Aluminosilicate granules and powder

Abstract

To provide a powder having a novel structure not found in the past. SOLUTION: Aluminosilicate granules containing nanotube-shaped particles and having pores with a diameter of more than 200 nm.

Description

[Technical Field]

[0001] The present invention relates to aluminosilicate granules. The present invention also relates to a powder comprising aluminosilicate granules. [Background technology]

[0002] Patent Document 1 discloses a powder containing granules formed by aggregation of halloysite containing halloysite nanotubes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 079556 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide aluminosilicate granules having a novel structure that has not been found conventionally. The present invention also aims to provide a powder. [Means for solving the problem]

[0005] As a result of extensive research to achieve the above object, the present inventors discovered granules having pores with a pore size of more than 200 nm, and completed the present invention.

[0006] That is, the present invention provides the following [1] to [8]. [1] Aluminosilicate granules containing nanotube particles and having pores with a diameter of more than 200 nm. [2] The aluminosilicate granules according to [1], further having pores of more than 8 nm and not more than 200 nm. [3] The aluminosilicate granules according to [2], which have, as the pores, first pores derived from the nanotube particles and second pores different from the first pores. [4] The aluminosilicate granules according to any one of [1] to [3], further having pores with a pore size of 8 nm or less. [5] The aluminosilicate granules according to any one of [1] to [4], having first pores derived from the nanotube particles and having a pore size of more than 8 nm and not more than 200 nm, second pores different from the first pores and having a pore size of more than 8 nm and not more than 200 nm, and third pores having a pore size of not more than 8 nm. [6] The aluminosilicate granules according to any one of [1] to [5], wherein the nanotube particles are nanotube aluminosilicate particles. [7] The aluminosilicate granules according to any one of [1] to [6], wherein the nanotube particles include particles derived from halloysite nanotubes. [8] A powder containing the aluminosilicate granules according to any one of [1] to [7]. [Effects of the Invention]

[0007] According to the present invention, aluminosilicate granules having a novel structure can be provided. The present invention also provides a powder. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an SEM image of granules contained in Powder 1 of an example. [Figure 2] 1 is an SEM image of granules contained in Powder 1 of an example. [Figure 3] 1 shows the pore size distribution of Powder 1 of the example. [Figure 4] 1 is a graph showing the transition of viable cell counts in an antibacterial test. [Figure 5] 1 is an SEM image of granules contained in Powder 2 of Comparative Example. [Figure 6] 1 is an SEM image of granules contained in Powder 2 of Comparative Example. [Figure 7] 1 shows the pore size distribution of Example Powder 3A. [Figure 8]1 is an SEM image of granules contained in Powder 3 of the example. [Figure 9] 1 is an SEM image of granules contained in Powder 3 of the example. [Figure 10] 1 is an SEM image of granules contained in Powder 3A of the example. [Figure 11] 1 is an SEM image of granules contained in Powder 3A of the example. [Figure 12] 1 is an SEM image of granules contained in Powder 4A of the example. [Figure 13] 1 is an SEM image of granules contained in Powder 4A of the example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0010] [Aluminosilicate Granules] The aluminosilicate granules of the present invention contain nanotube particles and have pores with diameters of more than 200 nm. Hereinafter, pores with diameters of more than 200 nm are also referred to as "coarse pores." The aluminosilicate granules preferably contain nanotube particles as primary particles. The aluminosilicate granules are not particularly limited as long as they contain nanotube particles, and may contain other particles. The content of nanotube particles in the aluminosilicate granules is preferably 70 mass% or more, more preferably 80 mass% or more, and even more preferably 90 mass% or more, based on the total mass of the aluminosilicate granules. The upper limit of the content of nanotube particles is not particularly limited, and may be 100 mass% based on the total mass of the aluminosilicate granules. In other words, the aluminosilicate granules may be granules formed by aggregation of nanotube particles.

[0011] The shape of the aluminosilicate granules of the present invention is not particularly limited, and examples thereof include spherical, hemispherical, spheroidal, ellipsoidal, plate-like, nodular, cylindrical, and polygonal prism-like shapes. The shape of the aluminosilicate granules of the present invention may also be irregular. The particle size of the aluminosilicate granules of the present invention is not particularly limited and may be appropriately selected depending on the application, but is, for example, 0.5 to 200 μm, preferably 1 to 100 μm. In this specification, the particle size of the aluminosilicate granules refers to the maximum size of the aluminosilicate granules, and is obtained by analyzing an image obtained by observing with a scanning electron microscope (SEM). In this specification, SEM observations are performed using a Sigma 500 manufactured by Carl Zeiss Microscopy Ltd. When observing aluminosilicate granules using SEM, a powder containing the aluminosilicate granules of the present invention is attached to the adhesive surface of carbon tape, and an observation sample is used that has been conductively coated.

[0012] In the aluminosilicate granules of the present invention, the molar ratio of the SiO2 content to the Al2O3 content (hereinafter simply referred to as "SiO2 / Al2O3") is not particularly limited, but is preferably 1.8 or more. It is also preferable that SiO2 / Al2O3 is 2.1 or more, and it may be 3.0 or more, or even 5.0 or more. The upper limit of SiO2 / Al2O3 is not particularly limited, and examples include 10,000 or less and 1,000 or less, preferably 500 or less, more preferably 300 or less, and even more preferably 200 or less. The SiO2 / Al2O3 ratio is determined by X-ray fluorescence (XRF) analysis, using a powder containing the aluminosilicate granules of the present invention. The SiO2 / Al2O3 ratio obtained by measuring the powder is considered to be the SiO2 / Al2O3 ratio of the aluminosilicate granules of the present invention. Specifically, XRF analysis is performed under the following conditions to determine SiO2 / Al2O3. Equipment used: ZSX Primus IV (Rigaku Corporation) Pretreatment method: Glass bead method using Li2B4O7 flux Quantitative method: Refractories Technology Association standard sample for X-ray fluorescence analysis (clay brick standard sample series) and calibration curve method using other reagents

[0013] The nanotube particles contained in the aluminosilicate granules will be described below.

[0014] <Nanotube particles> The nanotube particles are not particularly limited, but are preferably nanotube particles containing an alumina component and a silica component, and more preferably nanotube aluminosilicate particles. The nanotube particles preferably contain particles derived from halloysite nanotubes, which will be described later. The aluminosilicate granules may contain two or more types of nanotube particles.

[0015] Halloysite is a clay mineral expressed as Al2Si2O5(OH)4·2H2O or Al2Si2O5(OH)4. In other words, the SiO2 / Al2O3 ratio in halloysite is generally 2.0. Halloysite generally exhibits a variety of shapes, such as tubular (hollow tubular), spherical, angular nodular, plate-like, and sheet-like shapes. The inner diameter (diameter of the tube pore) of a halloysite nanotube, which is a tubular (hollow tubular) halloysite, is, for example, about 10 to 20 nm. It is generally said that the outer surface of a halloysite nanotube particle is mainly made of silicate (SiO2) and the inner surface is mainly made of alumina (Al2O3).

[0016] In addition, particles derived from halloysite nanotubes are a concept that includes halloysite nanotube particles and particles obtained by subjecting halloysite nanotube particles to the treatment described below (hereinafter also referred to as "modified halloysite nanotube particles"). Examples of modified halloysite nanotube particles include metahalloysite nanotube particles obtained by calcining halloysite, and acid-treated metahalloysite nanotube particles obtained by subjecting metahalloysite nanotube particles to an acid treatment. The aluminosilicate granules may contain only halloysite nanotube particles, only modified halloysite nanotube particles, or both halloysite nanotube particles and modified halloysite nanotube particles. Alternatively, the aluminosilicate granules may contain two or more types of modified halloysite nanotube particles.

