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WO2022070784A1 - Method for producing strontium titanate microparticles - Google Patents

Method for producing strontium titanate microparticles Download PDF

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Publication number
WO2022070784A1
WO2022070784A1 PCT/JP2021/032617 JP2021032617W WO2022070784A1 WO 2022070784 A1 WO2022070784 A1 WO 2022070784A1 JP 2021032617 W JP2021032617 W JP 2021032617W WO 2022070784 A1 WO2022070784 A1 WO 2022070784A1
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WIPO (PCT)
Prior art keywords
fine particles
strontium titanate
strontium
titanate fine
hydrazine
Prior art date
Application number
PCT/JP2021/032617
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French (fr)
Japanese (ja)
Inventor
健嗣 小倉
圭祐 池堂
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サカタインクス株式会社
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Publication date
Priority claimed from JP2021028960A external-priority patent/JP2022058092A/en
Application filed by サカタインクス株式会社 filed Critical サカタインクス株式会社
Priority to CN202180056082.XA priority Critical patent/CN116096677B/en
Priority to KR1020237004330A priority patent/KR20230075395A/en
Publication of WO2022070784A1 publication Critical patent/WO2022070784A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/003—Titanates
    • C01G23/006—Alkaline earth titanates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer

Definitions

  • the present invention relates to a method for producing strontium titanate fine particles.
  • strontium titanate (SrTiO 3 ) has dielectric properties, thermoelectric properties, photocatalytic activity, high refractive index properties, etc., it is expected to be used in various applications as a functional material.
  • Patent Document 1 strontium titanate having an average particle size of 50 nm or less, an average aspect ratio of 1.0 to 1.2, and a refractive index of 1.8 to 2.6 has a high refractive index. Is disclosed. Further, Patent Document 1 discloses that when strontium titanate is used as a component that imparts high refractive index property, high dispersibility that does not aggregate in the coating film is required.
  • An object of the present invention is to provide a method for producing strontium titanate fine particles, which can produce strontium titanate fine particles having excellent dispersibility under simple conditions.
  • the present inventors have diligently studied a method for producing strontium titanate fine particles, and found that a specific amount of hydrazine or hydrazide compound is contained, and the organic titanium acid ester is reacted with the strontium compound under predetermined conditions (temperature and reaction time). As a result, it has been found that strontium titanate fine particles having excellent dispersibility can be produced in a shorter reaction time than before.
  • the present invention presents the organic titanium acid ester and the strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or more and 250 ° C. or less, and a reaction time of 0.5 hours or more and 2 hours or less in the presence of a hydrazine or a hydrazide compound. It is a method for producing strontium titanate fine particles having a reaction step of reacting with and having a molar ratio of the hydrazine or hydrazide compound to the organic titanium acid ester (hydrazine or hydrazide compound / organic titanium acid ester) of 10 to 75. ..
  • the method for producing strontium titanate fine particles of the present invention is a mixing step of mixing an organic titanium acid ester and a hydrazine or a hydrazide compound in a solvent to obtain a mixed solution, and an adjusting step of adjusting the pH of the mixed solution to 12 or more. , And it is preferable to have the above reaction step.
  • the polyhydric alcohol is preferably ethylene glycol.
  • the organic titanium acid ester is preferably titanium lactate.
  • the strontium compound is preferably at least one selected from strontium acetate and strontium formate.
  • the aminosilane compound is preferably 3-aminopropyltriethoxysilane.
  • the method for producing strontium titanate fine particles of the present invention can produce strontium titanate fine particles having excellent dispersibility under simple conditions.
  • the present invention presents the organic titanium acid ester and the strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or more and 250 ° C. or less, and a reaction time of 0.5 hours or more and 2 hours or less in the presence of a hydrazine or a hydrazide compound. It is a method for producing strontium titanate fine particles having a reaction step of reacting with and having a molar ratio of the hydrazine or hydrazide compound to the organic titanium acid ester (hydrazine or hydrazide compound / organic titanium acid ester) of 10 to 75. .. First, various materials used in the method for producing strontium titanate fine particles of the present invention will be described.
  • organic titanium acid ester examples include tetraethyl titanate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, and polymers thereof, titanium acetyl titanate, and polytitanium acetylacetonate.
  • hydrazide compound examples include 1-monomethyl hydrazine, 1,1-dimethyl hydrazine, 1-ethyl-2-methyl hydrazine, adipic acid dihydrazide, dihydrazide oxalic acid, dihydrazide malonate, dihydrazide succinate, dihydrazide glutarate, and isophthalate.
  • examples thereof include acid dihydrazide, sebasic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, andaconic acid dihydrazide.
  • hydrazine is preferable because it is relatively easy to handle and has an excellent effect of controlling the shape of the obtained strontium titanate fine particles.
  • the hydrazine or hydrazide compound may be hydrogenated.
  • the content of the hydrazine or the hydrazide compound is preferably 10 to 75 and preferably 30 to 65 in terms of the molar ratio (hydrazine or hydrazide compound / organic titanium acid ester) to the organic titanium acid ester.
  • the shape of the obtained strontium titanate fine particles can be controlled.
  • strontium compound examples include strontium nitrate, strontium hydroxide, strontium carbonate, strontium peroxide, strontium formate, strontium acetate, strontium lactate, strontium oxalate, strontium chloride, strontium fluoride, strontium iodide, strontium bromide, and chloric acid.
  • strontium, strontium iodate, strontium perchlorate and the like may be used as hydrates. Among them, at least one selected from strontium acetate and strontium formate is preferable, and strontium acetate is more preferable, from the viewpoint of hydrophilicity.
  • the molar ratio (strontium compound / organic titanium acid ester) to the organic titanium acid ester is preferably 1.0 or more. Within the above range, the progress of crystallization can be suitably controlled. Further, from the viewpoint of reducing raw material costs, the molar ratio (strontium compound / organic titanium acid ester) is more preferably 2.0 or less.
  • solvent Ion-exchanged water is preferably used as the solvent used in the method for producing strontium titanate fine particles of the present invention. Moreover, it is preferable that the solvent contains a polyhydric alcohol.
  • polyhydric alcohol examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, butanediol, pentanediol, hexanediol, heptanediol, nonanediol, decanediol, and neopentyl glycol.
  • dihydric alcohols and trihydric or higher polyhydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol.
  • At least one selected from ethylene glycol, propylene glycol, diethylene glycol, and 1,3-propanediol from the viewpoint of adjusting the particle size of the obtained strontium titanate fine particles and maintaining suitable dispersibility in the reaction system.
  • ethylene glycol is more preferable.
  • the content of the polyhydric alcohol is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and even more preferably 7 to 12% by mass with respect to the total amount of the solvent. ..
  • PH regulator In the method for producing strontium titanate fine particles of the present invention, it is preferable to adjust the pH using a pH adjuster.
  • the pH adjuster include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide and the like. Of these, potassium hydroxide is preferable from the viewpoint of solubility in the above solvent.
  • the pH is set to 12 or more from the viewpoint of controlling the reaction rate and the shape of the obtained strontium titanate fine particles.
  • the pH is preferably 12.5 or higher, more preferably 13 or higher, and even more preferably 13.5 or higher.
  • the content of the pH adjuster is not limited and may be appropriately added according to the target pH.
  • the reaction step is preferably carried out in the presence of the aminosilane compound.
  • the average particle size of the obtained strontium titanate fine particles can be further reduced, and the dispersibility can be more preferably imparted.
  • aminosilane compound examples include 3-aminopropyltrimethoxysilane, 3-aminopropylethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, and N-2- (aminoethyl) -3-aminopropyl.
  • examples thereof include trimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane. Of these, 3-aminopropyltriethoxysilane is preferable.
  • the content of the aminosilane compound is preferably 0.003 to 0.025, preferably 0.004 to 0.019, in terms of molar ratio (aminosilane compound / hydrazine or hydrazide compound) to the hydrazine or hydrazine compound. Is more preferable, and 0.007 to 0.015 is even more preferable.
  • amphoteric compound examples include saturation of propionic acid, butyric acid, valeric acid, caproic acid, capric acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, linolenic acid and the like.
  • Saturated fatty acids and the like can be mentioned.
  • the method for producing strontium titanate fine particles of the present invention comprises an organic strontium ester and a strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or higher and 250 ° C. or lower, and a reaction time of 0.5 hours or more and 2 hours or less. It has a reaction step of reacting with.
