TW201704188A - Barium titanate particle powder, and dispersion and coating film containing said powder - Google Patents

Abstract

The purpose of the present invention is to provide a barium titanate particle powder having high transparency when made into a film due to fineness thereof, a sharp particle size distribution, and little elution of Ba ion which inhibits dispersion. Barium titanate particle powder having a primary particle average particle diameter of 10-60 nm, a particle coefficient of variation (standard deviation of particle size distribution divided by average particle diameter) of 0.35 or less, and 1,000 ppm or less of Ba ion eluted from the powder into an aqueous solvent, and a dispersion and coating film containing the barium titanate particle powder.

Description

Barium titanate particle powder, dispersion, resin composition

An object of the present invention is to provide a barium titanate particle powder which has a high transparency and a sharp particle size distribution when film formation is fine, and which has a small amount of eluted cerium ions.

Barium titanate having a higher dielectric constant is widely used as a dielectric material for laminated ceramic capacitors and the like.

Further, the optical film used in various displays or the like is controlled by adding an inorganic particle filler such as zirconia to a transparent resin to control the dielectric constant and the refractive index. The TFT for liquid crystal display control is also required to use a material having fine particles and a high dielectric constant as a material for an insulating film due to low power.

For example, the TFT needs to be exposed to etching or the like for patterning. Since there are many cesium ions eluted, when the powder is in contact with an organic component such as a dispersant, a binder, or a resin having an acidic functional group, an undesired reaction may occur, and the organic component may be passivated and may be incapable of being removed. The drawbacks of the coating film having a higher transparency are obtained.

Moreover, in order to use the barium titanate for the aforementioned optical use, the demand The barium titanate particle powder having a large dielectric constant and a refractive index is obtained by refining the particle diameter to ensure transparency and reducing the amount of cerium ion eluted.

When the dielectric thin film is formed, a small particle diameter and an unnecessary impurity are not obtained, and good electrical characteristics are known. Therefore, several prior art techniques for designing barium titanate by synthesis have appeared (Patent Document 1). The cited document 1 describes barium titanate having a narrow particle size distribution, but it is still insufficient for optical use.

Further, the prior art has disclosed a technique for coating the surface of a perovskite compound, but the patent document 2 coated with ceria is intended to be a coating process for dispersing stability, and the effect of preventing cerium oxide from eluting cerium is not described.

In the method of etching or the like, there has been a patent document (Patent Documents 3 and 4) which adds an element which weakens the surface layer of the BaTiO ₃ particle, and it is a method for improving the reactivity with the additive, but the manufacturer cannot introduce the dissolution by the literature. The effect. Further, Patent Document 5 has described that barium titanate exists in a stoichiometric ratio, but there is no description of the application to a weak substance.

Prior technical literature Patent literature

Patent Document 1: JP-A-2005-008445

Patent Document 2: Japanese Patent Publication No. 09-202864

Patent Document 3: JP-A-2011-184247

Patent Document 4: Japanese Laid-Open Patent Publication No. Hei 11-335177

Patent Document 5: International Publication No. 2014/077176

At present, the most demanding material is barium titanate particle powder which meets the aforementioned characteristics, but has not yet appeared.

Therefore, the technical object of the present invention is to provide a barium titanate particle powder which is suitable for film formation and has high transparency, and which is fine and has a small amount of cesium ions eluted and has a sharp particle size distribution.

The above technical problems can be achieved by the present invention described below.

That is, the present invention is a barium titanate particle having an average particle diameter of 10 nm or more and 60 nm or less, a standard deviation of the particle size distribution divided by an average particle diameter of 0.35 or less, and a cerium ion amount in which the powder is dissolved in an aqueous solvent. 1000 ppm or less (Invention 1).

Further, the barium titanate particle powder according to the first aspect of the invention, wherein the particle surface is coated with at least one surface selected from the group consisting of a cerium compound, a titanium compound, a zirconium compound, an aluminum compound, a cerium compound, a sulfur compound, and a phosphoric acid compound. (Invention 2).

Further, the present invention is a barium titanate particle powder, which is a coating amount of the surface coating material according to the _second aspect of the invention, wherein the cerium compound is converted in terms of SiO ₂ , the titanium compound is converted in terms of carbon, and the other elements are converted in terms of each element. It is 0.05 to 5.0% by weight (Invention 3).

Further, the present invention is as described in the first aspect of the present invention The heat is obtained by heat treatment at a temperature ranging from 100 to 500 ° C (Invention 5).

