JP2013177313A - Alumina fine particle and method for producing the same - Google Patents
Alumina fine particle and method for producing the same Download PDFInfo
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本発明は、粒子形態が微細で均一であり、凝集がなく分散性に優れたベーマイト微粒子、アルミナ微粒子及びそれらの製造方法に関する。本発明のベーマイト微粒子及びアルミナ微粒子は、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等の材料として好適に使用することができる。 The present invention relates to boehmite fine particles, alumina fine particles having fine and uniform particle shape, excellent in dispersibility, and a method for producing them. The boehmite fine particles and alumina fine particles of the present invention are abrasive particles, toner external additive particles, paint pigments, rubber / plastic fillers, ceramic materials such as translucent materials and IC substrates, AlN precursors, adsorbents. It can be suitably used as a material for a catalyst carrier or the like.
従来、ベーマイト及びアルミナは、耐食性、電気絶縁性、熱伝導性、機械的強度等の種々の物性に優れ、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、セラミックス原料等の様々な用途に利用されてきた。その用途に合せてベーマイト粒子及びアルミナ粒子に求められている特性は異なるが、微粒子化、均一性、高分散性はどの用途でも特性向上に必要な要素である。 Conventionally, boehmite and alumina are excellent in various physical properties such as corrosion resistance, electrical insulation, thermal conductivity, mechanical strength, abrasive particles, toner external additive particles, paint pigments, rubber / plastic fillers, It has been used for various applications such as ceramic raw materials. Although the characteristics required for boehmite particles and alumina particles differ depending on the application, fine particle formation, uniformity, and high dispersibility are factors necessary for improving the characteristics in any application.
これまで、上記用途のベーマイト粒子及びアルミナ粒子を製造する方法として、様々なベーマイト粒子及びアルミナ粒子の製造方法が提案されている。
一般的なアルミナ粒子の製造方法としては、バイヤー法等で得られた水酸化アルミニウム、又は水酸化アルミニウム等を低温で仮焼することで得られた遷移アルミナ（γ−Ａｌ2Ｏ3、δ−Ａｌ2Ｏ3、θ−Ａｌ2Ｏ3等) を、粉砕・分級等により粒度調整を行った後、焼成することにより、アルミナ粒子を得る方法が挙げられる（例えば特許文献１〜４参照）。また、その焼成時の雰囲気ガスとして、焼成温度の低温化を目的に塩化水素、塩素ガス及び水蒸気の混合ガスを用いたり（例えば特許文献５〜７参照）、平均粒径が１００ｎｍ以下のα−アルミナ粒子を得るために、水素ガスを用いたりしている（例えば特許文献８参照）。しかし、これらの方法では、微粒子化するために粉砕処理を必要とし、また得られるアルミナの粒子形態が不均一で粒度分布も広い。分級処理により粒度分布を狭くすることはできるが、目標の粒子サイズを微細にすれば歩留も悪化する。
So far, various boehmite particles and alumina particle production methods have been proposed as methods for producing boehmite particles and alumina particles for the above applications.
As a general method for producing alumina particles, aluminum hydroxide obtained by the Bayer method or the like, or transition alumina obtained by calcining aluminum hydroxide or the like at a low temperature (γ-Al 2 O 3 , δ- Examples include a method of obtaining alumina particles by calcining (Al 2 O 3 , θ-Al 2 O 3, etc.) after pulverizing and classifying and then firing (see, for example, Patent Documents 1 to 4). In addition, a mixed gas of hydrogen chloride, chlorine gas and water vapor is used as an atmosphere gas at the time of firing for the purpose of lowering the firing temperature (see, for example, Patent Documents 5 to 7), or α- with an average particle size of 100 nm or less. In order to obtain alumina particles, hydrogen gas is used (for example, refer to Patent Document 8). However, these methods require a pulverization process to make fine particles, and the resulting alumina has a non-uniform particle shape and a wide particle size distribution. Although the particle size distribution can be narrowed by classification, the yield is also deteriorated if the target particle size is made fine.
粉砕処理なしでアルミナ微粒子を得る製造方法として、アンモニウムドーソナイト［ＮＨ4ＡｌＣＯ3(ＯＨ）2］熱分解法が知られている（例えば特許文献９参照）。この方法は、一次粒子径が１００ｎｍ程度で高純度のアルミナ微粒子が得られ、セラミックス原料用として使用した場合では低温焼結化が可能である。しかしながら、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラーには高分散性が求められており、この方法で得られるアルミナ微粒子は、凝集粒子であるため、単分散が困難である。また、アルコキシド法、ゾルゲル法を利用した製造方法も、上記方法と同様に、得られるアルミナ微粒子が凝集しやすい。 An ammonium dosonite [NH 4 AlCO 3 (OH) 2 ] thermal decomposition method is known as a production method for obtaining alumina fine particles without pulverization (see, for example, Patent Document 9). In this method, high-purity alumina fine particles having a primary particle diameter of about 100 nm are obtained, and when used as a ceramic raw material, low-temperature sintering is possible. However, abrasive particles, toner external additive particles, paint pigments, rubber / plastic fillers are required to have high dispersibility, and the alumina fine particles obtained by this method are aggregated particles. Dispersion is difficult. In addition, in the production method using the alkoxide method and the sol-gel method, the obtained alumina fine particles are easily aggregated as in the above method.
分散性の良好なアルミナ粒子を得る方法として、水酸化アルミニウム、アルミナ水和物、アルミナの焼成時にフッ素鉱化剤、ハロゲン化合物、ホウ素化合物を添加して球状粒子を得る方法がある（例えば特許文献１０及び１１参照）。しかしながら、この方法は、焼成過程の改良だけであり、粒子サイズが１μｍ以下の均一な微粒子を得るのは困難である。また、その他の球状アルミナ粒子の製造方法として、表面が平滑な真球に近い粒子が得られる噴霧熱分解法、噴霧乾燥法が提案されている（例えば特許文献１２及び１３参照）。これらの方法は、スプレードライヤ等を用いて、Ａｌ含有スラリーを噴霧して液滴化し、乾燥あるいは燃焼することで球状アルミナを得るものである。しかしながら、これらの方法は、球状粒子が得られるものの、液相合成法等と比較して粒度分布が広くなり、粒度分布の狭い粒子を得るためには分級工程等が必要となる。また、特許文献１２では、噴霧スラリーとしてアルミニウム含有化合物を含有した可燃性液体（灯油、軽油、アルコール）を用いて噴霧した液滴を燃焼させており、可燃性液体を燃焼させるため作業上に爆発等の危険を伴う。特許文献１３では、噴霧スラリーとして硫酸アルミニウムと尿素の酸性水溶液を使用しており、尿素の加水分解によるアンモニアの発生、装置（アトマイザー等）の耐酸性等の対策が必要となる。 As a method of obtaining alumina particles having good dispersibility, there is a method of obtaining spherical particles by adding a fluorine mineralizer, a halogen compound, or a boron compound at the time of firing aluminum hydroxide, alumina hydrate, or alumina (for example, Patent Documents). 10 and 11). However, this method is only an improvement of the firing process, and it is difficult to obtain uniform fine particles having a particle size of 1 μm or less. As other spherical alumina particle production methods, there have been proposed a spray pyrolysis method and a spray drying method in which particles having a smooth surface close to a true sphere are obtained (see, for example, Patent Documents 12 and 13). These methods use a spray dryer or the like to spray Al-containing slurry into droplets, and dry or burn to obtain spherical alumina. However, although these methods can obtain spherical particles, the particle size distribution is wider than the liquid phase synthesis method and the like, and a classification step or the like is required to obtain particles having a narrow particle size distribution. Moreover, in patent document 12, the sprayed droplet is burned using the combustible liquid (kerosene, light oil, alcohol) containing the aluminum containing compound as a spray slurry, and it explodes on work in order to burn a combustible liquid. There is a danger such as. In Patent Document 13, an acidic aqueous solution of aluminum sulfate and urea is used as a spray slurry, and measures such as generation of ammonia by hydrolysis of urea and acid resistance of an apparatus (such as an atomizer) are required.
