JP2018024566A - Composite oxide material containing titanium oxide compound as main component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite oxide material used for an internal electrode layer of a laminated ceramic capacitor or the like which is excellent in dispersibility in a solvent and suppresses adsorption of moisture, surface oxidation and carbonation while being ultrafine particles.SOLUTION: There is provided a composite oxide material made of fine particles containing a titanium oxide compound as a main component, which is surface-treated with a surface treatment agent and has a specific surface area of 20 m/g to 200 m/g and a moisture adsorption amount of 1 wt.% or less when exposed to an environment at a temperature of 25°C and a relative humidity of 50% for 24 hours. Further, the laminated ceramic capacitor comprises an internal electrode layer containing the composite oxide material. The dispersion solution is obtained by dispersing the composite oxide material in a solvent.SELECTED DRAWING: None

Description

  The present invention relates to a composite oxide material mainly composed of a surface-treated titanic acid compound, an internal electrode paste containing the composite oxide material, a multilayer ceramic capacitor including the internal electrode layer, and the composite oxide material as a solvent Relates to a dispersion solution dispersed in

  Typical composite oxide materials based on titanate compounds include potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, aluminum titanate, lithium titanate, etc. There is. These composite oxide materials mainly composed of titanic acid compounds include, for example, friction materials, reinforcing materials, ceramic capacitors, piezoelectric bodies, thermistors, varistors, biocompatible ceramics, refractories, metal processing members, and secondary batteries. Widely used in industry such as electrode negative electrode materials.

  In recent years, in order to meet the demands for reducing the thickness and size of electronic components, fine processing of precision products, improving the physical properties and uniformity of composite materials, etc., it is required to atomize these powder materials. However, particles having a size of several tens of nanometers are easily aggregated and difficult to uniformly disperse, and the surface state is physically and chemically active, which causes quality problems.

  Hereinafter, an example of an internal electrode of a multilayer ceramic capacitor (hereinafter referred to as “MLCC”) will be mainly described. FIG. 1 of Japanese Patent Application Laid-Open No. 2002-234711 (Patent Document 3) shows a typical diagram of a typical MLCC. The internal electrode of the MLCC uses a paste containing an electrode material, screen printing, etc. A pattern is formed with The constituent material of the paste is composed of metal particles typified by nickel, fine particles of barium titanate for adjusting the linear expansion coefficient, a binder, and an organic solvent.

  In Japanese Patent No. 3640511 (Patent Document 1), in order to make the internal electrode of the MLCC thin, it is important that the shape of the particles is spherical together with the size of the nickel powder particles used for forming the internal electrodes. In addition, it is described that when this spherical nickel fine particle is used, the filling density in the electrode paste coating film can be increased, the production of the thin film electrode is easy, and when MLCC is formed, there is an effect of not causing cracks and peeling. .

  JP-A-2015-2250 (Patent Document 2) discloses a good internal electrode paste by controlling the particle size and zeta potential of metal colloid, limiting the pH of the dispersion, and the crystallite size of titanate fine particles. It is described that it produces.

Japanese Patent No. 3640511 Japanese Patent Laid-Open No. 2015-2250 JP 20022347471 A

  However, titanic acid mixed into the internal electrode can be obtained only by using spherical nickel fine powder, controlling the particle diameter of the metal colloid and the zeta potential, limiting the pH of the dispersion, and the crystallite diameter of the barium titanate fine particles. Barium, a binder, and a solvent cannot be mixed uniformly, and there has been a problem that further physical dispersion and labor are required for uniform mixing.

  In the case of the ultrafine particles as described above, if the surface treatment is not performed, the surface oxidation may proceed rapidly, or depending on the material, a large amount of moisture may be adsorbed. For example, in the case of a barium titanate-based powder material mixed with the internal electrode of the MLCC, barium carbonate conversion on the surface of the barium titanate-based powder material proceeds and adversely affects the quality when the MLCC is formed. Further, since a large amount of moisture is adsorbed, there is a problem in that it is aggregated when dispersed in a non-aqueous solvent.

  Accordingly, an object of the present invention is to provide a composite oxide mainly composed of a titanic acid compound that maintains a good dispersion state without agglomeration when mixed with a solvent and is uniformly dispersed even when other electrode materials are mixed. It is to provide material.

  As a result of intensive studies, the present inventors have surface-treated a composite oxide material mainly composed of a titanic acid compound, which is easy to aggregate less than 50 nm, particularly 30 nm or less and is difficult to uniformly disperse in a solvent. By making the surface area in a specific range, we found the effect of maintaining a good dispersion state without agglomeration when mixed with a solvent, and evenly dispersing even if other electrode materials are mixed, and completed the present invention I came to let you. Based on the above knowledge, this invention is comprised as follows.

The composite oxide material according to the present invention is a composite oxide material composed of fine particles mainly composed of a titanate compound, and is surface-treated using a surface treatment agent, and has a specific surface area of 20 m ² / g to ²⁰⁰ m ^2. / G, and the moisture adsorption amount when exposed to an environment of temperature 25 ° C. and relative humidity 50% for 24 hours is 1% by weight or less.

  In the composite oxide material according to the present invention, the average primary particle diameter before the surface treatment calculated from the specific surface area is preferably less than 50 nm in terms of a sphere.

