Barium titanate particulate powder and production method therefor

Abstract

[Problem] To provide: a barium titanate particulate powder which is fine and highly crystalline, can be suitably used as a raw material for a small-sized, high-performance electronic component or optical component due to the easy dispersion properties thereof in both an aqueous solvent and a non-aqueous solvent, and can also be suitably used for MLCC due to the low ignition loss thereof; and a production method therefor. [Solution] The barium titanate particulate powder has an average primary particle diameter of 20 nm to 150 nm, wherein a value of D95 / D50 is 5 or less, where D50 is a diameter of aggregated particles in an aqueous solvent corresponding to 50% of the cumulative frequency distribution and D95 is a diameter corresponding to 95% of the cumulative frequency distribution, and the maximum torque of oil absorption characteristics is 0.2 N·m or less.

Description

Barium titanate particle powder and its manufacturing method

[0001] The present invention relates to barium titanate particles and a method for producing the same, and more particularly to barium titanate particles that are highly crystalline and fine, and easily dispersible in both aqueous and non-aqueous solvents, making them suitable for use as a raw material for small, high-performance electronic and optical components, and that have low ignition loss and are therefore suitable for use in MLCCs, and a method for producing the same.

[0002] In recent years, there has been an accelerating trend toward smaller and lighter electronic devices such as mobile phones and personal computers, which has led to the miniaturization and increased capacity of capacitors in the electrical circuits contained in these devices, as well as the miniaturization and increased transmittance of optical films.

[0003] As electronic and optical components become smaller, have higher capacities, and have higher transmittances, there is an increasing demand for barium titanate particle powders that are highly crystalline, fine, and easily dispersible in both aqueous and non-aqueous solvents.

[0004] From the viewpoint of reducing the thickness of resin films containing barium titanate particles used in the above-mentioned parts, there is an increasing demand for barium titanate particles that are easily dispersible in both aqueous and non-aqueous solvents.

[0005] In addition, in a multilayer ceramic capacitor (hereinafter referred to as "MLCC") in which dielectric layers and internal electrode layers are alternately stacked, barium titanate particle powder is used as the raw material for the dielectric layers, and Ni particle powder is used as the raw material for the internal electrode layers.

[0006] In recent years, MLCCs have become smaller and have larger capacities, and the thicknesses of the dielectric layers and internal electrode layers are each 1 μm or less. This means that the particle sizes of the raw materials, barium titanate particle powder and Ni particle powder, are also required to be submicron or smaller.

[0007] MLCC is usually manufactured by preparing a slurry or paste for forming the dielectric layer and the internal electrode layer, and then alternately stacking and firing dry films of the slurry, etc., so that the Ni particles in the internal electrode layer and the barium titanate particles in the dielectric layer are sintered simultaneously.

[0008] However, Ni particles of submicron size or smaller are sintered at temperatures several hundred degrees Celsius lower than barium titanate particles of the same size, and therefore, due to the difference in thermal contraction characteristics between Ni particles and barium titanate particles, there is a problem in that the laminated dielectric layers and internal electrode layers are prone to peeling.

[0009] Highly crystalline and fine barium titanate particle powders that can be easily dispersed in both aqueous and non-aqueous solvents can be suitably used as raw materials for small electronic and optical components. Furthermore, when barium titanate particle powders that have the above properties and low ignition loss are used in MLCCs and sintered, peeling between the dielectric layer and the Ni internal electrode layer is unlikely to occur, and it is expected that MLCCs with high mechanical reliability can be manufactured.

[0010] Takeshi Nomura, editor, "Latest Trends in Materials, Manufacturing, and Mounting Technology for Multilayer Ceramic Capacitors (MLCC)," published by R&D Support Center, Inc., October 30, 2020. Science and Technology Agency, Inorganic Materials Research Institute Research Report No. 19, "Research on Titanium Oxide," 1979.

[0011] Japanese Patent Application Laid-Open No. 2005-289668

[0012] Non-Patent Document 1 and Patent Document 1 describe the use of fine, highly dispersible barium titanate particles as a sintering retarder for Ni particles.

[0013] However, the techniques described in Non-Patent Document 1 and Patent Document 1 require the use of a large amount of dispersant as a co-material to disperse the barium titanate particles among the Ni particles, or the application of a strong mechanical shear to disperse the particles.

[0014] However, if a large amount of dispersant is used or if strong shear is applied, chipping of the barium titanate particles and Ni particles occurs, which may make the material unusable as a raw material for thin-layer ceramic capacitors or small electronic and optical components.

[0015] The present inventors have set solving the above problems as a technical task, and as a result of numerous trial and error trials and experiments, have discovered that the average primary particle diameter is 20 nm or more and 150 nm or less, and the 50% diameter D of the cumulative frequency distribution of aggregated particles in an aqueous solvent is５０ and 95% diameter D ９５ D represented by ９５ / D ５０ The above technical object has been achieved by obtaining the remarkable finding that barium titanate particle powder having a value of 5 or less and a maximum torque of 0.2 N m or less in the oil absorption characteristics is highly crystalline and fine barium titanate particle powder that is easily dispersed in both aqueous and non-aqueous solvents and has a small ignition loss.

[0016] The above technical problems can be solved by the present invention as follows.

[0017] The present invention relates to a method for producing agglomerated particles having an average primary particle diameter of 20 nm or more and 150 nm or less, and a 50% diameter D of a cumulative frequency distribution of agglomerated particles in an aqueous solvent. ５０ and 95% diameter D ９５ D represented by ９５ / D ５０ The barium titanate particle powder has a value of 5 or less and a maximum torque of 0.2 N·m or less in oil absorption characteristics.

[0018] The present invention also relates to the barium titanate particles, wherein the work of a twin-screw kneader in the oil absorption characteristics is 40 J / g or less.

[0019] The present invention also relates to the barium titanate particles having an ignition loss of 4.0 wt % or less.

[0020] The present invention also provides a method for producing barium titanate particle powder, which includes at least a first step of producing a mixed titanate of orthotitanic acid and metatitanic acid by a solution reaction in an aqueous solvent, and a second step of mixing the mixed titanate with a barium compound at 60°C or higher and 105°C or lower to produce barium titanate.

[0021] The present invention also relates to the method for producing barium titanate particle powder, in which the first step is a step of dehydrating orthotitanic acid produced from titanium chloride and a neutralizing agent at a temperature of 50°C or higher and 85°C or lower to produce a mixed titanic acid of orthotitanic acid and metatitanic acid.

[0022] The present invention also provides the method for producing barium titanate particles, wherein the mixed titanate in the first step contains impurity elements in an amount of 1000 ppm or less.

[0023] The present invention also provides a method for producing a mixed titanic acid by using TiO ２ ・nH ２ In the method for producing barium titanate particles, when n is represented by 0.0, the n of the mixed titanate in the first step satisfies 0.5≦n≦1.5.

