JP2002160907A - Spherical porous particle and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spherical porous particle which has a large particle size of 1 to 150 μm and is useful for a low refractive index material, an heat insulator, a cosmetic compounding ingredient or the like. SOLUTION: A first spherical porous particle, as a silica group layer is formed on its outer surface by which a material a fine particle of water molecule or the like is unable to penetrate into a ore interior, resulting in a low refractive index. A second spherical porous particle, as its silica group cover is compacted, is facilitated with a lower refractive indeed and a higher heat insulating effect. A third spherical porous particle, as its ore of the silica group layer is completely blocked by heating treatment d a solvent is absent in a space, has an extremely low refractive index and a high heat insulating effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a spherical porous particle in which an aggregate of inorganic oxide fine particles is covered with a silica-based layer, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, hollow silica particles having a particle size of about 0.1 to 300 .mu.m are known, and are disclosed in JP-A-6-330606.
Japanese Patent Application Laid-Open No. 7-113137 discloses that hollow particles containing a fragrance are used for a tatami mat, and Japanese Patent Application Laid-Open No. 7-01137 discloses that inorganic hollow particles containing liquid crystal are used for a liquid crystal display device. Also, Table 2000-500113
According to the publication, active silica is precipitated from an aqueous solution of an alkali metal silicate on a core made of a material other than silica, and the material is removed without breaking the silica shell, whereby hollow particles made of a dense silica shell are formed. Manufacturing methods are known. Further, JP-A-11-02931
According to Japanese Patent Publication No. 8, a core having a shell whose outer periphery is hollow and whose center is hollow, and whose shell has a dense gradient structure with a dense outer surface and a coarser inner surface.
Micron-sized spherical silica particles having a shell structure are known. However, in these inventions, the steps are complicated, the production cost of the particles is high, and the strength of the obtained particles is not sufficient, and therefore, the use is restricted. In addition, the present inventors have previously proposed that by completely covering the surface of the porous inorganic oxide fine particles with silica or the like, composite oxide fine particles having a low refractive index can be obtained (Japanese Patent Application Laid-Open (JP-A) No. Heisei 9 (1994) -207). 7-13
No. 3105). However, the particle size of the obtained particles is small, and there is also a restriction on the application.

[0003]

DISCLOSURE OF THE INVENTION The present invention has a particle size of 1
An object of the present invention is to provide spherical porous particles which are as large as 150 μm and are useful as a low refractive index material, a heat insulating material, a cosmetic compounding agent, an inorganic filler, a soundproofing material, a sound deadening material, and the like, and a method for producing the same.

[0004]

Means for Solving the Problems The spherical porous particles of the present invention are composed of an aggregate of inorganic oxide fine particles having an average particle diameter of 1 to 100 μm in which inorganic oxide fine particles having an average particle diameter of 2 to 250 nm are collected. And a silica-based layer covering the same. The pore volume of the inorganic oxide fine particle aggregate is preferably in the range of 0.01 to 0.8 cc / g. The thickness (T _s ) of the silica-based layer is 0.002 to 2
In the range of 5 μm, and the ratio (T _s ) / thickness (T _s ) of the silica-based layer to the average particle diameter (P _D ) of the spherical inorganic oxide particles
(P _D ) is preferably in the range of 0.002 to 0.25. It is preferable that the inorganic oxide fine particle aggregate contains a gel component derived from a hydrogel and / or xerogel of an inorganic oxide.

[0005] The method for producing spherical porous particles of the present invention is characterized by comprising the following steps (a) to (d). (A) a step of spraying a colloidal liquid of inorganic oxide fine particles or a colloidal liquid containing an inorganic oxide hydrogel and / or xerogel as required into an air stream to prepare an inorganic oxide fine particle aggregate; (C) dispersing the inorganic oxide fine particle aggregate in water and / or an organic solvent; and (d) dispersing the inorganic oxide fine particle aggregate. Adding an aqueous solution of an acid or an alkali and an organosilicon compound represented by the chemical formula (1) and / or a partial hydrolyzate thereof to cover the outer surface of the aggregate with a silica-based layer R _n Si (OR ') _4-n ··· (1) [However, R, R': hydrocarbon group such as alkyl group, aryl group, vinyl group, acrylic group, n = 0, 1, 2 or 3] Step (d) Spherical poly obtained in The dispersion of porous particles is 5 additional
It is preferable to perform a hydrothermal treatment at 0 to 350 ° C. Further, after separating the spherical porous particles from the dispersion of the spherical porous particles obtained by the step (d) or the hydrothermal treatment and drying,
The heat treatment is preferably performed at 400 to 1200 ° C. under atmospheric pressure or reduced pressure.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. The spherical porous particles of the present invention are obtained by coating an aggregate of inorganic oxide fine particles with a silica-based layer, and pores are formed in gaps between the inorganic oxide fine particles. The inorganic oxide fine particles need to have an average particle diameter in the range of 2 to 250 nm, but there are no other special restrictions, and conventionally known inorganic oxide fine particles can be used. Specific examples include fine particles of inorganic oxides such as silica, alumina, zirconia, titania, silica-alumina, silica-zirconia, silica-titania. Particularly, an oxide sol such as a silica sol disclosed in Japanese Patent Application Laid-Open No. 5-132309 filed by the applicant of the present application is preferable because it is a spherical inorganic oxide fine particle. Further, JP-A-10-4
The composite oxide fine particles containing an organic group disclosed in Japanese Patent No. 54043 can also be suitably used. Further, since the composite oxide sol disclosed in Japanese Patent Application Laid-Open No. Hei 7-133105 filed by the applicant of the present application is a particle having voids inside the particle, the spherical porous particle has a lower refractive index or excellent heat insulation. Is preferred because

