Flaky boehmite granulated product and production method thereof

Abstract

To provide: a flaky boehmite granulated product which is easy to mix with a base material such as a resin due to low volume and is broken in the base material such as a resin filled therewith so that flaky boehmite can easily disperse as a primary particle; and a production method thereof.SOLUTION: A flaky boehmite granulated product according to the present invention obtained by granulating flaky boehmite with an inorganic particle which is a binder. The granulated product, as heated at a temperature increase rate of 30°C / min in thermogravimetric analysis with a weight decrease ratio to 100°C of 0 wt.%, has the weight decrease ratio of from 100°C to 400°C of 1.1 wt.% or less. A production method of a flaky boehmite granulated product includes the steps of: granulating a suspension containing flaky boehmite and an inorganic particle which is a binder with stirring to obtain a flaky boehmite granulated product; and drying the flaky boehmite granulated product.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a scaly boehmite granule that is granulated with inorganic particles serving as a binder, and which has low bulk and can be stably supplied to a base material such as a resin, and which disintegrates in the base material such as a resin and is easily dispersed as primary particles of scaly boehmite, and a method for producing the same. [Background technology]

[0002] Boehmite, which is alumina monohydrate (AlOOH), is highly versatile and is used as a filler for reinforcing materials, flame retardants, luminescent materials, fireproofing materials, thickeners, etc., and is also used as a catalyst carrier, an electrically conductive filler base material, refractories, raw materials for high-purity alumina, raw materials for sinterable alumina, raw materials for fluorescent materials, etc. Boehmite can be produced by controlling its shape, so boehmite crystals have various shapes such as cubes, needles, hexagonal plates, disks, flat plates, flakes, and scales, and the hexagonal plates, disks, flat plates, flakes, and scales are sometimes collectively called plate-like. However, primary particles of boehmite with a large aspect ratio (particle major axis / particle thickness), such as flakes and scales, are bulky and therefore have poor fluidity and tend to fly around. Therefore, there are problems in that it is difficult to mix with base materials such as solvents and resins, and is also difficult to handle. More specifically, there are issues that the powder tends to float on the liquid surface when added to a solvent, and takes time to become mixed with the solvent, and that the supply speed to a kneader with a resin (e.g., an extrusion molding machine) is slow, making it difficult to increase productivity and the filling amount.

[0003] Conventionally, there have been proposals for techniques to reduce the bulk of powdery, granular, or lumpy substances. For example, a water suspension containing aluminum hydroxide and any one of additives selected from sodium hydroxide, a mixture of sodium hydroxide and sodium carbonate, and a mixture of sodium hydroxide and sodium phosphate is subjected to hydrothermal treatment while stirring to reduce the tap density of 0.22 g / cm. 3It is disclosed that the above-mentioned low bulk scaly boehmite aggregates can be obtained (Patent Document 1).Furthermore, as a technique for increasing the bulk density of a filler and improving the supply stability and supply accuracy of the filler when preparing a resin composition, a low bulk filler granule containing a filler, a binder, and a dispersant, the bulk density of the filler is 0.01 kg / L to 1 kg / L, the binder contains a water-soluble polymer, and the content ratio of the filler is 80 parts by weight to 99.9 parts by weight relative to 100 parts by weight of the total amount of the filler, the binder, and the dispersant is disclosed (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-106713 A [Patent Document 2] JP 2023-032657 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the scaly boehmite aggregates disclosed in the above Patent Document 1 have strong crystal cohesion, and cannot be dispersed and oriented as primary particles of scaly boehmite that have been de-agglomerated in a matrix such as a filled resin, and therefore have a problem in that the characteristics of the anisotropic shape of the scaly boehmite cannot be utilized.In addition, the filler granules disclosed in the above Patent Document 2 have low weather resistance because an organic binder is used, and there is a problem in that gas is generated during mixing with the resin, and the resin may blow out from the vent hole of the extruder.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a scaly boehmite granule which has a low bulk and is therefore easily mixed with a base material such as a resin, and in which the granules break apart in the base material such as a filled resin, allowing the scaly boehmite to be easily dispersed as primary particles, and a method for producing the same. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors of the present invention have conducted intensive research and arrived at the present invention. That is, the invention described in claim 1 relates to a scaly boehmite granule in which scaly boehmite is granulated with inorganic particles serving as a binder, and the scaly boehmite granule is characterized in that, in a thermogravimetric analysis, the weight loss rate at 100°C is set to 0 wt%, and when heated at a heating rate of 30°C / min, the weight loss rate from 100°C to 400°C is 1.1 wt% or less.

