JP2008115060A - Method for producing water dispersion containing chain silica-based fine particle group, water dispersion of chain silica-based fine particle group, and organic solvent dispersion thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a water dispersion containing a chain silica-based fine particle group coated with a metal multiple oxide, and to provide the water dispersion containing the chain silica-based fine particle group and an organic solvent dispersion of the chain silica-based fine particle group. <P>SOLUTION: In the producing method, the water dispersion containing a chain silica-based fine particle group, in which a plurality of silica-based fine particles each covered with a multiple oxide comprising at least zirconium, silicon and oxygen are linked through a coating substance of the silica-based fine particles or a belt-like substance of the multiple oxide extending from the coating substance, is produced. The water dispersion containing the chain silica-based fine particle group and the organic solvent dispersion obtained by solvent substitution are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for producing an aqueous dispersion containing chain silica-based fine particle groups coated with a metal composite oxide, an aqueous dispersion containing the silica-based fine particle group, and an organic solvent dispersion thereof.

  In general, dental fillers need to have sufficient strength and hardness comparable to actual natural teeth, as well as resistance to wear due to surface smoothness and meshing, so silica-based fine particles are used as the raw material. ing. In addition, this dental filler has a color compatibility with natural teeth, a refractive index compatibility to give the same transparency as natural teeth, and a degree that can distinguish between treated sites and natural tooth tissue. Therefore, zirconium oxide is used as another raw material.

  Such dental fillers are disclosed in various known documents. For example, (1) agglomeration of silicon dioxide and at least other metal oxides (zirconium oxide, etc.), and the crystallization temperature of the oxides Dental filler (Patent Document 1) produced by heat treatment at a temperature lower than that and formed by forming an independent amorphous layer of silicon dioxide and other metal oxides, and (2) an average of less than about 100 nm Dental comprising substantially amorphous clusters comprising non-heavy metal oxide particles having a diameter (such as silica particles) and heavy metal oxides or heavy metal oxide particles having an average diameter of less than about 100 nm (such as zirconium oxide particles). Filler (Patent Document 2).

However, the dental filler obtained from these methods is mixed with silica sol and zirconium salt aqueous solution, dried using a spray drier, etc., and then fired, so the properties such as refractive index are different. Silica fine particles and zirconium oxide components (fine particles) were mixed. As a result, unevenness may occur in the refractive index of the obtained dental filler. Furthermore, with these dental fillers, the pore volume of the particles and the strength of the particles cannot be adjusted, which makes it difficult to improve the transparency, and furthermore, the adhesion to the polymerizable resin is reduced. Since it is insufficient, the strength and hardness of the treated or repaired teeth (including dentures) at the treatment site may be reduced, and resistance to wear due to meshing may be insufficient.

  Therefore, the present applicant has developed a method for producing a dental filler (Patent Document 3) in which silica sol, acidic silicic acid solution and zirconium salt aqueous solution are mixed, dried using a spray dryer, and then fired. Have filed this. According to this, since a metal oxide in which a silica component derived from an acidic silicic acid solution and an acidic zirconium component are well mixed is obtained, it becomes a property close to silica fine particles derived from silica sol (for example, refractive index). ing. However, since the silica fine particles are mixed, the above-mentioned problems have not been completely solved.

Furthermore, the present inventors have developed a dental filler containing crystalline inorganic oxide fine particles made of a zirconium silicate compound in order to solve the above-mentioned problems associated with conventional dental fillers. Has been filed as an invention described in Patent Document 4. This dental filler has excellent properties such as strength and hardness comparable to natural teeth, durability against biting wear, etc., but depending on its usage, organosilicon compounds, organic titanium compounds, It is necessary to treat (or modify) the surface of the inorganic oxide fine particles with an organometallic compound such as an organozirconium compound. However, since the inorganic oxide fine particles have a crystalline surface property, it has not always been easy to uniformly treat the surface with the organometallic compound.

The inventors of the present invention have made extensive studies for the purpose of solving these problems, and found that amorphous inorganic oxide fine particles formed by coating the surface of silica-based fine particles with a metal composite oxide are used for dental filling. It was found that it has excellent characteristics as a material, and a patent application was filed on the same date as this application. However, in order to complete this invention, it has been necessary to develop a method for stably producing an aqueous dispersion containing the inorganic oxide fine particles, that is, silica-based fine particles coated with a metal composite oxide. .

JP-A-7-196428 Japanese translation of PCT publication No. 2003-512406 (International publication WO01 / 030306) JP 2003-146822 A Japanese Patent Application No. 2006-086800

Under the circumstances as described above, the inventors of the present application have conducted extensive research on a method for stably producing an aqueous dispersion containing the inorganic oxide fine particles, and have found a novel method shown below. The present invention has been completed. That is, the present invention relates to a method for producing an aqueous dispersion containing a chain silica fine particle group coated with a metal composite oxide, an aqueous dispersion containing the chain silica fine particle group, and the dispersion. An object of the present invention is to provide an organic solvent dispersion containing the group of chain silica fine particles obtained by solvent substitution.

The method for producing an aqueous dispersion containing the chain silica-based fine particle group according to the present invention,
A method for producing an aqueous dispersion containing a group of chain silica-based fine particles formed by coating the surface of silica-based fine particles with a composite oxide comprising at least zirconium, silicon and oxygen,
(A) By adding an alkali metal hydroxide and hydrogen peroxide to an aqueous solution containing zirconium oxide hydrate and stirring, an aqueous solution in which the zirconium oxide hydrate is peptized and dissolved is prepared. Process,
(B) a step of adding the aqueous solution obtained in the step (a) and an aqueous solution of a silicic acid solution with stirring to a silica sol in which silica-based fine particles having an average particle size of 2 to 300 nm are dispersed in water;
(C) a step of treating the aqueous solution obtained in the step (b) with a cation exchange resin to dealkalize, and (d) placing the aqueous solution obtained in the step (c) in a reaction vessel, It includes a step of hydrothermal treatment at a temperature of ˜350 ° C.

In the step (a), the zirconium oxide hydrate is one or more kinds of zirconic acid selected from zirconium oxychloride, zirconium oxysulfate, zirconium oxynitrate, zirconium oxyacetate, zirconium oxycarbonate and ammonium zirconium oxycarbonate. A neutralized reaction product obtained by adding ammonia or aqueous ammonia to an aqueous salt solution with stirring is preferably washed.
In the step (a), the alkali metal hydroxide is preferably potassium hydroxide.

An alkali metal hydroxide in the step (a) the addition amount of (MOH), the zirconium oxide hydrate relative _{(ZrO 2 · xH 2 O)} , the molar ratio _{(MOH / ZrO 2 · xH 2} O) And preferably in the range of 1/1 to 10/1.
In addition, in the step (a), the amount of hydrogen peroxide (H ₂ O ₂ ) added is the molar ratio (H ₂ O ₂ / ZrO ₂ ) with respect to the zirconium oxide hydrate (ZrO ₂ · xH ₂ O). XH ₂ O) is preferably in the range of 5/1 to 30/1.
Furthermore, the aqueous solution prepared in the step (a) preferably contains 0.3 to 5% by weight of a zirconium component on a ZrO ₂ conversion basis.

