JP2008056563A - Method for producing compound oxide - Google Patents
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本発明は、複合酸化物の製造方法に関し、詳しくは金属の炭酸塩等の低融点金属化合物を原料に用いて効率よく複合酸化物を製造する複合酸化物の製造方法に関するものである。 The present invention relates to a method for producing a complex oxide, and more particularly to a method for producing a complex oxide that efficiently produces a complex oxide using a low melting point metal compound such as a metal carbonate as a raw material.
近年、複合酸化物は電子材料分野や電池材料分野で幅広く用いられている。例えば、チタン酸バリウム及びチタン酸ストロンチウムは、高誘電率を有するという電気的特性のため誘電体材料として有用であり、また、チタン酸リチウム、コバルト酸リチウム及びマンガン酸リチウムは、パソコン及び携帯電話等の電源に用いられるリチウム二次電池の電極の活物質として有用である。また、チタン酸カリウムは、結晶がウィスカー状であるため、金属又はプラスチックの補強材としても利用されている。 In recent years, complex oxides have been widely used in the field of electronic materials and battery materials. For example, barium titanate and strontium titanate are useful as dielectric materials because of their electrical properties of having a high dielectric constant, and lithium titanate, lithium cobaltate, and lithium manganate are used for personal computers and mobile phones, etc. It is useful as an active material for an electrode of a lithium secondary battery used for the power source of the battery. In addition, since potassium titanate has a whisker-like crystal, it is also used as a metal or plastic reinforcing material.
上記複合酸化物の製造方法としては従来から種々提案されており、大別すれば、固相法（焼成法）、溶融法、液相法（水熱法）に分類される。これらの方法のうちどの方法が好ましいかについては、得られる複合酸化物の特質がそれぞれの製造方法により異なるため一概には決められないが、固相法、すなわち原料を乾式方法で混合してそのまま焼成する製造方法は、工程が少なく製造コスト面で有利であるため、広く採用されている。 Various methods for producing the composite oxide have been proposed in the past, and can be roughly classified into a solid phase method (firing method), a melting method, and a liquid phase method (hydrothermal method). Which of these methods is preferable cannot be determined unconditionally because the characteristics of the resulting composite oxide differ depending on the production method. However, the solid phase method, that is, the raw materials are mixed by a dry method and left as it is. The manufacturing method for firing is widely adopted because it has fewer steps and is advantageous in terms of manufacturing cost.
固相法において複合酸化物は、通常、チタンやコバルト等の金属化合物と、カリウムやリチウム等の金属化合物とを反応させて得られる。ここで、チタン等の金属化合物としては酸化物が用いられることが多く、一方、カリウム等の金属化合物としては反応性に富むために炭酸塩や水酸化物が用いられることが多い。 In the solid phase method, the composite oxide is usually obtained by reacting a metal compound such as titanium or cobalt with a metal compound such as potassium or lithium. Here, oxides are often used as metal compounds such as titanium, while carbonates and hydroxides are often used as metal compounds such as potassium because of their high reactivity.
また、上記固相法を実施するに際し、チタン等の酸化物と、カリウム等の炭酸塩や水酸化物とを焼成する反応容器としては、工業的には、安価なセラミックス製容器が一般的に用いられている。 Moreover, when carrying out the solid phase method, as a reaction vessel for firing an oxide such as titanium and a carbonate or hydroxide such as potassium, an industrially inexpensive ceramic vessel is generally used. It is used.
しかしながら、カリウム等の炭酸塩や水酸化物は、反応性に富む一方、チタン等の酸化物との固相反応が開始される反応温度よりも融点が低い。このため、カリウム等の炭酸塩や水酸化物は、固相反応前に融解して一部がセラミックス製容器に浸透する。すると、カリウム等の炭酸塩や水酸化物のロスが生じるため、上記固相法では、チタン等の酸化物と、カリウム等の炭酸塩や水酸化物とを理論当量の割合で混合しても、所期の組成の複合酸化物が得られないという問題があった。 However, carbonates and hydroxides such as potassium are highly reactive, but have a melting point lower than the reaction temperature at which a solid phase reaction with an oxide such as titanium is started. For this reason, carbonates and hydroxides, such as potassium, melt | dissolve before solid-phase reaction, and one part osmose | permeates a ceramic container. Then, loss of carbonates and hydroxides such as potassium occurs, so in the solid phase method, even if oxides such as titanium and carbonates and hydroxides such as potassium are mixed at a ratio of theoretical equivalents. There is a problem that a composite oxide having the desired composition cannot be obtained.
なお、チタン酸バリウム、チタン酸カリウムやチタン酸リチウム等は、複数の金属成分の原子比が少しでも変動すると電子材料や電池材料に利用した際の静電容量などの電気的特性等の特性に非常に大きな影響が現れるため、所期の組成の複合酸化物が得られないことは重大な問題である。これに対し、従来は、原料のロス分を見込んで予めカリウム等の炭酸塩や水酸化物を多めに配合する方法が採用されている。しかし、このような方法を採用しても、カリウム等の炭酸塩や水酸化物の焼成時のロス分が一定でないため、得られた複合酸化物の組成にばらつきが生じたり、原料の歩留まりが悪く生産性が低かったりするという問題があった。 In addition, barium titanate, potassium titanate, lithium titanate, etc. have characteristics such as electrical characteristics such as capacitance when used in electronic materials and battery materials if the atomic ratio of multiple metal components fluctuates even a little. It is a serious problem that a complex oxide having a desired composition cannot be obtained because a very large effect appears. On the other hand, conventionally, a method in which a large amount of a carbonate or hydroxide such as potassium is blended in advance in consideration of the loss of the raw material has been employed. However, even if such a method is adopted, the amount of loss during firing of carbonates and hydroxides such as potassium is not constant, resulting in variations in the composition of the obtained composite oxide and the yield of raw materials. There was a problem that the productivity was poor.