The average particle diameter of the inorganic oxide fine particles is 2n.
If it is less than m, the particle diameter is too small, the pore volume due to the gap between the inorganic oxide fine particles is small (0.01 cc / g or less), and there is no difference from ordinary particles having a dense inside of the particles. It is difficult to obtain the efficiency and thermal insulation effect. If the average particle diameter exceeds 250 nm, the pore volume increases, but the bonding force between the fine particles is weak, and it is difficult to obtain an aggregate of inorganic oxide fine particles. Further, even if such an aggregate is obtained, the strength of the inorganic oxide fine particles is insufficient, so that it is difficult to form a silica-based coating layer described later. The preferred average particle diameter of the inorganic oxide fine particles is in the range of 5 to 100 nm. The average particle diameter of the aggregate of inorganic oxide fine particles is preferably in the range of 1 to 100 μm. If the average particle size exceeds 100 μm, the particle size distribution becomes non-uniform, and the shape of the particle is distorted and low in strength, which is not preferable. It is difficult to obtain an aggregate having an average particle diameter of less than 1 μm.

[0008] The aggregate of the inorganic oxide fine particles is 0.01 to
It has a pore volume in the range of 0.8 cc / g. If the pore volume is less than 0.01 cc / g, it is difficult to obtain the expected low refractive index effect and the expected heat insulating effect. The pore volume is 0.8c
If it exceeds c / g, the strength of the aggregate becomes insufficient, and it becomes difficult to form a silica-based coating layer. A preferred range of the pore volume is 0.05 to 0.75 cc / g. The pore volume can be determined by a nitrogen adsorption method (liquid nitrogen temperature, nitrogen adsorption amount at a relative pressure of 0.6). As a method for producing such an aggregate of inorganic oxide fine particles, a conventionally known method can be adopted, for example,
Examples include a microcapsule method, an emulsification method, an oil method, and a spray method. Above all, Japanese Patent Application 3-
No. 43201, Japanese Patent Publication No. 2-61406, etc., the production method of the spherical fine particle powder disclosed in the present invention provides a spherical inorganic oxide fine particle aggregate even when the starting inorganic oxide fine particles are not spherical. In addition, the manufacturing process is not complicated and the economy is excellent. This preferred manufacturing method will be described later.

Silica coating inorganic oxide fine particle aggregate
The system layer consists of a layer consisting of silica only (silica only layer) and a silica layer.
Silica (SiO)_Two)
Al _TwoO_Three, B_TwoO_Three, TiO_Two, ZrO_Two, Sn
O_Two, Ce_TwoO_Three, P_TwoO_Five, Sb_TwoO_Three, MoO_Three,
ZnO_Two, WO_ThreeOne or more inorganic oxides such as
And a coating layer comprising: As two or more inorganic oxides
Is TiO_Two-Al_TwoO_Three, TiO_Two-ZrO_TwoExample
Can be shown. At this time, silica and non-silica
The addition ratio of organic oxide is as follows:_Two, And
MO for inorganic oxides other than_XWeight ratio MO when expressed by
_X/ SiO_TwoIs preferably 0.2 or less. weight
Ratio MO_X/ SiO_TwoExceeds 0.2, a dense and uniform
It is difficult to form a cover layer. Including components other than silica
Heat resistance, weather resistance, chemical resistance, etc.
The folding rate can be adjusted. On the other hand, a silica single layer
A thin and uniform thickness within the range where the coalescence effect of coalescence can be obtained.
The coating layer can be easily formed. Note that this coating
The effect means that the intended spherical porous particles are
Can maintain voids and have low refractive index properties and / or
Means an effect capable of exhibiting heat insulation properties and the like.