[0024] The present invention also provides a method for producing a polymer having an average primary particle diameter of 20 nm or more and 150 nm or less, and a 50% diameter D of a cumulative frequency distribution of aggregated particles in an aqueous solvent. ５０ and 95% diameter D ９５ D represented by ９５ / D ５０ The barium titanate particle powder has an oil absorption characteristic of (36-0.08 x average primary particle diameter) mL / 100 g or less at the time of maximum torque.

[0025] The present invention also provides a dispersion containing the barium titanate particles.

[0026] The barium titanate particle powder according to the present invention is a barium titanate particle powder having a fine average primary particle diameter of 20 nm to 150 nm, high crystallinity, easy dispersion in both aqueous and non-aqueous solvents, and low ignition loss.

[0027] Therefore, when the barium titanate particle powder according to the present invention is added as a co-material to a paste containing Ni particles for use in the internal electrode layers of an MLCC, the barium titanate particles can be uniformly dispersed around the Ni particles.

[0028] Since the barium titanate particles are uniformly dispersed, a Ni paste with low viscosity can be produced.

[0029] Furthermore, in the Ni dried film using the above-mentioned Ni paste, barium titanate particles uniformly dispersed around the Ni particles are observed. Therefore, the thermal shrinkage due to sintering of the above-mentioned Ni dried film is reduced by the grain growth suppression effect of the Ni particles. Therefore, the difference in thermal shrinkage characteristics between the Ni internal electrode layer obtained from each paste dried film and the dielectric layer containing barium titanate particle powder is reduced, and even if the Ni internal electrode layer and the dielectric layer are sintered simultaneously, peeling between the Ni internal electrode layer and the dielectric layer is unlikely to occur.

[0030] Furthermore, simultaneous firing increases the mechanical strength, making it possible to provide a highly reliable MLCC.

[0031] Furthermore, a slurry in which the barium titanate particles according to the present invention are dispersed can be made into a resin film having a high dielectric constant and a high refractive index, and can also be used to form a thin film, making it suitable for use in capacitors and optical films.

[0032] 1 is a scanning electron microscope (SEM) image (25,000x magnification) of the barium titanate particle powder of Example 1. 2 is a particle size distribution of primary particles and aggregated particles in an aqueous solvent of the barium titanate particle powder of Example 1. 3 is an oil absorption characteristic of 15 g of the barium titanate particle powder of Example 1. 4 is a graph showing the dependence of oil absorption at maximum torque on the average primary particle size in Examples and Comparative Examples.

[0033] The configuration of the present invention will be described in more detail below.

[0034] First, the barium titanate particles according to the present invention will be described.

[0035] The average primary particle size of the barium titanate particles according to the present invention is 20 nm to 150 nm, preferably 25 nm to 140 nm, and more preferably 30 nm to 130 nm.

[0036] If the particle size is less than 20 nm, it is difficult to industrially, i.e., safely and mass-produce barium titanate particle powder that satisfies the cumulative frequency distribution of agglomerated particles and the maximum torque requirements for oil absorption characteristics in the present invention. On the other hand, if the particle size exceeds 150 nm, there is a risk that the particle size cannot be used for applications such as small electronic components and optical components.

[0037] The barium titanate particle powder according to the present invention has a diameter of 50% of the cumulative frequency distribution of aggregated particles in an aqueous solvent, D ５０ and 95% diameter D ９５ D represented by ９５ / D ５０ The value of D is 5 or less, preferably 1.9 or less, and more preferably 1.8 or less. ９５ / D ５０ If the value exceeds 5, the particles may not be easily dispersed in the aqueous solvent.

[0038] The barium titanate particles according to the present invention have an oil absorption characteristic of a maximum torque of 0.2 N·m or less, preferably 1.9 N·m or less, and more preferably 1.8 N·m or less.

[0039] If the viscosity exceeds 0.2 N·m, the particles may not be easily dispersed in the non-aqueous solvent.

[0040] The barium titanate particles according to the present invention preferably have a twin-screw kneader work in terms of oil absorption characteristics of 40 J / g or less, more preferably 38 J / g or less, and even more preferably 36 J / g or less.

[0041] If the density exceeds 40 J / g, there is a risk that the polymer will not be easily dispersed in a non-aqueous solvent.

[0042] The barium titanate particles according to the present invention preferably have an ignition loss of 4.0 wt % or less, more preferably 3.8 wt % or less, and even more preferably 3.6 wt % or less.

[0043] The main causes of the loss on ignition are thought to be the thermal decomposition of unreacted barium carbonate in the sample and the desorption of water of crystallization and chemically adsorbed water. Therefore, if the loss on ignition exceeds 4.0 wt%, the sample is considered to have poor crystallinity and may not be usable as a raw material for electronic and optical components.

[0044] The barium titanate particles according to the present invention are preferably of high purity, since there is a risk that the barium titanate particles may affect electronic and optical components that use the barium titanate particles.

[0045] Examples of impurity elements that may have an effect include Si, S, Cl, Ca, Fe, and Sr derived from the main raw material, and N, Na, and K derived from the neutralizing agent.

[0046] The impurity elements derived from the main raw materials are each preferably 500 ppm or less, more preferably 400 ppm or less, and even more preferably 300 ppm or less.

[0047] The impurity elements derived from the neutralizing agent are each preferably 20 ppm or less, more preferably 18 ppm or less, and even more preferably 16 ppm or less.

[0048] The barium titanate particles according to the present invention preferably have a Ba / Ti composition ratio of 0.980 to 1.020, more preferably 0.985 to 1.015, and even more preferably 0.990 to 1.010.

[0049] If it is less than 0.980, a large amount of unreacted titanium remains, which may result in low crystallinity and a decrease in the dielectric constant and refractive index, and if it exceeds 1.020, the amount of unreacted barium carbonate increases, which may similarly result in a decrease in the dielectric constant and refractive index.

[0050] The barium titanate particles according to the present invention have a BET specific surface area of ​​6.0 m ２ / g~70m ２ / g, and more preferably 6.2 m ２ / g~65m ２ / g.

[0051] BET specific surface area is 6.0m ２ / g~70m ２ / g, the converted particle size determined by the BET specific surface area and true density is close to the average primary particle size, and the barium titanate particles are highly crystalline.

[0052] The barium titanate particles according to the present invention preferably have a crystallite size of 12 nm to 180 nm, more preferably 15 nm to 170 nm.

[0053] This is because if the crystallite size is 12 nm to 180 nm, each particle is close to being a single crystal.

[0054] The barium titanate particles according to the present invention preferably have an oil absorption of 45 mL / 100 g or less, more preferably 42 mL / 100 g or less, at the time of maximum torque.

[0055] If the oil absorption at the maximum torque exceeds 45 mL / 100 g, the binder may not be easily dispersed in a non-aqueous solvent.

[0056] In the powder according to the present invention, when the barium titanate particles have an average primary particle size of 25 nm or more, the lattice constant ratio c / a is preferably 1.0010 to 1.0250, more preferably 1.0030 to 1.0200.