  • the method for producing strontium titanate fine particles of the present invention is, for example, a mixing step of mixing an organic titanium acid ester and a hydrazine or a hydrazide compound in a solvent to obtain a mixed solution, and adjusting the pH of the mixed solution to 12 or more. It is preferable to have an adjustment step and the above reaction step.
  • the mixing step is a step of adding an organic titanium acid ester and a hydrazine or a hydrazide compound to the solvent. It is presumed that hydrazine is coordinated to the organic titanium acid ester by the above mixing step.
  • the method of adding various materials is not particularly limited, and addition, stirring and the like may be performed by a well-known method.
  • the pH is adjusted.
  • the reaction rate and the shape of the obtained strontium titanate fine particles can be suitably controlled.
  • the increase in the average particle size of the organic titanium acid ester coordinated with hydrazine can be controlled by the above mixing step, and as a result, the average particle size of the obtained strontium titanate fine particles can be controlled in a suitable range.
  • the pH is preferably adjusted using the above pH adjuster. When the aminosilane compound is added, it is preferable to add it together with the pH adjusting agent in the adjusting step.
  • the organic titanic acid ester is reacted with the strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or more and 250 ° C. or less, and a reaction time of 0.5 hours or more and 2 hours or less.
  • the reaction temperature is 150 ° C. or higher and 250 ° C. or lower. If the reaction temperature is less than 150 ° C., the reaction does not proceed and the desired strontium titanate fine particles cannot be obtained. If the reaction temperature exceeds 250 ° C., the reaction efficiency decreases and the obtained strontium titanate fine particles become large. And the dispersibility is reduced.
  • the reaction temperature is preferably 180 to 250 ° C, more preferably 200 to 240 ° C.
  • the reaction time is 0.5 hours or more and 2 hours or less. If the reaction time is less than 0.5 hours, the reaction does not proceed and the desired strontium titanate fine particles cannot be obtained. If the reaction time exceeds 2 hours, the reaction efficiency is lowered and the obtained strontium titanate fine particles are obtained. Increases and the dispersibility decreases.
  • the reaction time is preferably 1 to 2 hours.
  • the pressure for the reaction may be, for example, about 2 to 5 MPa, and it is not necessary to apply a pressure exceeding 10 MPa.
  • the method for carrying out the above reaction step is not particularly limited, and any method that satisfies the above conditions may be used.
  • a pressure reaction vessel or the like can be used.
  • strontium titanate fine particles The strontium titanate fine particles obtained by the method for producing strontium titanate fine particles of the present invention have the following properties.
  • the strontium titanate fine particles preferably have a spherical particle shape.
  • the spherical shape means not only a true sphere but also an elliptical shape, a cylinder shape, a bale shape (a shape in which the corners of the cylinder are rounded), and the like.
  • the circularity of the strontium titanate fine particles is 0.900 to 1.000.
  • the shape of the strontium titanate fine particles can be confirmed, for example, by observing with a transmission electron microscope (“JEM-1011” manufactured by JEOL Ltd.) at an observation magnification of 300,000 times.
  • the circularity is an average value excluding those having a specific shape clearly different from the spherical shape among the fine particles appearing in the image taken by the transmission electron microscope.
  • the strontium titanate fine particles preferably have an average particle diameter of 10 nm to 30 nm, and more preferably 14 nm to 25 nm. By having such an average particle size, it is possible to have excellent dispersibility.
  • the average particle size is determined by dissolving strontium titanate fine particles in methanol to obtain a dispersion, then putting the obtained dispersion into a measuring cell, and using a laser diffraction / scattering particle size distribution measuring machine (manufactured by Nikkiso Co., Ltd.). , "Microtrack MT3300EXII”) means the average particle size (D50).
  • the strontium titanate fine particles have excellent dispersibility.
  • dispersibility means that 50 mg of strontium titanate fine particles are dissolved in 50 mL of methanol to obtain a dispersion, the obtained dispersion is placed in a screw tube bottle, and black paper is placed on the back surface to disperse the dispersion.
  • white turbidity occurs.
  • white turbidity does not occur, it can be evaluated as having excellent dispersibility, and can be suitably applied to, for example, a material having a high refractive index.
  • the strontium titanate fine particles preferably have good crystallinity.
  • the crystallinity of the strontium titanate fine particles is such that the crystallite size calculated by the X-ray diffractometer is the same as the particle size observed with the transmission electron microscope [the ratio of the particle size (with the transmission electron microscope). If the observed particle size / crystallite size calculated by the X-ray diffractometer) is 0.9 to 1.0], it is judged that the crystallinity is good, and if it is small or no crystal is confirmed, it is judged to be defective. ..
  • the strontium titanate fine particles preferably have a hydrazine or hydrazide compound content of 0.1% by mass to 60% by mass with respect to the strontium titanate fine particles. With such a content, the dispersibility becomes good.
  • Example 1 Add 3.0 g of purified water and 3.0 g of hydrated hydrazine (manufactured by Nippon Carbide Industries) to 0.584 g of titanium lactate (organic TC-310, component concentration 44 wt%, manufactured by Matsumoto Fine Chemical Co., Ltd.) to make a yellow transparent solution. bottom. Then, a solution prepared with 0.48 g of potassium hydroxide, 0.432 g of ethylene glycol, and 5.088 g of purified water was added to the above yellow transparent solution to obtain a cloudy solution.
  • a solution prepared with 0.48 g of potassium hydroxide, 0.432 g of ethylene glycol, and 5.088 g of purified water was added to the above yellow transparent solution to obtain a cloudy solution.
  • Separation and purification was completed by repeating the operation of preparing a redispersion solution of the fine particles with purified water, centrifuging and precipitating the fine particles three times.
  • the obtained fine particles were collected and observed with an X-ray diffractometer (“MiniFlex600-C” manufactured by Rigaku Co., Ltd.). As a result, it was confirmed that the fine particles were strontium titanate.
  • Strontium titanate fine particles were produced in the same manner as in Examples except that the blending amounts of various materials and the reaction conditions were changed as shown in Table 1.
  • 3-aminopropyltriethoxysilane was added together with the pH adjuster (potassium hydroxide).
  • the obtained fine particles were collected and observed with an X-ray diffractometer (“MiniFlex600-C” manufactured by Rigaku Co., Ltd.). As a result, they were fine particles of strontium titanate in Examples 2 to 8 and Comparative Example 4. It was confirmed. On the other hand, in Comparative Examples 1 to 3, 5 and 6, the reaction did not proceed and strontium titanate fine particles could not be obtained.
  • Average particle size 50 mg of the fine particles obtained in Examples and Comparative Examples were dissolved in 50 mL of methanol to obtain a dispersion. The obtained dispersion was placed in a measuring cell, and the average particle size (D50) was measured with a laser diffraction / scattering type particle size distribution measuring machine (“Microtrack MT3300EXII” manufactured by Nikkiso Co., Ltd.).
  • the strontium titanate fine particles obtained in the examples had a spherical particle shape and an average particle diameter of 14 nm to 30 nm, and were excellent in crystallinity and dispersibility.
  • strontium titanate fine particles having a small average particle size and excellent dispersibility could be obtained.
  • Example 7 using the phosphoric acid ester titanium complex and Example 8 using propylene glycol as the solvent the transparency of the dispersion was slightly lower than that of the other examples, and was higher than that of the other examples. The result was that the dispersibility was slightly low.
  • Comparative Examples 1 to 3, 5 and 6 the reaction did not proceed and strontium titanate fine particles could not be obtained. Further, the fine particles obtained in Comparative Examples 1 to 3 which did not contain hydrazine or a hydrazide compound or whose addition amount was not in the predetermined range had a large average particle size and were inferior in dispersibility (the dispersion liquid became cloudy). Was). Further, the strontium titanate fine particles obtained in Comparative Example 4 in which the reaction temperature was not in the predetermined range had insufficient crystallinity. Further, the fine particles obtained in Comparative Example 5 in which the reaction time was too long had a large average particle size and were inferior in dispersibility (the dispersion liquid was cloudy). Further, in Comparative Example 6 in which the reaction time was long and the pH was low, the reaction did not proceed and fine particles could not be obtained.