The barium titanate particle powder of the present invention is fine particles, and has a small amount of cerium ions eluted and has a high dielectric constant, and thus is suitable as an optical material.

Fig. 1 is an electron micrograph of a barium titanate particle powder obtained in Example 1.

The constitution of the present invention will be described in detail below.

The primary particle diameter (x) of the primary particles of the barium titanate particle powder of the present invention is 10 to 60 nm. By controlling the average particle diameter of the primary particles to the above range, it is possible to form a barium titanate particle powder excellent in transparency. The average particle diameter of the primary particles is preferably from 10 to 58 nm, more preferably from 10 to 55 nm.

The amount of barium ions dissolved in the aqueous solvent from the barium titanate particle powder of the present invention is 1000 ppm or less. When the amount of cerium ions dissolved in the aqueous solvent exceeds 1000 ppm, the dispersion containing the barium titanate particles hinders the function of the dispersing agent, and as a result, the transparency for the coating film is lowered. It is preferably 900 ppm or less, more preferably 800 ppm or less. When the average particle diameter of the primary particles of the barium titanate particle powder is small, the specific surface area is large, and the tendency is to reduce the crystallization. Sexuality, therefore tends to increase the amount of cesium dissolved. Further, the amount of ruthenium ions in which the barium titanate particle powder is dissolved in the water solvent is calculated by an evaluation method described later.

The coefficient of variation (particle size distribution (σ) divided by the average particle diameter (x) of the primary particles) of the primary particles of the barium titanate particle powder of the present invention is 0.35 or less. The lower limit of the coefficient of variation is generally 0.2. When the above numerical value is controlled within the above range, a barium titanate particle powder excellent in particle size distribution can be formed. It is preferably 0.20 to 0.348, more preferably 0.20 to 0.30.

The surface of the particles of the barium titanate particle powder of the present invention may be coated with at least one surface selected from the group consisting of a cerium compound, a titanium compound, a zirconium compound, an aluminum compound, a cerium compound, a sulfur compound, and a phosphoric acid compound.

Each of the above-mentioned compounds coated on the surface of the particles of the barium titanate particle powder of the present invention can effectively suppress the elution of cerium, and therefore has a function of effectively reducing the elution of cerium ions and improving the dispersibility. Further, it is possible to reduce the elution of the cerium ions by the water washing described later. However, even if the water washing step is not completed, the cerium ion elution can be reduced by coating the surface of the particles.

In the cerium compound, the inorganic compound containing cerium is preferably water glass or other ceric acid salt, and the organic compound containing cerium is methyl triethoxy decane, dimethyl diethoxy decane, phenyl three. Ethoxy decane, diphenyl diethoxy decane, methyl trimethoxy decane, dimethyl dimethoxy decane, phenyl trimethoxy decane, diphenyl dimethoxy decane, ethyl triethyl Oxy decane, propyl triethoxy decane, butyl triethoxy decane, isobutyl trimethoxy decane, hexyl trimethoxy decane, hexyl triethoxy decane, octyl triethoxy decane and hydrazine Alkane such as triethoxy decane Oxaloxane, vinyltrimethoxydecane, vinyltriethoxydecane, γ-aminopropyltriethoxydecane, γ-glycidoxypropyltrimethoxydecane, γ-mercaptopropyl Trimethoxydecane, γ-methacryloxypropyltrimethoxydecane, N-(β-aminoethyl)-γ-aminopropyltrimethoxydecane, γ-glycidoxypropane Methyl dimethoxy decane, p-styryl trimethoxy decane, p-styryl triethoxy decane, p-styryl trichloro decane, p-styryl triphenoxy decane, etc. a decane compound such as a decane coupling agent, a polyoxyalkylene oxide, a methylhydrogenated polyoxyalkylene or an organic polyoxyalkylene such as a modified polyoxyalkylene or a decane monomer. Further, an organic compound and/or an inorganic compound of each element may be used as the compound selected from the group consisting of a titanium compound, a zirconium compound, an aluminum compound, and a cerium compound. The sulfur compound is preferably a sulfate or a phosphoric acid compound, preferably a phosphoric acid. Compound. Further, it is expected that one or more compounds selected from the group consisting of a titanium compound, a zirconium compound, an aluminum compound, a cerium compound, a sulfur compound, and a phosphoric acid compound have an effect of suppressing sintering.