[0017] The metahalloysite nanotube particles that may be contained in the above-mentioned aluminosilicate granules refer to nanotube-shaped halloysite in which the OH of halloysite represented by Al2Si2O5(OH)4 has been dehydrated, resulting in a low crystallinity, and metahalloysite is a term that has traditionally been used generally or customarily to represent a variant of halloysite. The metahalloysite nanotube particles are obtained by firing the halloysite nanotube particles at a predetermined temperature. The predetermined temperature is preferably 500°C or higher, more preferably 600°C or higher. The upper limit of the predetermined temperature is preferably 925°C or lower, more preferably 900°C or lower.

[0018] The acid-treated metahalloysite nanotube particles that can be contained in the above-mentioned aluminosilicate granules are obtained by subjecting metahalloysite nanotube particles to an acid treatment. The acid treatment refers to a treatment in which the metahalloysite nanotube particles are brought into contact with an acidic treatment solution. The acid treatment leaches Al2O3 in the metahalloysite nanotube particles. Acid-treated metahalloysite nanotube particles often have pores with a diameter of 8 nm or less, and have unique adsorption properties derived from these pores. The acid-treated metahalloysite nanotube particles may be those which have been subjected to a calcination treatment after the acid treatment.

[0019] The characteristics of the aluminosilicate granules of the present invention will be described below.

[0020] <Coarse hole> The aluminosilicate granules of the present invention have pores with a pore size of more than 200 nm (coarse pores). The presence or absence of coarse pores can be confirmed by observing the surface of the aluminosilicate granules with an SEM (see Figure 1). In this specification, the pore diameter of the coarse pores refers to the diameter of the pores that can be observed from the surface when the surface of the aluminosilicate granules is observed with an SEM. When the shape of the observed pores is not a perfect circle, the major axis of the longest distance between two parallel lines tangent to the shape of the pore is taken as the pore diameter of the coarse pore. The shape of the coarse pores observed with an SEM is not particularly limited, and may be circular, elliptical, or another shape. Furthermore, when the distance between two parallel lines tangent to the shape of a pore is the shortest, the ratio of the pore diameter (long diameter) of the coarse pore to the short diameter is preferably 50 or less, more preferably 20 or less, and may be 10 or less, 5 or less, or 2 or less. The ratio of the pore diameter (long diameter) of the coarse pore to the short diameter may be 1.

[0021] The pore size of the coarse pores is preferably 0.3 μm or more, more preferably 0.5 μm or more. There is no particular upper limit to the pore size of the coarse pores, but it is often 10 μm or less, preferably 5 μm or less. The pore size of the coarse pores is often 99% or less, preferably 90% or less, or may be 70% or less of the diameter (maximum diameter) of the aluminosilicate granules. The pore size of the coarse pores is often 1% or more, but may be 5% or more, 10% or more, or 30% or more of the diameter (maximum diameter) of the aluminosilicate granules.

[0022] In the present invention, one aluminosilicate granule may have only one coarse pore or may have multiple coarse pores, and the coarse pores may be interconnected or independent within the aluminosilicate granule. The diameter and structure of the coarse pores can be adjusted by the procedure in the powder production method described later. Furthermore, when the aluminosilicate granule has a plurality of coarse pores, the pore size of the coarse pore refers to the pore size of the largest coarse pore.

[0023] Pores with a diameter of more than 200 nm (coarse pores) allow for the adsorption of large objects, which is thought to contribute to the promotion of adsorption and reaction of solid substances. For example, the presence of coarse pores makes it possible to capture dust, viruses, bacteria, pollen, etc. and react with them (e.g., inactivate them). Furthermore, pores with a diameter of more than 200 nm have excellent mass transfer properties and can promote mass transfer when applied to various applications. For example, the aluminosilicate granules of the present invention have excellent mass transfer properties when used as catalysts, catalyst carriers, adsorbents, sustained-release materials, etc.

[0024] <pores> The aluminosilicate granules of the present invention preferably have fine pores other than the above-mentioned coarse pores. The pores preferably have a pore diameter of more than 8 nm and not more than 200 nm, and more preferably more than 8 nm and not more than 100 nm. The presence or absence of pores can be confirmed by measuring an adsorption isotherm. Specifically, a nitrogen adsorption isotherm of a powder containing the aluminosilicate granules of the present invention is obtained, and the nitrogen adsorption isotherm is analyzed using the BJH (Barrett-Joyner-Halenda) method. A plot (Log differential pore volume distribution) is created with pore diameter on the horizontal axis and differential pore volume on the vertical axis, thereby confirming the presence or absence of pores in the above pore diameter range. The measurement conditions for obtaining the nitrogen adsorption isotherm will be described in detail in the Examples section below. The same applies to the other measurement conditions below.

[0025] The aluminosilicate granules of the present invention preferably have first pores derived from the nanotube particles and second pores different from the first pores. The first pores preferably correspond to the tube pores of the nanotube particles. The second pores preferably correspond to the interparticle voids of the nanotube particles contained in the aluminosilicate granules. The pore diameters of the first pores and the second pores are preferably both in the range of more than 8 nm to 200 nm, more preferably both in the range of more than 8 nm to 100 nm, and even more preferably both in the range of 10 to 50 nm. The first pores are preferably in the range of 10 to 20 nm. It is also preferable that the Log differential pore volume distribution analyzed by the BJH method shows two or more pore diameter peaks in the above range. The presence or absence of pores with a pore diameter of more than 8 nm and not more than 200 nm (more preferably pores with a pore diameter of more than 8 nm and not more than 100 nm), and the presence or absence of first pores and second pores can also be confirmed by observing the aluminosilicate granules with an SEM. When the surface of the aluminosilicate granules is observed with an SEM, the presence of first pores derived from the tubular structure of the nanotube particles can be confirmed, and when the cross section of the aluminosilicate granules is observed with an SEM, the presence of second pores can be confirmed. For example, the cross section of the aluminosilicate granules can be observed by cutting the aluminosilicate granules with a focused ion beam (FIB) to obtain a sample and then observing the sample.

[0026] The aluminosilicate granules of the present invention may have third pores having a pore size of 8 nm or less, different from the first pores and the second pores. The aluminosilicate granules of the present invention may have the third pores having a pore size of 8 nm or less together with the pores having a pore size of more than 8 nm and less than 200 nm. Furthermore, the aluminosilicate granules of the present invention may have the first pores having a pore size of more than 8 nm and less than 200 nm, the second pores having a pore size of more than 8 nm and less than 200 nm, and the third pores having a pore size of 8 nm or less. The presence or absence of third pores with a pore size of 8 nm or less can be confirmed by performing a so-called t-plot analysis of the nitrogen adsorption isotherm of a powder containing the aluminosilicate granules of the present invention to confirm the presence or absence of micropores with a size of less than 2 nm, or by fitting the nitrogen adsorption isotherm using the GCMC (Grand Canonical Monte Carlo) method to obtain a pore size distribution. The third pores having a pore size of 8 nm or less are present in, for example, acid-treated metahalloysite nanotube particles, so that when aluminosilicate granules contain acid-treated metahalloysite nanotube particles, the aluminosilicate granules have third pores having a pore size of 8 nm or less. Note that general halloysite nanotube particles do not have third pores having a pore size of 8 nm or less. The third pores having a pore diameter of 8 nm or less are preferably, for example, 0.6 to 5 nm. The third pores having a pore diameter of 8 nm or less may have multiple peaks in the pore diameter range of 8 nm or less in the pore diameter distribution obtained by the above method.

[0027] The third pores having a pore size of 8 nm or less are nano-spaces in a range close to the molecular size, and therefore can function as specific reaction sites and specific adsorption sites for molecules. When the aluminosilicate granules have third pores having a pore size of 8 nm or less, the aluminosilicate granules of the present invention can be suitably used as, for example, a catalyst, a catalyst support, an adsorbent, etc.

