Aluminum hydroxide powder and its manufacturing method

Abstract

To provide an aluminum hydroxide powder that can sufficiently suppress a viscosity rise when added to resin and a method for producing the same.SOLUTION: An aluminum hydroxide powder has a density of 1.59-2.00 g / cm3 when molded at 10 MPa, in which the ratio of diffraction intensity of (002) plane to diffraction intensity of (110) plane in an XRD pattern is 2.0-7.5.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to aluminum hydroxide powder and methods for making the same. [Background technology]

[0002] Demand for aluminum hydroxide powder is increasing as a filler for resin molded products (sealants, thermal interface materials (TIM), artificial marble, etc.). For example, in Patent Document 1, raw aluminum hydroxide is compressed in a compression chamber having a compression capacity of 5 to 500 kgf / cm 2 The present invention discloses a method for producing aluminum hydroxide for use as a filler, which is characterized by grinding the aluminum hydroxide in a screw-type kneader. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-322813 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been found that in the conventional technology disclosed in Patent Document 1, there is a risk that the viscosity of a resin may increase when aluminum hydroxide powder is added to the resin.

[0005] The present invention has been made in view of the above circumstances, and one of its objectives is to provide an aluminum hydroxide powder that can sufficiently suppress an increase in viscosity when added to a resin, and a method for producing the same. [Means for solving the problem]

[0006] Aspect 1 of the present invention is Density is 1.59-2.00g / cm when molded at 10MPa. 3 and The aluminum hydroxide powder has an XRD pattern in which the ratio of the diffraction intensity of the (002) plane to the diffraction intensity of the (110) plane is 2.0 to 7.5.

[0007] Aspect 2 of the present invention is The aluminum hydroxide powder according to aspect 1, having a 90% by mass particle size (D90) of less than 100 μm.

[0008] Aspect 3 of the present invention is The mass standard particle size distribution has one or two peaks in the particle size range of 1 to 200 μm, When there is one peak, the frequency of the peak is 4.0% by mass or more, In the aluminum hydroxide powder according to aspect 1 or 2, when there are two peaks, the frequency of one peak is 4.0 mass% or more, and the frequency of the other peak is more than 0 mass% and 4.0 mass% or less.

[0009] A fourth aspect of the present invention is The method for producing aluminum hydroxide powder comprises crushing aluminum hydroxide powder having a 50% mass particle size (D50) of 10 to 200 μm and a cumulative volume of pores with a radius of 0.05 to 1 μm of 0.01 to 1 mL / g under a pressure of 49.0 to 294.0 MPa, and then disintegrating the powder at a collision speed of 92 m / sec or less. Effect of the Invention

[0010] According to the embodiments of the present invention, it is possible to provide an aluminum hydroxide powder that can sufficiently suppress an increase in viscosity when added to a resin, and a method for producing the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present inventors have conducted research from various angles in order to realize an aluminum hydroxide powder that can sufficiently suppress an increase in viscosity (hereinafter also referred to as "resin viscosity") when added to a resin. As a result, they have found that an increase in resin viscosity can be sufficiently suppressed by controlling, within a predetermined range, the density when molded at 10 MPa (hereinafter also referred to as "molded density") and the ratio of the diffraction intensity of the (002) plane to the diffraction intensity of the (110) plane in the XRD pattern (hereinafter also referred to as "(002) / (110) diffraction intensity ratio"). In order to control the compaction density and the (002) / (110) diffraction intensity ratio within a predetermined range, the particle size and pore volume of the raw aluminum hydroxide powder are controlled within a predetermined range, and a higher pressure (500 to 3000 kgf / cm) than that of the conventional technology is used. 2 It was found that it is important to crush the powder at a pressure of 49.0 to 294.0 MPa and to disintegrate it at a relatively low impact speed of 92 m / s or less.

[0012] The following provides details of each requirement stipulated by the embodiment of the present invention.

[0013] <1. Aluminum hydroxide powder> The aluminum hydroxide powder according to the embodiment of the present invention has a density of 1.59 to 2.00 g / cm when molded at 10 MPa. 3 and the ratio of the diffraction intensity of the (002) plane to the diffraction intensity of the (110) plane in the XRD pattern is 2.0 to 7.5, thereby making it possible to sufficiently suppress an increase in the viscosity of the resin.

