filled in the measurement cell was 1 g, and the degassing conditions before measurement were 200 ° C.- The specific surface area was measured using nitrogen as the adsorption gas for 10 minutes.

(絶縁破壊電圧の測定)
フラーレン被覆シリカ粒子等のシリカ粒子を試料として、以下の通り、試料を充てん剤として用いた樹脂硬化物シートを作製し、その絶縁破壊電圧を測定した。
(Measurement of dielectric breakdown voltage)
Using silica particles such as fullerene-coated silica particles as a sample, a cured resin sheet was prepared using the sample as a filler, and the dielectric breakdown voltage was measured.

380質量部の試料と100質量部のエポキシ樹脂(三菱化学社製、JER828)と80質量部の硬化剤(日立化成社製、HN-2200)と1質量部の硬化促進剤(和光純薬工業社製、1-シアノエチル-2-エチル-4-メチルイミダゾール)とを混合し樹脂組成物を得た。この樹脂組成物を枠に流し入れ、70℃、12時間の加熱硬化を行い、50mm角の厚さ1mmの樹脂シート(樹脂硬化物)を作製した。 380 parts by mass of sample, 100 parts by mass of epoxy resin (Mitsubishi Chemical Co., Ltd., JER828), 80 parts by mass of curing agent (Hitachi Chemical Co., Ltd., HN-2200) and 1 part by mass of curing accelerator (Wako Pure Chemical Industries, Ltd. 1-cyanoethyl-2-ethyl-4-methylimidazole manufactured by Co., Ltd.) to obtain a resin composition. This resin composition was poured into a frame and heat-cured at 70° C. for 12 hours to prepare a 50 mm square resin sheet (resin cured product) having a thickness of 1 mm.

絶縁破壊試験装置YST-243-100RH0(ヤマヨ試験器社製)を用い、JIS C2110-1:2016に準拠し、作製した樹脂シートの絶縁破壊電圧を20秒段階法にて測定した。すなわち、絶縁破壊電圧を測定する箇所のシートの厚さを正確に測定し、次に、樹脂シートをシリコン油浴中に入れて、樹脂シートを厚さ方向から電極(円柱状で樹脂シートに接する端面は直径25mmの円形)で挟み、所定の印加電圧で20秒間絶縁破壊されなければ、昇圧を繰り返し、絶縁破壊される前の電圧を絶縁破壊電圧とした。前記印加電圧は、20kVまでは1kVずつ昇圧し、20kVを超えてから2kVずつ昇圧した。なお、この測定は気温23±2℃、湿度50±5%RHの環境下で行った。 Using a dielectric breakdown tester YST-243-100RH0 (manufactured by Yamayo Test Instruments Co., Ltd.), the dielectric breakdown voltage of the produced resin sheet was measured according to JIS C2110-1:2016 by a 20-second step method. That is, the thickness of the sheet at the location where the dielectric breakdown voltage is to be measured is accurately measured, then the resin sheet is placed in a silicon oil bath, and the resin sheet is brought into contact with the electrode (columnar shape) from the thickness direction. The end face was sandwiched by a circle with a diameter of 25 mm), and if the dielectric breakdown did not occur for 20 seconds at a predetermined applied voltage, the voltage was repeatedly increased, and the voltage before dielectric breakdown was taken as the dielectric breakdown voltage. The applied voltage was increased by 1 kV up to 20 kV, and increased by 2 kV after exceeding 20 kV. This measurement was performed under an environment of temperature 23±2° C. and humidity 50±5% RH.

(粘度の測定)
絶縁破壊電圧の測定で作製した樹脂組成物を試料として、コーンプレート型のE型粘度計(BROOKFIELD社製)に試料約0.2gを装填して、せん断速度100s-1、気温25℃の条件下で粘度を測定した。
(Measurement of viscosity)
Using the resin composition prepared in the measurement of the dielectric breakdown voltage as a sample, about 0.2 g of the sample was loaded into a cone plate type E-type viscometer (manufactured by BROOKFIELD), and the shear rate was 100 s -1 and the temperature was 25 ° C. Viscosity was measured below.