[0028] Furthermore, pores with a pore diameter of more than 8 nm and not more than 200 nm are thought to have superior mass transfer properties compared to the third pores with a pore diameter of 8 nm or less, contributing to rapid reaction and adsorption, and can be used, for example, in applications similar to those described above. Furthermore, the inclusion of the third pores with a pore diameter of 8 nm or less is thought to enable even better performance. The first pores are thought to originate from the pores of the nanotube particles and have a tubular structure of a predetermined length, and are therefore expected to function as shape-selective catalysts that selectively act on the shape of molecules, etc. In addition, albumin can be placed in the pores in the above region to impart catalytic activity, which can be used to synthesize pharmaceuticals and the like. Furthermore, the pores in the above region can cause molecular adsorption accompanied by liquefaction due to capillary condensation, and can exhibit a large amount of adsorption, so they can also function as an adsorbent (e.g., a moisture-absorbing material) that repeatedly adsorbs and desorbs, as well as a sustained-release material.

[0029] Furthermore, the aluminosilicate granules of the present invention may simultaneously have third pores with a pore size of 8 nm or less and pores with a pore size of more than 8 nm and less than 200 nm, and may also have pores with a pore size of more than 200 nm. The aluminosilicate granules of the present invention having both of the above-mentioned pores have a novel multimodal nanospace structure, and such a nanospace structure is expected to promote unexplored chemical reactions and has the potential to open up new technologies in fields such as the environment, energy, food, and pharmaceuticals.

[0030] The advantages of having the above-mentioned pores are merely examples, and it goes without saying that the aluminosilicate of the present invention can be used in general applications as a porous material. The formation of each of the above pores and the adjustment of each of the pores can be controlled by the procedure and conditions of the manufacturing method described later.

[0031] <Other components and other particles> The aluminosilicate granules of the present invention may contain components other than the nanotube particles. For example, the aluminosilicate granules may contain a catalytic component that promotes a desired reaction. The catalytic component may be supported on the aluminosilicate granules or nanotubular particles as particles, or as clusters of single atoms or several atoms. The catalytic component may also be supported on the aluminosilicate granules and nanotubular particles. The elements contained in the catalyst component are not particularly limited and can be selected depending on the desired reaction. Examples of elements contained in the catalyst component include Group 1 elements to Group 17 elements, and often contain transition metal elements or rare earth elements. The type of element contained in the catalyst component may be one type, or two or more types. The above-mentioned catalyst component is a concept that includes not only a catalyst component that promotes the desired reaction, but also so-called co-catalysts that promote the progress of the desired reaction. Known catalyst components can be used, and known methods can be appropriately used to support the catalyst components.

[0032] In the powder of the present invention, the aluminosilicate granules may contain a medicinal component as a component other than the nanotube particles. The medicinal component is not particularly limited, and examples thereof include known deodorant components, antibacterial components, bactericidal components, and pharmaceutical components.

[0033] The aluminosilicate granules may also contain particles other than nanotube particles (other particles). The other particles are not particularly limited, but examples thereof include magnetic particles, colorant particles, drug particles, etc. When the aluminosilicate granules contain magnetic particles, the aluminosilicate granules can be separated from the dispersion liquid by magnetic force.

[0034] <Characteristics of powder> The aluminosilicate granules also preferably have a breaking strength of 3 MPa or more. When the aluminosilicate granules of the present invention have the above breaking strength, the coarse pores and the second pores are particularly likely to be maintained. Therefore, when the aluminosilicate granules of the present invention have the above breaking strength, they are less likely to be broken and the pores can be maintained during handling of a powder containing the aluminosilicate granules of the present invention, during pretreatment (e.g., dispersion treatment), and during composite treatment (e.g., kneading with a resin). On the other hand, common porous materials such as silica gel, mesoporous silica, and activated carbon often have low particle breaking strength, and the particles may be broken during the above-mentioned operations, making it impossible to maintain the pore structure. The breaking strength is more preferably 4 MPa or more, and even more preferably 5 MPa or more. The upper limit of the breaking strength is not particularly limited, and is, for example, 60 MPa or less, preferably 50 MPa or less, and more preferably 45 MPa or less.

[0035] The breaking strength of the aluminosilicate granules of the present invention is measured by a compression test using a microcompression tester, and is the average value of five test results. More specifically, the aluminosilicate granules of the present invention are first used as a sample. A very small amount of this sample is scattered on the sample stage (lower pressure plate) of a microcompression tester MCT-510 (manufactured by Shimadzu Corporation), and a compression test is performed on each sample particle to determine its breaking strength. Typically, the average value of five test results (breaking strength) is used as the breaking strength of the powder. The breaking strength is calculated by measuring the diameters of each sample particle in the X and Y directions on the sample stage, taking the average value as the particle size of each sample particle, and using the following formula (1). (1) Cs = 2.48 × P / (πd 2 ) In equation (1), Cs is the breaking strength (unit: MPa), P is the breaking test force (unit: N), and d is the diameter of the sample particle (unit: mm).

[0036] It is also preferable that the hydrated breaking strength of the aluminosilicate granules hydrated by immersion in pure water for 24 hours is 80% or more of the above-mentioned breaking strength. The hydrated breaking strength may be the same value as the above-mentioned breaking strength, i.e., 100%. When the hydrated breaking strength is excellent, the pore structure is easily maintained even in applications where the granules come into contact with aqueous solutions, etc., which is preferable. The wet breaking strength is measured in the same manner as in the above method for measuring breaking strength, except that the sample is aluminosilicate granules that have been immersed in pure water for 24 hours to become wet.

[0037] [Powder] The powder of the present invention comprises the aluminosilicate granules of the present invention described above. It is also preferable that when an observation sample of the powder of the present invention is obtained by the above-described method and observed by SEM to obtain an observation image, the proportion of aluminosilicate granules having coarse pores is 1% or more. The proportion of the number of aluminosilicate granules having coarse pores may be 5% or more, 10% or more, or even 50% or more. The proportion of the number of aluminosilicate granules having coarse pores may be 100% or less, 90% or less, or 70% or less. The proportion of the aluminosilicate granules having the coarse pores is calculated by the following procedure. First, in the observation image, the number of particles whose overall shape can be confirmed and whose overall shape can be adequately estimated is counted. The number of particles counted is 200 or more. If the number of counted particles in one observation image is less than 200, the same particle count is repeated in observation images acquired in other fields of view until the number of counted particles reaches 200 or more. In this case, the ratio of the number of particles in which coarse pores are found among the counted particles is taken as the ratio of the number of aluminosilicate granules having coarse pores. The proportion of the number of aluminosilicate granules having coarse pores calculated by the above method can be adjusted, for example, by the conditions of the production method described later.

[0038] The content of the aluminosilicate granules is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more, based on the total mass of the powder of the present invention. It may be 10% by mass or more, 50% by mass or more, 80% by mass or more, 90% by mass or more, or even 95% by mass or more. The upper limit of the content of the aluminosilicate granules in the powder of the present invention is not particularly limited, and may be 100% by mass based on the total mass of the powder. That is, the powder of the present invention may consist of the aluminosilicate granules of the present invention. The powder of the present invention may also contain aluminosilicate granules that do not have coarse pores. When the powder of the present invention contains aluminosilicate granules that do not have coarse pores, the content of the aluminosilicate granules that have coarse pores is preferably 1% by mass or more, more preferably 5% by mass or more, and may be 10% by mass or more, 50% by mass or more, or even 70% by mass or more, based on the total mass of the aluminosilicate contained in the powder of the present invention. The upper limit of the content of the aluminosilicate granules that have coarse pores in the powder of the present invention is not particularly limited, and may be 100% by mass based on the total mass of the powder. In other words, the powder of the present invention may be composed of aluminosilicate granules that have coarse pores.

[0039] The characteristics of the powder of the present invention will be described below.

[0040] <Specific surface area> The specific surface area (BET specific surface area) of the powder of the present invention is 30 m 2 / g or more is preferable, and 50m 2 / g or more is more preferable. In addition, the BET specific surface area is 80m 2 The upper limit of the BET specific surface area is not particularly limited, but may be, for example, 1000 m 2 / g or less, and 600m 2 / g or less. The BET specific surface area is 200m 2 / g or less. The BET specific surface area can be determined by applying the BET method to a nitrogen adsorption isotherm.