The thickness (T _S ) of the silica-based layer is 0.00
It is preferably in the range of 2 to 25 μm, particularly 0.01 to 5 μm. When the thickness (T _S ) is less than 0.002 μm, it is difficult to form a coating layer capable of exhibiting the above-mentioned coating effect. That is, it is not preferable because a solvent or the like easily diffuses into the inside of the particles when used, and a low refractive index or a heat insulating effect may not be exhibited. If the thickness (T _s ) exceeds 25 μm, the coating layer is too thick with respect to the particle diameter of the spherical porous particles, the volume ratio of voids is low, and it is difficult to exhibit a low refractive index and a heat insulating effect. Therefore, the ratio (T _S ) / (P _D ) of the thickness (T _S ) of the silica-based layer to the average particle diameter (P _D ) of the spherical porous particles is 0.002 to 0.002.
It is preferably in the range of 0.25, especially 0.01 to 0.2. The thickness (T _s ) of the silica-based layer is determined by crushing spherical porous particles, and a transmission electron micrograph (TE
M) is photographed, the thickness of the coating layer portion is measured for 20 particles, and the average value can be obtained. The average particle diameter of the aggregate and the spherical porous particles is determined by a centrifugal sedimentation type particle size distribution analyzer (CAPA-70 manufactured by Horiba, Ltd.).
0).

The method of forming such a silica-based coating layer is as follows.
There is no particular limitation as long as a coating layer in the above range can be formed, but a predetermined amount of a silicate solution obtained by dealkalizing an alkali metal salt of silica (water glass) is added to a dispersion of an inorganic oxide fine particle aggregate described later. At the same time, a method of depositing a silicic acid solution on the outer surface of the aggregate by adding an alkali, or hydrolyzing a hydrolyzable organic silicon compound using an acid or an alkali catalyst, and causing the hydrolyzate on the outer surface of the aggregate The deposition method is preferable because a dense and uniform coating layer can be formed to such an extent that a solvent or the like can diffuse. Further, if necessary, a silica-based coating containing silica as a main component and an inorganic oxide other than silica by adding a precursor inorganic compound salt of the above-mentioned inorganic oxide other than silica together with a silicate solution or an organosilicon compound. Layers can be formed.

The above-mentioned inorganic oxide fine particle aggregate is preferably made of the above-mentioned inorganic oxide.
Neutralize or hydrolyze the precursor inorganic compound salt of oxide fine particles
Dried gel derived from hydrogel obtained by decomposition and
// xerogel (hereinafter sometimes referred to as gel component)
You. ) Is preferable. As these gel components
Is xenous silica obtained by gas phase pyrolysis of silicon tetrachloride.
It is obtained by hydrolyzing aerogels and silicates that are loggers.
Xe of silica obtained by heating and calcining silica hydrogel
Specific mention of white carbon, etc., which is a logger
Can be. The average particle diameter of the gel component is 10 to 500.
It is preferably in the range of nm. Average particle size 500
If it exceeds nm, the particle strength will decrease or the silica
When the average particle diameter is less than 10 nm,
The effect of increasing the voids in the aggregate is not sufficiently exhibited. gel
The mixing ratio of the components is such that the gel component is_G, And nothing
Oxide MO_SWeight ratio M when expressed by
O_G/ MO_SIs 5/95 to 90/10, especially 20/8
It is preferably in the range of 0 to 70/30. Weight ratio M
O_G/ MO _SIf less than 5/90, use gel component
The effect of increasing the voids becomes insufficient and the weight ratio MO_G/
MO_SExceeds 90/10, the particle strength decreases.
There is. In addition, the concentration of the colloid solution when the gel component is included
Similarly, 5 to 60% by weight in terms of oxide, particularly 10 to 5% by weight.
It is preferably in the range of 0% by weight.

Next, the method for producing spherical porous particles of the present invention will be described in the order of steps. Step (a) Preparation of Inorganic Oxide Fine Particle Aggregate The inorganic oxide fine particle aggregate is sprayed by spraying a colloidal solution of inorganic oxide fine particles or a colloidal solution containing the hydrogel and / or xerogel as needed into an air stream. Prepare. As the colloid liquid, a sol using water or an organic solvent of inorganic oxide fine particles such as silica, alumina, zirconia, titania, silica-alumina, silica-zirconia, silica-titania as a dispersion medium can be used. The concentration of the colloid solution is preferably in the range of 5 to 60% by weight, particularly 10 to 50% by weight in terms of oxide. If the concentration of the colloid liquid is less than 5% by weight, it is difficult to obtain an aggregate, and even if it is obtained, it is difficult to obtain large particles having a particle diameter in the range of 1 to 100 μm, which is not preferable. When the concentration of the colloid liquid exceeds 60% by weight, the colloid liquid becomes unstable, and it becomes difficult to obtain a spherical aggregate. Further, spray drying described later cannot be continuously performed, and the yield of the aggregate is reduced.