実施例1:
(フラーレン被覆シリカの作製)
フラーレンC60(フロンティアカーボン社製、ナノム(登録商標)パープル、C60純度99.5質量%以上、不純物としてC70以上の高次のフラーレンを0.5質量%以下含む)を0.5質量%の濃度となるようにトルエン(関東化学社製)に溶解し、フラーレン溶液を得た。このフラーレン溶液100gと原料シリカ(デンカ社製、球状シリカFB-304、比表面積3.4m/g)30gとを混合し、原料シリカの分散液を得た。
次に、直径1.5mmのジルコニア製ビーズ約705gが入っている内容量415mlのアルミナ製の磁製ポットに、前記分散液を投入し、密封し、水平型のポットミル架台に載せ、150rpmで192時間回転させることにより原料シリカ粒子に機械的シェアをかけた。なお、ポットを回転させる時間、すなわち機械的シェアをかける時間を「反応時間」と呼ぶことがある。 次にポットから内容物を取り出し、目の開き1mmの篩でビーズを除き、次にろ過してフラーレン被覆シリカ粒子を回収した。回収した被覆粒子は、トルエンで洗浄後、真空乾燥機で70℃,36時間乾燥し、以後の操作や測定に用いた。表1に、フラーレン被覆量の測定、粘度の測定、絶縁破壊電圧の測定の各結果を示す。
Example 1:
(Preparation of fullerene-coated silica)
Fullerene C 60 (manufactured by Frontier Carbon, Nanom (registered trademark) purple, C 60 purity 99.5 mass% or more, containing 0.5 mass% or less of C 70 or higher fullerene as an impurity) 0.5 mass %, to obtain a fullerene solution. 100 g of this fullerene solution and 30 g of starting silica (Spherical silica FB-304 manufactured by Denka, specific surface area 3.4 m 2 /g) were mixed to obtain a dispersion of starting silica.
Next, the dispersion was poured into a porcelain pot made of alumina with a capacity of 415 ml containing about 705 g of zirconia beads with a diameter of 1.5 mm. A mechanical shear was applied to the starting silica particles by rotating them for a time. Note that the time for rotating the pot, that is, the time for mechanical shearing, is sometimes referred to as "reaction time." Next, the content was taken out from the pot, beads were removed with a sieve with an opening of 1 mm, and then filtered to recover the fullerene-coated silica particles. The recovered coated particles were washed with toluene, dried in a vacuum dryer at 70° C. for 36 hours, and used for subsequent operations and measurements. Table 1 shows the results of fullerene coating amount measurement, viscosity measurement, and dielectric breakdown voltage measurement.

(フラーレン被覆シリカ粒子表面の分析)
本実施例で得られた被覆粒子について、その表面をToF-SIMS(飛行時間型二次イオン質量分析法)で調べた。ネガティブイオンのスペクトルではC60に相当するm/z720のピークのみが確認された。ポジティブイオンのスペクトルでは、最も強いC60に相当するm/z720のピーク、C60のC周期の複数のピーク、及び、わずかにC70以上の高次のフラーレンに相当する複数のピークが確認された。なお、これら高次のフラーレンのピークは原料C60製品の不純物由来と考えられる。
(Analysis of fullerene-coated silica particle surface)
The surface of the coated particles obtained in this example was examined by ToF-SIMS (time-of-flight secondary ion mass spectrometry). Only a peak at m/z 720 corresponding to C60 was confirmed in the negative ion spectrum. In the spectrum of positive ions, a peak at m/z 720 corresponding to the most intense C60 , multiple peaks in the C2 period of C60 , and multiple peaks slightly corresponding to higher fullerenes of C70 or higher are confirmed. was done. These higher-order fullerene peaks are considered to be derived from impurities in the raw material C60 product.

また、実体顕微鏡で粒子表面の観察を行った。本実施例で得られた被覆粒子の形状は、球状のままで原料シリカ粒子の形状との差は認められなかった。また、原料シリカ粒子と得られた被覆粒子との比表面積の差も認められなかった。原料シリカ粒子は白色であったが、被覆粒子は均一に褐色であった。さらに、被覆粒子0.5gをトルエン20gに投入して70時間攪拌した後、トルエン中にフラーレンは検出されず、被覆粒子の色に変化は無かった。 In addition, the particle surface was observed with a stereoscopic microscope. The shape of the coated particles obtained in this example remained spherical, and no difference from the shape of the starting silica particles was observed. Moreover, no difference in specific surface area was observed between the starting silica particles and the obtained coated particles. The raw silica particles were white, but the coated particles were uniformly brown. Furthermore, after 0.5 g of the coated particles were put into 20 g of toluene and stirred for 70 hours, no fullerene was detected in the toluene and the color of the coated particles did not change.

比較例1:
フラーレン溶液としてフラーレンの飽和溶液(約3質量%)を用いたこと、磁製ポットを回転させずに189時間放置した(すなわち反応時間は0である)ことを除き、実施例1と同様の操作を行った。この操作で得られた粒子は、被覆量が0であったことから、原料シリカ粒子のままであることが分かった。
Comparative Example 1:
The same procedure as in Example 1, except that a saturated fullerene solution (about 3% by mass) was used as the fullerene solution, and the porcelain pot was left for 189 hours without rotating (that is, the reaction time was 0). did Since the particles obtained by this operation had a coating amount of 0, it was found that they were raw silica particles as they were.