また、上記固相法には、融解したカリウムやリチウム等の炭酸塩や水酸化物がセラミックス製容器に浸透すると、セラミックス製容器が劣化して強度や耐熱性が極端に低下し、容器の寿命が短くなるという問題もあった。なお、反応容器としては、セラミックス製容器以外に白金やモリブデン等からなる金属製容器も知られているが、これらは高価であるため工業的には通常は用いられない。 Also, in the above solid phase method, when carbonate or hydroxide such as molten potassium or lithium penetrates into a ceramic container, the ceramic container deteriorates and the strength and heat resistance are extremely reduced, and the life of the container is reduced. There was also a problem that became shorter. In addition to the ceramic container, a metal container made of platinum, molybdenum, or the like is also known as the reaction container, but these are expensive and are not usually used industrially.
従って、本発明の目的は、固相法において、原料のロスがなく容易に所期の組成通りの複合酸化物が得られると共に、セラミックス製反応容器の劣化を抑制し得る複合酸化物の製造方法を提供することにある。 Accordingly, an object of the present invention is to provide a method for producing a composite oxide that can easily obtain a composite oxide having a desired composition without loss of raw materials and can suppress deterioration of a ceramic reaction vessel in a solid phase method. Is to provide.
かかる実情において、本発明者らは鋭意検討を行った結果、固相法でチタン等の酸化物とカリウムの炭酸塩等との混合粉末を焼成するに際し、セラミックス製反応容器と前記混合粉末との間に、炭化する材質からなるシート材を介在させ、該シート材への酸素の侵入を実質的に防止して焼成すれば、焼成途中にシート材の炭化した層が形成され、該炭化した層が焼成時に溶融したカリウムの炭酸塩等のセラミックス製反応容器内壁への浸透を阻むと共に、該炭化した層は固相法における反応温度において焼失するため、得られる複合酸化物中に炭化物が不純物として残存することもないことを見出し、本発明を完成するに至った。 In such a situation, the present inventors have intensively studied. As a result, when firing a mixed powder of an oxide such as titanium and potassium carbonate by a solid phase method, the ceramic reaction vessel and the mixed powder If a sheet material made of carbonized material is interposed between the sheet material and firing is performed while substantially preventing oxygen from entering the sheet material, a carbonized layer of the sheet material is formed during the firing, and the carbonized layer Prevents the penetration of potassium carbonate melted during firing into the inner wall of the reaction vessel made of ceramics, and the carbonized layer is burned off at the reaction temperature in the solid phase method, so that carbide is an impurity in the resulting composite oxide. The inventors have found that it does not remain, and have completed the present invention.
すなわち、本発明は、チタン、コバルト及びマンガンからなる群より選択される少なくとも１種の酸化物又は水酸化物である第１金属化合物と、リチウム、ナトリウム、カリウム、マグネシウム、カルシウム、ストロンチウム、バリウム及びランタンからなる群より選択される少なくとも１種の炭酸塩又は水酸化物である第２金属化合物とを含む混合粉末を、セラミックス製反応容器に充填し焼成する複合酸化物の製造方法であって、前記セラミックス製反応容器と前記混合粉末との間の少なくとも該セラミックス製反応容器の底部に、炭化する材質からなるシート材を介在させ、該シート材への酸素の侵入を実質的に防止して焼成することを特徴とする複合酸化物の製造方法を提供するものである。 That is, the present invention relates to a first metal compound that is at least one oxide or hydroxide selected from the group consisting of titanium, cobalt and manganese, lithium, sodium, potassium, magnesium, calcium, strontium, barium and A mixed oxide containing at least one carbonate selected from the group consisting of lanthanum and a second metal compound that is a hydroxide, filled in a ceramic reaction vessel and fired, and a method for producing a composite oxide, A sheet material made of carbonized material is interposed at least at the bottom of the ceramic reaction vessel between the ceramic reaction vessel and the mixed powder, and substantially prevents oxygen from entering the sheet material and fires. The present invention provides a method for producing a composite oxide.
本発明の方法によれば、固相法による複合酸化物の製造においてセラミックス製の反応容器の内壁に紙等のシート材を装入しその中に原料の混合粉末を装入して焼成するため、昇温途中で溶融した原料の金属化合物がセラミックス製容器内に浸透することなく反応させることが可能となり、結果として目的の組成を有する複合酸化物を安定して製造することができ、且つ、セラミックス製反応容器を劣化させることなくその寿命を延ばすことができる。 According to the method of the present invention, in the production of a complex oxide by the solid phase method, a sheet material such as paper is charged into the inner wall of a ceramic reaction vessel, and the mixed powder of raw materials is charged therein and fired. It is possible to react the raw metal compound melted in the middle of the temperature rise without penetrating into the ceramic container, and as a result, it is possible to stably produce a composite oxide having the desired composition, and The lifetime can be extended without deteriorating the ceramic reaction vessel.
