JP6972748B2 - Method for manufacturing composite oxide particles, composite oxide powder, dispersion liquid and dielectric for capacitors - Google Patents

Description

The present application discloses a method for producing composite oxide particles having a perovskite-type crystal phase.

Composite oxide particles having a perovskite-type crystal phase are widely used as dielectrics, optical materials, and the like by taking advantage of their high dielectric constant and refractive index. In particular, a composite oxide having a small crystallite diameter and a composite oxide having a small particle size are required in view of dispersibility in a matrix resin and the development of ultra-high functionality due to the quantum size effect.

A composite oxide having a perovskite-type crystal phase can be synthesized by, for example, a general solid-phase method, a solvothermal method, or the like, but such a general method has a sufficient crystallite size and particle size. It is difficult to produce small particles. In this regard, various methods for producing composite oxide particles having a small crystallite diameter and particle size have been proposed.

For example, Patent Document 1 discloses a technique for synthesizing perovskite-type composite oxide particles while coexisting with a silane coupling agent in a solvothermal method using water and an organic solvent. As described above, it is considered that the chemical stability of the composite oxide can be enhanced and the composite oxide particles having a small particle size can be obtained by coexisting the silane coupling agent in the solvothermal method.

Further, Patent Document 2 discloses a technique for synthesizing perovskite-type composite oxide particles while coexisting amines such as oleylamine in a solvothermal method using an oxygen-containing organic solvent. As described above, it is considered that the coexistence of amines in the solvothermal method can suppress the coarsening of the crystals of the composite oxide, and can obtain composite oxide particles having a small crystallite diameter and particle size.

Japanese Unexamined Patent Publication No. 2013-177259 Japanese Unexamined Patent Publication No. 2007-269601

In the technique disclosed in Patent Document 1, the element M (for example, Ti etc.) constituting the B site is intentionally excessively added to the element A (for example, Ba etc.) constituting the A site of the perovskite type crystal phase. It is contained, and there is a problem that impurities other than the perovskite type crystal phase (for example, TiO ₂ ) are easily generated on the surface of the particles and inside the particles. In addition, in the technique disclosed in Patent Document 1, since the particles contain a component derived from a silane coupling agent, there is a possibility that the dielectric constant and the refractive index inherent in the perovskite-type composite oxide may be adversely affected.

On the other hand, as disclosed in Patent Document 2, when the element A constituting the A site of the perovskite type crystal structure is excessive than the element M constituting the B site at the stage of charging the raw material, the element A finally becomes excessive. In the obtained particles, there is a problem that _{impurities (BaCO 3, etc.) derived from the element A are easily generated on the surface and the inside thereof.} In Patent Document 2, after obtaining composite oxide particles by the sorbothermal method, impurities are tried to be removed by washing the particles with ethanol. However, according to the new findings of the present inventors, ethanol washing is performed. Impurities cannot be sufficiently removed by itself, and the ratio (A / M) of the element A to the element M is set to 1 ideal for a perovskite type crystal in the finally obtained composite oxide particles. It is difficult to get close.

As a result of diligent studies to solve the above problems, the present inventors obtained solid content by the sorbothermal method, and then treated the solid content with an acid solution of less than 5% by mass to finally obtain the solid content. In the composite oxide particles obtained in the above, the ratio (A / M) of the element A to the element M can be brought close to the ideal 1 as a perovskite, and the average crystallite diameter can be made extremely small. Was found.

Based on the above findings, the present application is one of the means for solving the above problems.
Selected from the group consisting of one or more elements A selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn, and the group consisting of Ti, Zr, W, Nb, Hf, and Sn. A method for producing a composite oxide particle containing at least one element M and having a perovskite-type crystal phase composed of the element A, the element M and oxygen, and containing at least the element A. The first step of mixing the precursor and the precursor containing the element M so that the element A is excessive with respect to the composition of the perovskite type crystal phase to obtain a reaction solution, and the reaction solution. The second step of obtaining a synthetic liquid containing a solid content by subjecting it to the sorbothermal method, and the third step of obtaining composite oxide particles by treating the solid content with an acid solution of less than 5% by mass. Disclosed is a method for producing composite oxide particles.

In the production method of the present disclosure, it is preferable to recover the solid content after mixing methanol with the synthetic solution in the third step, and treat the recovered solid content with the acid solution.

In the production method of the present disclosure, it is preferable that in the third step, the solid content is treated with the acid solution and recovered, and then the recovered solid content is treated with ethanol.

The present application is one of the means for solving the above problems.
A composite oxide powder comprising a plurality of composite oxide particles, wherein the composite oxide particles are one or more selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn. A perovskite-type crystal containing the element A and one or more elements M selected from the group consisting of Ti, Zr, W, Nb, Hf, and Sn, and composed of the element A, the element M, and oxygen. The composite oxide powder has a phase, and the molar ratio (A / M) of the element A to the element M is 0.85 or more and 1.20 or less in the composition of the entire composite oxide powder. Disclosed is a composite oxide powder having an average crystallite diameter of 10 nm or less in the perovskite type crystal phase.

The composite oxide powder of the present disclosure preferably has an average dispersed particle size of 50 nm or less.

The composite oxide powder of the present disclosure can be dispersed in a solvent to prepare a dispersion liquid, for example. That is, it is a dispersion liquid containing the composite oxide powder of the present disclosure and a solvent.

The composite oxide powder of the present disclosure can be applied to various uses. For example, a dielectric for a capacitor including the composite oxide powder of the present disclosure can be mentioned.

According to the production method of the present disclosure, the solid content obtained by a predetermined sorbothermal method is treated with an acid solution of less than 5% by mass to obtain a perovskite-type ratio (A / M) of element A to element M. Composite oxide particles having an extremely small average crystallite diameter can be obtained while being able to approach 1 which is ideal as a crystal.

It is a figure for demonstrating the flow of the manufacturing method (S10) of a composite oxide particle. It is a figure which shows the powder X-ray diffraction measurement result of Example 1. FIG. It is a figure which shows the powder X-ray diffraction measurement result of the comparative example 1. FIG. It is a figure which shows the powder X-ray diffraction measurement result of the comparative example 2.

The embodiments described below are examples (representative examples) of embodiments of the present invention, and the present invention is not limited thereto. That is, the present invention can be arbitrarily modified and implemented without departing from the gist thereof.

1. 1. Method for Producing Composite Oxide Particles The method for producing composite oxide particles (S10) shown in FIG. 1 is one or more selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn. A perovskite-type crystal containing element A and one or more elements M selected from the group consisting of Ti, Zr, W, Nb, Hf, and Sn, and composed of the element A, the element M, and oxygen. A method for producing a composite oxide particle having a phase, wherein at least a precursor containing the element A, a precursor containing the element M, amines, and an oxygen-containing organic solvent are used in the perovskite type. A synthetic solution containing a solid content by subjecting the reaction solution to the sorbothermal method in the first step (S1) of mixing the element A so as to have an excess amount with respect to the composition of the crystal phase to obtain a reaction solution. The second step (S2) for obtaining composite oxide particles by treating the solid content with an acid solution of less than 5% by mass is provided.

1.1. First step (S1)
In the first step, at least the precursor containing the element A and the precursor containing the element M are mixed to obtain a reaction solution. In particular, a precursor containing element A, a precursor containing element M, amines, and an oxygen-containing organic solvent are mixed so that the amount of element A is excessive with respect to the composition of the perovskite-type crystal phase. It is preferable to obtain a reaction solution. The reason why the element A is excessive is as follows. Since element M such as Ti is usually more reactive than element A such as Ba, an oxide derived from element M (titanium oxide, etc.) other than the target perovskite type crystal phase in the composite oxide particles. Is generated in a large amount, and the element A falls off due to a subsequent cleaning operation or the like, and as a result, the ratio of the element M becomes higher than that of the element A. Therefore, it is considered preferable to make the element A an excessive amount in advance.
The reaction solution may contain other components as long as the above problems can be solved. For example, other additives may be contained, if necessary. In this case, a reaction solution in which precursors, amines and additives are dissolved or dispersed in an oxygen-containing organic solvent is obtained.

1.1.1. As the precursor containing the element A and the precursor containing the element M, any substance can be used as long as the desired composite oxide particles can be obtained. That is, an appropriate metal element or metal compound containing a metal element constituting a desired composite oxide particle can be arbitrarily selected and used. Although the elements described above can be used as the element A and the element M, in order to obtain the metal oxide composite particles having a ratio of the element A / element M close to 1 by the method described later, Ba is preferable. , Sr, Ca, Mg and Pb, and more preferably, the element A is an alkaline earth metal, that is, one or more selected from Mg, Ca, Sr and Ba. Of these, Ba is particularly preferable. On the other hand, the element M is preferably one or more selected from the group consisting of tetravalent metal elements, that is, Ti, Zr, Sn and Hf, and more preferably from Ti, Zr and Hf for the same reason. It is one or more selected from the group, more preferably Ti and / or Zr, and particularly preferably Ti.

Examples of precursors include metal chlorides, metal acetates, metal alkoxides, metal hydroxides and the like. Among these, metal alkoxide, metal acetate, and metal hydroxide are preferable in consideration of impurities (for example, chloride) produced as a by-product. Among these, although there is no particular limitation, as a preferable combination of precursors, a combination of a metal hydroxide containing the element A and a metal alkoxide containing the element M is preferable.

Suitable examples of precursors containing element A are barium ethoxydo, barium-2-ethylhexanoate, barium isopropoxide, barium methoxypropoxide, barium-2,4-pentandionate hydrate, barium-. 2,2,6,6-tetramethyl-3,5-heptanionate, barium-2,2,6,6-tetramethyl-3,5-heptangeonate hydrate, barium titanium double alkoxide, barium zirconium Double alkoxide, barium hydroxide octahydrate,

Bis (2,2,6,6-tetramethyl-3,5-heptanionate) strontium hydrate, bis (2,2,6,6-tetramethyl-3,5-heptanionate) strontium tetraglime Additives, bis (2,2,6,6-tetramethyl-3,5-heptangeonate) strontium triglime adduct, strontium titanium double alkoxide, strontium zirconium double alkoxide, strontium hydroxide, strontium acetate, strontium-2 -Ethylhexanoate, strontium isopropoxide, strontium methoxypropoxide, strontium-2,4-pentandionate, strontium-2,2,6,6-tetramethyl-3,5-heptandionate and the like can be mentioned. ..

Alkoxides and hydroxides are also preferable examples for the elements other than barium and strontium mentioned above.