  In the composite oxide material according to the present invention, the surface treatment agent is preferably a silane coupling agent and / or a titanate coupling agent.

  In the composite oxide material according to the present invention, the ratio (B / A) of the weight of the surface treatment agent (B) to the weight of the fine particles (A) mainly composed of a titanic acid compound is 0.01 ≦ B / A ≦. It is preferably 0.30.

  In the composite oxide material according to the present invention, the fine particles mainly composed of a titanate compound are preferably barium titanate.

  The composite oxide material according to the present invention is the most complex oxide material mainly composed of a titanate compound in X-ray diffraction measurement when exposed to an environment of a temperature of 25 ° C. and a relative humidity of 50% for 14 days. The ratio of the largest peak intensity of carbonate to the large peak intensity is preferably 1% or less.

  In the composite oxide material according to the present invention, the surface treatment agent is a silane coupling agent, and the Si content relative to the weight of the composite oxide material mainly composed of a titanate compound is 0.1 to 5. It is preferably 0% by weight.

In the composite oxide material according to the present invention, the surface treatment agent has a general formula R _m SiX _n (I) (R: an organic functional group, X: an alkoxyl group, m = 1 to 3, n = 1 to 3). It is preferable that the total carbon number of R is in the range of C1 to C10.

  A multilayer ceramic capacitor according to the present invention includes an internal electrode layer containing any one of the above complex oxide materials.

  In the multilayer ceramic capacitor according to the present invention, the internal electrode layer preferably further contains a nickel powder material.

  In the multilayer ceramic capacitor according to the present invention, the internal electrode layer is preferably a thin film printed layer.

  In the multilayer ceramic capacitor according to the present invention, the ratio (D / C) of the composite oxide material (D) weight to the internal electrode layer (C) weight is 0.01 ≦ D / C ≦ 0.30. Is preferred.

  The dispersion solution according to the present invention is characterized in that any of the above complex oxide materials is dispersed in a solvent.

  The electrode paste material according to the present invention includes any of the above complex oxide materials.

  The electrode paste material according to the present invention is preferably for an internal electrode of a multilayer ceramic capacitor.

It is a graph which shows the water absorption (moisture adsorption amount) of the barium titanate of the non-surface treatment from which an average primary particle diameter differs. It is a graph which shows the water absorption (moisture adsorption amount) of the barium titanate from which the presence or absence of surface treatment differs (the average primary particle diameter of barium titanate is 16 nm). It is a photograph which shows the state which the barium titanate powder of Example 2 which performed surface treatment, and the barium titanate powder of the comparative example 1 which has not performed surface treatment are disperse | distributing to a solvent.

  Hereinafter, the composite oxide material mainly composed of the surface-treated titanic acid compound of the present invention will be described in detail with specific examples. The present invention is not limited to the embodiments shown below, and various modifications can be made without departing from the technical idea of the present invention.

The composite oxide material according to the present invention is a composite oxide material composed of fine particles mainly composed of a titanate compound, and is surface-treated using a surface treatment agent, and has a specific surface area of 20 m ² / g to ²⁰⁰ m ^2. / G, and the moisture adsorption amount when exposed to an environment of temperature 25 ° C. and relative humidity 50% for 24 hours is 1% by weight or less.

  Examples of composite oxide materials mainly composed of titanate compounds include potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, aluminum titanate, and lithium titanate. . In the composite oxide material according to the present invention, the fine particles mainly composed of a titanate compound are preferably barium titanate.

When the specific surface area of the composite oxide material mainly composed of titanic acid compound exceeds 200 m ² / g, the average primary particle diameter of the titanic acid compound powder material composed of fine particles mainly composed of the titanic acid compound before the surface treatment Is generally 5 nm or less, so that it is difficult to put it to practical use industrially, and the cost may increase.

On the other hand, when the specific surface area of the titanic acid compound powder material comprising fine particles mainly composed of a titanic acid compound is less than 20 m ² / g (average primary particle diameter before surface treatment calculated from the specific surface area is 50 nm in terms of a sphere). Has a high moisture non-adsorption property and carbonation resistance, and therefore may be used as an internal electrode paste as a material having good dispersibility without surface treatment.

Therefore, in the composite oxide material of the present invention, a specific surface area of ^{20m 2} / ^g~200m 2 / g.

  In the composite oxide material according to the present invention, the average primary particle diameter before the surface treatment calculated from the specific surface area is preferably less than 50 nm in terms of a sphere.

  The composite oxide material of the present invention containing a titanic acid compound as a main component is composed of ultrafine particles having an average primary particle diameter before surface treatment calculated from the specific surface area of less than 50 nm in terms of a sphere, but the surface treatment is applied. Therefore, it can be easily dispersed in a non-aqueous solvent. In addition, although the composite oxide material of the present invention is an ultrafine particle, the moisture adsorption amount when exposed to an environment of 25 ° C. and 50% relative humidity for 24 hours is 1% by weight or less. It has a non-adsorbing property for moisture.

  The composite oxide material according to the present invention is the most complex oxide material mainly composed of a titanate compound in X-ray diffraction measurement when exposed to an environment of a temperature of 25 ° C. and a relative humidity of 50% for 14 days. The ratio of the largest peak intensity of carbonate to the large peak intensity is preferably 1% or less.