[0057] If it is less than 1.0010, the dielectric constant and refractive index may decrease due to the low crystallinity of the barium titanate, and it is difficult to produce barium titanate that exceeds 1.0250.

[0058] In the case of barium titanate particles having an average primary particle size of less than 25 nm, the lattice constant ratio c / a approaches 1 due to the particle size effect.

[0059] The barium titanate particles according to the present invention have an oil absorption characteristic of (36-0.08×average primary particle diameter) mL / 100 g or less at the time of maximum torque.

[0060] Next, a method for producing the barium titanate particles according to the present invention will be described.

[0061] The method for producing barium titanate particles according to the present invention will be described using a solution reaction in an aqueous solvent, as it is recognized that a solution reaction in an aqueous solvent is most suitable. However, the method is not limited to the solution reaction, and may be a solid-phase method in which raw materials are mixed, pulverized, and calcined, or a sol-gel method in which metal alkoxide is hydrolyzed.

[0062] Generally, titanium tetrachloride TiCl is used as a raw material for barium titanate particle powder. ４ There is.

[0063] Since Cl in titanium tetrachloride is an impurity element, it is known that titanic acid derived from titanium tetrachloride is washed with water to produce high-purity barium titanate.

[0064] Usually, in a solution reaction using an aqueous solvent, TiCl ４ When titanic acid is produced using the above as a raw material, the following neutralization reaction represented by (Formula A), dehydration reaction represented by (Formula B), and hydrolysis reaction represented by (Formula C) are typical reactions.

[0065] (Neutralization reaction) (Formula A) TiCl ４ +4MOH→Ti(OH) ４ +4MCl <(Formula A) where M is Na, K, NH ４ , etc., where MOH is a neutralizing agent. The neutralizing agent is Ca(OH) ２ The hydroxide of a divalent metal such as M'CO ３ It may also be a carbonate.

[0066] (Dehydration reaction) (Formula B) TiO ２ ・nH ２ O → TiO ２ (n-1)H ２ O+H ２ O < (Formula B), n≦2. Here, TiO ２ ・nH ２ In O, when n = 2, it is orthotitanic acid, when n = 1, it is metatitanic acid, and when 1 < n < 2, it is a mixed titanic acid of orthotitanic acid and metatitanic acid. Orthotitanic acid is Ti(OH) ４ , metatitanic acid TiO(OH) ２ Also, orthotitanic acid is expressed as H ４ TiO ４ , metatitanic acid H ２ TiO ２ Here, orthotitanic acid is an amorphous or low-crystalline titanic acid, and metatitanic acid is treated as an aggregate of crystalline anatase microcrystals. The TiO of the titanic acid produced ２ ・nH ２ O (n≦2) is in the state of a white precipitate or a white dispersion. Therefore, the mixed titanic acid of orthotitanic acid and metatitanic acid is TiO ２ ・nH ２ O (0<n<2).

[0067] (Hydrolysis reaction) (Formula C) TiCl ４ + (m + 2) H ２O → TiO ２ ・mH ２ O + 4HCl <In formula C, m depends on the concentration of titanium tetrachloride in the reaction solution, pH, impurities in the solution, etc., and at relatively high temperatures and pH levels, metatitanic acid with m ≈ 1 is produced.> Here, the hydrolysis reaction of titanium tetrachloride refers to the formation of a white precipitate or white dispersion when water is added to titanium tetrachloride in a transparent solution, or the formation of a white precipitate or white dispersion after a certain period of time has passed when water is added to titanium tetrachloride.

[0068] The first and second steps in the method for producing barium titanate particles according to the present invention will be described.

[0069] The preparation method of the present invention is based on the reaction of (Equation A) and (Equation B).

[0070] The manufacturing method of the present invention is characterized in that the first step is to produce a mixed titanic acid of orthotitanic acid and metatitanic acid, and then the second step is to mix the produced mixed titanic acid with a barium compound at 60°C to 105°C to produce barium titanate by solution reaction.

[0071] The production method of the present invention will be described in more detail below.

[0072] In the manufacturing method of the present invention, titanium tetrachloride TiCl is used as the main raw material titanium chloride. ４ For example, industrial titanium chloride (Cl / Ti<4) can be used.

[0073] In the production method of the present invention, it is preferable to carry out the dehydration reaction of (Equation B) after the neutralization reaction of (Equation A). That is, it is preferable to carry out the neutralization reaction by adding a neutralizing agent dropwise to industrial titanium chloride (Cl / Ti<4) diluted with water at a low temperature, and the low temperature is in the range of 10°C to 60°C, more preferably 20°C to 55°C.

[0074] If the reaction temperature of (formula A) exceeds 60°C during the dropwise addition, heat is generated during the neutralization of titanium chloride, which may cause the hydrolysis reaction of (formula C) to proceed. If the reaction temperature is below 10°C, industrial control is difficult.

[0075] In the production method according to the present invention, the MOH / Cl value (molar ratio), which is the ratio of the neutralizing agent MOH to Cl in titanium chloride, is preferably 0.60 to 1.50, more preferably 0.70 to 1.40, and even more preferably 0.80 to 1.30.

[0076] If the MOH / Cl value exceeds 1.50, titanates containing M are produced, and it is difficult to remove M by washing with water, which may result in a large amount of impurity M remaining in the obtained barium titanate particle powder. If the MOH / Cl value is below 0.60, unreacted titanium chloride remains, and as a result of the titanium chloride being washed away during washing with water, the yield of the obtained barium titanate particle powder may decrease.

[0077] In the method for producing barium titanate particles according to the present invention, the Ti concentration after the neutralization reaction of (Equation A) and during the dehydration reaction of (Equation B) is preferably 0.2 mol / L to 3.5 mol / L, more preferably 0.3 mol / L to 3.2 mol / L, and even more preferably 0.35 mol / L to 3.0 mol / L.

[0078] After the neutralization reaction (formula A), the dehydration reaction (formula B) is preferably carried out at 50°C to 85°C, more preferably 52°C to 83°C.

[0079] If the temperature is less than 50°C, the dehydration reaction is unlikely to occur, whereas if the temperature exceeds 85°C, titanic acid, which has low reactivity with barium, may be produced.

[0080] A part of the orthotitanic acid is converted to metatitanic acid by the dehydration reaction, resulting in a mixed titanic acid containing orthotitanic acid and metatitanic acid.

[0081] The neutralization reaction through the dehydration reaction are preferably carried out in a state where the reaction solution is exposed to an oxidizing gas atmosphere, because in an inert gas atmosphere, impurities are likely to remain in the titanate obtained after the subsequent water washing step, making it difficult to obtain a high-purity barium titanate particle powder.

[0082] The oxidizing atmosphere may be a pure oxygen atmosphere or an air atmosphere, or may be actively exposed to an oxidizing atmosphere by bubbling air into the reaction solution.

[0083] The titanic acid obtained in the first step is preferably a mixed titanic acid of orthotitanic acid obtained by a neutralization reaction (formula A) and metatitanic acid obtained by a dehydration reaction (formula B), and preferably does not contain any hydrolyzate formed by the reaction (formula C) of titanium chloride in a strongly acidic atmosphere.