[0008] The invention described in claim 2 is the invention described in claim 1, wherein the tap density is 0.20 g / cm 3 The invention as recited in claim 3, in the invention as recited in claim 1, may be such that the size of the primary particles of the scaly boehmite is 1 μm to 20 μm. The invention as recited in claim 4, in the invention as recited in claim 1, may be such that the aspect ratio of the primary particles of the scaly boehmite is 10 to 100. The invention as recited in claim 5, in the invention as recited in claim 1, may be such that the ratio of the inorganic particles as a binder to the scaly boehmite is 0.5 wt % to 5.0 wt %. In the invention described in claim 6, in the invention described in claim 1, the primary particle size of the inorganic particles serving as the binder may be 10 nm to 200 nm.

[0009] The invention described in claim 7 is the invention described in any one of claims 1 to 6, wherein the inorganic particles serving as a binder may be one or more of alumina hydrate and amorphous silica. An eighth aspect of the present invention is the seventh aspect of the present invention, wherein the inorganic particles serving as a binder may be any one or more selected from the group consisting of aluminum hydroxide, pseudoboehmite, and silica nanoparticles.

[0010] The invention described in claim 9 relates to a method for producing scaly boehmite granules according to any one of claims 1 to 6, comprising a step of obtaining scaly boehmite granules by stirring and granulating a suspension containing scaly boehmite and inorganic particles as a binder, and a step of drying the scaly boehmite granules.The invention described in claim 10 relates to the invention described in claim 9, wherein granulation is performed by spraying a suspension containing inorganic particles.

[0011] The invention described in claim 11 is a method for producing a granulated scaly boehmite D 10 , D 50 , D 99 and D when scale-like boehmite granules are dispersed in water. 10 , D 50 , D 99 The present invention relates to a method for producing a scaly boehmite granule according to claim 9, characterized in that a rate of change in particle size calculated by the following formula (1) when comparing the same particle size distributions in the above is within 12%: (|AB| / B)×100 (1) A: Particle size of scaly boehmite granules after dispersion in water, B: Particle size of scaly boehmite before granulation

[0012] The invention described in claim 12 relates to use of the scaly boehmite granules described in any one of claims 1 to 6, characterized in that the granules are used as a filler for thermoplastic resins or thermosetting resins. Effect of the Invention

[0013] The scaly boehmite granules of the present invention have a high tap density and low bulk, and therefore are easily kneaded with a base material such as a resin and have excellent filling properties. In addition, since the scaly boehmite is granulated using inorganic particles as a binder, the amount of outgassing is small during heat-applied processes such as resin processing, and the production efficiency of resin products is high.

[0014] The scaly boehmite granules of the present invention are easily broken down when kneaded with a base material such as resin, and can be dispersed and oriented in the base material as primary particles of scaly boehmite, so that the variation in properties of the final product caused by poor dispersion can be suppressed. For example, in the case of filler use, it is possible to reduce the variation in properties of filled materials such as resin, and in the case of paint use, it is possible to reduce the variation in properties in the coating liquid. Furthermore, properties derived from the scaly shape, such as reinforcing properties and gas barrier properties, can be imparted to base materials such as resin.