  By doing so, a composite oxide material having oxidation resistance and carbonation resistance can be provided.

  A multilayer ceramic capacitor according to the present invention includes an internal electrode layer containing any one of the above complex oxide materials.

  For internal electrodes such as MLCC, a conductive paste containing Pt, Pd—Ag alloy, Ni or the like as a conductive component is generally used as a main component, but a base metal such as Ni is often used from the viewpoint of cost.

  Therefore, in the multilayer ceramic capacitor according to the present invention, the internal electrode layer preferably further contains a nickel powder material.

  Moreover, the internal electrode layer used for MLCC etc. is required to be thin.

  Therefore, in the multilayer ceramic capacitor according to the present invention, the internal electrode layer is preferably a thin film printed layer.

  In MLCCs in which internal electrode layers (C) and capacitor layers are alternately stacked, the linear expansion coefficients of the internal electrode layers (C) and the capacitor layers are different during firing. Defects such as weakening occur. Therefore, in MLCC, the internal oxide layer (C) is mixed with a composite oxide material containing a titanic acid compound as a main component of the capacitor layer to adjust the linear expansion coefficient. When the blending ratio (D / C) is less than 0.01 (1%), the linear expansion coefficient does not match and the above-described problems occur. Moreover, when D / C exceeds 0.30 (30%), the function as an electrode, such as an electrode being unable to be formed or an electrostatic capacity falling, will be inhibited.

  Therefore, in the multilayer ceramic capacitor according to the present invention, the ratio (D / C) of the weight of the composite oxide material (D) to the weight of the internal electrode layer (C) is 0.01 ≦ D / C ≦ 0.30. It is preferable that there is 0.01 ≦ D / C ≦ 0.20. That is, the composite oxide material (D) containing a titanic acid compound as a main component with respect to the weight of the internal electrode layer (C) is preferably 1 to 30% by weight, and more preferably 1 to 20%. preferable.

  By doing in this way, the internal electrode layer used for MLCC etc. can make it have characteristics, such as a crack generation | occurrence | production suppression function and peeling generation | occurrence | production suppression function.

  The dispersion solution according to the present invention is characterized in that any of the above complex oxide materials is dispersed in a solvent.

  The electrode paste material according to the present invention includes any of the above complex oxide materials.

  As described above, the composite oxide material of the present invention can be easily and uniformly dispersed in a solvent or the like, and also has high non-adsorption property to water and carbonation resistance. For this reason, it is also suitable as a paste material for internal electrode layers used in MLCCs and the like that require a high packing density in the case of a thin film layer, a high crack generation suppression function and a peeling generation suppression function.

  The electrode paste material according to the present invention is preferably for an internal electrode of a multilayer ceramic capacitor.

  Hereinafter, materials used for the composite oxide material of the present invention will be described.

Composite oxide materials:
Typical composite oxide materials based on titanate compounds include potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, aluminum titanate and lithium titanate. There is. The composite oxide material may be a mixture or solid solution of a plurality of titanates such as barium zirconate titanate, barium titanate titanate, calcium barium zirconate titanate, strontium barium titanate titanate, and the like.

  As a suitable particle size of the composite oxide material, those having an average primary particle diameter of less than 50 nm in terms of a sphere are preferably used, and particularly preferably 10 nm to 20 nm. As a method for producing the material having the particle diameter, a known method may be used, and in general, the material can be synthesized by a wet method such as hydrothermal synthesis. Further, if necessary, the target material may be calcined and pulverized.

Titanic acid compound raw material As a titanium source for synthesizing the titanic acid compound of the present invention, hydrous titanium oxide prepared from titanyl sulfate, titanium tetrachloride, an organic titanium compound, or the like can be used. Hydrous titanium oxide may be converted to anatase by boiling, high temperature and high pressure, or firing. In that case, it is preferable that the particle size of the titanium source is smaller than the titanate compound to be synthesized. A raw material can be selected for the zirconium source as well as the titanium source. In addition, when potassium, barium, strontium, etc. are reacted with a titanium or zirconium source, any raw material can be used as long as it dissolves in the solution.

Surface treatment agent:
In the composite oxide material according to the present invention, the surface treatment agent is preferably a silane coupling agent and / or a titanate coupling agent.

In the composite oxide material according to the present invention, the surface treatment agent has a general formula R _m SiX _n (I) (R: an organic functional group, X: an alkoxyl group, m = 1 to 3, n = 1 to 3, It is preferable that R and X are not necessarily the same functional group.) When the total carbon number of R is large, the organic component in the silane coupling agent increases. When a complex oxide material containing a titanic acid compound as a main component is mixed with, for example, an internal electrode of MLCC, the electrode density after firing decreases when there are many organic components in order to mix the necessary silane coupling agent. May cause harmful effects such as Therefore, the total carbon number of R is preferably in the range of C1 to C10.

  Examples of silane coupling agents include 3-aminopropyltriethoxysilane, hexamethyldisilazane, trimethylmethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, propyl Trimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, decyltrimethoxysilane, octyltriethoxysilane , 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, trifluoropropyltrimethoxysilane and the like.

  Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl borophosphate) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra (2,2-diallyl) Oxymethyl-1-butyl) bis (di-tridecyl) phosphite titanate, bis (dioctyl bisphosphate) oxyacetate titanate, bis (dioctyl bisphosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl Isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate , Isopropyltricumylphenyl titanate, isopropyltri (N-aminoethyl-aminoethyl) titanate, dicumylphenyloxyacetate titanate, diisostearoylethylene titanate, polydiisopropyl titanate, tetranormal butyl titanate, polydinormal butyl titanate, etc. .

  It is desirable that the surface treatment agent is uniformly coated on the titanate compound powder material composed of fine particles mainly composed of titanate compound. In the case where the coating is not uniformly applied, for example, when a composite oxide material mainly composed of these titanate compounds is mixed with the internal electrode material of MLCC, the Si component derived from the silane coupling agent locally builds the glass component. When the internal electrodes are formed during firing, the composite oxide materials may agglomerate with each other (it is assumed that composites and oxide materials that have not been surface-treated are present) or non-uniform conditions may occur. In some cases, the contraction delay effect cannot be expected.

  In the composite oxide material according to the present invention, the ratio (B / A) of the weight of the surface treatment agent (B) to the weight of fine particles (A) of the composite oxide material containing a titanic acid compound as a main component is 0.01 ≦ It is desirable that B / A ≦ 0.30, preferably 0.01 ≦ B / A ≦ 0.20, and more preferably 0.05 ≦ B / A ≦ 0.15. That is, the amount of the surface treatment agent with respect to the composite oxide material containing a titanic acid compound as a main component is 1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 5 to 15% by weight. For this reason, if it is less than 1% by weight, the coating effect of the surface treatment agent is hardly obtained. On the other hand, if the amount exceeds 30% by weight, in the case of MLCC application, silica and titanium are excessively mixed, so that the electrical characteristics of MLCC itself may not be obtained as intended. Moreover, it becomes excessive processing and economical efficiency worsens. In addition, although you may coat | cover with a several surface treating agent, in that case, the total amount of each surface treating agent is applied within the range of 1 to 30 weight%.

  In the composite oxide material according to the present invention, the surface treatment agent is a silane coupling agent, and the Si content relative to the weight of the composite oxide material containing a titanic acid compound as a main component is 0.1-5. The content is preferably 0.0% by weight, more preferably 0.3 to 3.0%, and still more preferably 0.5 to 2.5% by weight.

The reason for this is similar to the method for determining the amount of the surface treatment agent described above, but the effect of the coated Si (here, silane coupling agent) can be applied to, for example, the ML paste Ni paste for internal electrodes. A good dispersion effect can be expected with respect to the non-aqueous solvent. If the amount of Si is as small as less than 0.1%, a good dispersion effect cannot be expected for a non-aqueous solvent. The greater the amount of Si, the better the familiarity with non-aqueous solvents. However, when the amount exceeds the appropriate amount, for example, when used as a Ni paste for MLCC internal electrodes, Si becomes SiO ₂ at the firing stage. _{Since 2} is a low dielectric constant material, when the weight of Si exceeds 5.0%, the dielectric properties of MLCC may be adversely affected. The type and amount of the surface treatment agent are the particle size / amount of Ni powder, the particle size / amount of the composite oxide material mainly composed of titanate compound, the type / amount of solvent, the type / amount of binder. It is appropriately determined depending on the type and amount of the dispersant. However, for example, when the weight of Si is limited to adversely affect the dielectric constant of MLCC, a sufficient moisture adsorption suppression effect cannot be obtained, and it may not be easily dispersed in a non-aqueous solvent. is assumed. In that case, it is possible to combine a surface treatment agent such as a titanate system in a timely manner.

Surface treatment method:
In the present invention, when the surface treatment is performed on the fine particles of the composite oxide material containing a titanic acid compound as a main component, a general treatment method can be applied. That is, after subjecting a target material, a surface treatment agent (coupling agent), and a liquid component such as a solvent as necessary to perform a dispersion treatment such as stirring, the liquid component is separated.

  In the dispersion treatment, an apparatus such as a ball mill, a Henschel mixer, a sand grind mill, or a roll mill can be applied. In order to avoid the influence of air, which will be described later, an apparatus that can perform the treatment in a closed system is preferable.

  In the case of processing to pulverize and disperse using a sphere (media) such as a ball mill or a sand grind mill, for example, zirconia balls can be used as the media. The diameter is generally φ0.1 mm, φ0.5 mm, φ1.0 mm, φ2.0 mm, etc., but it is only necessary to select and use the optimum diameter for processing as needed.

  Examples of the type of solvent are described in “Solvent for Dispersion Solution and Paste” below.

  In addition, since the particle diameter of the material used in this invention is finer than general powder, it is easy to receive to the influence of the water | moisture content or carbon dioxide gas in air | atmosphere. Therefore, when performing the surface treatment, it is necessary to take care not to be affected by the atmosphere as much as possible, for example, the material is sufficiently dried before the treatment, or the work is performed quickly in a low humidity environment.

