JP5148971B2 - Spherical silica particles and method for producing the same - Google Patents

Description

  The present invention relates to spherical silica particles comprising an aggregate of a large number of hollow silica fine particles and a method for producing the same.

  Particles formed by aggregating a large number of fine particles can impart useful properties such as heat insulation, low refractive index, weight reduction, etc. to materials, and many studies on such particles and their production methods have been made. .

  A technique for preparing an aggregate of fine particles by spray-drying oxide fine particles is known. For example, Patent Document 1 (Japanese Patent Laid-Open No. Sho 61-270201) includes primary particles having an average particle diameter of 250 nm or less. A technique for preparing inorganic oxide particles having an average particle diameter of 1 to 20 μm by spray drying a colloidal solution is disclosed.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2002-160907), an average particle diameter is 2 to 250 nm by further coating an oxide layer on a fine particle aggregate obtained by spray drying a colloidal solution. Spherical porous particles comprising an aggregate of inorganic oxide fine particles having an average particle diameter of 1 to 100 μm in which inorganic oxide fine particles are collected and an oxide-based layer covering the aggregate are disclosed.

  It is known to mix oxide fine particles as a filler in a thermosetting resin for a semiconductor encapsulant. For example, Patent Document 3 (Japanese Patent Application Laid-Open No. 2002-37620) discloses an aggregate of non-fusing and non-aggregating true spherical oxide particles having a fusing rate of 0.1% or less, and having an average particle size. An invention relating to a true spherical oxide particle aggregate characterized by 0.6 to 6 μm, a particle size distribution width of 0.3 to 10 μm and a particle size distribution dispersity (CV value) of 10% or more is described. As a semiconductor sealing material, there is a description that it is added to a resin and used.

Moreover, in patent document 4 (Unexamined-Japanese-Patent No. 2001-220296), in the epoxy resin composition containing an epoxy resin, a hardening | curing agent, and an inorganic filler, a specific surface area is 6-200 m < ² > / g as an inorganic filler, An invention relating to an epoxy resin composition comprising a porous oxide having a true specific gravity of 2.0 to 2.2 and an average particle diameter of 2 to 50 μm is disclosed.

  Patent Document 5 (Japanese Patent Laid-Open No. 2006-335881) discloses a dispersion liquid in which aggregate particles composed of aggregates of primary fine particles of hollow silica contain hollow silica dispersed in a dispersion medium, The average aggregate particle diameter of the aggregate particles is in the range of 60 to 400 nm, and the average aggregate particle diameter is in the range of 1.5 times or more the average primary particle diameter of the silica. An invention relating to a dispersion containing hollow silica is described.

Aggregate particles composed of aggregates of such primary particles of hollow silica are expected to have particularly large heat insulation and light weight effects.
However, in the dispersion containing hollow silica described in Patent Document 5, the aggregate particles are dispersed in a dispersion medium, and when only the aggregate particles are separated by means such as drying, It has been known that aggregate particles have a strong tendency to agglomerate and become indefinite, and therefore have a non-uniform particle size.

For this reason, there has been a demand for spherical silica particles that can be used as components of light aggregates, ink-receiving layers, and the like, and are composed of spherical hollow silica fine particles and in a monodispersed state with respect to particle size distribution. .
JP-A 61-270201 JP 2002-160907 A JP 2002-37620 A Japanese Patent Laid-Open No. 2001-220696 JP 2006-335881 A

  The present invention provides a spherical silica particle that is useful as a light aggregate, a component of an ink receiving layer, and the like, is spherical, has a high monodispersity in particle size distribution, and has a high void ratio, and a method for producing the same. It is the purpose.

To achieve the above object, the present invention is as follows.
[1] A hollow silica fine particle aggregate having an average particle diameter in the range of 5 to 300 nm, a specific surface area in the range of 50 to 1500 m ² / g, and hollow silica fine particles having a hollow structure assembled and bound. Spherical silica particles having an average particle diameter of 1 μm to 50 μm.
[2] The spherical silica particles according to [1], wherein the bulk specific gravity (CBD) is in the range of 0.7 to 1.0 g / ml.
[3] A hollow silica fine particle aggregate having an average particle diameter in the range of 5 to 300 nm, a specific surface area in the range of 50 to 1500 m ² / g, and hollow silica fine particles having a hollow structure assembled and bound. Spherical silica particles having an average particle diameter of 1 μm to 50 μm and having a bulk specific gravity (CBD) in the range of 0.7 to 1.0 g / ml and a particle breaking strength in the range of 0.5 to 100 Kgf / mm ² . Spherical silica particles characterized by the above.
[4] The spherical silica particles according to any one of [1] to [3], wherein the hollow silica fine particles have a monodispersed particle size distribution.
[5] The production of spherical silica particles according to any one of [1] to [4], wherein a hollow silica fine particle aggregate is prepared by spraying a spray liquid containing a hollow silica fine particle dispersion in an air stream Method.
[6] The method for producing spherical silica particles according to [5], comprising the following steps.
(A): A step of spraying a spray liquid containing a hollow silica fine particle dispersion in an air stream to prepare a hollow silica fine particle aggregate (B): The temperature of the hollow silica fine particle aggregate obtained in the step (A) Step (C1) of heat treatment in the range of 150 to 600 ° C .: Following the step (B), the hollow silica fine particle aggregate is dispersed in water and / or an organic solvent to prepare a hollow silica fine particle aggregate dispersion. Step (D): Following the step (C 1 ), spherical silica particles are separated from the hollow silica fine particle aggregate dispersion, dried, and then heated at 400 to 1200 ° C. under atmospheric pressure or reduced pressure. Process to process

[7] Subsequent to the step (C1), the following step (C2) or (C3), or after the step (C2) and after the step (C3), the step (D) is performed. production process [6], wherein the spherical boss silica particles, which comprises carrying out.
(C2): A step of surface-treating the hollow silica fine particle aggregate by adding the following i), ii) or iii) to the dispersion of the hollow silica fine particle aggregate prepared in the step (C1)
i) Acid or alkali
ii) Acid or alkali and an organosilicon compound represented by the following general formula and / or a partial hydrolyzate thereof General formula: R _n Si (OR ′) _4-n
[However, R and R 'is an alkyl group having 1 to 18 carbon atoms, the number 6-18 aryl group carbon atoms or a group Ru is selected from vinyl or acrylic group, n represents 0, 1, 2 or 3 It is an integer. ]
iii) Silicic acid solution and alkali (C3): Hydrothermal treatment of the hollow silica fine particle aggregate dispersion at 50 to 350 ° C.
[8] The method for producing spherical silica particles according to [6] or [7], wherein the spray liquid in the step (A) further contains a silicic acid liquid.
[9] The method for producing spherical silica particles according to any one of [6] to [8], wherein the hollow silica fine particle dispersion in the step (A) is in a monodispersed state.