The silica sol used in the step (b) preferably contains 0.5 to 5% by weight of a silicon component on the basis of SiO ₂ conversion.
Moreover, it is preferable that the aqueous solution of the silicic acid solution added in the step (b) contains 0.5 to 5% by weight of a silicon component in terms of SiO ₂ .
Further, the amount of the aqueous solution containing the zirconium component in the step (b) is such that the zirconium component is represented by ZrO ₂ and the silicon component contained in the silica sol is represented by SiO ₂ with respect to the silica sol. The molar ratio (SiO ₂ / ZrO ₂ ) is preferably in the range of 1/1 to 5/1.

In the step (b), the addition amount of the aqueous solution of the silicic acid solution is such that the silicon component contained in the silicic acid solution is represented by SiO ₂ with respect to the aqueous solution containing the zirconium component added at the same time, and the zirconium component is represented by ZrO _2. Is preferably in the range of 1/16 to 1/1 in terms of molar ratio (ZrO ₂ / SiO ₂ ).
Moreover, it is preferable that the aqueous solution of the silicic acid solution added in the step (b) is obtained by diluting water glass with water and then treating with a cation exchange resin to dealkali.
Furthermore, in the step (b), the silica sol is preferably heated to a temperature of 70 to 95 ° C. before adding the aqueous solution containing the zirconium component and the aqueous solution of the silicic acid solution.
Furthermore, it is preferable to repeat the addition operation in the step (b) and the dealkalization operation in the step (c) a plurality of times.

The dealkalization operation in the step (c) is preferably performed so that the pH of the aqueous solution is in the range of 7.0 to 10.0.
Moreover, it is preferable to perform the hydrothermal treatment in the said process (d) over 10 to 100 hours in an autoclave.
Further, the chain silica-based fine particle group includes a silica-based fine particle coated with a composite oxide composed of at least zirconium, silicon, and oxygen, the silica-based fine particle coating material, or the composite oxide extending from the coating material. It is preferable to have a shape in which a plurality of materials are connected via a band-shaped substance.

On the other hand, the aqueous dispersion according to the present invention comprises a silica-based fine particle coated with a composite oxide comprising at least zirconium, silicon, and oxygen, the silica-based fine particle coating material or the composite oxide extending from the coating material. It is characterized by containing a group of chain silica-based fine particles connected by a plurality through a band-shaped substance.
Further, the organic solvent dispersion according to the present invention is obtained by subjecting the aqueous dispersion to a solvent substitution step. Silica-based fine particles coated with a composite oxide comprising at least zirconium, silicon and oxygen are used as the silica dispersion. It is characterized in that it contains a group of chain silica-based fine particles formed by connecting a plurality of fine-particle-based coating materials or a band-shaped material of the composite oxide extending from the coating material.

According to the method of the present invention, it is possible to stably produce an aqueous dispersion containing a group of chain silica-based fine particles coated with a composite oxide composed of at least zirconium, silicon and oxygen.
When the aqueous dispersion obtained from this method is dried using a spray dryer or the like and then fired as necessary, the silica-based fine particles coated with the composite oxide are converted into the silica-based fine particle coating material or the coating material. Thus, an amorphous dry powder or an amorphous fired powder of inorganic oxide fine particle groups having a unique shape such that a plurality of the complex oxide strips connected from each other are connected to each other can be obtained.

The amorphous dry powder and the amorphous fired powder of the inorganic oxide fine particle group obtained in this manner are obtained by coating the silica-based fine particles with the composite oxide. The surface properties of the powder and the amorphous fired powder are almost the same, and unevenness does not occur in the refractive index. Furthermore, the amorphous dry powder and the amorphous fired powder of the inorganic oxide fine particle group are excellent in mechanical strength, wear resistance, refractive index compatibility, radiopacity, etc. It can be suitably used as a filler.

In addition, the chain silica-based fine particle group contained in the aqueous dispersion has excellent characteristics such as wear resistance and refractive index adaptability, and is therefore preferably used for applications other than dental fillers. be able to. That is, when a paint containing the aqueous dispersion or the organic solvent dispersion, for example, a hard coating agent or an antireflection agent, is prepared and applied to a plastic substrate or paper, the wear resistance and reflectance of the surface Etc. can be greatly improved. In these applications, it is preferable to use the organic solvent dispersion rather than the water dispersion.

  Hereinafter, a method for producing an aqueous dispersion containing chain silica-based fine particle groups according to the present invention, an aqueous dispersion containing the silica-based fine particle groups, and an organic solvent dispersion thereof will be specifically described.

[Production method of aqueous dispersion]
The method for producing an aqueous dispersion containing the chain silica-based fine particle group according to the present invention,
A method for producing an aqueous dispersion containing a group of chain silica-based fine particles formed by coating the surface of silica-based fine particles with a composite oxide comprising at least zirconium, silicon and oxygen,
(A) By adding an alkali metal hydroxide and hydrogen peroxide to an aqueous solution containing zirconium oxide hydrate and stirring, an aqueous solution in which the zirconium oxide hydrate is peptized and dissolved is prepared. Process,
(B) a step of adding the aqueous solution obtained in the step (a) and an aqueous solution of a silicic acid solution with stirring to a silica sol in which silica-based fine particles having an average particle size of 2 to 300 nm are dispersed in water;
(C) a step of treating the aqueous solution obtained in the step (b) with a cation exchange resin to dealkalize, and (d) placing the aqueous solution obtained in the step (c) in a reaction vessel, It includes a step of hydrothermal treatment at a temperature of ˜350 ° C.
Furthermore, it will be as follows if said each process is explained in full detail.

Step (a)
The zirconium oxide hydrate referred to in the present invention is represented by the chemical formula ZrO ₂ .xH ₂ O, and this includes zirconium hydroxide (Zr (OH) _n ).
The zirconium oxide hydrate is known to dissolve in an acid or an aqueous solution containing an acid, but hardly dissolve in an aqueous solution containing water or an alkali.
Therefore, in this step (a), a suspension aqueous solution containing zirconium hydroxide in pure water or distilled water is prepared, and an alkali metal hydroxide such as potassium or sodium (that is, potassium hydroxide, hydroxide) is prepared. Sodium and the like) and hydrogen peroxide are added and stirred to prepare a mixed aqueous solution (hereinafter referred to as “mixed aqueous solution- (1)”) in which the zirconium oxide hydrate is peptized and dissolved. Here, it is preferable to use potassium hydroxide as the alkali metal hydroxide. This is because the use of potassium hydroxide facilitates the aforementioned peptization as compared with sodium hydroxide.

