Aluminosilicate hollow particles

Abstract

To provide an aluminosilicate hollow particle having a low bulk density and a high compressibility ratio.SOLUTION: In an aluminosilicate hollow particle, a bulk density is 0.015 g / cm3 or less, and a compressibility ratio is 85% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to aluminosilicate hollow particles. [Background technology]

[0002] Inorganic oxide hollow particles are used in the fields of heat insulation materials, heat shielding materials, soundproofing and absorbing materials, catalyst carriers, building materials, and electronic materials. For example, inorganic oxide hollow particles include fine aluminosilicate hollow particles having a shell that defines a hollow chamber, and having a composition of SiO 2 Content 70~90% by mass, Al 2 O 3 Content 10~30% by mass, Fe 2 O 3 Aluminosilicate hollow fine particles are known which have a content of 1 mass % or less, an average circularity of 0.85 or more, an average particle size of 1 μm to 20 μm, a shell thickness of 500 nm or less, and a softening start temperature of 1100° C. or more (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-121026 A Summary of the Invention [Problem to be solved by the invention]

[0004] Since aluminosilicate hollow particles have cavities surrounded by an outer shell, they are lighter than non-hollow particles, but a low bulk density is advantageous for further weight reduction. However, when the bulk density of aluminosilicate hollow particles is low, the volume increases, which increases the effort and cost required for transportation. In this case, if the aluminosilicate hollow particles can be compressed without being damaged, the volume can be reduced, thereby reducing the load during transportation. An object of the present invention is to provide aluminosilicate hollow particles having a low bulk density and a high compressibility. [Means for solving the problem]

[0005] The present inventors have conducted research in light of the above problems and have found aluminosilicate hollow particles that have a lower bulk density and a higher compression ratio than conventional particles.

[0006] That is, the present invention provides the following [1] to [4]. [1] Bulk density is 0.015g / cm 3 The aluminosilicate hollow particles have a compressibility of 85% or more. [2] The aluminosilicate hollow particles according to [1] above, having a circularity of 0.70 or less. [3] The aluminosilicate hollow particles according to [1] or [2] above, having an angle of repose of 50° or more. [4] BET specific surface area is 15m 2 / g or more. Effect of the Invention

[0007] According to the present invention, it is possible to provide aluminosilicate hollow particles having a low bulk density and a high compressibility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In this specification, "aluminosilicate" refers to a compound in which part of the silicon in silicate is replaced with aluminum, and is represented by SiO 2 and Al 2 O 3 The total content of these compounds is 65% by mass or more. In addition, in this specification, "hollow particles" refers to particles having a cavity (hollow structure) inside. The cavity is surrounded by an outer shell, and there may be one or more cavities. Therefore, hollow particles are different from porous particles having multiple pores extending from the surface of the particle to the inside. Note that hollow particles can be clearly distinguished from porous particles by scanning electron microscope (SEM) images.

[0009] The aluminosilicate hollow particles of the present invention have an outer shell formed of an aluminosilicate. The aluminosilicate hollow particles of the present invention are SiO 2 and Al 2 O 3 The total content of SiO and SiO is 65% by mass or more, but from the viewpoint of low bulk density and high compressibility, it is preferably 70% by mass or more, more preferably 75% by mass or more, and further preferably 80% by mass or more. 2 and Al 2 O 3 The upper limit of the total content of these may be 100% by mass. In addition, SiO 2 and Al 2 O 3 Mass ratio to Al 2 O 3 / SiO 2 ) is preferably from 0.2 to 0.3, more preferably from 0.21 to 0.28, and even more preferably from 0.23 to 0.26, from the viewpoints of low bulk density and high compressibility.

[0010] SiO 2 In view of low bulk density and high compressibility, the content of in the aluminosilicate hollow particles is preferably 60 mass % or more, more preferably 61 mass % or more, even more preferably 63 mass % or more, even more preferably 65 mass % or more, and is preferably 80 mass % or less, more preferably 79 mass % or less, and even more preferably 78 mass % or less. Al 2 O 3 In view of low bulk density and high compressibility, the content of in the aluminosilicate hollow particles is preferably 15% by mass or more, more preferably 16% by mass or more, and even more preferably 17% by mass or more, and is preferably 25% by mass or less, more preferably 23% by mass or less, and even more preferably 21% by mass or less.