[0041] <Pore volume> The total pore volume of the powder of the present invention is 0.20 cm 3 / g or more is preferable, and 0.23 cm 3 / g or more is more preferable. The total pore volume is 0.45 cm 3 The upper limit of the total pore volume is not particularly limited, but may be, for example, 2.00 cm 3 / g or less, 1.20cm 3 / g or less. The total pore volume is usually 0.80 cm 3 / g or less. The total pore volume is calculated from the adsorption amount at a relative pressure of 0.99 from the nitrogen adsorption isotherm using the following formula: Vp=V / 22414×Mg / ρg Vp: total pore volume up to relative pressure (0.99) V: Adsorption amount at relative pressure (0.99) 22414:Volume of gas per mole Mg: Molecular weight of adsorbate (N2) (28.013) ρg: Density of adsorbate (N2) (0.808)

[0042] In addition, when the powder of the present invention has micropores (less than 2 nm), the volume of the micropores is less than 0.01 cm 3 / g or more is preferable, and 0.02 cm 3 / g or more is more preferable, and 0.04cm 3 / g or more is more preferable, and 0.08 cm 3 The upper limit of the volume of the micropores is not particularly limited, but for example, it is 0.5 cm 3 / g or less, and 0.2cm 3 / g or less in most cases.

[0043] <Characteristics of powder> The average particle size of the powder of the present invention is not particularly limited and may be appropriately selected depending on the application, but is, for example, 0.5 to 200 μm, preferably 1 to 100 μm. The powder of the present invention may be granulated before use. The size of the granulated powder is preferably 5 mm or less. The average particle size is measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII) manufactured by Microtrac Bell.

[0044] [Powder uses] The powder of the present invention can be preferably used, for example, as an adsorbent. Furthermore, the powder of the present invention is not limited to use as an adsorbent, but can be used in a wide variety of applications. Examples of applications include catalysts, catalyst carriers, humidity conditioners, sustained-release materials, cosmetics, coloring materials, precision polishing particles, magnetic materials, deodorizing agents, antibacterial agents, water purification agents, coloring materials, food, fermentation, pharmaceuticals, and artificial enzymes, but needless to say, the applications are not limited to these. The powder of the present invention is also suitable as a filler that imparts properties such as light weight, heat insulation or sound absorption, and as a coating material.

[0045] [Powder manufacturing method] A method for producing the powder of the present invention (hereinafter, for convenience, also referred to as the "production method of the present invention") will be described. According to the production method of the present invention, a powder containing the above-mentioned aluminosilicate granules of the present invention can be obtained. The manufacturing method of the present invention preferably includes at least a step of preparing a slurry containing nanotube-shaped particles and template particles (described later) (slurry preparation step), a step of preparing a template-containing powder from the slurry (powder preparation step), and a step of removing the template particles from the template-containing powder, thereby obtaining a powder containing aluminosilicate granules formed by aggregation of nanotube-shaped particles and having coarse pores. Hereinafter, a preferred embodiment of the production method of the present invention in which the nanotube particles include halloysite nanotube particles will be described.

[0046] <Slurry preparation process> (Raw material (halloysite)) As the halloysite (hereinafter also referred to as "raw halloysite") used as the raw material in the manufacturing method of the present invention, commercially available halloysite (halloysite nanotubes) can be used, and specifically, for example, halloysite manufactured by APPLIED MINERALS (product name: DRAGONITE-HP) can be suitably mentioned.

[0047] (Slurrying) First, a slurry in which the raw halloysite is dispersed in water is obtained. The method for dispersing the raw halloysite in water is not particularly limited, and a conventionally known device such as a high-speed mixer, a disperser, a bead mill, or a homomixer can be used. The solid content concentration of the slurry is not particularly limited and is, for example, 30 to 50 mass %.

[0048] It is preferable to add a dispersant to the slurry because it is closely related to the accuracy of centrifugation described later. By adding a dispersant, a slurry with a higher concentration can be obtained, which also has the effect of improving productivity in drying using a spray dryer or the like described later.

[0049] The dispersant is preferably one that can provide a stable slurry with a small amount of use, and examples thereof include polymeric anionic surfactants (anionic polymeric surfactants). Specific examples of anionic polymer surfactants include special polycarboxylic acid type Poise 520, 521, and 530 (all manufactured by Kao Corporation). Depending on the intended use, Poise 532A, Caocera 2000, 2020 and 2110 (same), which do not contain metal ions such as sodium and potassium, can also be used. Furthermore, the anionic polymer surfactant is not limited to polycarboxylic acid types, and acrylic acid types, sulfonic acid types, etc. may also be used.

[0050] The content of the dispersant is not particularly limited, but a suitable example is 0.5 to 3.0 mass % relative to the total solid content in the slurry. If the dispersant content is too low, the halloysite and impurity particles may not be dispersed sufficiently in the slurry. On the other hand, if the dispersant content is too high, agglomeration may occur and costs may increase. Furthermore, problems in downstream processes (such as reduced recovery of the dispersed phase during centrifugation, insufficient drying during spray drying, or insufficient caking or burning during firing) may be more likely to occur.

[0051] (coarse grain removal) To improve the accuracy of the centrifugal separation described below, coarse particles may be removed from the slurry. For example, a sieve with openings of 25 to 100 μm, a wet cyclone, or the like may be used to remove the coarse particles. Alternatively, the coarse particles may be removed by allowing the slurry to settle naturally.

[0052] (Centrifugation) The obtained slurry is centrifuged to separate it into a lower sedimentation phase and an upper dispersed phase. The sedimentation phase contains many impurities such as fine sand, while the dispersed phase contains many halloysite nanotube particles. The solids concentration of the dispersed phase (slurry) is, for example, 10 to 30 mass%. The centrifugal force and processing time during centrifugation are, for example, 2000 to 3000 G and 3 to 30 minutes, respectively, but are not limited to these and are set appropriately taking into consideration the dispersion state, application, cost, and the like. Larger centrifuges can also be used for mass production. By recovering the dispersed phase, halloysite nanotube particles can be purified and separated from raw halloysite containing impurities such as fine sand.

[0053] (Addition of template particles) Template particles are added to the collected dispersed phase (slurry). The amount of addition is, for example, but not limited to, such that the content of template particles in the slurry after addition is 2 to 50 mass % relative to the total amount of halloysite nanotube particles and template particles in the slurry. After the addition, the template particles are dispersed in the slurry by any method, and for example, a conventionally known device such as a high-speed mixer, a disperser, a bead mill, or a homomixer can be used. The slurry obtained in the slurry preparation step may be subjected to purification, classification, magnetic separation, concentration, and other procedures, as required.

[0054] The template particles are composed of a material that is removable in a template removal step. Examples of template particles include resin particles and carbon particles, which can be removed by a baking treatment described below, as well as magnesium oxide particles, calcium carbonate particles, and zinc oxide particles, which can be removed by an acid treatment described below. The template particles are not limited to the above examples, and may be any particles that can be removed in the template removal step.

[0055] The particle size and shape of the template particles can be appropriately selected depending on the desired pore size and shape of the coarse pores. The content of template particles in the slurry can be appropriately adjusted depending on the desired number of coarse pores. The shape of the template particle may be, for example, spherical, tabular, rod-like, polygonal pyramidal, etc. The particle diameter of the template particle may be, for example, more than 0.1 μm and not more than 5 μm, and may be more than 0.2 μm and not more than 5 μm. Only one type of template particle may be used, or two or more types may be used.

[0056] The template particles may be subjected to a surface treatment to control dispersibility in the slurry, for example, a hydrophilic treatment or a hydrophobic treatment. By subjecting the template particles to a surface treatment, the distribution of template particles in the granules obtained in the powder preparation step described below can be changed, thereby making it possible to control the shape and distribution of coarse pores in the final powder (aluminosilicate granules) obtained.