[0014] The method of spray-drying the colloid liquid includes the following.
There is no particular limitation as long as the above-mentioned aggregate is obtained, and a conventionally known method such as a rotating disk method, a pressure nozzle method, or a two-fluid nozzle method can be employed. In particular, Tokuhei 2-614
The two-fluid nozzle method disclosed in Japanese Patent Application Publication No. 06-2006 can obtain an inorganic oxide fine particle aggregate having a uniform particle size distribution,
Further, it is preferable because the average particle diameter can be easily controlled. The drying temperature at this time varies depending on the concentration of the colloid solution, the processing speed, and the like.
In particular, the temperature is preferably in the range of 50 to 120 ° C. If the drying temperature is less than 40 ° C., the drying becomes insufficient, and the colloidal liquid adheres to the wall of the spray drying device, and the yield tends to decrease,
If the drying temperature exceeds 150 ° C., the drying rate is too high, so that particles having apple-like depressions are obtained or donut-shaped particles, making it difficult to obtain true spherical aggregates.

Step (b) Heating the aggregate of inorganic oxide fine particles
The aggregate of inorganic oxide fine particles obtained in the treatment step (a) is subjected to a heat treatment in a temperature range of 150 to 600 ° C. in order to increase the bonding force between the inorganic oxide fine particles or the gel component. When the heat treatment temperature is lower than 150 ° C., the effect of improving the bonding force is not recognized. When the heat treatment temperature is higher than 600 ° C., the aggregate of the inorganic oxide fine particles may shrink, and the voids of the spherical porous particles finally obtained become small. Is not preferred.

Step (c) Dispersion of aggregate of inorganic oxide fine particles
Is dispersed in water and / or an organic solvent to prepare a dispersion of the aggregated inorganic oxide particles obtained in the preparation step (b). As the organic solvent, a monohydric alcohol such as ethanol, propanol, and butanol, a polyhydric alcohol such as ethylene glycol, and the like can be used. The concentration of the dispersion is preferably in the range of 0.1 to 40% by weight, particularly 0.5 to 20% by weight in terms of the concentration of the inorganic oxide fine particle aggregate converted to oxide. If the concentration is less than 0.1% by weight, in the step (d), the silica-based component also precipitates inside the aggregate of inorganic oxide fine particles, making it difficult to selectively precipitate on the outer surface. It is difficult to obtain spherical porous particles having a large particle size. On the other hand, if the concentration exceeds 40% by weight, the aggregates tend to aggregate in step (d), which is not preferable.

Step (d) In the step (d) of forming a silica-based coating layer , an acid or alkali aqueous solution is added to the above-mentioned aggregate dispersion and an organosilicon compound represented by the following chemical formula (1) and / or a partial hydrolyzate thereof. A decomposed product is added, and the outer surface of the aggregate is covered with a silica-based layer. R _n Si (OR ′) _4-n (1) [where R and R ′ are a hydrocarbon group such as an alkyl group, an aryl group, a vinyl group, and an acrylic group, n = 0, 1, 2, or 3] As such organosilicon compounds, specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, Dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, 3,3,3-trifluoropropyltrimethoxysilane , Methyl-3,3,3- Trifluoropropyldimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxytripropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane Γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyl Dimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β
(Aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, trimethylsilanol And methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane and the like.

When the spherical porous particles are used by being dispersed in an organic solvent or blended with an organic resin, the above-mentioned organosilicon compound having n of 1 to 3 and a fluorine-substituted alkyl group-containing compound must be used. Thereby, spherical porous particles having good dispersibility in an organic solvent and high affinity with an organic resin can be obtained. In addition, the compound in which n is 0 in the organosilicon compound can be used as it is, but the compound in which n is 1 to 3 has poor hydrophilicity, so that it can be uniformly mixed with the reaction system by being hydrolyzed in advance. Is preferable. For the hydrolysis, a well-known method for hydrolyzing these organosilicon compounds can be employed. When a basic catalyst such as an alkali metal hydroxide, aqueous ammonia, or an amine is used as the hydrolysis catalyst, these basic catalysts may be removed after the hydrolysis and used as an acidic solution. When a hydrolyzate is prepared using an acidic catalyst such as an organic acid or an inorganic acid, it is preferable to remove the acidic catalyst by ion exchange or the like after the hydrolysis. The obtained hydrolyzate of the organosilicon compound is desirably used in the form of an aqueous solution. Here, the aqueous solution means a state in which the hydrolyzate is not clouded as a gel but has transparency.

In addition to the above-mentioned organosilicon compound, a silicate solution obtained by alkali-removing an alkali metal salt of silica (water glass) can be used. When the dispersion medium of the aggregate particles is water alone or the ratio of water to the organic solvent is high, such a coating treatment with a silicate solution is also possible.
When a silicate solution is used, a predetermined amount of the silicate solution is added to the dispersion, and simultaneously an alkali is added to deposit the silicate solution on the outer surfaces of the aggregated particles. As the silicate solution, a silicate solution obtained by removing an alkali by treating an alkali silicate aqueous solution with a cation exchange resin or the like can be used. Particularly, the pH is _{2 to} 4, and the SiO ₂ concentration is about 7% by weight or less. Is preferable.