[0014] Molding density is 1.59g / cm 3 If the density is less than 1.0, the resin viscosity increases. There is no particular upper limit to the molding density, but it is preferably 2.00 g / cm3, for example. 3 More detailed manufacturing conditions are required to achieve a density of over 2.00 g / cm. 3 It is preferable to keep it as follows:

[0015] The molding density is determined as follows. 3.00 g of aluminum hydroxide powder is placed into a cylindrical uniaxial molding die with an inner diameter of 20.0 mm, and using a universal material testing machine (e.g., A&D's TENSILON RTG-1310), the aluminum hydroxide powder is compressed and packed at a compression speed of 1 mm / min until the pressure reaches 10 MPa, and the weight / volume ratio is the molding density.

[0016] If the (002) / (110) diffraction intensity ratio exceeds 7.5, the aluminum hydroxide powder, which may normally have a shape close to a sphere, will have a distorted shape, such as a plate shape, and the resin viscosity will increase. Preferably, the (002) / (110) diffraction intensity ratio is 6.0 or less. There is no particular lower limit to the (002) / (110) diffraction intensity ratio, but in order to make the (002) / (110) diffraction intensity ratio less than 2.0, more detailed production conditions must be set, and it is preferable to set the ratio to 2.0 or more in consideration of productivity.

[0017] The (002) / (110) diffraction intensity ratio is determined as follows. The aluminum hydroxide powder is compacted and packed into a glass cell for measurement, and then the XRD pattern is measured using a powder X-ray diffraction measuring device (e.g., Rigaku Corporation, RINT-2000) with a step width of 0.02 deg, a scan speed of 0.04 deg / sec, an acceleration voltage of 40 kV, and an acceleration current of 30 mA. Cu-Kα is used as the X-ray source. In the obtained XRD pattern, the peak appearing at 2θ=18.3° is taken as the peak of the (002) plane, and the peak appearing at 2θ=20.3° is taken as the peak of the (110) plane, and the ratio of the diffraction intensity (peak height) of the peak of the (002) plane to the diffraction intensity (peak height) of the peak of the (110) plane is taken as the (002) / (110) diffraction intensity ratio.

[0018] The aluminum hydroxide powder according to the embodiment of the present invention preferably has a 90% by mass particle size (i.e., the particle size at which the cumulative frequency from the fine particle side in the mass-based particle size distribution is 90% by mass, also referred to as D90) of less than 100 μm. This makes it possible to sufficiently suppress poor appearance when the aluminum hydroxide powder is filled into a resin molded body, and also makes it easier to ensure sufficient strength of the resin molded body. Preferably, D90 is 90 μm or less, more preferably 65 μm or less, and even more preferably 45 μm or less. The aluminum hydroxide powder according to the embodiment of the present invention preferably has a D90 of 20 μm or more, which can suppress poor dispersion when dispersing the aluminum hydroxide powder in a liquid.

[0019] The aluminum hydroxide powder according to the embodiment of the present invention preferably has one or two peaks in the particle size range of 1 to 200 μm in the mass particle size distribution. This can suppress poor appearance when the aluminum hydroxide powder is filled into a resin molded body, and can also suppress poor dispersion when the aluminum hydroxide powder is dispersed in a liquid. When there is one peak, the frequency of the peak may be 4.0 mass% or more. When there are two peaks, the frequency of one peak may be 4.0 mass% or more, and the frequency of the other peak may be more than 0 mass% and 4.0 mass% or less. In this case, it is preferable that there is only one peak in the particle size range of 1 to 200 μm in the mass particle size distribution. This can further suppress poor appearance and poor dispersion of the resin molded body.

[0020] The aluminum hydroxide powder according to the embodiment of the present invention may have, in a mass-based particle size distribution, one or more peaks in either or both of the particle size ranges of less than 1 μm and more than 200 μm, and the frequency of the peaks may be greater than 0 mass% and not more than 0.5 mass%, or may have no peaks in the particle size ranges of less than 1 μm and more than 200 μm.