As a specific surface treatment process, for example, the following procedure is effective.
A composite oxide material mainly composed of a titanic acid compound, a surface treatment agent, φ2 mm zirconia balls, and toluene are put into a planetary ball mill container, the lid is closed, and wet dispersion is performed in a closed system. Next, the slurry is taken out from the planetary ball mill container, separated from the balls using a 1 mm mesh, and the slurry is recovered. The recovered slurry is put into a drier set at 120 ° C., and the liquid component is removed to make a dry powder. The dry powder is crushed using a mortar and passed through an approximately 300 μm mesh to remove impurities and agglomerates.

Examples of solvent solvents used in dispersion solutions and pastes include alcohols, acetone, ethyl acetate, butyl acetate, methyl ethyl ketone, petroleum ethers, mineral spirits, toluene, other hydrocarbon solvents, butyl carbitol, terpineol, dihydroterpineol, Acetate series such as butyl carbitol acetate, dihydroterpineol acetate, dihydrocarbyl acetate, carbyl acetate, terpinyl acetate, linalyl acetate, dihydroterpinyl propionate, dihydrocarbyl propionate, isobornyl propionate And propionate solvents such as ethyl cellosolve and butyl cellosolve, aromatics, and diethyl phthalate. In addition, the solvent is selected in a timely manner depending on the application and purpose.

Although it will not specifically limit if it melt | dissolves in a binder paste solvent, What is necessary is just to use resin, such as methylcellulose, ethylcellulose, and polyvinyl butyral.

  According to the present invention, even if ultrafine particles mainly composed of a titanic acid compound are used as the composite oxide material, the surface treatment is performed, so that the composite oxide material is not only easily dispersed in a non-aqueous solvent, but also has a surface Effective in preventing carbonation and moisture adsorption. In addition, if the composite oxide material mainly composed of the surface-treated titanic acid compound of the present invention is used, uniform mixing with other materials, easy dispersion in a solvent, suppression of active surface oxidation and carbonation, moisture adsorption It is expected to contribute to the improvement of the quality of each material including electronic materials.

  Specifically, if an appropriate amount of the composite oxide material mainly composed of the surface-treated titanic acid compound of the present invention is mixed with the internal electrode paste of MLCC, the uniformity of the paste, after the paste is formed into a coating film It is expected that the dry surface has a low roughness (suitable for thinning) and contributes greatly to thinning and quality, such as a shrinkage delay effect due to heat during firing.

  That is, the MLCC internal electrode paste mixed with a composite oxide material mainly composed of a titanic acid compound surface-treated with this surface treatment agent has a low surface roughness when formed into a coating film and is laminated. It is an excellent material that has the effect of reducing unevenness at the time, and also has the effect of delaying shrinkage during firing.

1. Creation of titanium hydroxide
Tetrahydrate and 2.86 kg (16.4% contained as titanium) hydrolyzing titanium tetrachloride aqueous solution of titanium chloride aqueous solution was stirred in for 30 minutes in pure water 11.5 kg. A 6% aqueous sodium hydroxide solution was added to the aqueous solution at a constant rate with a roller pump until the pH reached 7.0, thereby obtaining a white slurry. This slurry was filtered and washed with water to obtain a hydrous titanium oxide cake having a solid content of 11%.
・ Hydrolysis of aqueous solution of titanyl sulfate, etc. 8% sodium hydroxide aqueous solution was added to 17.5 kg of aqueous solution of titanyl sulfate (containing 3.3% as titanium) at a constant rate until the pH reached 7.0 with a roller pump. A white slurry was obtained. This slurry was filtered and washed with water to obtain a hydrous titanium oxide cake having a solid content of 11%.

2. Preparation of barium titanate powder In a vessel equipped with a reflux tube, 486 g of barium hydroxide and 500 g of pure water were mixed and boiled and refluxed at 100 ° C. At this time, nitrogen gas was purged into the container to prevent the formation of barium carbonate.
800 g of the hydrous titanium oxide cake obtained above was sampled, 250 g of pure water was added to form a slurry, which was slowly added to the barium hydroxide solution, and refluxed for 1.5 hours. After the reaction, the slurry was filtered and washed with water, the Ba / Ti ratio was adjusted, and then dried to obtain a barium titanate powder.
For the average primary particle diameter of the barium titanate powder, the methods described in Examples and Comparative Examples of JP-A-6-48734 were applied. That is, it was adjusted by controlling the reaction conditions (Ba / Ti ratio, concentration, etc.). The Ba / Ti ratio of the produced barium titanate powder can be adjusted as appropriate.
Manufacturing Method of MLCC Ni Electrode for Internal Electrode (1) Slurry in which a composite oxide material mainly composed of a surface-treated titanic acid compound, a solvent used in the electrode paste, and a dispersing agent are mixed and dispersed using a bead mill. (A) is produced.
(2) The Ni fine powder and the binder are mixed in the slurry of (a) and then kneaded in a three-roll mill.

Example 1
Barium titanate was prepared using a titania cake prepared by hydrolyzing a titanium tetrachloride aqueous solution.
After mixing 100 g of barium titanate powder having an average primary particle diameter of 30 nm calculated from the specific surface area with a spherical equivalent value in 200 g of toluene, 6% by weight of isobutyltrimethoxysilane was added to the barium titanate powder. Slurried. This slurry was wet dispersed in a planetary ball mill, distilled under reduced pressure, dried and crushed to obtain barium titanate powder surface-treated with isobutyltrimethoxysilane.