上記のアルミナ粒子の製造方法と比較して、粒子形態が均一で、粒度分布が狭いベーマイト微粒子及びアルミナ微粒子の製造方法として、水熱反応法が知られている。この水熱反応法は、バイヤー法等により得られた水酸化アルミニウムを粉砕により粒度調整し、結晶制御剤（ＮａＯＨ等）を添加して水熱反応させたり（例えば特許文献１４及び１５参照）、アルミニウム塩水溶液とアルカリ水溶液によりアルミニウムの水酸化物あるいは水和物を水熱反応させたり（例えば特許文献１６〜１８参照）して、ベーマイト微粒子を得、また得られたベーマイト微粒子を高温で焼成してアルミナ微粒子にする方法である。しかしながら、この方法で得られるベーマイト微粒子及びアルミナ微粒子の粒子形態は、アスペクト比（＝粒子径／粒子の厚さ）の高い四角形又は六角形の板状粒子であり、低温の水熱条件で反応させるため、２００ｎｍ以下の微粒子では凝集がひどく、分散が困難である。また、粒子形態が多面体形状のアルミナ粒子が提案されている（例えば特許文献１９及び２０参照）が、平均一次粒子径が５μｍ以上であり、５μｍ以下の微粒子が得られていない。
このように、従来のベーマイト粒子及びアルミナ粒子の製造方法では、粒子の微粒子化、均一性、高分散性を同時に実現するという課題が残されている。
A hydrothermal reaction method is known as a method for producing boehmite fine particles and alumina fine particles having a uniform particle shape and a narrow particle size distribution as compared with the above-described method for producing alumina particles. In this hydrothermal reaction method, the particle size of aluminum hydroxide obtained by the Bayer method or the like is adjusted by pulverization, and a crystal control agent (NaOH or the like) is added to cause a hydrothermal reaction (see, for example, Patent Documents 14 and 15). Boehmite fine particles are obtained by hydrothermal reaction of aluminum hydroxide or hydrate with an aqueous aluminum salt solution and an aqueous alkali solution (see, for example, Patent Documents 16 to 18), and the obtained boehmite fine particles are fired at a high temperature. This is a method of making alumina fine particles. However, the boehmite fine particles and alumina fine particles obtained by this method are rectangular or hexagonal plate-like particles having a high aspect ratio (= particle diameter / particle thickness), and are reacted under low-temperature hydrothermal conditions. Therefore, fine particles of 200 nm or less are agglomerated and are difficult to disperse. Further, although alumina particles having a polyhedral shape have been proposed (see, for example, Patent Documents 19 and 20), the average primary particle diameter is 5 μm or more, and fine particles of 5 μm or less are not obtained.
As described above, in the conventional method for producing boehmite particles and alumina particles, there remains a problem that particles can be made fine, uniform, and highly dispersible at the same time.
本発明は、上記のような事情に鑑みなされたものであり、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等の様々な用途に適した、粒子形態が微細で均一であり、凝集がなく分散性に優れたベーマイト微粒子、アルミナ微粒子及びそれらの製造方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, abrasive particles, particles for external toner additives, paint pigments, rubber and plastic fillers, ceramic raw materials such as translucent materials and IC substrates, To provide boehmite fine particles, alumina fine particles, fine particles having a fine and uniform particle form, excellent in dispersibility, suitable for various uses such as precursors for AlN, adsorbents, catalyst supports, and methods for producing them With the goal.
本発明者らは、上記課題を解決すべく鋭意検討を進めた結果、水熱反応時の水酸化アルミニウム含有水溶液において、アルミニウム（以下、Ａｌとも表記する）、アルカリ及び有機化合物の含有量を特定量とすることにより得られる、特定の平均粒子径、及び特定の有機化合物被覆量を有するベーマイト微粒子及びアルミナ微粒子が、粒子径の制御が可能であり、凝集がなく分散性に優れ、粒子形態が均一であり、特に研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等として使用する場合、粒子の微粒子化、均一性、高分散性等の該用途に要求される性能を有することを見出し、本発明を完成させた。 As a result of intensive studies to solve the above problems, the present inventors have specified the contents of aluminum (hereinafter also referred to as Al), alkali and organic compounds in the aluminum hydroxide-containing aqueous solution during the hydrothermal reaction. The boehmite fine particles and alumina fine particles having a specific average particle size and a specific organic compound coating amount obtained by adjusting the amount can control the particle size, have no aggregation, have excellent dispersibility, and have a particle form. Uniform, especially as abrasive particles, toner additive particles, paint pigments, rubber and plastic fillers, ceramic materials such as translucent materials and IC substrates, precursors for AlN, adsorbents, catalyst carriers, etc. When used, it has been found that it has performances required for such applications such as fine particle formation, uniformity and high dispersibility, and the present invention has been completed.
即ち、本発明は、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ2／ｇ、アスペクト比が３．０以下の板状であるベーマイト微粒子、好ましくは、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ2／ｇ、アスペクト比が３．０以下の板状であって、炭素量が０．０１〜２．０重量％であるベーマイト微粒子を提供するものである。 That is, in the present invention, the median diameter of the particle size distribution is 0.05 to 1.0 μm, the coefficient of variation of the particle size distribution is 45.0% or less, the specific surface area is 1.0 to 150.0 m 2 / g, and the aspect ratio is 3 0.0 or less plate-like boehmite fine particles, preferably, the median diameter of the particle size distribution is 0.05 to 1.0 μm, the variation coefficient of the particle size distribution is 45.0% or less, and the specific surface area is 1.0 to 150.0 m. The present invention provides a boehmite fine particle having a plate shape of 2 / g and an aspect ratio of 3.0 or less and having a carbon content of 0.01 to 2.0% by weight.
また、本発明は、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ2／ｇ、アスペクト比が３．０以下の板状であるアルミナ微粒子、好ましくは、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ2／ｇ、アスペクト比が３．０以下の板状であって、炭素量が０．０１〜２．０重量％であるアルミナ微粒子を提供するものである。 In the present invention, the median diameter of the particle size distribution is 0.05 to 1.0 μm, the coefficient of variation of the particle size distribution is 45.0% or less, the specific surface area is 1.0 to 150.0 m 2 / g, and the aspect ratio is 3 0.0 or less plate-like alumina fine particles, preferably the median diameter of the particle size distribution is 0.05 to 1.0 μm, the coefficient of variation of the particle size distribution is 45.0% or less, and the specific surface area is 1.0 to 150.0 m. The present invention provides an alumina fine particle having a plate shape of 2 / g and an aspect ratio of 3.0 or less and having a carbon content of 0.01 to 2.0% by weight.