Preferable examples of the precursor containing the element M are titanium methoxydo, titanium ethoxydo, titanium-di-n-butoxide (bis-2,4-pentandionate), titanium-diisopropoxide (bis-2, 4-Pentandionate), Titanium-diisopropoxide (bisethylacetacetate), Titanium-2-hexoxyside, Titanium-n-butoxide, Titaniumisopropoxide, Titaniummethoxypropoxide, Titanium-n-nonyloxide, Titanium oxide (Bistetramethylpentandionate), Titanium-n-propoxide, Titanium stearyl oxide, Titanium triisostearyl isopropoxide, Titanium trimethylsiloxide,

Zirconium-n-butoxide, zirconium-t-butoxide, zirconium-di-n-butoxide (bis-2,4-pentandionate), zirconium-di-isopropoxide (bis-2,2,6,6,- (Tetramethyl-3,5-heptangeonate), zirconium ethoxide, zirconium propoxide, zirconium-2-ethylhexanoate, zirconium-2-ethylhexoxide, zirconium isopropoxide, zirconium-2-methyl-2 -Butoxide, zirconium-2,4-pentandionate, zirconium-n-propoxide, zirconium-2,2,6,6-tetramethyl-3,5-heptangeonate, zirconiumtrimethylsiloxide, zirconiumpropionate ,

Examples thereof include hafnium-n-butoxide, hafnium-t-butoxide, hafnium ethoxydo, hafnium-2,4-pentanedionate, hafnium tetramethylheptaneate and the like.

Alkoxide is also a preferable example for the elements other than titanium, zirconium and hafnium mentioned above.

As the precursor containing the element A and the precursor containing the element M, one kind may be used alone, or two or more kinds may be used in any combination and ratio. Further, the precursor may be present in any state in the reaction solution. Usually, the precursor is often present in a dissolved state in an oxygen-containing organic solvent.

In the first step, the precursor containing the element A, the precursor containing the element M, the amines, and the oxygen-containing organic solvent are used in an excess amount of the element A with respect to the composition of the perovskite type crystal phase. It is preferable to mix them in such a manner to obtain a reaction solution. In addition, "the excess amount of the element A with respect to the composition of the perovskite type crystal phase" means that the molar ratio of the element A to the element M is larger than 1. Among them, the molar ratio (A / M) of the element A to the element M in the reaction solution depends on the composition ratio of the target perovskite type crystal, but is preferably 1.05 or more and 10 or less, for example. The lower limit is more preferably 1.2 or more, particularly preferably 1.5 or more, and the upper limit is more preferably 8 or less, particularly preferably 4 or less.

11.2. Oxygen-containing organic solvent The oxygen-containing organic solvent functions as a reaction solvent when synthesizing composite oxide particles from the precursor, and also functions as an oxygen supply source for supplying oxygen to the precursor. As the oxygen-containing organic solvent, any organic solvent containing an oxygen atom in the molecule can be used without any other limitation.

The carbon number of the oxygen-containing organic solvent is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 or more, and usually 30 or less, preferably 20 or less, and more preferably 10 or less.

The molecular weight of the oxygen-containing organic solvent is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 32 or more, preferably 50 or more, more preferably 70 or more, and usually 500 or less, preferably 400 or less, more preferably. Is 300 or less.

The boiling point of the oxygen-containing organic solvent is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 50 ° C. or higher, preferably 70 ° C. or higher, more preferably 100 ° C. or higher, still more preferably 150 ° C. or higher, and usually. It is 300 ° C. or lower, preferably 270 ° C. or lower, and more preferably 250 ° C. or lower.

Oxygen-containing organic solvents are roughly classified into alcohol-based solvents, glycol-based solvents, glycol ether-based solvents, glycol ester-based solvents, ketone-based solvents, aldehyde-based solvents, ether-based solvents, ester-based solvents, siloxane-based solvents, and the like. , The type is not particularly limited. Further, the number of oxygen atoms contained in one molecule of these oxygen-containing organic solvents is not particularly limited as long as it is one or more. Specific examples of the oxygen-containing organic solvent include ethanol, methanol, benzyl alcohol, 2-methoxyethanol, ethylene glycol, diethylene glycol, methylethanolamine, diethanolamine, acetone, benzaldehyde, cyclohexanone, acetophenone, diphenyl ether, hexamethyldisiloxane and the like. However, it is not particularly limited to these. Among these, benzyl alcohol and 2-methoxyethanol are preferable. As the oxygen-containing organic solvent, one type can be used alone, and two or more types can be used in any combination and ratio.

The amount of the oxygen-containing organic solvent used is not particularly limited and can be appropriately set. However, if the concentration of the composite oxide precursor with respect to the solvent is too large, the average crystallite diameter of the obtained composite oxide powder becomes too large. In some cases. Therefore, in order to make the average crystallite diameter of the composite oxide powder 10 nm or less, the concentration of each composite oxide precursor in the oxygen-containing organic solvent should be 0.1 mol / L or more and 1.0 mol / L or less, respectively. It is preferable to use an oxygen-containing organic solvent. It is more preferably 0.3 mol / L or more, still more preferably 0.5 mol / L or more, still more preferably 0.8 mol / L or less, still more preferably 0.6 mol / L or less. It is preferable to adjust the ratio of the precursor containing the element A and the precursor containing the element M so as to be within the above range.

11.3. Amines As the amines, any of primary amines, secondary amines and tertiary amines can be used. However, from the viewpoint of the combined effect of amines and oxidative deterioration coloring, primary amines and / or secondary amines are preferable, and primary amines are more preferable.

Among the amines, aliphatic amines are particularly preferable. This is because it has a high action as a particle stabilizer during synthesis. In particular, primary and / or secondary aliphatic amines are particularly preferable because they have the advantage of being highly effective as a particle growth promoter or inhibitor.

The carbon number of the amines is arbitrary as long as the above problems can be solved, but is usually 8 or more, preferably 14 from the viewpoint of the combined effect as a particle stabilizer during synthesis and the removability of the amine modified at high temperature. As mentioned above, it is more preferably 16 or more, and usually 24 or less, preferably 20 or less, and more preferably 18 or less.

Specific examples of amines include, but are not limited to, oleylamine, octylamine, dioctylamine, aniline, methylethanolamine, diethanolamine and the like. As the amines, one type can be used alone, and two or more types can be used in any combination and ratio.

The amount of amines used is not particularly limited and can be appropriately set. Considering the average crystallinity and crystallinity of the obtained composite oxide particles, the generation of impurities, etc., the molar ratio to the precursor containing the element M is preferably 0.5 times or more, more preferably 1.5 times or more. It is more preferably 2.0 times or more, preferably 10 times or less, more preferably 6 times or less, still more preferably 4 times or less.

1.1.4. Other Additives In addition to the precursors, oxygen-containing organic solvents and amines described above, additives may coexist in the reaction solution. Examples of the additive include carboxylic acids, solvents other than oxygen-containing organic solvents, phosphines and the like, but are not particularly limited thereto.

The carboxylic acids are for modifying the obtained composite oxide particles with the carboxylic acids. By coexisting carboxylic acids in an oxygen-containing organic solvent, composite oxide particles having carboxylic acids on the surface can be obtained. Therefore, it is possible to improve the solubility of the composite oxide particles in an organic solvent depending on the application.

The type of carboxylic acid is not particularly limited. Any carboxylic acid can be used as long as it can be bonded to the composite oxide particles. Aliphatic carboxylic acids are preferable from the viewpoint of suppressing coloration.

The number of carbon atoms of the carboxylic acid is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 8 or more, more preferably, from the viewpoint of the combined effect as a modifier and the removability of the carboxylic acid modified at high temperature. Is 14 or more, more preferably 16 or more, still preferably 24 or less, more preferably 20 or less, still more preferably 18 or less.

Specific examples of the carboxylic acids include, but are not limited to, oleic acid, caprylic acid, behenic acid, stearic acid, myristic acid, palmitic acid and the like. As the carboxylic acids, one type can be used alone, and two or more types can be used in any combination and ratio.

The amount of the carboxylic acid used is not particularly limited and can be appropriately set. Considering the combined effect as a modifier and the quality of the obtained composite oxide particles, the molar ratio to the composite oxide precursor is preferably 0.1 times or more, more preferably 0.75 times or more, still more preferably. Is 1.0 times or more, preferably 5 times or less, more preferably 3 times or less, still more preferably 2 times or less.

When amines and carboxylic acids are used in combination, the ratio of carboxylic acids used is preferably 1/2 times or less, more preferably 1/4 times or less, in terms of the molar ratio with respect to amines.

The reaction solution may contain a solvent other than the oxygen-containing organic solvent. As long as the above-mentioned composite oxide particles can be obtained, there are no restrictions on the types and amounts of other solvents used. Examples of other solvents include water and the like. In addition, one type of other solvent can be used alone, and two or more types can be used in any combination and ratio.

1.1.5. Operation when preparing the reaction solution The specific operation when preparing the reaction solution is arbitrary. In addition, the order in which the above-mentioned precursors, oxygen-containing organic solvents and amines and additives used as necessary are mixed is also arbitrary. In general, many precursors react rapidly with moisture in the air, so it is preferable to mix them in an inert gas such as a nitrogen atmosphere. For example, a method of nitrogen bubbling an oxygen-containing organic solvent for a predetermined time, mixing and stirring a predetermined amount of a precursor, and then mixing a predetermined amount of amines and additives can be mentioned.

1.2. Second step (S2)
In the second step, the reaction solution obtained in the first step is subjected to a solvothermal method to obtain a synthetic solution containing a solid content. The "solvothermal method" means a method for producing particles under the pressure of the solvent at the synthesis temperature of the solvent of the precursor of the element A and the solvent of the precursor of the element M.

The reaction temperature (temperature of the reaction solution) in the solvothermal method is arbitrary as long as the composite oxide particles can be obtained. One of the features of this method is that composite oxide particles can be obtained at a relatively low temperature. From this point of view, the reaction temperature is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and more preferably 240 ° C. or lower, more preferably 200 ° C. or lower. If the reaction temperature is too low, the crystallinity tends to decrease, and if the reaction temperature is too high, the amount of by-products due to the decomposition of organic substances tends to increase, and the quality of the composite oxide particles that can be obtained tends to decrease. The reaction temperature may be set in consideration of the balance of.

The reaction temperature may be constant or fluctuating. Further, the temperature of the reaction solution may be continuously within the above-mentioned reaction temperature range, or may be intermittently contained. Further, the temperature in the reaction solution may be uniform or non-uniform. Therefore, as long as the above-mentioned composite oxide particles can be obtained, for example, a part of the reaction solution may be outside the above-mentioned reaction temperature range.

