Strontium titanate fine particle powder, method for producing the same, dispersion, and resin composition

Abstract

The present invention pertains to a spherical strontium titanate fine-particle powder characterized in that primary particles thereof have an average primary particle size of 50 nm or less, and the ratio of the average primary particle size and a BET-converted particle size derived from a BET specific surface area by using a relational formula: 6000 / (BET×5.13) is in the range of 0.85-1.25.

Description

[Technical Field]

[0001] The present invention aims to obtain strontium titanate fine particle powder, which is optimal as a filler. [Background technology]

[0002] In recent years, with the miniaturization, performance improvement, and weight reduction of various electronic devices, there has been a growing need for organic-inorganic hybrid materials that maintain the processability of organic resins while incorporating the functionality of inorganic fillers (refractive index, dielectric constant, conductivity, magnetism, thermal conductivity, etc.).

[0003] For example, brightness-enhancing films used in displays and diffractive optical elements used in AR / MR glasses require high refractive indices that cannot be achieved with resin alone in order to obtain characteristics such as high brightness, thin film thickness, and improved viewing angle. Therefore, adding inorganic fillers with high refractive indices to the resin to improve the refractive index of the resin film is being investigated.

[0004] Furthermore, with the miniaturization, thinning, and enhancement of electronic components, there is active development underway to replace insulating films, such as those in thin-film transistors (TFTs), from inorganic materials like silicon nitride to resin compositions of resins that are easy to pattern and high-dielectric inorganic fillers.

[0005] The properties required of inorganic fillers in such hybrid materials include increased packing density, uniform dispersion, and suppression of resin film degradation due to hybridization. To satisfy these properties, fine, spherical particles with a good particle size distribution are optimal for increasing packing density, while particles with few particle defects are optimal for uniform dispersion and suppression of resin film degradation.

[0006] On the other hand, strontium titanate is a high-performance material with a perovskite structure and is used in various applications on its own. For example, it is used in pigments that take advantage of its high refractive index, as well as in optical applications such as reflective and light-collecting materials, in ceramic capacitors due to its high dielectric constant, and in visible light photocatalysts due to its photocatalytic activity. Furthermore, it is used in semiconductors, semiconductor capacitors, thermoelectric materials, electroluminescent (EL) materials, and light-emitting materials by taking advantage of its ability to be made semiconductor by adding other elements.

[0007] By forming a composite of strontium titanate, which possesses such high functionality, and resin, it is expected that new materials with functionalities that cannot be achieved with resin alone can be created.

[0008] There have been various reports on strontium titanate nanoparticles in the past (Patent Documents 1-9, Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 6-48734 [Patent Document 2] Japanese Patent Application Publication No. 5-58633 [Patent Document 3] Japanese Patent Publication No. 2003-277054 [Patent Document 4] Japanese Patent Publication No. 2015-137208 [Patent Document 5] Japanese Patent Publication No. 2018-20919 [Patent Document 6] Japanese Patent Publication No. 2019-151507 [Patent Document 7] Japanese Patent Publication No. 2016-69211 [Patent Document 8] Japanese Patent Publication No. 2015-151304 [Patent Document 9] International Publication No. 2015 / 152237 [Non-patent literature]

[0010] [Non-Patent Document 1] Ceramics International (2015), 41, 13516-13524 [Overview of the project] [Problems that the invention aims to solve]

[0011] However, strontium titanate fine particle powder suitable for the aforementioned fillers is currently in high demand, but has not yet been obtained.

[0012] In other words, the aforementioned Patent Document 1 describes a method for producing strontium titanate fine particle powder with an average particle size of 0.05 μm or less, but it does not take into account particle defects in the resulting strontium titanate. Furthermore, this method requires an in-line mixer to mix the reaction instantaneously and uniformly, making the process complex and not industrially desirable.

[0013] Furthermore, the aforementioned Patent Document 2 describes a method for producing strontium titanate by wet-reacting a hydrolysate of a titanium compound with a strontium compound in the presence of hydrogen peroxide. However, strontium titanate also has a large average particle size of 0.1 μm or more, and this method is uneconomical due to the large amount of hydrogen peroxide used.