また、本発明は、上記の本発明のベーマイト微粒子を製造するための好ましい製造方法として、アルミニウム塩とアルカリとの中和反応により調製した水酸化アルミニウム含有水溶液を水熱反応することを特徴とするベーマイト微粒子の製造方法、好ましくは、該製造方法において、水熱反応前の何れかの段階で、ベーマイトの理論生成量に対して０．０１〜５．０重量％の量の有機化合物を添加し、水酸化アルミニウム含有水溶液中で、水酸化アルミニウムと該有機化合物とを水熱反応することを特徴とするベーマイト微粒子の製造方法を提供するものである。 Further, the present invention is characterized in that as a preferable production method for producing the boehmite fine particles of the present invention, an aqueous solution containing aluminum hydroxide prepared by neutralization reaction between an aluminum salt and an alkali is hydrothermally reacted. In the production method of boehmite fine particles, preferably in the production method, an organic compound is added in an amount of 0.01 to 5.0% by weight with respect to the theoretical amount of boehmite at any stage before the hydrothermal reaction. The present invention also provides a method for producing boehmite fine particles, which comprises hydrothermally reacting aluminum hydroxide and the organic compound in an aqueous solution containing aluminum hydroxide.
また更に、本発明は、上記の本発明のアルミナ微粒子を製造するための好ましい製造方法として、上記の本発明のベーマイト微粒子の製造方法により得られたベーマイト微粒子を、５００〜１０００℃で焼成することを特徴とするアルミナ微粒子の製造方法を提供するものである。 Furthermore, in the present invention, as a preferable production method for producing the alumina fine particles of the present invention, boehmite fine particles obtained by the above-described method for producing boehmite fine particles of the present invention are calcined at 500 to 1000 ° C. A method for producing alumina fine particles characterized by the above is provided.
本発明のベーマイト微粒子及びアルミナ微粒子は、従来のベーマイト粒子及びアルミナ粒子の課題であった粒子の微粒子化、均一化、高分散性を同時に実現しているため、例えば、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等の材料として好適である。 The boehmite fine particles and alumina fine particles of the present invention simultaneously achieve the fine particle formation, homogenization, and high dispersibility, which were the problems of conventional boehmite particles and alumina particles. It is suitable as materials for additive particles, paint pigments, rubber / plastic fillers, ceramic materials such as translucent materials and IC substrates, precursors for AlN, adsorbents, catalyst carriers and the like.
以下、本発明のベーマイト微粒子、アルミナ微粒子及びそれらの製造方法について好ましい実施形態に基づき記述するが、本発明はこれらの記載に限定されるものではない。 Hereinafter, although the boehmite fine particles, the alumina fine particles, and the production methods thereof of the present invention will be described based on preferred embodiments, the present invention is not limited to these descriptions.
本発明者らは、水熱反応前の水酸化アルミニウム含有水溶液のｐＨ調整、特定量の有機化合物の添加、そして適当な水熱反応温度を選択することにより、得られるベーマイト微粒子及びアルミナ微粒子の粒子径、粒子の均一性、分散性を制御できることを見出した。その理由は明らかでないが、次のように推察される。水熱反応温度の上昇に伴ってベーマイト微粒子同士の凝集により粒子成長が促進され、粒子径、アスペクト比は大きくなる。しかし、水酸化アルミニウム含有水溶液のｐＨを制御することで、水熱反応温度が高くなっても低いアスペクト比を維持でき、粒子径のみの制御が可能となる。また、有機化合物、具体的には界面活性剤を添加し、粒子表面を被覆することにより、粒子形態をより均一で、微細なものとできる。これは、水酸化アルミニウム含有水溶液中に界面活性剤が存在した場合、界面活性剤が分散・凝集制御剤、又は緩衝剤として働き、ベーマイト微粒子の水溶液中での均一な粒子成長又は成長抑制に起因するものと考えられる。また、粒子表面での均一な有機化合物の被覆により、水中、有機溶媒、ポリマー等の有機物中での分散性が向上する。また更に、アルミナ微粒子の製造の際、ベーマイト微粒子の表面が有機化合物で被覆されているため、焼成の際、粒子間の凝集及び焼結が起こらず、粒子形態の維持に効果的である。 The present inventors have obtained boehmite fine particles and alumina fine particles obtained by adjusting the pH of an aqueous solution containing aluminum hydroxide before hydrothermal reaction, adding a specific amount of an organic compound, and selecting an appropriate hydrothermal reaction temperature. It has been found that the diameter, particle uniformity, and dispersibility can be controlled. The reason is not clear, but is presumed as follows. As the hydrothermal reaction temperature rises, particle growth is promoted by aggregation of boehmite fine particles, and the particle diameter and aspect ratio increase. However, by controlling the pH of the aluminum hydroxide-containing aqueous solution, a low aspect ratio can be maintained even when the hydrothermal reaction temperature is increased, and only the particle diameter can be controlled. Further, by adding an organic compound, specifically, a surfactant and coating the particle surface, the particle form can be made more uniform and fine. This is because, when a surfactant is present in an aluminum hydroxide-containing aqueous solution, the surfactant acts as a dispersion / aggregation control agent or a buffering agent, and is caused by uniform particle growth or growth suppression in an aqueous solution of boehmite fine particles. It is thought to do. Further, the uniform organic compound coating on the particle surface improves the dispersibility in water, organic solvents, polymers and other organic substances. Furthermore, since the surface of boehmite fine particles is coated with an organic compound during the production of alumina fine particles, aggregation and sintering between particles do not occur during firing, which is effective in maintaining the particle morphology.
まず、本発明のベーマイト微粒子について説明する。
本発明のベーマイト微粒子は、粒子形態が板状であり、そのアスペクト比が３．０以下、好ましくは２．５以下、より好ましくは１．０〜２．０である。アスペクト比が３．０より大きい場合、凝集により分散性が悪く、ポリマー中に分散させたときの充填性が悪い。
First, the boehmite fine particles of the present invention will be described.
The boehmite fine particles of the present invention have a plate shape and an aspect ratio of 3.0 or less, preferably 2.5 or less, more preferably 1.0 to 2.0. When the aspect ratio is larger than 3.0, the dispersibility is poor due to aggregation, and the filling property when dispersed in the polymer is poor.
また、本発明のベーマイト微粒子は、レーザー回折／散乱法により測定した粒度分布のメジアン径が、０．０５〜１．０μｍであり、０．０８〜０．８μｍであることが好ましく、０．１０〜０．５０μｍであることがより好ましい。
また、本発明のベーマイト微粒子は、粒度分布の変動係数が、４５．０％以下であり、４０．０％以下であることが好ましく、３５．０％以下であることがより好ましい。
メジアン径が０．０５μｍより小さい場合、分散性が悪く、凝集により変動係数が大きくなる。メジアン径が１．０μｍより大きい場合、分散性は良いが、アスペクト比が大きくなり、ポリマー中に分散させたときの充填性が悪い。粒度分布の変動係数が４５．０％より大きい場合、凝集により分散性が悪く、ポリマー中に分散させたときの充填性が悪い。
The boehmite fine particles of the present invention have a median diameter of the particle size distribution measured by a laser diffraction / scattering method of 0.05 to 1.0 μm, preferably 0.08 to 0.8 μm, preferably 0.10. More preferably, it is -0.50 micrometer.
Further, the boehmite fine particles of the present invention have a coefficient of variation in particle size distribution of 45.0% or less, preferably 40.0% or less, and more preferably 35.0% or less.
When the median diameter is smaller than 0.05 μm, the dispersibility is poor, and the coefficient of variation increases due to aggregation. When the median diameter is larger than 1.0 μm, the dispersibility is good, but the aspect ratio becomes large, and the fillability when dispersed in the polymer is bad. When the variation coefficient of the particle size distribution is larger than 45.0%, the dispersibility is poor due to aggregation, and the filling property is poor when dispersed in the polymer.
