WO2022070785A1 - Strontium titanate microparticles - Google Patents

Strontium titanate microparticles Download PDF

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Publication number
WO2022070785A1
WO2022070785A1 PCT/JP2021/032618 JP2021032618W WO2022070785A1 WO 2022070785 A1 WO2022070785 A1 WO 2022070785A1 JP 2021032618 W JP2021032618 W JP 2021032618W WO 2022070785 A1 WO2022070785 A1 WO 2022070785A1
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Prior art keywords
fine particles
strontium titanate
titanate fine
strontium
particle size
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PCT/JP2021/032618
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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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Priority claimed from JP2021028961A external-priority patent/JP2022058093A/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 CN202180056602.7A priority Critical patent/CN116057006A/en
Priority to KR1020237004328A priority patent/KR20230075394A/en
Publication of WO2022070785A1 publication Critical patent/WO2022070785A1/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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y35/00—Methods or apparatus for measurement or analysis of nanostructures
    • 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 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. Further, when used as such a functional material, it is necessary to have crystallinity to obtain crystals with high purity.
  • An object of the present invention is to provide strontium titanate fine particles having a small average particle size and excellent crystallinity and dispersibility.
  • the present inventors have diligently studied strontium titanate fine particles, and found that they are produced by containing a specific amount of hydrazine or a hydrazide compound and reacting the organic titanium acid ester with the strontium compound under predetermined conditions (temperature and reaction time). It has been found that the strontium titanate fine particles obtained have a small average particle size and can be excellent in dispersibility.
  • the present invention is strontium titanate fine particles which are spherical and have an average particle diameter (D50) of 10 nm to 30 nm measured by a laser diffraction / scattering type particle size distribution measuring machine.
  • the strontium titanate fine particles of the present invention do not become cloudy when 50 mg of strontium titanate is dissolved in 50 mL of methanol.
  • the ratio of the crystallite diameter calculated by the X-ray diffractometer to the particle diameter observed by the transmission electron microscope is preferably 0.9 to 1.0.
  • the strontium titanate fine particles of the present invention 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.
  • the strontium titanate fine particles of the present invention contain an aminosilane compound, and the content of the aminosilane compound is preferably 0.003 to 0.025 in terms of molar ratio with respect to the hydrazine or hydrazide compound.
  • the strontium titanate fine particles of the present invention preferably have a circularity of 0.900 to 1.000.
  • strontium titanate fine particles having a small average particle size and excellent crystallinity and dispersibility.
  • strontium titanate fine particles are spherical and have an average particle diameter (D50) of 10 nm to 30 nm measured by a laser diffraction / scattering type particle size distribution measuring machine.
  • the strontium titanate fine particles of the present invention have a small average particle size (D50) and are excellent in crystallinity and dispersibility.
  • the strontium titanate fine particles of the present invention 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 of the present invention have an average particle diameter of 10 nm to 30 nm.
  • the average particle size is 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 of the present invention 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 of the present invention 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 of the present invention preferably contain hydrazine or a hydrazide compound in an amount of 0.1% by mass to 60% by mass, preferably 1% by mass to 30% by mass, based on the above-mentioned strontium titanate fine particles. Is more preferable. With such a content, the dispersibility becomes good.
  • the strontium titanate fine particles of the present invention contain an aminosilane compound, and the content of the hydrazine or hydrazide compound is 0.003 to 0. In a molar ratio (aminosilane compound / hydrazine or hydrazide compound) to the strontium titanate fine particles. It is preferably 025. By including the aminosilane compound in the above range, the average particle size of the strontium titanate fine particles can be suitably controlled.
  • the content of the aminosilane compound is more preferably 0.004 to 0.019, and even more preferably 0.007 to 0.015, in terms of molar ratio with respect to the hydrazine or hydrazide compound.
  • the strontium titanate fine particles of the present invention can be produced, for example, by the following method.
  • the organic titanium 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 in the presence of hydrazine or a hydrazide compound. It has a reaction step, and 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.
  • 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 molar ratio (hydrazine or hydrazide compound / organic titanium acid ester) to the organic titanium acid ester is preferably 10 to 75, preferably 30 to 65. Within the above range, the shape of the obtained strontium titanate fine particles can be suitably 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.
  • 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.
  • solvent Water is preferably used as the solvent used in the method for producing the strontium titanate fine particles. 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 above method for producing strontium titanate fine particles, 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 more preferably 12.5 or higher, further preferably 13 or higher, and particularly preferably 13.5 or higher.
  • the content of the pH adjuster is not limited and may be appropriately added according to the target pH.
  • 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.
  • an organic titanium acid ester and a hydrazine or a hydrazide compound are mixed in a solvent to obtain a mixed solution, and a mixing step of adjusting the pH of the mixed solution to 12 or more. , And it is preferable to have 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 titanium 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. Is preferable.
  • the reaction temperature is preferably 150 ° C. or higher and 250 ° C. or lower. If the reaction temperature is less than 150 ° C., the reaction may not proceed and the desired strontium titanate fine particles may not be obtained. If the reaction temperature exceeds 250 ° C., the reaction efficiency is lowered and the obtained strontium titanate particles are obtained. May increase and the dispersibility may decrease.
  • the reaction temperature is preferably 180 to 250 ° C, more preferably 200 to 240 ° C.
  • the reaction time is preferably 0.5 hours or more and 2 hours or less. If the reaction time is less than 0.5 hours, the reaction may not proceed and the desired strontium titanate fine particles may not be obtained. If the reaction time exceeds 2 hours, the reaction efficiency is lowered and the obtained titanium is obtained. The strontium acid acid particles may become large and the dispersibility may decrease.
  • 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.
  • Example 1 To 0.584 g of titanium lactate (Organix TC-310, component concentration 44 wt%, manufactured by Matsumoto Fine Chemical Co., Ltd.), 3 g of purified water and 3.0 g of hydrated hydrazine (manufactured by Nippon Carbide Industries Co., Ltd.) were added to prepare a yellow transparent solution. 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.
  • 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 could not be obtained.
  • 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 strontium titanate fine particles of the present invention are, for example, high refractive index agent, thermoelectric conversion material, photocatalyst, ion conductive material, strong dielectric material, magnetic material, catalyst material, oxygen electrode material, piezoelectric material, pyroelectric material, nonlinearity. It is useful in that it can be used as a functional material such as an optical material and a filler.