The coating amount of the surface coating is preferably 0.05 to 5.0% by weight in terms of SiO ₂ in terms of SiO ₂ and the amount of the titanium compound in terms of carbon, and the aluminum compound, the cerium compound, the sulfur compound, and the phosphoric acid compound are 0.05 to 5.0% by weight in terms of each element. Preferably, it is 0.1 to 4.5% by weight.

The barium titanate particle powder of the present invention has a permittivity measured by a later-described evaluation method of 300 or more. The upper limit of the permittivity is generally 2000. By controlling the dielectric constant of the barium titanate particle powder to the above range, fine particles which suppress the growth of the particles can be obtained. The permittivity is preferably 350 or more, more preferably 350 to 1500.

The crystallinity of the barium titanate particle powder of the present invention is preferably less than 1.003 when the lattice constant ratio c/a of the a-axis length (a) and the c-axis length (c) of the lattice constant is used. In terms of the particle diameter of the present invention, it is industrially difficult to produce barium titanate particle powder having a lattice constant ratio c/a of 1.003 or more.

The barium titanate particle powder of the present invention preferably has a specific surface area of 20 to 80 m ² /g. When the particle size is less than 20 m ² /g, the particles are coarsened, and the particles are sintered to each other to form particles, so that the binder is easily dispersed and dispersed. It is industrially difficult to produce barium titanate particle powder having a specific surface area value of more than 80 m ² /g. The BET specific surface area is preferably 25 to 80 m ² /g, more preferably 30 to 75 m ² /g.

The Ba/Ti of the barium titanate particle powder of the present invention is preferably from 0.750 to 1.000. When the Ba/Ti ratio is controlled to the above range, a barium titanate particle powder having a higher dielectric property can be obtained. It is preferably 0.770~0.990, more preferably 0.780~0.980.

The particle shape of the barium titanate particle powder of the present invention is preferably spherical or granular. The shape other than the spherical shape may cause the particles to be in contact with each other in a point contact manner to lower the dispersibility and to lower the smoothness of the coating film due to the edge of the particles.

Next, a method for producing the barium titanate particle powder of the present invention will be explained.

The barium titanate particle powder of the present invention is obtained by washing a barium titanate particle powder having an average particle diameter of 10 to 60 nm prepared by hydrothermal reaction in advance to remove the eluted barium component. That is, it is preferred to form titanium by hydrothermal method. Acid bismuth particle powder.

The present invention is not limited to a hydrothermal reaction. For example, after the aqueous solution of cesium hydroxide is dropped into an aqueous solution of titanium chloride to neutralize the colloidal titanium hydroxide, the titanium hydroxide colloid is poured into an aqueous solution of barium hydroxide, and the mixture is heated and mixed. The solution forms barium titanate. After cooling and washing with water, it is hydrothermally treated in a sealed container at a temperature ranging from 65 to 250 ° C, washed with water, dried, and pulverized.

In the hydrothermal reaction, a highly differentiated barium titanate can be produced by changing the reaction temperature, concentration, pH, and the like.

The average particle diameter of barium titanate obtained by hydrothermal reaction is preferably from 10 to 60 nm.

The barium titanate particles (particle diameter: 10 to 60 nm) produced by hydrothermal reaction are washed to a Ba/Ti ratio of 0.750 to 1.000, whereby the barium titanate particle powder of the present invention can be obtained. It is preferably 0.770~0.990, more preferably 0.780~0.980. The acid resistance and dielectric constant of the barium titanate particles can be controlled by controlling the cleaning conditions. The washing condition control is, for example, washing with water until the cerium ions cannot be confirmed (for example, the electrical conductivity of the water-washed filtrate is 100 μS/cm or less), and then washing with warm water to pH=7 or the like.

Further, by uniformly mixing the cerium solution and the titanium solution, more specifically, the input port of the titanium solution into the cerium solution is plural, the variation coefficient of the particles (the standard deviation of the particle size distribution divided by the average particle diameter) can be controlled. 0.35 or less.

Further, the barium titanate particle powder of the present invention is heat-treated at a temperature ranging from 100 to 500 ° C, and can be obtained without loss of particle size distribution and dispersibility. A barium titanate particle powder having a higher dielectric constant.

Next, the dispersion of the present invention will be explained.

Any of the aqueous system and the solvent system can be used as the dispersion medium of the present invention.