A silica metal comprising silica and an inorganic oxide other than silica by adding a precursor metal salt of the above-mentioned inorganic oxide other than silica together with the above-mentioned organosilicon compound and / or a partial hydrolyzate thereof or a silicic acid solution. Layers can also be formed. As a raw material of the inorganic oxide other than silica, it is preferable to use an alkali-soluble inorganic compound, and an alkali metal salt or an alkaline earth metal salt, an ammonium salt, or a quaternary ammonium salt of the above-mentioned metal or nonmetal oxo acid More specifically, sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, sodium phosphate and the like are suitable. is there.

The addition amount of the silica source and the silica source containing an inorganic compound salt other than silica is determined in consideration of the average particle diameter and the porosity of the inorganic oxide fine particle aggregate, and is determined by the above (T _S ).
/ (P _D ) is preferably in the range of 0.002 to 0.25, and the thickness (T _S ) of the silica-based layer is preferably in the range of 0.002 to 25 μm. For example, when the amount of oxide required to form a coating layer having a thickness of 2 μm on the outer surface of 100 g of the inorganic oxide fine particle aggregate having an average particle diameter of 100 μm and a pore volume of 0.3 cc / g is obtained by calculation, About 21 g of silica (or silica and an inorganic oxide other than silica) is obtained, and a corresponding silica source and an inorganic compound salt other than silica may be added. Here, since the content of the inorganic oxide other than silica was small, the calculation was performed on the assumption that the density of the coating layer was the same as that of silica (d = 2.2). Dispersion of the inorganic oxide fine particle aggregate coated with the silica-based layer,
It can be washed by a known washing method such as ultrafiltration. In this case, ultrafiltration may be carried out after previously removing a part of the alkali metal ion, alkaline earth metal ion, ammonium ion and the like in the dispersion with an ion exchange resin or the like. Next, the particles are separated from the dispersion by filtration and dried to obtain first spherical porous particles. Since the silica-based layer is formed on the outer surface of the spherical porous particles, only the fine particles such as water molecules do not enter the inside of the pores and have a low refractive index. That is, when the first spherical porous particles are used by being dispersed in a polymer compound such as an organic resin, the polymer compound does not enter the voids inside the particles through the pores of the silica-based layer. Since it is maintained, it has a low refractive index and a heat insulating effect.

Step (e) Hydrothermal treatment of the spherical porous particle dispersion
By subjecting the dispersion of the spherical porous particles obtained in the step (d) to hydrothermal treatment at a temperature range of 50 to 350 ° C. as desired, the silica-based layer covering the aggregate of inorganic oxide fine particles is densely packed. Can be That is, by reducing or eliminating the pores of the silica-based layer, the solvent and / or gas remains in the internal voids of the spherical porous particles. The hydrothermal treatment is performed by adding an aqueous alkali solution to the dispersion as needed, preferably adjusting the pH to a range of 8 to 13, and performing a heat treatment. The heat treatment temperature at this time is particularly preferably in the range of 100 to 300 ° C. At the time of the heat treatment, the concentration of the dispersion liquid may be previously diluted or concentrated. After that, the dispersion subjected to the hydrothermal treatment may be washed in the same manner as in the step (d). Finally, the particles are separated by filtration from the dispersion subjected to the hydrothermal treatment, dried and dried to form the second dispersion. Obtain spherical porous particles. In the spherical porous particles, since the silica-based coating layer is densified, the lowering of the refractive index and the heat insulating effect are promoted.

Step (f) Heat treatment of the spherical porous particles Further, the first spherical porous particles and the second spherical porous particles are optionally dried, and then dried under atmospheric pressure or reduced pressure at 400-1200. By performing heat treatment at a temperature of ° C., third spherical porous particles whose internal voids are sealed by the silica-based layer can be obtained. If the heat treatment temperature is lower than 400 ° C., the pores of the silica-based layer cannot be completely closed and densified. On the other hand, when the heat treatment temperature exceeds 1200 ° C., the spherical porous particles are easily fused to each other, and it is difficult to maintain the spherical shape. The third spherical porous particles have a very low refractive index because no solvent is present in the voids. Therefore, the coating obtained using these particles has a low refractive index, and the coated substrate has excellent antireflection performance. Further, a film in which these particles are laminated has an excellent heat insulating effect.

[0024]

According to the present invention, the average particle size is 2 to 25.
It is possible to obtain spherical porous particles having a structure in which an aggregate of fine inorganic oxide fine particles of 0 nm is covered with a silica-based layer. Since the spherical porous particles have a low refractive index and a heat insulating property, they are suitable as a heat insulating material, a sound deadening material, a sound insulating material and the like. In addition, if the spherical porous particles of the silica coating are used as a high-grade lubricating filler in cosmetics, a very light, soft and stretchable foundation can be obtained.
In addition, extenders for ink, toner, release improver,
Lubricants, abrasives such as wax for automobiles, high hardness fillers for improving abrasion resistance of resins and rubbers, fluidity improvers, matte fillers, non-shrinkage fillers, putty fillers, adsorbents, chromatographic carriers, and fragrances Uses such as comprehensive beads, fungicide / insecticide / fungicide-inclusive beads, liquid crystal inclusion beads and the like can also be exemplified. The method for producing spherical porous particles according to the present invention has simple steps and low production costs.