[0021] The aluminum hydroxide powder according to the embodiment of the present invention preferably has a 50% by mass particle size (i.e., the particle size at which the cumulative frequency from the fine particle side in the mass-based particle size distribution is 50% by mass, also referred to as D50) of 30 μm or less. This makes it possible to suppress poor appearance when the aluminum hydroxide powder is filled into a resin molded body, and also makes it easier to ensure the strength of the resin molded body. The aluminum hydroxide powder according to the embodiment of the present invention preferably has a D50 of 7 μm or more, which can suppress poor dispersion when dispersing the aluminum hydroxide powder in a liquid.

[0022] The mass-based particle size distribution (including D50 and D90) is determined as follows. Aluminum hydroxide powder is added to a 0.2% by mass aqueous solution of sodium hexametaphosphate, and ultrasonic waves of 25 W are applied for 120 seconds to disperse the aluminum hydroxide powder in the aqueous solution. The mass-based particle size distribution (including D50 and D90) is determined using a laser scattering particle size distribution measuring device. The particle size distribution is determined by dividing the particle diameter range of 0.02 μm to 2000 μm into 132 parts on a logarithmic scale and measuring the mass of aluminum hydroxide having a particle diameter in each section. In addition, as the laser scattering particle size distribution measuring device, it is preferable to use a Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) or an equivalent device, taking into consideration the difference between devices and the consistency with the present embodiment. In addition, when measuring the particle size distribution, it is preferable to appropriately adjust the concentration of the aluminum hydroxide powder to a measurable concentration of the above measuring device before measuring.

[0023] The aluminum hydroxide powder according to the embodiment of the present invention has a BET specific surface area of ​​2.0 m 2 / g or less. This makes it possible to suppress poor dispersion when dispersing the aluminum hydroxide powder in a liquid. The BET specific surface area is determined by a nitrogen adsorption method using a fully automatic specific surface area measuring device (e.g., Macsorb HM-1201, manufactured by Mountech Co., Ltd.) in accordance with the method specified in JIS-Z-8830:2013.

[0024] The aluminum hydroxide powder according to the embodiment of the present invention contains Na as an impurity. 2 It may contain O. 2 The content of O is preferably, for example, 0.13 mass % or less. This makes it possible to suppress deterioration of the resin and a decrease in the insulating properties when the resin is filled into a resin molded body. 2 The O content is determined by dissolving aluminum hydroxide powder in an aqueous solution of an inorganic acid to prepare an aqueous solution, and then using an ICP emission spectrometer. 2 Converted to O, Na 2 The mass of NaO was calculated and the ratio of NaO to the mass of the dissolved aluminum hydroxide powder was 2 The ratio of the mass of O to Na 2 The aluminum hydroxide powder according to the embodiment of the present invention has an Al(OH) 3 and Na 2 In addition to O, it may contain inevitable impurities. As inevitable impurities, the inclusion of elements brought in due to the conditions of raw materials, materials, manufacturing equipment, etc. is permitted.

[0025] The aluminum hydroxide powder according to the embodiment of the present invention can sufficiently suppress the increase in viscosity when added to a resin, and is suitable as a filler for resin molded bodies (sealing material, thermal interface material (TIM), artificial marble, etc.). Applicable resins include thermosetting resins such as unsaturated polyester resin, epoxy resin, phenolic resin, and polyurethane resin, and thermoplastic resins such as polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and / or propylene with other α-olefins such as butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, 4-methylpentene-1, and decene-1, tyrenic (co)polymers, methyl methacrylate (co)polymers, polyamides, polycarbonates, ethylene-vinyl acetate copolymers, polyacetals, acrylonitrile-butadiene-styrene copolymers, polyphenylene oxides, polyethersulfones, polyarylates, polyetheretherketones, and polymethylpentenes. The aluminum hydroxide powder according to the embodiment of the present invention is not limited to the above-mentioned resins, and can also be used as a filler for other synthetic resins, natural resins, paper, and the like.

