JP5698087B2 - Inorganic oxide powder - Google Patents

Description

  The present invention relates to a novel inorganic oxide powder. Specifically, it is composed of spherical inorganic oxide particles having a primary particle size with a small particle size obtained by a sol-gel method, has a small amount of metal impurities, and is in a dry state that can be crushed with a weak force. An inorganic oxide powder is provided.

  A sol-gel method is known as one type of method for producing inorganic oxide particles such as silica, titania, zirconia, and alumina. This production method is a method for obtaining inorganic oxide particles by hydrolysis and polycondensation reaction of a metal alkoxide such as tetraethoxysilane in an organic solvent containing water in the presence of an acid or a basic catalyst. The sol-gel method is characterized in that fine inorganic oxide particles having a relatively uniform particle size can be obtained, and the particles are used as fillers or abrasives for resins.

  In the presence of the above catalyst, inorganic oxide particles are highly dispersed as fine primary particles in the inorganic oxide particle dispersion obtained by hydrolysis and polycondensation reaction of metal alkoxide, that is, sol-gel method reaction. Therefore, it is very difficult to adopt filtration as a method for removing the dispersion medium from the dispersion and obtaining inorganic oxide particles. For this reason, as a method for obtaining the inorganic oxide particles, the dispersion is volatilized by heating or vacuum concentration, the dispersion medium is volatilized, the inorganic oxide particles are precipitated by a centrifugal separator, and then decantation is performed. The method of performing etc. is adopted. And the inorganic oxide particle of the dried state from which the dispersion medium was further removed is obtained by drying the wet body obtained by these methods.

  However, when the dispersion medium is removed from the inorganic oxide particle dispersion, an aggregate in which the inorganic oxide particles are aggregated with a strong force is generated. For this reason, even when the resulting inorganic oxide particles are crushed, inorganic oxide particles having a uniform particle size cannot be obtained, and when such inorganic oxide particles are dispersed in a resin or solvent, the aggregate However, there is a problem in that it is not easily crushed by the share of the disperser and is not uniformly dispersed in the resin or solvent. In particular, when fine inorganic oxide particles having a primary particle diameter of 1 μm or less are produced by a sol-gel method reaction, the particles have a strong agglomeration force, and agglomerates aggregated with an extremely strong force are generated. Tend.

  Various proposals have been made so far for solving such problems. For example, Patent Document 1 proposes a method in which inorganic oxide particles after drying the inorganic oxide particle dispersion are crushed by a jet mill. Although it is possible to obtain inorganic oxide particles having a certain particle size by this method, it is not possible to reduce aggregates aggregated by a strong force generated during the drying process, and it is fundamental to the above problem. It's hard to say a solution.

  The problem of aggregation in the dry state is more remarkable as the median diameter of the primary particles produced by the sol-gel method is smaller.

  Patent Document 2 also describes a method for preventing aggregation by adding ethylene glycol during the concentration of the dispersion medium as a method for solving the problem of aggregation and sintering of metal oxides without performing pulverization treatment. Has been. Although this method suppresses the formation of agglomerates that are difficult to disintegrate, depending on the drying and firing conditions, ethylene glycol may remain in the metal oxide. Was also difficult to apply.

JP-A-6-115925 JP 2003-277025 A

  Therefore, the object of the present invention is to disintegrate with a weak force when it is in a dry state even when spherical inorganic oxide particles having a primary particle size of a small particle size are generated by a sol-gel method. In addition, an object of the present invention is to provide an inorganic oxide powder with a small amount of impurities adhering to the particle surface.

  The present inventors have intensively studied to achieve the above object. As a result, in the presence of a catalyst, a metal salt is present as a coagulant in an inorganic oxide particle dispersion obtained by hydrolysis and polycondensation of metal alkoxide in an alcohol-water solvent, so-called sol-gel method. Then, an aggregate aggregated with the weak force of the inorganic oxide particles is generated in the dispersion, and the inorganic oxide powder obtained by filtering and drying such an aggregate has a weak force. It was confirmed that crushing was easy and the dispersibility when filling into a resin or the like was good.

However, when trying to obtain high-purity inorganic oxide powder, the cake of the inorganic oxide particle dispersion containing the above metal salt was washed with water, and the metal salt remaining in the cake was removed. It was found that when the aggregates of the inorganic oxide particles were broken and dried, a strong aggregate of the inorganic oxide particles was generated. Therefore, until obtaining an agglomerate of the inorganic oxide particles in the dry state, the presence of the metal salt is essential, metal salt has a problem called remained to a dry state. Therefore, for example, when inorganic oxide powder is used for applications such as for semiconductors, there is a concern about problems due to alkali metal salts such as sodium.

  As a result of further investigation based on the above findings, the presence of a specific salt having thermal decomposability as a coagulant in the inorganic oxide particle dispersion allows the action of the specific salt in the state of the dispersion. Thus, filtration can be performed while stably presenting aggregates aggregated by a weak force of the inorganic oxide particles, and such a salt is easily thermally decomposed during or after drying, and the particle surface In addition, it is possible to obtain a high-purity inorganic oxide powder that does not contain a metal salt, and the inorganic oxide powder can be crushed with a weak force in a dry state despite the absence of the salt. The present invention has been found to be obtained in such a state, and the present invention has been completed.

That is, the present invention is an inorganic oxide powder comprising spherical inorganic oxide particles containing silica having a median diameter of 0.01 to 5 μm obtained by a sol-gel method and having a water content of 3 to 15% by mass. In the inorganic oxide powder, the metal salt does not exist on the particle surface, and the inorganic oxide powder is mixed with 50 ml of a lab run screw tube bottle manufactured by AS ONE Co., Ltd. (trade name: mouth inner diameter 20.3 mm). , Total length 35 mm), 0.08 g is added, and 40 g of pure water is added to adjust the measurement solution. As an ultrasonic disperser, SONIFIRE250 (trade name) manufactured by BRABSON is used. .5mm, immersed 3cm from the tip of the tap horn of the full-length 7 cm, frequency 20 kHz, an ultrasonic dispersion aqueous dispersion obtained by performing 4 minutes at output 50 W, the laser diffraction scattering method That is one peak maximum of the grain size measurement is and inorganic oxide powder which volume frequency of particles of diameter more than 10 times the median diameter is equal to or less than 0.1%.

  The inorganic oxide powder of the present invention is an inorganic powder obtained by drying despite being spherical oxide particles having a median diameter of 0.01 to 5 μm and a small particle diameter obtained by a sol-gel method. Oxide powder can be easily crushed with a weak force, and it can be easily broken by the share of the disperser when it is dispersed in a resin or solvent, and the particle size is uniform in the resin or solvent. It is possible to uniformly disperse in the form of primary particles.

  Moreover, the inorganic oxide powder of the present invention is free from impurities such as metal salts on the particle surface, has high purity, and does not need to be subjected to impurity removal treatment.