The dispersion medium of the aqueous dispersion may be water, or an alcohol solvent such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol or butyl alcohol; methyl cellosolve, ethyl cellosolve, and C. Glycol ester solvent such as cellosolve or butyl cellosolve; acetaldehyde or propionaldehyde addition polymerization of diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, etc. An alkanediol such as ethylene glycol, propylene glycol or 1,2,6-hexanetriol; a water-soluble organic solvent such as glycerin or 2-pyrrolidone. The dispersion medium for the aqueous dispersions may be used singly or in combination of two or more depending on the intended purpose.

As the dispersion medium for the solvent dispersion, an aromatic hydrocarbon such as toluene or xylene; a ketone such as methyl ethyl ketone or cyclohexanone; N,N-dimethylformamide, N,N-di can be used. Amidoxime such as methyl acetamide or N-methylpyrrolidone; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol single Ether ethers such as ethyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, etc. Ether acetates; acetates such as ethyl acetate, butyl acetate, isobutyl acetate; lactate such as methyl lactate, ethyl lactate, propyl lactate; ethylene carbonate, propylene carbonate And cyclic esters such as γ-butyrolactone and various monomers. The dispersion medium for the solvent-based dispersions may be used singly or in combination of two or more depending on the intended purpose.

The dispersing machine for producing the dispersion of the present invention is not particularly limited, and a device capable of applying shearing force, impact force, compressive force and/or frictional force to the powder layer is preferable, and for example, a roll grinder or a high-speed swivel can be used. Grinder, classifier built-in high-speed rotary grinder, ball grinder, media agitator grinder, airflow mill, compaction shear grinder, colloid mill, roller mill, etc.

The dispersion of the present invention contains 0.1 to 60 parts by weight of barium titanate particle powder per 100 parts by weight of the substrate of the dispersion, preferably 0.5 to 50 parts by weight, more preferably 1 to 40 parts by weight. The constituent base material of the dispersion of the barium titanate particle powder is formed of a dispersion medium in addition to the above-described barium titanate particle powder, and a dispersant, an additive (resin, antifoaming agent, auxiliary agent, etc.) or the like may be added as necessary.

The dispersant of the present invention can be appropriately selected depending on the type of the barium titanate particle powder and the dispersion medium to be used, and an alkoxysilane, a decane coupling agent, an organic ruthenium compound such as an organic polysiloxane, or a titanate can be used. An organic titanium compound such as an organic titanium compound such as a coupling agent, an organoaluminum compound such as an aluminate coupling agent, or an organic zirconium compound such as a zirconate coupling agent, a surfactant or a polymer dispersant, etc., which may be used alone or in combination The above is mixed.

The above organic hydrazine compound such as methyltrimethoxydecane, methyltriethoxydecane, dimethyldiethoxydecane, phenyltriethoxydecane, ethyltriethoxydecane, propyltriethyl Alkoxy decane, vinyl trimethoxy, such as oxydecane, butyltriethoxydecane, hexyltriethoxydecane, octyltriethoxydecane, tetraethoxydecane, and tetramethoxydecane矽, vinyl triethoxy decane, γ-aminopropyl triethoxy fluorene Alkane, γ-glycidoxypropyltrimethoxydecane, γ-mercaptopropyltrimethoxydecane, γ-methylpropenyloxypropyltrimethoxydecane, N-(β-aminoethyl a decane coupling agent such as γ-aminopropyltrimethoxydecane, γ-glycidoxypropylmethyldimethoxydecane or γ-chloropropyltrimethoxydecane, or polyoxyalkylene oxide An organic polyoxane such as methyl hydrogenated polyoxyalkylene or modified polyoxyalkylene.

The above organotitanium compound such as isopropyl triisostearyl strontium titanate, isopropyl tris(dioctyl pyrophosphate) titanate, bis(dioctylpyrophosphate)oxyacetate titanate , isopropyl tris(N-aminoethyl ‧ aminoethyl) titanate, tris(dioctyl pyrophosphate) vinyl titanate, isopropyl dioctyl pyrophosphate titanate, different Propyltris(dodecylbenzenesulfonate) titanate, titanium tetra-n-butoxide, titanium tetra-2-ethylhexoxide, tetraisopropylbis(dioctylphosphite) titanate , tetraoctyl bis(ditridecylphosphite) titanate, tetrakis(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanium Acid salt, tetraoctyl bis(ditridecyl phosphate) titanate, tetrakis(2-2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphate titanium An acid salt, bis(dioctylpyrophosphate)oxytitanate acetate, bis(dioctylpyrophosphate)vinyl titanate or the like.