  • the method for producing strontium titanate fine particles of the present invention is, for example, a high refractive index agent, a thermoelectric conversion material, a photocatalyst, an ionic conductive material, a dielectric material, a magnetic material, a catalyst material, an oxygen electrode material, a piezoelectric material, and a pyroelectricity. It is useful in that it is possible to obtain strontium titanate fine particles that can be used as functional materials such as materials, nonlinear optical materials, and fillers.

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Abstract

Provided is a method for producing strontium titanate microparticles, the method making it possible to produce, under simple conditions, strontium titanate microparticles having exceptional dispersibility. A method for producing strontium titanate microparticles, the method having a reaction step for reacting an organic titanic acid ester and a strontium compound at a pH of 12 or higher, a reaction temperature of 150-250°C (inclusive), and a reaction time of 0.5-2 hours (inclusive) in the presence of hydrazine or a hydrazide compound, the molar ratio (hydrazine or hydrazide compound/organic titanic acid ester) of the hydrazine or hydrazide compound to the organic titanic acid ester being 10-75.

Description

チタン酸ストロンチウム微粒子の製造方法Method for manufacturing strontium titanate fine particles
本発明は、チタン酸ストロンチウム微粒子の製造方法に関する。 The present invention relates to a method for producing strontium titanate fine particles.
チタン酸ストロンチウム（ＳｒＴｉＯ３）は、誘電特性、熱電特性、光触媒能、高屈折率性等を有することから、機能性材料として様々な用途への展開が期待されている。 Since strontium titanate (SrTiO 3 ) has dielectric properties, thermoelectric properties, photocatalytic activity, high refractive index properties, etc., it is expected to be used in various applications as a functional material.
例えば、特許文献１では、平均粒子径が５０ｎｍ以下、平均アスペクト比が１．０～１．２、屈折率が１．８～２．６である、チタン酸ストロンチウムが、高屈折率性を有することが開示されている。また、特許文献１では、チタン酸ストロンチウムを、高屈折率性を付与する成分として用いる場合には、塗膜中において凝集しない高い分散性が必要とされることが開示されている。 For example, in Patent Document 1, strontium titanate having an average particle size of 50 nm or less, an average aspect ratio of 1.0 to 1.2, and a refractive index of 1.8 to 2.6 has a high refractive index. Is disclosed. Further, Patent Document 1 discloses that when strontium titanate is used as a component that imparts high refractive index property, high dispersibility that does not aggregate in the coating film is required.
また、チタン酸ストロンチウムの製造方法として、例えば、特許文献２では、オレイン酸及びヒドラジンの存在下で、チタンペルオキソ乳酸アンモニウムと水酸化ストロンチウムとを２００℃の恒温槽中で２４時間加熱処理を行ってチタン酸ストロンチウムを製造する方法が開示されている。
しかしながら、特許文献２に記載の方法では、チタン酸ストロンチウムの製造に際して時間が掛かりすぎるため、より簡便に製造できる方法が求められていた。 Further, as a method for producing strontium titanate, for example, in Patent Document 2, titanium peroxoammonium lactate and strontium hydroxide are heat-treated in a constant temperature bath at 200 ° C. for 24 hours in the presence of oleic acid and hydrazine. A method for producing strontium titanate is disclosed.
However, in the method described in Patent Document 2, it takes too much time to produce strontium titanate, so that a method that can be produced more easily has been required.
国際公開第２０１１／００４７５０号International Publication No. 2011/004750 特開２０１１－０６８５００号公報Japanese Unexamined Patent Publication No. 2011-068500
本発明は、簡便な条件で、分散性に優れるチタン酸ストロンチウム微粒子を製造することができるチタン酸ストロンチウム微粒子の製造方法を提供することを目的とする。 An object of the present invention is to provide a method for producing strontium titanate fine particles, which can produce strontium titanate fine particles having excellent dispersibility under simple conditions.
本発明者らは、チタン酸ストロンチウム微粒子の製造方法について鋭意検討したところ、ヒドラジン又はヒドラジド化合物を特定量含み、所定の条件（温度及び反応時間）で有機チタン酸エステルと、ストロンチウム化合物とを反応させることにより、従来よりも短い反応時間で、分散性に優れるチタン酸ストロンチウム微粒子を製造することができることを見出した。 The present inventors have diligently studied a method for producing strontium titanate fine particles, and found that a specific amount of hydrazine or hydrazide compound is contained, and the organic titanium acid ester is reacted with the strontium compound under predetermined conditions (temperature and reaction time). As a result, it has been found that strontium titanate fine particles having excellent dispersibility can be produced in a shorter reaction time than before.
本発明は、ヒドラジン又はヒドラジド化合物の存在下、ｐＨが１２以上、反応温度が１５０℃以上２５０℃以下、反応時間が０．５時間以上２時間以下の条件で、有機チタン酸エステルと、ストロンチウム化合物とを反応させる反応工程を有し、上記有機チタン酸エステルに対する上記ヒドラジン又はヒドラジド化合物のモル比（ヒドラジン又はヒドラジド化合物／有機チタン酸エステル）が１０～７５であるチタン酸ストロンチウム微粒子の製造方法である。
本発明のチタン酸ストロンチウム微粒子の製造方法は、有機チタン酸エステルと、ヒドラジン又はヒドラジド化合物とを溶媒中で混合し、混合液を得る混合工程、上記混合液のｐＨを１２以上に調整する調整工程、及び、上記反応工程を有することが好ましい。
本発明のチタン酸ストロンチウムの製造方法では、上記反応工程において、多価アルコールの存在下で行うことが好ましい。上記多価アルコールは、エチレングリコールであることが好ましい。
また、上記有機チタン酸エステルは、チタンラクテートであることが好ましい。
また、上記ストロンチウム化合物は、酢酸ストロンチウム、ギ酸ストロンチウムから選択される少なくとも一種であることが好ましい。
また、上記反応工程をアミノシラン化合物の存在下で行うことが好ましい。
また、上記アミノシラン化合物は、３－アミノプロピルトリエトキシシランであることが好ましい。 The present invention presents the organic titanium acid ester and the strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or more and 250 ° C. or less, and a reaction time of 0.5 hours or more and 2 hours or less in the presence of a hydrazine or a hydrazide compound. It is a method for producing strontium titanate fine particles having a reaction step of reacting with and having a molar ratio of the hydrazine or hydrazide compound to the organic titanium acid ester (hydrazine or hydrazide compound / organic titanium acid ester) of 10 to 75. ..
The method for producing strontium titanate fine particles of the present invention is a mixing step of mixing an organic titanium acid ester and a hydrazine or a hydrazide compound in a solvent to obtain a mixed solution, and an adjusting step of adjusting the pH of the mixed solution to 12 or more. , And it is preferable to have the above reaction step.
In the method for producing strontium titanate of the present invention, it is preferable to carry out the above reaction step in the presence of a polyhydric alcohol. The polyhydric alcohol is preferably ethylene glycol.
Further, the organic titanium acid ester is preferably titanium lactate.
Further, the strontium compound is preferably at least one selected from strontium acetate and strontium formate.
Further, it is preferable to carry out the above reaction step in the presence of the aminosilane compound.
The aminosilane compound is preferably 3-aminopropyltriethoxysilane.
本発明のチタン酸ストロンチウム微粒子の製造方法は、簡便な条件で、分散性に優れるチタン酸ストロンチウム微粒子を製造することができる。 The method for producing strontium titanate fine particles of the present invention can produce strontium titanate fine particles having excellent dispersibility under simple conditions.
本発明は、ヒドラジン又はヒドラジド化合物の存在下、ｐＨが１２以上、反応温度が１５０℃以上２５０℃以下、反応時間が０．５時間以上２時間以下の条件で、有機チタン酸エステルと、ストロンチウム化合物とを反応させる反応工程を有し、上記有機チタン酸エステルに対する上記ヒドラジン又はヒドラジド化合物のモル比（ヒドラジン又はヒドラジド化合物／有機チタン酸エステル）が１０～７５であるチタン酸ストロンチウム微粒子の製造方法である。
まずは、本発明のチタン酸ストロンチウム微粒子の製造方法に用いる各種材料について説明する。 The present invention presents the organic titanium acid ester and the strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or more and 250 ° C. or less, and a reaction time of 0.5 hours or more and 2 hours or less in the presence of a hydrazine or a hydrazide compound. It is a method for producing strontium titanate fine particles having a reaction step of reacting with and having a molar ratio of the hydrazine or hydrazide compound to the organic titanium acid ester (hydrazine or hydrazide compound / organic titanium acid ester) of 10 to 75. ..