The inorganic oxide powder of the present invention comprises spherical inorganic oxide particles obtained by a sol-gel method, and has the properties of a dry powder having a water content of 3 to 15 mass .

In addition, the said moisture content can be controlled with the drying temperature after filtration in the below-mentioned manufacturing method. For example, when the drying temperature is 35 to 250 ° C., the amount of water contained in the inorganic oxide powder is 3 to 15% by mass. When further baking is performed at 600 to 1300 ° C. after drying, the amount of water contained in the inorganic oxide powder can be 1% by mass or less. For example, when using the inorganic oxide powder as an external additive for toner, to maintain the toner charge stability, it is necessary that the moisture of about 3 to 15 wt% of the inorganic oxide particles are present . Moreover, in the filler for sealing materials, such as a semiconductor, in order to prevent the crack which generate | occur | produces when soldering, it is necessary to reduce the moisture content as much as possible. The inorganic oxide powder of the present invention can be used by appropriately adjusting the amount of water depending on the application.

  Examples of the inorganic oxide include Group 4 metals of the periodic table such as titanium, zirconium and hafnium, Group 13 metals of the periodic table such as boron, aluminum, gallium and indium, and Group 14 metals of the periodic table such as germanium and tin. Examples thereof include metal oxides, silica (silicon oxide), and composite inorganic oxides composed of these elements.

  Among the above-mentioned inorganic oxides, silicon, titanium, zirconium, aluminum oxides, and composite inorganic oxides composed of these elements are preferable, especially silica and composite inorganic oxides composed of silicon-containing elements, In particular, silica is preferable because the effects of the present invention remarkably appear.

  The primary particles of the inorganic oxide particles forming the inorganic oxide powder of the present invention have a median diameter of 0.01 to 5 μm, particularly 0.01 to 1 μm. The inorganic oxide particles having such a small particle size have a strong cohesive force, and the particles having such a small particle size have the characteristics described below, which is the greatest feature of the inorganic oxide particles of the present invention.

  That is, the inorganic oxide powder of the present invention has the following characteristics while having a median diameter in the above range.

(1) The inorganic oxide powder has no metal salt on the particle surface,
(2) The aqueous dispersion of the inorganic oxide powder has one peak maximum in particle size measurement by laser diffraction scattering, and the volume frequency of particles having a diameter of 10 times or more the median diameter is 0. That is, the inorganic oxide particles of the present invention are heated in filtration, drying, etc. by using a specific salt as a coagulant as described later. Thus, the salt can be decomposed and removed, so that the particle surface is substantially free of metal salts except for unavoidable contamination due to adsorption of metal salts present in the air. For example, when the inorganic oxide powder is silica powder, the total content of the metal salt present on the particle surface is 10 ppm or less, particularly 5 ppm or less in terms of metal element, as shown in Examples described later. Is possible. Moreover, about a specific metal, sodium content is 2 ppm or less, Preferably it is 1 ppm or less, Iron content is 1 ppm or less, Preferably, it is 0.5 ppm or less, More preferably, it is 0.1 ppm or less. Therefore, the inorganic oxide powder of the present invention can be suitably used in semiconductor applications where metal impurities are hated.

  In addition, regarding the characteristics of (2), the inorganic oxide particles of the present invention have a laser for the aqueous dispersion of the inorganic oxide powder due to the presence of the salt during filtration and drying after the sol-gel reaction. The particle size measurement by the diffraction scattering method has one peak maximum, and the volume frequency of particles having a diameter of 10 times or more of the median diameter has an extremely good crushing characteristic of 0.1% or less.

  The method for preparing the aqueous dispersion is carried out by adding 40 g of pure water to 0.08 g of the inorganic oxide powder, and ultrasonically dispersing for 16 minutes at a frequency of 20 kHz and an output of 50 W. Specifically, first, 0.08 g of inorganic oxide powder is added to 50 ml of a lab run screw tube bottle manufactured by AS ONE Co., Ltd. (trade name: mouth inner diameter 20.3 mm, total length 35 mm), and 40 g of pure water is further added. The measurement solution. For ultrasonic dispersion, a SONIFIRE 250 (trade name) manufactured by BRABSON is used, and 3 cm from the tip of a tap horn having a tip diameter of 12.5 mm and a total length of 7 cm is immersed in the measurement solution, and the frequency is 20 kHz and the output is 50 W for over 16 minutes. Perform sonic dispersion.

  Then, the particle size of the slurry adjusted by the above method is measured by a laser diffraction scattering method in the range of 0.04 to 2000 μm, and based on this, a particle size distribution curve is created. The feature (2) of the inorganic oxide powder of the present invention has one peak maximum value in the particle size distribution curve. This indicates that there is no remaining secondary agglomerated particles that are easily dispersed to the primary particles by the light energy applied to the inorganic oxide powder in the preparation of the dispersion.

  Further, the volume frequency of particles having a diameter of 10 times or more of the median diameter being 0.1% or less indicates that they do not contain hugely grown particles.

  The inorganic oxide powder obtained by the sol-gel method and having the median diameter has the characteristics shown in the above (1) and (2) for the first time provided by the present invention.

  In addition, the inorganic oxide powder of the present invention is also characterized by a narrow particle size distribution width produced by a sol-gel method. As for the particle size distribution width of the inorganic oxide powder, the coefficient of variation, which is one of the indicators showing the spread of the particle size distribution width, is usually 40% or less, preferably 35% or less, more preferably 30% or less.

  The method for producing the inorganic oxide powder of the present invention employs a sol-gel method. The sol-gel method is a method in which metal alkoxide is hydrolyzed and polycondensed in an alcohol-water solvent in the presence of a catalyst to produce inorganic oxide particles. It is possible to obtain spherical inorganic oxide particles.

  The metal alkoxide used in producing the inorganic oxide of the present invention is not particularly limited as long as it is a known compound used for producing inorganic oxide particles by a sol-gel method reaction, and is produced. Depending on the type, it may be used as appropriate.

  Examples of the metal alkoxide used as a raw material for producing the inorganic oxide powder of the present invention include titanium tetraisopropoxide, titanium tetra n-butoxide, zirconium n-butoxide, zirconium t-butoxide, trimethyl borate, and boric acid. Triethyl, aluminum n-butoxide, aluminum isopropoxide, indium (III) isopropoxide, germanium (IV) isopropoxide, germanium (IV) methoxide, tin (IV) butoxide, methyltrimethoxysilane, methyltriethoxysilane, Examples thereof include metal alkoxides such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane.

  Among the above metal alkoxides, titanium tetraisopropoxide, titanium tetra n-butoxide, zirconium n-butoxide, aluminum n-butoxide, aluminum isopropoxide, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetra Ethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane are preferable, and titanium tetraisopropoxide, zirconium n-butoxide, tetramethoxysilane, and tetraethoxysilane are industrially easily available and easy to handle. It is especially preferable from the point.