また、本発明のベーマイト微粒子は、比表面積が１．０〜１５０．０ｍ2／ｇであり、５．０〜３０．０ｍ2／ｇであることが好ましく、７．０〜１５．０ｍ2／ｇであることがより好ましい。比表面積が１．０ｍ2／ｇより小さい場合、粒子径が大きく、アスペクト比が大きな微粒子となるため、ポリマー中に分散させたときの充填性が悪く、また比表面積が１５０．０ｍ2／ｇより大きい場合、粒子径が小さく、アスペクト比が大きな微粒子となるため、凝集により分散性が悪く、ポリマー中に分散させたときの充填性が悪い。 Moreover, boehmite particles of the present invention is a specific surface area of 1.0~150.0m 2 / g, is preferably 5.0~30.0m 2 / g, 7.0~15.0m 2 / More preferably, it is g. When the specific surface area is smaller than 1.0 m 2 / g, the particles have a large particle diameter and a large aspect ratio, so that the packing property when dispersed in the polymer is poor, and the specific surface area is 150.0 m 2 / g. If it is larger, fine particles having a small particle diameter and a large aspect ratio are obtained, so that the dispersibility is poor due to aggregation and the filling property when dispersed in a polymer is poor.
本発明のベーマイト微粒子は、有機化合物の添加により微粒子化、均一化、分散性がより一層向上する。有機化合物の添加量は、後述する分析方法により得られる炭素量に換算して、０．０１重量％以上となるように用いることが好ましく、該炭素量が０．０１〜２．０重量％であることがより好ましく、０．１〜１．５重量％であることがより一層好ましい。炭素量が０．０１重量％未満では、微粒子化、均一化、分散性の向上効果が小さい。炭素量が２．０重量％より大きい場合には、有機化合物の添加量を増加させても微粒子化、均一化、分散性への効果が一定となる。
上記有機化合物としては、各種界面活性剤、クエン酸類、アミン類、ポリエチレングリコール（ＰＥＧ）、又はポリビニルアルコール（ＰＶＡ）等の高分子化合物が挙げられ、また、各種有機溶媒を使用しても良い。特に界面活性剤が分散性をより向上させることが可能で、且つ粒子形態への微粒子化、均一化への効果が大きいので好ましい。上記界面活性剤として具体的には、高級脂肪酸及びその塩類、アルキル硫酸エステル塩類、脂肪酸アミン系化合物、アルキルスルホコハク酸塩類等を使用することができ、特にラウリン酸塩、オレイン酸塩、ラウリン酸エステル塩、ドデシルベンゼンスルホン酸塩等が好ましい。
The boehmite fine particles of the present invention are further improved in fineness, homogenization, and dispersibility by adding an organic compound. The amount of the organic compound added is preferably 0.01% by weight or more in terms of the carbon amount obtained by the analytical method described later, and the carbon amount is 0.01 to 2.0% by weight. More preferably, it is 0.1 to 1.5% by weight. When the amount of carbon is less than 0.01% by weight, the effect of improving the atomization, homogenization and dispersibility is small. When the amount of carbon is larger than 2.0% by weight, the effect on the atomization, homogenization, and dispersibility is constant even when the amount of organic compound added is increased.
Examples of the organic compound include polymer surfactants such as various surfactants, citric acids, amines, polyethylene glycol (PEG), and polyvinyl alcohol (PVA), and various organic solvents may be used. In particular, a surfactant is preferable because it can further improve dispersibility and has a large effect on the formation of a fine particle and uniformization into a particle form. Specific examples of the surfactant include higher fatty acids and salts thereof, alkyl sulfate esters, fatty acid amine compounds, alkyl sulfosuccinates, and particularly laurates, oleates, and laurates. Salt, dodecylbenzene sulfonate and the like are preferable.
次に、本発明のアルミナ微粒子について説明する。
本発明のアルミナ微粒子は、上述した本発明のベーマイト微粒子と同様の、粒子形態、アスペクト比、粒度分布のメジアン径、粒度分布の変動係数、及び比表面積を有するものである。
即ち、本発明のアルミナ微粒子は、粒子形態が板状であり、そのアスペクト比が３．０以下、好ましくは２．５以下、より好ましくは１．０〜２.０である。アスペクト比が３．０より大きい場合、凝集により分散性が悪く、ポリマー中に分散させたときの充填性が悪い。
Next, the alumina fine particles of the present invention will be described.
The alumina fine particles of the present invention have the same particle morphology, aspect ratio, median diameter of particle size distribution, coefficient of variation of particle size distribution, and specific surface area as the boehmite fine particles of the present invention described above.
That is, the alumina fine particles of the present invention have a plate shape and an aspect ratio of 3.0 or less, preferably 2.5 or less, more preferably 1.0 to 2.0. When the aspect ratio is larger than 3.0, the dispersibility is poor due to aggregation, and the filling property when dispersed in the polymer is poor.
また、本発明のアルミナ微粒子は、レーザー回折／散乱法により測定した粒度分布のメジアン径が、０．０５〜１．０μｍであり、０．０８〜０．８μｍであることが好ましく、０．１０〜０．５０μｍであることがより好ましい。
また、本発明のアルミナ微粒子は、粒度分布の変動係数が、４５．０％以下であり、４０．０％以下であることが好ましく、３５．０％以下であることがより好ましい。
メジアン径が０．０５μｍより小さい場合、分散性が悪く、凝集により変動係数が大きくなる。メジアン径が１．０μｍより大きい場合、分散性は良いが、アスペクト比が大きくなり、ポリマー中に分散させたときの充填性が悪い。粒度分布の変動係数が４５．０％より大きい場合、凝集により分散性が悪く、ポリマー中に分散させたときの充填性が悪い。
Further, the alumina fine particles of the present invention have a median diameter of the particle size distribution measured by a laser diffraction / scattering method of 0.05 to 1.0 μm, preferably 0.08 to 0.8 μm, preferably 0.10. More preferably, it is -0.50 micrometer.
Further, the alumina fine particles of the present invention have a coefficient of variation in particle size distribution of 45.0% or less, preferably 40.0% or less, and more preferably 35.0% or less.
When the median diameter is smaller than 0.05 μm, the dispersibility is poor, and the coefficient of variation increases due to aggregation. When the median diameter is larger than 1.0 μm, the dispersibility is good, but the aspect ratio becomes large, and the fillability when dispersed in the polymer is bad. When the variation coefficient of the particle size distribution is larger than 45.0%, the dispersibility is poor due to aggregation, and the filling property is poor when dispersed in the polymer.
また、本発明のアルミナ微粒子は、比表面積が１．０〜１５０．０ｍ2／ｇであり、５．０〜１５０．０ｍ2／ｇであることが好ましく、７．０〜１２０．０ｍ2／ｇであることがより好ましい。比表面積が１．０ｍ2／ｇより小さい場合、粒子径が大きく、アスペクト比が大きな微粒子となるため、ポリマー中に分散させたときの充填性が悪く、また比表面積が１５０．０ｍ2／ｇより大きい場合、粒子径が小さく、アスペクト比が大きな微粒子となるため、凝集により分散性が悪く、ポリマー中に分散させたときの充填性が悪い。 Further, alumina fine particles of the present invention is a specific surface area of 1.0~150.0m 2 / g, is preferably 5.0~150.0m 2 / g, 7.0~120.0m 2 / More preferably, it is g. When the specific surface area is smaller than 1.0 m 2 / g, the particles have a large particle diameter and a large aspect ratio, so that the packing property when dispersed in the polymer is poor, and the specific surface area is 150.0 m 2 / g. If it is larger, fine particles having a small particle diameter and a large aspect ratio are obtained, so that the dispersibility is poor due to aggregation and the filling property when dispersed in a polymer is poor.