  Since the spherical silica particles according to the present invention are hollow silica particles having an average particle diameter of 1 to 50 μm, the bulk specific gravity can be in the range of 0.7 to 1.0 g / ml. Is also spherical and has high monodispersity. Such spherical silica particles can be produced by the production method according to the present invention. The spherical silica particles according to the present invention can be suitably used for a lightweight aggregate, a component of an ink receiving layer, and the like.

1. Spherical silica particles The present invention has an average particle diameter in the range of 5 to 300 nm and a specific surface area of 50 to 1500 m ^2.
The present invention relates to spherical silica particles having an average particle diameter of 1 μm to 50 μm formed of a hollow silica fine particle aggregate in which hollow silica fine particles having a hollow structure are aggregated.

Hollow silica fine particles [structure, particle size and specific surface area]
As the hollow silica fine particles in the present invention, known hollow silica fine particles can be used.

  Examples of known hollow silica fine particles include hollow silica particles having a particle size of about 0.1 to 380 μm, as described in, for example, JP-A-6-330606 or JP-A-7-013137, As described in Japanese Patent Application Publication No. 11-029318, a micron-sized spherical structure having a core-shell structure in which the outer peripheral portion is a shell, the central portion is hollow, the outer shell is dense, and the inner portion is denser and has a coarser concentration gradient structure. Silica particles, hollow silica fine particles obtained by completely covering the surface of porous inorganic oxide fine particles with silica or the like as described in JP-A-7-133105, and JP-A-2001-233611 A silica coating layer is formed on core particles of a composite oxide composed of silica and an inorganic oxide other than silica as described in the public, and then an inorganic acid other than silica is formed. Objects are removed, there may be mentioned a hollow silica-based particles of the resulting nanometer-sized but is not limited thereto by coating the silica needed.

The hollow silica fine particle is not particularly limited as long as it has a pore structure inside the particle, and examples thereof include a fine particle having an outer shell layer and being porous or hollow inside. be able to. In the present invention, the hollow silica fine particles are aggregated and bound to form a spherical aggregate. As the hollow silica fine particles, those having an average particle diameter in the range of 5 to 300 nm and a specific surface area in the range of 50 to 1500 m ² / g are suitably used. When the average particle diameter is less than 5 nm, it is not easy to prepare hollow silica fine particles. When the average particle diameter exceeds 300 nm, the bonding force between the hollow silica fine particles is weak, and it is difficult to obtain an aggregate of hollow silica fine particles. Moreover, even if such an aggregate is obtained, the strength of the spherical silica particles is insufficient. The more preferable average particle diameter of the hollow silica fine particles is in the range of 5 to 120 nm. In the present application, the average particle diameter of the hollow silica fine particles means an average particle diameter measured by a dynamic light scattering method or an average particle diameter measured by an image analysis method. About the measuring method of the average particle diameter by the dynamic light scattering method, it described in [1A] "The measuring method of the average particle diameter by the dynamic light scattering method" of an Example. Further, the average particle size measurement method by the image analysis method was measured by the average particle size measurement method described in [5] “Measurement of particle size distribution” in Examples.

About the said hollow silica fine particle which has a hollow structure and exists in the said average particle diameter range, the specific surface area becomes the range of 50-1500 m < ² > / g. In the average particle size range, it is not easy to prepare hollow silica fine particles having a specific surface area exceeding 1500 m ² / g. On the other hand, when the specific surface area is less than 50 m ² / g, the hollow silica fine particles in the average particle diameter range may not have a hollow structure.

[Particle size distribution]
The hollow silica fine particles preferably have a particle size distribution in a monodispersed state. Specifically, those having a particle diameter variation coefficient (CV value) of 50% or less are preferable. The spherical silica particles according to the present invention are formed on the surface of a hollow silica fine particle aggregate, or a hollow silica fine particle aggregate, in which hollow silica fine particles having a highly uniform particle size distribution are assembled and settled. In particular, since the particle size distribution is in a monodisperse state, the effect of [insulating or heat resistance] is excellent when applied to [semiconductor applications]. When the particle diameter variation coefficient (CV value) exceeds 50%, such an effect is hardly generated because the uniformity of the particle diameter is low. The particle diameter variation coefficient (CV value) of the hollow silica fine particles is 10% or more and 50% or less, so that the effect of [insulation or heat resistance] can be sufficiently obtained. Not necessarily required.

As a means for enhancing the monodispersity of the particle size distribution of the hollow silica fine particles, there is a method of performing particle growth using uniform SEED [particles. Moreover, about the hollow silica sol which a hollow silica fine particle disperse | distributes to a dispersion medium, the method of removing a coarse particle can be mentioned by performing a microfiltration or a centrifugation process.

[shape]
The shape of the hollow silica fine particles is preferably spherical. Here, the spherical shape may be any degree as long as it is not visually recognized as an irregularly shaped particle such as a rod shape, a slug shape, an elongated shape, a bead shape, or an egg shape, but more preferably, the sphericity is 0. Those in the range of .90 to 1.00 are recommended. Here, the sphericity is the maximum diameter (DL) and the short diameter (DS) orthogonal to each of any 50 particles in a photographic projection obtained by photographing with a transmission electron microscope. Mean ratio (DS / DL). When the sphericity is less than 0.90, it cannot be said that the fine particles are spherical, and may include those corresponding to the irregular shaped particles. The spherical silica particles according to the present invention are structurally stable when the sphericity is in the range of 0.90 to 1.00 in addition to the uniformity of the particle diameter described above. This is preferable in terms. For hollow silica fine particles having a sphericity of less than 0.90, so-called hydrothermal treatment is performed to adjust the sphericity to a range of 0.90 to 1.00, and then the hollow silica fine particles in the present invention are used. Can be applied as Examples of the hydrothermal treatment conditions include a method of performing treatment at a temperature of 100 to 200 ° C. for 1 to 24 hours. It is also recommended to use an autoclave for the hydrothermal treatment.

[composition]
The composition of the hollow silica fine particles is not particularly limited as long as it contains silica, and elements or compounds other than silica may remain due to the raw material for producing the hollow silica fine particles. . Examples of such remaining elements and compounds include alumina, titania, zirconia, tin oxide, cerium oxide, sodium, potassium, and the like.

[Production method]
The hollow silica fine particles in the present invention may be prepared by a conventionally known production method. As an example of a known production method, active silica is precipitated from an alkali metal silicate aqueous solution as described in JP-T-2000-500113 on a core made of a material other than silica, and the silica shell is broken by the material. A method for producing hollow particles comprising a dense silica shell by removing without removal, and a core particle of a composite oxide comprising silica and an inorganic oxide other than silica as described in JP-A-2001-233611 A method for producing nanometer-sized hollow silica fine particles obtained by forming a silica coating layer on the substrate, then removing inorganic oxides other than silica, and coating silica as necessary is limited to these. Is not to be done.