本発明において、複合酸化物の原料である混合粉末は、第１金属化合物と第２金属化合物とからなるものである。 In the present invention, the mixed powder that is a raw material of the composite oxide is composed of a first metal compound and a second metal compound.
本発明において第１金属化合物とは、チタン、コバルト及びマンガンからなる群より選択される少なくとも１種の酸化物又は水酸化物をいう。具体的には、酸化チタン、水酸化チタン、酸化コバルト、水酸化コバルト、酸化マンガン、水酸化マンガンが挙げられる。第１金属化合物の形態としては粉末状、粒状、塊状等、特に限定されないが、粒径１００μｍ以下の粉末状であることが焼結した際の反応性向上のため好ましい。第１金属化合物は、１種又は２種以上組み合わせて用いられる。 In the present invention, the first metal compound refers to at least one oxide or hydroxide selected from the group consisting of titanium, cobalt, and manganese. Specific examples include titanium oxide, titanium hydroxide, cobalt oxide, cobalt hydroxide, manganese oxide, and manganese hydroxide. The form of the first metal compound is not particularly limited, such as powder, granule, and lump, but is preferably a powder having a particle size of 100 μm or less in order to improve reactivity when sintered. The first metal compound is used alone or in combination of two or more.
本発明において第２金属化合物とは、リチウム、ナトリウム、カリウム、マグネシウム、カルシウム、ストロンチウム、バリウム及びランタンからなる群より選択される少なくとも１種の炭酸塩又は水酸化物をいう。具体的には、炭酸リチウム、水酸化リチウム、炭酸ナトリウム、重炭酸ナトリウム、水酸化ナトリウム、炭酸カリウム、重炭酸カリウム、水酸化カリウム、炭酸マグネシウム、水酸化マグネシウム、炭酸カルシウム、水酸化カルシウム、炭酸ストロンチウム、水酸化ストロンチウム、炭酸バリウム、水酸化バリウム、炭酸ランタン、水酸化ランタン等が挙げられる。第２金属化合物の形態としては粉末状、粒状、塊状等、特に限定されないが、粒径１００μｍ以下の粉末状であることが焼結した際の反応性向上のため好ましい。第２金属化合物は、１種又は２種以上組み合わせて用いられる。 In the present invention, the second metal compound means at least one carbonate or hydroxide selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, strontium, barium and lanthanum. Specifically, lithium carbonate, lithium hydroxide, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium hydroxide, strontium carbonate Strontium hydroxide, barium carbonate, barium hydroxide, lanthanum carbonate, lanthanum hydroxide and the like. The form of the second metal compound is not particularly limited, such as powder, granule, and lump, but is preferably a powder having a particle size of 100 μm or less in order to improve reactivity when sintered. A 2nd metal compound is used 1 type or in combination of 2 or more types.
本発明において混合粉末は、上記の第１金属化合物と第２金属化合物とを混合してなるものである。混合粉末は複合酸化物の原料であるが、複合酸化物と、混合粉末の調製の際における第１金属化合物及び第２金属化合物との組み合わせとしては、好ましくは以下のものが挙げられる。 In the present invention, the mixed powder is obtained by mixing the first metal compound and the second metal compound. Although the mixed powder is a raw material for the composite oxide, the combination of the composite oxide and the first metal compound and the second metal compound in the preparation of the mixed powder preferably includes the following.
すなわち、複合酸化物がチタン酸カリウムである場合には、第１金属化合物が酸化チタンで、第２金属化合物が炭酸カリウム又は重炭酸カリウムであることが好ましい。ここで、チタン酸カリウムとしては、具体的には、ニチタン酸カリウムＫ2Ｏ・２ＴｉＯ2（Ｋ2ＴｉＯ5）、四チタン酸カリウムＫ2Ｏ・４ＴｉＯ2（Ｋ2ＴｉＯ9）、六チタン酸カリウムＫ2Ｏ・６ＴｉＯ2（Ｋ2ＴｉＯ13）及び八チタン酸カリウムＫ2Ｏ・８ＴｉＯ2（Ｋ2ＴｉＯ17）等が挙げられる。 That is, when the composite oxide is potassium titanate, the first metal compound is preferably titanium oxide and the second metal compound is preferably potassium carbonate or potassium bicarbonate. Here, as potassium titanate, specifically, potassium titanate K 2 O · 2TiO 2 (K 2 TiO 5 ), potassium tetratitanate K 2 O · 4TiO 2 (K 2 TiO 9 ), hexatitanate potassium K 2 O · 6TiO 2 (K 2 TiO 13) and potassium eight titanate K 2 O · 8TiO 2 (K 2 TiO 17) , and the like.
また、複合酸化物がチタン酸リチウムである場合には、第１金属化合物が酸化チタンで、第２金属化合物が炭酸リチウムであることが好ましい。ここで、チタン酸リチウムとしては、具体的には、Ｌｉ4Ｔｉ5Ｏ12、Ｌｉ2Ｔｉ3Ｏ7及びＬｉＴｉ2Ｏ4等が挙げられる。 When the composite oxide is lithium titanate, it is preferable that the first metal compound is titanium oxide and the second metal compound is lithium carbonate. Here, specific examples of lithium titanate include Li 4 Ti 5 O 12 , Li 2 Ti 3 O 7, and LiTi 2 O 4 .
