JP3035607B2 - Highly plasticized alumina particles coated with alumina hydrate and method for producing the same - Google Patents
Highly plasticized alumina particles coated with alumina hydrate and method for producing the sameInfo
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- JP3035607B2 JP3035607B2 JP10169870A JP16987098A JP3035607B2 JP 3035607 B2 JP3035607 B2 JP 3035607B2 JP 10169870 A JP10169870 A JP 10169870A JP 16987098 A JP16987098 A JP 16987098A JP 3035607 B2 JP3035607 B2 JP 3035607B2
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- alumina
- alumina particles
- producing
- plasticity
- slurry
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- Compositions Of Oxide Ceramics (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、高い可塑性を保有
するアルミナ粒子及びその製造方法に関するもので、セ
ラミックス用成形材料として好適なアルミナ粒子に関す
る。特に水系での成形においてバインダー等の不純物を
添加せずに練土とすることができ、そのため成形及び焼
成の工程を短縮することができる。The present invention relates to alumina particles having high plasticity and a method for producing the same, and more particularly to alumina particles suitable as a molding material for ceramics. In particular, in the case of molding in an aqueous system, the clay can be formed without adding impurities such as a binder, so that the steps of molding and firing can be shortened.
【０００２】[0002]
【従来の技術】α−アルミナはセラミックス原料として
広く活用されている。そのα−アルミナの製造方法はバ
イヤー法などで製造されており、従来アルミナ原料とし
て製造されているのはα−アルミナ単相である。しか
し、粘土と比較してα−アルミナの可塑性は乏しいこと
が水田、芝崎、酒井、片桐、藤本、；粉末および粉末冶
金、３５巻、７号（１９８８）、６１９頁などで指摘さ
れている。2. Description of the Related Art α-alumina is widely used as a raw material for ceramics. The α-alumina is produced by a Bayer method or the like, and the α-alumina single phase is conventionally produced as an alumina raw material. However, it is pointed out that the plasticity of α-alumina is poorer than that of clay in rice fields, Shibazaki, Sakai, Katagiri, Fujimoto; Powder and Powder Metallurgy, Vol. 35, No. 7, (1988), p. 619.
【０００３】そのためアルミナセラミックスを、押出し
成形や射出成形などの可塑成形で作る場合は、成形助剤
として有機物を添加する必要がある。しかし、有機物を
添加することにより作業性が悪化したり、焼結時には成
形助剤中の不純物や分解しきれないカーボンが影響し、
緻密なアルミナセラミックスを作ることが困難である等
の不具合が生じる。Therefore, when alumina ceramics are produced by plastic molding such as extrusion molding or injection molding, it is necessary to add an organic substance as a molding aid. However, the workability deteriorates due to the addition of organic substances, and impurities and carbon that cannot be completely decomposed in the molding aid during sintering affect
Problems such as difficulty in producing dense alumina ceramics occur.
【０００４】そこで成形助剤を使用しなくても容易に可
塑成形ができる可塑性の良いアルミナ粉体が切望されて
いる。[0004] Therefore, highly plastic alumina powder which can be easily plasticized without using a molding aid has been desired.
【０００５】可塑性には粒子が板状形態であることが有
利なことが知られている。しかし、板状形態を持つアル
ミナを用いても粘土と比較すると可塑性に乏しい。[0005] It is known that for plasticity it is advantageous for the particles to be in plate-like form. However, even if alumina having a plate shape is used, the plasticity is poor compared to clay.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、セラ
ミックス原料として可塑性に富むアルミナ粒子及びその
製造法を提供することにある。特には板状アルミナの可
塑性をさらに向上させることにある。SUMMARY OF THE INVENTION An object of the present invention is to provide highly plastic alumina particles as a ceramic raw material and a method for producing the same. In particular, it is to further improve the plasticity of plate-like alumina.
【０００７】[0007]
【課題を解決するための手段】本発明者らは鋭意検討し
た結果、アルミナ粒子の表面にアルミナ水和物を析出さ
せることにより表面積を増大させ、凝集力を大きくする
ことにより上記課題が解決されることを見出し本発明に
至った。Means for Solving the Problems As a result of intensive studies, the present inventors have solved the above-mentioned problems by increasing the surface area by precipitating alumina hydrate on the surface of alumina particles and increasing the cohesive force. This led to the present invention.