First, various materials used in the method for producing strontium titanate fine particles of the present invention will be described.
（有機チタン酸エステル）
上記有機チタン酸エステルとしては、例えば、テトラエチルチタネート、テトライソプロピルチタネート、テトラノルマルブチルチタネート、ブチルチタネートダイマー、テトラ（２－エチルヘキシル）チタネート、およびこれらの重合物や、チタンアセチルチタネート、ポリチタンアセチルアセトネート、チタンオクチルグリシナート、チタンラクテート、チタンラクテートエチルエステル、チタントリエタノールアミネート、リン酸エステルチタン錯体等のチタンキレート化合物等が挙げられる。
なかでも、親水性の観点から、チタンラクテートが好ましい。 (Organic titanium acid ester)
Examples of the organic titanium acid ester include tetraethyl titanate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, and polymers thereof, titanium acetyl titanate, and polytitanium acetylacetonate. , Titanium octylglycinate, titanium lactate, titanium lactate ethyl ester, titanium triethanolaminate, titanium phosphate ester titanium complex and other titanium chelate compounds and the like.
Of these, titanium lactate is preferable from the viewpoint of hydrophilicity.
（ヒドラジン又はヒドラジド化合物）
上記ヒドラジド化合物としては、例えば、１－モノメチルヒドラジン、１，１－ジメチルヒドラジン、１－エチル－２－メチルヒドラジン、アジピン酸ジヒドラジド、シュウ酸ジヒドラジド、マロン酸ジヒドラジド、コハク酸ジヒドラジド、グルタル酸ジヒドラジド、イソフタル酸ジヒドラジド、セバシン酸ジヒドラジド、マレイン酸ジヒドラジド、フマル酸ジヒドラジド、イタコン酸ジヒドラジド等が挙げられる。
なかでも、扱いが比較的容易であり、得られるチタン酸ストロンチウム微粒子の形状を制御する効果に優れる点からヒドラジンが好ましい。
上記ヒドラジン又はヒドラジド化合物は、水添の状態であってもよい。 (Hydrazine or hydrazide compound)
Examples of the hydrazide compound include 1-monomethyl hydrazine, 1,1-dimethyl hydrazine, 1-ethyl-2-methyl hydrazine, adipic acid dihydrazide, dihydrazide oxalic acid, dihydrazide malonate, dihydrazide succinate, dihydrazide glutarate, and isophthalate. Examples thereof include acid dihydrazide, sebasic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, andaconic acid dihydrazide.
Of these, hydrazine is preferable because it is relatively easy to handle and has an excellent effect of controlling the shape of the obtained strontium titanate fine particles.
The hydrazine or hydrazide compound may be hydrogenated.
上記ヒドラジン又はヒドラジド化合物の含有量としては、上記有機チタン酸エステルに対してモル比（ヒドラジン又はヒドラジド化合物／有機チタン酸エステル）が、１０～７５であり、３０～６５であることが好ましい。
上記範囲とすることにより、得られるチタン酸ストロンチウム微粒子の形状を制御することができる。 The content of the hydrazine or the hydrazide compound is preferably 10 to 75 and preferably 30 to 65 in terms of the molar ratio (hydrazine or hydrazide compound / organic titanium acid ester) to the organic titanium acid ester.
Within the above range, the shape of the obtained strontium titanate fine particles can be controlled.
（ストロンチウム化合物）
上記ストロンチウム化合物としては、硝酸ストロンチウム、水酸化ストロンチウム、炭酸ストロンチウム、過酸化ストロンチウム、ギ酸ストロンチウム、酢酸ストロンチウム、乳酸ストロンチウム、シュウ酸ストロンチウム、塩化ストロンチウム、フッ化ストロンチウム、ヨウ化ストロンチウム、臭化ストロンチウム、塩素酸ストロンチウム、ヨウ素酸ストロンチウム、過塩素酸ストロンチウム等が挙げられる。これらは水和物として用いてもよい。
なかでも、親水性の観点から、酢酸ストロンチウム、ギ酸ストロンチウムから選択される少なくとも一種が好ましく、酢酸ストロンチウムがより好ましい。 (Strontium compound)
Examples of the strontium compound include strontium nitrate, strontium hydroxide, strontium carbonate, strontium peroxide, strontium formate, strontium acetate, strontium lactate, strontium oxalate, strontium chloride, strontium fluoride, strontium iodide, strontium bromide, and chloric acid. Examples thereof include strontium, strontium iodate, strontium perchlorate and the like. These may be used as hydrates.
Among them, at least one selected from strontium acetate and strontium formate is preferable, and strontium acetate is more preferable, from the viewpoint of hydrophilicity.
上記ストロンチウム化合物の含有量としては、上記有機チタン酸エステルに対してモル比（ストロンチウム化合物／有機チタン酸エステル）が、１．０以上であることが好ましい。
上記範囲とすることにより、結晶化の進行を好適に制御することができる。
また、原材料費を抑える観点から、上記モル比（ストロンチウム化合物／有機チタン酸エステル）は、２．０以下であることがより好ましい。 As for the content of the strontium compound, the molar ratio (strontium compound / organic titanium acid ester) to the organic titanium acid ester is preferably 1.0 or more.
Within the above range, the progress of crystallization can be suitably controlled.
Further, from the viewpoint of reducing raw material costs, the molar ratio (strontium compound / organic titanium acid ester) is more preferably 2.0 or less.
（溶媒）
本発明のチタン酸ストロンチウム微粒子の製造方法に用いる溶媒としては、イオン交換水を用いることが好ましい。
また、上記溶媒は、多価アルコールを含有することが好ましい。 (solvent)
Ion-exchanged water is preferably used as the solvent used in the method for producing strontium titanate fine particles of the present invention.
Moreover, it is preferable that the solvent contains a polyhydric alcohol.
上記多価アルコールとしては、エチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、１，３－プロパンジオール、ブタンジオール、ペンタンジオール、ヘキサンジオール、ヘプタンジオール、ノナンジオール、デカンジオール、及びネオペンチルグリコール等の２価アルコールや、グリセリン、トリメチロールプロパン、及びペンタエリスリトール等の３価以上の多価アルコールが挙げられる。
なかでも、得られるチタン酸ストロンチウム微粒子の粒子径を調整する観点、反応系において分散性を好適に維持する観点から、エチレングリコール、プロピレングリコール、ジエチレングリコール、１，３－プロパンジオールから選択される少なくとも一種が好ましく、エチレングリコールがより好ましい。 Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, butanediol, pentanediol, hexanediol, heptanediol, nonanediol, decanediol, and neopentyl glycol. Examples thereof include dihydric alcohols and trihydric or higher polyhydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol.
Among them, at least one selected from ethylene glycol, propylene glycol, diethylene glycol, and 1,3-propanediol from the viewpoint of adjusting the particle size of the obtained strontium titanate fine particles and maintaining suitable dispersibility in the reaction system. Is preferable, and ethylene glycol is more preferable.
上記多価アルコールの含有量は、上記溶媒の全量に対して１～２０質量％であることが好ましく、３～１５質量％であることがより好ましく、７～１２質量％であることが更に好ましい。 The content of the polyhydric alcohol is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and even more preferably 7 to 12% by mass with respect to the total amount of the solvent. ..
（ｐＨ調整剤）
本発明のチタン酸ストロンチウム微粒子の製造方法では、ｐＨ調整剤を用いてｐＨを調整することが好ましい。
上記ｐＨ調整剤としては、水酸化リチウム、水酸化ナトリウム、水酸化カリウム、水酸化カルシウム、水酸化アンモニウム等が挙げられる。
なかでも、上記溶媒への溶解性の観点から、水酸化カリウムが好ましい。 (PH regulator)
In the method for producing strontium titanate fine particles of the present invention, it is preferable to adjust the pH using a pH adjuster.
Examples of the pH adjuster include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide and the like.
Of these, potassium hydroxide is preferable from the viewpoint of solubility in the above solvent.
ｐＨを調整する際には、反応速度と得られるチタン酸ストロンチウム微粒子の形状を制御する観点から、ｐＨを１２以上にする。
ｐＨは１２．５以上であることが好ましく、１３以上であることがより好ましく、１３．５以上であることが更に好ましい。
上記ｐＨ調整剤の含有量は限定されず、目的とするｐＨに応じて適宜加えればよい。 When adjusting the pH, the pH is set to 12 or more from the viewpoint of controlling the reaction rate and the shape of the obtained strontium titanate fine particles.