[0015] The method for producing scaly boehmite granules of the present invention granulates scaly boehmite without using an organic binder, so that no organic binder remains in the scaly boehmite granules. A problem with typical organic binders is that they do not have high weather resistance and deteriorate, and there is a possibility that the granules cannot be maintained for a long period of time using organic binders. However, the present invention makes it possible to produce granules made of scaly boehmite that have high weather resistance. [Brief description of the drawings]

[0016] [Figure 1] 1 is a scanning electron microscope image (hereinafter referred to as "SEM image") of Example 1. [Diagram 2] This is a partially enlarged SEM image of the SEM image in Figure 1. [Diagram 3] 1 is an SEM image of a fracture surface of a resin composition into which the scaly boehmite granules of Example 1 are kneaded. [Figure 4] 1 is an SEM image of a fracture surface of a resin composition kneaded with scaly boehmite aggregates of Comparative Example 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In the thermogravimetric analysis, the scaly boehmite granules of the present invention preferably have a weight loss rate of 1.1 wt% or less, more preferably 1.0 wt% or less, from 100°C to 400°C when heated at a heating rate of 30°C / min, with the weight loss rate at 100°C being 0 wt%. If the weight loss rate exceeds 1.1 wt%, outgassing occurs when the scaly boehmite granules are kneaded with a resin, and the resin swells during molding, which reduces productivity and adversely affects the quality of the resin product. In the present invention and this specification, the term "scaly" refers not only to a scaly shape but also to all shapes that are sometimes collectively called plate-like, such as hexagonal plate-like, disk-like, flat, flake-like, and scaly shapes.

[0018] The scaly boehmite granules of the present invention have a tap density of 0.20 g / cm 3 More than 0.25 g / cm is preferable. 3 More preferably, the tap density is 0.20 g / cm or more. 3 If the tap density is equal to or greater than this, the bulk is lower than that of the primary particles of scaly boehmite in which the raw material scaly boehmite crystals are dispersed, and the primary particles of scaly boehmite are difficult to mix with a base material such as a solvent or resin, and the handling properties are poor. The higher the tap density of the scaly boehmite granules of the present invention, the lower the bulk, so no upper limit is set. However, if necessary, it is possible to set the tap density to 1.0 g / cm. 3 That's fine too.

[0019] The primary particle size of the raw material scaly boehmite is preferably a highly crystalline micro-size having an average length of the longest diagonal flat surface (average particle size) of 1 μm to 20 μm as measured by a scanning electron microscope. If the average particle size of the scaly boehmite is less than 1 μm, the crystals of the scaly boehmite granules are strongly bonded to each other, and the scaly boehmite granules are difficult to break apart when kneaded with a resin. If the primary particle size of the scaly boehmite exceeds 20 μm, the surface smoothness of the resin molding is reduced when used as a filler, and the weight per boehmite particle increases, which may reduce the effect per unit weight.

[0020] The aspect ratio, which is the ratio of the length (major axis) of the longest diagonal flat surface of the raw material scaly boehmite to the particle thickness, is preferably 10 to 100. If the aspect ratio is less than 10, a large amount must be added to fully obtain the effect of enhancing reinforcing properties when used as a filler, while if the aspect ratio exceeds 100, the particle thickness becomes relatively thin and is easily broken, and may not be able to exhibit sufficient reinforcing performance when used as a filler.

[0021] The ratio of the inorganic particles as a binder to the scaly boehmite is preferably 0.5wt% to 5.0wt%, and more preferably 1.0wt% to 5.0wt%. If it is less than 0.5wt%, scaly boehmite granules are not generated, and if it exceeds 5.0wt%, the inorganic particles are prone to moisture absorption due to the large specific surface area, and the amount of gas generated during molding of resin products etc. increases, leading to molding defects and deterioration of properties.

[0022] The primary particle size of the inorganic particles as the binder is preferably 10 nm to 200 nm, more preferably 10 nm to 150 nm. If the size is less than 10 nm, the inorganic particles tend to aggregate with each other, making handling difficult, and if the size exceeds 200 nm, the granulation force is weak, making it difficult to obtain scaly boehmite granules.