[0014] Furthermore, while the aforementioned Patent Documents 3 and 4 describe a method of obtaining fine particles of strontium titanate by reacting the hydrolysis product of a titanium compound with a water-soluble strontium salt in a strongly alkaline aqueous solution, these particles are unsuitable as fillers because their shape is rectangular or cubic. In addition, particle defects are not considered, and the ratio of the primary particle size to the BET-equivalent particle size described in the examples suggests that there are many particle defects.

[0015] In addition, in the aforementioned Patent Documents 5 and 6, it is described that a spherical strontium titanate is obtained by reacting a hydrolysis product of a titanium compound and a water-soluble strontium salt in a strongly alkaline aqueous solution with the addition of a hydroxycarboxylic acid or a third component. However, the properties of strontium titanate may change due to the addition of a hydroxycarboxylic acid or other elements, and it is not suitable as a filler for imparting the properties of pure strontium titanate. Also, particle defects are not considered, and it is considered that there are many particle defects from the ratio of the primary particle diameter and the BET-equivalent particle diameter described in the examples.

[0016] In addition, in the aforementioned Patent Documents 7 and 8, cubic strontium titanate with excellent photocatalytic properties is described. However, the shape is controlled to be cubic in order to exhibit the catalytic function, and it is not suitable for use as a resin filler.

[0017] In addition, in the aforementioned Patent Document 9, spherical strontium titanate with an average particle diameter of 50 to 150 nm is described by a wet reaction. However, since the average particle diameter is as large as 50 nm or more and the adhesion to the resin cannot be obtained, it is difficult to say that it is suitable as a filler. Also, particle defects are not considered, and it is considered that there are many particle defects from the ratio of the primary particle diameter and the BET-equivalent particle diameter described in the examples.

[0018] In addition, in the aforementioned Non-Patent Document 1, cubic strontium titanate with a primary particle diameter of 32 to 45 nm is reported. However, since the particle shape is cubic and the packing rate cannot be increased, it is not suitable as a filler.

[0019] Therefore, an object of the present invention is to produce strontium titanate fine particles suitable as a filler in a composite material.

Means for Solving the Problems

[0020] The above object can be achieved by the present invention as follows.

[0021] In other words, the present invention is a spherical strontium titanate fine particle powder characterized in that the average primary particle diameter of the primary particles is 50 nm or less, and the ratio of the average primary particle diameter to the BET equivalent particle diameter derived from the BET specific surface area value using the relational expression: 6000 / (BET × 5.13) is in the range of 0.85 to 1.25 (Invention 1).

[0022] The spherical strontium titanate fine particle powder according to the present invention has reduced particle defects, and when compounded with a resin, the elution of Sr can be suppressed.

[0023] Furthermore, the present invention relates to the strontium titanate fine particle powder described in Invention 1, wherein the spherical strontium titanate fine particle powder has a circularity of 0.8 or higher (Invention 2).

[0024] This method improves the filling properties.

[0025] Furthermore, the present invention is a dispersion containing strontium titanate fine particle powder as described in Invention 1 or 2 (Invention 3).

[0026] Because strontium titanate nanoparticles are suitable as fillers, they can be processed and developed for various applications.

[0027] Furthermore, the present invention is a resin composition comprising strontium titanate fine particle powder and a resin as described in Invention 1 or 2 (Invention 4).

[0028] The aforementioned resin composition can form a functional resin composition. [Effects of the Invention]

[0029] The strontium titanate fine particle powder according to the present invention is fine and has few particle defects, so it can suppress the elution of Sr. Therefore, it can prevent film degradation in composites using this strontium titanate fine particle powder and is suitable as a filler for organic-inorganic hybrid materials. [Modes for carrying out the invention]

[0030] The configuration of the present invention is described in detail as follows:

[0031] The strontium titanate fine particle powder according to the present invention is a spherical particle in which the average primary particle diameter of the primary particles is 50 nm or less, and the ratio of the average primary particle diameter to the BET-converted particle diameter calculated by the following relational formula is in the range of 0.85 to 1.25. Relational formula: 6000 / (BET × 5.13).