Spherical silica particles The spherical silica particles according to the present invention have an average particle diameter in the range of 5 to 300 nm, a specific surface area in the range of 50 to 1500 m ² / g, and silica fine particles having a hollow structure are aggregated and bound. Spherical silica particles having an average particle diameter of 1 μm to 50 μm composed of a hollow silica fine particle aggregate. The spherical silica particles are aggregates of hollow silica fine particles and have voids inside thereof, and thus are spherical porous silica particles. About this spherical silica particle, it is preferable that the bulk specific gravity (CBD) exists in the range of 0.7-1.0 g / ml. Further, the particle size distribution of the hollow silica fine particles is preferably in a monodispersed state, and more specifically, the particle size variation coefficient (CV value) is preferably in the range of 10 to 50%.

[Particle size]
About the average particle diameter of the spherical silica particle in this invention, the range of 0.5-50 micrometers is preferable. According to the production method of the present invention described later, spherical and uniform spherical silica particles can be obtained within this range. According to the production method of the present invention, it is not easy to prepare spherical silica particles having an average particle diameter of less than 0.5 μm. When the average particle diameter exceeds 50 μm, irregular shapes are easily generated according to the production method of the present invention, which is not desirable. In addition, about the average particle diameter of a spherical silica particle, the range of 5-30 micrometers is recommended suitably.

  The average particle size of the spherical silica particles according to the present invention is measured by the centrifugal sedimentation method. For the specific measurement method, see [1B] “Measurement method of average particle size by centrifugal sedimentation method” in Examples. "

[Bulk specific gravity]
The bulk specific gravity (CBD) of the spherical silica particles is preferably in the range of 0.7 to 1.0 g / ml. Here, the bulk specific gravity has a smaller value as the proportion of the voids in the spherical silica particles is larger. For example, if it is in the range of 0.7 to 1.0 g / ml, application as a lightweight aggregate is possible. It becomes possible.

[surface treatment]
The spherical silica particles according to the present invention are desirably surface-treated as desired. The surface treatment causes 1) blocking of the pores present on the outer surface of the hollow silica fine particles, 2) flattening of the surface, 3) generation of a surface coating layer, etc., so when adding spherical silica particles to various media , There is an advantage that its inherent characteristics (refractive index, heat insulation, etc.) are not easily damaged.

When surface treatment is performed by adding an acid or alkali to the spherical aggregate and subjecting it to a hydrothermal treatment, the components of the spherical aggregate (one or more selected from silica, alumina, zirconia, titania or tungsten) are an acid or an alkali. By reacting, the pores on the surface of the spherical aggregate are blocked, and a coating layer is formed depending on the progress of the surface treatment. In this case, the components of the coating layer are substantially the same as the components of the spherical aggregate.

  When surface treatment is carried out by adding an acid or alkali and an organosilicon compound represented by the following general formula and / or a partial hydrolyzate thereof to the hollow silica fine particles and hydrotreating, a silica-based coating layer is formed. .

General formula: R _n Si (OR ′) _4-n
[However, R and R ′ are hydrocarbon groups selected from an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a vinyl group or an acrylic group, and n is 0, 1, 2 or 3 Is an integer. ]
In addition, when a surface treatment is performed by adding a silicic acid solution and an alkali to the hollow silica fine particles and performing a hydrothermal treatment, a coating layer made of silica is formed.

[Composition of spherical silica particles]
The composition of the spherical silica particles of the present invention is determined by the composition of the hollow silica fine particles, and as described above, contains silica, in addition to alumina, titania, zirconia, tin oxide, cerium oxide, sodium, You may contain potassium etc.

Method for Producing Spherical Silica Particles The method for producing spherical silica particles of the present invention includes the following steps.
(A) Preparation of hollow silica fine particle aggregate A spray solution containing a hollow silica fine particle dispersion is sprayed into an air stream to prepare a hollow silica fine particle aggregate. As the solvent of the hollow silica fine particle dispersion, water or an organic solvent is used. As the organic solvent, monohydric alcohols such as ethanol, propanol and butanol, polyhydric alcohols such as ethylene glycol, and the like can be used.

  The spray solution may contain a silicate solution, if desired, in addition to the hollow silica fine particle dispersion. By adding a silicic acid solution to the hollow silica fine particle dispersion as a spray solution, there is an effect of increasing the strength of the particles. The addition amount of the silicic acid solution is preferably 1.3 or more in [mass of hollow silica fine particles] / silicic acid solution (silica conversion). If it is less than 1.3, the proportion of silica derived from the silicic acid solution becomes excessive.

  About the density | concentration of the said spraying liquid, it is preferable to exist in the range of 5-60 weight% in conversion of solid content, especially 10-50 weight%. When the solid content concentration of the spray liquid is less than 5% by weight, it is difficult to obtain an aggregate. When the concentration of the spray solution exceeds 60% by weight, the spray solution becomes unstable and it becomes difficult to obtain a spherical aggregate. Moreover, the spray-drying mentioned later cannot be performed continuously, and the yield of an assembly falls.

  The spray drying method of the spray liquid is not particularly limited as long as the above-described aggregate can be obtained, and conventionally known methods such as a rotating disk method, a pressure nozzle method, and a two-fluid nozzle method can be employed. In particular, the two-fluid nozzle method disclosed in Japanese Examined Patent Publication No. 2-61406 is preferable because it can obtain a hollow silica fine particle aggregate having a uniform particle size distribution and can easily control the average particle size. .

  The drying temperature at this time varies depending on the concentration of the hollow silica fine particle dispersion, the processing speed, and the like, but when a spray dryer is used, for example, the inlet temperature of the spray dryer is 100 to 300 ° C., the spray rate is 0.5 to Conditions such as 3 L / min and an outlet temperature of 40 to 100 ° C. are preferable.

  The hollow silica fine particles used as the raw material in the step (A) are desirably hollow silica fine particles having a particle size distribution in a monodisperse phase. In this case, when the particle size distribution of the hollow silica fine particles is in a monodispersed state, it is applied to the step (A) as it is. On the other hand, when not in a monodispersed state, centrifugal separation is performed to remove coarse particles and make the particle diameter uniform. About the centrifugation process conditions, it carries out until particle diameter distribution shows a monodisperse phase. It is desirable to perform the treatment so that the particle variation coefficient (CV value) is in the range of 2 to 10%.

  Centrifugation processing conditions are not particularly limited as long as processing is performed in such a case that coarse particles are removed and the particle variation coefficient in the particle size distribution is 2 to 10%. Usually, it is recommended that the hollow silica fine particle dispersion has a solid content concentration of 1 to 50% by mass and a centrifugal force of 500 to 20000 G.

(B) Heat treatment of hollow silica fine particle aggregate The hollow silica fine particle aggregate obtained in the step (A) can be used as the spherical silica particle of the present invention. In order to raise, it is preferable to heat-process in the temperature range of 150-600 degreeC. When the heat treatment temperature is less than 150 ° C., the effect of improving the bonding strength is not observed, and when it exceeds 600 ° C., there is a possibility that the hollow silica fine particle aggregate may shrink, and the voids of the finally obtained spherical silica particles become smaller, which is preferable. Absent.