The alkali metal hydroxide (M ₂ O) is in a molar ratio (M ₂ O / ZrO ₂ · xH) with respect to zirconium oxide hydrate (ZrO ₂ · xH ₂ O) contained in the aqueous suspension. ₂ O) is preferably added at a rate such that 1/1 to 10/1, preferably 2/1 to 5/1. Here, when the molar ratio is less than 1/1, peptization of zirconium oxide hydrate does not proceed. When the molar ratio exceeds 10/1, high peptization is obtained, but excess alkali Since metal ions are contained in the aqueous solution and need to be removed (using a cation exchange resin) in a subsequent step, it is not economical.

The hydrogen peroxide (H ₂ O ₂ ) is in a molar ratio (H ₂ O ₂ / ZrO ₂ .xH ₂ ) with respect to zirconium oxide hydrate (ZrO ₂ .xH ₂ O) contained in the aqueous suspension. O) is preferably added at a ratio of 5/1 to 30/1, preferably 10/1 to 25/1. Here, when the molar ratio is less than 5/1, the peptization of the zirconium oxide hydrate does not progress, and when the molar ratio exceeds 30/1, the dissolution of the zirconium oxide hydrate is accelerated. Although the time required for dissolution is shortened, a large amount of unreacted hydrogen peroxide remains in the system, which is not economically preferable.
Furthermore, the hydrogen peroxide is preferably added as a hydrogen peroxide solution having a concentration of 18 to 35% by weight.

The zirconium oxide hydrate can be prepared by a conventionally known method such as hydrolysis of a zirconium salt in an aqueous solution or addition of alkali or ammonia to the aqueous solution to cause a neutralization reaction. In the present invention, however, zirconium oxychloride (ZrOCl ₂ · xH ₂ O), zirconium oxysulfate (ZrOSO ₄ · xH ₂ O), zirconium oxynitrate (ZrO (NO ₃ ) ₂ · xH ₂ ) is added to pure water or distilled water. O), zirconium oxyacetate (ZrO (C ₂ H ₃ O ₂ ) ₂ ), zirconium oxycarbonate (ZrOCO ₃ · xH ₂ O) and ammonium oxycarbonate ((NH ₄ ) ₂ ZrO (CO ₃ ) ₂ ) Neutralization reaction product (zirconium oxide hydrate) obtained by adding ammonia or aqueous ammonia to an aqueous solution in which one or more zirconate salts are dissolved under stirring to cause a neutralization reaction It is preferable to use one that has been sufficiently washed with pure water or distilled water. Further, it is desirable to use zirconium oxychloride (ZrOCl ₂ .8H ₂ O) as the zirconate. The zirconium oxychloride, the zirconium oxysulfate, the zirconium oxynitrate, the zirconium oxyacetate and the zirconium oxycarbonate are sometimes referred to as zirconyl hydrochloride, zirconyl sulfate, zirconyl nitrate, zirconyl acetate and zirconyl carbonate, respectively. .

Further, instead of the zirconate, zirconium carbonate (ZrCO ₄ · ZrO ₂ · xH ₂ O), zirconium sulfate (Zr (SO ₄ ) ₂ · xH ₂ O), zirconium chloride (ZrCl ₂ , ZrCl ₃ or ZrCl _4). ) And zirconium nitrate (Zr (NO ₃ ) ₄ .xH ₂ O) may be used, or one or more zirconates may be used.
The content of the zirconate salt in the aqueous solution is preferably 10 to 20% by weight, preferably 13 to 17% by weight.

The ammonia (NH ₃ ) or aqueous ammonia (NH ₄ OH) has a molar ratio (NH ₃ / ZrOX _n or NH ₄ OH / ZrOX _n ) with respect to the zirconate salt (ZrOX _n ) contained in the aqueous solution. It is preferable to add at a ratio of 13/7 to 13/2, preferably 13/5 to 13/4. Here, when the molar ratio is less than 13/7, neutralization of the zirconate is not sufficient, so that a part of the zirconate remains as it is, and when the molar ratio exceeds 13/2, ammonia is removed. Since it is added excessively, it takes time to clean the residual ammonia, which is not preferable.
Further, the ammonia water is preferably added as ammonia water having a concentration of 5 to 15% by weight.

Moreover, it is preferable to perform the said neutralization reaction at the temperature of 5-20 degreeC, Preferably it is 10-15 degreeC. Here, when the temperature exceeds 20 ° C., zirconium oxide hydrate (for example, zirconium hydroxide and the like) generated by neutralization of the zirconate salt changes with time, which is not preferable.

Zirconium oxide hydrate obtained from the neutralization reaction is separated by filtration, and then sufficiently washed with pure water or distilled water, and unreacted substances (such as ZrOX _n ) and reaction by-products (NH in the neutralization reaction) are obtained. ₄ X etc.) should be removed as much as possible.
Zirconium component (zirconia of zirconium oxide hydrate) contained by dissolving in the mixed aqueous solution- (1) thus obtained is not particularly limited, but is based on ZrO ₂ conversion standard. It is desirable to be in the range of 0.3 to 5% by weight.

Step (b)
In this step (b), the mixed aqueous solution- (1) and silicic acid obtained in the step (a) are stirred in a silica sol in which silica-based fine particles having an average particle size of 2 to 300 nm are dispersed in water. Each of the aqueous solutions is added.
Here, as the silica sol, a commercially available product (for example, SI-30 manufactured by Catalyst Chemical Industry Co., Ltd.) can be used as long as it contains silica-based fine particles having an average particle diameter of 2 to 300 nm. . Here, when the average particle diameter is less than 2 nm, the mechanical strength of the dental filler using the particles, particularly the compressive strength and bending strength are lowered, and when the average particle diameter exceeds 300 nm, the particles When a tooth is restored by using the dental filler containing it, the smoothness of the polished surface becomes insufficient, which is not preferable. In addition, the average particle diameter here shows the result measured using the laser diffraction scattering method.
The concentration of the silica-based fine particles contained in the silica sol is preferably in the range of 0.5 to 5% by weight. Here, when the concentration is less than 0.5% by weight, it is difficult to economically obtain the inorganic oxide fine particles, and when the concentration exceeds 5% by weight, the mixed aqueous solution- (1) and When an aqueous solution of the silicic acid solution is added, the mixed solution becomes unstable and particle aggregation occurs, which makes it difficult to obtain chain-like inorganic oxide fine particles.

Furthermore, the zirconium component contained in the mixed aqueous solution- (1) varies depending on the concentration of the silica-based fine particles contained in the silica sol, as well as the nature and concentration of the silicic acid solution added separately in this step, It is preferable to add after adjusting to 0.3 to 5% by weight, preferably 0.5 to 3% by weight on the basis of ZrO ₂ conversion. Here, when the content is less than 0.3% by weight, it becomes difficult to obtain the inorganic oxide fine particles economically, and when the content exceeds 5% by weight, the stability of the mixed aqueous solution is increased. Is unfavorable, and the viscosity of the aqueous solution tends to increase.