[0025]

The present invention will be described more specifically with reference to the following examples. Example 1 Silica sol (Cataloid S-20L, average particle size: 12 n, manufactured by Catalysis Chemical Industry Co., Ltd.)
m, concentration 20% by weight) 1000 g at a temperature of 105 ° C.
Of the two-fluid nozzle at a flow rate of 5 kg / hr and a gas pressure of 2 kg / hr at the other nozzle for spray drying. This powder was fired at 500 ° C. for 5 hours to obtain an inorganic oxide fine particle aggregate (A). The average particle diameter and the void ratio (pore volume) were measured, and the results are shown in Table 1. Next, 20 g of the aggregate (A) was dispersed in a mixed solvent obtained by adding 400 g of ammonia water having a concentration of 28% by weight to 1300 g of pure water and 1100 g of ethanol, and while maintaining the temperature of the dispersion at 35 ° C., the organic silicon was added thereto. As a compound, methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd .: KBE)
-13 and the SiO ₂ concentration of 34 wt%) 12 g was added in 12 minutes. Thereafter, the resultant was separated by filtration and dried to obtain spherical porous particles (A) coated with a methyl group-containing silica layer. The thickness, average particle diameter, void ratio (pore volume), and refractive index of the coating layer were measured, and the results are shown in Table 2.

Example 2 Silica sol (Cataloid SI-30, manufactured by Catalyst Chemical Industry Co., Ltd.)
Average particle diameter 12 nm, concentration 30% by weight) 1000 g,
Aerosil (manufactured by Nippon Aerosil Co., Ltd .: average particle size of 0.
05 μm), and water was added thereto to give a concentration of 2
A colloidal solution of 0% by weight of inorganic oxide fine particles was prepared, spray-dried and fired in the same manner as in Example 1 to obtain an inorganic oxide fine particle aggregate (B). Then, 1300 g of pure water,
20 g of the aggregate (B) was dispersed in a mixed solvent obtained by adding 400 g of aqueous ammonia having a concentration of 29% by weight to 1100 g of ethanol, and while maintaining the temperature of the dispersion at 35 ° C., tetraethoxysilane (organic silicon compound) was added thereto. 14 g of ethyl silicate-A (manufactured by Tama Chemical Industry Co., Ltd., SiO ₂ concentration: 28% by weight) was added over 14 minutes. Thereafter, the mixture was separated by filtration and dried to obtain spherical porous particles (B) covered with a silica layer.

Example 3 In the same manner as in Example 2, a dispersion liquid of the inorganic oxide fine particle aggregate (B) to which tetraethoxysilane was added was prepared. Next, this dispersion was filled in an autoclave,
For 10 hours, cooled, filtered, separated and dried to obtain spherical porous particles (C) on which a dense silica coating layer was formed.

Example 4 A part of the spherical porous particles (C) obtained in Example 3 was heated at 450 ° C.
For 3 hours to obtain spherical porous particles (D).

Example 5 In the same manner as in Example 3 except that the addition amount and the addition speed of tetraethoxysilane were changed to 70 g / 70 minutes, spherical porous particles having a silica coating layer formed thereon were prepared in the same manner as in Example 3. E) was obtained.

Example 6 Silica sol (Cataloid SI-50, manufactured by Catalysis Kasei Kogyo Co., Ltd., average particle diameter 25 n) was used as a colloid liquid of inorganic oxide fine particles.
m, concentration 50% by weight) 800 g and water 450 g are mixed,
Spray drying and firing were performed in the same manner as in Example 1 to obtain an inorganic oxide fine particle aggregate (F). Then, pure water 1300
20 g of aggregate (F) in a mixed solvent obtained by adding 400 g of 29% by weight ammonia water to 1100 g of ethanol and 1100 g of ethanol.
While maintaining the temperature of the dispersion at 35 ° C., and adding tetraethoxysilane (Tama Chemical Industry Co., Ltd .: ethyl silicate-A, SiO ₂ ) as an organosilicon compound.
14 g (concentration 28% by weight) were added in 14 minutes. Next, this dispersion was filled in an autoclave, subjected to a hydrothermal treatment at 180 ° C. for 10 hours, cooled, separated by filtration, and dried to obtain spherical porous particles (F) covered with a dense silica layer.