Further, the pressure conditions in the solvothermal method are also arbitrary as long as the composite oxide particles can be obtained. Normally, the pressure condition is less than or equal to the self-pressure. Here, the self-pressure means the vapor pressure of the oxygen-containing organic solvent at the temperature.

Further, the reaction time in the solvothermal method is also arbitrary as long as the composite oxide particles can be obtained. One of the advantages of this method is that composite oxide particles can be obtained in a shorter time than before by allowing a composite oxide precursor, an oxygen-containing organic solvent and amines to coexist in the reaction system. .. Although the reaction time is not particularly limited, it is preferably 1 minute or longer, more preferably 5 minutes or longer, and particularly preferably 30 minutes or longer in order to make the average crystallite diameter 10 nm or less. .. On the other hand, if the reaction time is too long, the average crystallite diameter of the composite oxide particles may become too large. Therefore, in order to keep the average crystallite diameter to 10 nm or less, the reaction time is preferably 48 hours or less. More preferably, it is 24 hours or less.

Further, the atmosphere at the time of reaction in the solvothermal method is also arbitrary as long as composite oxide particles can be obtained. In general, the reaction is preferably carried out in an inert atmosphere. This is because many of the above precursors react rapidly with moisture in the air. The term "inactive atmosphere" here means that the atmosphere is inert to any of the precursor, the oxygen-containing organic solvent, and the amines. Examples of the atmosphere gas constituting the inert atmosphere include nitrogen, argon, helium and the like. In addition, a single inert gas can be used for the inert atmosphere, and two or more kinds of inert gases can be used in any combination and ratio.

In the solvothermal method, in order to satisfy the above reaction conditions, for example, the reaction solution may be kept at the above-mentioned predetermined reaction temperature in a closed container. For example, the reaction solution may be sealed in a closed container (autoclave container or the like) under an inert atmosphere and heated in the closed container to maintain the reaction temperature at the above-mentioned predetermined reaction temperature.

It is also possible to prepare the reaction solution and proceed with the reaction as a series of steps. For example, if a precursor, an oxygen-containing organic solvent and amines and, if necessary, an additive are mixed in an environment in which predetermined reaction conditions are prepared in advance, the preparation of the reaction solution and the progress of the reaction can be distinguished from each other. It is possible to carry out as a series of steps that do not.

1.3. Third Step In the third step, composite oxide particles are obtained by treating the solid content obtained in the second step with an acid solution of less than 5% by mass. That is, by washing the solid content with an acid solution of less than 5% by mass, impurities containing the element A are removed from the solid content to obtain composite oxide particles. The term "acid solution of less than 5% by mass" means a solution containing an acid component and having an acid component concentration of less than 5% by mass. By performing such a treatment, it is possible to remove only the element A component such as excess Ba in the surface amorphous component. Therefore, in the composition of the entire composite oxide particles finally obtained, the molar ratio (A / M) of the element A to the element M can be 0.85 or more and 1.20 or less, and the perovskite type crystal. Composite oxide particles having an average phase crystallite diameter of 10 nm or less can be obtained. If the acid concentration for treating the solid content is too high, not only the excess element A in the solid content is removed, but also the element A constituting the perovskite-type crystal phase is ionized and removed, which is preferable. The type crystal phase may not be obtained. Therefore, it is important to use less than 5% by weight of acid solution in the third step. Among them, the concentration of the acid component is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, while 2 It is more preferably 5.5% by mass or less, and particularly preferably 1% by mass or less.

The method for treating the solid content with an acid solution of less than 5% by mass is not particularly limited, but an acid solution of less than 5% by mass is added to the solid content to disperse the solid content, and centrifugation is performed. Just do it. As for the solid content after the acid treatment, the precipitate separated by centrifugation may be recovered.

When the solid content is treated with an acid, if the amount of the acid with respect to the solid content is too small, it is insufficient to remove the excess element A, and if it is too large, the excess element A or more is deleted. Therefore, it is preferably 0.05 times or more, more preferably 0.1 times or more, particularly preferably 0.15 times or more, and further preferably 1.25 times or less. It is preferably 0.5 times or less, and particularly preferably 0.5 times or less.

The type of acid is not particularly limited, and examples thereof include phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, citric acid, malic acid, tartaric acid, capric acid, acrylic acid, and methacrylic acid. Of these, an acid that dissolves in a water-soluble organic solvent, reacts with the element A of the composite oxide, and does not cause precipitation is preferable. Further, in the case of a carboxylic acid that can contribute to the dispersion of the composite oxide, since the residual component can contribute as a dispersant for the composite oxide, acrylic acid, methacrylic acid, acetic acid, formic acid, citric acid, malic acid, tartaric acid, or caprylic acid. Is particularly preferable.

The acid solvent is not particularly limited, but when water is used as the solvent, the dissociation of the acid becomes large and it may affect the removal of the element A in the perovskite type crystal phase, so that the solvent is water-soluble. Organic solvent is preferred. Of these, water-soluble alcohols are preferable, and specific examples thereof include methanol, ethanol, isopropanol, benzyl alcohol, and methoxyethanol.

The number of times the solid content is treated with an acid is not particularly limited, and the amount of the solid content obtained in the second step and the molar ratio of the element A and the element M contained in the reaction solution in the first step are not particularly limited. In consideration of (A / M) and the like, each may be performed an appropriate number of times.

In the third step, after obtaining the composite oxide particles, the solvent (for example, a water-soluble alcohol) is removed if necessary. Removal of the solvent can be carried out, for example, by depressurization and / or heating. Using the composite oxide particles from which the solvent has been removed in this way, the dispersion liquid described later can be prepared. Alternatively, it may be used as it is as a dispersion liquid without removing the solvent. For example, the above supernatant liquid can be used as it is as a dispersion liquid.

Further, in order to remove impurities in the synthetic liquid, it is preferable to treat the solid content in the synthetic liquid obtained in the second step with a hydrophilic organic solvent before treating with the acid. Specifically, a hydrophilic organic solvent may be added to the synthetic solution obtained in the second step, mixed and stirred, and then centrifugation may be performed. For the solid content after the treatment, the precipitate obtained by centrifugation may be recovered. Examples of such a hydrophilic organic solvent include methanol, ethanol, n-propanol, and isopropanol. In particular, in the third step, it is preferable to recover the solid content after mixing methanol with the synthetic solution, and treat the recovered solid content with the acid solution. The amount of the hydrophilic organic solvent added to the synthetic solution is not particularly limited, but the mass ratio is preferably 10 times or more, more preferably 25 or more, and on the other hand, 50 or less. Is preferable, and 100 or less is particularly preferable.

Further, in the third step, in order to remove a trace amount of impurities containing element A such as a carbonic acid compound and an aggregated composite oxide remaining after the acid treatment, the solid content is further treated with an acid and then the solid. It is preferable to treat the fraction with a hydrophilic organic solvent. Examples of the hydrophilic organic solvent include alcohols having 2 or more carbon atoms. Specifically, ethanol is preferable. That is, in the third step, it is preferable that the solid content is treated with an acid solution and recovered, and then the recovered solid content is treated with ethanol. Specifically, it is preferable to add a hydrophilic organic solvent to mix and stir the solid content after the acid treatment. Then, the solid content may be recovered again by concentrating and drying the supernatant obtained by centrifugation or the like. The amount of the hydrophilic organic solvent added to the solid content is not particularly limited, but is preferably 10 times or more, more preferably 20 or more, and 100 or less in terms of mass ratio. It is preferably 50 or less, and more preferably 50 or less. By performing such an operation, the molar ratio (A / M) of the element A and the element M can be brought closer to the ideal 1 as a perovskite type crystal.

The number of times of the above operations before and after the solid acid treatment step is not particularly limited. Considering the amount of solid content obtained in the second step, the molar ratio (A / M) of the element A and the element M contained in the reaction solution in the first step, etc., each should be performed an appropriate number of times. good.

As described above, according to the production method S10, the solid content obtained by the predetermined sorbothermal method (S1, S2) is treated with an acid solution of less than 5% by mass, whereby the ratio of the element A to the element M ( A / M) can be brought close to ideal 1 as a perovskite type crystal, and composite oxide particles having an extremely small average crystallite diameter can be obtained.

2. 2. Composite Oxide Powder The composite oxide powder of the present embodiment includes a plurality of composite oxide particles. The composite oxide particles are composed of one or more elements A selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn, and Ti, Zr, W, Nb, Hf, and Sn. It contains one or more elements M selected from the group, and has a perovskite-type crystal phase composed of the element A, the element M, and oxygen. In the composite oxide powder, the molar ratio (A / M) of the element A to the element M is 0.85 or more and 1.20 or less in the composition of the whole powder, and the average crystallite diameter of the perovskite type crystal phase is It is characterized by having a diameter of 10 nm or less.

The element A is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn, and is preferably selected from the group consisting of Ba, Sr, Ca, and Pb1. More than a seed. Preferred elements of the element A and the element B include the same elements as those described in the above-mentioned "1.1.1. Precursor containing element A and precursor containing element M". ..

The composite oxide powder of the present embodiment is characterized in that the molar ratio (A / M) of the element A to the element M is 0.85 or more and 1.20 or less in the composition of the whole powder. The lower limit of the molar ratio (A / M) is preferably 0.90 or more, and the upper limit is preferably 1.10 or less.

In the composite oxide powder of the present embodiment, the molar ratio (A / M) of the element A to the element M is not completely 1 except when the perovskite crystal phase in the composite oxide particles has a lattice defect. , The purpose is to allow the case where the composite oxide particles contain a different phase (including an amorphous phase) other than the perovskite type crystal phase. That is, in the composite oxide powder of the present embodiment, the composite oxide particles do not necessarily have to consist only of the perovskite type crystal phase. However, needless to say, the larger the proportion of the perovskite-type crystal phase in the composite oxide particles, the more preferable.

The composition of the perovskite crystal phase contained in the composite oxide particles of the present embodiment, when expressed by a general formula _{A x B y O 3 ± δ} , x and y are limited in particular as long as they can maintain a perovskite crystal structure is not it. For example, it can be appropriately determined within the range of satisfying 0 <x ≦ 1 and 0 <y ≦ 1. The composite oxide powder of the present embodiment has a feature that the composition of the whole powder is close to the composition of the perovskite type crystal represented by _{ABO 3 in which x / y = 1.} For example, a composite oxide particle containing Ba as the element A and Ti as the element M has a barium titanate (BaTIO ₃ ) phase as a perovskite-type crystal phase and has a molar ratio of Ba and Ti as the composition of the entire powder. It is 0.85 or more and 1.20 or less.