The pH is preferably 12.5 or higher, more preferably 13 or higher, and even more preferably 13.5 or higher.
The content of the pH adjuster is not limited and may be appropriately added according to the target pH.
（アミノシラン化合物）
上記反応工程は、アミノシラン化合物の存在下で行うことが好ましい。
上記反応工程をアミノシラン化合物の存在下で行うことにより、得られるチタン酸ストロンチウム微粒子の平均粒子径を更に小さくすることができ、分散性をより好適に付与することができる。 (Aminosilane compound)
The reaction step is preferably carried out in the presence of the aminosilane compound.
By performing the above reaction step in the presence of the aminosilane compound, the average particle size of the obtained strontium titanate fine particles can be further reduced, and the dispersibility can be more preferably imparted.
アミノシラン化合物としては、３－アミノプロピルトリメトキシシラン、３－アミノプロピルエトキシシラン、Ｎ－２－（アミノエチル）－３－アミノプロピルメチルジメトキシシラン、Ｎ－２－（アミノエチル）－３－アミノプロピルトリメトキシシラン、Ｎ－フェニル－３－アミノプロピルトリメトキシシランなどが挙げられる。
なかでも、３－アミノプロピルトリエトキシシランであることが好ましい。 Examples of the aminosilane compound include 3-aminopropyltrimethoxysilane, 3-aminopropylethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, and N-2- (aminoethyl) -3-aminopropyl. Examples thereof include trimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane.
Of these, 3-aminopropyltriethoxysilane is preferable.
上記アミノシラン化合物の含有量は、ヒドラジン又はヒドラジド化合物に対してモル比（アミノシラン化合物／ヒドラジン又はヒドラジド化合物）で０．００３～０．０２５であることが好ましく、０．００４～０．０１９であることがより好ましく、０．００７～０．０１５であることが更に好ましい。 The content of the aminosilane compound is preferably 0.003 to 0.025, preferably 0.004 to 0.019, in terms of molar ratio (aminosilane compound / hydrazine or hydrazide compound) to the hydrazine or hydrazine compound. Is more preferable, and 0.007 to 0.015 is even more preferable.
（その他）
本発明のチタン酸ストロンチウム微粒子の製造方法では、両親媒性化合物を加えなくてもよい。
従来のチタン酸ストロンチウム微粒子の製造方法では、両親媒性化合物の存在下で反応を進行させることにより、粒子サイズ・形状が高度に制御し、粒子の分散性を付与していた。
一方で、本発明のチタン酸ストロンチウム微粒子の製造方法において、上記両親媒性化合物を加えると、系中で不均一に分散してしまい、その結果、得られるチタン酸ストロンチウム微粒子の平均粒子径が大きくなってしまう。
上記両親媒性化合物としては、例えば、プロピオン酸、酪酸、吉草酸、カプロン酸、カプリル酸、カプリン酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、アラキジン酸、ベヘン酸、リグノセリン酸等の飽和脂肪酸類、α－リノレン酸、ステアリドン酸、エイコサペンタエン酸、ドコサヘキサエン酸、リノール酸、γ－リノレン酸、ジホモ－γ－リノレン酸、アラキドン酸、オレイン酸、エライジン酸、エルカ酸、ネルボン酸等の不飽和脂肪酸等が挙げられる。 (others)
In the method for producing strontium titanate fine particles of the present invention, it is not necessary to add an amphipathic compound.
In the conventional method for producing strontium titanate fine particles, the particle size and shape are highly controlled by advancing the reaction in the presence of an amphipathic compound, and the dispersibility of the particles is imparted.
On the other hand, in the method for producing strontium titanate fine particles of the present invention, when the above amphoteric compound is added, the particles are dispersed non-uniformly in the system, and as a result, the average particle size of the obtained strontium titanate fine particles is large. turn into.
Examples of the amphoteric compound include saturation of propionic acid, butyric acid, valeric acid, caproic acid, capric acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, linolenic acid and the like. Non-fatty acids, α-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, linolenic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid, oleic acid, ellaic acid, erucic acid, nervonic acid, etc. Saturated fatty acids and the like can be mentioned.
（製造方法）
本発明のチタン酸ストロンチウム微粒子の製造方法は、ｐＨが１２以上、反応温度が１５０℃以上２５０℃以下、反応時間が０．５時間以上２時間以下の条件で、有機チタン酸エステルと、ストロンチウム化合物とを反応させる反応工程を有する。
本発明のチタン酸ストロンチウム微粒子の製造方法は、例えば、有機チタン酸エステルと、ヒドラジン又はヒドラジド化合物とを溶媒中で混合し、混合液を得る混合工程、上記混合液のｐＨを１２以上に調整する調整工程、及び、上記反応工程を有することが好ましい。 (Production method)
The method for producing strontium titanate fine particles of the present invention comprises an organic strontium ester and a strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or higher and 250 ° C. or lower, and a reaction time of 0.5 hours or more and 2 hours or less. It has a reaction step of reacting with.
The method for producing strontium titanate fine particles of the present invention is, for example, a mixing step of mixing an organic titanium acid ester and a hydrazine or a hydrazide compound in a solvent to obtain a mixed solution, and adjusting the pH of the mixed solution to 12 or more. It is preferable to have an adjustment step and the above reaction step.
上記混合工程は、溶媒中に有機チタン酸エステルと、ヒドラジン又はヒドラジド化合物とを加える工程である。
上記混合工程により、有機チタン酸エステルにヒドラジンが配位されると推測される。
上記混合工程において、各種材料を加える方法は特に限定されず、周知の方法により添加、攪拌等を行えばよい。 The mixing step is a step of adding an organic titanium acid ester and a hydrazine or a hydrazide compound to the solvent.
It is presumed that hydrazine is coordinated to the organic titanium acid ester by the above mixing step.
In the above mixing step, the method of adding various materials is not particularly limited, and addition, stirring and the like may be performed by a well-known method.
上記調製工程では、ｐＨの調整を行う。これにより、反応速度と、得られるチタン酸ストロンチウム微粒子の形状を好適に制御することができる。
また、上記混合工程によりヒドラジンが配位した有機チタン酸エステルの平均粒子径の増大を制御し、その結果、得られるチタン酸ストロンチウム微粒子の平均粒子径を好適な範囲に制御できると考えられる。
なお、ｐＨの調製は、上記ｐＨ調整剤を用いて行うことが好ましい。
また、上記アミノシラン化合物を添加する場合は、上記ｐＨ調整剤とともに、上記調整工程にて添加することが好ましい。 In the above preparation step, the pH is adjusted. Thereby, the reaction rate and the shape of the obtained strontium titanate fine particles can be suitably controlled.
Further, it is considered that the increase in the average particle size of the organic titanium acid ester coordinated with hydrazine can be controlled by the above mixing step, and as a result, the average particle size of the obtained strontium titanate fine particles can be controlled in a suitable range.
The pH is preferably adjusted using the above pH adjuster.
When the aminosilane compound is added, it is preferable to add it together with the pH adjusting agent in the adjusting step.
チタン酸ストロンチウム微粒子は、水が多く存在すると結晶成長が早くなる一方、溶媒の疎水性が高くなると、チタン酸ストロンチウム微粒子表面が親水性であるために凝集を促進してしまう。
一方で、上記多価アルコールは、親水性でありながら結晶成長を抑制する効果を有するため、上記調製工程において加えることが好ましい。
上記調製工程において、各種材料を加える方法は特に限定されず、周知の方法により添加、攪拌等を行えばよい。 Crystal growth of strontium titanate fine particles becomes faster in the presence of a large amount of water, while when the hydrophobicity of the solvent becomes high, the surface of the strontium titanate fine particles is hydrophilic and promotes aggregation.
On the other hand, since the polyhydric alcohol has an effect of suppressing crystal growth while being hydrophilic, it is preferable to add it in the preparation step.
In the above preparation step, the method of adding various materials is not particularly limited, and addition, stirring and the like may be performed by a well-known method.