また、複合酸化物がチタン酸ストロンチウムである場合には、第１金属化合物が酸化チタンで、第２金属化合物が炭酸ストロンチウムであることが好ましい。また、複合酸化物がチタン酸ナトリウムである場合には、第１金属化合物が酸化チタンで、第２金属化合物が炭酸ナトリウムであることが好ましい。 When the composite oxide is strontium titanate, it is preferable that the first metal compound is titanium oxide and the second metal compound is strontium carbonate. When the composite oxide is sodium titanate, it is preferable that the first metal compound is titanium oxide and the second metal compound is sodium carbonate.
これらの組み合わせのうち、複合酸化物がチタン酸カリウムである場合に、第１金属化合物を酸化チタンとし、第２金属化合物を炭酸カリウムとする組み合わせは反応性が向上するため特に好ましい。 Among these combinations, when the composite oxide is potassium titanate, a combination in which the first metal compound is titanium oxide and the second metal compound is potassium carbonate is particularly preferable because the reactivity is improved.
混合粉末を調製する方法としては、特に限定されず、乾式混合法又は湿式混合法のいずれも採用することができる。また、混合の際に用いられる混合手段としては、Ｖ型ブレンダー、ボールミル等の公知の混合手段を用いることができる。また、第１金属化合物又は第２金属化合物の少なくともいずれか一方が、粉体でなく流状物又は塊状物である場合には、ボールミル等の粉砕混合手段を用いて混合粉末を調製することが好ましい。 The method for preparing the mixed powder is not particularly limited, and either a dry mixing method or a wet mixing method can be employed. Moreover, as a mixing means used at the time of mixing, well-known mixing means, such as a V-type blender and a ball mill, can be used. When at least one of the first metal compound and the second metal compound is not a powder but a fluid or a lump, a mixed powder can be prepared using a pulverizing and mixing means such as a ball mill. preferable.
また、湿式混合法の場合、溶媒としては純水、アルコール、アセトン、ＭＥＫ、ＴＨＦ等の通常の有機溶媒等が用いられるが、混合粉末の分散性を向上させて均一に混合させるために、界面活性剤や分散剤を併用することが好ましい。 In the case of the wet mixing method, a pure organic solvent such as pure water, alcohol, acetone, MEK, or THF is used as the solvent. In order to improve the dispersibility of the mixed powder and uniformly mix the interface, It is preferable to use an activator or a dispersant in combination.
また、混合粉末には、必要により、さらに金属チタン粉を含ませてもよい。このように金属チタン粉を配合すると金属チタン粉が空気を吸収するため、焼成工程において、炭化する材質からなるシート材が炭化し易くなるため好ましい。 Further, the mixed powder may further contain titanium metal powder as required. When the titanium metal powder is blended in this manner, the titanium metal powder absorbs air, and therefore, in the firing step, a sheet material made of a carbonized material is easily carbonized, which is preferable.
本発明で用いられるセラミックス製反応容器としては、アルミナ等の通常のセラミックス材料からなるものであって、上記混合粉末を載置又は装入したときに混合粉末との間になるべく空気が侵入し難い形状のものが用いられる。具体的には、円筒状物、凹部を有する円柱状物、凹部を有する方形状物、皿状物等が挙げられる。このうち、円柱状物又は方形状物であってこれらの一部に形成された凹部がある程度の深さを有するものは、焼成において空気中の酸素の侵入を防止するため好ましい。 The ceramic reaction vessel used in the present invention is made of a normal ceramic material such as alumina, and it is difficult for air to enter between the mixed powder when the mixed powder is placed or loaded. A shape is used. Specific examples include a cylindrical object, a columnar object having a recess, a rectangular object having a recess, a dish-like object, and the like. Among these, a cylindrical or rectangular object having a certain depth of recesses formed in a part of these is preferable in order to prevent infiltration of oxygen in the air during firing.
本発明では、上記セラミックス製反応容器に上記混合粉末を充填するに当たり、セラミックス製反応容器と混合粉末との間の少なくともセラミックス製反応容器の底部に、炭化する材質からなるシート材を介在させる。このように、シート材を介在させることにより、焼成時に混合粉末中の第２金属化合物が溶融して、第２金属化合物がロスしたり、セラミックス製反応容器に溶融した第２金属化合物が浸透したりすることを回避できる。また、これらのシート材は、少なくともセラミックス製反応容器の凹部が形成する内壁部における前記混合粉末との接触部に介在させると、第２金属化合物のロスや、セラミックス製反応容器への浸透をより確実に回避できるためより好ましい。さらに、これらのシート材は、セラミックス製反応容器の凹部が形成する内壁部全体に介在させると、第２金属化合物のロスや、セラミックス製反応容器への浸透を略完全に回避できるため特に好ましい。 In the present invention, when filling the ceramic reaction vessel with the mixed powder, a sheet material made of a carbonizing material is interposed at least at the bottom of the ceramic reaction vessel between the ceramic reaction vessel and the mixed powder. In this way, by interposing the sheet material, the second metal compound in the mixed powder melts at the time of firing, the second metal compound is lost, or the molten second metal compound penetrates into the ceramic reaction vessel. Can be avoided. Further, when these sheet materials are interposed at least in the contact portion with the mixed powder in the inner wall portion formed by the concave portion of the ceramic reaction vessel, the loss of the second metal compound and the penetration into the ceramic reaction vessel are further reduced. It is more preferable because it can be surely avoided. Furthermore, it is particularly preferable that these sheet materials are interposed in the entire inner wall portion formed by the concave portion of the ceramic reaction vessel because the loss of the second metal compound and the penetration into the ceramic reaction vessel can be avoided almost completely.