[0084] On the other hand, metatitanic acid can be produced according to (Equation C) at a pH of 0.5 to 3.5 and a temperature of 40°C to 80°C, and mixed with a mixed titanic acid of orthotitanic acid obtained by the neutralization reaction (Equation A) and metatitanic acid obtained by the dehydration reaction (Equation B) to produce a mixed titanic acid.

[0085] The mixed titanic acid obtained immediately after the first step may be washed with water, because impurity elements contained in the mixed titanic acid obtained in the first step can be washed away by washing with water.

[0086] The end point of the water washing is when the filtrate conductivity reaches 200 μS / cm, and the impurity elements contained in the mixed titanic acid after the water washing can be measured.

[0087] The impurity elements contained in the mixed titanic acid after washing with water are preferably 1000 ppm or less, more preferably 800 ppm or less, and even more preferably 500 ppm or less.

[0088] If the impurity elements exceed 1000 ppm each, there is a risk that any of the impurity elements Si, S, Cl, Ca, Fe, and Sr derived from the main raw material will exceed 500 ppm in the barium titanate particle powder obtained in the second step or later, and there is also a risk that any of the alkali metal elements Na and K, which are impurities derived from the neutralizing agent, will exceed 20 ppm.

[0089] Mixed titanic acid is TiO ２ ・nH ２ When expressed as 0, the mixed titanate in the first step preferably has n=0.5≦n≦1.5, more preferably 0.55 to 1.4. When n exceeds 1.5, washing with water becomes difficult, impurity elements tend to remain, the crystallinity of the obtained barium titanate tends to be low, the particle surface is not smooth, and the oil absorption characteristics tend to deteriorate. Furthermore, when n is less than 0.5, the reactivity with Ba in the second step tends to be low, and a barium titanate with a low reactivity is likely to be obtained.

[0090] It is known that when an alkaline barium solution and titanic acid are mixed, the titanic acid dissolves and barium titanate particles are produced. This model can sometimes explain the impurities in titanic acid and the impurities in the resulting barium titanate.

[0091] In the second step, the mixed titanic acid and the barium compound are reacted in an aqueous solution to produce barium titanate particles.

[0092] In the second step, the slurry containing the mixed titanic acid obtained in the first step is mixed with the barium compound as the main raw material, and the mixture is preferably reacted in an alkaline environment at a temperature in the range of 60°C to 105°C.

[0093] The barium compound is preferably of high purity. The barium compound is not particularly limited, but barium hydroxide is an example.

[0094] The gas that comes into contact with the solution during the reaction is preferably an oxidizing gas that does not contain carbon dioxide or an inert gas such as high-purity nitrogen, in order to prevent the formation of barium carbonate.

[0095] After the second step, the barium titanate particles may be crystallized by hydrothermal treatment.

[0096] The obtained slurry containing barium titanate particles may be washed with water to remove impurities such as excess Ba derived from the main raw material.

[0097] Barium titanate particles produced in an aqueous solution can be converted into barium titanate particle powder by removing the water used in the solution reaction. In this case, it is preferable to prevent strong aggregation of the barium titanate particles by cross-linking water. Examples of methods for preventing aggregation include, for example, instantaneous drying of a slurry containing barium titanate particles or drying by replacing the slurry with a solvent having a lower cross-linking strength than water, according to conventional methods. Furthermore, the barium titanate particle powder dried from the slurry can be dry-pulverized to prevent strong aggregation of the particles.

[0098] The resulting particle powder can be further calcined and pulverized to increase the crystallinity of the barium titanate.

[0099] Next, the dispersion containing the barium titanate particles according to the present invention will be described.

[0100] The dispersion medium according to the present invention may be either aqueous or non-aqueous.

[0101] Examples of the dispersion medium for the aqueous dispersion include water, 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. These dispersion media for aqueous dispersions can be used alone or in combination depending on the intended use.

[0102] Examples of dispersion media for non-aqueous 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; acetate 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 non-aqueous dispersions can be used alone or in combination depending on the intended use.

[0103] The concentration of the barium titanate particles in the dispersion according to the present invention is preferably adjusted to 5 to 60% by weight, more preferably 10 to 55% by weight, and even more preferably 15 to 50% by weight. If it is less than 5% by weight, the productivity for use in the next step is low, and if it exceeds 60% by weight, it is difficult to say that a slurry with high fluidity is produced.

[0104] The dispersion according to the present invention can also contain additives such as dispersants, resins, antifoaming agents, and auxiliary agents as necessary.The dispersant in the present invention can be appropriately selected and used according to the type of barium titanate particle powder or dispersion medium used, and can be surfactants or polymer dispersants such as 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, and the like, and these can be used alone or in combination of two or more.

[0105] Examples of 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-methacryloyloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-chloropropyltrimethoxysilane; and organopolysiloxanes such as polysiloxane, methylhydrogenpolysiloxane, and modified polysiloxane.

[0106] Organic titanium compounds include isopropyl triisostearoyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, isopropyl tri(N-aminoethyl aminoethyl) titanate, tris(dioctyl pyrophosphate)ethylene titanate, isopropyl dioctyl pyrophosphate titanate, isopropyl tris(dodecylbenzenesulfonyl) titanate, titanium tetra-n-butoxide, and titanium tetra-2-ethylhexoxide. 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.

[0107] Examples of the organic aluminum compound include acetoalkoxyaluminum diisopropylate, aluminum diisopropoxymonoethylacetoacetate, aluminum trisethylacetoacetate, and aluminum trisacetylacetonate.

[0108] Examples of the organic zirconium compound include zirconium tetrakisacetylacetonate, zirconium dibutoxybisacetylacetonate, zirconium tetrakisethylacetoacetate, zirconium tributoxymonoethylacetoacetate, and zirconium tributoxyacetylacetonate.

[0109] Examples of surfactants include anionic surfactants such as fatty acid salts, sulfate ester salts, sulfonate salts, and phosphate ester salts; 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 and alkyl imidazolines, such as alkyl dimethyl amino acetic acid betaines.

[0110] Examples of polymer dispersants include styrene-acrylic acid copolymers, styrene-maleic acid copolymers, polycarboxylic acids and salts thereof.

[0111] The amount of dispersant added depends on the total surface area of ​​the barium titanate particle powder in the dispersion, and may be appropriately adjusted depending on the application of the barium titanate particle powder dispersion and the type of dispersant. Generally, by adding 0.01% by weight to 100% by weight of dispersant to the barium titanate particle powder in the dispersion medium, the barium titanate particle powder can be uniformly and finely dispersed in the dispersion medium and dispersion stability can be improved. The dispersant may be added directly to the dispersion medium, or may be applied to the barium titanate particle powder in advance.

[0112] Specific examples of the present invention will be described below, but the present invention is not limited to these.

[0113] The barium titanate particles of the present invention were evaluated as follows.