[0057] <Powder preparation process> The powder preparation step is a step of preparing a template-containing powder from the slurry prepared in the slurry preparation step. The template-containing powder includes aluminosilicate granules containing template particles and halloysite nanotube particles. The mold-containing powder obtained in the powder preparation step may be further granulated by rolling, stirring, extrusion, etc. This allows the size of the granules constituting the mold-containing powder to be increased.

[0058] (Spray drying) The powder preparation step may, for example, be a step of spray-drying the slurry prepared in the slurry preparation step to obtain a mold-containing powder.

[0059] To spray-dry the prepared slurry, a spray dryer is used, which is a device that sprays (atomises) the liquid raw material into fine droplets and dries them with hot air to instantly obtain powder. Spray dryers are conventionally known devices, and examples include spray dryers manufactured by Okawara Chemical Engineering Co., Ltd., Fujisaki Electric Co., Ltd., and Japan Chemical Machinery Manufacturing Co., Ltd. In a spray dryer, the particle size of the powder particles (granules) obtained by drying can be controlled by changing the size of the droplets obtained by spraying (atomizing) the liquid raw material. The method for atomizing the liquid raw material using a spray dryer is not particularly limited, and any conventionally known method such as a two-fluid nozzle method, a pressure nozzle (pressurized nozzle) method, a four-fluid nozzle method (twin-jet nozzle method), or a rotating disk method can be appropriately selected depending on the desired droplet size. Since the particle size of the powder particles (granules) obtained by drying varies depending on the concentration of the slurry and / or the processing amount, in order to obtain the desired particle size, the state of the slurry must be appropriately selected in addition to the atomization method. The contact method between the hot air and the sprayed droplets can be appropriately selected from the following types: a general parallel flow type in which the hot air and sprayed droplets both flow downward; a counter flow type in which the hot air flows upward in a countercurrent to the downward flow of the sprayed droplets; and a parallel counter flow type in which the sprayed droplets flow upward and the hot air flows downward.

[0060] Spray drying applies heat instantaneously, so the powder itself does not easily become hot. Spray drying dries the slurry to directly obtain powder, eliminating the need for processes such as filtration, drying, and pulverization, and reducing contamination that can occur during these steps.

[0061] The above describes a method for obtaining a mold-containing powder by a spray drying process. However, as mentioned above, the method for obtaining the mold-containing powder is not particularly limited, and may be, for example, a method in which the slurry is subjected to fluidized bed drying (ball-type fluidized bed drying). In general, fluidized bed drying involves continuously feeding the material to be dried (slurry) onto a bed of 1-3 mm diameter ceramic balls in a fluidized bed, causing the material to adhere to the ball surfaces. The material is instantly dried by heat conduction from the heated balls and convection from the fluidized hot air, and is then peeled off from the ball surfaces by collisions between the balls. This yields a mold-containing powder.

[0062] By adjusting the procedure and conditions for obtaining the mold-containing powder, it is possible to adjust the particle size and shape of the granules in the obtained powder. Furthermore, by adjusting the procedure and conditions for obtaining the mold-containing powder, the amount and distribution of template particles in the granules contained in the mold-containing powder can be changed, and the structure of the coarse pores in the finally obtained aluminosilicate granules can be adjusted. Furthermore, adjusting the template particles used may contribute to the formation of the second pores described above.

[0063] <Mold removal process> The mold removal step is a step of removing mold particles from aluminosilicate granules contained in the mold-containing powder. When the mold particles are removed, coarse pores are formed in the aluminosilicate granules according to the shape and distribution of the mold particles. The treatment performed in the template removal step can be appropriately selected depending on the material of the template particles. Examples of treatments performed in the template removal step include a calcination treatment and an acid treatment. The calcination treatment and the acid treatment will be described below.

[0064] (Firing treatment) When resin particles, carbon particles, or the like are used as the template particles, the template particles can be removed by a baking treatment. The firing temperature, firing atmosphere and firing time in the firing treatment are not particularly limited as long as the template particles can be removed, and can be adjusted appropriately. The firing temperature is preferably 200° C. or higher, more preferably 300° C. or higher, and even more preferably 400° C. or higher. On the other hand, the firing temperature is preferably 1000° C. or lower, more preferably 900° C. or lower, and even more preferably 800° C. or lower. The firing time is preferably 0.5 hours or more, more preferably 0.75 hours or more, while the firing time is preferably 10 hours or less, more preferably 5 hours or less.

[0065] The firing atmosphere is not particularly limited, and may be, for example, air. When the template particles are resin particles or carbon particles, it is also preferable to use a firing atmosphere with a higher oxygen content than the air atmosphere.

[0066] The calcination treatment may cause the halloysite nanotube particles contained in the granules to change into metahalloysite nanotube particles.

[0067] (acid treatment) When magnesium oxide particles, calcium carbonate particles, zinc oxide particles, or the like are used as the template particles, the template particles can be removed by acid treatment. The acid treatment refers to a treatment in which the mold-containing powder is brought into contact with an acid treatment liquid, which is preferably a liquid containing water and an acidic component. The acidic treatment liquid may be any conventionally known aqueous acid solution, including inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as oxalic acid and acetic acid. The acidic treatment liquid may contain two or more acids. That is, the acidic treatment liquid may be a mixed acid. The acid concentration in the acidic treatment solution is not particularly limited as long as it can remove the template particles, but from the viewpoint of shortening the acid treatment time, it is preferably 0.1 mol / L or more, more preferably 1.0 mol / L or more, and even more preferably 2.0 mol / L or more. The upper limit of the acidic treatment solution is not particularly limited, but may be, for example, 12.0 mol / L or less. The type of acid contained in the acidic treatment solution can be appropriately selected depending on the desired physical properties, cost, and the like. In addition, it is preferable that the equipment for carrying out the acid treatment is made of a material that is corrosion-resistant to the acid contained in the acid treatment solution, for the parts that may come into contact with the acid treatment solution.

[0068] In the acid treatment, the mold-containing powder is brought into contact with the acid treatment solution, for example, by placing the mold-containing powder in the acid treatment solution and stirring the solution. The stirring method is not particularly limited, and for example, the acid treatment solution and the mold-containing powder may be placed in a tank equipped with a stirring blade and stirred. The ratio of the mass of the acid treatment liquid to the mass of the mold-containing powder can be set appropriately, but is, for example, 5 to 100, and 10 to 50 is preferred. The temperature of the acid treatment solution during the acid treatment can be set appropriately, for example, from 10 to 100°C, and preferably from 20 to 90°C. The acid treatment time can be adjusted appropriately depending on the type of template particles contained in the template-containing powder, the type of acid treatment liquid used, the ratio of the mass of the acid treatment liquid to the mass of the template-containing powder, and the temperature of the acid treatment liquid, but can be, for example, 10 minutes to 48 hours, with 30 minutes to 12 hours being preferred.

[0069] <Other processes> The method for producing halloysite powder of the present invention may further include other steps in addition to the steps described above.

[0070] For example, when an acid treatment is carried out as the template removal step, a pre-calcination step may be carried out before the acid treatment. Examples of the pre-calcination step include a treatment similar to the calcination treatment described above. The calcination temperature in the pre-calcination step is preferably 600 to 900°C. When calcination is carried out within the above-described preferred temperature range, the halloysite nanotube particles contained in the aluminosilicate granules become metahalloysite nanotube particles. When the acid treatment is performed after the pre-calcination step, the metahalloysite nanotube particles are also subjected to the acid treatment, and aluminosilicate granules containing acid-treated metahalloysite nanotube particles are obtained. As described above, the acid-treated metahalloysite nanotube particles often have third pores with a pore size of 8 nm or less, and the properties derived from the pores can be imparted to the resulting powder. Furthermore, the powder obtained by the pre-calcination step and acid treatment may be further subjected to a calcination treatment. The calcination temperature in the post-calcination step is preferably higher than 200°C and not higher than 1100°C, more preferably 300 to 1000°C. By performing the further calcination treatment, the physical properties of the powder can be controlled.