[0023] The types of inorganic particles that serve as binders include aluminum hydroxide gel, alumina hydrates such as pseudoboehmite, transition alumina in crystalline phases such as gamma phase, delta phase, theta phase, and chi phase, amorphous silica such as precipitated silica, silica sol, colloidal silica, and silica nanoparticles, calcium compounds such as calcium hydroxide, calcium oxide, and calcium carbonate, magnesium compounds such as magnesium hydroxide, magnesium oxide, and magnesium carbonate, titanium compounds such as titanium hydroxide and titanium oxide, and zirconium oxide. Among these, aluminum hydroxide gel, alumina hydrates such as pseudoboehmite, and amorphous silica such as silica nanoparticles are particularly preferred. Two or more of these may be used as the binder.

[0024] Next, the method for producing the scaly boehmite granules of the present invention will be described. The scaly boehmite granules of the present invention can be obtained by spraying a suspension containing inorganic particles onto scaly boehmite, mixing while fluidizing the mixture, and drying the mixture.

[0025] The concentration of the suspension containing inorganic particles is preferably 0.5 wt% to 5.0 wt%, and more preferably 1.0 wt% to 5.0 wt%. If the concentration is less than 0.5 wt%, the amount of suspension sprayed during production of scaly boehmite granules increases, and a predetermined amount of powder does not flow uniformly, and if the concentration exceeds 5.0 wt%, the inorganic particles in the suspension tend to clog the spray nozzle.

[0026] Examples of methods for producing scaly boehmite granules include stirring granulation, fluidized bed granulation, rolling granulation, vibration granulation, and crushing of dried cake. From the viewpoints of reducing the bulk of the granulated particles and ease of production, stirring granulation is preferred.

[0027] There are many different types of agitation mixers that can be used for agitation granulation, such as single-shaft, twin-shaft, and planetary types, and the shapes and sizes of the agitation blades are also diverse. Therefore, it is necessary to set the number of agitations, mixing speed, and mixing time for each agitation mixer to be used by trial and error. The number of stirring steps, mixing speed and mixing time are not particularly limited as long as the desired granules can be obtained. Mixing may be performed continuously or intermittently. If the mixing time of the stirring mixer used is too short or the mixing speed is too slow, granulation does not proceed well. If the mixing time is too long or the mixing speed is too fast, the granules may collapse or the shape of the scaly crystals of the scaly boehmite may be destroyed. Although the stirring speed, mixing speed and mixing time of the stirring mixer used for stirring granulation cannot be universally set, for example, the mixing speed may be 0.3 m / s or more, 0.5 m / s or more, and 5 m / s or less, 4 m / s or less. In addition, the mixing time may be 0.5 minutes or more, 1 minute or more, and 60 minutes or less, 45 minutes or less. For example, in the case of a planetary type soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.), the revolution speed of the stirrer may be 50 to 200 rpm.

[0028] The drying temperature of the granules after stirring and mixing may be any temperature at which the solvent of the suspension evaporates. For example, if an aqueous suspension is sprayed, the temperature may be 100°C or higher. The upper limit of the drying temperature is 400°C or lower, so long as the scaly boehmite does not change to alumina.

[0029] The scaly boehmite granules of the present invention are D of the scaly boehmite before granulation. 10 , D 50 , D 99 and D when scale-like boehmite granules are dispersed in water. 10 , D 50 , D 99 It is preferable that the rate of change in particle size calculated by the following formula (1) when comparing the same particle size distributions in is within 12%. (|AB| / B)×100 (1) A: Particle size of scaly boehmite granules after dispersion in water, B: Particle size of scaly boehmite before granulation If the rate of change exceeds 12%, this indicates that the scaly boehmite is strongly granulated and therefore difficult to disperse, and that when the scaly boehmite granules are filled into a base material such as a resin, the granules break apart in the base material, making it difficult to disperse as primary particles of scaly boehmite.