Example 2
In place of the barium titanate powder used in Example 1, surface-treated barium titanate powder was treated in the same manner as in Example 1 except that barium titanate powder having an average primary particle size of 16 nm was used. Got.

Example 3
In Example 2, a surface-treated barium titanate powder was obtained by performing the same treatment as in Example 2 except that 5% by weight of isobutyltrimethoxysilane and 5% by weight of isopropyltriisostearoyl titanate were mixed. .

Example 4
In place of the titania cake obtained by hydrolyzing the titanium tetrachloride aqueous solution used in Example 1, a titanic acid surface-treated by performing the same treatment as in Example 1 except that a titania cake obtained by hydrolyzing a titanyl sulfate aqueous solution was used. Barium powder was obtained.

Example 5
Instead of the barium titanate powder used in Example 1, a treatment similar to that in Example 1 was performed except that isobutyltrimethoxysilane was treated with 10% by weight using a barium titanate powder having an average primary particle size of 12 nm. To obtain a surface-treated barium titanate powder.

Example 6
The same treatment as in Example 1 except that instead of the barium titanate powder used in Example 1, barium titanate powder having an average primary particle size of 6 nm was treated with 12% by weight of isobutyltrimethoxysilane. To obtain a surface-treated barium titanate powder.

Example 7
A barium titanate powder surface-treated by the same treatment as in Example 2 except that 5% by weight of isobutyltrimethoxysilane and 5% by weight of 3-methacryloxypropyltrimethoxysilane were mixed in Example 2. Obtained.

Example 8
The surface-treated titanic acid was treated in the same manner as in Example 2 except that 7.5% by weight of isobutyltrimethoxysilane and 7.5% by weight of 3-methacryloxypropyltrimethoxysilane were mixed in Example 2. Barium powder was obtained.

Example 9
The surface-treated titanic acid was treated in the same manner as in Example 2 except that 10.0% by weight of isobutyltrimethoxysilane and 10.0% by weight of 3-methacryloxypropyltrimethoxysilane were mixed in Example 2. Barium powder was obtained.

Example 10
In place of the barium titanate powder used in Example 1, strontium titanate powder which was surface-treated by the same treatment as in Example 1 except that strontium titanate powder having an average primary particle size of 30 nm was used. Got.

Example 11
In Example 2, a surface-treated barium titanate powder was obtained by performing the same treatment as in Example 2 except that 6% by weight of 3-aminopropyltriethoxysilane was treated.

Example 12
In Example 5, a surface-treated barium titanate powder was obtained by performing the same treatment as in Example 5 except that 28% by weight of methyltrimethoxysilane was treated.

Example 13
A composite oxide slurry having a titanic acid compound as a main component was prepared using a bead mill with 200 g of barium titanate powder surface-treated with isobutyltrimethoxysilane obtained in Example 2, 360 g of terpineol, and 6 g of a dispersant. . The beads were removed, 300 g of Ni particles with an average particle diameter of 200 nm, 175 g of terpineol, and 150 g of ethylcellulose solution (adjusted to 10% with terpineol) were mixed in a plastic container and kneaded with three rolls. The paste was adjusted. The paste was coated on a PET film using an applicator (gap thickness 25 μm), dried at 125 ° C. for 10 minutes, and then the surface roughness of the electrode film with a 100 μm square area was measured. As a result of measurement, the surface roughness was 0.06 μm.

  The paste was prepared using barium titanate powder that was not surface-treated with isobutyltrimethoxysilane, and the surface roughness after coating and drying by the same treatment was 0.15 μm (Comparative Example 6). The MLCC internal electrode paste produced using the surface-treated barium titanate powder was found to be a good paste with low surface roughness.

  Furthermore, after drying this paste at 150 ° C., the dried powder was mixed in a mortar. The dried powder was degreased (500 ° C.), molded into pellets, and reduced and fired. As a result, the shrinkage at 700 ° C. was 1% and the shrinkage at 1000 ° C. was 4%. In addition, the shrinkage rate measured the shrinkage rate from the time of pellet molding.

  When the paste using barium titanate powder that has not been surface-treated with isobutyltrimethoxysilane is dried, degreased, and reduced and fired, the thermal shrinkage rate is 1.5% at 700 ° C and the shrinkage rate is 8% at 1000 ° C. It was found that if the paste using the barium titanate powder surface-treated with isobutyltrimethoxysilane of this example is used, the effect of delaying shrinkage due to heat can be obtained.

Comparative Example 1
In Example 2, the treatment was carried out without adding isobutyltrimethoxysilane to obtain 16 nm barium titanate powder that was not surface-treated.

Comparative Example 2
A surface-treated barium titanate powder was obtained by performing the same treatment as in Example 2 except that 0.6% by weight of isobutyltrimethoxysilane was added in Example 2.

Comparative Example 3
In Example 1, the treatment was performed without adding isobutyltrimethoxysilane to obtain a 30-nm barium titanate powder that was not surface-treated.

Comparative Example 4
In Example 1, instead of 30 nm barium titanate, barium titanate having an average primary particle size of 50 nm was used, and the treatment was performed without adding isobutyltrimethoxysilane, and the surface-treated 50 nm barium titanate powder was not used. Got.