Example 7 Silica sol (Cataloid SI-50, manufactured by Catalyst Chemical Industry Co., Ltd.)
To 400 g of an average particle diameter of 25 nm and a concentration of 50% by weight, 60 g of water and 133 g of Aerosil (manufactured by Nippon Aerosil Co., Ltd .; average particle diameter of 0.05 μm) are added, and water is added to the resultant to add 20% by weight of inorganic substance. A colloidal solution of oxide fine particles was prepared, spray-dried and fired in the same manner as in Example 1 to obtain an inorganic oxide fine particle aggregate (G). Then, pure water 1
Aggregate (G) was added to a mixed solvent obtained by adding 400 g of 29% by weight aqueous ammonia to 300 g and 1100 g of ethanol.
While dispersing 20 g of the dispersion and maintaining the temperature of the dispersion at 35 ° C., tetraethoxysilane (manufactured by Tama Chemical Industry Co., Ltd .: ethyl silicate-A, S) was added thereto as an organosilicon compound.
14 g of an iO ₂ concentration of 28% by weight were added in 14 minutes.
Next, this dispersion was filled in an autoclave,
Hydrothermal treatment at 10 ° C. for 10 hours, cooling, filtration, separation, drying and spherical porous particles (G) covered with a dense silica layer
Got.

Example 8 Aqueous ammonia was added to metatitanic acid diluted to a concentration of 3% by weight to adjust the pH to 8, and the resulting precipitate was washed and desalted. 480 g of a quaternary amine (triethanolamine) was added to 1000 g of this precipitate (concentration as TiO ₂ of 10% by weight).
And heated at 95 ° C. for 1 hour to reduce the concentration of the dispersed particles to 2
A colloidal solution of titanium oxide having a weight percentage of 0% and an average particle diameter of 48 nm was obtained. This was spray-dried and fired in the same manner as in Example 1 to obtain an inorganic oxide fine particle aggregate (H). Then, a concentration of 29 was added to 1300 g of pure water and 1100 g of ethanol.
20 g of the aggregate (H) was dispersed in a mixed solvent to which 400 g of aqueous ammonia was added by weight, and while maintaining the temperature of the dispersion at 35 ° C., tetraethoxysilane (Tama Chemical Industry Co., Ltd.) was added thereto as an organosilicon compound. ): Ethyl silicate-A, SiO ₂ concentration 28% by weight) in 14 minutes. Next, this dispersion was filled in an autoclave, subjected to a hydrothermal treatment at 180 ° C. for 10 hours, cooled, separated by filtration, and dried to obtain spherical porous particles (H) covered with a dense silica layer.

Example 9 A 3% by weight aqueous solution of caustic soda was added to aluminum chloride diluted to a concentration of 2.5% by weight to adjust the pH to 7.5, and the resulting precipitate was washed and desalted. Nitric acid was added to the precipitate to peptize it to obtain a colloidal solution of alumina having a dispersed particle concentration of 10% by weight and an average particle diameter of 15 nm. This was spray-dried and fired in the same manner as in Example 1 to obtain an inorganic oxide fine particle aggregate (I). Then, pure water 1300
20 g of inorganic oxide particles (I) are dispersed in a mixed solvent obtained by adding 400 g of aqueous ammonia having a concentration of 29% by weight to 1100 g of ethanol, and while maintaining the temperature of the dispersion at 35 ° C., an organic silicon compound is added thereto. Tetraethoxysilane (manufactured by Tama Chemical Industry Co., Ltd .: ethyl silicate)
A, was added with SiO ₂ concentration of 28 wt%) 14 g 14 min. Next, this dispersion was filled in an autoclave,
After hydrothermal treatment at 180 ° C. for 10 hours, and after cooling, the mixture was separated by filtration and dried to obtain spherical porous particles (I) covered with a dense silica layer.

Comparative Example 1 The refractive index of the inorganic oxide fine particle aggregate (A) obtained in the middle step of Example 1 was measured, and the results are shown in Table 2.

Comparative Example 2 The refractive index of the aggregate (B) of inorganic oxide fine particles obtained in the middle of Example 2 was measured, and the results are shown in Table 2.

Comparative Example 3 Silica particles which are solid spheres obtained by hydrolyzing tetraethoxysilane (manufactured by Tama Chemical Industry Co., Ltd .: ethyl silicate-A) 5, average particle diameter 5 μm), the void ratio and the refractive index were measured, and the results are shown in Table 2.

[0037]

TABLE 1 Inorganic oxide concentration dry particle size volume of the particulate gel component dispersion mist average pore components mean blending ratio particle diameter MO _G / MO _S Temperature (nm) (wt%) ( ℃) (μm) (cc / g) Example 1 SiO ₂ 12 −20 105 5 0.3 Example 2 SiO ₂ 12 2/8 20 105 5 0.4 Example 3 SiO ₂ 12 2/8 20 105 5 0.4 Example 4 SiO ₂ 12 2/8 20 105 5 0.4 Example 5 SiO ₂ 12 2/8 20 105 5 0.4 Example 6 SiO ₂ 25−32 105 5 0.4 Example 7 SiO ₂ 25 4/6 20 105 5 0.7 Example 8 TiO ₂ 48−20 105 4.5 0.7 Example 9 Al ₂ O ₃ 15.4 −20 105 3.6 0.5 Comparative Example 1 SiO ₂ 12 −20 105 5 0.3 Comparative Example 2 SiO ₂ 12 2/8 20 105 5 0.4 Comparative Example 3 − − − − − − − −