【０００８】すなわち、本発明は次の（１）〜（３）で
ある。That is, the present invention provides the following (1) to ( 3 ).
【０００９】[0009]
【００１０】[0010]
【００１１】[0011]
【００１２】[0012]
【００１３】（１）アルミナ粒子をアルミニウム塩水溶
液中に混合し、これを中和することにより被覆層を得る
ことを特徴とする高可塑性アルミナ粒子の製造方法であ
って、アルミナ水和物のアルミナに対する含有量が５〜
５０重量％であることを特徴とする高可塑性アルミナ粒
子の製造方法。( 1 ) A method for producing highly plastic alumina particles, characterized in that alumina particles are mixed in an aqueous solution of aluminum salt and neutralized to obtain a coating layer. 5 to 5
A method for producing highly plastic alumina particles, which is 50% by weight.
【００１４】[0014]
【００１５】（２）アルミナ水和物を含むアルミナ粒子
に熱処理を施すことを特徴とする前記（１）記載の高可
塑性アルミナの製造方法。( 2 ) The method for producing highly plastic alumina according to ( 1 ), wherein the alumina particles containing alumina hydrate are subjected to a heat treatment.
【００１６】（３）熱処理の温度が３００〜７００℃で
あることを特徴とする前記（２）記載の高可塑性アルミ
ナの製造方法。( 3 ) The method for producing a highly plasticized alumina according to the above ( 2 ), wherein the temperature of the heat treatment is 300 to 700 ° C.
【００１７】本発明のアルミナ粒子は、アルミナ粒子の
表面にアルミナ水和物を被覆したものである。本発明に
おいてアルミナ粒子は球状、板状、棒状などの形状は問
わない。この中で板状α−アルミナ粒子が好ましい。用
いるアルミニウム塩は特に限定されないが、硫黄塩や硝
酸塩が好ましい。また、これらの中和法も特に限定され
ない。アルミニウム塩水溶液中にアルミナ粒子を分散さ
せたスラリーを撹拌しながら、これに適度な速度でアル
カリ水溶液を滴下し１〜５０時間程度かけてｐＨを中性
域とし滴下を終了する。用いるアルカリ水溶液は特に限
定されないが、水酸化ナトリウムやアンモニウア水溶液
が好ましい。また、先のスラリー中に尿素を混合し、そ
の加熱加水分解により生じるアンモニアにより中和しｐ
Ｈを中性とし被覆操作を完了させることも可能である。The alumina particles of the present invention are obtained by coating the surfaces of alumina particles with alumina hydrate. In the present invention, the shape of the alumina particles such as a sphere, a plate, and a bar is not limited. Of these, plate-like α-alumina particles are preferred. The aluminum salt used is not particularly limited, but a sulfur salt or a nitrate is preferred. In addition, these neutralization methods are not particularly limited. While stirring the slurry in which the alumina particles are dispersed in the aluminum salt aqueous solution, an alkaline aqueous solution is dropped at an appropriate speed, the pH is set to a neutral range over about 1 to 50 hours, and the dropping is completed. The alkaline aqueous solution to be used is not particularly limited, but sodium hydroxide or an ammonium aqueous solution is preferable. Also, urea is mixed into the above slurry, neutralized with ammonia generated by its thermal hydrolysis, and p
It is also possible to make H neutral and complete the coating operation.
【００１８】上記のように、アルミナ粒子の形状は特に
問わないが、その中で微細な六角板状であることにより
水で練ると可塑性が強く発現する。その粒子の大きさと
しては１５μｍ以下で厚さが１μｍ以下であることが有
効である。特には大きさは２．０μｍ以下、厚さは０．
１μｍ以下であることが好ましい。As described above, although the shape of the alumina particles is not particularly limited, plasticity is strongly exhibited when kneaded with water because of the fine hexagonal plate shape. It is effective that the particles have a size of 15 μm or less and a thickness of 1 μm or less. In particular, the size is 2.0 μm or less, and the thickness is 0.1 μm.