[0032] The average primary particle diameter of the primary particles in the strontium titanate fine particle powder according to the present invention is 50 nm or less. By controlling the average primary particle diameter within the above range, a strontium titanate fine particle powder that can be uniformly dispersed in a resin film can be obtained. A preferred average primary particle diameter is 45 nm or less, and more preferably 40 nm or less. The lower limit is approximately 8 nm.

[0033] The ratio of the average primary particle diameter to the BET-equivalent particle diameter (average primary particle diameter / BET-equivalent particle diameter) of the strontium titanate fine particle powder according to the present invention is 0.85 to 1.25. By controlling this ratio within the above range, it is possible to obtain strontium titanate fine particle powder with fewer particle defects and a narrow particle size distribution. If this value is less than 0.85, the BET specific surface area is low relative to the average particle diameter, resulting in many coarse particles and a poor distribution. If the value of the ratio is greater than 1.25, the BET specific surface area is high relative to the average particle diameter, resulting in many defects in the particles. The preferred range is 0.88 to 1.23, and more preferably 0.90 to 1.20.

[0034] The BET specific surface area of ​​the strontium titanate fine particle powder according to the present invention is 23.4 m². 2 A BET specific surface area of ​​23.4 m² is preferable. 2 If the value is less than / g, the average particle size of the strontium titanate fine particle powder will be greater than 50 nm. A more preferable BET specific surface area is 30.0 m². 2 It is 1 / g or more, and more preferably 35m 2It is 120m² or more. The upper limit of the BET specific surface area is 120m². 2 It is approximately / g

[0035] The BET-equivalent particle size of the strontium titanate fine particle powder according to the present invention is preferably 58.8 nm or less, and more preferably 50.0 nm or less. The BET-equivalent particle size is evaluated by the method described later.

[0036] The strontium titanate fine particle powder according to the present invention has a spherical particle shape, and its circularity is preferably 0.8 or higher. If the circularity of the strontium titanate fine particles is less than 0.8, the shape may be rectangular or similar, which may reduce the packing density. A more preferable circularity is 0.82 or higher, and even more preferably 0.83 to 1.0. The circularity is evaluated by the method described later.

[0037] The Sr / Ti ratio of the strontium titanate fine particle powder according to the present invention is preferably 0.90 to 1.10. By controlling the Sr / Ti ratio within this range, the various properties of strontium titanate can be exhibited. A more preferred Sr / Ti ratio is 0.95 to 1.05, and even more preferably 0.98 to 1.02.

[0038] The Sr elution concentration of the strontium titanate fine particle powder according to the present invention is preferably 500 ppm or less. If the Sr elution concentration exceeds 500 ppm, the degradation of the resin film is accelerated by the eluted Sr when creating the composite film. A more preferable Sr elution concentration is 400 ppm or less, and even more preferably 100 to 350 ppm.

[0039] Next, we will describe the method for producing strontium titanate fine particle powder according to the present invention.

[0040] The strontium titanate fine particle powder according to the present invention can be obtained by neutralizing an aqueous titanium tetrachloride solution with an aqueous strontium hydroxide solution to obtain a hydrated titanium hydroxide slurry (neutralization reaction), heating the slurry, washing it with water, adding it to the aqueous strontium hydroxide solution, and carrying out a wet reaction at a temperature range of 60 to 200°C.

[0041] The preferred ratio (Sr / Ti) of titanium raw material to alkaline aqueous solution during the neutralization reaction is 1.1 to 1.8. If the ratio is less than 1.1, the yield of strontium titanate nucleus particles decreases, and if it exceeds 1.8, the distribution of primary strontium titanate particles deteriorates. A more preferred ratio is 1.25 to 1.65.

[0042] After the neutralization reaction, the resulting water-washed titanium hydroxide colloid preferably has a CM of 10 mS / cm or less, and more preferably 8 mS / cm or less.

[0043] The reaction solution for producing strontium titanate nanoparticles preferably has a pH of 11 to 13.5 and a temperature range of 60 to 300°C.