[0026] <2. Method for producing aluminum hydroxide powder> The method for producing an aluminum hydroxide powder according to an embodiment of the present invention includes the steps of (a) preparing an aluminum hydroxide powder having a 50% by mass particle size (D50) of 10 to 200 μm and a cumulative volume of pores with a radius of 0.05 to 1 μm of 0.01 to 1 mL / g, (b) pulverizing the powder at a pressure of 49.0 to 294.0 MPa, and (c) disintegrating the powder at a collision speed of 92 m / sec or less. Each step will be described in detail below.

[0027] [(a) Preparation of aluminum hydroxide powder] First, aluminum hydroxide powder (hereinafter also referred to as "raw aluminum hydroxide powder") is prepared as a raw material. The raw aluminum hydroxide powder must have a 50% mass particle size (D50) of 10 to 200 μm and a cumulative volume of pores with a radius of 0.05 to 1 μm (hereinafter also referred to as "cumulative pore volume") of 0.01 to 1 mL / g. This makes it easier to obtain a desired molding density. Preferably, the cumulative pore volume is 0.02 to 1 mL / g. This makes it easier to obtain a desired D90 and also makes it easier to obtain aluminum hydroxide powder with a desired mass-based particle size distribution.

[0028] If D50 is less than 10 μm or more than 200 μm, and / or the cumulative pore volume is less than 0.01 mL / g or more than 1 mL / g, it becomes difficult to obtain a desired molding density.

[0029] The cumulative pore volume is determined as follows. The aluminum hydroxide powder is dried at 120°C for 4 hours to remove adsorbed moisture. Then, 0.5 to 0.6 g is weighed out using a precision balance and filled into a measurement cell with a diameter of 15 mm and a height of 24 mm. This measurement cell is set in an automatic porosimeter (e.g., Autopore III9420, manufactured by Micromeritics), and measurements are performed separately on the low pressure side (1 to 10,000 psi) and the high pressure side (10,000 to 60,000 psi). These measurement data are added together to determine the pore volume distribution in the region of pore radius of 0.002 μm to 100 μm, and the cumulative volume in the region of pore radius of 0.05 μm to 1.0 μm is calculated.

[0030] The crystal structure of the raw material aluminum hydroxide powder may be, for example, a gibbsite type or a bayerite type, and is preferably a gibbsite type.

[0031] The raw aluminum hydroxide powder can be produced by adding seed crystals to a supersaturated sodium aluminate solution, hydrolyzing with stirring to precipitate aluminum hydroxide, and filtering, washing, and drying the aluminum hydroxide obtained. Here, the raw aluminum hydroxide powder having the above particle size and cumulative pore volume can be obtained by appropriately adjusting the precipitation conditions (and / or partially dissolving the precipitate, and / or crushing or crushing the precipitate), etc. Note that commercially available aluminum hydroxide powders may be used as long as they satisfy the above particle size and cumulative pore volume.

[0032] [(b) Grinding at a pressure of 49.0 to 294.0 MPa] Next, the raw aluminum hydroxide powder is pulverized at a pressure of 49.0 to 294.0 MPa. Here, "pulverization" refers to a process of applying some energy to solid particles (e.g., primary particles) of a certain size to make them smaller than their original size.

[0033] If the pressure during pulverization is less than 49.0 MPa, the desired molding density cannot be obtained. It is preferably more than 49.0 MPa, more preferably 68.6 MPa or more. There is no particular upper limit to the pressure during pulverization, but it is preferably 294.0 MPa or less in consideration of productivity.

[0034] Examples of the pulverizer that pulverizes under the above pressure include a co-kneader, an onlator, a self-cleaning type kneader, a gear compounder, a single-shaft screw type kneader, and a double-shaft screw type kneader. The above devices may be used alone or in combination of two or more. The pulverizer may be either a batch type or a continuous type, but a continuous type is preferred from the viewpoint of reducing the pulverization energy per unit weight. When using a continuous type pulverizer, it is not necessary that the raw aluminum hydroxide in the pulverizer is pulverized as a whole, and it is sufficient that the degree of pulverization is gradually increased in the transport direction (axial direction) of the raw aluminum hydroxide. In the case of a screw type kneader, the compression capacity can be adjusted by, for example, the shape, length, and rotation speed of the screw, the rotation speed of the rotor (which acts to transport the raw material to the screw), etc.