[0038]

Table 2 Sphere-shaped multifilamentary porous particle child covering layer post-treatment average pore Ts / P _D refractive index particle component thickness Ts particle size P _D volumetric density (nm) (μm) (cc / g) (g / cc) Example 1 SiO ₂ 0.15 D 5.3 0.27 0.03 1.43 2.1 Example 2 SiO ₂ 0.10 D 5.2 0.35 0.02 1.41 2.0 Example 3 SiO ₂ 0.10 A / D 5.2 0 0.02 1.34 1.7 Example 4 SiO ₂ 0.10 A / C 5.2 0 0.02 1.34 1.7 Example 5 SiO ₂ 0.40 A / D 5.8 0 0.08 1.37 1.8 Example 6 SiO ₂ 0.10 A / D 5.2 0 0.02 1.34 1.7 Example 7 SiO ₂ 0.05 A / D 5.1 0 0.01 1.31 1.6 Example 8 SiO ₂ 0.15 A / D 4.8 0 0.03 2.21 2.9 Example 9 SiO ₂ 0.20 A / D 4.0 0 0.06 1.47 1.9 Comparative example 1 − − − 5 0.3 0 1.45 2.2 Comparative example 2 − − − 5 0.4 0 1.45 2.2 Comparative example 3 − − − 5 0 0 1.45 2.2 In the post-treatment column, A: hydrothermal treatment, C: baking treatment, D: drying treatment.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09C 3/06 C09C 3/06 4J002 // A61K 7/00 A61K 7/00 B 4J037 C08K 9/06 C08K 9 / 06 (72) Inventor Hiroyasu Nishida 13-2 Kitaminato-cho, Wakamatsu-ku, Kitakyushu-city, Fukuoka Prefecture Inside the Wakamatsu Plant of Kasei Kogyo Co., Ltd. (72) Inventor Hirokazu Tanaka 13-2 Kitaminato-cho, Wakamatsu-ku, Kitakyushu-shi, Fukuoka Catalyst Kasei F-term in the Wakamatsu Plant of Industrial Corporation (reference) DA02 DA16 DA30 4J002 AA011 DE096 DE136 DE146 DJ016 FB106 FD016 4J037 CB23 CC28 DD05 DD06 EE03 EE16 EE25 EE28 EE35 EE43 EE47 FF01

Claims (7)

[Claims] 1. A spherical porous body comprising an inorganic oxide fine particle aggregate having an average particle diameter of 1 to 100 μm in which inorganic oxide fine particles having an average particle diameter of 2 to 250 nm are collected, and a silica-based layer covering the same. Quality particles. 2. The spherical porous particles according to claim 1, wherein the pore volume of the aggregate of inorganic oxide fine particles is in the range of 0.01 to 0.8 cc / g. 3. The thickness (T) of the silica-based layer._S) Is 0.0
02 to 25 μm, and the thickness of the silica-based layer (T
_S) And the average particle diameter of the spherical inorganic oxide particles (P _D) Ratio
(T_S) / (P_D) Is in the range of 0.002 to 0.25
The spherical porous particles according to claim 1 or 2. 4. The spherical porous particles according to claim 1, wherein the inorganic oxide fine particle aggregate contains a gel component derived from a hydrogel and / or xerogel of an inorganic oxide. 5. The method for producing spherical porous particles according to claim 1, comprising the following steps (a) to (d). (A) a step of spraying a colloidal liquid of inorganic oxide fine particles or a colloidal liquid containing an inorganic oxide hydrogel and / or xerogel as required into an air stream to prepare an inorganic oxide fine particle aggregate; (C) dispersing the inorganic oxide fine particle aggregate in water and / or an organic solvent; and (d) dispersing the inorganic oxide fine particle aggregate. Adding an aqueous solution of an acid or an alkali and an organosilicon compound represented by the chemical formula (1) and / or a partial hydrolyzate thereof to cover the outer surface of the aggregate with a silica-based layer R _n Si (OR ') _4-n ... (1) [where R and R' are hydrocarbon groups such as alkyl group, aryl group, vinyl group and acrylic group, n = 0, 1, 2 or 3] 6. The method for producing spherical porous particles according to claim 5, further comprising the following step (e). (E) hydrothermally treating the dispersion of spherical porous particles obtained in step (d) at 50 to 350 ° C. 7. The method for producing spherical porous particles according to claim 5, further comprising the following step (f). (F) After the spherical porous particles are separated from the spherical porous particle dispersion and dried, 400 to 12 under atmospheric pressure or reduced pressure.
Step of heat treatment at 00 ° C