On the other hand, the aqueous solution of the silicic acid solution (hereinafter sometimes simply referred to as “silicic acid solution”) was dealkalized by treating a silicate aqueous solution such as an alkali metal silicate or an organic base silicate with a cation exchange resin. Things are used. Examples of these silicates include alkali metal silicates such as sodium silicate (water glass) and potassium silicate, and silicates of organic bases such as quaternary ammonium silicate.
Among the aqueous solutions of the silicic acid solution, the pH is in the range of 2 to 4, preferably 2 to 3, and the content of the silicon component is 0.5 to 5% by weight, preferably 3 to 4% by weight on the basis of SiO ₂ conversion. It is preferable to use the thing in the range. Here, when the pH is less than 2, the amount of the cation exchange resin required for the treatment and the treatment time are more than necessary, which is not economical, and when the pH exceeds 4, the degree of dealkalization. Is not preferable since the stability of the resulting silicic acid solution is deteriorated. Furthermore, when the content is less than 0.5% by weight, it becomes difficult to obtain the inorganic oxide fine particles economically, and when the content exceeds 5% by weight, the stability of the silicic acid solution is poor. This is not preferable.
As an aqueous solution of the silicic acid solution having such properties, it is preferable to use a solution obtained by diluting water glass (sodium silicate) with water and then treating it with a cation exchange resin to dealkalize.

In the mixed aqueous solution- (1) and the aqueous solution of the silicic acid solution, the zirconium component contained in the mixed aqueous solution- (1) is represented by ZrO ₂ , and the silicon component contained in the silicic acid solution is represented by SiO _2- (1 ), The molar ratio (ZrO ₂ / SiO _2- (1)) is adjusted to 1/16 to 1/1, preferably 1/8 to 1/2. It is preferred to add both slowly. Here, when the molar ratio is less than 1/16, it is difficult to obtain chain-like inorganic oxide fine particles, and when the molar ratio exceeds 1/1, while being added to the silica sol In addition, the liquid mixture becomes unstable and the particles are aggregated, which is not preferable.
Further, the amount of addition to the silica sol varies depending on the degree of coating on the silica-based fine particles contained in the silica sol, but when the silica-based fine particles are represented by SiO _2- (2), the weight ratio It is preferable that {(ZrO ₂ / SiO _2- (1)) / SiO _2- (2)} is in the range of 7/100 to 15/10, preferably 5/10 to 1/1. Here, when the weight ratio is less than 7/100, it becomes difficult to obtain chain-like inorganic oxide fine particles, and when the weight ratio exceeds 15/10, while being added to the silica sol In addition, the liquid mixture becomes unstable and the particles are aggregated, which is not preferable.

The silica sol is preferably heated to a temperature of 70 to 95 ° C., preferably 80 to 90 ° C. before adding the mixed aqueous solution- (1) and the aqueous solution of the silicic acid solution. Here, when the temperature is less than 70 ° C., the hydrolysis reaction of the zirconium component and the silicic acid liquid component does not proceed, and when the temperature exceeds 95 ° C., moisture in the silica sol starts to evaporate. The mixed aqueous solution- (1) and the aqueous solution of the silicic acid solution may be used after being heated, but can be used as they are at room temperature.
Further, the addition of the aqueous solution of the mixed aqueous solution- (1) and the silicic acid solution varies depending on the concentration of the components contained in these aqueous solutions and the addition amount (total amount), but each of them slowly takes 4 to 24 hours. It is preferable to carry out.

In this way, when the mixed aqueous solution- (1) and the aqueous solution of the silicic acid solution are added to the silica sol while stirring, the hydrolysis reaction of the zirconium component and the silicon component is carried out in the mixed aqueous solution- (2). Occurring, the surface of the silica-based fine particles contained in the silica sol is coated with the partial hydrolyzate or hydrolyzate of the component.
With the addition of the mixed aqueous solution- (1) exhibiting strong alkalinity, the pH of the mixed aqueous solution- (2) increases with time, so that the pH of the mixed aqueous solution becomes 11, preferably 10.5. Therefore, it is desirable to stop the addition of the mixed aqueous solution- (1) and the silicic acid solution. Here, when the pH exceeds 11, the silica-based fine particles contained in the silica sol start to dissolve in the mixed aqueous solution- (2) due to alkali, which is not preferable.
Therefore, when the addition of the mixed aqueous solution- (2) and the silicic acid solution is not completed at the stage when the pH reaches 11, after performing dealkalization in the step (c) described below, this operation is performed again. Or it is preferable to repeat.

  In addition, when the surface of the silica-based fine particles is coated with a complex oxide containing titanium or aluminum as necessary, in addition to the above components, tetramethyl titanate, tetraisopropyl titanate, tetra It can be carried out by appropriately adding an aqueous solution of a titanium compound such as n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate or an aqueous aluminum compound such as sodium aluminate.

Step (c)
In this step (c), the mixed aqueous solution- (2) obtained in the step (b) is treated with a cation exchange resin to be dealkalized.
Although it does not restrict | limit especially as a cation exchange resin used here, It is preferable to use cation exchange resins, such as SK1BH made from Mitsubishi Chemical Corporation.
In this step, the mixed aqueous solution- (2) is preferably dealkalized so that the pH of the mixed aqueous solution is 7.0 to 10.0, preferably 8.5 to 9.5. Here, when the pH is less than 7.0, dealkalization in the mixed solution proceeds excessively, the mixed solution becomes unstable, causing aggregation of particles, and the pH exceeds 10.0. In addition, since the silica-based fine particles contained in the silica sol begin to be dissolved by alkali during the addition of the mixed aqueous solution- (1) and the silicic acid solution, the mixed aqueous solution- (2) is not preferable.

  The mixed aqueous solution- (3) obtained from this step returns to the step (b) as described above when it is necessary to further add the mixed aqueous solution- (2) and the silicic acid solution to the mixed aqueous solution. Then, the operation in the same process is performed again, and when it is not necessary, it is subjected to the process (d) described below. In addition, you may perform the operation of the said process (b) and the said process (c) repeatedly as needed.

Step (d)
In this step (d), the mixed aqueous solution- (3) obtained in the step (c) is put in a reaction vessel and hydrothermally treated at a temperature of 100 to 350 ° C.
Here, the reactor is not particularly limited as long as it is a pressure-resistant and heat-resistant container that can withstand a pressure of 0.5 to 16.5 MPa, but it is preferable to use a stainless steel autoclave.

The hydrothermal treatment is preferably performed at a temperature of 100 to 350 ° C., preferably 150 to 200 ° C., for 10 to 100 hours, preferably 20 to 40 hours. Here, when the hydrothermal temperature is less than 100 ° C., a partial hydrolyzate and / or a hydrolyzate condensation reaction obtained from a hydrolysis reaction of the zirconium component and the silicon component contained in the mixed aqueous solution Since it does not proceed sufficiently, it is difficult to obtain a silica fine particle group (chain inorganic oxide fine particle group) covered with a composite oxide composed of at least zirconium, silicon and oxygen. In addition, in order to perform hydrothermal treatment at a temperature of 350 ° C. or higher, a pressure-resistant and heat-resistant container that can withstand a pressure of 16.5 Mpa or more is required, and further, it is not economical in terms of energy consumption.
Furthermore, if the hydrothermal time is less than 10 hours, the partial hydrolyzate obtained from the hydrolysis reaction of the zirconium component and the silicon component and / or the condensation reaction of the hydrolyzate does not proceed sufficiently. It becomes difficult to obtain a silica fine particle group (chain inorganic oxide fine particle group) coated with a composite oxide composed of silicon and oxygen. Further, even if the hydrothermal time exceeds 100 hours, there is not much influence in forming the silica fine particle group (chain inorganic oxide fine particle group) coated with the composite oxide, so more time is taken. That is not a good idea.