The above organoaluminum compound is, for example, acetoxy aluminum diisopropylate, aluminum diisopropoxy monoethyl acetonitrile acetate, aluminum triethyl acetonitrile acetate, aluminum triethyl decyl pyruvate.

The above organozirconium compound is, for example, zirconium tetraethenyl pyruvate, zirconium dibutoxy bis acetoacetate, zirconium tetraethyl acetonitrile Salt, zirconium tributoxy monoethyl acetoacetate, zirconium tributoxyethyl phthalate, and the like.

The above surfactants are, for example, anionic surfactants such as fatty acid salts, sulfate ester salts, sulfonate salts, and phosphate ester salts; polyethylene oxide alkyl ethers, polyethylene oxide aryl ethers, and the like. Nonionic surfactants such as alcoholic nonionic surfactants, sorbitan fatty acid esters, and the like, and other nonionic surfactants; amine salt type cationic surfactants; quaternary ammonium salt type cationic systems A cationic surfactant such as a surfactant; an amphoteric surfactant such as an alkylbetaine or an alkylimidazoline such as an alkyldimethylaminoacetic acid betaine.

As the polymer dispersant, a styrene-acrylic acid copolymer, a styrene-maleic acid copolymer, a polycarboxylic acid, a salt thereof, or the like can be used.

The amount of the dispersant added depends on the total surface area of the barium titanate particle powder in the dispersion, and can be appropriately adjusted according to the dispersion use of the barium titanate particle powder and the type of the dispersant, but generally relative to the titanic acid in the dispersant. By adding 0.01 to 100% by weight of the dispersant to the cerium particle powder, the barium titanate particle powder can be uniformly and finely dispersed in the dispersion medium, and the dispersion stability can be improved. Further, the above dispersing agent may be previously treated with a barium titanate particle powder in addition to being directly added to the dispersion medium.

Next, the coating film of the present invention will be explained.

When the coating film (or sheet) of the present invention is produced, a resin is added to the dispersion, and after mixing, it is formed on a film of a PET film or the like using a coater such as a bar coater or a spin coater.

The resin used is generally acrylic resin, polyoxymethylene resin, epoxy Resin, polyester resin, polyimide resin, polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC), and the like.

The total light transmittance of the coating film or sheet of the present invention is preferably 85% or more, more preferably 88% or more, and the haze is 2% or less, preferably 1% or less.

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In the present invention, a barium titanate particle powder having a very fine particle shape, a small amount of eluted cerium ions, and a high dielectric constant and high heat resistance can be obtained. The particles used for the film requiring transparency are required to have a sharp particle size distribution in addition to the fine particles, and the barium titanate particle powder of the present invention can satisfy the conditions. The prior barium titanate particles obtained by the solid phase method or the oxalate method or the like are pulverized into an ultrafine shape, but they are not suitable for this use because of their wide particle size distribution.

The hydrothermal method which is advantageous for synthesizing fine particles is one in which a particle which is defective in the design is produced at the beginning, and one of the methods for removing an unnecessary compound at the time of washing is sufficiently obtained, whereby desired characteristics can be obtained.

Further, in the present invention, the surface treatment of cerium oxide or the like can further reduce the elution amount of cerium ions. Further, even if the temperature is not calcined, it is possible to obtain a barium titanate particle having a good refractive index and a dielectric constant by further reducing the elution amount of the cerium ions.

Representative embodiments of the present invention are as follows.

The average particle diameter (x) of the primary particles of the barium titanate particle powder is a photograph observed by a scanning electron microscope (Hitachi, S-4300) (magnification: 50,000 times), and about 500 particles are measured. The particle size is obtained, and the particle size distribution (σ) is obtained at the same time. The coefficient of variation is a value obtained by dividing the particle size distribution (σ) by the average particle diameter (x) of the primary particles (the particle size distribution (σ/x) in Table 1 indicates a coefficient of variation).

The barium titanate particle powder was evaluated by powder X-ray diffraction, and the c/a ratio of the lattice number and the half value width (FWHM) of the (111) plane were measured.

The specific surface area value indicates the value measured by the BET method.

The Ba/Ti composition ratio was measured using a "fluorescence X-ray analyzer Simultix12" (manufactured by Likaku Co., Ltd.).