炭化する材質からなるシート材は、焼成したときに炭化し、且つ、最終的に焼失すると共に、焼成時に軟化物又は流動物を生成しない材質のものが用いられ、具体的には、紙、天然繊維、樹皮又は熱硬化性樹脂が用いられる。例えば、紙の場合には、炭化し難く軟化する塩化ビニール等のようなものが張り合わされていない通常の紙が用いられ、いわゆる未晒クラフト紙、両更晒クラフト紙、片艶晒などの包装用紙、段ボール原紙、新聞用紙、上質紙、中質紙、再生紙、書籍用紙、キャストコート紙、 アート紙、ＰＰＣ用紙などの情報用紙等が用いられる。また、天然繊維としては、例えば綿、麻、絹等が用いられる。また、熱硬化性樹脂としては、例えばフェノール樹脂、エポキシ樹脂、メラミン樹脂等が用いられる。 The sheet material made of carbonized material is carbonized when fired and finally burned out, and is made of a material that does not generate softened or fluidized material when fired. Fiber, bark or thermosetting resin is used. For example, in the case of paper, ordinary paper that is hard to be carbonized and not softened such as vinyl chloride is used, and so-called unbleached kraft paper, double-bleached kraft paper, packaging such as single gloss bleach Information paper such as paper, corrugated cardboard, newsprint, high-quality paper, medium-quality paper, recycled paper, book paper, cast-coated paper, art paper, and PPC paper is used. Moreover, as natural fiber, cotton, hemp, silk, etc. are used, for example. Moreover, as a thermosetting resin, a phenol resin, an epoxy resin, a melamine resin etc. are used, for example.
上記炭化する材質からなるシート材の形状は、シート、織布、不織布又は袋とする。特に袋状とすると混合粉末を充填させた状態でセラミックス製反応容器等に充填できるため、作業が容易になるため好ましい。また、シート材に用いられる紙の密度は、シート材が焼成の際に形成する炭化物膜等の炭化物の層が溶融した第２金属化合物を浸透させない程度の密度及び強度を有する必要があるため、紙の重さを表わす「坪量」が３０〜１００g/m2程度であることが好ましい。 The shape of the sheet material made of the carbonized material is a sheet, a woven fabric, a non-woven fabric, or a bag. In particular, a bag shape is preferable because it can be filled into a ceramic reaction vessel or the like in a state where the mixed powder is filled, and the work becomes easy. In addition, the density of the paper used for the sheet material needs to have a density and strength such that the second metal compound in which the carbide layer such as a carbide film formed when the sheet material is fired does not penetrate the molten second metal compound, The “basis weight” representing the weight of the paper is preferably about 30 to 100 g / m 2 .
本発明では、上記のようにセラミックス製反応容器に炭化する材質からなるシート材を介在させて混合粉末を充填した後、該シート材への酸素の侵入を実質的に防止して焼成する。ここで、酸素の侵入を実質的に防止するとは、加熱し、固相反応が開始する前に、該シート材が燃焼しないように反応容器内への酸素の侵入を防止する意味であり、通常は、シート材を敷き詰めたセラミックス製反応容器に原料の混合粉末を隙間のないようにある程度充填することで達成できる。また、酸素の侵入を防止する方法として、密閉可能な電気炉等のように外部からの酸素の供給を遮断できる構造の加熱炉を用いて行うか、あるいは、加熱炉自体が密閉できず、炉内への酸素の供給が避けられない場合でも、セラミックス製反応容器を、円筒状物、凹部を有する円柱状物、凹部を有する方形状物等とし、これらを密閉して炉内の雰囲気から遮断する方法を採ればより好ましい。また、加熱炉内部又はセラミックス製反応容器内部のいずれか又は両方を、窒素雰囲気中又はアルゴン雰囲気中にして焼成を行うと、より確実に上記シート材への酸素の侵入を防止して焼成することができるため好ましい。 In the present invention, as described above, a sheet material made of carbonized material is interposed in the ceramic reaction vessel and filled with the mixed powder, and then fired while substantially preventing oxygen from entering the sheet material. Here, substantially preventing oxygen from entering means to prevent oxygen from entering the reaction vessel so that the sheet material does not burn before heating and the solid-phase reaction is started. Can be achieved by filling the mixed powder of the raw material to a certain extent so that there is no gap in a ceramic reaction vessel laid with a sheet material. Further, as a method for preventing oxygen from entering, a heating furnace having a structure capable of shutting off the supply of oxygen from the outside, such as a sealable electric furnace, is used, or the heating furnace itself cannot be sealed, and the furnace Even when oxygen supply is unavoidable, the ceramic reaction vessel should be a cylindrical object, a cylindrical object having a recess, a rectangular object having a recess, etc., which are sealed from the atmosphere in the furnace. It is more preferable to adopt the method to do. In addition, if firing is performed in a nitrogen atmosphere or an argon atmosphere in either or both of the inside of the heating furnace and the ceramic reaction vessel, firing is performed more reliably preventing oxygen from entering the sheet material. Is preferable.