  In this way, a mixed aqueous solution- (4) containing silica fine particle groups (chain inorganic oxide fine particle groups) coated with a composite oxide composed of at least zirconium, silicon and oxygen is obtained. That is, the mixed aqueous solution- (4) is an aqueous dispersion containing the chain inorganic oxide fine particle group according to the present invention. More specifically, the mixed aqueous solution is coated with a composite oxide composed of at least zirconium, silicon and oxygen. An aqueous dispersion containing a group of chain silica-based fine particles obtained by connecting a plurality of the silica-based fine particles via a coating material of the silica-based fine particles or a band-shaped material of the composite oxide extending from the coating material It is.

Solvent replacement step The aqueous dispersion obtained from the step (d) further contains an organic solvent containing chain-like inorganic oxide fine particles by replacing the water contained in the aqueous dispersion with an organic solvent as necessary. A solvent dispersion can be obtained.
The organic solvent varies depending on the application, but alcohols such as methanol, ethanol, propanol, butanol, diacetone alcohol, furfuryl alcohol, tetrahydrfurfuryl alcohol, ethylene glycol, hexylene glycol, acetic acid Esters such as methyl ester and acetic acid ethyl ester, diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and other ethers, acetone, methyl ethyl ketone, acetyl acetone, aceto Mention may be made of ketones such as acetates. Moreover, these organic solvents can also be used individually or in mixture of 2 or more types.

Furthermore, as a method for performing the solvent substitution, a conventionally known method can be employed, for example, a method using a rotary evaporator or a method using an ultrafiltration membrane. A simple example of these methods is as follows.
a) Rotary evaporator method The aqueous dispersion is put into a rotary evaporator flask, and an organic solvent (for example, methyl ethyl ketone) is put into the flask. Next, the rotary evaporator is driven to rotate the flask at a speed of 30 to 120 rpm under a temperature condition of 50 to 90 ° C. and a reduced pressure condition of −0.05 to −0.1 MPa. Then, since water contained in the aqueous dispersion evaporates, it is cooled and discharged out of the system.
Furthermore, an organic solvent dispersion in which the water and the organic solvent are replaced by a solvent is obtained by continuously performing the above operation for a necessary time.

b) Ultrafiltration membrane method The same amount of the aqueous dispersion and the organic solvent (for example, methanol) are mixed, and this is applied to a commercially available ultrafiltration membrane device (Asahi Kasei Chemicals Co., Ltd., Microza UF). The filtered water (including water and organic solvent) separated by filtration is discharged out of the system. This operation is continuously performed, and when the amount of the mixed solution becomes half, the same amount of the organic solvent is further mixed. Further, by repeating the above operation, an organic solvent dispersion in which the water and the organic solvent are replaced with a solvent can be obtained.

[Aqueous dispersion containing chain silica fine particles]
The aqueous dispersion containing the chain silica-based fine particle group according to the present invention,
A plurality of silica-based fine particles coated with a composite oxide comprising at least zirconium, silicon and oxygen are connected via a coating material of the silica-based fine particles or a band-shaped material of the composite oxide extending from the coating material. It contains a chain silica-based fine particle group.
Here, the composite oxide covering the silica-based fine particles is a composite oxide composed of at least zirconium, silicon and oxygen, and a part of the structural formula is as follows.

｜ ｜
-O-Zr-O-Si-O- (I)
｜ ｜

In addition, the chain-like inorganic oxide fine particle group contained in the dispersion according to the present invention has a shape generally shown in the electron micrograph of FIG.

[Organic solvent dispersion containing chain silica fine particles]
The organic solvent dispersion containing the chain silica-based fine particle group according to the present invention,
A plurality of silica-based fine particles coated with a composite oxide comprising at least zirconium, silicon and oxygen are connected via a coating material of the silica-based fine particles or a band-shaped material of the composite oxide extending from the coating material. It contains a chain silica-based fine particle group.
Since this organic solvent dispersion is the same as the aqueous dispersion except that an organic solvent is used instead of water as a dispersion medium, the description thereof is omitted here.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

[Preparation Example 1]
Preparation of Zirconium Oxide Hydrate 250 kg of zirconium oxychloride (ZrOCl ₂ .8H ₂ O, manufactured by Taiyo Mining Co., Ltd.) was added to 4375 kg of pure water at a temperature of 15 ° C. and stirred to dissolve the zirconium oxychloride.
Further, in this aqueous solution of zirconium oxychloride, ammonia water having a concentration of 15% by weight is added. L was slowly added under stirring, and the zirconium oxychloride was neutralized under a temperature condition of 15 ° C. to obtain a slurry containing zirconium oxide hydrate precipitates. The pH of this slurry was 8.5.
Subsequently, this slurry was filtered, and the obtained cake-like substance was repeatedly washed with pure water to remove by-products and unreacted substances in the neutralization reaction.
As a result, 860 kg of a cake-like substance containing 10% by weight of zirconium oxide hydrate on a ZrO ₂ conversion basis and the remainder being moisture was obtained.

[Preparation Example 2]
Preparation of silicic acid solution After diluting 10 kg of commercially available water glass (Asahi Glass S-Tech Co., Ltd.) with 38 kg of pure water, it is dealkalized using a cation exchange resin (Mitsubishi Chemical Corporation). 9 kg of a silicic acid solution having a pH of 3 and a SiO ₂ concentration of 4% by weight was prepared. Thereafter, 10768 g of this silicic acid solution and 14860 g of pure water were mixed to prepare 25628 g of a 2 wt% silicic acid solution.

Preparation of aqueous dispersion [Example 1]
45800 g of pure water was added to 5416 g of the cake-like substance containing zirconium oxide hydrate prepared in Preparation Example 1, and 1024 g of potassium hydroxide containing 85% by weight of potassium hydroxide (manufactured by Kanto Chemical Co., Ltd.) was further stirred. After making it alkaline by adding, 10248 g of hydrogen peroxide containing 35% by weight of hydrogen peroxide (manufactured by Hayashi Pure Chemical Industries, Ltd.) was added.
Furthermore, this mixed aqueous solution was allowed to stand for 1 hour with stirring, and the zirconium oxide hydrate was peptized and dissolved in the aqueous solution. Next, 39991 g of ice water obtained by freezing pure water was added, and the aqueous solution whose temperature was increased by an exothermic reaction was cooled to a temperature of 30 ° C. or lower. As a result, 102400 g of a mixed aqueous solution (hereinafter referred to as Example Preparation Solution 1A) containing 0.5% by weight of the zirconium component on the basis of ZrO ₂ and having a pH of about 11 was obtained.