上記実施例1及び比較例1の結果より、ToF-SIMSによる分析から被覆粒子表面にはフラーレンが存在していることが分かった。ただし、比較例1のように機械的シェアをかけない状態ではフラーレンはシリカに吸着しなかった。被覆粒子を良溶媒のトルエンに浸漬してもフラーレンの溶出は見られなかった。これらのことから被覆粒子のフラーレンはシリカ粒子に化学吸着していると考えられる。また、被覆粒子の色は、表面にフラーレンが吸着して生じたものと考えられる。 From the results of Example 1 and Comparative Example 1, analysis by ToF-SIMS revealed that fullerene was present on the surface of the coated particles. However, as in Comparative Example 1, fullerene was not adsorbed to silica in a state where mechanical shear was not applied. No elution of fullerene was observed even when the coated particles were immersed in toluene, which is a good solvent. From these facts, it is considered that the fullerene of the coated particles is chemically adsorbed on the silica particles. In addition, it is considered that the color of the coated particles is caused by the adsorption of fullerene on the surface.

実施例2~5:
60の代わりにフラーレン混合物(フロンティアカーボン社製、ナノム(登録商標)ミックス、C60約60質量%、C70約30質量%、C70より大きい高次のフラーレン約10質量%を含有する)を用いたこと、及び、フラーレン溶液中のフラーレン濃度及び反応時間を表1に記載の通りとしたことを除き、実施例1と同様の操作及び測定を行った。また、フラーレン被覆量の測定、粘度の測定、絶縁破壊電圧の測定の各結果を表1、図1及び図2に示した。
Examples 2-5:
Fullerene mixture (manufactured by Frontier Carbon Co., Ltd., Nanom (registered trademark) mix, containing about 60% by mass of C60 , about 30% by mass of C70 , and about 10% by mass of fullerenes higher than C70 ) instead of C60 was used, and the fullerene concentration and reaction time in the fullerene solution were set as shown in Table 1, and the same operations and measurements as in Example 1 were performed. Table 1, FIGS. 1 and 2 show the results of the fullerene coating amount measurement, viscosity measurement, and dielectric breakdown voltage measurement.

(フラーレン被覆シリカ粒子表面の分析)
実施例2~5で得られた被覆粒子の実体顕微鏡観察を行った。いずれの被覆粒子の形状も球状のままであり原料シリカ粒子の形状との差は認められなかった。なお、原料シリカ粒子と得られたいずれの被覆粒子との比表面積の差も認められなかった。また、被覆粒子の色は、均一に褐色であり、実施例2で得たものが最も淡く、実施例3、4、5で得たものの順に濃くなっていた。これより被覆粒子の色は、被覆量が多いほど濃くなることが分かった。
(Analysis of fullerene-coated silica particle surface)
The coated particles obtained in Examples 2 to 5 were observed with a stereoscopic microscope. The shape of all the coated particles remained spherical, and no difference from the shape of the starting silica particles was observed. No difference in specific surface area was observed between the starting silica particles and any of the obtained coated particles. Moreover, the color of the coated particles was uniformly brown. From this, it was found that the color of the coated particles becomes darker as the amount of coating increases.

比較例2:
実施例1で用いた原料シリカ(デンカ社製、FB-304)、すなわち被覆量0のシリカ粒子について、粘度測定及び絶縁破壊電圧の測定を行った。結果を表1、図1及び図2に示した。
Comparative Example 2:
The raw material silica (FB-304 manufactured by Denka Co., Ltd.) used in Example 1, that is, silica particles with a coating amount of 0, was subjected to viscosity measurement and dielectric breakdown voltage measurement. The results are shown in Table 1, Figures 1 and 2.

比較例3:
トルエン(関東化学社製)100gにシランカップリング剤(信越化学工業社製、KBM-403、成分3-グリシドキシプロピルトリメトキシシラン)を0.6質量%の濃度となるように溶解した。この溶液に原料シリカ(デンカ社製、FB-304)30gを添加し24時間攪拌しながら分散させた。この分散液をろ過してシランカップリング剤被覆シリカ粒子を回収した。回収したシランカップリング剤被覆シリカ粒子を、トルエンで洗浄し、真空乾燥機で70℃,36時間乾燥し、以後の操作や測定に用いた。この回収したシリカ全量の質量は、原料シリカより0.163g増えていた。この増加量はシランカップリング剤の結合量に相当する。これより得られたシリカ粒子のシランカップリング剤の被覆量は0.162g/mとなった。表1に、粘度の測定及び絶縁電圧の測定の結果を示す。
Comparative Example 3:
A silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403, component 3-glycidoxypropyltrimethoxysilane) was dissolved in 100 g of toluene (manufactured by Kanto Chemical Co., Ltd.) to a concentration of 0.6 mass %. 30 g of raw material silica (FB-304 manufactured by Denka) was added to this solution and dispersed with stirring for 24 hours. This dispersion was filtered to recover silane coupling agent-coated silica particles. The recovered silane coupling agent-coated silica particles were washed with toluene, dried in a vacuum dryer at 70° C. for 36 hours, and used for subsequent operations and measurements. The total mass of the recovered silica was 0.163 g more than the starting silica. This increased amount corresponds to the bonding amount of the silane coupling agent. The silica particles thus obtained had a coating amount of the silane coupling agent of 0.162 g/m 2 . Table 1 shows the results of viscosity measurements and insulation voltage measurements.