(C1) Preparation of Hollow Silica Fine Particle Aggregate Dispersion The hollow silica fine particle aggregate obtained in the step (B) is allowed to cool or cool to room temperature to 40 ° C. and dispersed in water and / or an organic solvent for dispersion. Prepare the solution. As the organic solvent, monohydric alcohols such as ethanol, propanol and butanol, polyhydric alcohols 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 hollow silica fine particle aggregate converted to an oxide. When the concentration is less than 0.1% by weight, an oxide-based component is deposited inside the hollow silica fine particle aggregate in the step (D), and it becomes difficult to selectively deposit on the outer surface. Large spherical silica particles are difficult to obtain. On the other hand, when the concentration exceeds 40% by weight, the aggregates easily aggregate in the step (D), which is not preferable.

(C2) Surface treatment If desired, the following i), ii) or iii) is added to the aggregate dispersion obtained in the step (C1) to treat the outer surface of the hollow silica fine particle aggregate.
i) Acid or alkali ii) Acid or alkali and an organosilicon compound represented by the following general formula and / or a partial hydrolyzate thereof General formula: R _n Si (OR ′) _4-n
[However, R and R 'is an alkyl group having 1 to 18 carbon atoms, the number 6-18 aryl group carbon atoms or a group Ru is selected from vinyl or acrylic group, n represents 0, 1, 2 or 3 It is an integer. ]
iii) Silicic acid solution and alkali In the case of i), an acid or alkali aqueous solution is usually used. The type of acid or alkali is not particularly limited, and examples include an aqueous hydrochloric acid solution, an aqueous boric acid solution, and an aqueous ammonium solution. As a treatment method, the particle aggregate is dispersed in a mixed solvent of water and alcohol, and the organosilicon compound of ii) is hydrolyzed by sequentially adding acid or ammonia.

The acid or alkali in the case of ii) is defined as in the case of i). Specific examples of the organosilicon compound represented by the general formula include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltrimethylsilane. Ethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, 3,3,3-trifluoropropyl Trimethoxysilane, methyl-3,3,3-trifluoropropyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxytripropyl Limethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldi Ethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ -Aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, trimethylsilanol Methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane and the like.

  In addition, although the acid or alkali added with an organosilicon compound and / or its partial hydrolyzate also functions as a catalyst for hydrolysis, a catalyst for hydrolysis may be added if desired. When a basic catalyst such as an alkali metal hydroxide, aqueous ammonia, or an amine is used as the hydrolysis catalyst, these basic catalysts can be removed after hydrolysis and used as an acidic solution. Moreover, when preparing a hydrolyzate using acidic catalysts, such as an organic acid and an inorganic acid, it is preferable to remove an acidic catalyst by ion exchange etc. after a hydrolysis. In addition, it is desirable to use the obtained hydrolyzate of the organosilicon compound in the form of an aqueous solution. Here, the aqueous solution means a state in which the hydrolyzate has transparency without being clouded as a gel.

  When spherical silica particles are used by blending with an organic resin, dispersibility in an organic solvent is good by using the above-mentioned organosilicon compound having n of 1 to 3 or a fluorine-substituted alkyl group-containing organosilicon compound, Spherical silica particles having high affinity with the organic resin can be obtained.

  In addition, although the compound whose n is 0 with an organosilicon compound can be used as it is, since the compound whose n is 1-3 is poor in hydrophilicity, it can mix uniformly with a reaction system by hydrolyzing beforehand. It is preferable to make it. For the hydrolysis, a well-known method can be adopted as a hydrolysis method of these organosilicon compounds.

In the case of iii), when a silicic acid solution is used, a predetermined amount of the silicic acid solution is added to the dispersion, and at the same time, the definition is the same as in the case of alkali (said i). ) To deposit the silicic acid solution on the outer surface of the aggregate particles. As the silicic acid solution, a silicic acid solution obtained by removing an alkali by treating an alkali silicate aqueous solution with a cation exchange resin or the like can be used. In particular, pH _{2 to} pH 4 and SiO ₂ concentration is about 7% by weight or less. The acidic silicic acid solution is preferred.

  Along with the above silicon compound and / or its partial hydrolyzate or silicic acid solution, a precursor metal salt of an inorganic oxide other than the oxide described above is added to form an oxide and an inorganic oxide other than the oxide. An oxide-based layer can also be formed. As the raw material of the inorganic oxide other than the oxide, an alkali-soluble inorganic compound is preferably used. The above-described alkali metal salt or alkaline earth metal salt of an oxo acid of a metal or nonmetal, an ammonium salt, a quaternary salt. Mention may be made of ammonium salts.

  The dispersion of the hollow silica fine particle aggregate coated with the oxide-based layer can be washed by a known washing method such as ultrafiltration. In this case, ultrafiltration may be performed after a part of alkali metal ions, alkaline earth metal ions, ammonium ions and the like in the dispersion is previously removed with an ion exchange resin or the like.

  Next, the particles can be separated from the dispersion by filtration and dried to obtain first spherical silica particles. Since an oxide-based layer is formed on the outer surface of the spherical silica particles, other than 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 silica 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 oxide-based layer. In order to be maintained, it has a low refractive index and a heat insulating effect.

(C3) Hydrothermal treatment The hollow silica fine particle aggregate is coated by hydrothermally treating the hollow silica fine particle aggregate dispersion obtained in the (C1) or (C2) step at a temperature range of 50 to 350 ° C. The oxide-based layer can be densified. That is, by reducing or eliminating the pores of the oxide-based layer, the solvent and / or gas remains in the internal voids of the spherical silica particles.

  Hydrothermal treatment is performed by adding an alkaline aqueous solution to the dispersion as necessary, preferably adjusting the pH in the range of 8 to 13, and heat treatment. The heat treatment temperature at this time is particularly preferably in the range of 100 to 300 ° C. In the heat treatment, the dispersion can be diluted in advance or concentrated. Thereafter, the hydrothermally treated dispersion liquid may be washed in the same manner as in the step (C2). Finally, the particles are filtered and separated from the hydrothermally treated dispersion liquid and dried to obtain a second product. Spherical silica particles can be obtained. Since these spherical silica particles have a dense oxide-based coating layer, a low refractive index and a heat insulating effect are promoted.

(D) Heat treatment Further, the hollow silica fine particle aggregate is separated from the hollow silica fine particle aggregate dispersion obtained in step (C3) by filtration or the like, dried, and then at 400 to 1200 ° C. under atmospheric pressure or reduced pressure. Heat treatment can be performed to obtain third spherical silica particles whose internal voids are sealed with the oxide-based layer. When the heat treatment temperature is less than 400 ° C., the pores of the oxide-based layer cannot be completely closed and densified. On the other hand, when the heat treatment temperature exceeds 1200 ° C., the spherical silica particles are easily fused to each other, and it is difficult to maintain the spherical shape. The third spherical silica particles have a very low refractive index because no solvent is present in the voids. Therefore, the film obtained using these particles has a low refractive index, and the coated substrate is excellent in antireflection performance. Moreover, the film | membrane which laminated | stacked this particle | grain has the outstanding heat insulation effect.