47,900 g of pure water was added to 3336 g of silica sol containing 30% by weight of silica fine particles having an average particle size of 12 nm (SI-30 manufactured by Catalyst Kasei Kogyo Co., Ltd.) and stirred sufficiently to obtain 51236 g of silica sol having a silica fine particle concentration of 2 wt%. .
Next, the silica sol was heated to 90 ° C., and while stirring it, 12814 g of an aqueous solution of the silicic acid solution prepared in Preparation Example 2 and 51200 g of the Example Preparation Solution 1A were slowly added over 10 hours. As a result, 115250 g of a mixed aqueous solution having a pH of about 11 (hereinafter referred to as Example Preparation Solution 1B- (1)) was obtained.
Next, the Example preparation solution 1B- (1) was treated with a cation exchange resin (SK1BH, manufactured by Mitsubishi Chemical Corporation) to dealkalize. As a result, 117250 g of a mixed aqueous solution having a pH of about 9.5 (hereinafter referred to as Example Preparation Solution 1C- (1)) was obtained.

Furthermore, while heating Example Preparation Solution 1C- (1) to 90 ° C. and stirring it, 12814 g of the aqueous solution of silicic acid solution prepared in Preparation Example 2 and 51200 g of Example Preparation Solution 1A were taken for 10 hours. Slowly added. As a result, 181264 g of a mixed aqueous solution having a pH of about 11 (hereinafter referred to as Example Preparation Solution 1B- (2)) was obtained.
Next, the Example preparation solution 1B- (2) was treated with a cation exchange resin (SK1BH, manufactured by Mitsubishi Chemical Corporation) to dealkalize. As a result, 182264 g of a mixed aqueous solution having a pH of about 9.5 (hereinafter referred to as Example Preparation Solution 1C- (2)) was obtained.

Next, 100200 g of Example Preparation Solution 1C- (2) was placed in a stainless steel autoclave (manufactured by Pressure Glass Industrial Co., Ltd.) and hydrothermally treated at a temperature of 165 ° C. for 18 hours. Thereby, a mixed aqueous solution containing the solid content of the surface-coated inorganic oxide fine particle group 99750 g (hereinafter referred to as Example Preparation Solution 1D) was obtained.

A sample of the inorganic oxide fine particle group was taken out from the Example preparation liquid 1D thus obtained, and this was taken out using a field emission scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation) at a magnification of 25. The result of taking an electron micrograph at a magnification of 10,000 was as shown in FIG.
As a result, the inorganic oxide fine particle group includes a plurality of silica-based fine particles coated with the composite oxide via a coating material of the silica-based fine particles or a band-shaped material of the composite oxide extending from the coating material. , It was found to have a chain shape formed by linking.

Further, when the X-ray diffraction peak of the sample of the inorganic oxide fine particle group was measured with an X-ray diffractometer (RINT-1400, X-ray diffraction method), no crystalline peak was observed and amorphous inorganic oxidation was not observed. It was found to be a fine particle group. Using these field emission electron microscopes (Hitachi High-Technologies Corporation's FE-TEM), these samples were measured and analyzed for the composition of the coating material (select a band-shaped material extending between silica-based fine particles). The coating material was found to be a complex oxide composed of zirconium, silicon and oxygen.
These measurement results are shown in Table 1 for easy comparison.

[Example 2 and Comparative Example 1]
In Example 1, 15000 g of Preparation Solution 2C- (2) was prepared in the same manner as in Example 1 Preparation Solution 1C- (2).
Next, 4800 g of each of the preparation solutions 2C- (2) was taken out and placed in a stainless steel autoclave (manufactured by Pressure Glass Industry Co., Ltd.) at temperatures of 90 ° C., 110 ° C., and 300 ° C., respectively. Hydrothermal treatment was performed for 18 hours. As a result, mixed aqueous solutions containing solids composed of surface-coated inorganic oxide fine particle groups (hereinafter referred to as Comparative Example Preparation Solution 1D, Example Preparation Solution 2D- (1) and Example Preparation Solution 2D- (2), respectively). )

  A sample of the inorganic oxide fine particle group is taken out from the comparative example preparation liquid 1D, the example preparation liquid 2D- (1) and the example preparation liquid 2D- (2) thus obtained, and this is electrolytically released. Using a scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation), the shape of the inorganic oxide fine particle group obtained by taking an electron micrograph at a magnification of 250,000 times was observed. Further, a sample of the inorganic oxide fine particle group was taken out from the comparative preparation liquid 1D, the exemplary preparation liquid 2D- (1), and the exemplary preparation liquid 2D- (2). These were measured with an X-ray diffractometer (RINT-1400, X-ray diffractometry) to determine whether or not the resulting inorganic oxide fine particle group was amorphous. In the same manner as in Example 1, these samples were subjected to the above-mentioned coating material (a band-shaped material extending between silica-based fine particles) using a field emission transmission electron microscope (FE-TEM manufactured by Hitachi High-Technologies Corporation). The composition was measured and analyzed to determine whether a composite oxide composed of zirconium, silicon and oxygen was present in the coating material. The results are shown in Table 1.

[Example 3 and Comparative Example 2]
In Example 1, 98 kg of Preparation Solution 2A was prepared in the same manner as in Example 1 Preparation Solution 1A.
Next, the silicic acid solution prepared in Preparation Example 2 and the preparation solution 2A were added in two portions to 13480 g of silica sol heated to 90 ° C. in the same manner as in Example 1 in the following ratio. In addition, dealkalization treatment was performed. The molar ratio of below represents the silicon components contained in the silicic acid solution with SiO _2, showing a further obtained when the zirconium components contained in the aqueous solution, expressed in ZrO _2.

Silicic acid solution (g) Preparation solution 2A (g) molar ratio (SiO ₂ / ZrO ₂ )
Mixed aqueous solution 1 10784.0 41336.0 2/1
Mixed aqueous solution 2 5055.0 20200.0 2/1
Mixed aqueous solution 3 8087.5 32350.0 2/1
Mixed aqueous solution 4 337.0 1348.0 2/1

  Subsequently, the mixed aqueous solutions 1 to 4 (that is, Comparative Example Preparation Solution 2C- (1), Example Preparation Solution 3C- (1), Example Preparation Solution 3C- (2), and Comparative Example Preparation Solution 2C- (2 2000 g each was taken out from the sample and placed in a stainless steel autoclave (manufactured by Pressure Glass Industrial Co., Ltd.), and hydrothermally treated at a temperature of 160 ° C. for 16 hours. As a result, mixed aqueous solutions containing solids composed of surface-coated inorganic oxide fine particle groups (hereinafter referred to as Comparative Example Preparation Solution 2D- (1), Example Preparation Solution 3D- (1), and Example Preparation Solution 3D-, respectively). (2) and Comparative Example Preparation Solution 2D- (2)).