上記反応工程では、ｐＨが１２以上、反応温度が１５０℃以上２５０℃以下、反応時間が０．５時間以上２時間以下の条件で、上記有機チタン酸エステルと、上記ストロンチウム化合物とを反応させる。 In the above reaction step, the organic titanic acid ester is reacted with the strontium compound under the conditions of a pH of 12 or more, a reaction temperature of 150 ° C. or more and 250 ° C. or less, and a reaction time of 0.5 hours or more and 2 hours or less.
上記反応温度は、１５０℃以上２５０℃以下である。
上記反応温度が１５０℃未満であると、反応が進行せず、目的とするチタン酸ストロンチウム微粒子が得られず、２５０℃を超えると、反応効率が低下するとともに得られるチタン酸ストロンチウム微粒子が大きくなって分散性が低下する。
上記反応温度は、１８０～２５０℃であることが好ましく、２００～２４０℃であることがより好ましい。 The reaction temperature is 150 ° C. or higher and 250 ° C. or lower.
If the reaction temperature is less than 150 ° C., the reaction does not proceed and the desired strontium titanate fine particles cannot be obtained. If the reaction temperature exceeds 250 ° C., the reaction efficiency decreases and the obtained strontium titanate fine particles become large. And the dispersibility is reduced.
The reaction temperature is preferably 180 to 250 ° C, more preferably 200 to 240 ° C.
上記反応時間は、０．５時間以上２時間以下である。
上記反応時間が、０．５時間未満であると、反応が進行せず、目的とするチタン酸ストロンチウム微粒子が得られず、２時間を超えると、反応効率が低下するとともに得られるチタン酸ストロンチウム微粒子が大きくなって分散性が低下する。
上記反応時間は、１～２時間であることが好ましい。 The reaction time is 0.5 hours or more and 2 hours or less.
If the reaction time is less than 0.5 hours, the reaction does not proceed and the desired strontium titanate fine particles cannot be obtained. If the reaction time exceeds 2 hours, the reaction efficiency is lowered and the obtained strontium titanate fine particles are obtained. Increases and the dispersibility decreases.
The reaction time is preferably 1 to 2 hours.
反応させる際の圧力としては、例えば、２～５ＭＰａ程度であればよく、１０ＭＰａを超えるような圧力を加える必要はない。 The pressure for the reaction may be, for example, about 2 to 5 MPa, and it is not necessary to apply a pressure exceeding 10 MPa.
上記反応工程を行う方法としては特に限定されず、上記条件を満たす方法であればよい。
例えば、圧力反応容器等を用いることができる。 The method for carrying out the above reaction step is not particularly limited, and any method that satisfies the above conditions may be used.
For example, a pressure reaction vessel or the like can be used.
（チタン酸ストロンチウム微粒子）
本発明のチタン酸ストロンチウム微粒子の製造方法により得られたチタン酸ストロンチウム微粒子は、以下の性質を有する。 (Strontium titanate fine particles)
The strontium titanate fine particles obtained by the method for producing strontium titanate fine particles of the present invention have the following properties.
上記チタン酸ストロンチウム微粒子は、粒子形状が球形であることが好ましい。
ここで球形とは、真球だけでなく、楕円体形、円柱形、俵形（円柱の角を丸めた形状）等を含むものをいう。
具体的には、上記チタン酸ストロンチウム微粒子の円形度が、０．９００～１．０００であることを意味する。
なお、上記チタン酸ストロンチウム微粒子の形状は、例えば、透過型電子顕微鏡（日本電子社製「ＪＥＭ－１０１１」）により観察倍率３０万倍にて観察することにより確認することができる。
また、上記チタン酸ストロンチウム微粒子の円形度は、透過型電子顕微鏡で撮影した画像の微粒子の面積をＳ、周囲長をＬとすると、円形度＝４πＳ／Ｌ２で計算できる。
なお、上記円形度は、透過型電子顕微鏡で撮影した画像に現れる微粒子のうち、上記球形とは明らかに異なる特異的な形状を有するものを除いた平均値である。 The strontium titanate fine particles preferably have a spherical particle shape.
Here, the spherical shape means not only a true sphere but also an elliptical shape, a cylinder shape, a bale shape (a shape in which the corners of the cylinder are rounded), and the like.
Specifically, it means that the circularity of the strontium titanate fine particles is 0.900 to 1.000.
The shape of the strontium titanate fine particles can be confirmed, for example, by observing with a transmission electron microscope (“JEM-1011” manufactured by JEOL Ltd.) at an observation magnification of 300,000 times.
Further, the circularity of the strontium titanate fine particles can be calculated by circularity = 4πS / L 2 , where S is the area of the fine particles in the image taken by the transmission electron microscope and L is the peripheral length.
The circularity is an average value excluding those having a specific shape clearly different from the spherical shape among the fine particles appearing in the image taken by the transmission electron microscope.
上記チタン酸ストロンチウム微粒子は、平均粒子径が１０ｎｍ～３０ｎｍであることが好ましく、１４ｎｍ～２５ｎｍであることがより好ましい。
このような平均粒子径を有することにより、優れた分散性を有するものとすることができる。
なお、上記平均粒子径は、チタン酸ストロンチウム微粒子をメタノールに溶解させて分散液を得た後、得られた分散液を測定セルに入れ、レーザ回折・散乱型粒度分布測定機（日機装株式会社製、「マイクロトラックＭＴ３３００ＥＸＩＩ」）にて測定した平均粒子径（Ｄ５０）を意味する。 The strontium titanate fine particles preferably have an average particle diameter of 10 nm to 30 nm, and more preferably 14 nm to 25 nm.
By having such an average particle size, it is possible to have excellent dispersibility.
The average particle size is determined by dissolving strontium titanate fine particles in methanol to obtain a dispersion, then putting the obtained dispersion into a measuring cell, and using a laser diffraction / scattering particle size distribution measuring machine (manufactured by Nikkiso Co., Ltd.). , "Microtrack MT3300EXII") means the average particle size (D50).
上記チタン酸ストロンチウム微粒子は、優れた分散性を有する。
ここで分散性とは、チタン酸ストロンチウム微粒子５０ｍｇを、５０ｍＬのメタノールに溶解させて分散液を得た後、得られた分散液をスクリュー管瓶に入れ、背面に黒紙を設置して、分散液の状態を目視にて確認したときに、白濁を生じるか否かで判断することができる。白濁が生じない場合には、優れた分散性を有するものと評価することができ、例えば高屈折率材料等に好適に適用することができる。 The strontium titanate fine particles have excellent dispersibility.
Here, dispersibility means that 50 mg of strontium titanate fine particles are dissolved in 50 mL of methanol to obtain a dispersion, the obtained dispersion is placed in a screw tube bottle, and black paper is placed on the back surface to disperse the dispersion. When the state of the liquid is visually confirmed, it can be determined whether or not white turbidity occurs. When white turbidity does not occur, it can be evaluated as having excellent dispersibility, and can be suitably applied to, for example, a material having a high refractive index.
上記チタン酸ストロンチウム微粒子は、結晶性が良好であることが好ましい。
なお、上記チタン酸ストロンチウム微粒子の結晶性は、Ｘ線回折装置で算出される結晶子径が、透過型電子顕微鏡で観察した粒子径に対して、同じ[粒子径の比率（透過型電子顕微鏡で観察した粒子径／Ｘ線回折装置で算出される結晶子径）が０．９～１．０]であれば結晶性良好と判断し、小さい場合や結晶が確認されない場合は、不良と判断する。 The strontium titanate fine particles preferably have good crystallinity.
The crystallinity of the strontium titanate fine particles is such that the crystallite size calculated by the X-ray diffractometer is the same as the particle size observed with the transmission electron microscope [the ratio of the particle size (with the transmission electron microscope). If the observed particle size / crystallite size calculated by the X-ray diffractometer) is 0.9 to 1.0], it is judged that the crystallinity is good, and if it is small or no crystal is confirmed, it is judged to be defective. ..
上記チタン酸ストロンチウム微粒子は、ヒドラジン又はヒドラジド化合物の含有量が上記チタン酸ストロンチウム微粒子に対して０．１質量％～６０質量％であることが好ましい。
このような含有量であることにより、分散性が良好となる。 The strontium titanate fine particles preferably have a hydrazine or hydrazide compound content of 0.1% by mass to 60% by mass with respect to the strontium titanate fine particles.
With such a content, the dispersibility becomes good.