(Example)
Subsequently, examples and comparative examples will be described. Before that, measurement methods for characteristics in the examples and comparative examples will be described.

[1A] Method for Measuring Average Particle Diameter by Dynamic Light Scattering Method For the average particle diameter of the hollow silica fine particles prepared in Synthesis Example 1-1, Synthesis Example 1-2, and Synthesis Example 1-3, the sample oxide sol is used. The mixture was diluted with 0.58% aqueous ammonia to adjust the oxide concentration to 1% by mass, and the average particle size was measured using the following particle size measuring apparatus.

[Particle size measuring device]
Laser particle analyzer (manufactured by Otsuka Electronics, Laser particle size analysis system: LP
-510 model PAR-III, measurement principle: dynamic light scattering method, measurement angle 90 °, light receiving element photomultiplier tube 2 inches, measurement range 3 nm to 5 μm, light source He-Ne laser 5 mW 632.8 nm, temperature adjustment range 5 to 90 ℃, temperature adjustment Peltier element (cooling), ceramic heater (heating), cell
10mm square plastic cell, measurement object: colloidal particles)
In addition, about the average particle diameter of the hollow silica fine particle prepared by the synthesis example 2-1, the synthesis example 2-2, and the synthesis example 2-3, it measured with the measuring method of the average particle diameter described in the postscript [5].

[1B] Method for Measuring Average Particle Diameter by Centrifugal Sedimentation Method Regarding the average particle diameter of the spherical silica particles, first, a dispersion of spherical silica particles (water or 40 mass% glycerin solvent, solid content concentration 0.1 to 5 mass%). ) For 5 minutes using an ultrasonic generator (US-2, manufactured by Iuch). Furthermore, a part of the dispersion is taken into a glass cell (size of 10 mm in length, 10 mm in width and 45 cm in height) from a dispersion whose concentration is appropriately adjusted by adding water or glycerin, and centrifugal sedimentation type particle size distribution measurement The average particle diameter was measured using an apparatus (manufactured by Horiba: CAPA-700).
The average particle size of the spherical aggregate of hollow silica fine particles was also measured in the same manner.

[2] Specific gravity measurement method For the specific gravity of the spherical silica particles, first, a 10 g sample is taken in a crucible and dried at 110 ° C. for 2 hours. Next, after cooling with a desiccator, 3 to 4 g is put into a 25 ml pycnometer, distilled water is added and suspended, vacuum deaeration is performed at 60 mmHg for 1 hour, and the temperature is adjusted in a 25 ° C. constant temperature bath. Distilled water is added to the mark of the pycnometer to adjust the volume, and the sample volume (ml) is calculated from the difference between the pycnometer volume (25 ml) and the distilled water volume (ml). The density was determined from the weight (g) of the added sample and the calculated volume (ml).

[3] Measuring method of sphericity Arbitrary 50 in the photographic projection figure obtained by photographing a sample oxide sol at a magnification of 250,000 times with a transmission electron microscope (H-800, manufactured by Hitachi, Ltd.) About each particle | grain, ratio (DS / DL) of each largest diameter (DL) and the short diameter (DS) orthogonal to this was measured, and those average values were made into sphericity.

[4] Measurement of particle size distribution Particles were photographed (magnification: 250,000 times) using a scanning electron microscope (manufactured by JEOL Ltd., JSM-5300 type), and an image analyzer was used for 250 particles of this image. (Asahi Kasei Co., Ltd., IP-1000) was used to measure the average particle size and calculate the coefficient of variation (CV value) regarding the particle size distribution. Specifically, the particle diameter of each of 250 particles was measured, and the average particle diameter and the standard deviation of the particle diameter were determined from the measured values, and calculated from the following formula.
Coefficient of variation (CV value) = (particle diameter standard deviation (σ) / average particle diameter (D _n )) × 100

[5] pH measurement Approximately 50 g of a sample for measurement was collected in a polyethylene sample bottle, immersed in a thermostatic bath at 25 ° C. for 30 minutes or more, and then corrected with standard solutions of pH 4, 7 and 9 A glass electrode of a pH meter F22 manufactured by HORIBA, Ltd. was inserted to carry out.

[6] Measurement of particle breaking strength For particle breaking strength, a single spherical silica particle (particle diameter 10 ± 1 μm) was used as a sample, and a micro compression tester (manufactured by Shimadzu Corporation, MCTM-200) was used. A load is applied to the sample at a constant load speed, and the weight at the time when the particles are broken is defined as the compressive strength (kgf / mm ² ). Further, this operation was repeated four times, and the compressive strength was measured for five samples, and the average value was taken as the particle compressive strength.

[7] Method for Measuring Bulk Specific Gravity An “apparent density measuring device” described in JIS K3362 is placed horizontally, and about 120 mL of spherical silica particles are naturally dropped from a funnel into a weighed cup. Remove the sample from the cup and weigh the cup. The bulk specific gravity is [weight of the sample in the cup (g)] / [capacity of the cup (mL)].
[Synthesis Example 1]

According to Example 2 of JP-A-2001-233611, hollow silica fine particles were prepared by the following method.
A mixture of 100 g of silica sol having an average particle diameter of 5 nm and a SiO ₂ concentration of 20% by weight and 1900 g of pure water was heated to 80 ° C. The pH of this reaction mother liquor was 10.5. In the mother liquor, 9000 g of a 1.17 wt% sodium silicate aqueous solution as SiO ₂ and 0.83 wt% as Al ₂ O ₃ were added.
9000 g of sodium aluminate aqueous solution was added simultaneously. Meanwhile, the temperature of the reaction solution was kept at 80 ° C. The pH of the reaction solution rose to 12.5 immediately after the addition, and hardly changed thereafter. After completion of the addition, the reaction solution was cooled to room temperature and washed with an ultrafiltration membrane to prepare a SiO ₂ .Al ₂ O ₃ core particle dispersion with a solid concentration of 20 wt%. (Process (a))

1,700 g of pure water is added to 500 g of this core particle dispersion and heated to 98 ° C., and while maintaining this temperature, a silicic acid solution (SiO ₂₎ obtained by dealkalizing a sodium silicate aqueous solution with a cation exchange resin. A dispersion of core particles in which a first silica coating layer was formed by adding 3,000 g (concentration 3.5 wt%) was obtained. (Process (b))