[0011] The aluminosilicate hollow particles of the present invention may contain a metal other than silicon and aluminum to compensate for the positive charge lost by replacing a part of the silicon of the silicate with aluminum. Examples of metal oxides containing a metal other than silicon and aluminum include oxides of Group 1 elements, oxides of Group 2 elements, boron oxides, and oxides of Group 4 elements.

[0012] Examples of Group 1 element oxides include Li 2 O, Na 2 OK 2 O, Rb 2 O, Cs 2 One example is O. Examples of Group 2 element oxides include MgO, CaO, SrO, BaO, and RaO. Boron oxide is B 2 O 3 is preferred. Examples of Group 4 element oxides include TiO 2 , ZrO 2 , HfO 2 Examples include:

[0013] The content of the metal oxide containing a metal other than silicon and aluminum can be appropriately selected within a range that does not impair the effects of the present invention, and can be, for example, in the following embodiment. From the viewpoint of low bulk density and high compressibility, the content of the Group 2 element oxide in the aluminosilicate hollow particles is preferably 12 mass% or less, more preferably 10 mass% or less, even more preferably 8 mass% or less, and even more preferably 6 mass% or less. The lower limit of the content of the Group 2 element oxide in the aluminosilicate hollow particles is not particularly limited and may be 0 mass%, but from the viewpoint of low bulk density and high compressibility, it is preferably 0.5 mass% or more, more preferably 1 mass% or more, and even more preferably 2 mass% or more. From the viewpoint of low bulk density and high compressibility, the content of boron oxide in the aluminosilicate hollow particles is preferably 20% by mass or less, more preferably 19% by mass or less, more preferably 15% by mass or less, and even more preferably 12% by mass or less. The lower limit of the content of boron oxide in the aluminosilicate hollow particles is not particularly limited, and may be 0% by mass or less, but is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more.

[0014] Among them, as metal oxides containing metals other than silicon and aluminum, from the viewpoint of low bulk density and high compressibility, oxides of group 2 elements and B 2 O 3 Preferably, one or more selected from MgO and B 2 O 3 More preferably, it contains at least one selected from the above, and further preferably contains at least MgO.

[0015] The aluminosilicate hollow particles of the present invention are characterized by having a bulk density lower than that of conventional particles. Specifically, the bulk density of the aluminosilicate hollow particles of the present invention is 0.015 g / cm 3 Less than 0.013 g / cm is preferable. 3 Less than 0.012 g / cm is more preferable. 3 The lower limit of the bulk density is not particularly limited, but from the viewpoint of ensuring sufficient strength, it is preferably 0.0001 g / cm3 or less. 3 More than 0.0005 g / cm is preferable. 3 More preferably, 0.001 g / cm 3 In this specification, the term "bulk density" means "loose bulk density" and is measured in accordance with JIS R 1628-1997.

[0016] The aluminosilicate hollow particles of the present invention are characterized by a higher compression ratio than conventional ones. Specifically, the compression ratio of the aluminosilicate hollow particles of the present invention is preferably 85% or more, more preferably 86% or more, and even more preferably 87% or more. In addition, the upper limit of the degree of compression is preferably 97% or less, more preferably 95% or less, and even more preferably 93% or less, from the viewpoint of ensuring sufficient strength. Here, in this specification, "compressibility" refers to a value calculated by the following formula (1), and the "hardened bulk density" in the following formula (1) is measured in accordance with JIS R 1628-1997. In addition, for example, a tap density meter JV200i (manufactured by COPLEY) can be used to measure the loose bulk density and hardened bulk density.

[0017] Compression rate c(%)=(ρ p -ρ A ) / ρ p ×100 (1) [In the formula, ρ A indicates the loose bulk density, ρ p indicates the compacted bulk density.

[0018] The shape of the aluminosilicate hollow particles of the present invention is preferably non-spherical. By making the particles non-spherical, an increase in volume can be suppressed even if the bulk density is low, and therefore the labor and cost required for transportation can be reduced.