以下に実施例を掲げて本発明をさらに詳細に説明するが、本発明はこれらの実施例のみに限定されるものではない。なお、特に断りのない限り、「％」は「質量％」を意味し、「部」は「質量部」を意味するものである。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "part" means "part by mass".
実施例及び比較例で用いた材料は以下の通りである。
（有機チタン酸エステル）
チタンラクテート（オルガチックス　ＴＣ－３１０、成分濃度４４ｗｔ％、マツモトファインケミカル社製）
リン酸エステルチタン錯体（オルガチックス　ＴＣ－１０４０、成分濃度７５ｗｔ％、マツモトファインケミカル社製）
（ヒドラジン又はヒドラジド化合物）
水加ヒドラジン（日本カーバイド工業社製）
（ストロンチウム化合物）
酢酸ストロンチウム０．５水和物（富士フイルム和光純薬社製）
ギ酸ストロンチウム２水和物
（溶媒）
エチレングリコール
プロピレングリコール
精製水（イオン交換水）
（ｐＨ調整剤）
水酸化カリウム
（アミノシラン化合物）
３－アミノプロピルトリエトキシシラン（東京化成工業社製） The materials used in the examples and comparative examples are as follows.
(Organic titanium acid ester)
Titanium Lactate (Organic TC-310, component concentration 44 wt%, manufactured by Matsumoto Fine Chemical Co., Ltd.)
Phosphoric acid ester titanium complex (Organic acid TC-1040, component concentration 75 wt%, manufactured by Matsumoto Fine Chemical Co., Ltd.)
(Hydrazine or hydrazide compound)
Mizuka Hydrazine (manufactured by Nippon Carbide Industry Co., Ltd.)
(Strontium compound)
Strontium acetate 0.5 hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Strontium formate dihydrate (solvent)
Ethylene glycol Propylene glycol purified water (ion-exchanged water)
(PH regulator)
Potassium hydroxide (aminosilane compound)
3-Aminopropyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.)
（実施例１）
チタンラクテート（オルガチックス　ＴＣ－３１０、成分濃度４４ｗｔ％、マツモトファインケミカル社製）０．５８４ｇに、精製水３．０ｇ及び水加ヒドラジン（日本カーバイド工業社製）３．０ｇを加えて黄色透明溶液とした。
次いで、水酸化カリウム０．４８ｇ、エチレングリコール０．４３２ｇ、精製水５．０８８ｇで調製した溶液を、上記黄色透明溶液に加えて白濁溶液を得た。
その後、得られた白濁溶液に酢酸ストロンチウム０．５水和物（富士フイルム和光純薬社製）０．４２９ｇを加えて、室温条件で３０分攪拌し、透明溶液を得た。得られた透明溶液液を圧力反応容器に入れて２３０℃、１時間の条件で反応させた。なお、圧力は２．８ＭＰａ程度であった。
反応物を含む溶液に対して遠心分離処理（機種名ＳＩＧＭＡ　３－３０ＫＳ、条件１５０００ｒｐｍ、５分）を行い、微粒子を沈降させることで未反応物との分離精製を行った。微粒子を精製水で再分散溶液を作製し、遠心分離処理して微粒子を沈降させる操作を３回繰り返すことで分離精製を完了した。
得られた微粒子を回収し、Ｘ線回折装置（リガク社製、「ＭｉｎｉＦｌｅｘ６００－Ｃ」）にて、観察したところ、チタン酸ストロンチウムの微粒子であることを確認した。 (Example 1)
Add 3.0 g of purified water and 3.0 g of hydrated hydrazine (manufactured by Nippon Carbide Industries) to 0.584 g of titanium lactate (organic TC-310, component concentration 44 wt%, manufactured by Matsumoto Fine Chemical Co., Ltd.) to make a yellow transparent solution. bottom.
Then, a solution prepared with 0.48 g of potassium hydroxide, 0.432 g of ethylene glycol, and 5.088 g of purified water was added to the above yellow transparent solution to obtain a cloudy solution.
Then, 0.429 g of strontium acetate 0.5 hydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cloudy solution, and the mixture was stirred at room temperature for 30 minutes to obtain a transparent solution. The obtained transparent solution was placed in a pressure reaction vessel and reacted at 230 ° C. for 1 hour. The pressure was about 2.8 MPa.
Centrifugal separation treatment (model name SIGMA 3-30KS, condition 15000 rpm, 5 minutes) was performed on the solution containing the reaction product, and the fine particles were settled to separate and purify the unreacted product. Separation and purification was completed by repeating the operation of preparing a redispersion solution of the fine particles with purified water, centrifuging and precipitating the fine particles three times.
The obtained fine particles were collected and observed with an X-ray diffractometer (“MiniFlex600-C” manufactured by Rigaku Co., Ltd.). As a result, it was confirmed that the fine particles were strontium titanate.
（実施例２～８、比較例１～６）
各種材料の配合量、及び、反応条件を表１に記載のように変更したこと以外は、実施例と同様にして、チタン酸ストロンチウム微粒子を製造した。
なお、実施例５及び６では、ｐＨ調整剤（水酸化カリウム）とともに、３－アミノプロピルトリエトキシシランを添加した。
得られた微粒子を回収し、Ｘ線回折装置（リガク社製、「ＭｉｎｉＦｌｅｘ６００－Ｃ」）にて、観察したところ、実施例２～８、及び、比較例４では、チタン酸ストロンチウムの微粒子であることを確認した。
一方、比較例１～３、５及び６では、反応が進行せずチタン酸ストロンチウム微粒子が得られなかった。 (Examples 2 to 8, Comparative Examples 1 to 6)
Strontium titanate fine particles were produced in the same manner as in Examples except that the blending amounts of various materials and the reaction conditions were changed as shown in Table 1.
In Examples 5 and 6, 3-aminopropyltriethoxysilane was added together with the pH adjuster (potassium hydroxide).
The obtained fine particles were collected and observed with an X-ray diffractometer (“MiniFlex600-C” manufactured by Rigaku Co., Ltd.). As a result, they were fine particles of strontium titanate in Examples 2 to 8 and Comparative Example 4. It was confirmed.
On the other hand, in Comparative Examples 1 to 3, 5 and 6, the reaction did not proceed and strontium titanate fine particles could not be obtained.
＜評価方法＞
（粒子形状）
実施例及び比較例で得られた微粒子を回収し、透過型電子顕微鏡（日本電子社製「ＪＥＭ－１０１１」）により観察倍率３０万倍にて観察し、粒子形状を確認した。
確認した微粒子の円形度が、０．９００～１．０００であったものを球状と評価した。 <Evaluation method>
(Particle shape)
The fine particles obtained in Examples and Comparative Examples were collected and observed with a transmission electron microscope (“JEM-1011” manufactured by JEOL Ltd.) at an observation magnification of 300,000 times to confirm the particle shape.
The confirmed fine particles having a circularity of 0.900 to 1.000 were evaluated as spherical.
（結晶性）
実施例及び比較例で得られた微粒子を、透過型電子顕微鏡（日本電子社製「ＪＥＭ－１０１１」）及びＸ線回折装置（リガク社製、「ＭｉｎｉＦｌｅｘ６００－Ｃ」）にて観察し、以下の基準で評価した。
〇：Ｘ線回折装置で算出される結晶子径と透過型電子顕微鏡で観察した粒子径の比率が０．９～１．０
△：Ｘ線回折装置で算出される結晶子径と透過型電子顕微鏡で観察した粒子径の比率が０．９を下回る
×：結晶が生成していない (crystalline)
The fine particles obtained in Examples and Comparative Examples were observed with a transmission electron microscope (“JEM-1011” manufactured by JEOL Ltd.) and an X-ray diffractometer (“MiniFlex600-C” manufactured by Rigaku Ltd.), and the following were observed. Evaluated by criteria.
〇: The ratio of the crystallite diameter calculated by the X-ray diffractometer to the particle diameter observed by the transmission electron microscope is 0.9 to 1.0.
Δ: The ratio of the crystallite diameter calculated by the X-ray diffractometer to the particle diameter observed by the transmission electron microscope is less than 0.9 ×: No crystals are formed.
（平均粒子径）
実施例及び比較例で得られた微粒子５０ｍｇを、５０ｍＬのメタノールに溶解させて分散液を得た。
得られた分散液を測定セルに入れ、レーザ回折・散乱型粒度分布測定機（日機装株式会社製、「マイクロトラックＭＴ３３００ＥＸＩＩ」）にて平均粒子径（Ｄ５０）を測定した。 (Average particle size)
50 mg of the fine particles obtained in Examples and Comparative Examples were dissolved in 50 mL of methanol to obtain a dispersion.