[0030] The resin to be blended with the scaly boehmite granules of the present invention is not particularly limited, and examples thereof include general-purpose resins such as epoxy resins, silicone resins, melamine resins, urea resins, phenol resins, unsaturated polyesters, fluororesins, polyamides such as polyimides, polyamideimides, and polyetherimides, polyesters such as polybutylene terephthalate and polyethylene terephthalate, polyphenylene sulfide, wholly aromatic polyesters, liquid crystal polymers, polysulfones, polyethersulfones, polycarbonates, maleimide-modified resins, ABS resins, acrylonitrile-acrylic rubber-styrene resins, acrylonitrile-ethylene-propylene-diene rubber-styrene resins, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, acrylic resins, nylon, modified polyphenylene ethers, and cyclic polyolefins. EXAMPLES

[0031] Next, the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

[0032] Example 1 100 g of scaly boehmite (average primary particle size: 5 μm, aspect ratio: 20 (both average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.) and stirred at 70 rpm to form an aqueous suspension (solids concentration: 1.7 wt%, D of solids) in which aluminum hydroxide gel (Tomita AD200P, manufactured by Tomita Pharmaceutical Co., Ltd.) was dispersed. 50 The mixture was dried at 120° C. to obtain boehmite granules containing 2.0 wt % of aluminum hydroxide gel.

[0033] Example 2 100 g of scaly boehmite (average primary particle size: 5 μm, aspect ratio: 20 (both average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.) and stirred at 70 rpm to form an aqueous suspension (solids concentration: 2.5 wt%, D of solids) in which aluminum hydroxide gel (Tomita AD200P, manufactured by Tomita Pharmaceutical Co., Ltd.) was dispersed. 50 120 g of 120 nm (120 g) was sprayed onto the mixture and mixed for another 1 minute. The mixture was dried at 120° C. to obtain boehmite granules containing 3.0 wt % of aluminum hydroxide gel.

[0034] Example 3 100 g of scaly boehmite (average primary particle size: 9 μm, aspect ratio: 30 (both average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.) and stirred at 70 rpm to form an aqueous suspension (solids concentration: 1.7 wt%, D of solids) in which aluminum hydroxide gel (Tomita AD200P, manufactured by Tomita Pharmaceutical Co., Ltd.) was dispersed. 50 The mixture was dried at 120° C. to obtain boehmite granules containing 2.0 wt % of aluminum hydroxide gel.

[0035] Example 4 100 g of scaly boehmite (average primary particle size: 2 μm, aspect ratio: 40 (both average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.) and stirred at 70 rpm to form an aqueous suspension (solid concentration: 1.7 wt%, D of solids) in which aluminum hydroxide gel (Tomita AD200P, manufactured by Tomita Pharmaceutical Co., Ltd.) was dispersed. 50 The mixture was dried at 120° C. to obtain boehmite granules containing 2.0 wt % of aluminum hydroxide gel.

[0036] Example 5 100 g of scaly boehmite (average primary particle size: 5 μm, aspect ratio: 20 (both average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.) and mixed at 70 rpm with silica nanoparticles (Snowtex C, manufactured by Nissan Chemical Co., Ltd., D 50 120 g of an aqueous suspension of 1.7 wt% of silica nanoparticles (12 nm) was sprayed onto the mixture and mixed for another 1 minute. The mixture was dried at 120°C to obtain boehmite granules containing 2.0 wt% of silica nanoparticles.

[0037] Comparative Example 1 100 g of scaly boehmite (average primary particle size: 5 μm, aspect ratio: 20 (both values ​​are average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Sekiryo Kogyo Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.), and while stirring and mixing at 70 rpm, 120 g of a solution of polyvinyl alcohol (10% polyvinyl alcohol solution, manufactured by Hayashi Pure Chemical Industries Co., Ltd.) diluted to 1.7 wt% with water was sprayed onto the mixture, which was then mixed for another 1 minute. The resulting mixture was dried at 120°C to obtain boehmite granules containing 2.0 wt% polyvinyl alcohol.