[0114] An SEM "S-4300" (manufactured by Hitachi High-Technologies Corporation) was used to observe the surface, shape, and primary particles of the sample.

[0115] 500 primary particles in the obtained image were measured using image analysis particle size distribution measurement software "Mac-View" (manufactured by Mountec Co., Ltd.), and the average primary particle size was calculated from the number average of the primary particle sizes.

[0116] The Ba / Ti composition ratio was measured using a fluorescent X-ray analyzer "Simultix12" (manufactured by Rigaku Corporation).

[0117] The BET specific surface area was measured using a fully automatic specific surface area measuring device "Macsorb HM model-1208 [manufactured by Mountec Co., Ltd.]" after drying and degassing under nitrogen gas at 250°C for 10 minutes.

[0118] The particle size of the aggregated particles in the aqueous solvent was measured using a particle size distribution analyzer "Microtrac MT3300EXII" (manufactured by Microtrac Bell Co., Ltd.) using the laser diffraction / scattering method, or a particle size distribution analyzer "FPAR-1000" (manufactured by Otsuka Electronics Co., Ltd.) using the dynamic light scattering method. ２ When the value exceeded 1 / g, the latter dynamic light scattering method was employed and the analysis was carried out in CONTIN mode.

[0119] The sample was dispersed in 20 mL of a 0.2 wt % aqueous solution of sodium hexametaphosphate dispersant by ultrasonic waves for 5 minutes, and then diluted with pure water to measure the particle size distribution of the aggregated particle diameter. ２ In the case where the dry aggregation between particles was strong in the sample exceeding 1 / g, the sample was a slurry containing the barium titanate particle powder before removing the water used in the solution reaction.

[0120] From the cumulative frequency distribution of the obtained particle size distribution, the D of 50% diameter ５０ and 95% diameter D ９５ D represented by ９５ / D ５０ The value was calculated.

[0121] To identify the crystalline phase of the sample and calculate the crystal structure parameters, measurements were performed using a powder X-ray diffractometer "SmartLab" (Rigaku Corporation).

[0122] The X-ray diffraction pattern was measured through a monochromator under the conditions of Cu-Kα, 40 kV, 200 mA, with a step of 0.02° in the range of 15≦2θ (deg.)≦90, and at a rate of 3 deg. / min.

[0123] Analysis was performed by the Rietveld method to calculate crystal parameters such as lattice constants. The tetragonality, which indicates the crystallinity of barium titanate particles, was expressed as the lattice constant ratio c / a.

[0124] To quantify the amount of impurities in the samples, an internal standard method was employed using a high-frequency inductively coupled plasma optical emission spectrometer (ICP-OES) "Optima 8300" [PerkinElmer Japan Co., Ltd.].

[0125] When the impurity elements Si, S, Cl, Ca, Fe, and Sr were found to be 200 ppm or less, or the impurity alkali metal elements Na and K were found to be 20 ppm or less by ICP-OES, the sample was evaluated as "good."

[0126] The oil absorption of the sample was measured using "S410D" (manufactured by Asahi Research Institute Co., Ltd.).

[0127] 15 g of the sample was weighed and placed in a twin-screw kneader, which was rotated at a constant speed of 200 rpm (=20.94 rad / s angular velocity), and then dibutyl phthalate (DBP), an oil component, was added dropwise at a constant rate of 1 mL / min. The amount of DBP added was plotted on the horizontal axis, and the torque during kneading was plotted on the vertical axis to obtain oil absorption characteristics.

[0128] The obtained oil absorption characteristics were fitted with five or less Gaussian functions to calculate the maximum torque, the oil absorption at the maximum torque, and the area of ​​the oil absorption characteristics. The fitting was performed with the start point of the DBP drop and the end point of the torque value of 0 [Nm].

[0129] The product of the torque [Nm] on the vertical axis and the angular velocity [rad / s] is the power [J / s], and the DBP dripping amount [mL] on the horizontal axis can be converted to time [s] from a dripping rate of 1 mL / min. Therefore, the work [J / g] of the twin-screw kneader per 1 g of sample can be calculated from the area of ​​the oil absorption characteristic.

[0130] In the present invention, the smaller the work [J / g] of the twin-screw kneader, the easier it is to evaluate the dispersibility in a non-aqueous solvent.

[0131] The oil absorption characteristics of carbon black SRB D-6, a standard material, were evaluated using "S410D" with reference to JIS K 6217-4. The sample weight was 8.0 g, the kneader rotation speed was 200 rpm, and the dropping rate was 1 mL / min. The maximum torque was 0.953 Nm, and the oil absorption at the maximum torque was 71.0 mL / 100 g. The oil absorption at 70% torque was 66.7 mL / 100 g.

[0132] The oil absorption characteristics of 12 types of carbon black specified in JIS Z 8901 Test Powder 1 were evaluated using "S410D." The sample weight was 7.5 g, the kneader rotation speed was 200 rpm, and the drop rate was 1 mL / min. The maximum torque was 0.856 Nm, and the oil absorption at maximum torque was 33.3 mL / 100 g. The oil absorption at 70% torque was 32.1 mL / 100 g, and the work of the twin-screw kneader was 14.8 J / g. The sample weight was 7.5 g, the kneader rotation speed was 125 rpm, and the drop rate was 1 mL / min. The maximum torque was 0.896 Nm, and the oil absorption at maximum torque was 33.6 mL / 100 g. The oil absorption at 70% torque was 32.4 mL / 100 g, and the work of the twin-screw kneader was 15.1 J / g.

[0133] The ignition loss of the sample was measured at 1200° C. for 2 hours. 10 g of the sample was weighed, and the weight loss was calculated.

[0134] The moisture content of the cake obtained by dehydrating the slurry containing the mixed titanic acid was calculated by drying 5 g of the cake at 50°C for 12 hours and calculating the weight loss. The ignition loss of the mixed titanic acid cake was calculated by heat treating it at 700°C for 2 hours. The ignition loss of the mixed titanic acid cake was calculated by dividing the weight of the water with the determined moisture content by the weight of the mixed titanic acid TiO ２ ・nH ２ OnH ２ The value of n was calculated assuming that this was due to dehydration of O.

[0135] The samples were evaluated as common materials for the Ni internal electrode layers of MLCC with the cooperation of ECL Co., Ltd. as follows.

[0136] As Ni particles, 0.2 μm size "NFP-201S" (manufactured by JFE Mineral Co., Ltd.) was used.

[0137] A Ni paste was prepared by adding 100 parts by weight of Ni and 20 parts by weight of a sample to a DHTA solvent, a dispersant, and an EC vehicle.

[0138] Here, 30 m ２ In the case of a fine particle sample of 1 / g or more, a dispersant is added to the ethanol solvent, and the sample is then soaked in a 2 mm diameter ZrO ２ The barium titanate particles were pre-dispersed with beads to produce a dispersion containing the barium titanate particles. As described above, the resulting dispersion was added to the sample to make 20 parts by weight, to produce a Ni paste.