The obtained dispersion was placed in a measuring cell, and the average particle size (D50) was measured with a laser diffraction / scattering type particle size distribution measuring machine (“Microtrack MT3300EXII” manufactured by Nikkiso Co., Ltd.).
（分散性）
実施例及び比較例で得られた微粒子５０ｍｇを、５０ｍＬのメタノールに溶解させて分散液を得た。
得られた分散液をスクリュー管瓶に入れ、背面に黒紙を設置して、分散液の状態を目視にて確認し、以下の基準で評価した。
〇：得られた分散液が透明な溶液であった。
×：得られた分散液が白濁した溶液であった。 (Dispersity)
50 mg of the fine particles obtained in Examples and Comparative Examples were dissolved in 50 mL of methanol to obtain a dispersion.
The obtained dispersion was placed in a screw tube bottle, black paper was placed on the back surface, and the state of the dispersion was visually confirmed and evaluated according to the following criteria.
〇: The obtained dispersion was a transparent solution.
X: The obtained dispersion was a cloudy solution.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
実施例により得られたチタン酸ストロンチウム微粒子は、粒子形状が球形であり、平均粒子径が１４ｎｍ～３０ｎｍであり、結晶性及び分散性に優れていることが確認された。
特に、３－アミノプロピルトリエトキシシランを添加した実施例５及び６では、平均粒子径が小さく、分散性に優れるチタン酸ストロンチウム微粒子を得ることができた。
なお、リン酸エステルチタン錯体を用いた実施例７、溶媒としてプロピレングリコールを用いた実施例８では、分散液の透明性が他の実施例と比較してわずかに低く、他の実施例よりは分散性がわずかに低い結果であった。
一方で、比較例１～３、５及び６では、反応が進行せずチタン酸ストロンチウム微粒子が得られなかった。
また、ヒドラジン又はヒドラジド化合物を含まない、或いは、添加量が所定の範囲ではなかった比較例１～３により得られた微粒子は、平均粒子径が大きく、分散性に劣っていた（分散液が白濁していた）。
また、反応温度が所定の範囲ではなかった比較例４により得られたチタン酸ストロンチウム微粒子は、結晶性が不十分であった。
また、反応時間が長すぎた比較例５により得られた微粒子は、平均粒子径が大きく、分散性に劣っていた（分散液が白濁していた）。
また、反応時間が長く、ｐＨが低かった比較例６では、反応が進行せず、微粒子が得られなかった。　 It was confirmed that the strontium titanate fine particles obtained in the examples had a spherical particle shape and an average particle diameter of 14 nm to 30 nm, and were excellent in crystallinity and dispersibility.
In particular, in Examples 5 and 6 to which 3-aminopropyltriethoxysilane was added, strontium titanate fine particles having a small average particle size and excellent dispersibility could be obtained.
In Example 7 using the phosphoric acid ester titanium complex and Example 8 using propylene glycol as the solvent, the transparency of the dispersion was slightly lower than that of the other examples, and was higher than that of the other examples. The result was that the dispersibility was slightly low.
On the other hand, in Comparative Examples 1 to 3, 5 and 6, the reaction did not proceed and strontium titanate fine particles could not be obtained.
Further, the fine particles obtained in Comparative Examples 1 to 3 which did not contain hydrazine or a hydrazide compound or whose addition amount was not in the predetermined range had a large average particle size and were inferior in dispersibility (the dispersion liquid became cloudy). Was).
Further, the strontium titanate fine particles obtained in Comparative Example 4 in which the reaction temperature was not in the predetermined range had insufficient crystallinity.
Further, the fine particles obtained in Comparative Example 5 in which the reaction time was too long had a large average particle size and were inferior in dispersibility (the dispersion liquid was cloudy).
Further, in Comparative Example 6 in which the reaction time was long and the pH was low, the reaction did not proceed and fine particles could not be obtained.
本発明のチタン酸ストロンチウム微粒子の製造方法は、例えば、高屈折率化剤、熱電変換材料、光触媒、イオン伝導性材料、強誘電材料、磁性材料、触媒材料、酸素電極材料、圧電材料、焦電材料、非線形光学材料、充填剤等の機能性材料として用いることができるチタン酸ストロンチウム微粒子を得ることができる点において有用である。
 

  The method for producing strontium titanate fine particles of the present invention is, for example, a high refractive index agent, a thermoelectric conversion material, a photocatalyst, an ionic conductive material, a dielectric material, a magnetic material, a catalyst material, an oxygen electrode material, a piezoelectric material, and a pyroelectricity. It is useful in that it is possible to obtain strontium titanate fine particles that can be used as functional materials such as materials, nonlinear optical materials, and fillers.

Claims (8)

  1. ヒドラジン又はヒドラジド化合物の存在下、ｐＨが１２以上、反応温度が１５０℃以上２５０℃以下、反応時間が０．５時間以上２時間以下の条件で、
    有機チタン酸エステルと、ストロンチウム化合物とを反応させる反応工程を有し、
    前記有機チタン酸エステルに対する前記ヒドラジン又はヒドラジド化合物のモル比（ヒドラジン又はヒドラジド化合物／有機チタン酸エステル）が１０～７５である
    チタン酸ストロンチウム微粒子の製造方法。     In the presence of hydrazine or hydrazide compound, the conditions are such that the pH is 12 or more, the reaction temperature is 150 ° C or more and 250 ° C or less, and the reaction time is 0.5 hours or more and 2 hours or less.
    It has a reaction step of reacting an organic titanium acid ester with a strontium compound, and has a reaction step.
    A method for producing strontium titanate fine particles, wherein the molar ratio of the hydrazine or the hydrazide compound to the organic titanium acid ester (hydrazine or hydrazide compound / organic titanium acid ester) is 10 to 75.
  2. 有機チタン酸エステルと、ヒドラジン又はヒドラジド化合物とを溶媒中で混合し、混合液を得る混合工程、前記混合液のｐＨを１２以上に調整する調整工程、及び、前記反応工程を有する請求項１に記載のチタン酸ストロンチウム微粒子の製造方法。 The first aspect of the present invention has a mixing step of mixing an organic titanium acid ester and a hydrazine or a hydrazide compound in a solvent to obtain a mixed solution, an adjusting step of adjusting the pH of the mixed solution to 12 or more, and the reaction step. The method for producing strontium titanate fine particles according to the above method.
  3. 前記反応工程を、多価アルコールの存在下で行う請求項１又は２に記載のチタン酸ストロンチウム微粒子の製造方法。 The method for producing strontium titanate fine particles according to claim 1 or 2, wherein the reaction step is performed in the presence of a polyhydric alcohol.
  4. 前記多価アルコールは、エチレングリコールである請求項３に記載のチタン酸ストロンチウム微粒子の製造方法。 The method for producing strontium titanate fine particles according to claim 3, wherein the polyhydric alcohol is ethylene glycol.
  5. 前記有機チタン酸エステルは、チタンラクテートである請求項１～４の何れか一項に記載のチタン酸ストロンチウム微粒子の製造方法。 The method for producing strontium titanate fine particles according to any one of claims 1 to 4, wherein the organic titanic acid ester is titanium lactate.
  6. 前記ストロンチウム化合物は、酢酸ストロンチウム、ギ酸ストロンチウムから選択される少なくとも一種である請求項１～５の何れか一項に記載のチタン酸ストロンチウム微粒子の製造方法。 The method for producing strontium titanate fine particles according to any one of claims 1 to 5, wherein the strontium compound is at least one selected from strontium acetate and strontium formate.
  7. 前記反応工程をアミノシラン化合物の存在下で行う請求項１～６の何れか一項に記載のチタン酸ストロンチウム微粒子の製造方法。 The method for producing strontium titanate fine particles according to any one of claims 1 to 6, wherein the reaction step is carried out in the presence of an aminosilane compound.
  8. 前記アミノシラン化合物は、３－アミノプロピルトリエトキシシランである請求項７に記載のチタン酸ストロンチウム微粒子の製造方法。 The method for producing strontium titanate fine particles according to claim 7, wherein the aminosilane compound is 3-aminopropyltriethoxysilane.
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