[0038] Comparative Example 2 100g of scaly boehmite (average primary particle size: 5μm, aspect ratio: 20 (both values ​​are average values ​​measured at 20 points on SEM images), manufactured by Kawai Sekiryo Kogyo Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.), and while stirring and mixing at 70 rpm, 120g of a solution of polyacrylic acid (25% polyacrylic acid solution (8000-12000cps), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) diluted with water to 1.7wt% was sprayed onto the mixture, which was then mixed for another 1 minute. The resulting mixture was dried at 120°C to obtain boehmite granules containing 2.0wt% polyacrylic acid.

[0039] Comparative Example 3 100g of scaly boehmite (average primary particle size: 5μm, aspect ratio: 20 (both values ​​were averaged from 20 measurements taken from SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.), and while stirring and mixing at 70 rpm, 80g of an aqueous suspension containing 3.8wt% liquid paraffin (Hicol K-350, manufactured by Kaneda Co., Ltd.) was sprayed onto the mixture, which was then mixed for another 1 minute. The resulting mixture was dried at 120°C to obtain boehmite granules containing 3.0wt% liquid paraffin.

[0040] Comparative Example 4 100 g of scaly boehmite (average primary particle size: 5 μm, aspect ratio: 20 (both average values ​​obtained by measuring 20 points on SEM images), manufactured by Kawai Lime Industry Co., Ltd.) was placed in a soil mixer (model number KS-54, manufactured by Kansai Machinery Manufacturing Co., Ltd.) and stirred at 70 rpm to form an aqueous suspension (solids concentration: 4.2 wt%, D of solids) in which aluminum hydroxide gel (Tomita AD200P, manufactured by Tomita Pharmaceutical Co., Ltd.) was dispersed. 50 120 g of 120 nm (120 g) was sprayed onto the mixture and mixed for another 1 minute. The mixture was dried at 120° C. to obtain boehmite granules containing 6.0 wt % of aluminum hydroxide gel.

[0041] Comparative Example 5 260 g of sodium carbonate (Tokuyama Corp.) was added to 3000 g of soft water and stirred until a transparent aqueous solution was obtained. 300 g of aluminum hydroxide (grade name: BF083, average particle size (laser diffraction / scattering method): 10 μm, average value of primary particles (measured length of 30 points from SEM image): 6.5 μm, Nippon Light Metals Co., Ltd.) was added thereto and stirred thoroughly to prepare an aqueous suspension. This aqueous suspension was placed in a stirring autoclave (volume: 5 L) and hydrothermally treated at 180°C for 6 hours while stirring at 1.49 m / sec (blade diameter: 0.142 m, rotation speed: 200 rpm). The temperature was raised from room temperature (25°C) to 180°C in 2 hours. The slurry after hydrothermal treatment was dehydrated, washed with water, and dried to obtain scaly boehmite aggregates.

[0042] The following various tests were carried out on the above-mentioned Examples and Comparative Examples.