  Specific examples of the metal alkoxide used for obtaining a composite oxide with an inorganic oxide obtained from the metal alkoxide include lithium ethoxide, sodium methoxide, sodium isopropoxide, potassium methoxide, magnesium isopropoxide. , Calcium ethoxide, strontium isopropoxide, barium isopropoxide, ytterbium (III) isopropoxide, lanthanum (III) ethoxide, titanium tetraisopropoxide, titanium tetra n-butoxide, zirconium n-butoxide, zirconium t-butoxide , Trimethyl borate, triethyl borate, aluminum n-butoxide, aluminum isopropoxide, indium (III) isopropoxide, germanium (IV) isopropoxy De, germanium (IV) methoxide, tin (IV) butoxide, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, metal alkoxides such as tetrabutoxysilane and the like.

  In the production method of the present invention, the metal alkoxide may be used alone or in combination of two or more. When using two or more types, it is possible to obtain a composite inorganic oxide containing silica by using a mixture of alkoxysilane containing silicon and metal alkoxide other than alkoxysilane. is there. It is also possible to carry out hydrolysis and polycondensation of metal alkoxide after hydrolysis and polycondensation of alkoxysilane. In such a case, a composite inorganic oxide in which a metal oxide is bonded to the surface of silica is obtained. be able to.

  Further, when the metal alkoxide is a liquid at normal temperature and pressure, it can be used as it is, or it can be diluted with an organic solvent. When the metal alkoxide is solid at normal temperature and pressure, it may be used after being dissolved or dispersed in an organic solvent.

  As the catalyst used in the sol-gel reaction, a known catalyst used for producing an inorganic oxide by a sol-gel method reaction can be employed. Among these catalysts, it is preferable to use a basic catalyst in order to obtain an inorganic oxide powder formed by the spherical inorganic oxide particles of the present invention.

Examples of the basic catalyst include amines and alkali metal hydroxides. In particular, it is preferable to use amines from the viewpoint that the amount of metal impurities other than the metal forming the target inorganic oxide particles is small and high-purity inorganic oxide particles can be obtained. If Specific examples of the amines include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine emissions, and the like. Among these, it is particularly preferable to use ammonia because of its high volatility and the high reaction rate of the sol-gel method. In addition, the said basic catalyst can be used individually or can also use 2 or more types.

  In addition, as the basic catalyst, an industrially available catalyst can be used as it is, or it can be diluted with water or an organic solvent such as ammonia water. In particular, it is preferable to dilute the basic catalyst in water, adjust the concentration as appropriate, and use it as an aqueous solution because it is easy to control the progress of the reaction. In the case of using an aqueous solution as the basic catalyst, it is preferable to use an aqueous solution having a catalyst concentration in the range of 1 to 30% by mass from the viewpoint of industrial availability or easy concentration adjustment. .

  What is necessary is just to determine the usage-amount of a basic catalyst suitably considering the hydrolysis of a metal alkoxide, the polycondensation reaction rate, etc. Usually, it is sufficient that the content of the basic catalyst is 0.1 to 60% by mass, more preferably 0.5 to 40% by mass, based on the mass of the metal alkoxide used.

  Moreover, an acidic catalyst can be used conveniently as a catalyst of the preliminary hydrolysis reaction of the metal alkoxide mentioned later. Specific examples include hydrogen chloride, sulfuric acid, nitric acid, and acetic acid.

  As with the basic catalyst, the acidic catalyst can be used as it is, or can be diluted with a solvent such as water.

  The amount of the acidic catalyst used may be appropriately determined in consideration of the hydrolysis and polycondensation reaction rate of the metal alkoxide. Usually, it is sufficient to use in the range of 0.00001 to 10% by mass, more preferably 0.0001 to 1% by mass, based on the mass of the metal alkoxide used.

  In addition, water is essential for the reaction of the sol-gel method. Therefore, when not using a catalyst as aqueous solution, it is necessary to add water required for the said reaction. The amount of water used may be appropriately adjusted according to the particle size of the inorganic oxide particles to be produced. However, if the amount is too small, the reaction rate of the sol-gel method is slow, and if it is too large, it takes a long time for drying. Therefore, the amount of the inorganic oxide particle dispersion obtained by the reaction of the sol-gel method is usually small. 2 to 50% by mass, more preferably 5 to 40% by mass.

  In order to obtain the inorganic oxide powder excellent in dispersibility of the present invention, it is preferable to use a mixed solvent of water and alcohols as a reaction solvent. Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, butanol and the like. Depending on the type of alcohol used, the reaction rate and the particle size of the resulting inorganic oxide particles also change, so that they may be appropriately adjusted and selected for use. In particular, methanol, ethanol, and isopropyl alcohol are preferably used from the viewpoint that they can be easily removed by drying.

  Alcohols can be used alone or in admixture of two or more. In addition, the amount of alcohol used may be appropriately determined according to the particle diameter of the target inorganic oxide particles and the concentration of the inorganic oxide particles in the inorganic oxide particle dispersion after the sol-gel method reaction. Good. For example, it is sufficient to use it in a range of 10 to 90% by mass, more preferably 15 to 80% by mass with respect to the mass of the inorganic oxide particle dispersion obtained by a sol-gel method reaction.

  The reaction of the sol-gel method for obtaining the inorganic oxide powder of the present invention proceeds in the presence of the catalyst. The contact method between the metal alkoxide and the catalyst is not particularly limited, and may be appropriately determined in consideration of the configuration and scale of the reaction apparatus.

  Specifically, a method in which alcohols and water are charged into a reaction vessel, and a metal alkoxide and a catalyst, or an aqueous solution of the catalyst (hereinafter, the catalyst or an aqueous solution of the catalyst is simply referred to as a catalyst), respectively, And a method of adding a metal alkoxide to the reaction vessel, or a method of adding an alcohol and a catalyst to a reaction vessel and adding the metal alkoxide and the catalyst simultaneously. Among these methods, a method in which an alcohol and a catalyst are charged into a reaction vessel and a metal alkoxide and a catalyst are added simultaneously is preferable from the viewpoint of good reaction efficiency. In this case, for example, after adding a part of the metal alkoxide first, the remaining metal alkoxide and the catalyst can be added simultaneously.

  When two or more kinds of metal alkoxides are used, they can be mixed and added simultaneously, or each can be added sequentially. In particular, when producing a composite inorganic oxide containing silica, it is possible to perform preliminary hydrolysis and use it as a composite metal alkoxide. For example, by reacting alkoxysilane in methanol under hydrochloric acid catalyst, it can be hydrolyzed with acid, and by adding metal alkoxide other than alkoxysilane such as titanium tetraisopropoxide, adjustment is possible. is there.

  Further, it is more preferable that the metal alkoxide and the catalyst are added dropwise in the liquid. Dropping in the liquid means that the tip of the dropping port is immersed in the reaction liquid when the raw material is dropped in the reaction liquid. The position of the tip of the dropping port is not particularly limited as long as it is in the liquid, but a position where stirring is sufficiently performed such as in the vicinity of the stirring blade is desirable.