1,125 g of pure water was added to 500 g of the core particle dispersion formed with the first silica coating layer that had been washed with an ultrafiltration membrane to a solid content concentration of 13% by weight, and concentrated hydrochloric acid (35.5%) was added dropwise. The pH was adjusted to 1.0 and dealumination was performed. Next, the aluminum salt dissolved in the ultrafiltration membrane was separated while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, and SiO ₂ · Al from which some of the constituent components of the core particles forming the first silica coating layer were removed. A dispersion of ₂ O ₃ porous particles was prepared (step (c)). 1500 g of the above porous particle dispersion, 500 g of pure water, ethanol 1
, 750 g, and 626 g of 28% ammonia water were heated to 35 ° C., 104 g of ethyl silicate (SiO ₂ 28 wt%) was added, and the surface of the porous particles on which the first silica coating layer was formed was A second silica coating layer was formed by coating with a hydrolyzed polycondensate of silicate. Next, a dispersion of silica-based fine particles having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane. When the obtained silica-based fine particles were observed with a scanning electron microscope (SEM), they were found to be hollow silica fine particles having an average particle diameter of 46 nm and an outer layer thickness of 10 nm.
[Synthesis Example 2]

According to Comparative Example 2 of JP-A-2001-233611, hollow silica fine particles were prepared by the following method.
A reaction mother liquor was prepared by mixing 10 g of silica sol having an average particle diameter of 5 nm and a SiO ₂ concentration of 20% by weight with 190 g of pure water, and heated to 95 ° C. The pH of this reaction mother liquor is 10.5. In the mother liquor, 24,900 g of 1.5 wt% sodium silicate aqueous solution as SiO ₂ and 36,800 g of 0.5 wt% sodium aluminate aqueous solution as Al ₂ O ₃ are added. Were added simultaneously. Meanwhile, the temperature of the reaction solution was maintained at 95 ° C. The pH of the reaction solution rose to 12.5 immediately after the addition of sodium silicate and sodium aluminate, and hardly changed thereafter. After completion of the addition, the reaction solution was cooled to room temperature and washed with an ultrafiltration membrane to prepare a SiO ₂ .Al ₂ O ₃ core particle dispersion with a solid concentration of 20 wt%. Next, 500 g of this nuclear particle dispersion was sampled, 1,700 g of pure water was added and heated to 98 ° C., and this sodium silicate aqueous solution was dealkalized with a cation exchange resin while maintaining this temperature. A first silica coating layer was formed on the surface of the core particles by adding 3,000 g of a silicic acid solution (SiO ₂ concentration 3.5 wt%). The obtained core particle dispersion was washed with an ultrafiltration membrane to adjust the solid content concentration to 13% by weight, and then 1,125 g of pure water was added to 500 g of the core particle dispersion, and further concentrated hydrochloric acid (35.5% ) Was dropped to pH 1.0, and after dealumination treatment, the aluminum salt dissolved in the ultrafiltration membrane was separated while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water to form a first silica coating layer A porous particle dispersion was prepared. A mixture of 1500 g of the porous particle dispersion having the first silica coating layer and 500 g of pure water, 1,750 g of ethanol and 626 g of 28% ammonia water was heated to 35 ° C., and then ethyl silicate (SiO ₂ 28 (Weight%) 104g was added, and the 2nd silica coating layer was formed with the hydrolysis polycondensate of the ethyl silicate on the surface of the porous particle in which the 1st silica coating layer was formed. Next, after concentration with an evaporator to a solid content concentration of 5 wt%, ammonia water with a concentration of 15 wt% is added to adjust the pH to 10, heat treatment is performed at 180 ° C. for 2 hours in an autoclave, and the solvent is changed to ethanol using an ultrafiltration membrane. A dispersion of silica-based fine particles having a substituted solid content concentration of 20% by weight was prepared. The obtained silica-based fine particles were found to be hollow silica fine particles having an average particle diameter of 96 nm and an outer layer thickness of 10 nm.

  A hollow silica sol 5L having a silica concentration of 20% by mass obtained by the same production method as in Synthesis Example 1 is used as a rotor (model: QNS, capacity: 1 L) of a centrifuge (manufactured by Kokusan Co., Ltd., continuous high-speed centrifuge H-660). The solution was continuously injected into the 7000 G and passed at 7000 G at a rate of 400 g / min, and the solution was continuously collected, whereby the coarse particles were centrifuged. Coarse particles precipitated in the rotor.

This hollow silica sol has an average particle diameter of 46 nm, a specific surface area of 121 m ² / g, and a sphericity of 0.9.
3 was a hollow silica sol in which silica fine particles 3 were dispersed in water. The particle variation coefficient (CV value) of the hollow silica sol was 30%, and it was found that the hollow silica fine particles were monodispersed.

  To 2000 g of this hollow silica sol diluted with water (silica concentration 12.6%), 50 g of cation exchange resin (Made by Mitsubishi Chemical Co., Ltd., Diaion SK-1BH) was added and stirred, and the pH became 3.5 or less. Upon separation, the cation exchange resin was separated.

Next, 2625 g of silicic acid solution (silica concentration: 4.8% by mass) was obtained by passing 0.2 L of cation exchange resin (manufactured by Mitsubishi Chemical Corporation, Diaion SK-1BH) at a space velocity of 3.1. 2600 g of a high-purity silicic acid solution having a solid content of 4.8% by weight was added to 1980 g of the hollow silica sol (corresponding to [silica mass in silica sol] / [silica mass in silicic acid solution] = 2) and stirred to obtain a slurry (solid The partial concentration was 8.2% by mass).

  The obtained slurry was subjected to a spray dryer (NIRO ATMIZER, manufactured by NIRO), and spray drying was performed under the conditions of an inlet temperature of 240 ° C., an outlet temperature of 55 ° C., and a spraying speed of 2 liters / minute to obtain a hollow silica fine particle aggregate. It was.

The obtained hollow silica fine particle aggregate was heated at a temperature of 450 ° C. for 6 hours to obtain 260 g of a hollow silica fine particle aggregate having an average particle diameter of 10 μm.
A hollow silica fine particle aggregate dispersion was prepared by suspending 260 g of the obtained hollow silica fine particle aggregate in 1300 g of pure water and stirring. A 15% aqueous ammonia solution was added until the pH of the dispersion reached 10.5, and the dispersion was filled into an autoclave, placed in the autoclave, hydrothermally treated at a temperature of 150 ° C. for 16 hours, and then cooled to room temperature. Extracted.

The obtained slurry was dehydrated with Nutsche, and 1500 g of pure water at 60 ° C. was added to the obtained cake for washing, followed by dehydration treatment. The obtained washed cake was dried at a temperature of 110 ° C. for 18 hours to obtain 240 g of a spherical powder. Furthermore, this powder was fired at a temperature of 800 ° C. for 6 hours to obtain spherical silica particles. The analysis results of the spherical silica particles are shown in Table 4. Moreover, the physical-property value of the used hollow silica fine particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3.