Abstract

Provided are strontium titanate microparticles having a small average particle size and excellent crystallinity and dispersibility. Strontium titanate microparticles that are spherical and have an average particle size (D50) measured by a laser diffraction/scattering particle size distribution measurement instrument of 10-30 nm.

Description

チタン酸ストロンチウム微粒子Strontium titanate fine particles
本発明は、チタン酸ストロンチウム微粒子に関する。 The present invention relates to 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。
また、このような機能性材料として用いる場合には、純度が高い結晶が得られる結晶性を有することが必要である。 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.
Further, when used as such a functional material, it is necessary to have crystallinity to obtain crystals with high purity.
国際公開第２０１１／００４７５０号International Publication No. 2011/004750
本発明は、平均粒子径が小さく、結晶性及び分散性に優れるチタン酸ストロンチウム微粒子を提供することを目的とする。 An object of the present invention is to provide strontium titanate fine particles having a small average particle size and excellent crystallinity and dispersibility.
本発明者らは、チタン酸ストロンチウム微粒子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製造したチタン酸ストロンチウム微粒子が、平均粒子径が小さく、分散性に優れることができることを見出した。 The present inventors have diligently studied strontium titanate fine particles, and found that they are produced by containing a specific amount of hydrazine or a hydrazide compound and reacting the organic titanium acid ester with the strontium compound under predetermined conditions (temperature and reaction time). It has been found that the strontium titanate fine particles obtained have a small average particle size and can be excellent in dispersibility.
本発明は、球形であり、レーザ回折・散乱型粒度分布測定機により測定した平均粒子径（Ｄ５０）が１０ｎｍ～３０ｎｍであるチタン酸ストロンチウム微粒子である。
本発明のチタン酸ストロンチウム微粒子は、メタノール５０ｍＬに、上記チタン酸ストロンチウム５０ｍｇを溶解させたときに、白濁が生じない。
また、本発明のチタン酸ストロンチウム微粒子は、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（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であることが好ましい。
また、本発明の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。
また、本発明のチタン酸ストロンチウム微粒子は、アミノシラン化合物を含み、上記アミノシラン化合物の含有量が、上記ヒドラジン又はヒドラジド化合物に対してモル比で０．００３～０．０２５であることが好ましい。
また、本発明のチタン酸ストロンチウム微粒子は、円形度が０．９００～１．０００であることが好ましい。 The present invention is strontium titanate fine particles which are spherical and have an average particle diameter (D50) of 10 nm to 30 nm measured by a laser diffraction / scattering type particle size distribution measuring machine.
The strontium titanate fine particles of the present invention do not become cloudy when 50 mg of strontium titanate is dissolved in 50 mL of methanol.
Further, in the strontium titanate fine particles of the present invention, the ratio of the crystallite diameter calculated by the X-ray diffractometer to the particle diameter observed by the transmission electron microscope (particle diameter observed by the transmission electron microscope / X-ray diffractometer). The calculated crystallite diameter) is preferably 0.9 to 1.0.
Further, the strontium titanate fine particles of the present invention 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.
Further, the strontium titanate fine particles of the present invention contain an aminosilane compound, and the content of the aminosilane compound is preferably 0.003 to 0.025 in terms of molar ratio with respect to the hydrazine or hydrazide compound.
Further, the strontium titanate fine particles of the present invention preferably have a circularity of 0.900 to 1.000.
平均粒子径が小さく、結晶性及び分散性に優れるチタン酸ストロンチウム微粒子を提供することができる。 It is possible to provide strontium titanate fine particles having a small average particle size and excellent crystallinity and dispersibility.
（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は、球形であり、レーザ回折・散乱型粒度分布測定機により測定した平均粒子径（Ｄ５０）が１０ｎｍ～３０ｎｍである。
本発明のチタン酸ストロンチウム微粒子は、平均粒子径（Ｄ５０）が小さく、結晶性及び分散性に優れる。 (Strontium titanate fine particles)
The strontium titanate fine particles of the present invention are spherical and have an average particle diameter (D50) of 10 nm to 30 nm measured by a laser diffraction / scattering type particle size distribution measuring machine.
The strontium titanate fine particles of the present invention have a small average particle size (D50) and are excellent in crystallinity and dispersibility.
本発明の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。
なお、円形度は、透過型電子顕微鏡で撮影した画像の粒子の面積を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。
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 of the present invention 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, the circularity of the strontium titanate fine particles is 0.900 to 1.000.
The circularity can be calculated by circularity = 4πS / L 2 , where S is the area of particles in the image taken with a transmission electron microscope and L is the peripheral length.
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.
本発明の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。
上記平均粒子径は、１４ｎｍ～２５ｎｍであることが好ましい。
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 of the present invention have an average particle diameter of 10 nm to 30 nm.
The average particle size is 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).
本発明の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 of the present invention 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.
本発明の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 of the present invention 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. ..
本発明の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く、１質量％～３０質量％であることがより好ましい。
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 of the present invention preferably contain hydrazine or a hydrazide compound in an amount of 0.1% by mass to 60% by mass, preferably 1% by mass to 30% by mass, based on the above-mentioned strontium titanate fine particles. Is more preferable.
With such a content, the dispersibility becomes good.
本発明のチタン酸ストロンチウム微粒子は、アミノシラン化合物を含み、上記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い。
上記アミノシラン化合物を上記範囲で含むことにより、チタン酸ストロンチウム微粒子の平均粒子径を好適に制御することができる。 The strontium titanate fine particles of the present invention contain an aminosilane compound, and the content of the hydrazine or hydrazide compound is 0.003 to 0. In a molar ratio (aminosilane compound / hydrazine or hydrazide compound) to the strontium titanate fine particles. It is preferably 025.