[0044] The reaction concentration of the reaction solution for producing strontium titanate nanoparticles is preferably 0.05 to 0.7 mol / L in terms of titanium compound. If the concentration is less than 0.05 mol / L, the yield is low and not industrially viable, and if it is 0.7 mol / L or higher, the amount of strontium hydroxide in the reaction solution exceeds the solubility, causing Sr(OH)2 to precipitate and making it difficult to carry out a uniform liquid-phase reaction.

[0045] After the neutralization reaction, an aqueous solution of strontium hydroxide is added. The amount of strontium hydroxide solution added should be such that the Sr / Ti ratio is 1.5 to 3.0 relative to the Ti in the reaction solution.

[0046] During the reaction, it is preferable to control the flow of nitrogen to prevent the strontium compound from reacting with carbon dioxide or other gases in the air.

[0047] The reaction temperature for the wet reaction is preferably 60 to 300°C. Below 60°C, it becomes difficult to obtain dense spherical strontium titanate nanoparticles. Above 300°C, designing the hydrothermal vessel becomes difficult. Preferably, the temperature is 65 to 250°C.

[0048] The particles after the wet reaction are washed with water and dried according to conventional methods. Washing with water removes excess strontium. It also removes impurities such as Na, K, and Cl.

[0049] In this invention, a desired strontium titanate fine particle powder can be obtained by controlling the reaction concentration, the Sr / Ti ratio during neutralization, and the Sr / Ti ratio during the wet reaction.

[0050] Furthermore, in this invention, crushing and pulverization processes may be performed.

[0051] In this invention, a dispersion containing strontium titanate can be used.

[0052] The dispersion medium according to the present invention can be either aqueous or solvent-based.

[0053] As dispersion media for aqueous dispersions, water or alcohol-based solvents such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, and butyl alcohol; glycol ether-based solvents such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, and butyl cellosolve; oxyethylene or oxypropylene addition polymers such as diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; alkylene glycols such as ethylene glycol, propylene glycol, and 1,2,6-hexanetriol; and water-soluble organic solvents such as glycerin and 2-pyrrolidone can be used. These dispersion media for aqueous dispersions can be used individually or in combination of two or more depending on the intended application.

[0054] Suitable dispersion media for solvent-based dispersions include aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone and cyclohexanone; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; ether alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; acetic acid esters such as ethyl acetate, butyl acetate, and isobutyl acetate; lactic acid esters such as methyl lactate, ethyl lactate, and propyl lactate; cyclic esters such as ethylene carbonate, propylene carbonate, and γ-butyrolactone; and various monomers. These dispersion media for solvent-based dispersions can be used individually or in combination of two or more depending on the intended application.

[0055] The concentration of strontium titanate fine particle powder in the dispersion according to the present invention is preferably adjusted to 5 to 60% by weight. If it is less than 5% by weight, the productivity for use in the next process will be low, and if it exceeds 60% by weight, it is difficult to say that a highly fluid slurry will be produced. More preferably it is 10 to 55% by weight, and even more preferably 15 to 50% by weight.

[0056] The dispersion according to the present invention may also contain dispersants, additives (resins, defoamers, auxiliary agents, etc.) as needed. The dispersant in the present invention can be appropriately selected and used depending on the type of strontium titanate fine particle powder and dispersion medium used. Examples of dispersants that can be used include organosilicon compounds such as alkoxysilanes, silane coupling agents and organopolysiloxanes, organotitanium compounds such as titanate coupling agents, organoaluminum compounds such as aluminate coupling agents, organozirconium compounds such as zirconate coupling agents, surfactants, or polymer dispersants. These can be used individually or in combination of two or more.

[0057] Examples of the above organosilicon compounds include alkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, tetraethoxysilane, and tetramethoxysilane; silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacroyloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-chloropropyltrimethoxysilane; and organopolysiloxanes such as polysiloxanes, methylhydrogenpolysiloxanes, and modified polysiloxanes.