[0071] Furthermore, when a calcination treatment is performed as the template removal step, the above-mentioned acid treatment may be further performed after the calcination treatment. When the temperature in the calcination treatment as the template removal step is, for example, 600 to 900°C, the halloysite nanotube particles contained in the aluminosilicate granules become metahalloysite nanotube particles, and aluminosilicate granules containing acid-treated metahalloysite nanotube particles are obtained by the acid treatment. Furthermore, the powder obtained by the acid treatment may be subjected to the post-calcination step described above. The post-baking step and the acid treatment may be repeated.

[0072] The powder production method of the present invention may include a step of washing the obtained powder (washing step). The washing step is also preferably carried out between the acid treatment step and the post-calcination step described below. The washing step allows the acid treatment solution and the like to be removed from the obtained powder. The washing step is preferably a step of bringing the obtained powder into contact with a washing liquid. The washing liquid may be, for example, water. As the water, pure water (e.g., ion-exchanged water) may be used.

[0073] The method for contacting the obtained powder with the washing liquid may be the same as that for the acid treatment step. After contacting the powder with the washing liquid, the powder is separated from the washing liquid. The separation method is not particularly limited, and known methods can be applied, such as sedimentation separation and filtration separation. Sedimentation separation utilizes gravity or centrifugal force to separate the liquid and powder due to the difference in specific gravity. Filtration separation involves separating the powder from the liquid by trapping the powder in a filter or the like and passing the liquid through the filter. Filtration separation may be dead-end filtration or cross-flow filtration.

[0074] The washing step may be carried out repeatedly. For example, after the powder is separated from the washing liquid by the above method, the separated powder is again brought into contact with the washing liquid and the washing step is repeated. The washing step may be repeated, for example, until the conductivity of the filtrate reaches a predetermined level.

[0075] The powder obtained by the washing step may be subjected to a drying treatment. The drying method is not particularly limited, and known methods can be applied. The drying temperature is usually 200°C or lower.

[0076] <Specific examples of powder manufacturing methods> The method for producing the powder is as described above, and the steps described above may be carried out in the following order.

[0077] (Example 1) An example will be described in which resin particles that can be removed by baking treatment are added to the slurry containing halloysite nanotube particles in the above-mentioned slurry preparation step. When the slurry containing the resin particles is subjected to spray drying, which is a powder preparation step, aluminosilicate granules containing halloysite nanotube particles and resin particles are obtained. When aluminosilicate granules containing halloysite nanotube particles and resin particles are subjected to a baking treatment, which is a template removal step, the resin particles disappear and pores (coarse pores) corresponding to the shape of the resin particles are formed. The aluminosilicate granules that have been subjected to the above-mentioned calcination treatment have large pores, first pores derived from the nanotube particles, and second pores.

[0078] When the aluminosilicate granules are subjected to the above-mentioned firing treatment at a temperature of, for example, 600 to 900° C., the halloysite nanotube particles contained in the aluminosilicate granules are converted into metahalloysite nanotube particles. When the above-mentioned acid treatment is applied to aluminosilicate granules containing metahalloysite nanotube particles, aluminosilicate granules containing acid-treated metahalloysite nanotube particles are obtained. Additionally, as mentioned above, the aluminosilicate granules containing the acid-treated metahalloysite nanotube particles may be further subjected to a post-calcination step. The aluminosilicate granules containing acid-treated metahalloysite nanotube particles obtained by the above procedure have large pores, first pores derived from the nanotube particles, second pores, and third pores of 8 nm or less derived from the acid-treated metahalloysite nanotube particles.

[0079] (Example 2) An example will be described in which particles that can be removed by acid treatment (calcium carbonate particles) are added to the slurry containing halloysite nanotube particles in the above-mentioned slurry preparation step. When the slurry containing calcium carbonate particles is subjected to spray drying, which is a powder preparation step, aluminosilicate granules containing halloysite nanotube particles and calcium carbonate particles are obtained. When aluminosilicate granules containing halloysite nanotube particles and calcium carbonate particles are subjected to acid treatment, which is a template removal process, the calcium carbonate particles disappear and pores (coarse pores) corresponding to the shape of the calcium carbonate particles are formed. The aluminosilicate granules that have been subjected to the acid treatment have large pores, first pores derived from the nanotube particles, and second pores.

[0080] The aluminosilicate granules that have been subjected to the acid treatment may be further subjected to a calcination treatment. When the aluminosilicate granules are subjected to the above-mentioned firing treatment at a temperature of, for example, 600 to 900°C, the halloysite nanotube particles contained in the aluminosilicate granules are converted into metahalloysite nanotube particles. When the above-mentioned acid treatment is further applied to the aluminosilicate granules containing metahalloysite nanotube particles, aluminosilicate granules containing acid-treated metahalloysite nanotube particles are obtained. Additionally, as mentioned above, the aluminosilicate granules containing the acid-treated metahalloysite nanotube particles may be further subjected to a post-calcination step. The aluminosilicate granules containing acid-treated metahalloysite nanotube particles obtained by the above procedure have large pores, first pores derived from the nanotube particles, second pores, and third pores of 8 nm or less derived from the acid-treated metahalloysite nanotube particles.

[0081] (Example 3) Another example will be described in which particles that can be removed by acid treatment (calcium carbonate particles) are added to the slurry containing halloysite nanotube particles in the above-mentioned slurry preparation step. When the slurry containing calcium carbonate particles is subjected to spray drying, which is a powder preparation step, aluminosilicate granules containing halloysite nanotube particles and calcium carbonate particles are obtained. When aluminosilicate granules containing halloysite nanotube particles and calcium carbonate particles are subjected to a calcination treatment, the calcium carbonate particles are not removed, but the strength of the aluminosilicate granules is increased.

[0082] When the aluminosilicate granules that have been subjected to the above-mentioned calcination treatment are subjected to an acid treatment, which is a template removal step, the calcium carbonate particles disappear and pores (coarse pores) corresponding to the shape of the calcium carbonate particles are formed. The aluminosilicate granules that have been subjected to the acid treatment have large pores, first pores derived from the nanotube particles, and second pores.

[0083] When the aluminosilicate granules are subjected to the above-mentioned calcination treatment at a temperature of, for example, 600 to 900°C, the halloysite nanotube particles contained in the aluminosilicate granules are converted into metahalloysite nanotube particles at the same time as the calcium carbonate particles are removed. When the above-mentioned acid treatment is further applied to the aluminosilicate granules containing metahalloysite nanotube particles, aluminosilicate granules containing acid-treated metahalloysite nanotube particles are obtained. Additionally, as mentioned above, the aluminosilicate granules containing the acid-treated metahalloysite nanotube particles may be further subjected to a post-calcination step. The aluminosilicate granules containing acid-treated metahalloysite nanotube particles obtained by the above procedure have large pores, first pores derived from the nanotube particles, second pores, and third pores of 8 nm or less derived from the acid-treated metahalloysite nanotube particles.

[0084] (Example 4) An example will be described in which resin particles that can be removed by firing treatment and particles that can be removed by acid treatment (calcium carbonate particles) are added to the slurry containing halloysite nanotube particles in the above-mentioned slurry preparation step. When the slurry containing the resin particles and calcium carbonate particles is subjected to spray drying, which is a powder preparation step, aluminosilicate granules containing halloysite nanotube particles, resin particles, and calcium carbonate particles are obtained. When aluminosilicate granules containing halloysite nanotube particles, resin particles, and calcium carbonate particles are subjected to a baking treatment, which is a mold removal process, the resin particles disappear and pores (coarse pores) corresponding to the shape of the resin particles are formed.

[0085] Furthermore, when the aluminosilicate granules that have been subjected to the above-mentioned calcination treatment are subjected to an acid treatment, the calcium carbonate particles disappear and pores (coarse pores) corresponding to the shape of the calcium carbonate particles are formed. The aluminosilicate granules that have been subjected to the above-mentioned calcination treatment and acid treatment have large pores, first pores derived from the nanotube particles, and second pores.