The cesium dissolution concentration was obtained by dispersing 5 g of barium titanate particle powder in 100 cc of pure water, boiling for 7 minutes, cooling to room temperature, and filtering, followed by measurement using an ICP emission spectroscopic analyzer (Seiko Electronics SPS400). The value of 20 degrees of the obtained cerium concentration is used as the amount of cerium ions dissolved in the water solvent from the powder, that is, the amount of cerium eluted.

The surface coating content of the barium titanate particle powder is quantified by a measurement method in accordance with the type of the surface coating element. In other words, the ruthenium compound is a fluorescent X-ray measurement device (Lijia Library SMX6), and the phosphoric acid compound, the aluminum compound, and the ruthenium compound are used in an ICP emission spectrometer (Seiko Electronics SPS400), and the sulfur compound is used in a carbon-sulfur analysis. The device (Mitsubishi EMIA-920) measures the content of each coating element. Further, since the titanium compound cannot be distinguished from the titanium amount of the barium titanate particle powder itself, the amount of carbon before and after the surface coating of the barium titanate particle powder is measured using a carbon-sulfur analyzer (EMIA-920), and then borrowed. The amount of surface coating was quantified from the difference in the amount of carbon (the amount of carbon after surface treatment - the amount of carbon before surface treatment).

The permittivity of the barium titanate particle powder was measured by the following evaluation method.

Specifically, 2.5 g of a barium titanate particle powder and 0.5 g of a polyvinyl alcohol (PVA) aqueous solution having a concentration of 3 wt% were mixed, and then pressed at a pressure of 100 kg/cm ^{2 to} prepare a disk-shaped pressure of 25 mm in diameter and 1 to 2 mm in thickness. Powder. Since the pressed powder contains moisture, it is placed in dry air at 50 ° C for 12 hours or more. After drying, the volume ratio of barium titanate particle powder, PVA and voids was determined from the weight and volume of the compact. Further, the green compact is adjusted so that the barium titanate particle powder is 41 to 55 vol%, the PVA is 0.1 to 3 vol%, and the residual portion is void.

The dielectric constant of the obtained green compact was measured at 10 MHz in an environment of about 25 ° C and a humidity of about 40% RH by an impedance analyzer E4991A and a dielectric constant measuring device 16453A manufactured by Agilent. The obtained dielectric constant measurement result is provided by each component derived from barium titanate particle powder, PVA, and voids. Therefore, the measured value from the logarithmic mixing in the present invention is estimated to be only imparted by barium titanate. Further, the dielectric constant of the barium titanate particles coated on the surface is calculated by logarithmic mixing to estimate the dielectric constant for the composite particles containing the surface-treated component.

[Example 1]

1.12 kg of ytterbium hydroxide octahydrate (97% Ba(OH) ₂ ‧8H ₂ O reagent grade made by Kanto Chemical Co., Ltd.) was dissolved in water, and the purified product was dropped into 688 g of an aqueous solution of titanium chloride, and neutralized. Hydrogen oxyhydroxide colloid. Next, 1.28 kg of barium hydroxide octahydrate was dissolved in water, and the product was purified in a hydrothermal reaction vessel under a nitrogen atmosphere at a temperature of 70 ° C and a pH of 12.5. Next, the titanium hydroxide colloid was placed in the aqueous solution of cesium hydroxide in 2 minutes. The mixed solution was subjected to a hydrothermal reaction at 100 ° C for 0.75 hours to form barium titanate. After cooling to room temperature, the mixture was washed with a nucleus funnel until the filtrate was free of hydrazine ions, and then washed with warm water to pH = 7. Thereafter, it was filtered, and dried at 150 ° C to obtain a barium titanate particle powder. The obtained barium titanate particle powder had a Ba/Ti ratio of 0.874 molar ratio and an average particle diameter of 33 nm. An electron micrograph of the obtained barium titanate particle powder is shown in Fig. 1.