It is preferably 1 μm or less.
【００１９】本発明の高可塑性アルミナ粒子の製造法は
以下のとおりである。The method for producing the highly plastic alumina particles of the present invention is as follows.
【００２０】純水に可溶のアルミニウム塩（硫酸アルミ
ニウム、硝酸アルミニウム等）を溶解し、その中にアル
ミナ粒子を混合後良く撹拌しスラリーとする。このスラ
リーの撹拌下にアルカリ水溶液をゆっくり滴下しスラリ
ーのｐＨが７程度となったら滴下を終了する。または、
アルミナスラリー中に尿素を溶解させ、このスラリーを
撹拌しながら７０〜９５℃程度に加熱し尿素を加水分解
させることによりアンモニアを発生させ、これによりス
ラリーを中和させる。この方法においてもｐＨ７を反応
の終点とし、この時点で加熱をやめ撹拌しながら放冷す
る。反応温度は７０℃以下では尿素の加水分解が進まな
いためこれ以上の温度が必要であり、また、温度により
加水分解速度が調節でき、９５℃以下の範囲において好
適な加水分解速度が得られる。An aluminum salt (aluminum sulfate, aluminum nitrate, etc.) soluble in pure water is dissolved, and alumina particles are mixed therein and stirred well to form a slurry. While the slurry is being stirred, the aqueous alkali solution is slowly dropped, and when the pH of the slurry reaches about 7, the dropping is completed. Or
Urea is dissolved in the alumina slurry, and the slurry is heated to about 70 to 95 ° C. with stirring to hydrolyze the urea to generate ammonia, thereby neutralizing the slurry. In this method as well, pH 7 is used as the end point of the reaction, at which point heating is stopped and the mixture is allowed to cool with stirring. If the reaction temperature is 70 ° C. or lower, the hydrolysis of urea does not proceed, so a higher temperature is required. Further, the hydrolysis rate can be adjusted by the temperature, and a suitable hydrolysis rate can be obtained in the range of 95 ° C. or lower.
【００２１】被覆処理後のスラリーを遠心分離により固
液分離を行い、固体分は純水を用いて良く洗浄し乾燥さ
せる。これを粉砕後１００メッシュの篩にかけた後か焼
し、高可塑性アルミナ粒子を得る。このようにして得ら
れたアルミナ粒子は内部がアルミナで、その表面にアル
ミナ水和物が被覆したものとなる。The slurry after the coating treatment is subjected to solid-liquid separation by centrifugation, and the solid is thoroughly washed with pure water and dried. This is pulverized, passed through a 100-mesh sieve, and calcined to obtain highly plastic alumina particles. The alumina particles thus obtained have alumina inside, and their surfaces are coated with alumina hydrate.
【００２２】アルミナ水和物のアルミナに対する含有量
は５〜５０重量％であることが好ましく、これ以下であ
ると本発明の目的である高可塑性を有するための被覆層
が得られない。The content of the alumina hydrate with respect to the alumina is preferably from 5 to 50% by weight, and if it is less than this, a coating layer having high plasticity, which is the object of the present invention, cannot be obtained.
【００２３】アルミニウム塩のアルカリによる中和は、
１〜７０時間程度で行えるが２４〜５０時間程度が好適
である。これは中和速度が速いと中和により析出するア
ルミナ水和物粒子がアルミナ粒子に付着せずに単離し、
これが核となり成長することによりアルミナ粒子上に必
要な膜厚を得ることができないためである。また、加水
分解速度は遅い程良いが５０時間以上では効果が変わら
ず、工業的に考えると不適である。The neutralization of an aluminum salt with an alkali is
Although it can be performed in about 1 to 70 hours, about 24 to 50 hours is preferable. This is because if the neutralization rate is high, alumina hydrate particles precipitated by neutralization are isolated without attaching to the alumina particles,
This is because a required film thickness cannot be obtained on the alumina particles due to growth as a nucleus. The slower the hydrolysis rate, the better, but the effect does not change after 50 hours or more, which is unsuitable from an industrial point of view.