[0019] The fact that the particle shape of the aluminosilicate hollow particles of the present invention is non-spherical can be determined from the circularity. The circularity of the aluminosilicate hollow particles of the present invention is preferably 0.70 or less, more preferably 0.67 or less, and even more preferably 0.65 or less. When the circularity is 0.85 or more, it is usually determined to be substantially spherical. Here, in this specification, "circularity" refers to a value calculated by the following method. That is, when the projected area (A) and perimeter (PM) of a particle are measured from a scanning electron microscope photograph, and the area of ​​a perfect circle relative to the perimeter (PM) is (B), the circularity of the particle is expressed as A / B. Here, the perimeter and area of ​​a perfect circle having the same perimeter as the perimeter (PM) of the sample particle are expressed as PM=2πr and B=πr, respectively. 2Therefore, B = π × (PM / 2π) 2 The circularity of this particle is: Circularity = A / B = A × 4π / (PM) 2 The circularity of 100 particles is then measured, and the average value is taken as the "circularity" of the aluminosilicate hollow particles. In addition, the inorganic oxide hollow particles of the present invention preferably have a non-spherical particle shape, that is, the ratio of particles having a low circularity is a specific ratio. The ratio of particles having a low circularity is a specific ratio, which improves the compressibility. Specifically, when the circularity of the above 100 particles is measured, the ratio of particles having a circularity of 0.5 or less to the total particles is preferably 10% or more, more preferably 20% or more. This ratio may be 100% to the total particles.

[0020] The aluminosilicate hollow particles of the present invention preferably have an angle of repose of 50° or more, more preferably 52° or more, and even more preferably 54° or more. The upper limit of the angle of repose is not particularly limited, but from the viewpoint of improving handleability, it is preferably 70° or less, more preferably 65° or less, and even more preferably 60° or less. In this specification, the "angle of repose" is measured in accordance with ISO 902. For example, a Powder Tester PT-D type (manufactured by Hosokawa Powder Research Institute) can be used to measure the angle of repose.

[0021] The aluminosilicate hollow particles of the present invention are characterized by a large BET specific surface area. Specifically, the BET specific surface area of ​​the aluminosilicate hollow particles of the present invention is 15 m 2 / g or more is preferable, and 20m 2 / g or more is more preferable, and 25m 2 Although there is no particular upper limit to the BET specific surface area, from the viewpoint of increasing the amount of surface pores and decreasing the particle strength, it is preferable that the upper limit is 45 m 2 / g or less is preferable, and 40m 2 / g or less is more preferable, and 35m 2In this specification, the term "BET specific surface area" refers to a surface area measured by the BET method (a method for measuring surface area by utilizing the adsorption of gas molecules), and can be measured, for example, by using an automatic flow type specific surface area measuring device (FrowSorb III 2305, manufactured by Shimadzu Corporation).

[0022] The hollow ratio of the aluminosilicate hollow particles of the present invention is preferably 29% or more, more preferably 30% or more, and even more preferably 31% or more. The upper limit of the hollow ratio is preferably 95% or less, more preferably 90% or less, from the viewpoint of ensuring sufficient strength. Here, in this specification, the "hollow ratio" is a value calculated from the particle density and true density of the particles measured using a dry automatic densitometer using the following formula. Since it is difficult to measure each particle, it is the hollow ratio as a particle group. In addition, the "true density" is measured by heating the particles at or above the melting point for 6 hours in a box-type electric furnace in order to remove the hollow parts, cooling them, and measuring them with a dry automatic densitometer. For example, an Accupyc (Shimadzu Corporation) can be used as the dry automatic densitometer.

[0023] Hollowness ratio (%)=1-(particle density / true density)×100

[0024] The aluminosilicate hollow particles of the present invention are minute particles. More specifically, the particle size distribution can have the following characteristics. In this specification, the term "particle size distribution" refers to a volumetric particle size distribution measured in accordance with JIS R 1629 "Method for measuring particle size distribution of fine ceramic raw materials by laser diffraction and scattering method". The particle size distribution is represented by a distribution curve with the horizontal axis representing particle size (μm) and the vertical axis representing the volumetric frequency (%). For example, Microtrac (manufactured by Nikkiso Co., Ltd.) can be used as a particle size distribution measuring device using the laser diffraction and scattering method.