本発明において、焼成温度は複合酸化物の種類により異なり、例えば、複合酸化物がチタン酸カリウムであれば、通常８００〜１２００℃、好ましくは１０００〜１１５０℃であり、複合酸化物がチタン酸リチウムであれば、通常７００〜１０００℃、好ましくは８００〜９５０℃である。このように複合酸化物は、通常７００以上、時には１０００℃以上で固相反応が開始するが、本発明では、該温度に至るまでの加熱途中で、セラミックス製反応容器との間に介在させた炭化する材質からなるシート材が炭化して炭化層を形成するため、溶融した第２金属化合物がセラミックス製反応容器に直接接触することを回避することができる。
なお、炭化層は、固相反応が開始する温度まで加熱されると、固相反応の際に生成する炭酸ガス等と反応して一酸化炭素等を生成して消滅するため、固相反応終了後に生成される複合酸化物中に不純物として残存することがなく、炭化層を形成して焼成しても複合酸化物の品質には影響しない。
In the present invention, the firing temperature varies depending on the type of composite oxide. For example, if the composite oxide is potassium titanate, it is usually 800 to 1200 ° C., preferably 1000 to 1150 ° C., and the composite oxide is lithium titanate. If it is, it is 700-1000 degreeC normally, Preferably it is 800-950 degreeC. As described above, the composite oxide usually starts a solid-phase reaction at 700 ° C. or higher, sometimes 1000 ° C. or higher. In the present invention, the composite oxide is interposed between the ceramic reaction vessel and the heating to reach this temperature. Since the sheet material made of the carbonized material is carbonized to form a carbonized layer, it is possible to avoid the molten second metal compound from coming into direct contact with the ceramic reaction vessel.
When the carbonized layer is heated to a temperature at which the solid-phase reaction starts, it reacts with carbon dioxide gas generated during the solid-phase reaction to generate carbon monoxide and the like, which disappears. It does not remain as an impurity in the composite oxide produced later, and the quality of the composite oxide is not affected even if a carbonized layer is formed and fired.
焼成で得られた複合酸化物は、降温後、必要によりボールミル等で粉砕する。また、必要により、該粉砕物を水中等で攪拌処理して繊維状物とし、濾過後、該繊維状物を乾燥し、常法により焼成すればウィスカー状のものを得ることができる。 The composite oxide obtained by firing is pulverized by a ball mill or the like as necessary after the temperature is lowered. Further, if necessary, the pulverized product is agitated in water or the like to form a fibrous product, and after filtration, the fibrous product is dried and baked by a conventional method to obtain a whisker-like product.
以下に、得られる複合酸化物がチタン酸カリウムウィスカーである場合の製造方法の具体例を示す。まず、セラミックス製で上部が開放された円筒状の反応容器の内壁に、クラフト紙からなり前記反応容器内壁の形状に一致する形状・大きさの袋を装入する。次に、該袋に炭酸カリウム、酸化チタン鉱石粉末及び金属チタン粉を混合した混合粉末を反応容器の上部まで隙間のないように充填する。これにより、袋は空気との接触が遮断された状態にある。その後、徐々に加熱し、１１００℃で３時間反応させる。さらに、徐々に降温した後、別容器へ移して粉砕する。次いで、水又は温水中で攪拌機により強制的に５〜１０時間攪拌処理を行い、その後コロイドミルにて解繊する。得られた繊維状物を中和水洗後濾過し、１００〜２５０℃で乾燥させたものを８００℃にて焼成すれば、繊維状のチタン酸カリウムが得られる。 Below, the specific example of the manufacturing method in case the complex oxide obtained is a potassium titanate whisker is shown. First, a bag made of kraft paper and having a shape and size corresponding to the shape of the inner wall of the reaction vessel is placed on the inner wall of a cylindrical reaction vessel made of ceramic and opened at the top. Next, the mixed powder obtained by mixing potassium carbonate, titanium oxide ore powder and metal titanium powder is filled into the bag so that there is no gap up to the top of the reaction vessel. Thereby, the bag is in a state where contact with air is blocked. Then, it heats gradually and makes it react at 1100 degreeC for 3 hours. Furthermore, after the temperature is gradually lowered, it is transferred to another container and pulverized. Next, the mixture is forcibly stirred with a stirrer in water or warm water for 5 to 10 hours, and then defibrated with a colloid mill. If the obtained fibrous material is washed with neutralized water, filtered, and dried at 100 to 250 ° C. and fired at 800 ° C., fibrous potassium titanate is obtained.
本発明に係る複合酸化物の製造方法は、例えばチタン酸カリウム等の複合酸化物の製造に用いることができる。特に、焼成の際に溶融する低融点原料を用いる製造方法に好適である。 The method for producing a complex oxide according to the present invention can be used for producing a complex oxide such as potassium titanate. In particular, it is suitable for a production method using a low-melting-point raw material that melts during firing.
次に、実施例を挙げて本発明を更に具体的に説明するが、これは単に例示であって本発明を制限するものではない。 EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.