[0058] The above organic titanium compounds include isopropyltriisostearoyl titanate, isopropyltris(dioctyl pyrophosphate) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, isopropyltri(N-aminoethyl / aminoethyl) titanate, tris(dioctyl pyrophosphate)ethylene titanate, isopropyldioctyl pyrophosphate titanate, isopropyltris(dodecylbenzenesulfonyl) titanate, titanium tetran-normal butoxide, and titanium tetra-2-ethylhexoxy Examples include tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl) phosphite titanate, tetraoctyl bis(ditridecyl phosphate) titanate, tetra(2-2-diallyloxymethyl-1-butyl)bis(ditridecyl) phosphate titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, and bis(dioctyl pyrophosphate) ethylene titanate.

[0059] Examples of the above-mentioned organoaluminum compounds include acetalkoxyaluminum diisopropylate, aluminum diisopropoxymonoethylacetoacetate, aluminum trisethylacetoacetate, and aluminum trisacetylacetonate.

[0060] Examples of the above-mentioned organozirconium compounds include zirconium tetrakisacetylacetonate, zirconium dibutoxybisacetylacetonate, zirconium tetrakisethylacetoacetate, zirconium tributoxymonoethylacetoacetate, and zirconium tributoxyacetylacetonate.

[0061] Examples of the above-mentioned surfactants include anionic surfactants such as fatty acid salts, sulfate esters, sulfonates, and phosphate esters; nonionic surfactants such as polyethylene glycol-type nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene aryl ethers, and polyhydric alcohol-type nonionic surfactants such as sorbitan fatty acid esters; cationic surfactants such as amine salt-type cationic surfactants and quaternary ammonium salt-type cationic surfactants; and amphoteric surfactants such as alkyl betaines such as alkyldimethylaminoacetic acid betaine and alkylimidazolines.

[0062] As polymer dispersants, styrene-acrylic acid copolymers, styrene-maleic acid copolymers, polycarboxylic acids, and their salts can be used.

[0063] The amount of dispersant added depends on the total surface area of ​​the strontium titanate fine particle powder in the dispersion, and can be adjusted appropriately depending on the application of the dispersion and the type of dispersant. Generally, however, by adding 0.01 to 100% by weight of the dispersant to the strontium titanate fine particle powder in the dispersion medium, the strontium titanate fine particle powder can be uniformly and finely dispersed in the dispersion medium, and dispersion stability can also be improved. In addition to directly adding the dispersant to the dispersion medium, the strontium titanate fine particle powder may also be pre-treated with the dispersant.

[0064] The present invention relates to a resin composition containing strontium titanate fine particles in the resin.

[0065] There are no particular restrictions on the resin used, but acrylic resin, polycarbonate, polystyrene resin, polyester resin, polyimide resin, polymethyl methacrylate (PMMA), AS resin, silicone resin, fluororesin, etc. can be used. [Examples]

[0066] A typical embodiment of the present invention is as follows:

[0067] For photographs (25k) of strontium titanate fine particle powder observed using a transmission electron microscope (JEOL Ltd. JEM-F200), the average primary particle diameter was measured from approximately 300 particles. Here, the average primary particle diameter is the particle diameter obtained by averaging the diameter of a circle with an area equivalent to the area determined from the photograph for each particle over all measured particles. The particle shape was determined from the aforementioned electron microscope photographs. Furthermore, the circularity was calculated as (4π × area) / perimeter of the particle measured from the electron microscope photographs. 2 As shown.

[0068] The specific surface area value is the value measured by the BET method (m 2 The values ​​were expressed as ( / g). The BET equivalent particle size (nm) was calculated using the following formula: 6000 / (BET specific surface area × 5.13). Note that 5.13 is the density of strontium titanate (g / cm³). 3 )

[0069] The ratio (average primary particle diameter / BET equivalent particle diameter) is calculated from the average primary particle diameter and the BET equivalent particle diameter.

[0070] The stability of the composite membrane is evaluated by the Sr elution concentration. The Sr elution concentration was determined by adding 2.5 g of strontium titanate nanoparticles to 50 ml of pure water, boiling for 10 minutes, cooling to room temperature, filtering, and measuring the amount of Sr in the filtrate.

[0071] Sr / Ti was measured using an X-ray fluorescence analyzer (Rigaku ZSX PrimusII).