本発明のアルミナ微粒子も、本発明のベーマイト微粒子と同様、有機化合物の添加により微粒子化、均一化、分散性がより一層向上する。該有機化合物の添加量及び種類は、上述した本発明のベーマイト微粒子における場合と同じである。 Similarly to the boehmite fine particles of the present invention, the alumina fine particles of the present invention are further improved in fineness, homogenization, and dispersibility by the addition of an organic compound. The amount and kind of the organic compound added are the same as in the boehmite fine particles of the present invention described above.
次に、本発明のベーマイト微粒子及びアルミナ微粒子の好ましい製造方法について説明する。
本発明のベーマイト微粒子は、ｉ）水酸化アルミニウム含有水溶液の調製工程と、ii）上記ｉ) の工程で調製した水酸化アルミニウム含有水溶液を水熱反応させる水熱反応工程により製造できる。
また、本発明のアルミナ微粒子は、iii)上記ｉ）及びii) の工程により製造された本発明のベーマイト微粒子を焼成させる焼成工程により製造できる。以下、工程順に説明する。
Next, a preferred method for producing boehmite fine particles and alumina fine particles of the present invention will be described.
The boehmite fine particles of the present invention can be produced by i) a preparation step of an aluminum hydroxide-containing aqueous solution and ii) a hydrothermal reaction step in which the aluminum hydroxide-containing aqueous solution prepared in the step i) is hydrothermally reacted.
Further, the alumina fine particles of the present invention can be produced by a firing step of firing the boehmite fine particles of the present invention produced by iii) the above steps i) and ii). Hereinafter, it demonstrates in order of a process.
＜ｉ）水酸化アルミニウム含有水溶液の調製工程＞
調製方法としては、下記の（イ）及び（ロ）の方法が挙げられる。
（イ）先ずアルミニウム塩水溶液を調製し、このアルミニウム塩水溶液にアルカリ水溶液を添加して、中和反応により水酸化アルミニウムを生成させて水酸化アルミニウム含有水溶液を得る。
（ロ）先ずアルミニウム塩水溶液を調製し、このアルミニウム塩水溶液をアルカリ水溶液に添加して、中和反応により水酸化アルミニウムを生成させて水酸化アルミニウム含有水溶液を得る。
<I) Step of preparing aluminum hydroxide-containing aqueous solution>
Examples of the preparation method include the following methods (a) and (b).
(A) First, an aqueous aluminum salt solution is prepared, an aqueous alkaline solution is added to the aqueous aluminum salt solution, and aluminum hydroxide is produced by a neutralization reaction to obtain an aluminum hydroxide-containing aqueous solution.
(B) First, an aluminum salt aqueous solution is prepared, and this aluminum salt aqueous solution is added to an alkaline aqueous solution to produce aluminum hydroxide by a neutralization reaction to obtain an aluminum hydroxide-containing aqueous solution.
上記（イ）及び（ロ）の方法で用いるアルミニウム塩水溶液のアルミニウム塩としては、例えば、塩化物、硫酸塩、硝酸塩といった各種のアルミニウム塩を使用することができる。また、一種のアルミニウム塩を使用しても良く、又は数種のアルミニウム塩を混合して使用しても良い。該アルミニウム塩水溶液は、その濃度が好ましくは、０．０１〜３．６ｍｏｌ／Ｌ、より好ましくは０．１〜２．０ｍｏｌ／Ｌのものを使用する。 As the aluminum salt of the aluminum salt aqueous solution used in the above methods (a) and (b), for example, various aluminum salts such as chloride, sulfate and nitrate can be used. One kind of aluminum salt may be used, or several kinds of aluminum salts may be mixed and used. The concentration of the aluminum salt aqueous solution is preferably 0.01 to 3.6 mol / L, more preferably 0.1 to 2.0 mol / L.
上記（イ）及び（ロ）の方法で用いるアルカリ水溶液のアルカリとしては、例えば、ＮａＯＨ、ＫＯＨ、ＮＨ3 、Ｎａ2ＣＯ3、Ｋ2ＣＯ3、ＮａＨＣＯ3、ＫＨＣＯ3等を用いることができる。上記アルカリの量としては、水酸化アルミニウム含有水溶液のｐＨが１０．０〜１３．０、特に１０．５〜１２．５となる量であることが好ましい。上記ｐＨが１０．０未満では、粒子形態が針状、棒状、高アスペクト比の板状となり、また上記アルミニウム塩として硫酸塩を使用した場合に、球状、多角状のアルナイト［ＮａＡｌ3(ＳＯ4)2(ＯＨ）6］が生成する。上記ｐＨが１３．０より高い場合では、高アスペクト比、又は無定形の水酸化アルミニウムが溶解してアルミン酸ナトリウムとなる。 As the alkali of the alkaline aqueous solution used in the above methods (a) and (b), for example, NaOH, KOH, NH 3 , Na 2 CO 3 , K 2 CO 3 , NaHCO 3 , KHCO 3 or the like can be used. The amount of the alkali is preferably an amount such that the pH of the aluminum hydroxide-containing aqueous solution is 10.0 to 13.0, particularly 10.5 to 12.5. When the pH is less than 10.0, the particle form is needle-like, rod-like, or plate-shaped with a high aspect ratio. When sulfate is used as the aluminum salt, spherical and polygonal alunite [NaAl 3 (SO 4 ) 2 (OH) 6 ] is produced. When the pH is higher than 13.0, high aspect ratio or amorphous aluminum hydroxide is dissolved to form sodium aluminate.
本調製工程において、上述した有機化合物を添加する場合は、アルミニウム塩水溶液とアルカリ水溶液との中和反応により水酸化アルミニウムを生成させた後に添加しても良く、中和反応させる前のアルミニウム塩水溶液もしくはアルカリ水溶液に添加しておいても良く、アルミニウム塩水溶液にアルカリ水溶液を添加する際もしくはアルミニウム塩水溶液をアルカリ水溶液に添加する際に一緒に添加しても良い。
上記有機化合物の添加量は、ベーマイト微粒子表面又はアルミナ微粒子表面への被覆量を上述した好ましい範囲（炭素量換算で０．０１〜２．０重量％）とするために、ベーマイトの理論生成量に対して０．０１〜５．０重量％であることが好ましく、０．１〜３．０重量％であることがより好ましく、０．５〜１．０重量％であることがより一層好ましい。
In this preparation step, when the above-mentioned organic compound is added, it may be added after the formation of aluminum hydroxide by a neutralization reaction between an aluminum salt aqueous solution and an alkali aqueous solution, or an aluminum salt aqueous solution before the neutralization reaction. Alternatively, it may be added to an alkaline aqueous solution, or may be added together when adding an alkaline aqueous solution to an aluminum salt aqueous solution or when adding an aluminum salt aqueous solution to an alkaline aqueous solution.
The amount of the organic compound added is adjusted to the theoretical amount of boehmite so that the coating amount on the surface of the boehmite fine particles or the surface of the alumina fine particles is within the above-described preferred range (0.01 to 2.0% by weight in terms of carbon amount). On the other hand, it is preferably 0.01 to 5.0% by weight, more preferably 0.1 to 3.0% by weight, and still more preferably 0.5 to 1.0% by weight.