実施例１
顔料用酸化チタンと粉末状炭酸カリウムとを、正味の酸化チタンのモル数と正味の炭酸カリウムのモル数とのモル比が３：１の割合で混合し、該混合物に対して５重量％のチタン粉末を添加してＶ型ブレンダーにて約１５分間混合した。次いで、上部が開放されたセラミックス製反応容器内に、クラフト紙で形成され且つ一部が開放されると共にセラミックス製反応容器内壁に略密着し得る形状及び大きさを有する袋を装入し、該袋の上に前記混合物５００gを隙間のないよう密に充填した。このようにして、クラフト紙に酸素が侵入し難い状態を形成した。その後、混合粉末及びクラフト紙が充填されたセラミックス製反応容器を電気炉に入れ、１１００℃で３時間の焼成を行った。除冷後、該焼成物を取り出した後、３ｌの冷水中に浸してスラリー状とし、該スラリーをディスパーミルによって解繊して繊維状物質を分離した。解繊分離したスラリーを中和した後、真空濾過法によって、濾過することによりケーキ状物質を得、該ケーキ状物質を乾燥し、８００℃に昇温して３０分間熱処理を行った。このようにして、繊維径が平均０．５μm、繊維長が５０μmの単体の六チタン酸カリウムを４０６g得た。上記の製造を同じセラミックス容器を用いて繰り返し行ったところ、３０回の使用においてもセラミックス製反応容器は劣化しなかった。
なお、混合粉末及びクラフト紙が充填されたセラミックス製反応容器を電気炉に入れるまでは上記と同じ工程を行った後、同様の条件で焼成を開始し、昇温途中の４００℃で昇温を停止し、徐々に冷却して室温になったところでセラミックス製反応容器を取り出した。セラミックス製反応容器の内壁を観察したところ、炭化層が形成されていた。
Example 1
Titanium oxide for pigment and powdered potassium carbonate are mixed at a molar ratio of 3: 1 net titanium oxide to net potassium carbonate in a ratio of 3: 1 and 5% by weight based on the mixture. Titanium powder was added and mixed for about 15 minutes in a V-type blender. Next, in a ceramic reaction vessel with an open top, a bag made of kraft paper and partially open and having a shape and size that can be in close contact with the inner wall of the ceramic reaction vessel is loaded, 500 g of the mixture was tightly packed on the bag without any gaps. Thus, a state in which oxygen hardly enters the kraft paper was formed. Thereafter, the ceramic reaction vessel filled with the mixed powder and kraft paper was placed in an electric furnace and baked at 1100 ° C. for 3 hours. After the cooling, the fired product was taken out and immersed in 3 l of cold water to form a slurry. The slurry was defibrated by a disper mill to separate the fibrous material. After neutralizing the defibrated and separated slurry, it was filtered by a vacuum filtration method to obtain a cake-like substance. The cake-like substance was dried, heated to 800 ° C., and heat-treated for 30 minutes. Thus, 406 g of simple potassium hexatitanate having an average fiber diameter of 0.5 μm and a fiber length of 50 μm was obtained. When the above production was repeated using the same ceramic container, the ceramic reaction container did not deteriorate even after 30 uses.
The same process as described above was carried out until the ceramic reaction vessel filled with the mixed powder and kraft paper was put into the electric furnace, and then firing was started under the same conditions, and the temperature was raised at 400 ° C. during the temperature rise. After stopping and gradually cooling to room temperature, the ceramic reaction vessel was taken out. When the inner wall of the ceramic reaction vessel was observed, a carbonized layer was formed.
比較例１
上部が開放されたセラミックス製反応容器内に、クラフト紙で形成された袋を装入しなかった以外は、実施例１と同様にして、繊維径が平均０．５μm、繊維長が５０μmの六チタン酸カリウムを３６４g得た。
上記の製造を同じセラミックス容器を用いて繰り返し行ったところ、１５回目でセラミックス製反応容器にひび割れが生じ、使用不可能となった。
Comparative Example 1
In the same manner as in Example 1, except that a bag made of kraft paper was not placed in a ceramic reaction vessel having an open top, six fibers having an average fiber diameter of 0.5 μm and a fiber length of 50 μm were used. 364 g of potassium titanate was obtained.
When the above production was repeated using the same ceramic container, the ceramic reaction container cracked at the fifteenth time and became unusable.