In the present specification, the above general formula _{A x B y O 3 ± δ} , it is a formula for representing the combination of element A and element M and oxygen atoms in the perovskite type crystal phase. Therefore, as long as it contains at least element A, element M, and an oxygen atom, which are essential constituent elements, the composite oxide particles of the present embodiment contain two or more elements M even if they contain two or more elements A. However, it may contain other elements other than these (hereinafter, also simply referred to as "element D"). Further, such elements D have the general formula A _{x B} y _O 3 elements and can have substituted the A site and / or B site of the perovskite-type crystal structure represented by _{± [delta].} A known element can be used as the element D for the purpose of stabilizing the crystal structure, suppressing the transfer of electric charge due to oxygen defects, and the like. For example, examples of the element D1 replacing the A site include La, Bi, Y, Ce, Li, Na, Ag, K, and Fe, and examples of the element D2 replacing the B site include Ta, Mn, and Fe. Examples thereof include Co, Ni and Cu. When the composite oxide particles contain the element D, the content of the element D1 to be replaced with the A site is preferably 0.001 mol% or more and 1 mol% or less, and 0.01 mol% or more and 0.1. More preferably, it is mol% or less. The content of the element D2 to be substituted with the B site is preferably 0.001 mol% or more and 1 mol% or less, and more preferably 0.01 mol% or more and 0.1 mol% or less with respect to the element M.

Preferred examples of the perovskite-type crystal phase represented by the general formula _{A x B} y _O 3 _± δ described above (the representative formula) are shown below. In the following representative composition formula, 0 <x <1 and 0 <y <1.
Barium titanate [BaTIO ₃ ],
Strontium titanate [SrTiO ₃ ],
Barium titanate strontium [(Ba _x Sr _1-x ) TiO ₃ ],
Calcium titanate [CaTIO ₃ ],
Barium zirconate titanate _{[Ba (Ti y Zr 1-} y) O 3],
Lead titanate zirconium acid [Pb (Ti _y Zr _1-y ) O ₃ ],
Zirconate titanate, barium strontium _{[(Ba x Sr 1-x} ) (Ti y Zr 1-y) O 3],
Zirconate titanate, barium calcium _{[(Ba x Ca 1-x} ) (Ti y Zr 1-y) O 3],
Barium zirconate [BaZrO ₃ ],
Strontium zirconate [SrZrO ₃ ],
Barium titanate [BaSnO ₃ ],
Strontium stinate [SrSnO ₃ ] and the like.

The perovskite-type crystal phase of the composite oxide particles can be confirmed from the X-ray diffraction profile obtained by the powder X-ray diffraction measurement. For example, in barium titanate (BaTIO ₃ ) having a perovskite type crystal structure, in powder X-ray diffraction measurement, (100) plane, (110) plane, (111) plane, (200) plane, (210) plane, (211) plane. ) Plane, (220) plane, (300) plane, (310) plane, and the like, an X-ray diffraction pattern can be obtained.

The composite oxide powder of the present embodiment has another feature that the average crystallite diameter is 10 nm or less. The lower limit of the average crystallite diameter is not particularly limited, but is usually 1 nm or more. The average crystallite diameter is more preferably 2 nm or more, further preferably 3 nm or more, still more preferably 8 nm or less, still more preferably 7 nm or less. When the average crystallite diameter is within the above preferable range, for example, the size effect is reduced, the difference in refractive index from the organic component can be made larger, and a high refractive index imparting effect tends to be easily obtained, and Rayleigh scattering is suppressed. It tends to be easy to obtain high transparency. Further, by setting the average crystallite diameter in the composite oxide powder within the above range, the dielectric layer can be thinned. Therefore, even in a laminated capacitor in which a plurality of dielectric layers are laminated, it is possible to achieve miniaturization and large capacity.

The average crystallinity diameter in the composite oxide powder can be obtained from the following Scherrer equation from the half width of the crystalline peak obtained by the powder X-ray diffraction method.
[Scherrer equation] Crystallite size (D) = K · λ / (β · cosθ)

Here, K is a Scherrer constant, K = 0.9, and X-ray (CuKα1) wavelength (λ) = 1.54056 Å (1 Å = 1 × 10 ⁻¹⁰ m). Further, in order to further improve the accuracy, it is preferable to calculate the Bragg angle (θ) and the full width at half maximum (βo) derived from the CuKα1 line by using the profile fitting method (Peason-VII function). It is preferable that the half-value width β used in the calculation is corrected by using the following formula from the half-value width βi derived from the apparatus previously obtained by the standard Si.

The composite oxide powder of the present embodiment preferably has an average dispersed particle size of 50 nm or less. The lower limit is not particularly limited, but is usually 1 nm or more. It is preferably 3 nm or more, more preferably 5 nm or more, and preferably 20 nm or less, more preferably 10 nm or less. The "average dispersed particle size" is a volume-based median size (D50) of dispersed particles measured by a dynamic light scattering type particle size measuring device in a dispersion liquid in which a composite oxide powder is dispersed in a solvent. means. As the dispersion liquid, a 2-methoxyethanol-containing solvent shall be used.

Further, the composite oxide powder of the present embodiment preferably has photocatalytic activity. Titanium oxide is known to have photocatalytic activity. Therefore, when titanium oxide is present on the particle surface of the composite oxide powder, the photocatalytic action can be confirmed.

Further, from the viewpoint of obtaining an optical material having excellent transparency, the composite oxide powder of the present embodiment has a measurement wavelength of 550 nm and an optical path length of 1 cm when dispersed in a solvent with a composite oxide content of 10% by mass. It is preferable to have a transmittance of 50% or more, more preferably 60% or more, still more preferably 65% or more.

Here, the high refractive index material is required to have a higher refractive index, but in order to increase the refractive index by the hybrid material, it is possible to increase the content of the composite oxide having a higher refractive index than the organic material. is necessary. Examples of the hybridization method include a method of directly adding and dispersing the composite oxide powder to the organic material, and a method of dispersing the solvent dispersion liquid in which the composite oxide powder is previously dispersed in the solvent in the organic material. However, the latter method, that is, the method using a solvent dispersion, tends to obtain a highly transparent dispersion. Therefore, in order to obtain a hybrid material having a high refractive index, it is necessary for the solvent dispersion liquid to contain a desired amount of the composite oxide powder in the hybrid material with a small amount of the solvent dispersion liquid when the solvent dispersion liquid contains a large amount of the composite oxide powder. be able to. Further, since the amount of the composite oxide powder in the solvent dispersion is large, the amount of the solvent is relatively small, which is advantageous because the solvent removing step for obtaining the hybrid material can be shortened. Therefore, the content of the composite oxide powder dispersed in the solvent is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 50% by mass or more. On the other hand, the upper limit thereof is not particularly limited, but usually when it is contained in an amount of more than 50% by mass, gelation tends to occur easily in the solvent.

3. 3. Dispersion liquid The dispersion liquid of the present embodiment contains the above-mentioned composite oxide powder and a solvent. The composite oxide powder is as described above, and description thereof will be omitted here.

3.1. The solvent of the solvent dispersion liquid is not particularly limited as long as the above-mentioned composite oxide powder can be dispersed, but an organic solvent is preferably used from the viewpoint of dispersibility of the above-mentioned composite oxide powder and the like. Suitable organic solvents include aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, alcohol solvents, ester solvents, ether solvents, ketone solvents, glycol solvents, glycol ether solvents, and glycol ester solvents. And so on.

Aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as normal hexane, isohexane, cyclohexane, normal heptane, isooctane and normal decane, and alcohol solvents include methanol, ethanol and normal propanol. , Isopropanol, normal butanol, isobutanol, tertiary butanol, secondary butanol, 1,3-butanediol, 1,4,-butanediol, 2-ethyl-1-hexanol, benzyl alcohol, etc., as an ester solvent, acetic acid. Ethyl, methyl acetate, butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, normal propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, butyl lactate, etc. As ether solvents, 1,4-dioxane, isopropyl, etc. Glycol ether solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol, etc. as ether and ketone solvents, and ethylene glycol, diethylene glycol, triethylene glycol, 1,2-dihydroxypropane, etc. as glycol solvents. Examples include 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-tert-butoxyethanol, 2-isobutoxyethanol, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether. , Diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, diethylene glycol monohexyl ether, propylene glycol monomethyl ether propionate, dipropylene glycol methyl Glycol ester-based solvents such as ether include propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate and the like, and other special solvents include tetrahydrofuran, 2-methyl tetrahydrofuran and cyclopentylmethyl. Ether, N-methylpyrrolidone, dimethylsulfoxide, simethylformamide, etc. Can be mentioned. Among these, oxygen-containing organic solvents that can be used when synthesizing composite oxide particles are preferable, and alcohol-based solvents and glycol ether-based solvents are particularly preferable. It should be noted that one of these can be used alone, and two or more of them can be used in any combination and ratio.

The composition of the dispersion is not particularly limited as long as it contains at least the above-mentioned composite oxide powder and solvent. For example, in optical applications, the dispersion liquid contains a precursor (for example, a matrix resin or monomers) for constituting an optical material (molded body), a polymerization initiator, a polymerization accelerator, a polymerization inhibitor, a curing agent, and the like. May be. Further, the dispersion liquid may contain various additives known in the art, for example, a dispersant, an antioxidant and the like. Hereinafter, these optional components will be described in detail.

3.2. Resin / Monomer As the resin / monomer, various known ones can be used, and the type thereof is not particularly limited. When used as an optical material, a resin having transparency in the ultraviolet region to the near infrared region is preferable. For example, a resin obtained by polymerizing or copolymerizing a monomer having a functional group capable of radical polymerization by radiation or heat (hereinafter, also referred to as “polymerizable functional group”) using a polymerization initiator as necessary. , Can be suitably used. Further, from the viewpoint of productivity and the like, a curable monomer that can be polymerized by radiation (hereinafter, also referred to as “radiation-curable monomer”) is polymerized or copolymerized by using a polymerization initiator as necessary. Resin is preferred. The type of the radiation-curable monomer is not particularly limited, but the ultraviolet-curable monomer is preferable from the viewpoint of productivity and the like.