【００２４】表面被覆後のアルミナ粒子をか焼するのは
高い表面積を得るためであり、３００℃以下では表面積
の増加が少ないため不適であり、７００℃以上では粒子
同士の焼結が激しいため可塑性が乏しくなり不適であ
る。The reason for calcining the alumina particles after the surface coating is to obtain a high surface area. At a temperature of 300 ° C. or less, the increase in the surface area is small, which is unsuitable. Is poor and unsuitable.
【００２５】このように、本発明の高可塑性アルミナ粒
子は、その表面にのみアルミナ水和物を持つ構造が特徴
である。この処理により粒子の大きさ、形はほとんど変
わることなく、表面積が大きくなる、これにより凝集し
やすくなり可塑性が向上する。As described above, the highly plastic alumina particles of the present invention are characterized by a structure having alumina hydrate only on the surface thereof. This treatment hardly changes the size and shape of the particles and increases the surface area. This facilitates agglomeration and improves plasticity.
【００２６】また、本発明の方法においては硫酸根等の
わずかなイオンは不純物として混入してしまうが、中和
にアンモニアを用いるとナトリウム等の異常粒成長の原
因となるイオンは混入せず、セラミックス原料として好
ましい。In the method of the present invention, slight ions such as sulfate groups are mixed as impurities. However, when ammonia is used for neutralization, ions such as sodium which cause abnormal grain growth are not mixed. It is preferable as a ceramic raw material.
【００２７】[0027]
【００２８】[0028]
【実施例】以下、実施例を用いて本発明を更に詳しく説
明する。The present invention will be described in more detail with reference to the following examples.
【００２９】アルミナ粒子としては、特開平５−１７１
３２、特開平６−３１６４１３等に示す水熱合成による
板状α−アルミナ粒子を原料とした。As the alumina particles, JP-A-5-171
32, plate-like α-alumina particles obtained by hydrothermal synthesis shown in JP-A-6-316413 and the like were used as raw materials.
【００３０】可塑性の評価は、万能試験機を用いた圧縮
試験により行った。この評価は、練土の可塑性評価法と
して知られているペッファーコーン試験と同じ傾向を示
している。また、圧縮という実際の成形法に近い操作で
評価できるためこの方法を用いた。評価法の概略を図に
示す。図１の圧縮試験から求められる変位−荷重曲線よ
り図２の変位−応力曲線を求め、この初期立ち上がりの
傾きを保形性の指標、変位−荷重曲線の後半部の積分値
を図３に示す流動性の指標（変形比０．６５〜０．８３
の範囲の仕事量を流動性の指標）として評価を行ってい
る。The plasticity was evaluated by a compression test using a universal testing machine. This evaluation shows the same tendency as the Peffer cone test which is known as a method for evaluating the plasticity of the clay. This method was used because it can be evaluated by an operation similar to the actual molding method of compression. The figure shows an outline of the evaluation method. The displacement-stress curve shown in FIG. 2 is obtained from the displacement-load curve obtained from the compression test shown in FIG. 1, and the slope of the initial rise is shown as an index of shape retention, and the integral value of the latter half of the displacement-load curve is shown in FIG. Index of fluidity (deformation ratio 0.65 to 0.83
Is evaluated using the amount of work within the range as an index of liquidity).
【００３１】保形性が高く、流動性が良いものが可塑性
がよいとしており、すなわち図３の傾きが緩いほど可塑
性が良いという評価である。この評価には直径３３ミリ
高さ４０ミリの試験片を用いている。A sample having high shape retention and good fluidity is considered to have good plasticity, that is, the graded in FIG. For this evaluation, a test piece having a diameter of 33 mm and a height of 40 mm was used.