Comparative Example 5
In Example 1, barium titanate having an average primary particle size of 100 nm was used instead of 30 nm of barium titanate, and the treatment was performed without adding isobutyltrimethoxysilane. Got.

Comparative Example 6
An electrode film was prepared in the same manner as in Example 11 except that barium titanate powder that was not surface-treated with isobutyltrimethoxysilane in Example 11 was used. The surface roughness of the produced electrode film was 0.15 μm. Further, the paste was dried, degreased (500 ° C.), molded into pellets, and fired. As a result, the shrinkage at 700 ° C. was 1.5%, and the shrinkage at 1000 ° C. was 8%.

3. Evaluation of barium titanate powder Examples 1 to 7 and Comparative Examples 1 to 5 were carried out by the measurement methods described below, by dispersibility in terpineol, which is a kind of monoterpene alcohol, The intensity ratio of X-ray diffraction was measured.

Average primary particle size:
QUADRASURB S1 (manufactured by Cantachrome Co., Ltd.) was used as the measuring device, and the specific surface area was measured using nitrogen as the measurement gas. From the measured value of the specific surface area, the average primary particle diameter was calculated as a spherical conversion value using the following formula.
D = 6000 / (S × ρ)
Here, D represents an average primary particle diameter (nm), S represents a specific surface area value (m ² / g), and ρ represents a density (g / cm ² ). The density was 6.02 g / cm ³ which is the theoretical density of barium titanate.

Dispersibility in terpineol:
10 g of terpineol was added to a 50 ml screw tube, 1 g of the powder obtained in Examples 1 to 7 and Comparative Examples 1 to 5 was added as a sample, and shaken 50 times. After standing for 4 hours, the sedimentation condition of the powder was visually observed, and the dispersibility was judged as follows.
○: almost no sedimentation △: slight sedimentation ×: almost all sedimentation

Moisture adsorption:
The powder obtained in Examples 1 to 12 and Comparative Examples 1 to 5 was collected as a measurement sample in a 1 g weighing bottle, dried in a dryer at 120 ° C. for 4 hours, and then allowed to cool in a desiccator. The sample after being allowed to cool was exposed to an environment of 25 ° C. and a relative humidity of 50% for 24 hours, and the moisture adsorption amount (%) was calculated from the weight increase.

X-ray diffraction intensity ratio:
The powders obtained in Examples 1 to 12 and Comparative Examples 1 to 5 were exposed to an environment of 25 ° C. and 50% relative humidity as a measurement sample for 14 days, followed by X-ray diffraction measurement. The ratio (%) of the maximum peak intensity of the carbonate when the peak intensity was 100 was calculated. The measuring apparatus used was an X-ray diffraction measuring apparatus X PERT PRO (manufactured by PANALYTICAL).

Ba / Ti ratio:
As a measuring device, a fluorescent X-ray measuring device Spectris AKIOS-4KW type (manufactured by PANALYTICAL) was used, and a Ba / Ti ratio was calculated from a quantitative analysis result of fluorescent X-rays.
The Sr / Ti ratio is not measured.

Surface roughness measurement method Ni electrode paste mixed with Ni fine powder / barium titanate powder / dispersant / binder is coated on a PET film using an applicator (gap thickness 25 μm) and dried. The surface roughness of was measured.

Method for Measuring Thermal Shrinkage of Paste Dry Powder The prepared Ni electrode paste was dried at 150 ° C. and then crushed in a mortar for 10 minutes. The organic matter was degreased at 500 ° C. at a heating rate of 5 ° C./min in the air. The obtained degreased powder was molded into a cylindrical pellet having a diameter of 6 mm, heated to 700 ° C. and 1,000 ° C. at a heating rate of 5 ° C./min in nitrogen gas, and the shrinkage ratio of the molded pellets Was measured.

Table 1 shows the measurement results of the above characteristics of the titanate compound powders obtained in Examples 1 to 12 and Comparative Examples 1 to 5.

  In the above Examples and Comparative Examples, Comparative Examples 1, 3 to 5 having different average primary particle diameters are used to examine in detail how the average primary particle diameter affects the water absorption rate (moisture adsorption amount) of barium titanate. FIG. 1 shows the measurement results of the water absorption rate of untreated surface-treated barium titanate.

  Further, in order to investigate in detail how the presence or absence of surface treatment affects the water absorption rate of barium titanate, the barium titanate and silane cups of Example 2 subjected to surface treatment using a silane coupling agent were used. Measurement results of water absorption (moisture adsorption amount) of barium titanate of Example 3 in which surface treatment was performed using both a ring agent and a titanate coupling agent and barium titanate in Comparative Example 1 in which surface treatment was not performed Is shown in FIG.

  As an example showing the dispersibility in terpineol, the barium titanate powder of Example 2 subjected to surface treatment and the barium titanate powder of Comparative Example 1 not subjected to surface treatment were shaken 50 times. FIG. 3 shows the dispersion state after standing for 4 hours.