  The addition time of the metal alkoxide and the catalyst is a very important factor in adjusting particles having a narrow particle size distribution width, and the particle size distribution width tends to be widened as the addition time is shortened. Moreover, even if it is too long, particle growth is not stably performed. Therefore, when obtaining inorganic oxide particles having a narrow particle size distribution width and uniform particle size, the addition time is preferably in the range of 0.5 to 15 hours in consideration of the concentration of the catalyst and the like.

  The reaction temperature is not particularly limited as long as the reaction of the sol-gel method proceeds promptly, and may be appropriately adjusted according to the particle size of the inorganic oxide particles forming the target inorganic oxide powder. good. In general, the lower the reaction temperature, the larger the particle size of the obtained inorganic oxide particles. When obtaining inorganic oxide particles having a median diameter of 0.01 to 5 μm, the reaction temperature may be appropriately selected within the range of −10 to 60 ° C.

  In order to advance the reaction of the sol-gel method with certainty, it is possible to ripen the reaction after the dropping of the metal alkoxide or the catalyst is completed. In this case, the aging temperature is preferably in the same range as the reaction temperature, that is, −10 to 60 ° C., and the aging time may be 0.25 to 5 hours.

  In the method of the present invention, in order to obtain inorganic oxide particles having a desired particle size, after aging, a metal alkoxide and a catalyst are added again to grow the particle size of the inorganic oxide particles. Also good.

  The concentration of the inorganic oxide particles in the inorganic oxide particle dispersion obtained by the reaction of the sol-gel method increases the viscosity of the dispersion when the amount of the inorganic oxide particles contained in the dispersion is large. Therefore, it is difficult to handle, and if it is too small, the amount of inorganic oxide particles obtained by one reaction is reduced, which is uneconomical. Therefore, the concentration of the inorganic oxide particles in the inorganic oxide particle dispersion obtained by the reaction of the sol-gel method is adjusted to 1 to 40% by mass, particularly 2 to 25% by mass, more preferably 15 to 25% by mass. It is preferable to do. The concentration of the inorganic oxide particles in the dispersion is adjusted by adjusting the amount of the alcohols and water used so that the concentration of the inorganic oxide particles after the reaction is within a predetermined range. It is also possible to adjust the concentration of the inorganic oxide particles in the dispersion by adding the alcohol or water after the reaction.

  The inorganic oxide particle powder of the present invention can be thermally decomposed into the inorganic oxide particle dispersion obtained by the reaction of the sol-gel method at a relatively low temperature, preferably at a temperature of 100 ° C. or lower. It can be obtained by filtering the dispersion in a state where it is present as a coagulant comprising a specific salt having a property (hereinafter also referred to as a specific coagulant). The aspect in which the specific coagulant is present in the dispersion is not particularly limited, and the salt may be added to the inorganic oxide particle dispersion or applied in the inorganic oxide particle dispersion. A compound that forms a salt may be added. Specifically, as a compound that forms such a salt in the inorganic oxide particle dispersion, carbon dioxide may be mentioned. That is, when the basic catalyst used for the reaction of the sol-gel method is ammonia such as aqueous ammonia, by adding carbon dioxide to the inorganic oxide particle dispersion obtained by the reaction of the sol-gel method, A salt is formed by the reaction, and the salt can be present in the dispersion as a specific coagulant. Also, it is preferable to use solid carbon dioxide, that is, dry ice because carbon dioxide is easy to handle and the residence time in the dispersion is longer.

  On the other hand, examples of the salt added to the inorganic oxide particle dispersion include ammonium carbonate, ammonium hydrogen carbonate, and ammonium carbamate. These can be used alone or in combination of two or more. The commercially available “ammonium carbonate” is generally a mixture of ammonium hydrogen carbonate and ammonium carbamate, and can be used as it is.

  In the method for producing an inorganic oxide powder of the present invention, an agglomerate aggregated with a weak force of inorganic oxide particles is formed in the dispersion by allowing the specific coagulant to be present in the dispersion. Such agglomerates can be stably present even in the presence of a dispersion medium due to the presence of a specific coagulant, and prevent the formation of agglomerated aggregates due to the strong force of inorganic oxide particles during drying, which will be described later. Is possible. In the production method described above, the specific coagulant has an unknown mechanism of action, but it is possible to achieve the effect as long as it exists at least up to the stage of filtering the inorganic oxide particle dispersion.

  The usage rate of the specific coagulant can be set as follows according to the type of the specific coagulant used. The proportion of the specific coagulant used is determined by taking into account the balance between the degree of formation of aggregates in which the inorganic oxide particles in the dispersion medium aggregate with a weak force and the waste of using an unreasonably large amount of raw material. Is set. The mass of the inorganic oxide particles as a standard of the use ratio of the specific coagulant in the following is a conversion value when it is assumed that all the metal alkoxide used is hydrolyzed and polycondensed to form inorganic oxide particles. .

  When using the above-mentioned carbon dioxide to make the specific coagulant present, the use ratio is 0.005 parts by mass or more with respect to 100 parts by mass of the inorganic oxide particles contained in the dispersion medium, Furthermore, it is preferable to set it as 0.05 mass part or more, It is especially preferable to set it as 0.05-300 mass part, and it is especially preferable to set it as 0.25-200 mass part.

  When adding and using ammonium carbonate, ammonium hydrogen carbonate, or ammonium carbamate as the specific coagulant, the use ratio is 0 with respect to 100 parts by mass of the inorganic oxide particles contained in the dispersion. 0.001 part by mass or more, further preferably 0.001 to 80 parts by mass, particularly preferably 0.001 to 15 parts by mass, and particularly preferably 0.001 to 10 parts by mass.

  As the pH of the inorganic oxide particle dispersion when the specific coagulant is present, the salt derived from the specific coagulant does not cause undesirable decomposition in the dispersion, and the pH at which the effects of the present invention can be effectively exhibited. It is desirable to select and install the area. From such a viewpoint, the pH of the dispersion is preferably in the basic region, more preferably 9 or more. In particular, when ammonia such as aqueous ammonia is used as a catalyst for the reaction in the sol-gel method, the pH of the inorganic oxide particle dispersion after the reaction is usually 9 or more, and the inorganic oxide particle dispersion after the reaction Thus, it is preferable to allow the specific coagulant to exist without adjusting the pH.

  The temperature at which the specific coagulant is present in the inorganic oxide particle dispersion obtained by the reaction of the sol-gel method can stably present an aggregate in which the generated inorganic oxide particles are aggregated with a weak force. The temperature is not particularly limited and may be set as appropriate. In consideration of the decomposition temperature of the specific coagulant, etc., it is usually −10 to 60 ° C., preferably 10 to 40 ° C., the same as the reaction temperature.

  In addition, the time from the presence of the specific coagulant to the concentration of the dispersion by filtration or the like is not particularly limited, and may be appropriately determined in consideration of working conditions and the like, and is usually 0.25 to 72. It is sufficient to appropriately determine the time, preferably in the range of 1 to 48 hours.