  The amount of the silicic acid solution used in Example 1 was changed to 3465 g (corresponding to [silica mass in hollow silica sol] / [silica mass in silicic acid solution] = 1.5), and the solid content concentration of the slurry was 7.6 mass. %, A hollow silica fine particle aggregate was prepared under the same conditions as in Example 1. The obtained hollow silica fine particle aggregate had an average particle size of 48 μm. The obtained spherical silica fine particle aggregate was treated in the same manner as in Example 1 to obtain spherical silica particles. Table 4 shows the analysis results of the spherical silica particles. Moreover, the physical-property value of the used hollow silica fine particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3.

  The amount of the silicic acid liquid used in Example 1 was changed to 1299 g (corresponding to [silica mass in hollow silica sol] / [silica mass in silicic acid liquid] = 4), and the solid content concentration of the slurry was 9.5 mass%. A hollow silica fine particle aggregate was prepared under the same conditions as in Example 1. About the obtained hollow silica fine particle aggregate | assembly, the process similar to Example 1 was performed and the spherical silica particle was obtained. Table 4 shows the analysis results of the spherical silica particles. Moreover, the physical-property value of the used hollow silica fine particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3.

  A hollow silica sol 5L having a silica concentration of 20% by mass obtained by the same production method as in Synthesis Example 1 is used as a rotor (model: QNS, capacity: 1 L) of a centrifuge (manufactured by Kokusan Co., Ltd., continuous high-speed centrifuge H-660). The solution was continuously injected into the 7000 G and passed at 7000 G at a rate of 400 g / min, and the solution was continuously collected, whereby the coarse particles were centrifuged. Coarse particles precipitated in the rotor.

  This silica sol was a silica sol in which silica fine particles having an average particle diameter of 46 nm and a sphericity of 0.93 were dispersed in water. The CV value of this silica sol was 30%, and it was found that spherical silica fine particles were monodispersed.

  1600 g of this silica sol diluted with water (solid content concentration: 10.0% by mass) is supplied to a spray dryer (NIRO, manufactured by NIRO ATMIZER) under the conditions of an inlet temperature of 240 ° C., an outlet temperature of 55 ° C., and a spray rate of 2 liters / minute. Spray drying was performed to obtain 180 g of a hollow silica fine particle aggregate. A hollow silica fine particle aggregate dispersion was prepared by suspending 180 g of the obtained hollow silica fine particle aggregate in 720 g of pure water and stirring. A 15% aqueous ammonia solution was added until the pH of the dispersion reached 10.5, and the dispersion was charged into an autoclave, aged at 150 ° C. for 16 hours and then cooled to room temperature and extracted. . The obtained slurry was dehydrated with Nutsche, and 1500 g of pure water at 60 ° C. was added to the obtained cake for washing, followed by dehydration treatment.

  The obtained washed cake was dried at a temperature of 110 ° C. for 18 hours to obtain 160 g of a spherical powder. Furthermore, this powder was fired at a temperature of 800 ° C. for 6 hours to obtain spherical silica particles. Table 4 shows the analysis results of the spherical silica particles. Moreover, the physical-property value of the used hollow silica fine particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3.

A hollow silica sol 5L having a silica concentration of 20% by mass obtained by the same production method as in Synthesis Example 2 was used as a rotor (model: QNS, manufactured by Kokusan Co., Ltd., continuous high-speed centrifuge H-660).
The solution was continuously injected into a volume of 1 L), passed at 7000 G at a rate of 400 g / min, and the liquid was continuously collected, whereby coarse particles were centrifuged. Coarse particles precipitated in the rotor.

This hollow silica sol has an average particle size of 96 nm, a specific surface area of 58 m ² / g, and a sphericity of 0.95.
It was a hollow silica sol obtained by dispersing silica fine particles in water. The particle variation coefficient (CV value) of the hollow silica sol was 30%, and it was found that the hollow silica fine particles were monodispersed.

  To 2000 g of this hollow silica sol diluted with water (silica concentration 12.6%), 50 g of cation exchange resin (Made by Mitsubishi Chemical Co., Ltd., Diaion SK-1BH) was added and stirred, and the pH became 3.5 or less. Upon separation, the cation exchange resin was separated.

Next, 2625 g of silicic acid solution (silica concentration: 4.8% by mass) was obtained by passing 0.2 L of cation exchange resin (manufactured by Mitsubishi Chemical Corporation, Diaion SK-1BH) at a space velocity of 3.1. 2600 g of a high-purity silicic acid solution having a solid content of 4.8% by weight was added to 1980 g of the hollow silica sol (corresponding to [silica mass in silica sol] / [silica mass in silicic acid solution] = 2) and stirred to obtain a slurry (solid The partial concentration was 8.2% by mass).

  The obtained slurry was applied to a spray dryer (NIRO ATMIZER, manufactured by NIRO), spray drying was performed under the conditions of an inlet temperature of 240 ° C., an outlet temperature of 55 ° C., and a spray rate of 2 liters / minute, and 260 g of spherical hollow silica fine particle aggregates Got.

  A hollow silica fine particle aggregate dispersion was prepared by suspending 260 g of the obtained hollow silica fine particle aggregate in 1300 g of pure water and stirring. A 15% aqueous ammonia solution was added until the pH of the dispersion reached 10.5, and the temperature of the dispersion was maintained at 35 ° C., while tetraethoxysilane (manufactured by Tama Chemical Industries, Ltd .: 20 g of ethyl silicate-A, SiO2 concentration 28% by weight) was added over 14 minutes. The dispersion was then filled into an autoclave, placed in an autoclave, hydrothermally treated at a temperature of 150 ° C. for 16 hours, and then cooled to room temperature and extracted.

The obtained slurry was dehydrated with Nutsche, and 1500 g of pure water at 60 ° C. was added to the obtained cake for washing, followed by dehydration treatment. The obtained washed cake was dried at a temperature of 110 ° C. for 18 hours to obtain 240 g of a spherical powder. Furthermore, this powder was fired at a temperature of 800 ° C. for 6 hours to obtain spherical silica particles. Table 4 shows the analysis results of the spherical silica particles. Moreover, the physical-property value of the used hollow silica fine particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3.
[Comparative Example 1]

Table 4 shows the results of measuring the breaking strength of the porous silica fine particles (fused silica) having an average particle diameter of 3.4 μm and a specific gravity of 1.1.
[Comparative Example 2]

Table 4 shows the results of measuring the breaking strength of the non-porous silica fine particles (fused silica) having an average particle diameter of 8.1 μm and a specific gravity of 2.2.
[Comparative Example 3]

Spherical silica particles were prepared according to Example 6 described in JP-A No. 2002-160907.
Specifically, a silica sol is prepared by mixing 800 g of silica sol (catalyst SI-50, Cataloid SI-50, average particle diameter 25 nm, concentration 50% by weight) with water 450 g, and a dry air flow at a temperature of 105 ° C. The two fluid nozzles were spray dried by supplying one of the two fluid nozzles at a flow rate of 5 kg / hr and the other nozzle at a flow rate of 2 kg / hr. This powder was fired at 500 ° C. for 5 hours to obtain a silica fine particle aggregate. The average particle diameter and pore volume of this silica fine particle aggregate were measured, and the results are shown in Table 1.