[0086] In addition, when the aluminosilicate granules that have been subjected to the above-mentioned calcination treatment are calcined at a temperature of, for example, 600 to 900°C, the halloysite nanotube particles are converted into metahalloysite nanotube particles, and therefore, by acid treatment, aluminosilicate granules containing acid-treated metahalloysite nanotube particles are obtained. The aluminosilicate granules containing acid-treated metahalloysite nanotube particles obtained by the above procedure have large pores, first pores derived from the nanotube particles, second pores, and third pores of 8 nm or less derived from the acid-treated metahalloysite nanotube particles.

[0087] In the procedure of Example 4, the order of the acid treatment and the calcination treatment may be reversed. [Example]

[0088] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0089] [Example 1] Powder 1, which corresponds to the powder of the present invention, was produced by the following procedure.

[0090] <Raw material halloysite> As the raw material halloysite, halloysite manufactured by APPLIED MINERALS (product name: DRAGONITE-HP) was prepared.

[0091] <Slurrying> Raw halloysite, water, and anionic polymer surfactant (Poise 520, Kao Corporation) were placed in a high-speed mixer (Ultra Homo Mixer UHM-20 (20 liters), manufactured by Nippon Seiki Seisakusho Co., Ltd.) and processed at 10,000 rpm for 10 minutes to obtain a slurry (solids concentration: 40% by mass) in which the raw halloysite was dispersed in water. The content of the anionic polymer surfactant relative to the total solids of the slurry was 1.5% by mass.

[0092] <Centrifugation> The slurry was centrifuged for 10 minutes at a centrifugal force of 2500 G using a centrifuge (Kubota Shoji Co., Ltd., High-Speed, Large-Capacity Refrigerated Centrifuge 7000). The slurry was separated into a sedimentation phase and a dispersed phase, and the dispersed phase was recovered. The solids concentration of the dispersed phase (slurry) of nanotubes, from which impurities such as quartz and coarse particles had been removed, was 24% by mass. The solids concentration was measured using a halogen-heated moisture meter (Shinko Denshi Co., Ltd., MA-120) at a dry heat treatment temperature of 200°C.

[0093] <Addition of template particles> To 90 parts by mass of the solid content of the recovered dispersed phase (slurry), 10 parts by mass of template particles (polymethyl methacrylate particles, average particle size: 2.5 μm, MBX-2H manufactured by Sekisui Plastics Co., Ltd.) were added. Water was then added to adjust the total solid content to 25% by mass, and the template particles were dispersed in the slurry by processing for 10 minutes at 8000 rpm using a high-speed mixer (Ultra Homo Mixer UHM-20 manufactured by Nippon Seiki Seisakusho Co., Ltd.).

[0094] <Spray drying> The dispersed phase (slurry) to which the template particles were added was spray-dried using a spray dryer to obtain a template-containing powder. The spray dryer used was an L-8i spray dryer manufactured by Okawara Kakoki Co., Ltd. The slurry was supplied at a fixed rate using a pump to atomize (spray) the slurry. The contact method between the hot air and the spray droplets was a parallel flow type in which both the hot air and the spray droplets flowed downward. The spray drying conditions were as follows: Atomization method: Rotating disc method Disk rotation speed: 25000 RPM Water evaporation rate: 2.1 kg / h ·Inlet temperature: 190℃ ·Outlet temperature: 80℃

[0095] <Mold removal process> The resulting mold-containing powder was subjected to a firing treatment in an air atmosphere to remove the mold particles. Specifically, the temperature was raised at a rate of 4°C / min, the firing temperature was set to 650°C, and the firing time was set to 1 hour. The powder obtained by the above steps will be hereinafter referred to as "powder 1."

[0096] <Evaluation of Powder 1> Powder 1 was evaluated by the following methods.

[0097] (SEM observation) Powder 1 was observed by SEM. The observed images are shown in Figures 1 and 2. Figure 2 is an enlarged image of Powder 1. As shown in FIG. 1, SEM observation confirmed that the aluminosilicate granules contained in Powder 1 had pores (coarse pores) with a pore size of more than 200 nm. Furthermore, from the SEM image shown in Figure 2, it was confirmed that Powder 1 contained granules (aluminosilicate granules) formed by the aggregation of halloysite containing halloysite nanotube particles. It was also confirmed that pores (first pores) originating from the tube pores of the halloysite nanotube particles were present on the surface of the granules. Furthermore, it was confirmed that pores (second pores) larger in diameter than the tube pores of the halloysite nanotube particles were present on the cross section of the granules (not shown). From the above results, it was confirmed that Powder 1 has coarse pores and pores derived from tube pores, and is a powder with a novel structure.

[0098] (Nitrogen adsorption isotherm) In the present invention, nitrogen adsorption isotherms were obtained under the following conditions and procedures, and various analyses were carried out. First, the powder was pretreated (vacuum degassing at 120°C for 8 hours), and then the nitrogen adsorption and desorption isotherms were measured using a constant volume method under the following conditions: The equilibrium waiting time is the waiting time after the adsorption equilibrium state is reached. ·Adsorption temperature: 77K Nitrogen cross section: 0.162nm 2 Saturated vapor pressure: Actual measurement Equilibration time: 500 seconds Pretreatment device: BELPREP-vacII (Microtrack, manufactured by BEL) Measurement device: BELSORP-mini (Microtrack BEL) Analysis software: BELMaster Version 6.4.0.0 (Microtrack, BELMaster)

[0099] BET specific surface area [m 2 / g] was determined by applying the BET method to the nitrogen adsorption isotherm. The log differential pore volume distribution was calculated from the nitrogen adsorption isotherm by applying the BJH method using the FHH standard curve. The total pore volume was also calculated by the same method.

[0100] From the above measurements and analyses, the BET specific surface area and total pore volume of Powder 1 were as follows: ·BET specific surface area: 64.5m 2 / g Total pore volume: 0.44 cm 3 / g

[0101] The nitrogen adsorption isotherm of Powder 1 was analyzed for pore size distribution using the BJH method. The results are shown in Figure 3. In each graph, the horizontal axis represents pore size [nm], and the vertical axis represents differential pore volume (dVp / dlogDp) [cm 3 In the graph of FIG. 3, two or more pore diameter peaks were confirmed within the range of 10 nm or more (more than 8 nm and 200 nm or less).

[0102] (Average particle size) The average particle size of Powder 1 was measured by the method described above and was found to be 25.3 μm.

[0103] (Antibacterial test) A test (stirring method) was conducted to evaluate the antibacterial activity of Powder 1. Staphylococcus aureus (NBRC12732 strain) was used as the test bacterial strain. The specific antibacterial test procedure is as follows. First, 0.3 g of Powder 1 was weighed out and sterilized by dry heat at 160°C for 2 hours. The sterilized powder was added to 9.9 mL of sterile saline, and then 1.4 × 10 70.1 mL of a Staphylococcus aureus suspension containing CFU / mL was inoculated. The saline solution inoculated with the Staphylococcus aureus suspension was stored at 25°C while being rotary shaken at 200 rpm. After the specified storage time had elapsed, the solution was left to stand for 10 minutes to allow Powder 1 to settle, and 9.0 mL of the supernatant was sampled to measure the viable bacterial count. The antibacterial activity of Powder 1 was evaluated based on the change in viable bacterial count. A Staphylococcus aureus biological culture medium sheet (manufactured by JNC Corporation) was used to measure the viable bacterial count. The same test was also performed in a container containing another saline solution, for a total of three containers, and the antibacterial activity of Powder 1 was evaluated based on the average viable bacterial count. Data showing the transition of viable cell counts are shown in FIG. FIG. 4 also shows the change in viable cell count for a control run conducted under the same conditions except that Powder 1 was not added.