＜ii）水熱反応工程＞
上記水熱反応は、温度が２８０℃以上、好ましくは３００〜４００℃、且つ全圧力が好ましくは５．０ＭＰａ以上、より好ましくは５．０〜４０．０ＭＰａ、より一層好ましくは１０．０〜３０．０ＭＰａで、通常０．０１時間以上、好ましくは０．０１〜２４時間、より好ましくは０．０１〜８時間行うと良い。このような条件下で水熱反応させて、粒子径、粒子の厚さ、粒子の均一性等の粒子形態の制御を行い、濾過、水洗した後、乾燥することにより、本発明のベーマイト微粒子が得られる。
<Ii) Hydrothermal reaction process>
In the hydrothermal reaction, the temperature is 280 ° C. or higher, preferably 300 to 400 ° C., and the total pressure is preferably 5.0 MPa or higher, more preferably 5.0 to 40.0 MPa, still more preferably 10.0 to 30. It is good to carry out at 0.0 MPa, usually 0.01 hours or more, preferably 0.01 to 24 hours, more preferably 0.01 to 8 hours. Under such conditions, the boehmite fine particles of the present invention can be obtained by controlling the particle form such as particle diameter, particle thickness, particle uniformity, etc., filtering, washing with water and then drying. can get.
上記水熱反応条件は、水酸化アルミニウム含有水溶液における原料の種類、仕込み量、ｐＨ値、反応温度、反応圧力及び反応時間等によって上記範囲内において適宜決定すると良い。上記水熱反応の最低温度は２８０℃であることが好ましい。温度が２８０℃未満ではアスペクト比が３．０以下の板状であるベーマイト微粒子が得難い。また、最高温度には特に制限がなく、臨界点を超えても良いが、反応装置の仕様に制限される。
＜iii)ベーマイト微粒子の焼成工程＞
本焼成工程は、上記水熱反応工程で得られた本発明のベーマイト微粒子を焼成することにより本発明のアルミナ微粒子を得る工程である。
焼成は、大気雰囲気下（又は不活性ガス雰囲気下）、最高到達温度が通常５００〜１０００℃、好ましくは６００〜１０００℃で、通常０．５時間以上、好ましくは０．５〜８時間行うと良い。焼成温度が５００℃未満の場合では脱水反応が不十分であり、１０００℃より高温の場合では粒子間の焼結が生じ、粒子形態を維持することができない。ベーマイト微粒子の粒子表面に有機化合物が被覆されている場合では、粒子間の凝集及び焼結が起こらず、高温での熱処理を行っても粒子形態を維持できるという効果がある。
The hydrothermal reaction conditions may be appropriately determined within the above range depending on the type of raw material, the amount charged, the pH value, the reaction temperature, the reaction pressure, the reaction time, etc. in the aluminum hydroxide-containing aqueous solution. The minimum temperature of the hydrothermal reaction is preferably 280 ° C. When the temperature is less than 280 ° C., it is difficult to obtain boehmite fine particles having a plate shape with an aspect ratio of 3.0 or less. Moreover, there is no restriction | limiting in particular in maximum temperature, Although it may exceed a critical point, it is restrict | limited to the specification of a reactor.
<Iii) Baking process of boehmite fine particles>
The main baking step is a step of obtaining the alumina fine particles of the present invention by baking the boehmite fine particles of the present invention obtained in the hydrothermal reaction step.
Firing is performed in an air atmosphere (or in an inert gas atmosphere) at a maximum temperature of usually 500 to 1000 ° C., preferably 600 to 1000 ° C., usually 0.5 hours or more, preferably 0.5 to 8 hours. good. When the firing temperature is less than 500 ° C, the dehydration reaction is insufficient, and when the firing temperature is higher than 1000 ° C, sintering between particles occurs, and the particle morphology cannot be maintained. In the case where the surface of the boehmite fine particles is coated with an organic compound, there is an effect that aggregation and sintering between the particles do not occur, and the particle morphology can be maintained even when heat treatment is performed at a high temperature.
以下、実施例により本発明を説明するが、本発明はこれらの実施例に限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
（実施例１〜１７及び比較例１〜８）
［ベーマイト微粒子の製造］
アルミニウム塩水溶液として硫酸アルミニウム十六水和物水溶液（実施例１〜１４、比較例１〜８）又は硝酸アルミニウム九水和物水溶液（実施例１５〜１７）、アルカリ水溶液として水酸化ナトリウム水溶液、及び表１又は表２記載の有機化合物を用いて、表１又は表２記載のＡｌ量、アルカリ量、有機化合物添加量となるように原料を準備した。次に、アルミニウム塩水溶液に水酸化ナトリウム水溶液及び有機化合物を添加して、水酸化アルミニウム含有水溶液を調製した。調製後の水酸化アルミニウム含有水溶液のｐＨを表１及び表２に示す。
調製した水酸化アルミニウム含有水溶液をオートクレーブ中で攪拌しながら、表１又は表２記載の条件にて水熱反応を行った。反応終了後の反応液のｐＨを表１及び表２に示す。反応終了後、室温まで冷却を行い、生成物を濾過、水洗、乾燥して目的物であるベーマイト微粒子を得た。
(Examples 1-17 and Comparative Examples 1-8)
[Production of boehmite fine particles]
Aluminum sulfate hexadecahydrate aqueous solution (Examples 1-14, Comparative Examples 1-8) or aluminum nitrate nonahydrate aqueous solution (Examples 15-17) as an aqueous aluminum salt solution, sodium hydroxide aqueous solution as an alkaline aqueous solution, and Using the organic compounds described in Table 1 or Table 2, raw materials were prepared so that the amounts of Al, alkalis, and organic compounds added were as described in Table 1 or Table 2. Next, a sodium hydroxide aqueous solution and an organic compound were added to the aluminum salt aqueous solution to prepare an aluminum hydroxide-containing aqueous solution. Tables 1 and 2 show the pH of the prepared aluminum hydroxide-containing aqueous solution.
While the prepared aqueous solution containing aluminum hydroxide was stirred in an autoclave, a hydrothermal reaction was performed under the conditions described in Table 1 or Table 2. Tables 1 and 2 show the pH of the reaction solution after completion of the reaction. After completion of the reaction, the reaction mixture was cooled to room temperature, and the product was filtered, washed with water, and dried to obtain the desired boehmite fine particles.
得られたベーマイト微粒子について、Ｘ線回折、比表面積、炭素量（有機化合物被覆量）、粒子形状、平均粒子径、アスペクト比、粒度分布（メジアン径、変動係数）、分散性を以下の（１）〜（６）の方法により測定又は評価した。それらの結果を表３及び表４に示す。
また、実施例４で得られたベーマイト微粒子の電子顕微鏡写真（×60,000）を図１に、実施例５で得られたベーマイト微粒子の電子顕微鏡写真（×60,000）を図２にそれぞれ示す。実施例１〜１７で得られたベーマイト微粒子は何れも、粒子形態が均一であることが電子顕微鏡によって確認できた。また、比較例２で得られたベーマイト微粒子の電子顕微鏡写真（×60,000）を図３に、比較例４で得られたベーマイト微粒子の電子顕微鏡写真 (×120,000)を図４に、比較例５で得られたベーマイト微粒子の電子顕微鏡写真（×30,000）を図５にそれぞれ示す。
With respect to the obtained boehmite fine particles, X-ray diffraction, specific surface area, carbon amount (organic compound coating amount), particle shape, average particle diameter, aspect ratio, particle size distribution (median diameter, coefficient of variation), and dispersibility are as follows (1 ) To (6) for measurement or evaluation. The results are shown in Tables 3 and 4.