[0139] The viscosity of the obtained Ni paste was measured using a Brookfield type viscometer "DV-2" (manufactured by Brookfield) under the conditions of 10 rpm.

[0140] The obtained Ni paste was formed into a film by a doctor blade method to obtain a Ni dry film having a thickness of about 40 μm.

[0141] The density of the dried Ni film was calculated by measuring the shape and weight.

[0142] The surface roughness of the Ni dry film was measured using Surfcom (manufactured by Tokyo Seimitsu Co., Ltd.) A disk of about 14 mm diameter was prepared from the Ni dry film, and the thermal shrinkage of the disk diameter at 600°C to 1200°C was measured.

[0143] [Example 1] Industrial titanium chloride (Ti concentration 16.5 wt%, Cl concentration 31 wt%) was used as the main raw material and diluted with water to prepare a titanium chloride solution. A titanium vessel of approximately 15 L was used for the solution reaction. Barium hydroxide octahydrate (manufactured by Kanto Chemical Co., Ltd., 97% Ba(OH)) was used as the main raw material barium compound. ２ ・8H ２ The neutralizing agent used was industrial grade NaOH.

[0144] Barium hydroxide octahydrate was dissolved in warm water, and the barium carbonate was removed using a filter to prepare a barium hydroxide solution. Titanium chloride was weighed out so that Ti was 5 mol. NaOH was weighed out so that NaOH / Cl was 1.02.

[0145] In the first step, 4 L of NaOH was added dropwise to 4 L of titanium chloride solution diluted with water in an air atmosphere over 1 hour so that the temperature did not exceed 60° C., thereby neutralizing the solution.

[0146] 8 L of orthotitanic acid slurry was obtained without hydrolysis of titanium chloride, and then a portion of the orthotitanic acid was dehydrated in air at 80° C. for 1 hour. The Ti concentration at this time was 0.625 mol / L.

[0147] After that, the mixture was cooled to obtain a mixed titanic acid slurry containing orthotitanic acid and metatitanic acid.

[0148] The obtained slurry was filtered and washed to remove impurity elements such as Na and Cl from the mixed titanic acid, and then 5 g of the cake of mixed titanic acid was dried at 50°C to remove the impurity elements and mixed titanic acid TiO ２ ・nH ２ The n of O was quantified. Furthermore, the X-ray diffraction pattern of the dried sample confirmed the presence of a mixed titanate of metatitanic acid in the crystalline phase of anatase and orthotitanic acid with low crystallinity due to a broad peak.

[0149] The resulting mixed titanate TiO ２ ・nH ２ The n of O was 1.2, and the largest impurity element was Na, at 410 ppm. The remaining mixed titanic acid cake was peptized to form a mixed titanic acid slurry.

[0150] In the second step, the mixed titanic acid slurry and the barium hydroxide solution, each kept at 80°C under a high-purity nitrogen atmosphere, were mixed in a Ba / Ti = 1.5 molar ratio, and the solution reaction was carried out at 80°C for 3 hours to obtain a barium titanate-containing slurry.

[0151] The concentration of Ti was 0.5 mol / L, and the reaction solution volume was 10 L.

[0152] The barium titanate-containing slurry was cooled and concentrated twice by settling, and 5 L of the slurry was hydrothermally treated at 170° C. for 8 hours.

[0153] After filtering, washing with water, and drying and pulverizing the cake, the barium titanate particles of the present invention were obtained.

[0154] Figure 1 shows an SEM image obtained in Example 1. The particle size distribution of the primary particles was measured from the SEM image in Figure 1, and the average primary particle size was calculated.

[0155] The particle size distribution of the aggregated particles in the aqueous solvent obtained by the laser diffraction / scattering method is also plotted in FIG.

[0156] The barium titanate particle powder in Example 1 had an average primary particle diameter of 83 nm and a D １０ is 86.3 nm, D ５０ is 141.6 nm, D ９５ was 262.2 nm.

[0157] The obtained D ９５ / D ５０ The value was 1.9, and the polymer was evaluated as being easily dispersible in aqueous solvents.

[0158] The Ba / Ti composition ratio by fluorescent X-rays was 0.996, and the BET specific surface area was 14.2 m ２ The crystallite size measured by powder X-ray diffraction was 85 nm, the lattice constant ratio c / a was 1.0058, the degree of tetragonality was high, and the crystallinity was high.

[0159] ICP-OES revealed that the impurity elements Si, S, Cl, Ca, Fe, and Sr derived from the main raw materials were 200 ppm or less, and the impurity alkali metal elements Na and K derived from the neutralizing agent were 20 ppm or less, confirming high purity.

[0160] The loss on ignition was 1.2 wt %, confirming high crystallinity.

[0161] FIG. 3 shows the oil absorption characteristics in the measurement of 15 g of sample, with the horizontal axis representing DBP oil absorption and the vertical axis representing torque.

[0162] Fitting was performed using an approximate curve of the sum of five Gaussian functions f1 to f5.

[0163] The sum of the squares of the residuals between the actual measurement data and the approximation curve was 0.0011, and the fitting was performed with high accuracy.

[0164] The obtained oil absorption characteristics showed that the maximum torque was 0.162 N·m, the oil absorption at the maximum torque was 28.3 mL / 100 g, and the work of the twin-screw kneader was 26.7 J / g.

[0165] The barium titanate particles of Example 1 had a low maximum torque and a small oil absorption capacity, and the work of the twin-screw kneader was small, so they were evaluated as being easily dispersible in non-aqueous solvents. [Example 2] The same conditions as in Example 1 were used, except that the hydrothermal treatment temperature was changed from 170°C to 130°C.

[0166] The obtained average primary particle size was 62 nm, and in the oil absorption characteristics, the maximum torque was low, the oil absorption was small, and the work of the twin-screw kneader was small, so it was evaluated as being easily dispersible in non-aqueous solvents.

[0167] Examples 3 to 5 Examples 3 to 5 were carried out with the dehydration reaction temperature in the first step set to 85°C. In Example 3, the hydrothermal treatment temperature was set to 175°C. In Example 4, the hydrothermal treatment temperature was set to 175°C, and after washing with water, the resulting slurry was evaporated to dryness and pulverized. In Example 5, the hydrothermal treatment temperature was set to 125°C. Conditions not described above were the same as in Example 1.

[0168] All barium titanate particle powders had low maximum torque and oil absorption in the oil absorption characteristics, and the work of the twin-screw kneader was small, so they were evaluated as being easily dispersible in non-aqueous solvents.

[0169] [Example 6] The dehydration reaction temperature in the first step was 70°C, the Ba / Ti molar ratio in the second step was 1.3, the Ti concentration was 0.59 mol / L, and the reaction solution was 9 L. The hydrothermal treatment was performed at 105°C for 3 hours, and the other synthesis conditions were the same as in Example 1.

[0170] The obtained barium titanate particle powder had an average primary particle diameter of 35 nm, and because it was a fine particle, it had a low oil absorption capacity in the oil absorption characteristics, a low maximum torque, and little work for the twin-screw kneader, so it was evaluated as being easily dispersible in non-aqueous solvents.