[0072] Example 1 An aqueous titanium tetrachloride solution was mixed with water to a solution with a Ti molar concentration of 2.10 mol / l, and a 20 wt% aqueous strontium hydroxide solution was added so that the Sr / Ti molar ratio was 1.37 to obtain a titanium hydroxide slurry. The slurry was washed with water so that its CM was 10 mS / cm or less. The obtained titanium hydroxide slurry was put into an aqueous strontium hydroxide solution previously dissolved in a reaction vessel. The aqueous strontium hydroxide solution at this time was adjusted so that the Sr / Ti molar ratio was 1.8. Also, the concentration during the reaction was 0.22 mol / l as the strontium titanate concentration. Then, stirring was continued at 180 °C for 8 hours to carry out a hydrothermal reaction. After the reaction, it was cooled to room temperature, and then washed with water with a Nutsche until the electrical conductivity of the filtrate was 200 μS / cm or less, followed by filtration and drying to obtain a white powder of strontium titanate fine particles.

[0073] When the obtained strontium titanate fine particle powder was observed with an electron microscope, it was spherical particles with a primary average particle diameter of 22.7 nm and a circularity of 0.84, and the BET specific surface area was 54.1 m 2 / g, and the ratio of the primary particle diameter to the BET converted particle diameter was 1.05.

[0074] [[ID=IO]]Examples 2 to 6 Strontium titanate fine particle powder was obtained in the same manner as in Example 1 except that the reaction concentration, the amount of strontium hydroxide during neutralization and crystallization, the reaction temperature, and the time were changed.

[0075] The production conditions at this time are shown in Table 1, and the powder properties of the obtained strontium titanate are shown in Table 2.

[0076] Comparative Example 1 The preparation was based on Example 19 of Patent Document 1. Specifically, an aqueous titanium tetrachloride solution was added to pure water and stirred for 1 hour. 5% ammonia water was added dropwise to this solution to obtain a white slurry with a pH of 7.8. After filtering and washing this slurry, it was re-slurried, heated to 60°C, acetic acid was added, and it was aged at pH 6.0 for 40 minutes. After aging, it was filtered and washed to obtain a hydrated titanium hydroxide gel cake. Pure water was added to this hydrated titanium hydroxide gel cake, and then the boiled slurry and strontium hydroxide aqueous solution were adjusted to an Sr / Ti ratio of 1.2. After mixing through an in-line mixer, it was aged under reflux at 80°C for 4 hours. After aging, the slurry was filtered, washed, and dried.

[0077] [Table 1]

[0078] [Table 2]

[0079] The Sr elution concentration in the examples is low, at 500 ppm or less. Therefore, even when the strontium titanate nanoparticles in the examples are used as a filler in the mixing with resin, a stable composite can be produced without degrading the film. This is because the ratio of the primary particle size to the BET-equivalent particle size correlates with the Sr elution concentration, meaning that strontium titanate nanoparticles with few defects are obtained in the examples. [Industrial applicability]

[0080] The strontium titanate fine particle powder of the present invention has the advantage of allowing control over the average particle size depending on the purpose, and being fine, having few defects, and being spherical, which prevents film degradation and makes it easy to increase the filler packing density. Therefore, the strontium titanate fine particle powder of the present invention is ideal as a high refractive index inorganic filler for resin compositions used in brightness-enhancing films used in displays and diffractive optical elements used in AR / MR glasses, or as a high dielectric inorganic filler for high dielectric resin compositions that can be used in electronic components such as thin-film transistors (TFTs).

Claims

1. Spherical strontium titanate fine particle powder characterized by having an average primary particle diameter of 50 nm or less, a BET specific surface area of ​​23.4 m² / g or more, and a ratio of the average primary particle diameter to the BET equivalent particle diameter derived from the BET specific surface area using the relational formula: 6000 / (BET × 5.13) in the range of 0.85 to 1.

25.

2. Strontium titanate fine particle powder according to claim 1, wherein the roundness of the strontium titanate fine particle powder is 0.80 or greater.

3. A dispersion comprising strontium titanate fine particle powder according to claim 1 or 2.

4. A resin composition comprising strontium titanate fine particle powder and a resin according to claim 1 or 2.

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