By including the aminosilane compound in the above range, the average particle size of the strontium titanate fine particles can be suitably controlled.
上記アミノシラン化合物の含有量は、上記ヒドラジン又はヒドラジド化合物に対してモル比で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 more preferably 0.004 to 0.019, and even more preferably 0.007 to 0.015, in terms of molar ratio with respect to the hydrazine or hydrazide compound.
（チタン酸ストロンチウム微粒子の製造方法）
本発明のチタン酸ストロンチウム微粒子は、例えば、以下の方法により製造することができる。
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とする。 (Manufacturing method of strontium titanate fine particles)
The strontium titanate fine particles of the present invention can be produced, for example, by the following method.
The organic titanium 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 in the presence of hydrazine or a hydrazide compound. It has a reaction step, and 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.
（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好適に制御することができる。 As for the content of the hydrazine or the hydrazide compound, the molar ratio (hydrazine or hydrazide compound / organic titanium acid ester) to the organic titanium acid ester is preferably 10 to 75, preferably 30 to 65.
Within the above range, the shape of the obtained strontium titanate fine particles can be suitably 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.
（アミノシラン化合物）
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。 (Aminosilane compound)
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.
（溶媒）
上記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、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)
Water is preferably used as the solvent used in the method for producing the strontium titanate fine particles.
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）
上記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 above method for producing strontium titanate fine particles, 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以上にすることが好ましい。
ｐＨは１２．５以上であることがより好ましく、１３以上であることが更に好ましく、１３．５以上であることが特に好ましい。
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, it is preferable to set the pH 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 more preferably 12.5 or higher, further preferably 13 or higher, and particularly preferably 13.5 or higher.
The content of the pH adjuster is not limited and may be appropriately added according to the target pH.
（その他）
上記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、上記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 above method for producing strontium titanate fine particles, 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, when the 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 becomes large. It ends up.
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.
上記チタン酸ストロンチウム微粒子の製造方法では、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。 In the method for producing strontium titanate fine particles, for example, an organic titanium acid ester and a hydrazine or a hydrazide compound are mixed in a solvent to obtain a mixed solution, and a mixing step of adjusting the pH of the mixed solution to 12 or more. , And it is preferable to have 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ことが好ましい。 In the above reaction step, the organic titanium 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. Is preferable.
上記反応温度は、１５０℃以上２５０℃以下であることが好ましい。
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ないことがあり、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粒子が大きくなって分散性が低下することがある。
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 preferably 150 ° C. or higher and 250 ° C. or lower.
If the reaction temperature is less than 150 ° C., the reaction may not proceed and the desired strontium titanate fine particles may not be obtained. If the reaction temperature exceeds 250 ° C., the reaction efficiency is lowered and the obtained strontium titanate particles are obtained. May increase and the dispersibility may decrease.
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時間以下であることが好ましい。
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ないことがあり、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粒子が大きくなって分散性が低下することがある。
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 preferably 0.5 hours or more and 2 hours or less.
If the reaction time is less than 0.5 hours, the reaction may not proceed and the desired strontium titanate fine particles may not be obtained. If the reaction time exceeds 2 hours, the reaction efficiency is lowered and the obtained titanium is obtained. The strontium acid acid particles may become large and the dispersibility may decrease.
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.
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３ｇ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)
To 0.584 g of titanium lactate (Organix TC-310, component concentration 44 wt%, manufactured by Matsumoto Fine Chemical Co., Ltd.), 3 g of purified water and 3.0 g of hydrated hydrazine (manufactured by Nippon Carbide Industries Co., Ltd.) were added to prepare a yellow transparent solution.
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 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チタン酸ストロンチウム微粒子を回収し、透過型電子顕微鏡（日立ハイテクノロジーズ社製「Ｈ－８００」）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 strontium titanate fine particles obtained in Examples and Comparative Examples were recovered and observed with a transmission electron microscope (“H-800” manufactured by Hitachi High-Technologies Corporation) 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。
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 strontium titanate fine particles obtained in Examples and Comparative Examples were dissolved in 50 mL of methanol to obtain a dispersion liquid.
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。
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 strontium titanate fine particles obtained in Examples and Comparative Examples were dissolved in 50 mL of methanol to obtain a dispersion liquid.
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含む実施例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 containing 3-aminopropyltriethoxysilane, 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点において有用である。