Further, an electron micrograph (× 60,000) of the boehmite fine particles obtained in Example 4 is shown in FIG. 1, and an electron micrograph (× 60,000) of the boehmite fine particles obtained in Example 5 is shown in FIG. It was confirmed with an electron microscope that the boehmite fine particles obtained in Examples 1 to 17 had a uniform particle form. Also, an electron micrograph (× 60,000) of the boehmite fine particles obtained in Comparative Example 2 is shown in FIG. 3, an electron micrograph (× 120,000) of the boehmite fine particles obtained in Comparative Example 4 is shown in FIG. FIG. 5 shows electron micrographs (× 30,000) of the obtained boehmite fine particles.
（１）Ｘ線回折
理学電機社製Ｘ線回折装置(RINT-2200V)にて測定した。
（２）比表面積
マウンテック社製全自動ＢＥＴ比表面積測定装置(Macsorb HM Model-1210) にて測定した。
（３）炭素量（有機化合物被覆量の評価）
堀場製作所製炭素分析装置(EMIA-221V) にて測定し、ベーマイト微粒子の表面に被覆されている有機化合物を炭素量として定量した。
（４）平均粒子径とアスペクト比の測定、及び粒子形状の評価
日立製作所製透過型電子顕微鏡(TEM H-7600) を用いて、２００個以上の粒子径を計測し、その平均値を求めた。また、アスペクト比は、平均粒子径と同様に粒子の厚さの平均値を求め、［平均粒子径／粒子の厚さ］から算出した。
（５）粒度分布（メジアン径、変動係数）
ベーマイト微粒子５〜１０ｍｇを０．２重量％のヘキサメタリン酸ナトリウム水溶液３０ｍｌに添加し、ホモジナイザにより分散させた（３６０Ｗにて３０秒間) 。その分散液を堀場製作所製レーザー回折／散乱式粒子径分布測定装置（LA-950）にて測定し、体積基準のメジアン径とその変動係数を求めた。
（６）分散性評価
粒度分布測定で用いた分散液を静置し、凝集、沈降粒子の状態を観察することにより、分散性を評価した（分散液が安定に分散している場合を○、凝集、沈降した場合を×とした）。
(1) X-ray diffraction Measured with an X-ray diffractometer (RINT-2200V) manufactured by Rigaku Corporation.
(2) Specific surface area Measured with a fully automatic BET specific surface area measuring device (Macsorb HM Model-1210) manufactured by Mountec.
(3) Carbon content (evaluation of organic compound coverage)
Measurement was performed with a carbon analyzer (EMIA-221V) manufactured by HORIBA, Ltd., and the organic compound coated on the surface of the boehmite fine particles was quantified as the amount of carbon.
(4) Measurement of average particle diameter and aspect ratio, and evaluation of particle shape Using a Hitachi transmission electron microscope (TEM H-7600), 200 or more particle diameters were measured, and the average value was obtained. . Further, the aspect ratio was calculated from [average particle diameter / particle thickness] by obtaining the average value of the particle thickness in the same manner as the average particle diameter.
(5) Particle size distribution (median diameter, coefficient of variation)
5 to 10 mg of boehmite fine particles were added to 30 ml of a 0.2 wt% sodium hexametaphosphate aqueous solution and dispersed with a homogenizer (at 360 W for 30 seconds). The dispersion was measured with a laser diffraction / scattering particle size distribution analyzer (LA-950) manufactured by Horiba, Ltd., and the volume-based median diameter and its coefficient of variation were determined.
(6) Dispersibility evaluation The dispersion used in the particle size distribution measurement was allowed to stand, and the dispersibility was evaluated by observing the state of agglomeration and sedimentation particles (when the dispersion is stably dispersed, The case of aggregation and sedimentation was marked with x).
（実施例１８〜２５及び比較例９〜１１）
［アルミナ微粒子の製造］
実施例１８〜２０及び２２においては実施例２で得られたベーマイト微粒子を、実施例２１及び２３並びに比較例９〜１１においては実施例５で得られたベーマイト微粒子を、実施例２４においては実施例１１で得られたベーマイト微粒子を、実施例２５においては実施例１３で得られたベーマイト微粒子を、それぞれ大気下において表５記載の条件にて焼成して目的物であるアルミナ微粒子を得た。
得られたアルミナ微粒子について、Ｘ線回折、比表面積、炭素量（有機化合物被覆量）、粒子形状、平均粒子径、アスペクト比、粒度分布（メジアン径、変動係数）、分散性を上記と同様の方法により測定又は評価した。それらの結果を表５に示す。また、実施例２４で得られたアルミナ微粒子の電子顕微鏡写真（×60,000）を図６に示す。
(Examples 18 to 25 and Comparative Examples 9 to 11)
[Production of alumina fine particles]
In Examples 18 to 20 and 22, the boehmite fine particles obtained in Example 2 were used. In Examples 21 and 23 and Comparative Examples 9 to 11, the boehmite fine particles obtained in Example 5 were used. The boehmite fine particles obtained in Example 11 and the boehmite fine particles obtained in Example 13 in Example 25 were calcined under the conditions described in Table 5 in the air, respectively, to obtain alumina fine particles as the target product.
About the obtained alumina fine particles, X-ray diffraction, specific surface area, carbon amount (organic compound coating amount), particle shape, average particle diameter, aspect ratio, particle size distribution (median diameter, coefficient of variation), dispersibility are the same as above. Measured or evaluated by the method. The results are shown in Table 5. In addition, an electron micrograph (× 60,000) of the alumina fine particles obtained in Example 24 is shown in FIG.
実施例１〜１７の結果より、本発明のベーマイト微粒子は、水熱反応温度、ｐＨ調整、有機化合物添加量によって粒子形状、粒子径を制御できることがわかる。また、粒子の均一性、分散性に優れる。アスペクト比３．０以下の板状粒子を得るには、実施例１より水熱反応温度が２８０℃以上必要である。比較例２及び４の結果より、水熱反応温度が２８０℃未満の場合ではアスペクト比が高くなり、凝集により分散性が悪い。また、有機化合物の添加は、均一化、微粒子化に効果がある。比較例１及び５〜８の結果より、水酸化アルミニウム含有水溶液のｐＨが１０未満であると粒子形状が高アスペクト比の針状、棒状となり、更に酸性になると球状、多角状のアルナイトが生成する。また、比較例３の結果より、水酸化アルミニウム含有水溶液のｐＨが１４では水酸化アルミニウムが溶解してアルミン酸ナトリウムとなり粒子が生成しない。 From the results of Examples 1 to 17, it can be seen that the boehmite fine particles of the present invention can control the particle shape and particle diameter by the hydrothermal reaction temperature, pH adjustment, and the amount of organic compound added. In addition, the uniformity and dispersibility of the particles are excellent. In order to obtain plate-like particles having an aspect ratio of 3.0 or less, a hydrothermal reaction temperature of 280 ° C. or higher is required from Example 1. From the results of Comparative Examples 2 and 4, when the hydrothermal reaction temperature is less than 280 ° C., the aspect ratio is high, and the dispersibility is poor due to aggregation. Addition of an organic compound is effective for homogenization and fine particle formation. From the results of Comparative Examples 1 and 5-8, when the pH of the aluminum hydroxide-containing aqueous solution is less than 10, the shape of the particles becomes high-aspect-ratio needles and rods, and when it becomes acidic, spherical and polygonal alunite is generated. . From the results of Comparative Example 3, when the pH of the aluminum hydroxide-containing aqueous solution is 14, the aluminum hydroxide is dissolved and becomes sodium aluminate, and particles are not generated.