[0025] For example, the cumulative 10% particle size (D10) in the volume-based particle size distribution is preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.3 μm or more, and is preferably 3.0 μm or less, more preferably 2.5 μm or less, even more preferably 2.0 μm or less. The cumulative 50% particle size (D50) in the volume-based particle size distribution is preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and is preferably 7.0 μm or less, more preferably 6.0 μm or less, even more preferably 5.0 μm or less. The cumulative 90% particle size (D90) in the volume-based particle size distribution is preferably 5.0 μm or more, more preferably 7.0 μm or more, even more preferably 9.0 μm or more, and is preferably 20.0 μm or less, more preferably 15.0 μm or less, even more preferably 10.0 μm or less.

[0026] The aluminosilicate hollow particles of the present invention are preferably amorphous. The amorphous nature of the particles can be confirmed by analyzing the X-ray diffraction pattern obtained by an X-ray diffraction device. For example, Bruker D8 advance (manufactured by Bruker AXS Co., Ltd.) can be used as the X-ray diffraction device.

[0027] The aluminosilicate hollow particles of the present invention have the above-described characteristics and can be applied to various applications, such as heat insulating materials, heat shielding materials, soundproofing / absorbing materials, catalyst carriers, building materials, electronic materials, etc., and are useful as fillers for heat insulating materials, heat shielding materials, soundproofing / absorbing materials, building materials, electronic materials, etc., because of their low bulk density and high compressibility.

[0028] The method for producing the aluminosilicate hollow particles of the present invention is not particularly limited as long as it can produce aluminosilicate hollow particles having the above-mentioned configuration. For example, a method can be mentioned in which a liquid to be sprayed containing a raw material compound is sprayed from a spray device installed in a spray pyrolysis device, and the sprayed droplets (mist) are pyrolyzed.

[0029] Examples of the raw material compound include compounds containing silicon and aluminum as elements constituting an oxide. Such compounds are not particularly limited as long as they are compounds that dissolve in water, and examples include inorganic salts, organic salts, and alkoxides, and may contain one or more of these. Examples of inorganic salts include nitrates, sulfates, carbonates, hydroxides, and halides. Examples of organic salts include formates, acetates, propionates, oxalates, and citrates.

[0030] Examples of silicon-containing compounds include silicic acid alkoxides. Examples of silicic acid alkoxides include tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), tetrapropyl orthosilicate (TPOS), and tetrabutoxysilane. In addition, a solution in which silicon oxide is dispersed in a solvent, or a sol solution of silicon oxide can also be used as the raw material compound solution. Examples of aluminum-containing compounds include inorganic salts such as aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum phosphate, aluminum hydroxide, aluminum acetate, and aluminum oxalate, and aluminum alkoxides such as aluminum methoxide, aluminum ethoxide, and aluminum isopropoxide. In addition, aluminosilicates, solutions in which aluminum oxide is dispersed in a solvent, and sol solutions of aluminum oxide can also be used as the raw compound solutions. Examples of aluminosilicates include sodium aluminosilicate, potassium aluminosilicate, and calcium aluminosilicate.

[0031] In the present invention, the raw material compounds may further include compounds containing elements other than silicon and aluminum. Such a compound is not particularly limited as long as it is a metal compound that dissolves in water, and examples thereof include compounds containing one or more elements selected from Group 1 elements, Group 2 elements, boron, and Group 4 elements. Among them, compounds containing one or more elements selected from Group 2 elements and boron are preferred, compounds containing one or more elements selected from magnesium and boron are more preferred, and compounds containing at least magnesium are even more preferred. Examples of salts of these metals include inorganic salts, organic salts, and alkoxides. Specific examples of inorganic salts and organic salts are as described above, and examples of boron-containing compounds include metaborates such as sodium borate and potassium borate, tetraborates such as sodium tetraborate and potassium tetraborate, pentaborates such as sodium pentaborate and potassium pentaborate, and boric acid. Examples of magnesium-containing compounds include magnesium nitrate, magnesium sulfate, magnesium chloride, magnesium phosphate, and magnesium hydroxide.

[0032] Examples of oxides obtainable from these raw material compounds include silicon oxide, alumina, boron oxide, and magnesium oxide, as well as composite oxides that are combinations of these oxides.