[0171] [Example 7] Half the amount of the mixed titanic acid obtained in the first step of Example 6 (2.5 mol) was mixed with 2.5 mol of metatitanic acid obtained by hydrolysis of titanium chloride according to (Equation C) at pH 2 and a temperature of 60°C to obtain a slurry of 5 mol of mixed titanic acid (n = 0.8). In the second step, the Ti concentration was 0.59 mol / L, and the reaction solution was 9 L. After the solution reaction, the mixture was concentrated 1.75 times and subjected to hydrothermal treatment. The other synthesis conditions were the same as in Example 6.

[0172] The obtained barium titanate particles had an average primary particle diameter of 28 nm, and in terms of oil absorption characteristics, the maximum torque was low, the oil absorption was also small, and the work of the twin-screw kneader was small, so they were evaluated as being easily dispersible in non-aqueous solvents.

[0173] [Example 8] One mole of the mixed titanic acid obtained in the first step of Example 6, which was half the amount, was mixed with 4 moles of metatitanic acid obtained by hydrolysis of titanium chloride according to (formula C) at pH 2 and a temperature of 60°C to obtain a slurry of 5 moles of mixed titanic acid (n = 0.6). The second step and subsequent steps were the same as in Example 7.

[0174] The average primary particle diameter of the obtained barium titanate particles was 27 nm, and the maximum torque was low, the oil absorption was small, and the work of the twin-screw kneader was small, so it was evaluated as easily dispersible in non-aqueous solvents. In addition, the low ignition loss of 2.3 and high crystallinity are thought to be due to the low n value of 0.6 of the mixed titanic acid used.

[0175] [Example 9] The mixed titanic acid (n = 0.8) slurry obtained in the first step of Example 7 was used. In the second step, the Ti concentration was 0.625 mol / L, and the reaction solution was 8 L. After the solution reaction, the slurry was washed with water and concentrated to prepare a 4 L slurry with a conductivity of 25 mS / cm, and then subjected to hydrothermal treatment. The other synthesis conditions were the same as in Example 6.

[0176] The obtained barium titanate particles had an average primary particle diameter of 25 nm, and in terms of oil absorption characteristics, the maximum torque was low, the oil absorption was also small, and the work of the twin-screw kneader was small, so they were evaluated as being easily dispersible in non-aqueous solvents.

[0177] Example 10 The hydrothermal treatment temperature in the second step was set to 85°C, and the other synthesis conditions were the same as those in Example 9.

[0178] The obtained barium titanate particles had an average primary particle diameter of 20 nm, and in terms of oil absorption characteristics, the maximum torque was low, the oil absorption was also small, and the work of the twin-screw kneader was small, so they were evaluated as being easily dispersible in non-aqueous solvents.

[0179] Comparative Example 1 Titanic acid was prepared according to Formula C as follows, with reference to Example 1 of Japanese Patent No. 5765505. However, the main raw materials, neutralizing agent, and other experimental equipment were the same as those in Example 1 of the present invention.

[0180] 4.8 L of pure water was kept at 60° C. in a reaction vessel and exposed to the atmosphere. 2.4 L of titanium chloride solution (Ti: 5.63 mol) and 2.4 L of NaOH (NaOH / Cl=1.0 molar ratio) as a neutralizer were added dropwise at the same time.

[0181] The reaction solution in the reaction vessel was kept at a pH of 1.7 to 2.3 and a temperature of 60° C. throughout, and the titanium chloride solution and NaOH were added dropwise at a constant rate over 2 hours. The Ti concentration after the addition was 0.6 mol / L.

[0182] The resulting slurry was washed with water, and one-sixth of the resulting cake was dried at 120°C and evaluated.

[0183] The dried cake obtained was found to be anatase-type titanium oxide and metatitanic acid by powder X-ray diffraction. ２ ・nH ２ When expressed as 0, n was less than 0.5. In other words, it was not a mixed titanic acid of orthotitanic acid and metatitanic acid according to the present invention.

[0184] However, since the impurity Na content of the dried cake obtained was 500 ppm or less and the purity was high, the second step was carried out as follows.

[0185] The remaining 5 / 6 of the cake obtained was peptized with pure water, exposed to a nitrogen atmosphere, and heated to 85°C, then mixed with a barium hydroxide solution maintained at 85°C. At this time, the Ba / Ti molar ratio was 1.5, and the Ti concentration was 0.5 mol / L. A barium titanate-containing slurry was obtained by concentrating the resulting slurry at 85°C for 3 hours under a nitrogen atmosphere. The resulting slurry was concentrated by sedimentation to twice its original volume, and then subjected to hydrothermal treatment at 170°C for 8 hours.

[0186] As in Example 1, the mixture was filtered, washed with water, dried and pulverized to obtain a barium titanate particle powder.

[0187] The average primary particle diameter of the obtained barium titanate particle powder was 101 nm, D ９５ / D ５０ The value was 1.9, and therefore the product was evaluated as being easily dispersible in aqueous solvents.

[0188] However, in terms of oil absorption characteristics, the maximum torque was high, the oil absorption was relatively large, the work of the twin-screw kneader was large, and it was difficult to say that the compound was easily dispersible in non-aqueous solvents.

[0189] Comparative Example 2 The conditions for Comparative Example 1 were the same as those for Comparative Example 1, except that the hydrothermal treatment temperature was changed from 170°C to 130°C.

[0190] The obtained barium titanate particles had a high maximum torque and a large oil absorption, which meant that the work of the twin-screw kneader was large, and they were not easily dispersible in non-aqueous solvents.

[0191] Comparative Example 3 Barium titanate particles were prepared with reference to Example 6 of JP-A No. 2005-289668, except that the main raw materials, neutralizing agent, and other experimental equipment were the same as those in Example 1 of the present invention.

[0192] The Ti concentration was 0.5 mol / L, and the reaction solution was 10 L. The titanium chloride solution was neutralized with a barium hydroxide solution under the condition of Ba / Ti = 1.5 to obtain orthotitanic acid. This was then mixed with a barium hydroxide solution under the condition of Ba / Ti = 1.5 and reacted at 70°C for 2 hours. The slurry, which had been concentrated by settling to twice its original size, was hydrothermally treated at 200°C for 8 hours, washed with water, dried, and pulverized. The average primary particle diameter of the obtained barium titanate particle powder was 96 nm, D ９５ / D ５０However, the maximum torque was high in the oil absorption characteristics, the oil absorption was also large, and the work of the twin-screw kneader was large, so it was difficult to say that the product was easily dispersible in non-aqueous solvents.

[0193] Comparative Examples 4 and 5 Barium titanate particle powders were prepared with reference to Example 1 of JP 2005-289668 A. Specifically, barium hydroxide and metatitanic acid were used as the main raw materials, and Comparative Example 4 employed a hydrothermal treatment temperature of 190°C, and Comparative Example 5 employed a hydrothermal treatment temperature of 170°C.