The resin used here may be a resin obtained by polymerizing a monomer having one polymerizable functional group (hereinafter, also referred to as “monofunctional monomer”), and a monomer having two or more polymerizable functional groups (hereinafter, also referred to as “monofunctional monomer”). Hereinafter, any of the resins obtained by polymerizing (hereinafter, also referred to as “polyfunctional monomer”) may be used, but from the viewpoint of easy control of flexibility and the like, two or more types having different numbers of polymerizable functional groups are used. A resin obtained by copolymerizing a monomer is preferable. Preferred resins include at least one selected from acrylic resins, methacrylic resins, epoxy resins, and silicone resins from the viewpoint of transparency, refractive index, productivity, and the like.

One of these resins can be used alone, and two or more of these resins can be used in any combination and ratio. When two or more kinds of resins are used, the kind and ratio of the resins to be combined are arbitrary. From the viewpoint of ease of controlling the flexibility, it is preferable to use at least one of the acrylic resin and the methacrylic resin as the main component. The main component means a component that occupies 50% by mass or more. Specific examples of the combination of resins include a combination of an acrylic resin and a methacrylic resin, at least one of an acrylic resin and a methacrylic resin as a main component, and an epoxy resin, a silicone resin, or an epoxy resin and a silicone resin as subcomponents. Combinations, etc. can be mentioned.

Among these, it is preferable to contain at least one of an acrylic resin and a methacrylic resin, and a resin obtained by copolymerizing at least one of an acrylic resin and a methacrylic resin is most preferable.

As the monomer constituting the resin component, a monomer having an acryloyl group, a methacryloyl group, / or an epoxy group or the like as a functional group capable of radical polymerization by radiation is preferably used.

Hereinafter, the monomers preferably used as the monomers constituting the acrylic resin, the methacrylic resin, the epoxy resin, and the silicone resin, and the polymerization initiator and the curing agent used as necessary are exemplified.

(I) Monomer constituting acrylic resin and / or methacrylic resin and polymerization initiator [monomer]
As the monomer constituting the acrylic resin and the methacrylic resin, a monomer having an acryloyl group and / or a methacryloyl group is preferably used. The monomer having an acryloyl group and / or a methacryloyl group may be monofunctional or polyfunctional, and may be either an aliphatic (including an alicyclic) or an aromatic. In addition, "(meth) acrylate" means one or both of "acrylate" and "methacrylate". The same applies to "(meth) acrylic". Examples of the monofunctional (meth) acrylate-based monomer include monofunctional aliphatic (including alicyclic) (meth) acrylate-based monomers and monofunctional aromatic (meth) acrylate-based monomers. Examples of the polyfunctional (meth) acrylate-based monomer include a bifunctional (meth) acrylate-based monomer and a trifunctional or higher-functional (meth) acrylate-based monomer. Examples of the bifunctional (meth) acrylate-based monomer include a bifunctional aliphatic (including alicyclic) (meth) acrylate-based monomer and a bifunctional aromatic (meth) acrylate-based monomer. Examples of the trifunctional or higher functional (meth) acrylate-based monomer include polyfunctional aliphatic (including alicyclic) (meth) acrylate-based monomers and polyfunctional aromatic (meth) acrylate-based monomers. These monomers may be used alone or in combination of two or more. Specific examples of these monomers include the following.

<Monofunctional aliphatic (including alicyclic) (meth) acrylate-based monomers>
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl ( Meta) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, allyl (meth) acrylate, methallyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, polyethylene glycol monoalkyl ether (meth) acrylate, polypropylene glycol monoalkyl ether (meth) Acrylate, nonyl (meth) acrylate, norbornyl (meth) acrylate, decyl (meth) acrylate, 2-bromophenoxyethyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, n- Stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, adamantyl (meth) acrylate, acrylonitrile, 2-hydroxyethyl (meth) Acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, polytetramethylene glycol mono (meth) acrylate, 2- (meth) acryloyloxyethyl-2 -Hydroxyethyl phthalic acid, glycerin mono (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, terminal hydroxyl group polyester mono (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate , Glycidyl (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, octoxypolyethylene glycol-poly Propylene glycol mono (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, mono (2-methacryloyloxyethyl) acid phosphate, mono (2-acryloyloxyethyl) acid phosphate, allyl (meth) acrylate, 2- ( Acryloyloxyethyl acid phosphate monoester, (meth) acrylic acid, carbitol (meth) acrylate, butoxyethyl (meth) acrylate, monofunctional urethane (meth) acrylate, monofunctional epoxy (meth) acrylate, monofunctional polyester (meth) Meta) acrylate, (meth) acryloyl morpholine, etc.

Among these, linear aliphatic (meth) acrylates, (meth) acrylates having an ethylene glycol chain or a propylene glycol chain, hydroxy acrylates, and phosphate group-containing acrylates are preferably used.

<Monofunctional aromatic (meth) acrylate-based monomer>
Phenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxy2-methylethyl (meth) acrylate, phenoxyethoxyethyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, 2-phenylphenoxy Ethyl (meth) acrylate, 4-phenylphenoxyethyl (meth) acrylate, 3- (2-phenylphenyl) -2-hydroxypropyl (meth) acrylate, ethylene oxide-modified p-cumylphenol (meth) acrylate, 2-bromo Phenoxyethyl (meth) acrylate, 2,4-dibromophenoxyethyl (meth) acrylate, 2,4,6-tribromophenoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl ( Meta) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, benzyl (meth) acrylate, phenolethylene oxide-modified (n = 2) (meth) acrylate, nonylphenolpropylene oxide-modified (n = 2.5) (meth) ) Half (meth) acrylate of phthalic acid derivatives such as acrylate, diphenyl-2- (meth) acryloyloxyethyl phosphate, o-phenylphenol glycidyl ether (meth) acrylate, 2- (meth) acryloyloxy-2-hydroxypropylphthalate. , Fluorene skeleton-containing monofunctional (meth) acrylate, hydroxyethylated o-phenylphenol (meth) acrylate, flufuryl (meth) acrylate, etc.

Among these, phenyl (meth) acrylates, phenoxy acrylates, and fluorene skeleton-containing monofunctional (meth) acrylates are preferably used.

<Bifunctional aliphatic (including alicyclic) (meth) acrylate-based monomer>
Neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, 1, 3-adamantandiol di (meth) acrylate, glycerindi (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxypivalate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, 2 Functional urethane (meth) acrylate, bifunctional epoxy (meth) acrylate, bifunctional polyester (meth) acrylate, polyethylene glycol diacrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol hydroxypivalic acid ester di (meth) acrylate, neopentyl Glycol-modified trimethylolpropane di (meth) acrylate, caprolactone-modified di (meth) acrylate of hydroxypivalate neopentyl glycol ester, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, trimethylolpropandi (meth) acrylate , Trimethylol methanedi (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalate glycerin mono (meth) acrylate, 3- (meth) acryloyloxyglycerin mono (meth) acrylate and the like.

<Bifunctional aromatic (meth) acrylate-based monomer>
EO (epoxy) adduct di (meth) acrylate of bisphenol A, trimethylolpropane (meth) acrylic acid benzoic acid ester, 9,9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] fluorene, fluorene Skeleton-containing bifunctional (meth) acrylate, bisphenol A di (meth) acrylate, ethylene oxide-modified bisphenol A (meth) acrylate, propylene oxide-modified bisphenol A (meth) acrylate, reaction of bisphenol A with glycidyl (meth) acrylate Epoxy (meth) acrylate obtained in the above, epoxy (meth) acrylate obtained by the reaction of ethylene oxide-modified bisphenol A and glycidyl (meth) acrylate, and epoxy obtained by the reaction of propylene oxide-modified bisphenol A and glycidyl (meth) acrylate ( Meta) Acrylate, etc.

<Trifunctional or higher aliphatic (meth) acrylate-based monomer>
Dipentaerythritol monohydroxypenta (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, trimethylolpropane tri ( Meta) acrylate, polyfunctional urethane (meth) acrylate, polyfunctional epoxy (meth) acrylate, polyfunctional polyester (
Meta) Acrylate, Tris [2-((meth) acryloyloxy) ethyl] isocyanurate, Tris [2-((meth) acryloyloxy) propyl] isocyanurate, 2,4,6-tris ((meth) acryloyloxyethoxy) ) -1,3,5-triazine, etc.

<Aromatic (meth) acrylate-based monomer with trifunctionality or higher>
Fluorene skeleton-containing polyfunctional (meth) acrylate, 2,4,6-tris ((meth) acryloyloxypropoxy) -1,3,5-triazine and the like.

Of these (meth) acrylate-based monomers, monofunctional aromatic (meth) acrylate-based monomers are preferable from the viewpoint of improving heat resistance. That is, introducing an aromatic ring into the molecular structure of the resin is effective in improving heat resistance. Among the acrylate-based monomers having an aromatic ring introduced, those having high heat resistance include those having a naphthalene structure, a fluorene structure, a bisphenol A structure and the like.

Among the (meth) acrylate-based monomers, urethane (meth) acrylates such as urethane (meth) acrylate and urethane (meth) acrylate oligomer are effective as components for imparting flexibility to the obtained inorganic organic hybrid material. Is. The monomer having a polar functional group in the (meth) acrylate-based monomer can be used as a surface treatment agent for the composite oxide particles. Examples of such monomers include 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, 2- (meth) acryloyloxyethyl acid phosphate, mono (2-methacryloyloxyethyl) acid phosphate, and mono (2-). Examples thereof include half (meth) acrylates of phthalic acid derivatives such as acryloyloxyethyl) acid phosphate, (meth) acrylic acid, and 2- (meth) acryloyloxy-2-hydroxypropylphthalate.

[Polymerization initiator]
The type of polymerization initiator for polymerizing these monomers is not particularly limited as long as it can carry out various polymerization reactions, but a radical polymerization initiator capable of carrying out a radical polymerization reaction is preferable. For example, a polymerization initiator such as acetophenones, benzophenones, benzoin ethers, hydroxyketones, acylphosphine oxides, diazonium cation onium salt, iodonium cation onium salt, and sulfonium cation onium salt may be used depending on the type of curable monomer. , Can be used as appropriate.