[0033] The liquid to be sprayed can be prepared by mixing the raw material compounds with water or an organic solvent such as ethanol. The mixing ratio of the raw material compounds may be appropriately adjusted according to the type of the raw material compounds so as to obtain the aluminosilicate hollow particles having the above-mentioned composition.

[0034] The concentration of the raw material compounds in the liquid to be sprayed is preferably 0.01 mol / L to 2.0 mol / L, and more preferably 0.1 mol / L to 1.0 mol / L, in terms of the total amount of each element.

[0035] The spray pyrolysis apparatus preferably has a pyrolysis furnace with a vertical cylindrical shape, and the size of the pyrolysis furnace can be appropriately selected depending on the production scale.

[0036] Examples of the spraying device include fluid nozzles such as a two-fluid nozzle, a three-fluid nozzle, and a four-fluid nozzle. Here, the type of the fluid nozzle includes an internal mixing type in which the gas and the raw material solution are mixed inside the nozzle, and an external mixing type in which the gas and the raw material solution are mixed outside the nozzle, and either type can be adopted. As the gas to be supplied to the nozzle, for example, air, nitrogen, argon, or other inert gases can be used. Among them, air is preferable from the viewpoint of economy. Incidentally, one or more spraying devices can be installed.

[0037] The flow rate of the liquid to be sprayed is usually 1 to 100 L / h, preferably 3 to 80 L / h, and more preferably 5 to 60 L / h.

[0038] The droplets sprayed from the spray device are heated by a heater in the pyrolysis furnace to form a film containing an inorganic compound, and the film acts as a starting point for the formation of aluminosilicate hollow particles. The droplet ejection speed is usually 1 to 50 m / s, preferably 5 to 35 m / s, and more preferably 10 to 20 m / s.

[0039] Examples of the heating device include a combustion burner, a hot air heater, and an electric heater. One or more heating devices can be installed. Any of the combustion burners, hot air heaters, and electric heaters that are generally available on the market can be used. The temperature of the heating device is preferably 400 to 1800° C., more preferably 600 to 1500° C., further preferably 700 to 1400° C., and even more preferably 800 to 1200° C. At such a temperature, pyrolysis is sufficient, and the particles are less likely to aggregate when discharged outside the pyrolysis furnace.

[0040] The aluminosilicate hollow particles generated by the pyrolysis reaction are collected from the downstream side of the pyrolysis furnace using a powder collection device such as a high-performance cyclone powder collection machine or a bag filter. EXAMPLES

[0041] The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0042] 1. Chemical composition analysis The hollow aluminosilicate particles were pressed into briquettes, which were then analyzed using an X-ray fluorescence analyzer (ZSX primus II, manufactured by Rigaku Corporation) in terms of oxides to calculate the chemical composition. 2 , Al 2 O 3 MgO, B 2 Each chemical component was calculated by correcting it using the following formula so that the total value of 100% was 100%.

[0043] Chemical composition (after correction) (%) = Chemical composition (before correction) × 100 / (100-impurities (%)) (In the formula, the impurity (%) is calculated by subtracting the total value of the above-mentioned chemical composition of the oxide from 100.)

[0044] 2. Measurement of bulk density The measurement was performed using a tap density meter JV200i (manufactured by COPLEY) in accordance with JIS R 1628-1997.

[0045] 3. Compression ratio measurement The compression ratio was calculated according to the following formula (1).

[0046] Compressibility c(%)=(ρp-ρA) / ρp×100 (1) (In the formula, ρA represents the loose bulk density, and ρp represents the hard bulk density.)

[0047] 4. Measurement of particle density, true density, and hollowness The particle density and true density of the particles were measured using an Accupyc (Shimadzu Corporation) as a dry automatic density meter, and calculated using the following formula: Note that the true density was measured by heating the particles at or above the melting point for 6 hours in a box-type electric furnace to remove hollow parts, then cooling and measuring the true density with the dry automatic density meter.

[0048] Hollowness ratio (%)=(1-particle density / true density)×100

[0049] 5. Measurement of angle of repose The measurements were performed using a Powder Tester PT-D model (manufactured by Hosokawa Powder Laboratory Co., Ltd.) in accordance with ISO 902.