[Embodiment 2]

The reaction time of the hydrothermal reaction was changed to 8 hours with respect to Example 1, and the mixture was washed to pH = 6.5 to obtain a barium titanate particle powder having an average particle diameter of 52 nm having a Ba/Ti ratio of 0.962 mol ratio. When the load of the hydrothermal reaction condition is increased, the average particle diameter can be increased to obtain a barium titanate particle powder having a relatively high Ba/Ti composition. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Example 3]

The reaction temperature of the hydrothermal reaction was changed to 70 ° C with respect to Example 1, and the mixture was washed to pH = 6.5 to obtain a barium titanate particle powder having an average particle diameter of 16 nm. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Example 4]

After degumming the barium titanate particle powder obtained in Example 1 with a small amount of water, 1% by weight of sodium citrate No. 3 was added with respect to barium titanate while stirring. The solution (water glass No. 3) was adjusted to pH 6.5 with acetic acid, and washed with a nucleus funnel to confirm that the filtrate had no cerium ions, and then filtered and dried to obtain a barium titanate particle powder having a Ba/Ti ratio of 0.790 mol ratio. The obtained barium titanate particle powder was evaluated in the same manner as in Example 1. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Example 5]

While stirring the barium titanate particle powder obtained in Example 1 with a mixer, a 5 wt% alkyl decane decane coupling agent (trade name: TSL-8241) was added to obtain a surface-treated barium titanate particle powder. The properties of the barium titanate particle powder are shown in Table 1.

[Embodiment 6]

The barium titanate particle powder of Example 1 was heat-treated at a temperature of 300 °C. The dielectric constant, c/a ratio, half-value width, cerium elution amount, and specific surface area of the obtained barium titanate particle powder were evaluated in the same manner as in the first embodiment. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Embodiment 7]

The barium titanate particle powder of Example 2 was heat-treated at a temperature of 500 °C. The dielectric constant, c/a ratio, half-value width, cerium elution amount, and specific surface area of the obtained barium titanate particle powder were evaluated in the same manner as in the first embodiment. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Embodiment 8]

After heat treating the barium titanate particle powder of Example 1 at a temperature of 500 ° C, the obtained treated barium titanate particle powder was degummed to a concentration of 15% by weight in pure water, and then washed with a nube funnel until the filtrate was confirmed. After purifying the ions, wash them with warm water until pH=7. Thereafter, it was filtered and dried to obtain a barium titanate particle powder. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Embodiment 9]

1.12 kg of ytterbium hydroxide octahydrate (97% Ba(OH) ₂ ‧8H ₂ O reagent grade made by Kanto Chemical Co., Ltd.) was dissolved in water, and the purified product was dropped into 688 g of an aqueous solution of titanium chloride. After neutralization, hydrogen was obtained. Titanium oxide colloid. Next, 1.28 kg of barium hydroxide octahydrate was dissolved in water, and the purified product was stored in a hydrothermal reaction vessel at a temperature of 70 ° C and a pH of 12.5 in a nitrogen atmosphere. Next, the titanium hydroxide colloid was placed in the aqueous solution of cesium hydroxide in 2 minutes. The mixed solution was subjected to a hydrothermal reaction at 100 ° C for 0.75 hours to form barium titanate. After cooling to room temperature, it was washed with a nucleus funnel to a filtrate of 900 μS/cm, and then slowly added with aluminum sulfate in an amount of 1% by weight in terms of aluminum. Thereafter, it was filtered and dried to obtain a barium titanate particle powder coated with an aluminum compound. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Embodiment 10]

The barium titanate particle powder coated with the cerium compound was obtained by the same method as in Example 9 except that the additive was cerium chloride. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Example 11]

The sulfate-coated barium titanate particle powder was obtained by the same method as in Example 9 except that the additive was sodium sulfate and the amount was 0.1% by weight in terms of sulfur. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Embodiment 12]

A phosphoric acid-coated barium titanate particle powder was obtained in the same manner as in Example 9 except that the additive was phosphoric acid. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Example 13]

The tetrabasic bis(dioctylphosphite) titanate of the organotitanium compound was added while stirring the barium titanate particle powder obtained in Example 1 with a mixer so that the difference in carbon amount before and after the surface treatment was 0.5% by weight. The surface treated barium titanate particle powder. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Embodiment 14]

The tetrabasic bis(dioctylphosphite) titanate of the organotitanium compound was added while stirring the barium titanate particle powder obtained in Example 1 with a mixer so that the difference in carbon amount before and after the surface treatment was 1% by weight. The surface treated barium titanate particle powder. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Comparative Example 1]

The slurry containing barium titanate obtained after the hydrothermal reaction obtained in the step of Example 1 was washed with a small amount of water, and dried to obtain a barium titanate particle powder. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Comparative Example 2]

After heat-treating the barium titanate particle powder having an average particle diameter of 33 nm obtained in Example 1 at a temperature of 700 ° C, the dielectric constant, c/a ratio, half-value width and specific surface area were evaluated in the same manner as in Example 1. Although the permittivity can be greatly increased by heat treatment at a high temperature, the average particle diameter is also greatly increased. Therefore, it is known from Comparative Example 5 described later that the total light transmittance and turbidity of the sheet are deteriorated. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Comparative Example 3]

The dielectric constant, c/a ratio, half-value width, cerium elution amount, and specific surface area of the barium titanate particle powder produced by the solid phase method were evaluated in the same manner as in the first embodiment. The characteristics of the obtained barium titanate particle powder are shown in Table 1.