Of the thus-obtained Comparative Example Preparation Solution 2D- (1), Example Preparation Solution 3D- (1), Example Preparation Solution 3D- (2), and Comparative Example Preparation Solution 2D- (2) A sample of oxide fine particle group was taken out and the shape of inorganic oxide fine particle group obtained by taking an electron micrograph of 250,000 times magnification using a field emission scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation) Was observed. Further, inorganic oxide fine particles from the above-mentioned Comparative Example Preparation Solution 2D- (1), Example Preparation Solution 3D- (1), Example Preparation Solution 3D- (2) and Comparative Example Preparation Solution 2D- (2) As in Example 1, these samples were measured for X-ray diffraction peaks with an X-ray diffractometer (RINT-1400, X-ray diffraction method), and the resulting inorganic oxide fine particle group was amorphous. We checked whether it was quality. In the same manner as in Example 1, these samples were subjected to the above-mentioned coating material (a band-shaped material extending between silica-based fine particles) using a field emission transmission electron microscope (FE-TEM manufactured by Hitachi High-Technologies Corporation). The composition was measured and analyzed to determine whether a composite oxide composed of zirconium, silicon and oxygen was present in the coating material. The results are shown in Table 1.

[Example 4 and Comparative Example 3]
In Example 1, 60.0 kg of Preparation Solution 3A was prepared in the same manner as in Example 1 Preparation Solution 1A.
Next, 6740 g of the silicic acid solution prepared in Preparation Example 2 and 26960 g of the above-mentioned Preparation Solution 3A are added in two portions to 13480 g of silica sol heated to 50 ° C. and 80 ° C. in the same manner as in Example 1. Then, dealkalization treatment was performed.
Next, the obtained mixed aqueous solutions (that is, Comparative Preparation Liquid 3C and Example Preparation Liquid 4C, respectively) were put in a stainless steel autoclave (manufactured by Pressure Glass Industry Co., Ltd.), and each 160 Hydrothermal treatment was performed at a temperature of ° C for 16 hours. As a result, mixed aqueous solutions containing the solid content of the surface-coated inorganic oxide fine particle groups (hereinafter referred to as Comparative Example Preparation Solution 3D and Example Preparation Solution 4D, respectively) were obtained.

A sample of the inorganic oxide fine particle group was taken out from the comparative example preparation liquid 3D and the example preparation liquid 4D thus obtained, and this was taken out by using a field emission scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation). ) Was used to observe the shape of the inorganic oxide fine particle group obtained by taking an electron micrograph at a magnification of 250,000 times. Further, samples of the inorganic oxide fine particle group are taken out from the comparative preparation liquid 3D and the exemplary preparation liquid 4D, and in the same manner as in the first embodiment, these samples are obtained by using an X-ray diffractometer (RINT-1400, X-ray diffraction). The X-ray diffraction peak was measured by (Method), and it was examined whether the obtained inorganic oxide fine particle group was amorphous. In the same manner as in Example 1, these samples were subjected to the above-mentioned coating material (a band-shaped material extending between silica-based fine particles) using a field emission transmission electron microscope (FE-TEM manufactured by Hitachi High-Technologies Corporation). The composition was measured and analyzed to determine whether a composite oxide composed of zirconium, silicon and oxygen was present in the coating material. The results are shown in Table 1.

[Comparative Example 4]
28 kg of the preparation liquid 4A was prepared in the same manner as the preparation liquid 1A of the example in Example 1.
Next, 6740 g of the silicic acid solution prepared in Preparation Example 2 and 26960 g of the preparation solution 4A were added at once to 13480 g of silica sol heated to 90 ° C., and dealkalized.
Next, the obtained mixed aqueous solution (that is, Comparative Example Preparation Solution 4C) was put into a stainless steel autoclave (manufactured by Pressure Glass Industry Co., Ltd.), and each was at a temperature of 160 ° C. for 16 hours. Hydrothermal treatment was performed. This obtained the mixed aqueous solution (henceforth the comparative example preparation liquid 4D) containing the solid content which consists of inorganic oxide fine particle groups.

A sample of the inorganic oxide fine particle group was taken out from the comparative preparation liquid 4D obtained in this way, and this was taken out using a field emission scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation) at a magnification of 25. The shape of the inorganic oxide fine particle group which took the electron micrograph of 10,000 times was observed. Further, a sample of the inorganic oxide fine particle group is taken out from the comparative preparation liquid 4D, and X-ray diffraction is performed using an X-ray diffractometer (RINT-1400, X-ray diffractometry) in the same manner as in Example 1. The peak was measured and it was investigated whether the obtained inorganic oxide fine particle group was amorphous. In the same manner as in Example 1, these samples were subjected to the above-mentioned coating material (a band-shaped material extending between silica-based fine particles) using a field emission transmission electron microscope (FE-TEM manufactured by Hitachi High-Technologies Corporation). The composition was measured and analyzed to determine whether a composite oxide composed of zirconium, silicon and oxygen was present in the coating material. The results are shown in Table 1.

[Comparative Example 5]
A silica sol containing 10% by weight of silica fine particles having an average particle diameter of 17 nm on a basis of SiO ₂ (catalyst S-20L, manufactured by Catalyst Chemical Industry Co., Ltd.) was diluted with distilled water to obtain 1867 g of silica sol containing 3% by weight of silica fine particles. Obtained. After adding 12 g of NaOH aqueous solution having a concentration of 3 wt% and 407 g of zirconyl ammonium carbonate aqueous solution containing 4 wt% of zirconium component based on ZrO ₂ (Zircosol AC-7, manufactured by Daiichi Elemental Chemical Co., Ltd.) Then, 2286 g of these mixed slurry liquids (hereinafter referred to as Comparative Example Preparation Liquid 5D) were prepared by stirring for 15 minutes.

A sample of the inorganic oxide fine particle group was taken out of the comparative preparation liquid 5D thus obtained, and this was taken using a field emission scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation) at a magnification of 25. The shape of the inorganic oxide fine particle group which took the electron micrograph of 10,000 times was observed. Further, a sample of the inorganic oxide fine particle group is taken out from the comparative preparation liquid 5D, and X-ray diffraction is performed using an X-ray diffractometer (RINT-1400, X-ray diffraction method) in the same manner as in Example 1. The peak was measured and it was investigated whether the obtained inorganic oxide fine particle group was amorphous. In the same manner as in Example 1, these samples were subjected to the above-mentioned coating material (a band-shaped material extending between silica-based fine particles) using a field emission transmission electron microscope (FE-TEM manufactured by Hitachi High-Technologies Corporation). The composition was measured and analyzed to determine whether a composite oxide composed of zirconium, silicon and oxygen was present in the coating material. The results are shown in Table 1.

In Table 1 above, a circle mark is a complex oxide composed mostly of zirconium, silicon and oxygen, a triangle mark is a part of the complex oxide, and a cross mark is It means that most of them are not the complex oxide.