4). As can be seen from FIG. 1, the barium titanate powder that has not been subjected to surface treatment has a larger amount of moisture adsorption as the average primary particle size is smaller. This is considered to be due to the effect that the specific surface area increases as the particle size of the powder decreases. For this reason, when the average primary particle diameter of the barium titanate powder not subjected to the surface treatment becomes larger than 100 nm, the specific surface area becomes small. As a result, the moisture adsorption amount becomes almost 0 wt% regardless of the exposure time. The significance of applying surface treatment to the barium powder is diminished. In addition, barium titanate powder having an average primary particle size larger than 100 nm is unsuitable for use as a paste material for the internal electrode layer of MLCC which is being thinned. .

  As is clear from FIG. 2, the surface-treated barium titanate powder uses a titanate coupling agent even when a silane coupling agent is used as the surface treatment agent (Example 2). (Example 3), the moisture adsorption amount was suppressed to 1 wt% or less even when exposed to an environment with a temperature of 25 ° C. and a relative humidity of 50% for more than 24 hours and longer than 5000 minutes. On the other hand, the moisture adsorption amount of the barium titanate powder of Comparative Example 1 that was not surface-treated had already exceeded 1 wt% after 24 hours.

Further, as is clear from Table 1, it is a composite oxide material composed of fine particles mainly composed of barium titanate, which is surface-treated using a surface treatment agent, and has a specific surface area of 20 m ² / g to ²⁰⁰ m ^2. / G, and the composite oxide powders of Examples 1 to 12 having a moisture adsorption amount of 1% by weight or less when exposed to an environment of 25 ° C. and 50% relative humidity for 24 hours are Comparative Examples 1 to 1. Compared with 5, it showed high dispersibility in the solvent.

  As will be understood with reference to FIG. 3, when the moisture adsorption amount is increased, the particles are aggregated without being uniformly dispersed when dispersed in a non-aqueous solvent (here, terpineol). Further, if the powder is left as it is without performing effective surface treatment, a powder having a small particle diameter (= large specific surface area) generates carbonate due to its surface activity. There is a negative effect of adversely affecting the quality of the blended final product. It is considered that this is because the particle surface having a large specific surface area is in a highly active state, resulting in moisture adsorption and carbonate formation.

  In this example, attention is paid to modifying the particle surface as a solution to the problem, and moisture adsorption is reduced by applying a surface treatment of preferably 1 to 30 wt% on the target powder using a coupling agent. It was confirmed that the formation of carbonate, which is a different composition, was suppressed. By using the composite oxide material to which the present invention is applied to an electronic component or the like, it is possible to expect high quality and high reliability that have not been obtained conventionally.

It should be considered that the embodiments and examples disclosed above are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and includes all modifications and variations within the scope and meaning equivalent to the scope of claims.

Claims (15)

A composite oxide material composed of fine particles mainly composed of a titanate compound,
Surface treated with the surface treatment agent, the specific surface area of ^{20m 2} / ^g~200m 2 / g, the temperature 25 ° C., the water adsorption during exposure 24 hours under a relative humidity of 50% 1% A composite oxide material that is:   The composite oxide material according to claim 1, wherein the average primary particle diameter before the surface treatment calculated from the specific surface area is less than 50 nm in terms of a sphere.   The composite oxide material according to claim 1, wherein the surface treatment agent is a silane coupling agent and / or a titanate coupling agent.   The ratio (B / A) of the weight of the surface treatment agent (B) to the weight of the fine particles (A) containing a titanic acid compound as a main component is 0.01 ≦ B / A ≦ 0.30. 4. The composite oxide material according to any one of up to 3.   The composite oxide material according to any one of claims 1 to 4, wherein the fine particles mainly composed of the titanate compound are barium titanate.   In X-ray diffraction measurement when exposed to an environment of temperature 25 ° C. and relative humidity 50% for 14 days, the highest peak intensity of carbonate relative to the highest peak intensity of the complex oxide material mainly composed of titanate compound The composite oxide material according to claim 5, wherein the ratio of is 1% or less. The surface treatment agent is a silane coupling agent,
The composite oxidation according to any one of claims 1 to 6, wherein the content of Si is 0.1 to 5.0% by weight with respect to the weight of the composite oxide material containing a titanic acid compound as a main component. Material. The surface treatment agent is a silane coupling agent represented by the general formula R _m SiX _n (I) (R: organic functional group, X: alkoxyl group, m = 1-3, n = 1-3), The composite oxide material according to claim 1, wherein the total carbon number of R is in the range of C1 to C10.   A multilayer ceramic capacitor comprising an internal electrode layer containing the composite oxide material according to any one of claims 1 to 8.   The multilayer ceramic capacitor according to claim 9, wherein the internal electrode layer further includes a nickel powder material.   The multilayer ceramic capacitor according to claim 9 or 10, wherein the internal electrode layer is a thin film printed layer.   The ratio (D / C) of the composite oxide material (D) weight to the internal electrode layer (C) weight is 0.01 ≦ D / C ≦ 0.30. The multilayer ceramic capacitor according to any one of claims.   A dispersion solution, wherein the composite oxide material according to any one of claims 1 to 8 is dispersed in a solvent.   The paste material for electrodes containing the complex oxide material of any one of Claim 1- Claim 8. The electrode paste material according to claim 14, which is used for an internal electrode of a multilayer ceramic capacitor.