[Example 15]

A 70 vol% zirconia beads (particle size 50 μm) placed in a stirred vessel in a 0.5 L stirrer made of zirconia in a vertical ball mill ("Utra UAM-05" manufactured by Teppup Industries, Inc.). And a mixed solution of ED153 (manufactured by Nanben Chemical Co., Ltd.) and a solvent PGMEA as a dispersing agent Thereafter, the barium titanate particle powder obtained in Example 1 was cyclically dispersed for 1 hour to obtain a dispersion of barium titanate particle powder.

[Example 16]

The dispersion obtained by mixing barium titanate/binder (containing dispersant) = 6/4 with acrylic resin (SB-193 岐阜 拉 库 )) was applied to Lumir-U by a bar coater. On a film of -46 (made by Toray), a film having a film thickness of about 3 μm was produced.

[Example 17]

The barium titanate particle powder of Example 3 was subjected to flaking according to the methods of Example 15 and Example 16. The characteristics of the obtained sheet are shown in Table 2.

[Embodiment 18]

The barium titanate particle powder of Example 4 was subjected to flaking according to the methods of Example 15 and Example 16. The characteristics of the obtained sheet are shown in Table 2.

[Embodiment 19]

The barium titanate particle powder of Example 6 was subjected to flaking according to the methods of Example 15 and Example 16. The characteristics of the obtained sheet are shown in Table 2.

[Comparative Example 4]

The barium titanate particle powder of Comparative Example 1 was subjected to flaking according to the methods of Example 15 and Example 16. The characteristics of the obtained sheet are shown in Table 2.

[Comparative Example 5]

The barium titanate particle powder of Comparative Example 2 was subjected to flaking according to the methods of Example 15 and Example 16. The characteristics of the obtained sheet are shown in Table 2.

It is understood from Table 2 that the coating film (Examples 16 to 19) using the barium titanate particle powder of the present invention (Examples 16 to 19) has excellent total light transmittance of 85% or more and haze of 1% or less. Transparency.

Industrial use possibility

The barium titanate particle powder of the present invention is suitable for various dielectric materials because it has excellent dispersibility for suppressing aggregation. It is particularly suitable for use in a laminated ceramic capacitor for the purpose of delaying the sintering of the internal electrode layer of nickel, and particularly when the nickel is fine, the barium titanate particle powder of the present invention is highly suitable. Further, since the barium titanate particle powder of the present invention has a high dielectric constant, when the barium titanate particle powder is mixed with a transparent resin, it is inferred that the amount of the barium titanate particle powder can be suppressed before use, and it is easy to ensure the use of the optical film. The necessary transparency.

Claims (8)

A barium titanate particle powder characterized in that the average particle diameter of the primary particles is 10 nm or more and 60 nm or less, and the coefficient of variation of the particles (the standard deviation of the particle size distribution divided by the average particle diameter) is 0.35 or less and is eluted from the powder. The amount of cerium ions in the aqueous solvent is 1000 ppm or less. The barium titanate particle powder of claim 1, wherein the particle surface is coated with a surface coating of at least one selected from the group consisting of a cerium compound, a titanium compound, a zirconium compound, an aluminum compound, a cerium compound, a sulfur compound, and a phosphoric acid compound. A barium titanate particle powder which is a coating amount of the surface coating material of claim 2, wherein the cerium compound is converted to SiO ₂ in terms of carbon, and the other compound is 0.05 to 5.0% by weight in terms of each element. The barium titanate particle powder according to any one of claims 1 to 3, wherein the permittivity is 300 or more. The barium titanate particle powder according to any one of claims 1 to 4, which is obtained by heat-treating at a temperature ranging from 100 to 500 °C. The barium titanate particle powder according to any one of claims 1 to 5, which is obtained by a hydrothermal method. A dispersion comprising the barium titanate particle powder according to any one of claims 1 to 6. A coating film containing the barium titanate particle powder according to any one of claims 1 to 6.