【００３２】実施例１ 純水１０００ｇをスターラーで撹拌し、この中に中心粒
径０．６μｍ比表面積８ｍ2／ｇの板状α−アルミナ粒
子８５ｇと硫酸アルミニウム１６水和物７０ｇを加え良
く分散させ、これに０．０１規定のアンモニウム水溶液
を１分当たり１ｍｌの速度でｐＨ７となるまで滴下し
た。このスラリーを固液分離し純水で洗浄することによ
り反応副生成物を除去した後、１０５℃で乾燥し１００
メッシュの篩を通した後５００℃でか焼し、高可塑性α
−アルミナ粒子を得た。可塑性の評価は上記圧縮試験に
て行った。可塑性評価結果を図４に示す。Example 1 1000 g of pure water was stirred with a stirrer, and 85 g of plate-like α-alumina particles having a center particle diameter of 0.6 μm and a specific surface area of 8 m 2 / g and 70 g of aluminum sulfate hexahydrate were added thereto and dispersed well. Then, a 0.01 N aqueous ammonium solution was added dropwise at a rate of 1 ml per minute until the pH reached 7. The slurry was separated into solid and liquid and washed with pure water to remove reaction by-products.
After passing through a mesh sieve, calcined at 500 ° C.
-Alumina particles were obtained. Evaluation of plasticity was performed by the above-mentioned compression test. FIG. 4 shows the plasticity evaluation results.
【００３３】実施例２ 純水１０００ｇをスターラーで撹拌し、この中に中心粒
径０．６μｍ比表面積８ｍ2／ｇの板状α−アルミナ粒
子８５ｇと硫酸アルミニウム１６水和物７０ｇ、尿素１
６０ｇを加え良く分散させ、７０℃の恒温槽中でスラリ
ーｐＨが７となるまで反応させた。このスラリーを固液
分離し純水で洗浄することにより反応副生成物を除去し
た後、１０５℃で乾燥し１００メッシュの篩を通した後
５００℃でか焼し、高可塑性α−アルミナ粒子を得た。
可塑性評価結果を図４に示す。Example 2 1000 g of pure water was stirred with a stirrer, and 85 g of plate-like α-alumina particles having a center particle diameter of 0.6 μm and a specific surface area of 8 m 2 / g, 70 g of aluminum sulfate hexahydrate, and urea 1
60 g was added and dispersed well, and the mixture was reacted in a constant temperature bath at 70 ° C. until the slurry pH reached 7. After removing the reaction by-products by solid-liquid separation of this slurry and washing with pure water, the slurry was dried at 105 ° C., passed through a 100-mesh sieve, and calcined at 500 ° C. to obtain highly plastic α-alumina particles. Obtained.
FIG. 4 shows the plasticity evaluation results.
【００３４】実施例３ 純水１０００ｇをスターラーで撹拌し、この中に中心粒
径０．６μｍ比表面積８ｍ2／ｇの板状α−アルミナ粒
子８５ｇと硫酸アルミニウム１６水和物２０ｇ、尿素８
０ｇを加え良く分散させ、７０℃の恒温槽中でスラリー
ｐＨが７となるまで反応させた。このスラリーを固液分
離し純水で洗浄することにより反応副生成物を除去した
後、１０５℃で乾燥し１００メッシュの篩を通した後５
００℃でか焼し、高可塑性α−アルミナ粒子を得た。可
塑性評価結果を図４に示す。Example 3 1000 g of pure water was stirred with a stirrer, and 85 g of plate-like α-alumina particles having a center particle diameter of 0.6 μm and a specific surface area of 8 m 2 / g, 20 g of aluminum sulfate hexahydrate, and urea 8
0 g was added and dispersed well, and the mixture was reacted in a constant temperature bath at 70 ° C. until the slurry pH reached 7. The slurry was solid-liquid separated and washed with pure water to remove reaction by-products. The slurry was dried at 105 ° C. and passed through a 100-mesh sieve.
Calcination at 00 ° C. gave highly plastic α-alumina particles. FIG. 4 shows the plasticity evaluation results.
【００３５】[0035]
【発明の効果】本発明によれば、高可塑性を有するアル
ミナ質材料が得られ、緻密で密度の高い成形体を得るこ
とができる。従って、構造用部品、電子部品その他の分
野に耐熱性、電気絶縁性、機械的強度等の優れた材料と
して広く応用することができる。According to the present invention, an alumina-based material having high plasticity can be obtained, and a compact having a high density can be obtained. Therefore, it can be widely applied to structural components, electronic components, and other fields as materials having excellent heat resistance, electrical insulation, mechanical strength, and the like.
【図１】練土の荷重と変位の関係を示すグラフ。FIG. 1 is a graph showing a relationship between a load and displacement of a clay.