比較例4:
トルエンの代わりにジメチルホルムアミドを用いたこと、フラーレン溶液の代わりに水酸化フラーレン(フロンティアカーボン社製、nanom(登録商標) spectra D100)0.155gをジメチルホルムアミド17.66gに溶解した溶液を用いたこと、反応時間を120時間としたこと、及び、真空乾燥機での乾燥を120℃,24時間行ったことを除き、実施例1と同様の操作及び測定を行った。また、表1に、フラーレン被覆量の測定、粘度の測定、絶縁破壊電圧の測定の各結果を示す。
Comparative Example 4:
Dimethylformamide was used instead of toluene, and a solution obtained by dissolving 0.155 g of fullerene hydroxide (manufactured by Frontier Carbon, nano (registered trademark) spectra D100) in 17.66 g of dimethylformamide was used instead of the fullerene solution. , The same operation and measurement as in Example 1 were performed, except that the reaction time was set to 120 hours, and that drying was performed in a vacuum dryer at 120° C. for 24 hours. Table 1 shows the results of the fullerene coating amount measurement, viscosity measurement, and dielectric breakdown voltage measurement.

Figure 2023084801000002
( )内の数値は、フラーレンではなく、シランカップリング剤または水酸化フラーレンに対する値。
Figure 2023084801000002
Values in parentheses are for silane coupling agents or fullerene hydroxides, not for fullerenes.

本発明は、表面がフラーレンで被覆されているシリカ粒子を用いることにより、絶縁破壊電圧の向上した樹脂硬化物を得ることができる。従って、本発明は、電気機器等の絶縁部に用いる絶縁材料に好ましく適用できる。 In the present invention, by using silica particles whose surfaces are coated with fullerenes, it is possible to obtain cured resin products with improved dielectric breakdown voltage. Therefore, the present invention can be preferably applied to insulating materials used for insulating parts of electrical equipment and the like.

Claims (9)

表面がフラーレンで被覆されているシリカ粒子。 Silica particles whose surface is coated with fullerene. 前記フラーレンはシリカ粒子表面に化学吸着している請求項1に記載のシリカ粒子。 2. The silica particles according to claim 1, wherein the fullerene is chemically adsorbed on the silica particle surface. 前記フラーレンはC60が質量比で最も多く含まれる請求項1または2に記載のシリカ粒子。 3. The silica particles according to claim 1 or 2, wherein the fullerene contains the most C60 in mass ratio. 前記シリカ粒子の表面積当たりのフラーレンの被覆量が0.02~1.60mg/mである請求項1~3のいずれかに記載のシリカ粒子。 The silica particles according to any one of claims 1 to 3, wherein the amount of fullerene coating per surface area of the silica particles is 0.02 to 1.60 mg/m 2 . 請求項1~4のいずれかに記載のシリカ粒子と硬化性樹脂とを含む樹脂組成物。 A resin composition comprising the silica particles according to any one of claims 1 to 4 and a curable resin. 請求項5に記載の樹脂組成物を硬化させた樹脂硬化物。 A cured resin obtained by curing the resin composition according to claim 5 . 請求項6に記載の樹脂硬化物からなる電気絶縁材料。 An electrical insulating material comprising the cured resin according to claim 6 . フラーレンが溶解している溶液中で原料シリカ粒子に機械的シェアをかける工程を有する請求項1~4のいずれかに記載のシリカ粒子の製造方法。 5. The method for producing silica particles according to any one of claims 1 to 4, comprising a step of applying mechanical shear to the raw material silica particles in a solution in which fullerene is dissolved. 前記機械的シェアをかける工程が、原料シリカ粒子を解砕することにより行われる請求項8に記載のシリカ粒子の製造方法。
9. The method for producing silica particles according to claim 8, wherein the step of mechanically shearing is performed by pulverizing raw material silica particles.
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