  As described above, the inorganic oxide powder of the present invention can be used for filtering the inorganic oxide particle dispersion, in which the aggregate is formed by the weak force of the inorganic oxide particles, such as vacuum filtration, pressure filtration, and centrifugal filtration. By doing so, it can be efficiently taken out as a cake. The filter paper, filter, filter cloth, and the like used for filtration are not particularly limited as long as they are industrially available, and may be appropriately selected according to the scale of the separation device. Inorganic oxide particles having a median diameter of 0.01 to 5 μm, a pore diameter of about 5 μm is sufficient. Moreover, it is also possible to carry out by overlapping filter papers, filters, filter cloths, and the like.

  The inorganic oxide particle cake after the filtration is dried to obtain the inorganic oxide powder having the target moisture content. The drying method is not particularly limited as long as the dispersion medium remaining in the cake can be removed, and can be performed by a known drying method such as reduced pressure drying or blow drying.

  The temperature at the time of drying is not particularly limited as long as the dispersion medium (alcohol and water) can be removed, and may be appropriately determined in consideration of the degree of pressure reduction at the time of drying. Drying at 35 to 250 ° C., more preferably 50 to 250 ° C., is preferable because the salt derived from the specific coagulant can be removed along with the removal of the dispersion medium. In addition, when drying is performed at a temperature lower than the above temperature, the specific coagulant is removed from the inorganic oxide particles by thermal decomposition by heating to a temperature equal to or higher than the thermal decomposition temperature of the specific coagulant after removing the dispersion medium. Is possible. Note that it is sufficient to finish the drying until no change in the weight of the inorganic oxide particles occurs.

  By the drying, the dispersion medium present on the surface of the inorganic oxide particles is removed, and it is usually possible to obtain inorganic oxide particles having a dispersion medium content of 15% by mass or less. Here, the remaining dispersion medium is usually water.

  The above-described drying treatment removes the dispersion medium on the surface of the inorganic oxide particles, does not produce an agglomerate that is highly pure and difficult to disintegrate, has excellent dispersibility, and is a fine inorganic oxide with a uniform particle size It is possible to obtain an inorganic oxide powder formed from the particles. The crushing strength of such an inorganic oxide powder is as low as about 0.2 N as described in the examples described later, and when dispersed in a resin or solvent without performing a special crushing treatment. It is possible to disperse easily and uniformly disperse in the state of primary particles having a uniform particle size in the resin or solvent.

  In addition, the inorganic oxide powder is subjected to surface treatment with a known surface treatment agent such as silicone oil, silane coupling agent, silazane, titanate coupling agent, aluminum coupling agent, etc. It is also possible to use it. Of these, silicone oil, silane coupling agent, and silazane are particularly preferably used.

  As the silicone oil used in the present invention, known silicone oils usually used for surface treatment can be used without particular limitation, and are appropriately selected according to the performance of the surface-treated inorganic oxide powder required. And use it. Specifically, dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen silicone oil, alkyl modified silicone oil, amino modified silicone oil, epoxy modified silicone oil, carboxyl modified silicone oil, carbinol modified silicone oil, methacryl modified Examples thereof include silicone oil, polyether-modified silicone oil, and fluorine-modified silicone oil. Among these, dimethyl silicone oil is preferably used for the purpose of simply hydrophobizing.

  The amount used when using the silicone oil is not particularly limited, but if it is too small, the surface treatment becomes insufficient, and if it is too much, the post-treatment becomes complicated. Therefore, with respect to 100 parts by mass of the inorganic oxide powder to be used, It is good to set it as 0.05-30 mass parts, More preferably, it is 0.1-20 mass parts.

  As the silane coupling agent used in the present invention, a known silane coupling agent that is usually used for surface treatment can be used without particular limitation, and the performance of the surface-treated inorganic oxide powder that is required, etc. It may be appropriately selected and used accordingly. Specifically, methyltrimethoxysilane, methyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxytrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyl Triethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N-phenyl-3- Mino trimethoxysilane, N, N-dimethyl-3-aminopropyltrimethoxysilane, N, N-diethyl-3-aminopropyltrimethoxysilane, 4-styryl trimethoxysilane and the like. Of these, methyltrimethoxysilane, methyltriethoxysilane, hexyltrimethoxysilane, and decyltrimethoxysilane are preferably used for the purpose of simply hydrophobizing.

  The amount used when using the silane coupling agent is not particularly limited, but if it is too small, the surface treatment becomes insufficient, and if it is too large, the post-treatment becomes complicated, so that 100 parts by mass of the inorganic oxide powder to be used is used. On the other hand, it is good to set it as 0.05-40 mass parts, More preferably, it is 0.1-20 mass parts.

  As the silazane used in the present invention, a known silazane usually used for surface treatment can be used without particular limitation. Among silazanes, hexamethylsilazane is preferably used because of its particularly good reactivity and ease of handling.

  The amount used when using silazane is not particularly limited, but if it is too small, the surface treatment becomes insufficient, and if it is too large, the post-treatment becomes complicated. Therefore, with respect to 100 parts by mass of the inorganic oxide powder to be used, It is good to set it as 0.05-60 mass parts, More preferably, it is 0.1-50 mass parts.

  These surface treatment agents may be used alone or in combination of two or more.

  The surface-treated inorganic oxide powder thus obtained is hydrophobized with an M value (hydrophobicity) described later of 50% or more, and a crushing strength value of 0.1 or less. It is lower than this, and it is excellent in crushability. The use of the surface-treated inorganic oxide powder of the present invention is very useful when it is necessary to improve the familiarity with the resin, or to prevent the viscosity from being increased when kneaded into the resin.

  As described above, the water absorbed in the inorganic oxide powder after drying is 15% by mass or less, but it is not completely removed, so the amount of water in the powder needs to be further reduced Performs a further baking treatment.

  If the calcination temperature during the calcination treatment is too low, it is difficult to remove the dispersion medium component, and if it is too high, the inorganic oxide particles are fused, so that the calcination temperature is 300 to 1300 ° C. Is preferred.

  The firing time is not particularly limited as long as the remaining water is removed, but it is uneconomical if it is too long, so after raising the temperature to the intended firing temperature, 0.5 to 48 hours, more preferably, It is sufficient to hold and calcinate in the range of 2 to 24 hours.

  The atmosphere during firing is not particularly limited, and can be performed under an inert gas such as argon or nitrogen, or in an air atmosphere.

  The inorganic oxide powder obtained in this way has a water content of 1% by mass or less and is excellent in dispersibility, so that it can be suitably used in applications that dislike water such as fillers for sealing materials.

  The inorganic oxide powder obtained after the baking treatment can be used for various applications without performing a crushing treatment, but is used after being crushed by a known crushing means depending on the purpose. It is also possible. Moreover, it is also possible to surface-treat with well-known surface treatment agents, such as silicone oil, a silane coupling agent, a silazane, a titanate coupling agent, an aluminum coupling agent, and to use it for the intended use.