[0043] 1. Granulation When the sample was visually inspected after drying, if granules were found, it was rated as ◯, and if no granules were found, it was rated as ×. 2. Weight loss rate from 100℃ to 400℃ The measurements were performed using a simultaneous differential thermal and thermogravimetric analyzer (TG-DTA 2000SA, manufactured by Bruker AXS Co., Ltd.) The heating rate was 30°C / min, and the weight loss rate up to 400°C was read based on 100°C. 3. Tap density 5 g or 10 g of the sample was placed in a 100 mL graduated cylinder and dropped from a certain height at a certain speed until the volume stopped changing. The volume after filling was read and the tap density was calculated using the following formula (2). Tap density (g / cm 3 ) = sample weight (g) / volume after filling (cm 3 )(2) 4. Dispersibility evaluation 0.3 g of the sample was placed in 30 mL of 0.2% sodium hexametaphosphate aqueous solution and subjected to ultrasonic treatment for 15 seconds using an ultrasonic homogenizer. After ultrasonic treatment, the particle size distribution (volume basis) of the sample was measured using a laser diffraction / scattering type particle size distribution measuring device (MT3000, manufactured by Microtrack Bell Co., Ltd.). The D of the obtained scaly boehmite before granulation was 10 , D 50 , D 99 and D when scale-like boehmite granules are dispersed in water. 10 , D 50 , D 99 When the rate of change in particle size calculated by the following formula (1) comparing the same particle size distributions in was within 12%, the dispersibility was evaluated as good and ◯, and when it was not, it was evaluated as ×. (|AB| / B)×100 (1) A: Particle size of scaly boehmite granules after dispersion in water, B: Particle size of scaly boehmite before granulation 5. Observation of the fracture surface of the resin composition in which the sample was kneaded For Example 1 and Comparative Example 5, the samples were kneaded into the resins listed below to prepare resin compositions, and the fracture surfaces of the resin compositions were observed by SEM images. (1) Resin type: Epoxy resin (bisphenol A type) (Product name: R140P, Manufacturer: Mitsui Chemicals, Inc.) (2) Preparation method: 20 g of epoxy resin was placed in a 205 mL paper cup, and 16.3 g of the sample was gradually added. This process of mixing was repeated using a planetary centrifugal mixer (ARE-310, manufactured by Thinky Corporation). After the sample was mixed and mixed, 0.4 g of 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) was added, thoroughly mixed and degassed, and then heated and cured at 120°C for 2 hours. The resulting cured product was processed into the desired shape to obtain a test piece of the resin composition. The test piece was frozen with liquid nitrogen and cut to obtain a fracture surface. This fracture surface was observed using an SEM image.

[0044] Table 1 shows the properties of the boehmite and the type of binder of the examples and comparative examples, Table 2 shows the granulation conditions, and Table 3 shows the analysis results.

[0045] [Table 1]

[0046] [Table 2]

[0047] [Table 3]

[0048] (1) In Examples 1 to 5, scaly boehmite granules were obtained by granulating scaly boehmite with inorganic particles as a binder. From FIG. 1, it can be seen that in Example 1, scaly boehmite was granulated with inorganic particles as a binder. Also, from FIG. 2, it can be seen that fine inorganic particles (which look like "haze") were adsorbed on the surface and end faces of the crystals of scaly boehmite, and the plate faces were bonded together or end faces were bonded to each other. Since the SEM images of other Examples were similar to FIG. 1 and FIG. 2, the drawings were omitted. The weight loss rate of the scaly boehmite granules of Examples 1 to 5 at 100°C to 400°C was 1.1 wt% or less in all cases. Also, the tap density of the scaly boehmite granules of Examples 1 to 5 was higher than the tap density of the primary particles of the scaly boehmite as the raw material (see Table 1), and it can be seen that the bulky primary particles of the scaly boehmite were granulated to reduce the bulk. The scaly boehmite granules of Examples 1 to 5 have good dispersibility in water, so when filled into a base material such as a resin, the granules break down in the base material and the scaly boehmite can be easily dispersed as primary particles. (2) Comparative Examples 1 and 2, in which scaly boehmite was granulated with an organic binder, had a higher weight loss rate at 100°C to 400°C than the Examples, and it can be said that there is a higher risk of outgassing when the granules are kneaded with resin and of the resin swelling during molding than in the Examples. In addition, the dispersibility of the granules in Comparative Examples 1 and 2 in water is not good (especially D 99 When filled into a base material such as a resin, the granules break down in the base material and are difficult to disperse into primary particles of scaly boehmite. (3) In Comparative Example 3, in which liquid paraffin was used as the binder, the scaly boehmite could not be granulated. (4) In Comparative Example 4, the ratio of binder to scaly boehmite is higher than in the Examples, so even though granulation is possible, the dispersibility in water is not good (especially D 99 When filled into a base material such as a resin, the granules break down in the base material and are difficult to disperse into primary particles of scaly boehmite. (5) Comparative Example 5 of the scaly boehmite aggregate was synthesized by hydrothermal treatment using aluminum hydroxide as a raw material, and since scaly boehmite was not used as a raw material, the particle size of the scaly boehmite before granulation could not be measured. Therefore, the dispersibility in water could not be evaluated, but it can be said that the scaly boehmite aggregate is difficult to disperse in water because the aggregates are strongly aggregated between the scaly boehmite crystals. (6) In the SEM image of FIG. 3, no boehmite granules are observed as in the SEM image of FIG. 1. It is found that the scaly boehmite granules of Example 1 are dissolved in the resin composition, and the primary particles of the scaly boehmite are oriented and dispersed in the resin. On the other hand, in the SEM image of FIG. 4, numerous boehmite aggregates are observed, and it is understood that the scaly boehmite aggregates of Comparative Example 5 are not broken down in the resin composition and are present as aggregates in the resin composition. From the above, it can be seen that the scaly boehmite granules of the present invention can be dispersed and oriented as primary particles of scaly boehmite in a matrix such as a resin, and the characteristics of the anisotropic shape of the scaly boehmite can be utilized. [Industrial Applicability]