Specifically, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 1-hydroxy-cyclohexylphenylketone, 2,2-dimethoxy-1 , 2-Diphenylethan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpho) Renophenyl) Butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1- [4-methylthio] phenyl] -2-morpholinopropane-1-one, benzoinmethyl Ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, bis (2,4,6-trimethylbenzoyl) phenylphosphinoxide, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol Oligomers, isopropylthioxanthone, methyl o-benzoylbenzoate, [4- (methylphenylthio) phenyl] phenylmethane, 2,4-diethylthioxanthone, 2-chlorothioxanthone, benzophenone, ethylanthraquinone, benzophenone ammonium salt, thioxanthone ammonium salt, Bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphinoxide, 2,4,6-trimethylbenzophenone, 4-methylbenzophenone, 4,4'
-Bisdiethylaminobenzophenone, 1,4-dibenzoylbenzene, 10-butyl-2-chloroacrydone, 2,2'-bis (o-chlorophenyl) -4,5,4', 5'-tetrakis (3,4) , 5-Trimethoxyphenyl) -1,2'-biimidazole, 2,2'-bis (o-chlorophenyl) -4,5,4', 5'-tetraphenyl-1,2'-biimidazole, 2 -Benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyldiphenyl ether, acrylicized benzophenone, dibenzoyl, bis (η5-2,4-cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole) -1-yl) -Phenyl) Titanium, o-methylbenzoylbenzoate, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamylethyl ester, active tertiaryamine, carbazole-phenone-based photopolymerization initiator, aclysine Phenyl photopolymerization initiator, triazine photopolymerization initiator, benzoyl, triallyl sulphonium, hexafluorophosphate salt, phosphorus hexafluoride aromatic sulfonium salt, antimony hexafluoride aromatic sulfonium salt, hexafluoride Antimonic aromatic sulfonium salt, hexafluorinated antimonic aromatic sulfonium salt, triallyl sulfonium, hexafluoroantimon, 4-methylphenyl- [4- (2-methylpropyl) phenyl] -hexafluorophosphate (1) -), 1,2-octanedione, 1- [4- (phenylthio) -2- (o-benzoyloxime)], 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3 -Il] -1- (o-acetyloxime), ethyl-4-dimethylaminobenzoate, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate, (9-oxo9H-xanthen-2-yl) ) Phenyliodonium hexafluorophosphate, bis [4-n-alkyl (C10-13) phenyl] iodonium hexafluorophosphate, bis [4-n-alkyl (C10-13) phenyl] iodonium hexafluoroantimon, triphenylsulfonateri Fluorosulfonate, triphenylsulfonium bicyclo [2,2,1] heptane-1-methanesulphonate, (9-oxo9H-xanthen-2-yl) phenylsulfonium hex Safluorophosphate, p-azidobenzaldehyde, p-azidoacetophenone, p-azidobenzoic acid, p-azidobenzaldehyde-2-sulfonic acid Na salt, p-azidobenzalacetophenone, 4,4'-diazide chalcone, 4, 4'-diazidodiphenyl sulfide, 3,3'-diazidodiphenyl sulfide, 2,6-bis- (4'-azidobenzal) -4-methylcyclohexane, 1,3-bis- (4'-azidobenzal) -propanone , 4,4'-diazidocalcon-2-sulfonic acid Na salt, 4,4'-diazidostilben-2,2'-disulfonic acid Na salt, 1,3'-bis- (4'-azidobenzal)- 2'-Disulfonic acid Na salt-2-propanol, 2,6-bis- (4'-azidobenzal) -2'-sulfonic acid (Na salt) cyclohexanone, 2,6-bis- (4'-azidobenzal) -2 '-Sulphonic acid (Na salt) 4-methyl-cyclohexanone, α-cyano-4,4'-dibenzostilben, 2,5-bis- (4'-azidobenzal sulfonic acid Na salt) cyclopentanone, 3- Sulfonyl azide benzoic acid, 4-sulfonyl azide benzoic acid, cinnamic acid, α-cyanocinnamylideneacetone acid, p-azido-α-cyanocinnamic acid, p-phenylenediacrylic acid, p-phenylenedic acrylic acid diethyl ester , Polyvinyl cinnamate, polyphenoxy-isopropyl cinnamylidene acetate, polyphenoxy-isopropyl α-cyanosine namilidene acetate, naphthoquinone (1,2) diazide (2) -4-sulfonic acid Na salt, naphthoquinone (1,2) Diazide (2) -5-sulfonic acid Na salt, naphthoquinone (1,2) diazide (2) -5-sulfonic acid ester (I), naphthoquinone (1,2) diazide (2) -5-sulfonic acid ester (II) ), Naftquinone (1,2) azide (2) -4-sulfonate, 2,3,4,4'-tetrahydroxybenzophenontri (naphthoquinone diazide sulfonic acid) ester, naphthoquinone-1,2,5- (tri) Hydroxybenzophenone) triester, 1,4-iminoquinone-diazide (4) -2-sulfoamide (I), 1-diazo-2,5-diethoxy-4-p-trimercaptobenzene salt, 5-nitroacenaften, N -Acetylamino-4-nitronaphthalene, organic boron compounds, other photoacids that generate cations by light Examples thereof include, but are not limited to, agents, photobase generators that generate anions by light, and the like. These may be used alone or in combination of two or more, depending on the properties of the desired cured product.

(Ii) Monomer constituting epoxy resin and polymerization initiator [monomer]
As the monomer constituting the epoxy resin, a compound having an epoxy group (hereinafter, also referred to as “epoxy monomer”) is preferably used. For example, bisphenol A type epoxy monomer, bisphenol F type epoxy monomer, phenol novolac type epoxy monomer, novolak type epoxy monomer such as cresol novolac type epoxy monomer, alicyclic epoxy monomer, triglycidyl isocyanurate, hydantin epoxy monomer and the like containing nitrogen. Ring epoxy monomer, hydrogenated bisphenol A type epoxy monomer, hydrogenated bisphenol F type epoxy monomer, aliphatic epoxy monomer, glycidyl ether type epoxy monomer, bisphenol S type epoxy monomer, biphenyl type epoxy monomer, dicyclo ring type epoxy monomer, naphthalene Examples include type epoxy monomers. These can be used individually by 1 type or in combination of 2 or more types.

Although only the epoxy monomer may be used as the monomer, or the epoxy monomer may be used in combination with another type of monomer having a polymerizable functional group, other types having a polymerizable functional group with the epoxy monomer may be used in combination. It is preferable to use it in combination with the monomer of. When only the epoxy monomer is used, it is preferable to use a monofunctional monomer and a polyfunctional monomer in combination as the epoxy monomer. When used in combination with an epoxy monomer and another type of monomer that can be polymerized, only one of a monofunctional monomer and a polyfunctional monomer may be used as the epoxy monomer.

In the present specification, the monomer having both a (meth) acryloyl group and an epoxy group is referred to as a (meth) acrylate-based monomer for convenience.

[Curing agent]
As the curing agent for the epoxy monomer, a known curing agent such as an amine-based curing agent or an acid anhydride-based curing agent can be used. Examples of the acid anhydride-based curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnasic anhydride, nagic acid anhydride, and glutanium anhydride. Acids and the like can be mentioned. The curing agent may be used alone or in combination of two or more, depending on the characteristics of the desired cured product.

(Iii) Monomer constituting silicone resin and polymerization initiator [monomer]
As the monomer constituting the silicone resin, a polymerizable silicone monomer is preferably used. For example, a silicone monomer having a functional group capable of polycondensation, hydrosilylation, etc. in the monomer, a radiation-curable silicone monomer, and the like can be mentioned. Specifically, dimethyl silicone, methylphenyl silicone, amino group-containing silicone, carboxy group-containing silicone, carbinol group-containing silicone, phenyl group-containing silicone, organohydrogen silicone, polycyclic hydrocarbon-containing silicone, aromatic ring hydrocarbons. Examples thereof include silicone contained in silicone, silicone monomers such as phenylsilsesquioxane, and the like. These can be used individually by 1 type or in combination of 2 or more types. Among these, a radiation-curable silicone monomer is preferable.

Although only the polymerizable silicone monomer may be used or another type of monomer that can be polymerized with the polymerizable silicone monomer may be used in combination, it is preferable to use the polymerizable silicone monomer in combination with another type of monomer that can be polymerized.

When only the polymerizable silicone monomer is used, it is preferable to use a monofunctional polymerizable silicone monomer and a polyfunctional polymerizable silicone monomer in combination. When the polymerizable silicone monomer and another type of monomer that can be polymerized are used in combination, only one of the monofunctional polymerizable silicone monomer and the polyfunctional polymerizable silicone monomer may be used. In the present specification, the silicone having a (meth) acryloyl group is referred to as a polymerizable silicone monomer for convenience.

[Polymerization initiator]
Depending on the type of monomer, a polycondensation reaction catalyst, a hydrosilylation reaction catalyst, a radiation curing polymerization initiator and the like can be used. As the polycondensation reaction catalyst, a known catalyst can be used. Examples of the hydrosilylation reaction catalyst include aluminum compounds, platinum compounds, rhodium compounds, palladium compounds and the like. Examples of the radiation curing polymerization initiator include a polymerization initiator used for polymerizing the (meth) acrylate-based monomer. These can be used individually by 1 type or in combination of 2 or more types.

In addition to the above-mentioned monomers, a radiation-curable monomer having a functional group such as a vinyl group or an acrylamide group may be contained.

3.3. Dispersant The dispersion may contain a dispersant for dispersing the composite oxide powder or the like, if necessary. The dispersion may contain one or more known dispersants as long as the effects of the present invention are not significantly impaired. As the dispersant used here, from the viewpoint of enhancing the dispersibility of the composite oxide powder, the adsorption site for adsorbing to the composite oxide powder (force ruvoxil group, phosphorus-containing oxoacid group, sulfur-containing oxoacid group, etc.) It is preferable to have. Further, from the viewpoint of not lowering the refractive index and transparency, it is preferable that the dispersant itself has a high refractive index and is transparent. Examples of such a dispersant include dispersants having a polymerizable functional group (polymerizable group) and an adsorption site (adsorbable group). For example, the polymerizable inorganic particle dispersant described in WO2013 / 047786 and the like is preferably used. All content described in WO2013 / 047786 is cited herein by reference.

3.4. Antioxidant The dispersion may contain a known antioxidant such as nitrogen-based or phosphorus-based from the viewpoint of imparting weather resistance and the like. In that case, the content of the antioxidant in the dispersion is preferably 0.01% by mass or more, more preferably 1% by mass or more, and preferably 5% by mass or less with respect to the composite oxide powder. It is more preferably 4% by mass or less, still more preferably 3% by mass or less. When the content of the antioxidant in the dispersion is within the above preferable numerical range, coloring and deterioration tend to be suppressed for a long period of time, and transparency and a decrease in the refractive index tend to be suppressed. be.