  The surface treatment agent and the surface treatment method may be performed in the same manner as described above, and the M value (hydrophobicity) of the obtained surface-treated inorganic oxide powder is hydrophobized to 50% or more. The water content is also 1% by mass or less.

  EXAMPLES Hereinafter, examples and comparative examples will be shown in order to specifically describe the present invention, but the present invention is not limited only to these examples. The measuring method of various physical properties in the present invention is as follows.

<Measurement of median diameter of inorganic oxide particles in dispersion>
Measurement of the median diameter of the inorganic oxide particles in the dispersion was performed by an image analysis method using a scanning electron microscope (hereinafter referred to as SEM). The dispersion obtained after completion of the sol-gel reaction was diluted with pure water and dropped onto a silicon wafer. Then, the dispersion medium was removed by drying under reduced pressure for 2 hours or more at room temperature to prepare a sample for SEM observation. In addition, observation of the inorganic oxide particle which exists in the produced sample was carried out 200 or more times, changing the imaging | photography place suitably. Moreover, the value was described in terms of volume.

<Distribution method>
0.08 g of inorganic oxide powder is put into 50 ml of Laboran screw tube bottle (trade name: mouth inner diameter 20.3 mm, total length 35 mm) manufactured by AS ONE Co., Ltd., and 40 g of pure water is further added to obtain a measurement solution. For ultrasonic dispersion, SONIFIRE250 (trade name) manufactured by BRABSON is used, and 3 cm from the tip of a tap horn with a tip diameter of 12.5 mm and a total length of 7 cm is immersed in the above measuring solution, and ultrasonic dispersion is performed at a frequency of 20 kHz and an output of 50 W. Carried out. The inorganic oxide powder obtained after drying was dispersed for 4 minutes, the inorganic oxide powder obtained after firing was dispersed for 16 minutes, the particle size was measured by the laser diffraction scattering method described later, and the number of peak maximum values The volume frequency of particles having a diameter 10 times or more the median diameter was measured. The total volume frequency of particles having a diameter of 10 times or more the median diameter was defined as the amount of aggregate.

<Measurement of median diameter and coefficient of variation of inorganic oxide particles after drying and firing>
The median diameter and coefficient of variation of the dispersion obtained by the dispersion method described above are in the range of 0.04 μm to 2000 μm by measuring the polarization scattering intensity difference using a Beckman Coulter LS230 (trade name) manufactured by Beckman Coulter Inc. Measured with The coefficient of variation was calculated from the following formula. The smaller the variation coefficient, the narrower the particle size distribution width.

Coefficient of variation (%) = standard deviation of particle diameter (μm) / number average value of particle diameter (μm)
<Measurement of crushing strength>
In order to unify the measurement conditions of Examples and Comparative Examples described later, measurement was performed by the following method. The dispersion after the sol-gel reaction was centrifuged to separate the dispersion medium and the inorganic oxide particles. Thereafter, the inorganic oxide powder obtained after vacuum drying at 100 ° C. was passed through a sieve having an aperture of 1.4 mm and subsequently 0.71 mm, and the inorganic oxide powder remaining on the sieve having an aperture of 0.71 mm was measured. Used for.

  The inorganic oxide powder was placed on an upper pan balance, loaded with a metal spatula, and the load when the powder was crushed was measured. The measurement was performed 50 times, and the average value for 40 times excluding the upper and lower values was taken as the crushing strength value. A smaller value indicates that the particles are more easily crushed.

<Measurement of M value (hydrophobicity)>
0.2 g of the surface-treated inorganic oxide particles were added to 50 ml of water in a 250 ml beaker and stirred with a magnetic stirrer. To this, methanol was added using a burette, and titration was performed with the end point when the total amount of the sample powder was wetted and suspended in the solvent in the beaker. At this time, the tube was introduced into the solution with a tube so that the sample did not directly touch the sample. The volume% of methanol in the methanol-water mixed solvent at the end point was defined as M value.

<Moisture content measuring method>
The inorganic oxide powder was conditioned at a temperature of 25 ° C. and a humidity of 60% for 24 hours. About 2 g of the sample after conditioning was weighed and heated at 120 ° C. for 24 hours. The loss on heating was divided by the sample weight before heating (about 2 g), and the percentage was taken as the amount of water.

<Measuring method of metal element component amount>
2 g of the dried inorganic oxide powder was precisely weighed and transferred to a platinum dish, and 10 ml of concentrated nitric acid and 10 ml of hydrofluoric acid were added in this order. This was placed on a hot plate set at 200 ° C. and heated to dry the contents. After cooling to room temperature, 2 mL of concentrated nitric acid was further added, and the solution was placed on a hot plate set at 200 ° C. and heated to dissolve. After cooling to room temperature, the solution as the contents of the platinum dish was transferred to a 50 mL volumetric flask, diluted with ultrapure water, and aligned with the marked line . Using this as a sample, the amount of metal element components was measured with an ICP emission analyzer (manufactured by Shimadzu Corporation, model number “ICPS-1000IV”).

<Measurement of nitrogen content>
High sensitivity N.M. Using C analyzer NC-22F, 50 mg of silica particles are weighed on a board, completely oxidized at 830 ° C., and then subjected to quantitative analysis of nitrogen components by TCD gas chromatography, whereby nitrogen in inorganic oxide particles Content (mass%) was measured.

Example 1
In a 5 L four-necked flask, 150 g of 15% ammonia water as a basic catalyst (1.2% by mass with respect to the mass of the metal alkoxide) and 1040 g of methanol as an organic solvent (mass of the inorganic oxide particle dispersion) 27 mass%) was added and stirred at 35 ° C. 1940 g of tetramethoxysilane as the metal alkoxide, 700 g of 5% by weight ammonia water as the basic catalyst (1.8% by weight as the ammonia content with respect to the weight of the metal alkoxide, and 3.0% by weight in total with the previously added ammonia water) ) Were independently dropped into the liquid. The dropping was carried out by adjusting the speed so as to be completed in 5 hours. At 10 minutes after the start of dropping, the reaction solution was cloudy, and it was confirmed that the reaction was progressing. The mass of the inorganic oxide particle dispersion is 3830 g.

  After completion of the dropwise addition, aging was performed for 0.5 hour, and 20 g of dry ice (solid carbon dioxide) (2.6% by mass with respect to the inorganic oxide particles in the dispersion) was added and left for 20 hours. Silica particles were settled after 20 hours had passed. Using quantitative filter paper (retained particle diameter: 7 μm), vacuum filtration was performed to obtain 1303 g of cake. The filtrate was transparent and no filtration leakage was confirmed. Furthermore, it dried under reduced pressure at 100 degreeC for 16 hours, and obtained 804 g of silica particles. Subsequently, baking was performed at 900 ° C. for 10 hours. The firing atmosphere was not particularly adjusted, and was performed in an air atmosphere. There was no appearance of sintering after firing, and 743 g of silica particles were obtained.