[0049] The boehmite granules of the present invention have a large tap density and good dispersibility, and are therefore suitable as a filler for resins and the like, or as a raw material for catalyst carriers.

Claims

1. The scaly boehmite granules are produced by granulating scaly boehmite with inorganic particles as a binder, and are characterized in that, in a thermogravimetric analysis, the weight loss rate at 100°C is 0 wt% and when heated at a temperature increase rate of 30°C / min, the weight loss rate from 100°C to 400°C is 1.1 wt% or less.

2. Tap density is 0.20 g / cm ３ 2. The scaly boehmite granule according to claim 1,

3. 2. The scaly boehmite granule according to claim 1, characterized in that the primary particle size of the scaly boehmite is 1 μm to 20 μm.

4. 2. The scaly boehmite granule according to claim 1, characterized in that the aspect ratio of the primary particles of the scaly boehmite is 10 to 100.

5. 2. The scaly boehmite granule according to claim 1, characterized in that the ratio of the inorganic particles as the binder to the scaly boehmite is 0.5 wt % to 5.0 wt %.

6. 2. The scaly boehmite granule according to claim 1, characterized in that the primary particle size of the inorganic particles serving as the binder is 10 nm to 200 nm.

7. The scaly boehmite granule according to any one of claims 1 to 6, characterized in that the inorganic particles serving as a binder are at least one of alumina hydrate and amorphous silica.

8. 8. The scaly boehmite granule according to claim 7, wherein the inorganic particles serving as a binder are at least one selected from the group consisting of aluminum hydroxide, pseudoboehmite, and silica nanoparticles.

9. The method for producing the scaly boehmite granules according to any one of claims 1 to 6, characterized in that it comprises: a step of obtaining scaly boehmite granules by stirring and granulating a suspension containing the scaly boehmite and inorganic particles as a binder; and a step of drying the scaly boehmite granules.

10. 10. The method for producing scaly boehmite granules according to claim 9, wherein in the granulation step, granulation is performed by spraying a suspension containing inorganic particles.

11. D of scaly boehmite before granulation １０ , D ５０ , D ９９ and D when scaly boehmite granules are dispersed in water. １０ , D ５０ , D ９９ The method for producing scaly boehmite granules according to claim 9, characterized in that the rate of change in particle size calculated by the following formula (1) when comparing the same particle size distributions in the above is within 12%: (|A-B| / B)×100 (1) A: Particle size of scaly boehmite granules after dispersion in water, B: Particle size of scaly boehmite before granulation

12. 7. Use of the scaly boehmite granules according to any one of claims 1 to 6, characterized in that the granules are used as a filler for thermoplastic resins or thermosetting resins.

Images