[0194] The obtained barium titanate particles had a high maximum torque and oil absorption, and the work of the twin-screw kneader was also large, so that they could not be said to be easily dispersible in non-aqueous solvents.

[0195] Comparative Examples 6 and 7 Comparative Example 6 was carried out under the same conditions as Comparative Example 3, except that the hydrothermal treatment temperature was changed from 200° C. to 105° C. Comparative Example 7 was obtained by washing with water (filtrate conductivity 1 mS / cm end point) and drying without carrying out the hydrothermal treatment in Comparative Example 3.

[0196] Comparative Example 7 D ９５ / D ５０ The value was as high as 18.3, and it was difficult to say that the polymer was easily dispersible in aqueous solvents.

[0197] The barium titanate particles of Comparative Examples 6 and 7 had high oil absorption and required a large amount of work from the twin-screw kneader, so they were hardly easily dispersible in non-aqueous solvents.

[0198] The synthesis conditions are shown in Table 1, and the evaluation results are shown in Table 2. The relationship between oil absorption and average primary particle size is shown in Figure 4. The dotted line indicates the line oil absorption at maximum torque = (36 - 0.08 × average primary particle size) mL / 100 g, which distinguishes between Examples and Comparative Examples. It can be seen that Examples are located below the dotted line, and Comparative Examples are located above the dotted line.

[0199]

[0200] [Evaluation as a common material for Ni internal electrode layers of MLCC] The barium titanate particles obtained in Example 1, Example 2, and Comparative Example 3 were evaluated as a common material for Ni internal electrode layers.

[0201] The results are shown in Table 3.

[0202]

[0203] The viscosity of the Ni pastes of Examples 1 and 2 was reduced by about 10% compared to the viscosity of the Ni paste of Comparative Example 3. It is presumed that the co-material of the easily dispersible barium titanate particle powder according to the present invention reduced the viscosity of the Ni paste.

[0204] The density of the Ni dry film was 5.1 g / cc in all cases, but the surface roughness of the Ni dry film in Examples 1 and 2 was reduced by about 10% compared to the surface roughness of the Ni dry film in Comparative Example 3. It is presumed that the co-material of the easily dispersible barium titanate particle powder according to the present invention improved the dispersibility of Ni.

[0205] The disk diameter thermal shrinkage rates of the dried Ni films of Examples 1 and 2 were approximately 2% to 3% lower from a low temperature of 600°C to a high temperature of 800°C, suppressing the thermal shrinkage of Ni during sintering. Furthermore, even when fired at 1200°C, Examples 1 and 2 exhibited lower thermal shrinkage and superior thermal shrinkage characteristics than Comparative Example 3. This is presumably due to the fact that the co-material of the easily dispersible barium titanate particle powder according to the present invention was more uniformly dispersed among the Ni particles.

[0206] The same 39 m in Example 7 and Comparative Example 6 ２ A sample of 1 / g was evaluated as a co-material for a Ni electrode. Each dispersion containing barium titanate particle powder was obtained by pre-dispersion. To evaluate the dispersion state of the sample in the dispersion, the dispersion was coated and the surface roughness was measured. The surface roughness of the coating film of the dispersions of Example 7 and Comparative Example 6 was 0.012 μm and 0.014 μm, respectively. The dispersion state of the sample in the dispersions prepared under the same conditions was better in Example 7 than in Comparative Example 6.

[0207] Ni pastes were prepared using the dispersions obtained in Example 7 and Comparative Example 6. Although Example 7 had a slightly higher paste viscosity than Comparative Example 6, the density of the dried film was higher and the surface roughness was lower (Table 3). This is because the Ni particles and co-material were better dispersed in Example 7 than in Comparative Example 6. The difference in dispersion state was also confirmed by SEM observation of the dried film. As can be seen from the temperature dependence of the diameter thermal shrinkage rate of the disks listed in Table 3, Example 7 exhibited less thermal shrinkage and better thermal shrinkage characteristics than Comparative Example 6.

[0208] Comparison between the Examples and Comparative Examples reveals that when the barium titanate particles according to the present invention are used as a co-material for the Ni internal electrode layers of an MLCC, an MLCC with high mechanical strength can be obtained.

[0209] These results are presumably due to the fact that the barium titanate particles according to the present invention contain very little unreacted barium and titanium, and furthermore, the surfaces of the particles have high crystallinity.

[0210] The barium titanate particle powder according to the present invention is fine, with an average primary particle diameter of 20 nm to 150 nm, but the particle size distribution of the aggregate particle diameter in aqueous solvents is narrow, making it easily dispersible in aqueous solvents, and it also has a low torque (oil absorption characteristic), making it easily dispersible in non-aqueous solvents. Furthermore, because it has a low ignition loss and high crystallinity, it is suitable for use as a grain growth inhibitor during sintering of Ni internal electrode layers in MLCCs, or as a raw material for high-capacity capacitors or high-transmittance optical films. Therefore, the present invention has high industrial applicability.

Claims

1. The average primary particle diameter is 20 nm or more and 150 nm or less, and the 50% diameter of the cumulative frequency distribution of aggregated particles in an aqueous solvent is D ５０ and 95% diameter D ９５ D represented by ９５ / D ５０ Barium titanate particle powder having a value of 5 or less and a maximum torque of 0.2 N·m or less in its oil absorption characteristics.

2. The barium titanate particle powder according to claim 1, wherein the work of the twin-screw kneader in the oil absorption characteristics is 40 J / g or less.

3. The barium titanate particle powder according to claim 1 or 2, wherein the loss on ignition is 4.0 wt% or less.

4. A method for producing barium titanate particle powder, comprising at least a first step of producing a mixed titanate of orthotitanic acid and metatitanic acid by a solution reaction in an aqueous solvent, and a second step of producing barium titanate by mixing a barium compound at a temperature of 60°C or higher and 105°C or lower.

5. The method for producing barium titanate particle powder according to claim 4, wherein the first step is to dehydrate orthotitanic acid produced with titanium chloride and a neutralizing agent at a temperature of 50°C or higher and 85°C or lower to produce a mixed titanic acid of orthotitanic acid and metatitanic acid.

6. The method for producing barium titanate particle powder according to claim 4, wherein the impurity elements contained in the mixed titanic acid in the first step are each 1000 ppm or less.

7. Mixed titanate is TiO ２ nH ２ The method for producing barium titanate particle powder according to claim 4, wherein when represented as O, n of the mixed titanic acid in the first step is 0.5 ≤ n ≤ 1.

5.

8. The average primary particle diameter is 20 nm or more and 150 nm or less, and D of the 50% diameter of the cumulative frequency distribution of aggregated particles in an aqueous solvent ５０ and D of the 95% diameter ９５ represented by ９５ / D ５０ has a value of 5 or less, and the oil absorption amount at the maximum torque of the oil absorption property is (36 - 0.08 × average primary particle diameter) mL / 100 g or less: barium titanate particle powder.

9. A dispersion comprising barium titanate particle powder according to claim 1 or 8.