  The strontium titanate fine particles of the present invention are, for example, high refractive index agent, thermoelectric conversion material, photocatalyst, ion conductive material, strong dielectric material, magnetic material, catalyst material, oxygen electrode material, piezoelectric material, pyroelectric material, nonlinearity. It is useful in that it can be used as a functional material such as an optical material and a filler.

Claims (6)

  1. 球形であり、レーザ回折・散乱型粒度分布測定機により測定した平均粒子径（Ｄ５０）が１０ｎｍ～３０ｎｍであるチタン酸ストロンチウム微粒子。 Strontium titanate fine particles having a spherical shape and an average particle diameter (D50) of 10 nm to 30 nm measured by a laser diffraction / scattering type particle size distribution measuring machine.
  2. メタノール５０ｍＬに、前記チタン酸ストロンチウム５０ｍｇを溶解させたときに、白濁が生じない請求項１に記載のチタン酸ストロンチウム微粒子。 The strontium titanate fine particles according to claim 1, wherein when 50 mg of strontium titanate is dissolved in 50 mL of methanol, white turbidity does not occur.
  3. 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（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である請求項１又は２に記載のチタン酸ストロンチウム微粒子。 The ratio of the crystallite diameter calculated by the X-ray diffractometer to the particle diameter observed by the transmission electron microscope (particle diameter observed by the transmission electron microscope / crystallite diameter calculated by the X-ray diffractometer) is 0.9. The strontium titanate fine particles according to claim 1 or 2, which is ~ 1.0.
  4. ヒドラジン又はヒドラジド化合物の含有量が、前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％である請求項１～３の何れか一項に記載のチタン酸ストロンチウム微粒子。 The strontium titanate fine particles according to any one of claims 1 to 3, wherein the content of the hydrazine or the hydrazide compound is 0.1% by mass to 60% by mass with respect to the strontium titanate fine particles.
  5. アミノシラン化合物を含み、前記アミノシラン化合物の含有量が、前記ヒドラジン又はヒドラジド化合物に対してモル比で０．００３～０．０２５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。 The strontium titanate fine particles according to any one of claims 1 to 4, which contain an aminosilane compound and whose content of the aminosilane compound is 0.003 to 0.025 in terms of molar ratio with respect to the hydrazine or hydrazide compound. ..
  6. 円形度が、０．９００～１．０００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。 The strontium titanate fine particles according to any one of claims 1 to 5, which have a circularity of 0.900 to 1.000.
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