【図２】練土の歪みと応力との関係を示すグラフ。FIG. 2 is a graph showing a relationship between strain and stress of the clay.
【図３】練土の保形性と流動性との関係を示すグラフ。FIG. 3 is a graph showing the relationship between shape retention and fluidity of the clay.
【図４】練土の可塑性の評価の結果を示すグラフ。FIG. 4 is a graph showing the results of evaluation of plasticity of a clay.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 佐野 三郎 愛知県名古屋市千種区北千種３−２− ３，15−24 (72)発明者 伴野 巧 愛知県名古屋市北区八千代町２−109, 八千代寮103 (72)発明者 小栗 賢太 愛知県名古屋市東区砂田橋３−２，103 −1206 (72)発明者 川合 秀治 愛知県半田市瑞穂町２−３−22，イース トタウン206号室 (72)発明者 野村 祐二 愛知県名古屋市北区金城２−１−11，コ ーポ若園Ｅ号 (56)参考文献 特開 昭59−83931（ＪＰ，Ａ) 特開 平５−17132（ＪＰ，Ａ) 特開 平６−316413（ＪＰ，Ａ) 特開 平７−331110（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C01F 7/02 C04B 35/10 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Saburo Sano 3-2-3, 15-24 Kita Chikusa, Chikusa-ku, Nagoya, Aichi Prefecture (72) Inventor Takumi 2-109, Yachiyo-cho, Kita-ku, Nagoya, Aichi Prefecture Yachiyo Dormitory 103 (72) Inventor Kenta Oguri 3-2, 103-1206, Sunadabashi, Higashi-ku, Nagoya-shi, Aichi (72) Inventor Shuji Kawai 2-3-2-22, Mizuho-cho, Handa-city, Aichi Prefecture, East Town Room 206 (72) Invention Yuji Nomura 2-1-11 Kinjo, Kita-ku, Nagoya City, Aichi Prefecture, Co., Ltd. Wakaenzono E (56) References JP-A-59-83931 (JP, A) JP-A-5-17132 (JP, A) JP-A-6-316413 (JP, A) JP-A-7-331110 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C01F 7/02 C04B 35/10
Claims (3)
に混合し、これを中和することにより被覆層を得ること
からなる高可塑性アルミナ粒子の製造方法であって、ア
ルミナ水和物のアルミナに対する含有量が５〜５０重量
％であることを特徴とする高可塑性アルミナ粒子の製造
方法。1. A method for producing highly plastic alumina particles, comprising mixing alumina particles in an aluminum salt aqueous solution and neutralizing the mixture to obtain a coating layer. Is from 5 to 50% by weight.
処理を施すことを特徴とする請求項１記載の高可塑性ア
ルミナの製造方法。2. The method for producing highly plastic alumina according to claim 1, wherein the alumina particles containing alumina hydrate are subjected to a heat treatment.
ことを特徴とする請求項２記載の高可塑性アルミナ粒子
の製造方法。3. The method for producing highly plastic alumina particles according to claim 2 , wherein the temperature of the heat treatment is 300 to 700 ° C.
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|---|---|---|---|
| JP10169870A JP3035607B2 (en) | 1998-06-17 | 1998-06-17 | Highly plasticized alumina particles coated with alumina hydrate and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10169870A JP3035607B2 (en) | 1998-06-17 | 1998-06-17 | Highly plasticized alumina particles coated with alumina hydrate and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000007327A JP2000007327A (en) | 2000-01-11 |
| JP3035607B2 true JP3035607B2 (en) | 2000-04-24 |
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| JP5790243B2 (en) * | 2011-07-26 | 2015-10-07 | 株式会社デンソー | Method for manufacturing ceramic honeycomb structure |
| JP2014105146A (en) * | 2012-11-29 | 2014-06-09 | Hitachi Ltd | Preparation method of an alumina crystal particle-dispersed alumina sol, alumina crystal particle-dispersed alumina sol obtained by the same, and alumina-coated member prepared by using the same |
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1998
- 1998-06-17 JP JP10169870A patent/JP3035607B2/en not_active Expired - Lifetime
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