[0050] 6. Measurement of circularity When the projected area (A) and perimeter (PM) of a particle are measured from a scanning electron microscope photograph, and the area of ​​a perfect circle relative to the perimeter (PM) is (B), the circularity of the particle is expressed as A / B. Here, the perimeter and area of ​​a perfect circle with the same perimeter as the perimeter (PM) of the sample particle are PM=2πr and B=πr, respectively. 2 Therefore, B = π × (PM / 2π) 2 The circularity of this particle is: Circularity = A / B = A × 4π / (PM) 2 The circularity was calculated as follows. The circularity of 100 particles was measured, and the average value was taken as the "circularity" of the aluminosilicate hollow particles. The percentage of particles with a circularity of 0.5 or less was also calculated. The scanning electron microscope used was JSM-7001F (manufactured by JEOL Ltd.).

[0051] 7. Crystal Structure Analysis Measurements were performed using a powder X-ray diffractometer (Bruker D8 advance, manufactured by Bruker AXS Co., Ltd.), and the crystal structure was analyzed from the obtained X-ray diffraction pattern.

[0052] 8. Particle size measurement A particle size distribution was prepared based on volume in accordance with JIS R 1629 using a particle size distribution measuring device (MT3000II, manufactured by Microtrack Bell), and the cumulative 10% particle size (D10) in the volume-based particle size distribution, the cumulative 50% particle size (D50) in the volume-based particle size distribution, and the cumulative 90% particle size (D90) in the volume-based particle size distribution were determined.

[0053] 9. Measurement of BET specific surface area The BET specific surface area was measured using an automatic flow type specific surface area measuring device (FlowSorb III 2305, Shimadzu Corporation) using a nitrogen-helium gas mixture containing 30% nitrogen.

[0054] Examples 1 to 3 and Comparative Example 1 The raw material compounds (colloidal silica, tetraethyl orthosilicate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and boric acid) were dissolved in 30 liters of distilled water to the molar concentrations shown in Table 1, and the raw material compound aqueous solution was charged into a solution tank. The charged aqueous solution was sent to a two-fluid nozzle by a liquid delivery pump, sprayed in a mist form from the two-fluid nozzle, and heated in a furnace (1000°C). The operating conditions of the two-fluid nozzle were set to a nozzle air volume of 100 L / min and a liquid delivery volume of 67 mL / min. Then, the mixture was quenched by a cooling mechanism installed at the outlet of the reaction zone of the furnace, and the aluminosilicate hollow particles were then collected using a bag filter. The physical properties of the collected aluminosilicate hollow particles were analyzed. The results are shown in Table 2.

[0055] [Table 1]

[0056] [Table 2]

[0057] It can be seen that the aluminosilicate hollow particles of Examples 1 to 3 have a lower bulk density and a higher compression ratio than the aluminosilicate hollow particles of Comparative Example 1. It can also be seen that the aluminosilicate hollow particles of Examples 1 to 3 differ in shape from the aluminosilicate hollow particles of Comparative Example 1 in that they are non-spherical, and have a larger angle of repose and BET specific surface area than the aluminosilicate hollow particles of Comparative Example 1.

Claims

1. Bulk density is 0.015 g / cm 3 The aluminosilicate hollow particles have a compressibility of 85% or more, The total content of SiO 2 and Al 2 O 3 is 70 mass% or more, the mass ratio of SiO 2 to Al 2 O 3 (Al 2 O 3 / SiO 2 ) is 0.2 to 0.3; The SiO 2 content is 60% by mass or more and 80% by mass or less, The content of Al 2 O 3 is 15 mass % or more and 25 mass % or less, The content of boron oxide is 20% by mass or less, The content of the second element oxide is 0.5% by mass or more and 12% by mass or less. Aluminosilicate hollow particles.

2. 2. The aluminosilicate hollow particles according to claim 1, having a circularity of 0.70 or less.

3. 3. The aluminosilicate hollow particles according to claim 1 or 2, which have an angle of repose of 50° or more.

4. BET specific surface area is 15m 2 The aluminosilicate hollow particles according to any one of claims 1 to 3, wherein the aluminosilicate hollow particles have a molecular weight of 1 / g or more.

5. 5. The inorganic oxide hollow particles according to claim 1, wherein the proportion of particles having a circularity of 0.5 or less is 10% or more of the total particles.

Images