実施例２
酸化チタン粉末（東邦チタニウム株式会社製、ルチル化率９０％）２９１．５gと粉末状炭酸カリウム１０８．７５gとを、大気雰囲気のグローブボックス内でＬｉ／Ｔｉのモル比が０．８０となるように原料を採取した。次いで、酸化チタン粉末と炭酸リチウム粉末とをロッキングミキサーに充填し、２時間かけて混合した。次いで、直径１０．５cm、長さ１００cmの円筒形状のアルミナ製反応管内に、クラフト紙で形成され且つ一部が開放されると共にセラミックス製反応容器内壁に略密着し得る形状及び大きさを有する袋を装入し、該袋の上に前記混合粉末１００gを隙間のないよう密に充填した。このようにして、クラフト紙に酸素が侵入し難い状態を形成した。その後、該シート材を加熱炉に入れ９００℃で４．５時間保持し焼成を行い、Ｌｉ4Ｔｉ5Ｏ12の組成を有するスピネル型のチタン酸リチウム粉末を３３０g得た。該チタン酸リチウム粉末を化学分析してＬｉ／Ｔｉのモル比を求めたところ、０．７９５であり、略目的通りの組成のチタン酸バリウムが得られた。上記の製造を同じアルミナ製反応管を用いて繰り返し行ったところ、２０回の使用においてもアルミナ製反応管は劣化しなかった。
なお、混合粉末及びクラフト紙が充填されたアルミナ製反応管を加熱炉に入れるまでは上記と同じ工程を行った後、同様の条件で焼成を開始し、昇温途中の４００℃で昇温を停止し、徐々に冷却してアルミナ製反応管を取り出した。アルミナ製反応管の内壁を観察したところ、炭化層が形成されていた。
Example 2
291.5 g of titanium oxide powder (manufactured by Toho Titanium Co., Ltd., 90% rutile ratio) and 108.75 g of powdered potassium carbonate so that the molar ratio of Li / Ti is 0.80 in a glove box in an air atmosphere. Ingredients were collected. Next, the titanium oxide powder and the lithium carbonate powder were filled in a rocking mixer and mixed for 2 hours. Next, in a cylindrical alumina reaction tube having a diameter of 10.5 cm and a length of 100 cm, a bag made of kraft paper and partially opened and having a shape and size that can be in close contact with the inner wall of the ceramic reaction vessel And 100 g of the mixed powder was tightly filled on the bag without any gaps. Thus, a state in which oxygen hardly enters the kraft paper was formed. Then, the sheet material was put in a heating furnace and held at 900 ° C. for 4.5 hours and baked to obtain 330 g of spinel type lithium titanate powder having a composition of Li 4 Ti 5 O 12 . The lithium titanate powder was chemically analyzed to obtain a Li / Ti molar ratio of 0.795. Barium titanate having a composition almost as intended was obtained. When the above production was repeated using the same alumina reaction tube, the alumina reaction tube did not deteriorate even after 20 uses.
The same process as described above was carried out until the alumina reaction tube filled with the mixed powder and kraft paper was put into the heating furnace, and then firing was started under the same conditions, and the temperature was raised at 400 ° C. during the temperature raising. The reaction was stopped, the mixture was gradually cooled, and the alumina reaction tube was taken out. When the inner wall of the alumina reaction tube was observed, a carbonized layer was formed.
比較例２
アルミナ製反応管内に、クラフト紙で形成された袋を装入しなかった以外は、実施例２と同様にしてチタン酸リチウム粉末を２９０g得た。該チタン酸リチウム粉末を化学分析してＬｉ／Ｔｉのモル比を求めたところ、０．６９０であり、Ｌｉ分が目的とする組成より少なかった。上記の製造を同じアルミナ製反応管を用いて繰り返し行ったところ、８回目でアルミナ製反応管にひび割れが生じ、使用不可能となった。
Comparative Example 2
290 g of lithium titanate powder was obtained in the same manner as in Example 2 except that the bag made of kraft paper was not charged into the alumina reaction tube. When the lithium titanate powder was chemically analyzed to determine the molar ratio of Li / Ti, it was 0.690, and the Li content was less than the target composition. When the above production was repeated using the same alumina reaction tube, the alumina reaction tube cracked in the 8th time and became unusable.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8178072B2 (en) | 2007-10-15 | 2012-05-15 | Toho Titanium Co., Ltd. | Method of manufacturing alkali metal titanate |
| CN105050958A (en) * | 2013-03-18 | 2015-11-11 | 东邦钛株式会社 | Method for producing potassium titanate |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58135130A (en) * | 1982-02-03 | 1983-08-11 | Res Inst For Prod Dev | Preparation of reduced alkali titanate |
| JPH03279215A (en) * | 1990-03-29 | 1991-12-10 | Nippon Uisukaa Kk | Production of potassium hexatitanate fiber |
| JPH05148064A (en) * | 1991-11-26 | 1993-06-15 | Inax Corp | Production of mosaic tile |
| JPH05229875A (en) * | 1992-02-18 | 1993-09-07 | Rohm Co Ltd | Production of ceramic substrate |
| JPH07309672A (en) * | 1994-05-17 | 1995-11-28 | Tanaka Seishi Kogyo Kk | Sheet for firing of ceramic substrate |
-
2007
- 2007-11-19 JP JP2007298765A patent/JP4852022B2/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58135130A (en) * | 1982-02-03 | 1983-08-11 | Res Inst For Prod Dev | Preparation of reduced alkali titanate |
| JPH03279215A (en) * | 1990-03-29 | 1991-12-10 | Nippon Uisukaa Kk | Production of potassium hexatitanate fiber |
| JPH05148064A (en) * | 1991-11-26 | 1993-06-15 | Inax Corp | Production of mosaic tile |
| JPH05229875A (en) * | 1992-02-18 | 1993-09-07 | Rohm Co Ltd | Production of ceramic substrate |
| JPH07309672A (en) * | 1994-05-17 | 1995-11-28 | Tanaka Seishi Kogyo Kk | Sheet for firing of ceramic substrate |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8178072B2 (en) | 2007-10-15 | 2012-05-15 | Toho Titanium Co., Ltd. | Method of manufacturing alkali metal titanate |
| CN105050958A (en) * | 2013-03-18 | 2015-11-11 | 东邦钛株式会社 | Method for producing potassium titanate |
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| Publication number | Publication date |
|---|---|
| JP4852022B2 (en) | 2012-01-11 |
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