3.5. The polymerization inhibitor The dispersion liquid may contain a polymerization inhibitor from the viewpoint of preventing the polymerization of the composite oxide powder. In that case, the content of the polymerization inhibitor in the dispersion is preferably 0.01% by mass or more, more preferably 1% by mass or more, and preferably 5% by mass or less with respect to the composite oxide powder. It is more preferably 4% by mass or less, still more preferably 3% by mass or less. When the content of the polymerization inhibitor in the dispersion is within the above preferable numerical range, gelation in the dispersant tends to be easily prevented for a long period of time, and deterioration of transparency and refractive index is also suppressed. It tends to be easy to do.

3.6. The dispersion liquid may further contain a viscosity adjusting agent, a repelling agent, and the like from the viewpoint of improving the viscosity and handleability. In this case, those having excellent compatibility with the composite oxide powder are preferably used.

3.7. Various Aspects of the Dispersion Liquid The dispersion liquid of the present embodiment is not limited in its mode as long as the above-mentioned composite oxide powder is dispersed in a solvent. Specific embodiments include a dispersant containing the above-mentioned composite oxide powder in a solvent, a dispersant containing the above-mentioned composite oxide powder and a resin / monomer in a solvent, and the above-mentioned composite oxide powder and a resin /. Examples thereof include a dispersant containing a monomer and an optional component such as a polymerization initiator in a solvent, but the present invention is not particularly limited thereto.

3.8. Physical Properties of the Dispersion Liquid The dispersion liquid of the present embodiment preferably has a transmittance of 50% or more at a measurement wavelength of 550 nm and an optical path length of 1 cm from the viewpoint of obtaining an optical material having excellent transparency. Is 60% or more, more preferably 65% or more. Here, in the present specification, the transmittance is a value when a dispersion prepared in which the solid content concentration of the composite oxide powder is 10% by mass or more is used.

3.9. Method for Producing Dispersion Liquid The dispersion liquid of the present embodiment can be easily obtained by mixing the above-mentioned composite oxide powder and the solvent with the above-mentioned optional components, if necessary. Since the composite oxide powder of the present embodiment has high dispersion performance, it is easy to prepare a transparent dispersion liquid in which the composite oxide powder is uniformly dispersed. By adding the above-mentioned dispersant as needed, a more uniform dispersed state can be obtained. Here, after mixing, a dispersion step such as ultrasonic dispersion may be performed as necessary to more uniformly disperse the composite oxide powder. As a method of mixing the dispersant, the composite oxide powder and the dispersant may be mixed in advance and then added to the solvent, or the dispersant may be added to the mixed solution of the composite oxide powder and the solvent.

The content ratio of the composite oxide powder in the dispersion is not particularly limited, but the solid content concentration of the composite oxide powder is preferably 0.1% by mass or more and 90% by mass or less, more preferably 0.1% by mass or more. It is 50% by mass or less. By setting the solid content concentration of the composite oxide powder within the above-mentioned preferable numerical range, it tends to be easy to obtain a dispersion liquid having a high refractive index imparting effect, high dispersion stability of the composite oxide powder, and excellent transparency. ..

4. Hybrid composite particles The hybrid composite particles of the present embodiment contain at least the above-mentioned composite oxide powder and the above-mentioned dispersant adhering to the surface of the particles. By surface-modifying the surface of the particles of the fine composite oxide powder with a dispersant in this way, a composite oxide powder having high dispersibility can be obtained. The hybrid composite particles can be easily obtained, for example, by removing the solvent from the dispersion liquid containing the composite oxide powder and the dispersant in the solvent. It can also be easily obtained by spraying a liquid containing a dispersant onto the composite oxide powder and drying the solvent.

5. Hybrid composite material The hybrid composite material of the present embodiment contains at least the above-mentioned composite oxide powder and a matrix resin or a precursor (monomer) of the matrix resin. As the matrix resin and its precursor used here, the resins / monomers described in the section of the dispersion liquid can be preferably used. Further, the hybrid composite material may contain the optional components described in the section of the dispersion liquid. The above-mentioned composite oxide powder can be mixed with the matrix resin or a precursor thereof, and by mixing the composite oxide powder in this way, the refractive index of the resin or the precursor can be easily increased.

The content ratio of the matrix resin and its precursor in the hybrid composite material is not particularly limited, but from the viewpoint of enhancing the effect of improving the refractive index and enhancing the mechanical properties of the obtained hybrid composite material, etc., with respect to the composite oxide particles. In terms of solid content, it is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and preferably 80% by mass or less.

The method for producing the hybrid composite material described above is not particularly limited. For example, the composite oxide powder can be easily obtained by adding the above-mentioned optional components to the matrix resin and its precursor, if necessary, and mixing them. Since the composite oxide powder of the present embodiment has high dispersion performance, it is possible to easily obtain a hybrid composite material. Further, after mixing, if necessary, a kneading step may be performed to more uniformly disperse the composite oxide powder. Further, by adding the above-mentioned dispersant as needed, a more uniform dispersed state can be obtained.

A wet method is mentioned as a preferable manufacturing method of the hybrid composite material. The wet method referred to here is, for example, a dispersion liquid in which a composite oxide powder and a matrix resin or a precursor thereof are dispersed in a solvent by the above-mentioned method, a desired matrix resin is mixed, and finally the solvent is removed. It's a way to do it. According to such a wet method, the matrix resin or its precursor can be uniformly acted on the particle surface of the composite oxide powder, so that for example, aggregation of the nano-sized composite oxide powder is suppressed and the composite oxide powder is transparent. It is also possible to stabilize the dispersed state.

The hybrid composite material described above can be molded into any shape. In order to obtain a cured product of a hybrid composite material having a predetermined shape, for example, the above-mentioned polymerization initiator or curing agent can be used. At this time, the content of the polymerization initiator is not particularly limited, but is solid with respect to the solid content other than the composite oxide powder in the hybrid composite material from the viewpoint of refractive index, mechanical strength, curability, compatibility, color suppression and the like. In terms of minutes, 0.01% by mass or more is preferable, 0.1% by mass or more, further preferably 1% by mass or more, and 20% by mass or less is preferable, and 10% by mass or less is more preferable. More preferably, it is 5% by mass or less.

Various known molding methods can be applied to the molding of the hybrid composite material. For example, when molding and curing into a film or sheet, the film is formed by a known film forming method such as spin coating, bar coating, spray coating, roll coating, and then irradiated with ultraviolet rays, heat, electron beams, or the like. Can be polymerized and cured. Further, it may be polymerized by ultraviolet rays or the like after pouring it directly into a desired portion using a dispenser or the like. The curing method is not particularly limited, but curing by irradiation with ultraviolet rays (UV) is preferable. In the case of UV irradiation, high-pressure mercury lamps, metal halide lamps, xenon lamps, UV-LEDs, etc. are used as ultraviolet lamps, and the illuminance of ultraviolet rays is from the viewpoints of refractive index, mechanical strength, curability, compatibility, color suppression, etc. , 30~3000mW / cm ^2, accumulated light quantity is preferably cured by irradiation with 10 to 10000 mJ / cm ^2. At this time, these light irradiation or electron beam irradiation may be used in combination with infrared irradiation, hot air application, high frequency heating, or the like.

6. Use of Composite Oxide Powder The composite oxide powder of the present embodiment not only has a high refractive index but also is easily dispersed. Therefore, in the dispersion liquid, the hybrid composite particle, the hybrid composite material, and the optical material using the same, the composite oxide particles having a high refractive index can be easily contained in a large amount, and the content of the composite oxide powder can be increased. It is also possible to change it. Therefore, the composite oxide powder of the present embodiment has a wide range of applications such as optical members used in the visible light region, lens applications for designing one optical system by combining various optical characteristics, optical circuits, optical paths, and the like. It can be suitably used in various applications where flexible refractive index control is required. In particular, the composite oxide powder of the present embodiment is one of the most suitable materials as various optical members that are highly transparent in a wide wavelength range and require a high refractive index. That is, forward scattering, reflection, light collection, etc. used in the display unit of a flat panel display (FPD) such as a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (EL), and a surface electric field display (SED). Ideal for functional films. It can also be applied to optical transmission members such as optical fibers, light guide sheets, microarray lens sheets, prism sheets, Fresnel lenses and lenticular lenses, lens sheets, diffusion films, holographic substrates, dimming films and the like.

Further, since the composite oxide powder of the present embodiment has a high dielectric constant, it is suitable as a dielectric for a capacitor, for example. Specific embodiments of the dielectric for a capacitor are known to those skilled in the art (for example, Japanese Patent Application Laid-Open No. 2017-50346). That is, the composite oxide powder of the present embodiment can be applied to, for example, the dielectric layer of a laminated ceramic capacitor.

Hereinafter, the present invention will be specifically described with reference to examples and the like. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the present invention is not limited to the following examples.

1. 1. Production of Composite Oxide Particles (Composite Oxide Powder) and Dispersion Liquid (Example 1)
First step: Add 288.4 g (0.91 mol) of barium hydroxide octahydrate (precursor containing element A) and 1253 ml of 2-methoxyethanol (oxygen-containing organic solvent) to a nitrogen-substituted flask and stir for 10 minutes. bottom. Next, a solution prepared by dissolving 1251 ml of benzyl alcohol (oxygen-containing organic solvent) and 166.5 g (0.59 mol) of titanium isopropoxide (precursor containing element M) was added, and the mixture was stirred for 10 minutes. Then, 157 g (0.59 mol) of oleylamine (amines) was added and stirred for 10 minutes to obtain a reaction solution.

Second step: The obtained reaction solution was transferred to an autoclave and heated to 160 ° C. over 105 minutes from room temperature to obtain a milky white slurry-like synthetic solution containing a solid content.

Third step: Methanol in an amount (mass ratio) 2.2 times that of the synthetic solution was added to the obtained milky white slurry-like synthetic solution, and the mixture was mixed and stirred. The liquid mixed with methanol was centrifuged to obtain a solid content (1) as a precipitate. To the obtained solid content (1), methanol in an amount (mass ratio) 2.2 times that of the above synthetic solution was added again, dispersed, and then centrifuged to obtain the solid content (2) as a precipitate. Obtained. A methanol solution (acid solution) containing 0.3% by mass of acrylic acid is added to the solid content (2) to disperse the solid content (2), and then centrifugation is performed to contain barium titanate. The solid content (3) was obtained. Next, ethanol is added to the solid content (3) so that the concentration of the solid content (3) containing barium titanate is 5% by mass, dispersion washing is performed, centrifugation is performed, and the precipitate is removed. bottom. The obtained supernatant was concentrated and dried at 70 ° C. to obtain the composite oxide powder of Example 1 (barium titanate powder having a perovskite-type crystal structure).
After adjusting the supernatant, 2-methoxyethanol is added to the adjusted supernatant so that the solid content concentration of the barium titanate powder is 5% by mass, and the dispersion (10% by mass of 2-methoxyethanol) is added. An ethanol dispersion containing%) was prepared, and the average dispersed particle size was measured.