Example 2
The operation was carried out in the same manner as in Example 1 except that 20 g of ammonium hydrogen carbonate (2.6% by mass with respect to the inorganic oxide particles in the dispersion) was added instead of dry ice.

Example 3
The same procedure as in Example 1 was performed except that the amount of dry ice added was changed to 200 g (26 mass% with respect to the inorganic oxide particles in the dispersion).

Example 4
The same procedure as in Example 1 was performed except that filtration was performed 2 hours after the addition of dry ice.

Example 5
The operation was performed in the same manner as in Example 1 except that the reaction temperature was changed to 15 ° C.

Example 6
In a 5 L four-necked flask, 210 g of 25% by mass aqueous ammonia as a basic aqueous solution (3.1% by mass as the ammonia content with respect to the mass of the metal alkoxide), 310 g of methanol as the organic solvent, and isopropyl alcohol 710 g (26.8% by mass relative to the mass of the inorganic oxide particle dispersion) was added and stirred at 40 ° C. After 26 g of tetraethoxysilane was added dropwise as a metal alkoxide, the reaction solution became cloudy after 10 minutes had passed, confirming that the reaction had proceeded. Subsequently, a mixed solution of 1650 g of tetramethoxysilane and 170 g of methanol (4.5% by mass with respect to the mass of the inorganic oxide particle dispersion, 31% by mass in total of alcohol) as the metal alkoxide, and 25% as the basic catalyst Ammonia water 730 g (10.9% by mass as the ammonia content with respect to the mass of the metal alkoxide, and 14% by mass in total with the ammonia water previously charged) was dropped in the liquid independently. The dropping was carried out by adjusting the speed so as to be completed in 2 hours. The mass of the inorganic oxide particle dispersion is 3806 g.

  After completion of dropping, 20 g of dry ice (solid carbon dioxide) (3.0% by mass with respect to the inorganic oxide particles in the dispersion) was added and left for 20 hours. After 20 hours, silica particles had settled, and a quantitative filter paper (retained particle diameter: 7 μm) was used, followed by vacuum filtration to obtain 1266 g of cake. The filtrate was transparent and no filtration leakage was confirmed. Furthermore, it vacuum-dried at 100 degreeC for 16 hours, and obtained 693 g of silica particles. Subsequently, baking was performed at 900 ° C. for 10 hours. The firing atmosphere was not particularly adjusted, and was performed in an air atmosphere. There was no appearance of sintering after firing, and 659 g of silica particles were obtained.

Example 7
The operation was performed in the same manner as in Example 6 except that filter paper (pore diameter: 6 μm) was used and pressure filtration was performed at a pressure of 0.1 MPa.

Example 8
The same operation as in Example 6 was performed, except that filter cloth (aeration rate 0.2 cc / (cm ² · sec)) and filter paper (pore diameter 6 μm) were used in piles and centrifugal filtration was performed at a rotation speed of 1000 rpm. It was.

Example 9
A 3 L four-necked flask was charged with 475 g of tetramethoxysilane as a metal alkoxide, 238 g of methanol as an organic solvent (11% by mass with respect to the mass of the inorganic oxide particle dispersion), and 0.035% by mass as an acid catalyst. Hydrochloric acid was hydrolyzed by adding 56 g of hydrochloric acid (0.003% by mass as the content of hydrogen chloride with respect to the mass of the metal alkoxide) and stirring at room temperature for 10 minutes. Subsequently, a solution obtained by diluting 250 g of titanium tetraisopropoxide as a metal alkoxide with 500 g of isopropyl alcohol (23 mass% with respect to the mass of the inorganic oxide particle dispersion) was added to obtain a transparent composite alkoxide solution.

  In a 5 L four-necked flask, 256 g of isopropyl alcohol (12 mass% with respect to the mass of the inorganic oxide particle dispersion, 46 mass% in total), 64 g of 25 mass% aqueous ammonia (based on the mass of the metal alkoxide, The ammonia content was 2.2% by mass), and the mixture was kept at 40 ° C. and stirred. The composite alkoxide solution and 344 g of 25% by mass aqueous ammonia (3.9% by mass as the ammonia content with respect to the mass of the metal alkoxide, 6% by mass in total) were independently added dropwise to the solution. The dropping was carried out by adjusting the speed so as to be completed in 5 hours. At 10 minutes after the start of dropping, the reaction solution was cloudy, and it was confirmed that the reaction was progressing. The mass of the inorganic oxide particle dispersion is 2183 g.

  After completion of the dropwise addition, aging was performed for 0.5 hour, and 150 g of dry ice (solid carbon dioxide) (58% by mass with respect to the inorganic oxide particles in the dispersion) was added and left for 4 hours. Silica-titania composite oxide particles settled when left standing for 4 hours. Using quantitative filter paper (retained particle diameter: 5 μm), vacuum filtration was performed to obtain 398 g of cake. The filtrate was transparent and no filtration leakage was confirmed. The obtained silica-titania composite oxide particles were vacuum-dried at 100 ° C. for 16 hours to obtain 260 g of silica-titania composite oxide. Further, baking was performed at 1050 ° C. for 12 hours. The firing atmosphere was not particularly adjusted, and was performed in an air atmosphere. There was no appearance of sintering after firing, and 247 g of silica-titania composite oxide particles were obtained.

Example 10
In a 3 L four-necked flask, 4.0 g of 0.1 mass% hydrochloric acid as the acid catalyst (0.001 mass% as the content of hydrogen chloride with respect to the mass of the metal alkoxide), 158 g of tetraethoxysilane as the metal alkoxide, methanol 950 g (24% by mass with respect to the mass of the inorganic oxide particle dispersion) was added, and hydrolysis was performed while stirring at room temperature for 2 hours. A mixed solution of 38 g of zirconium n-butoxide and 400 g of isopropanol (10% by mass with respect to the mass of the inorganic oxide particle dispersion) was added thereto as a metal alkoxide to obtain a composite alkoxide solution.

  To a 10 L four-necked flask, 1980 g of methanol (51 mass% with respect to the mass of the inorganic oxide particle dispersion) and 125 g of 25 mass% aqueous ammonia (9.5 mass% with respect to the mass of the metal alkoxide) were added. Then, as a metal alkoxide, a mixed solution of 4.0 g of tetraethoxysilane and 80 g of methanol (2% by mass with respect to the mass of the inorganic oxide particle dispersion) was maintained at 20 ° C. and added over 5 minutes. It was confirmed that the reaction solution was slightly cloudy. The said composite alkoxide solution was dripped there over 2 hours. Furthermore, a mixed solution of 128 g of tetraethoxysilane and 400 g of methanol (1% by mass with respect to the mass of the inorganic oxide particle dispersion, and 88% by mass in total) as a metal alkoxide was dropped over 2 hours. The mass of the inorganic oxide particle dispersion is 4267 g.