[Example 5]
In the same manner as in Example 1, the preparation liquid 5D (12D) was prepared in the same manner as the above-mentioned preparation liquid 1D.
Next, the prepared solution 5D was applied to an ultrafiltration membrane device (manufactured by Asahi Kasei Chemicals Corporation, Microza UF), and the water contained in the prepared solution was solvent-substituted with methanol (organic solvent). The specific method is described as follows.
(1) The prepared solution 5D (10 kg) and methanol (10 kg) were mixed, and this mixed solution was applied to an ultrafiltration membrane device, and filtrated water (including water and methanol) was discharged out of the system. This operation was continuously performed, and when the amount of the mixed solution reached about 10 kg, 10 kg of methanol was added to the mixed solution, and the same operation was further performed.
(2) The above operation was repeated until the water concentration contained in the mixed solution reached 0.5% by weight.
This obtained the mixed methanol liquid (henceforth Example preparation liquid 5D) containing the solid content which consists of inorganic oxide fine particle groups.

An electron micrograph of a sample of inorganic oxide fine particles from Example Powder 1A- (1) produced in Example 1 using a field emission scanning electron microscope (FE-SEM manufactured by Hitachi High-Technologies Corporation). The result of taking (magnification 250,000 times) is shown.

Claims (18)

A method for producing an aqueous dispersion containing a group of chain silica-based fine particles formed by coating the surface of silica-based fine particles with a composite oxide comprising at least zirconium, silicon and oxygen,
(A) By adding an alkali metal hydroxide and hydrogen peroxide to an aqueous solution containing zirconium oxide hydrate and stirring, an aqueous solution in which the zirconium oxide hydrate is peptized and dissolved is prepared. Process,
(B) a step of adding the aqueous solution obtained in the step (a) and an aqueous solution of a silicic acid solution with stirring to a silica sol in which silica-based fine particles having an average particle size of 2 to 300 nm are dispersed in water;
(C) a step of treating the aqueous solution obtained in the step (b) with a cation exchange resin to dealkalize, and (d) placing the aqueous solution obtained in the step (c) in a reaction vessel, A method for producing an aqueous dispersion containing chain silica-based fine particle groups, comprising a step of hydrothermal treatment at a temperature of ˜350 ° C.   In the step (a), the zirconium oxide hydrate is selected from the group consisting of zirconium oxychloride, zirconium oxysulfate, zirconium oxynitrate, zirconium oxyacetate, zirconium oxycarbonate, and ammonium zirconium oxycarbonate. The aqueous dispersion containing chain silica-based fine particle groups according to claim 1, wherein a neutralized reaction product obtained by adding ammonia or aqueous ammonia to an aqueous salt solution with stirring is washed. Manufacturing method.   The method for producing an aqueous dispersion containing chain silica-based fine particle groups according to any one of claims 1 to 2, wherein the alkali metal hydroxide in the step (a) is potassium hydroxide. . The addition amount of the alkali metal hydroxide (MOH) in the step (a) the zirconium oxide hydrate relative _{(ZrO 2 · xH 2 O)} , the molar ratio _{(MOH / ZrO 2 · xH 2} O) The method for producing an aqueous dispersion containing the chain silica-based fine particle group according to any one of claims 1 to 3, wherein the range is 1/1 to 10/1. In the step (a), the amount of hydrogen peroxide (H ₂ O ₂ ) added to the zirconium oxide hydrate (ZrO ₂ · xH ₂ O) is a molar ratio (H ₂ O ₂ / ZrO ₂ · xH). _The method for producing an aqueous dispersion containing chain silica-based fine particle groups according to any one of claims 1 to 4, wherein ₂ O) is in the range of 5/1 to 30/1. The chain silica according to any one of claims 1 to 5, wherein the aqueous solution prepared in the step (a) contains 0.3 to 5.0% by weight of a zirconium component on a ZrO ₂ conversion basis. A method for producing an aqueous dispersion containing fine particle groups. The chain silica-based fine particles according to any one of claims 1 to 6, wherein the silica sol used in the step (b) contains 0.5 to 5% by weight of a silicon component on the basis of SiO ₂ conversion. A method for producing an aqueous dispersion containing a group. The chain-like structure according to any one of claims 1 to 7, wherein the aqueous solution of the silicic acid solution added in the step (b) contains 0.5 to 5% by weight of a silicon component on the basis of SiO ₂ conversion. A method for producing an aqueous dispersion containing a group of silica-based fine particles. The addition amount of the aqueous solution containing the zirconium component in the step (b) is such that the zirconium component is represented by ZrO ₂ and the silicon component contained in the silica sol is represented by SiO ₂ with respect to the silica sol. The ratio (SiO ₂ / ZrO ₂ ) is in the range of 1/1 to 5/1, The production of an aqueous dispersion containing chain silica-based fine particle groups according to any one of claims 1 to 8 Method. In the step (b), with respect to the aqueous solution containing the zirconium component added at the same time, the silicon component contained in the silicic acid solution is represented by SiO ₂ and the zirconium component is represented by ZrO _2. when expressed in a molar ratio containing a chain silica fine particles group according to any one of claims 1 to 9, characterized in that in the range of 1 / 16-1 / 1 (ZrO ₂ / SiO ₂₎ A method for producing an aqueous dispersion.   11. The aqueous solution of silicic acid solution added in the step (b) is obtained by diluting water glass with water and then treating with a cation exchange resin to remove alkali. A method for producing an aqueous dispersion containing the chain silica-based fine particle group described above.   In the step (b), the silica sol is heated to a temperature of 70 to 95 ° C before adding the aqueous solution containing the zirconium component and the aqueous solution of the silicic acid solution. A method for producing an aqueous dispersion containing the chain silica-based fine particle group according to any one of the above.   The chain silica-based fine particle group according to claim 1, wherein the addition operation in the step (b) and the dealkalization operation in the step (c) are repeated a plurality of times. A method for producing an aqueous dispersion.   The chain silica system according to any one of claims 1 to 13, wherein the dealkalization operation in the step (c) is performed so that the pH of the aqueous solution is in a range of 7.0 to 10.0. A method for producing an aqueous dispersion containing fine particle groups.   The hydrothermal treatment in the step (d) is performed in an autoclave for 10 to 100 hours, and the aqueous dispersion containing chain silica-based fine particle groups according to any one of claims 1 to 14 is produced. Method.   The silica-based fine particles in which the chain silica-based fine particles are coated with a composite oxide composed of at least zirconium, silicon, and oxygen are coated with the silica-based fine particles or the band-shaped material of the composite oxide extending from the coating material. The method for producing an aqueous dispersion containing chain silica-based fine particle groups according to any one of claims 1 to 15, wherein a plurality of such shapes are connected via each other.   A plurality of silica-based fine particles coated with a composite oxide comprising at least zirconium, silicon and oxygen are connected via a coating material of the silica-based fine particles or a band-shaped material of the composite oxide extending from the coating material. An aqueous dispersion containing the chain silica-based fine particle group.   A silica-based fine particle coated with a composite oxide composed of at least zirconium, silicon and oxygen, obtained by subjecting the aqueous dispersion according to claim 17 to a solvent substitution step, a coating material for the silica-based fine particle or the coating An organic solvent dispersion containing a group of chain silica-based fine particles connected by a plurality of strips of the complex oxide extending from the material.