(Comparative Example 1)
First step: 3.45 g (10.94 mmol) of barium hydroxide octahydrate (precursor containing element A) is placed in a flask with 15 ml of 2-methoxyethanol (oxygen-containing organic solvent) and nitrogen bubbling. Was added and stirred for 10 minutes to dissolve. Separately, a solution prepared by dissolving 1.995 g (7.0 mmol) of titanium isopropoxide (precursor containing element M) in 15 ml of benzyl alcohol (oxygen-containing organic solvent) was prepared, and 2-methoxy of barium hydroxide was prepared. It was added to an ethanol solution and stirred for 1 hour. Then, 25 g of oleylamine (amines: 94 mmol) was added and stirred for 2 hours to obtain a reaction solution.

Second step: The obtained reaction solution is sealed in a stainless steel airtight container having an inner cylinder made of Teflon (registered trademark) and heated from room temperature to 160 ° C. over 105 minutes to form a milky white slurry containing 1 solid content. A synthetic solution was obtained.

Third step: 55 g of methanol was added to 25 g of the obtained milky white slurry-like synthetic solution, and the mixture was stirred for 30 minutes. The resulting precipitate was centrifuged to give a solid content (11). Further, 55 g of methanol was added to the obtained solid content (11) to disperse the solid content (11), and then centrifugation was further performed to obtain the solid content (12). 55 g of a 5% by mass acetic acid solution (solvent: acetone / water = 1/1 (mass ratio)) was added to the solid content (12) for dispersion washing, and then centrifugation was performed to obtain a solid content (13). .. Then, 27.5 g of acetone was added to the solid content (13) to disperse the solid content (13), and the operation of centrifugation was repeated twice. The solid content (14) obtained by centrifugation was dried at 120 ° C. for 2 hours to obtain a composite oxide powder of Comparative Example 1 (barium titanate powder having a perovskite-type crystal structure).
Further, 2-methoxyethanol was added to the solid content (14) obtained by centrifugation so that the solid content concentration of barium titanate was 10% by mass to prepare a dispersion, and the average dispersed particle size was measured. ..

(Comparative Example 2)
First step: Add 162.3 g (514 mmol) of barium hydroxide octahydrate (precursor containing element A) and 705.1 ml of 2-methoxyethanol (oxygen-containing organic solvent) to a nitrogen-substituted flask and stir for 10 minutes. bottom. Next, a solution prepared by dissolving 704.3 ml of benzyl alcohol (oxygen-containing organic solvent) and 93.4 g (329 mmol) of titanium isopropoxide (precursor containing element M) was added, and the mixture was stirred for 10 minutes. Then, 1179 g (4407 mmol) of oleylamine (amines) was added and stirred for 10 minutes to obtain a reaction solution.

Second step: The obtained reaction solution was transferred to an autoclave, heated to 160 ° C. for 105 minutes from room temperature and held for 5 hours to obtain a milky white slurry-like synthetic solution containing a solid content.

Third step: To the obtained milky white slurry-like synthetic solution, 2.2 times (mass ratio) of methanol was added to the reaction-terminated solution, and the mixture was mixed and stirred. The solution mixed with methanol was centrifuged, and 2.2 times (mass ratio) of methanol was further added to the obtained solid content (21) to disperse the solution, followed by further centrifugation. The solid content (22) was obtained. A 5% by mass acrylic acid solution (solvent: acetone / water = 1/1 (mass ratio)) was added to this solid content (22) in an amount 2.2 times (mass ratio) of the synthetic solution, and then dispersed and washed. Centrifugation was performed to obtain a solid content (23). Then, the same amount of acetone as the reaction termination liquid was added to the solid content (23) to disperse the solid content (23), and the operation of centrifugation was repeated twice. The solid content (24) obtained by centrifugation was dried at 65 ° C. for 2 hours to obtain a composite oxide powder of Comparative Example 2 (barium titanate powder having a perovskite-type crystal structure).
Further, 2-methoxyethanol was added to the solid content (24) obtained by centrifugation so that the solid content concentration of barium titanate was 10% by mass to prepare a dispersion, and the average dispersed particle size was measured. ..

2. 2. Evaluation of Composite Oxide Powder Elemental analysis and average crystallite diameter of the obtained composite oxide powder were performed by ICP. Each measurement condition and evaluation method are as follows.

2.1. Elemental analysis by ICP An aqueous solution of an acid containing hydrofluoric acid is added to the composite oxide powder to dissolve it, and after dilution, an inductively coupled plasma emission spectrometer (ICP-AES, Thermo Fisher Scientific, CAP7600 Du 0) is used. The measurement was performed. From the obtained elemental analysis results, the molar ratio of Ba and Ti was calculated. In Example 1, since the composite oxide powder was difficult to dissolve in the above aqueous solution, a dry ashing treatment was performed before adding the aqueous acid solution to prepare a solution.

2.2. Average crystallinity diameter The average crystallinity diameter of the composite oxide powder was calculated from the half-value width of the crystalline peak obtained by powder X-ray diffraction measurement (XRD measurement) from the above-mentioned Scherrer equation. The specifications and measurement conditions of the powder X-ray diffraction measurement device are as shown in Tables 1 and 2 below.

<Average dispersed particle size D50>
The average dispersed particle size of the obtained dispersion was measured using a dynamic light scattering type particle size distribution measuring device (SZ-100, manufactured by Horiba, Ltd.).
Holder temperature: 25 ° C
Sample refractive index: 2.40 (barium titanate)

The evaluation results are shown in Table 3 below. In addition, FIGS. 2 to 6 show the powder X-ray diffraction measurement results for each composite oxide powder.

As is clear from the results shown in Table 3, in Example 1, a solid content was obtained by a predetermined sorbothermal method and then treated with an acid solution of less than 5% by mass based on the solid content. The molar ratio (A / M) of the element A to the element M in the finally obtained composite oxide powder could be brought closer to 1 which is ideal for a perovskite type crystal. It is considered that the reason for this is that impurities containing the element A (for example, BaCO ₃ ) could be appropriately removed from the solid content by washing with an acid solution of less than 5% by mass. Further, as is clear from the results shown in FIG. 2, in Example 1, the perovskite-type crystal phase was contained in the composite oxide powder. The average crystallite diameter of the perovskite-type crystal phase was extremely small, 10 nm or less.
On the other hand, in Comparative Examples 1 and 2 in which a solid content was obtained by a predetermined sorbothermal method and then pickled with an acid solution of 5% by mass based on the solid content, the finally obtained composite oxide particles were obtained. The molar ratio (A / M) of the element A and the element M in the above was well below 1, which is ideal for a perovskite-type crystal. It is considered that the reason for this is that the acid component concentration of the acid solution was too high, so that not only impurities containing the element A but also the element A constituting the perovskite type crystal phase were eluted from the solid content by pickling. As is clear from the results shown in FIGS. 3 and 4, the composite oxide powder also contained the perovskite-type crystal phase in Comparative Examples 1 and 2. The average crystallite diameter of the perovskite-type crystal phase was extremely small, 10 nm or less.

Even if the ratio (A / M) of the element A to the element M is set to 1 at the stage of charging the reaction solution, the molar ratio (A / M) of the finally obtained composite oxide particles is much lower than 1. .. That is, since element M is more reactive than element A, a large amount of oxide (titanium oxide, etc.) derived from element M is generated in the composite oxide particles in addition to the target perovskite-type crystal phase. The element A falls off due to the subsequent cleaning operation or the like, and as a result, the ratio of the element M becomes higher than that of the element A. As described above, it is extremely difficult to bring the molar ratio (A / M) in the finally obtained particles close to the ideal 1 by the initial preparation of the element A and the element M.

In the above embodiment, the composite oxide particles using Ba as the element A and Ti as the element M are shown, but the technique of the present disclosure can be used when an element other than Ba is used as the element A or as the element M. Even when an element other than Ti is used, it is considered that the same effect is exhibited from the viewpoint of reactivity. For example, the element A is one or more selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn, and the element B is Ti, Zr, W, Nb, Hf, and Sn. It is considered that the same effect is exhibited when one or more kinds selected from the group are adopted.

Claims (7)

Selected from the group consisting of one or more elements A selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn, and the group consisting of Ti, Zr, W, Nb, Hf, and Sn. A method for producing a composite oxide particle containing one or more elements M and having a perovskite-type crystal phase composed of the element A, the element M, and oxygen.
At least, the precursor containing the element A and the precursor containing the element M are mixed so that the amount of the element A is excessive with respect to the composition of the perovskite type crystal phase to obtain a reaction solution. Process and
The second step of obtaining a synthetic liquid containing a solid content by subjecting the reaction solution to a solvothermal method, and the third step of treating the solid content with an acid solution of less than 5% by mass to obtain composite oxide particles. A method for producing composite oxide particles, comprising a step.
In the third step, the amount of the acid with respect to the solid content is set to 0.05 times or more and 1.25 times or less.
In the composition of the entire composite oxide particles, Ri molar ratio (A / M) is 0.85 to 1.10 der less between the element A and the element M,
The average crystallite diameter of the perovskite-type crystal phase in the composite oxide particles is 7 nm or less.
A method for producing composite oxide particles. The method for producing composite oxide particles according to claim 1, wherein in the third step, the solid content is recovered after mixing methanol with the synthetic solution, and the recovered solid content is treated with the acid solution. The method for producing composite oxide particles according to claim 1 or 2, wherein in the third step, the solid content is treated with the acid solution and recovered, and then the recovered solid content is treated with ethanol. A composite oxide powder having a plurality of composite oxide particles.
The composite oxide particles include one or more elements A selected from the group consisting of Ba, Sr, Ca, Mg, Al, Pb, Co, and Zn, and Ti, Zr, W, Nb, Hf, and Sn. It contains one or more elements M selected from the group consisting of, and has a perovskite-type crystal phase composed of the element A, the element M, and oxygen.
In the composition of the entire composite oxide powder, the molar ratio (A / M) of the element A and the element M is 0.85 or more and 1.10 or less.
The average crystallite diameter of the perovskite-type crystal phase in the composite oxide powder is 7 nm or less.
Composite oxide powder. The average dispersed particle size is 50 nm or less.
The composite oxide powder according to claim 4. A dispersion liquid containing the composite oxide powder according to claim 4 or 5 and a solvent. A dielectric for a capacitor, which comprises the composite oxide powder according to claim 4 or 5.

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