  After completion of the dropwise addition, the mixture was aged for 0.5 hours, and 20 g of dry ice (solid carbon dioxide) (21% by mass with respect to the inorganic oxide particles in the dispersion) was added and left for 20 hours. Silica-zirconia composite oxide particles settled when left standing for 20 hours. Using quantitative filter paper (retained particle diameter 5 μm), vacuum filtration was performed to obtain 153 g of cake. The obtained silica-zirconia composite oxide particles were vacuum-dried at 100 ° C. for 16 hours to obtain 98 g of silica-zirconia composite oxide. Further, baking was performed at 1000 ° C. for 6 hours. The firing atmosphere was not particularly adjusted, and was performed in an air atmosphere. There was no appearance of sintering after firing, and 89 g of silica-zirconia composite oxide particles were obtained.

Example 11
The operation was performed in the same manner as in Example 1 except that 780 g of methanol and 260 g of isopropyl alcohol were used as the organic solvent.

Example 12
The operation was performed in the same manner as in Example 1 except that 20 g of ammonium carbonate (2.6% by mass with respect to the inorganic oxide particles in the dispersion) was added instead of dry ice.

Example 13
The operation was performed in the same manner as in Example 1 except that 20 g of ammonium carbamate (2.6% by mass with respect to the inorganic oxide particles in the dispersion) was added instead of dry ice.

Example 14
The operation was performed in the same manner as in Example 1 except that the drying temperature was 150 ° C. The nitrogen content was measured and found to be 0.01%.

Example 15
The operation was performed in the same manner as in Example 2 except that the drying temperature was 150 ° C. The nitrogen content was measured and found to be 0.01%.

Example 16
The operation was carried out in the same manner as in Example 1 except that 110 g of ammonium hydrogen carbonate (15% by mass with respect to the inorganic oxide particles in the dispersion) was added.

Example 17
The operation was performed in the same manner as in Example 1 except that 370 g of ammonium hydrogen carbonate (50% by mass with respect to the inorganic oxide particles in the dispersion) was added.

Comparative Example 1
In Example 1, when filtration was performed without adding dry ice, the dispersion slipped through the filter paper and silica could not be recovered. The obtained dispersion was vacuum-dried at room temperature and a certain amount of the dispersion medium was distilled off, followed by drying and firing in the same manner as in Example 1.

Comparative Example 2
To 3830 g of the inorganic oxide particle dispersion obtained in Example 1, 3830 g of pure water was added and concentrated under reduced pressure at 40 ° C., and 3830 g of methanol water was distilled off. Further, after adding 1530 g of pure water, 1530 g of methanol water was distilled off to obtain an inorganic oxide particle dispersion in which the dispersion medium was replaced with water. After 110 g of ammonium hydrogen carbonate (15% by mass with respect to the inorganic oxide particles in the dispersion) was added to the obtained inorganic oxide particle dispersion, the same operation as in Example 1 was performed. Since methanol was not present in the dispersion medium, the dispersion liquid slipped through the filter paper during filtration under reduced pressure, and silica particles could not be recovered.

Comparative Example 3
The operation was performed in the same manner as in Comparative Example 2 except that 370 g of ammonium hydrogen carbonate (50% by mass with respect to the inorganic oxide particles in the dispersion) was added.

  In the said Examples 1-17 and Comparative Examples 1-3, the median diameter of the inorganic oxide particle in an inorganic oxide dispersion liquid, the median diameter of the inorganic oxide particle after drying, and a baking, a coefficient of variation, and drying The results of the crushing strength of the later inorganic oxide particles are shown in Table 1. From the results in Table 1, the inorganic oxide particles obtained by the production method of the present invention all have very low crushing strength, and are crushed in the concentration of the inorganic oxide particle dispersion and the drying after the concentration. It can be seen that formation of strong agglomerates of inorganic oxide particles, which is necessary for the above, is prevented.

Example 18
400 g of the silica particles obtained after drying at 100 ° C. for 16 hours obtained in Example 1 were put in a container with a volume of 20 L, purged with nitrogen, and simultaneously heated to 250 ° C. After the nitrogen flow was continued for 15 minutes at a rate of 10 L / min, the inside of the container was sealed, and water vapor was introduced at a partial pressure in the mixer of 60 kPa. Subsequently, 120 g of hexamethyldisilazane (30 parts by mass with respect to the inorganic oxide particles) was sprayed with a one-fluid nozzle, and the surface treatment was performed by continuing stirring for 60 minutes. After opening the mixer and replacing the atmosphere with nitrogen gas, the surface-treated product was taken out.

Example 19
Using 400 g of the silica particles obtained in Example 11, surface treatment was performed in the same manner as in Example 18 .

Example 20
140 g of silica particles obtained in Example 11 and 700 g of toluene were placed in a 1 L four-necked flask and stirred at room temperature. Thereto was added 1.68 g of amino-modified oil (1.2 parts with respect to the inorganic oxide particles), and the mixture was heated to reflux at 110 ° C. for 1 hour. Thereafter, the solvent was distilled off under reduced pressure to obtain a surface-treated product.

Example 21
140 g of silica particles obtained in Example 11 and 700 g of toluene were placed in a 1 L four-necked flask and stirred at room temperature. Thereto, 3.76 g of decyltrimethoxysilane (2.7 parts relative to the inorganic oxide particles) was added, and the mixture was heated to reflux at 110 ° C. for 1 hour. Thereafter, the solvent was distilled off under reduced pressure to obtain a surface-treated product.

  Regarding Examples 18 to 21, the values of hydrophobicity and crushing strength before and after drying were shown. The surface was hydrophobized. Moreover, the value of the crushing strength was lowered by the surface treatment.

Claims (3)

An inorganic oxide powder comprising spherical inorganic oxide particles containing silica having a median diameter of 0.01 to 5 μm, obtained by a sol-gel method, and having a moisture content of 3 to 15% by mass , the inorganic In the oxide powder, no metal salt is present on the particle surface, and the inorganic oxide powder is placed in 50 ml of a lab run screw tube bottle (product name: mouth inner diameter 20.3 mm, total length 35 mm) manufactured by AS ONE Corporation. 0.08 g was added, 40 g of pure water was added to adjust the measurement liquid, and a BRABSON SONIFIRE 250 (trade name) was used as an ultrasonic disperser. The measurement liquid had a tip diameter of 12.5 mm and a total length of 7 cm. immersed 3cm from the tip of the tap horn, frequency 20 kHz, an ultrasonic dispersion aqueous dispersion obtained by performing 4 minutes at output 50 W, peak in the particle size measured by a laser diffraction scattering method Maximum value is one, and the inorganic oxide powder volume frequency of particles of diameter more than 10 times the median diameter is equal to or less than 0.1%. The inorganic oxide powder according to claim 1 , which has been hydrophobized and has an M value of 50% or more. The filler for sealing agents containing the inorganic oxide powder of Claim 1 or 2 .