[0104] Furthermore, for comparison, Powder 2 was obtained using the same procedure as in obtaining Powder 1, except that the template particles were not added, and the same test was carried out (see Figure 4). SEM images of Powder 2 are shown in Figures 5 and 6. Figure 6 is an enlarged image of Powder 2. The observation image shown in Figure 5 confirmed that the aluminosilicate granules contained in Powder 2 did not have pores (coarse pores) with a pore size of more than 200 nm. In addition, the SEM image shown in Figure 6 confirmed that Powder 2 contained granules (aluminosilicate granules) formed by aggregation of halloysite containing halloysite nanotube particles. The BET specific surface area and total pore volume of Powder 2 were determined in the same manner as for Powder 1, and were found to be as follows: ·BET specific surface area: 63.5m 2 / g Total pore volume: 0.43 cm 3 / g

[0105] 4, it was confirmed that the number of viable bacteria decreased most rapidly over time and the antibacterial activity was highest when Powder 1 was added. Therefore, it was confirmed that the powder of the present invention (Powder 1) containing aluminosilicate granules with pores larger than 200 nm (coarse pores) exhibits superior antibacterial activity to the powder (Powder 2) containing aluminosilicate granules without coarse pores.

[0106] [Example 2] In the procedure for obtaining powder 1, first, a mold-containing powder was obtained in the same manner as the procedure for obtaining powder 1, except that the atomization method for the spray drying conditions was changed to a four-fluid nozzle and the spray air pressure was set to 0.20 MPa. The resulting mold-containing powder was subjected to a firing treatment in an air atmosphere to remove the mold particles. Specifically, the temperature was raised at a rate of 4°C / min, the firing temperature was set to 900°C, and the firing time was set to 1 hour. The powder obtained by the above steps will be referred to as "powder 3" hereinafter. Powder 3 obtained by the above procedure was treated with acid to obtain Powder 3A. The acid treatment was carried out by mixing hydrochloric acid with Powder 3A at a solid-liquid ratio (mass ratio) of 100:3.5 (hydrochloric acid:Powder 3) using 6 mol / L hydrochloric acid, and leaving the mixture to stand at room temperature for 18 hours. After the acid treatment, the mixture was washed with ion-exchanged water, separated into solid and liquid, and then dried at 110°C to obtain Powder 3A. When Powder 3 and Powder 3A were analyzed by XRF, the SiO2 / Al2O3 molar ratio was 2.0 in Powder 3, while the SiO2 / Al2O3 molar ratio in Powder 3A was 7.0. This suggests that Al2O3 was eluted by the acid treatment.

[0107] The BET specific surface area and total pore volume of Powder 3 were determined in the same manner as for Powder 1, and were found to be as follows: ·BET specific surface area: 60.8m 2 / g Total pore volume: 0.44 cm 3 / g The BET specific surface area and total pore volume of Powder 3A were determined in the same manner as for Powder 1, and were found to be as follows: ·BET specific surface area: 352.2m 2 / g Total pore volume: 0.76 cm 3 / g For Powder 3 and Powder 3A, nitrogen adsorption isotherms were measured in the same manner as for Powder 1, and the pore size distribution was analyzed by the BJH method. The results are shown in FIG. 7, two or more pore diameter peaks are observed within the range of 10 nm or more (more than 8 nm and less than 200 nm), and in Powder 3A, an additional pore diameter peak is observed around 2 nm, confirming that the acid treatment generates third pores with a pore diameter of 8 nm or less.

[0108] Powder 3 and Powder 3A were also observed by SEM. Observation images of Powder 3 are shown in Figures 8 and 9. Figure 9 is an enlarged image of Powder 3. Observation images of Powder 3A are shown in Figures 10 and 11. Figure 11 is an enlarged image of Powder 3A. 8 to 11, it was confirmed that the coarse pore structure seen in Powder 3 was also maintained in Powder 3A. That is, it was confirmed that Powder 3A is a powder with a novel structure having coarse pores, pores with a pore diameter of more than 8 nm and 200 nm or less, and third pores with a pore diameter of 8 nm or less.

[0109] [Example 3] In the procedure for obtaining the above-mentioned powder 3, calcium carbonate particles (average particle diameter 3.5 μm) were used as template particles, and 20 parts by mass of calcium carbonate particles were added to 80 parts by mass of the solid content of the slurry. Except for the above, spray drying was carried out in the same manner as in the procedure for obtaining powder 3, to obtain a template-containing powder. The resulting mold-containing powder was subjected to a firing treatment in an air atmosphere. Specifically, the temperature was raised at a rate of 4°C / min, and the mixture was fired at 650°C for 1 hour in an air atmosphere to obtain powder 4. Powder 4 (mold-containing powder) obtained by the above-mentioned firing treatment was subjected to an acid treatment to remove the mold particles (calcium carbonate particles), thereby obtaining Powder 4A. The acid treatment was carried out using 6 mol / L hydrochloric acid, mixing the template-containing powder with hydrochloric acid at a solid-liquid ratio (mass ratio) of 100:4 (hydrochloric acid:powder 4), and heating at 60°C for 2 hours. After the acid treatment, the mixture was washed with ion-exchanged water, separated into solid and liquid, and then dried at 110°C to obtain powder 4A. When Powder 4 and Powder 4A were analyzed by XRF, CaO was not detected in Powder 4A. Furthermore, the SiO2 / Al2O3 molar ratio of Powder 4 was 2.0, while the SiO2 / Al2O3 molar ratio of Powder 4A was 42.0. This suggests that CaO was removed from Powder 4 by the acid treatment, and some of the Al2O3 contained in Powder 4 was eluted. The BET specific surface area and total pore volume of Powder 4 were determined in the same manner as for Powder 1, and were found to be as follows: ·BET specific surface area: 56.5m 2 / g Total pore volume: 0.46 cm 3 / g The BET specific surface area and total pore volume of Powder 4A were determined in the same manner as for Powder 1, and were found to be as follows: ·BET specific surface area: 539.5m 2 / g Total pore volume: 0.67 cm 3 / g

[0110] Powder 4A was also observed by SEM. The observed images of Powder 4A are shown in Figures 12 and 13. Figure 13 is an enlarged image of Powder 4A. As shown in FIG. 12, it was confirmed that the aluminosilicate granules contained in Powder 4A had pores (coarse pores) with a pore size of more than 200 nm. 13, Powder 4A was confirmed to contain granules (aluminosilicate granules) formed by aggregations of halloysite containing halloysite nanotube particles. Analysis by the BJH method also confirmed that there were pores (first pores) derived from the tube pores of the halloysite nanotube particles, as well as pores (second pores) larger in diameter than the tube pores, and a pore diameter peak was present around 2 nm. From the above results, it was confirmed that Powder 4A is a powder with a novel structure having coarse pores, pores with a pore size of more than 8 nm and less than 100 nm, and third pores with a pore size of 8 nm or less.

Claims

1. Aluminosilicate granules comprising nanotube-like particles and having pores with a diameter of more than 200 nm.

2. The aluminosilicate granules according to claim 1, further having pores of more than 8 nm and not more than 200 nm.

3. The aluminosilicate granule according to claim 2, wherein the pores include first pores derived from the nanotube particles and second pores different from the first pores.

4. The aluminosilicate granules according to any one of claims 1 to 3, further having pores with a pore diameter of 8 nm or less.

5. The aluminosilicate granules according to any one of claims 1 to 3, comprising first pores derived from the nanotube particles and having a pore diameter of more than 8 nm and not more than 200 nm, second pores different from the first pores and having a pore diameter of more than 8 nm and not more than 200 nm, and third pores having a pore diameter of 8 nm or less.

6. The aluminosilicate granules according to any one of claims 1 to 3, wherein the nanotube particles are nanotube aluminosilicate particles.

7. The aluminosilicate granules according to any one of claims 1 to 3, wherein the nanotube particles comprise particles derived from halloysite nanotubes.

8. A powder comprising the aluminosilicate granules according to any one of claims 1 to 3.

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