[0035] In the pulverizer, raw aluminum hydroxide powder is present as a solid phase, and in addition, air or the like is usually present as a gas phase, and water or the like is present as a liquid phase. Since the conditions in the pulverizer during pulverization can affect the physical properties of the aluminum hydroxide powder obtained by pulverization, it is preferable that the pulverization is performed in a state in which the solid, liquid, and gas phases are packed in (i) a dry state in which the solid and gas phases are continuous and the liquid phase is substantially absent, (ii) a pendular state in which the solid and gas phases are continuous and the liquid phase is discontinuous, or (iii) a funicular I state in which the solid, gas, and liquid phases are continuous. Such a packing form constitutes a mixture system that is smooth or dry in appearance.

[0036] It is preferable to adjust the liquid content of the raw aluminum hydroxide powder before pulverization so that a dry state, a pendular state, or a funicular I state is achieved during pulverization. The liquid content can be adjusted, for example, by drying the raw aluminum hydroxide powder or adding a liquid such as water or alcohol. The preferred liquid content varies depending on the particle size distribution of the raw aluminum hydroxide and is not unambiguous, but is, for example, 30% by weight or less, more preferably 10% by weight or less, and 1% by weight or more, more preferably 5% by weight or more. If the liquid content is too high, it becomes difficult to efficiently pulverize the raw aluminum hydroxide.

[0037] When a liquid such as water is added during pulverization, or when a raw aluminum hydroxide powder containing water is pulverized, the aluminum hydroxide powder after pulverization is usually dried. Drying can be performed, for example, by a method using a known dryer, or by a method of heating part of a continuous pulverizer when pulverization is performed using the continuous pulverizer.

[0038] [(c) crushing at a collision speed of 92 m / s or less] After the above step (b), the mixture is crushed at a collision speed of 92 m / s or less. Here, "crushing" refers to the operation of breaking down and finely dividing agglomerates of fine particles (e.g., secondary particles) into smaller particles (e.g., primary particles).

[0039] If the impact speed during crushing exceeds 92 m / sec, the desired (002) / (110) diffraction intensity ratio cannot be obtained. For example, by using an impact crusher, the above impact speed can be used for crushing.

[0040] The method for producing an aluminum hydroxide powder according to an embodiment of the present invention may include other steps (for example, a surface treatment step, etc.) within the scope in which the object of the present invention is achieved. EXAMPLES

[0041] The following examples are provided to more specifically describe the embodiments of the present invention. The embodiments of the present invention are not limited to the following examples, and may be modified as appropriate within the scope of the above and below-described aims, and all of these are included in the technical scope of the embodiments of the present invention.

[0042] The raw aluminum hydroxide powder (D50: 81 μm, pore cumulative volume: 0.09 mL / g) was adjusted to a moisture content of 5 wt% and continuously fed into a grinder (single-axis screw type kneader) for grinding. The grinder pressure was set to 196.0 MPa by adjusting the feeding speed. The grinder pressure was calculated by investigating the relationship between the pressing pressure and D90 by compressing and grinding the same raw aluminum hydroxide powder using a cold isostatic press separately, and the grinder pressure was calculated simply from the D90 of the ground aluminum hydroxide powder. The obtained pulverized product was dried at 120° C. and then charged into an impact pulverizer (Jiyuu pulverizer, manufactured by Nara Kikai) and pulverized to obtain the aluminum hydroxide powder of Example 1. The impact speed of the impact pulverizer was set to 46 m / sec. Moreover, aluminum hydroxide powders of Examples 2 to 4 and Comparative Examples 1 and 2 were obtained by changing the various conditions from the manufacturing method of Example 1 as shown in the following Table 1. Furthermore, commercially available aluminum hydroxide powders were designated as Comparative Example 3 (Sumitomo Chemical, CW-308), Comparative Example 4 (Sumitomo Chemical, C-305), and Comparative Example 5 (Sumitomo Chemical, CM-3080).