実施例１８及び１９の結果より、本発明のアルミナ微粒子は、焼成温度が５００℃以上では、脱水によりベーマイトからアルミナとなる。また、実施例１９〜２５の結果より、焼成すると板状のベーマイト粒子の角がとれて丸くなる。例えば板状の表面が正方形のベーマイト粒子が、角がとれて多角形の板状のベーマイト粒子となる。比較例９〜１１の結果より、焼成温度が１１００℃以上では粒子の焼結により不定形の粒子が生じる。また、凝集により粒度分布のメジアン径、変動係数が増大する。 From the results of Examples 18 and 19, the alumina fine particles of the present invention are converted from boehmite to alumina by dehydration at a firing temperature of 500 ° C. or higher. Moreover, from the results of Examples 19 to 25, when fired, the corners of the plate-like boehmite particles are removed and rounded. For example, square boehmite particles having a plate-like surface are rounded to form polygonal plate-like boehmite particles. From the results of Comparative Examples 9 to 11, when the firing temperature is 1100 ° C. or higher, particles having irregular shapes are generated by the sintering of the particles. In addition, the median diameter and coefficient of variation of the particle size distribution increase due to aggregation.
本発明は、粒子形態が微細で均一であり、凝集がなく分散性に優れたアルミナ微粒子及びその製造方法に関する。本発明のアルミナ微粒子は、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等の材料として好適に使用することができる。
The present invention is uniform in particulate form is fine, the alumina particles and a manufacturing method thereof relating to aggregation was excellent without dispersibility. Alumina fine particles of the present invention, particles abrasives, toner external additive particles, paint pigments, rubber and plastics filler, ceramic raw material such as translucent material, IC substrate, AlN precursor, adsorbents, catalyst It can be suitably used as a material such as a carrier.
本発明は、上記のような事情に鑑みなされたものであり、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等の様々な用途に適した、粒子形態が微細で均一であり、凝集がなく分散性に優れたアルミナ微粒子及びその製造方法を提供することを目的とする。
The present invention has been made in view of the above circumstances, abrasive particles, particles for external toner additives, paint pigments, rubber and plastic fillers, ceramic raw materials such as translucent materials and IC substrates, AlN precursor, adsorbent, suitable for various applications, such as catalyst support, is uniform in particulate form fine, and aims to provide an excellent alumina fine particles, and a method of manufacturing the same dispersion without agglomeration To do.
本発明者らは、上記課題を解決すべく鋭意検討を進めた結果、水熱反応時の水酸化アルミニウム含有水溶液において、アルミニウム（以下、Ａｌとも表記する）、アルカリ及び有機化合物の含有量を特定量とすることにより得られる、特定の平均粒子径、及び特定の有機化合物被覆量を有するアルミナ微粒子が、粒子径の制御が可能であり、凝集がなく分散性に優れ、粒子形態が均一であり、特に研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等として使用する場合、粒子の微粒子化、均一性、高分散性等の該用途に要求される性能を有することを見出し、本発明を完成させた。
As a result of intensive studies to solve the above problems, the present inventors have specified the contents of aluminum (hereinafter also referred to as Al), alkali and organic compounds in the aluminum hydroxide-containing aqueous solution during the hydrothermal reaction. obtained by the amount, specific average particle diameter and a specific Rua alumina particles having a organic compound coverage is possible to control the particle size, good dispersibility without agglomeration, the particle form Uniform, especially as abrasive particles, toner additive particles, paint pigments, rubber and plastic fillers, ceramic materials such as translucent materials and IC substrates, precursors for AlN, adsorbents, catalyst carriers, etc. When used, it has been found that it has performances required for such applications such as fine particle formation, uniformity and high dispersibility, and the present invention has been completed.
即ち、本発明は、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ2／ｇ、アスペクト比が３．０以下の板状であるアルミナ微粒子、好ましくは、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ2／ｇ、アスペクト比が３．０以下の板状であって、炭素量が０．０１〜２．０重量％であるアルミナ微粒子を提供するものである。
That is , in the present invention, the median diameter of the particle size distribution is 0.05 to 1.0 μm, the coefficient of variation of the particle size distribution is 45.0% or less, the specific surface area is 1.0 to 150.0 m 2 / g, and the aspect ratio is 3 0.0 or less plate-like alumina fine particles, preferably the median diameter of the particle size distribution is 0.05 to 1.0 μm, the coefficient of variation of the particle size distribution is 45.0% or less, and the specific surface area is 1.0 to 150.0 m. The present invention provides an alumina fine particle having a plate shape of 2 / g and an aspect ratio of 3.0 or less and having a carbon content of 0.01 to 2.0% by weight.
また、本発明は、上記の本発明のアルミナ微粒子を製造するための好ましい製造方法として、粒度分布のメジアン径が０．０５〜１．０μｍ、粒度分布の変動係数が４５．０％以下、比表面積が１．０〜１５０．０ｍ 2 ／ｇ、アスペクト比が３．０以下の板状であるベーマイト微粒子を、５００〜１０００℃で焼成することを特徴とするアルミナ微粒子の製造方法を提供するものである。
Also, the present invention provides a preferred method for preparing the alumina particles of the invention described above, the median diameter of particle size distribution 0.05 to 1.0 [mu] m, variation coefficient of the particle size distribution 45.0% or less, Provided is a method for producing alumina fine particles, characterized in that plate-like boehmite fine particles having a specific surface area of 1.0 to 150.0 m 2 / g and an aspect ratio of 3.0 or less are fired at 500 to 1000 ° C. Is.
本発明のアルミナ微粒子は、従来のアルミナ粒子の課題であった粒子の微粒子化、均一化、高分散性を同時に実現しているため、例えば、研磨剤用粒子、トナー外添剤用粒子、塗料用顔料、ゴム・プラスチック用フィラー、透光材料・ＩＣ基板等のセラミックス原料、ＡｌＮ用前駆体、吸着剤、触媒担体等の材料として好適である。
Alumina fine particles of the present invention, fine particles of problems in a particle of a conventional Alumina particles uniform, because it realizes highly dispersible simultaneously, for example, particles abrasives, toner external additive particles It is suitable as a material for coating pigments, rubber / plastic fillers, ceramic raw materials such as translucent materials and IC substrates, AlN precursors, adsorbents, catalyst carriers and the like.
以下、本発明のアルミナ微粒子及びその製造方法について好ましい実施形態に基づき記述するが、本発明はこれらの記載に限定されるものではない。尚、以下の「本発明のベーマイト微粒子」は参考例である。
Hereinafter referred on the basis of preferred embodiments for the alumina particles and the manufacturing method thereof of the present invention, the present invention is not limited to these descriptions. The following “Boehmite fine particles of the present invention” are reference examples.
以下、実施例により本発明を説明するが、本発明はこれらの実施例に限定されるものではない。尚、実施例１〜１７及び比較例１〜８（ベーマイト微粒子に関する実施例及び比較例）は参考例である。 EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. Examples 1 to 17 and Comparative Examples 1 to 8 (Examples and Comparative Examples relating to boehmite fine particles) are reference examples.
Claims (13)
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| EP3770685A1 (en) * | 2019-07-25 | 2021-01-27 | Ricoh Company, Ltd. | Toner, toner accommodating container, developer, developing device, process cartridge, image forming apparatus, and image forming method |
| JP2022504289A (en) * | 2018-10-03 | 2022-01-13 | サソール（ユーエスエイ）コーポレーシヨン | Alumina and its manufacturing method |
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| EP3770685A1 (en) * | 2019-07-25 | 2021-01-27 | Ricoh Company, Ltd. | Toner, toner accommodating container, developer, developing device, process cartridge, image forming apparatus, and image forming method |
| US11281118B2 (en) | 2019-07-25 | 2022-03-22 | Ricoh Company, Ltd. | Toner, toner accommodating container, developer, developing device, process cartridge, image forming apparatus, and image forming method |
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