Next, 20 g of the silica fine particle aggregate is dispersed in a mixed solvent obtained by adding 400 g of ammonia water having a concentration of 29 wt% to 1300 g of pure water and 1100 g of ethanol, and while maintaining the temperature of the dispersion at 35 ° C., the organosilicon compound is added thereto. 14 g of tetraethoxysilane (manufactured by Tama Chemical Industry Co., Ltd .: ethyl silicate-A, SiO ₂ concentration 28 wt%) was added over 14 minutes. Next, this dispersion is filled in an autoclave, hydrothermally treated at 180 ° C. for 10 hours, cooled, filtered, dried (180 ° C., 16 hours), and further fired at 800 ° C. for 6 hours to make porous. Silica particles were obtained. Table 4 shows the analysis results of the porous silica particles. Moreover, the physical-property value of the used silica particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3. [Comparative Example 4]

Spherical silica particles (G) were prepared according to Example 7 described in JP-A No. 2002-160907.
Specifically, silica sol (catalyst chemical industry Co., Ltd. product: Cataloid SI-50, average particle size 25 nm, concentration 50% by weight) 400 g, water 60 g and Aerosil (Nippon Aerosil Co., Ltd. product: average particle size 0. (05 μm) 133 g was added, and water was added thereto to prepare a silica sol having a concentration of 20% by weight. In a dry air flow at a temperature of 105 ° C., a flow rate of 5 kg / hr was applied to one of the two-fluid nozzles, and the other nozzle was supplied. The gas pressure was supplied at a flow rate of 2 kg / hr and spray-dried. This powder was fired at 500 ° C. for 5 hours to obtain a silica fine particle aggregate. The average particle diameter and pore volume of this silica fine particle aggregate were measured, and the results are shown in Table 1.

Next, 20 g of the silica fine particle aggregate is dispersed in a mixed solvent obtained by adding 400 g of ammonia water having a concentration of 29 wt% to 1300 g of pure water and 1100 g of ethanol, and while maintaining the temperature of the dispersion at 35 ° C., the organosilicon compound is added thereto. 14 g of tetraethoxysilane (manufactured by Tama Chemical Industry Co., Ltd .: ethyl silicate-A, SiO ₂ concentration 28 wt%) was added over 14 minutes. Next, this dispersion is filled in an autoclave, hydrothermally treated at 180 ° C. for 10 hours, cooled, filtered, dried (180 ° C., 16 hours), and further fired at 800 ° C. for 6 hours to make porous. Silica particles were obtained. Table 4 shows the analysis results of the porous silica particles. Moreover, the physical-property value of the used silica particle and the manufacturing conditions of a spherical silica particle are described in Tables 1-3.

  The spherical silica particles of the present invention have a low specific gravity and a good particle breaking strength, and since these spherical silica particles have heat insulating properties, they are suitable as lightweight aggregates such as heat insulating materials, sound deadening materials, soundproofing materials, etc. It is. Moreover, if it is used for cosmetics, a foundation that is very light, soft, and stretched can be obtained.

  In addition, extenders for inks, toners, release improvers, lubricants, abrasives such as automotive wax, high-hardness fillers for improving resin and rubber wear resistance, fluidity improvers, matte fillers, no shrinkage Examples of fillers, putty fillers, adsorbents, chromatographic carriers, fragrance inclusion beads, bactericides / insecticides / antifungal inclusion beads, liquid crystal inclusion beads and the like can also be exemplified.

Claims (9)

The average particle diameter is in the range of 5 to 300 nm, the specific surface area is in the range of 50 to 1500 m ² / g, and the average is composed of a hollow silica fine particle aggregate in which hollow silica fine particles having a hollow structure are assembled and bound. Spherical silica particles having a particle diameter of 1 μm to 50 μm.   2. The spherical silica particles according to claim 1, wherein the bulk specific gravity (CBD) is in the range of 0.7 to 1.0 g / ml. The average particle diameter is in the range of 5 to 300 nm, the specific surface area is in the range of 50 to 1500 m ² / g, and the average is composed of a hollow silica fine particle aggregate in which hollow silica fine particles having a hollow structure are assembled and bound. Spherical silica particles having a particle diameter of 1 μm to 50 μm, a bulk specific gravity (CBD) in the range of 0.7 to 1.0 g / ml, and a particle breaking strength in the range of 0.5 to 100 Kgf / mm ^2. Spherical silica particles characterized by   The spherical silica particles according to any one of claims 1 to 3, wherein a particle size distribution of the hollow silica fine particles is in a monodispersed state.   The method for producing spherical silica particles according to any one of claims 1 to 4, wherein a hollow silica fine particle aggregate is prepared by spraying a spray liquid containing a hollow silica fine particle dispersion in an air stream. The manufacturing method of the spherical silica particle of Claim 5 including each following process.
(A): A step of spraying a spray liquid containing a hollow silica fine particle dispersion in an air stream to prepare a hollow silica fine particle aggregate (B): The temperature of the hollow silica fine particle aggregate obtained in the step (A) Step (C1) of heat treatment in the range of 150 to 600 ° C .: Following the step (B), the hollow silica fine particle aggregate is dispersed in water and / or an organic solvent to prepare a hollow silica fine particle aggregate dispersion. Step (D): Following the step (C 1 ), spherical silica particles are separated from the hollow silica fine particle aggregate dispersion, dried, and then heated at 400 to 1200 ° C. under atmospheric pressure or reduced pressure. Process to process After the step (C1), the step (D) is performed after the step (C2) or the step (C3) or after the step (C3) after the step (C3). method of manufacturing a spherical boss silica particles of claim 6, wherein.
(C2): A step of surface-treating the hollow silica fine particle aggregate by adding the following i), ii) or iii) to the dispersion of the hollow silica fine particle aggregate prepared in the step (C1)
i) Acid or alkali
ii) Acid or alkali and an organosilicon compound represented by the following general formula and / or a partial hydrolyzate thereof General formula: R _n Si (OR ′) _4-n
[However, R and R 'is an alkyl group having 1 to 18 carbon atoms, the number 6-18 aryl group carbon atoms or a group Ru is selected from vinyl or acrylic group, n represents 0, 1, 2 or 3 It is an integer. ]
iii) Silicic acid solution and alkali (C3): Hydrothermal treatment of the hollow silica fine particle aggregate dispersion at 50 to 350 ° C.   The method for producing spherical silica particles according to claim 6 or 7, wherein the spray liquid in the step (A) further contains a silicic acid liquid.   The method for producing spherical silica particles according to any one of claims 6 to 8, wherein a particle size distribution of the hollow silica fine particle dispersion in the step (A) is in a monodispersed state.