[0043] [Table 1]

[0044] The aluminum hydroxide powders of Examples 1 to 4 and Comparative Examples 1 to 5 were measured for compact density, (002) / (110) diffraction intensity ratio, mass-based particle size distribution (including D50 and D90), BET specific surface area, and Na 2 The O content was determined.

[0045] [Molding density] 3.00 g of aluminum hydroxide powder was placed into a cylindrical uniaxial molding die with an inner diameter of 20.0 mm, and using a universal material testing machine (A&D, TENSILON RTG-1310), the aluminum hydroxide powder was compressed and packed at a compression speed of 1 mm / min until the pressure reached 10 MPa, and the weight / volume ratio was taken as the molding density.

[0046] [(002) / (110) diffraction intensity ratio] The aluminum hydroxide powder was compacted and packed into a glass cell for measurement, and then the XRD pattern was measured using a powder X-ray diffraction measuring device (Rigaku Corporation, RINT-2000) with a step width of 0.02 deg, a scan speed of 0.04 deg / sec, an acceleration voltage of 40 kV, and an acceleration current of 30 mA. Cu-Kα was used as the X-ray source. In the obtained XRD pattern, the peak appearing at 2θ=18.3° was taken as the peak of the (002) plane, and the peak appearing at 2θ=20.3° was taken as the peak of the (110) plane, and the ratio of the diffraction intensity (peak height) of the peak of the (002) plane to the diffraction intensity (peak height) of the peak of the (110) plane was taken as the (002) / (110) diffraction intensity ratio.

[0047] [Mass-based particle size distribution (including D50 and D90)] Aluminum hydroxide powder was added to a 0.2% by mass aqueous solution of sodium hexametaphosphate, and ultrasonic waves of 25 W were applied for 120 seconds to disperse the aluminum hydroxide powder in the aqueous solution. The mass-based particle size distribution (including D50 and D90) was determined using a laser scattering particle size distribution measuring device. The particle size distribution was determined by dividing the particle size range of 0.02 μm to 2000 μm into 132 parts on a logarithmic scale and measuring the mass of aluminum hydroxide having a particle size in each section. As the laser scattering particle size distribution measuring device, Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) was used. In addition, when measuring the particle size distribution, the concentration of the aluminum hydroxide powder was appropriately adjusted to a measurable concentration of the measuring device, and then the measurement was performed.

[0048] [BET specific surface area] The BET specific surface area was determined by the nitrogen adsorption method using a fully automatic specific surface area measuring device (Mountech, Macsorb HM-1201) in accordance with the method specified in JIS-Z-8830:2013.

[0049] [Na 2 O content] Aluminum hydroxide powder was dissolved in an aqueous solution of an inorganic acid to prepare an aqueous solution, and then Na was measured using an ICP emission spectrometer. 2 The O content was calculated. Specifically, the intensity of the sodium wavelength (589.592 nm) was measured, and the Na 2 Converted to O, Na 2 The mass of NaO was calculated and the ratio of NaO to the mass of the dissolved aluminum hydroxide powder was 2 The ratio of the mass of O to Na 2 The O content (mass%) was used.

[0050] Furthermore, the resin viscosity was determined by the following method. 5.59 parts by mass of aluminum hydroxide powder and 1.86 parts by mass of bisphenol A type epoxy resin mixture (AQ010-8140, room temperature curing resin 53 type base agent) were mixed at 1000 rpm for 3 minutes using a planetary mixer (Thinky Corporation, Awatori Rentaro ARV-310) to obtain a compound. A 30 mm diameter parallel plate was attached to a dynamic viscoelasticity measuring device (Rheosol-G3000), and the above compound was set on it. After leaving it for 10 minutes under the conditions of a gap of 0.50 mm between the parallel plates and a temperature of 100 °C, the mixture was subjected to a shear rate of 40 s -1 The resin viscosity was measured at 100°C. The results are summarized in the following Table 2. In Table 2, "-" in the "second peak" column means that a second peak was not present.

[0051] [Table 2]

[0052] From the results in Table 2, the following can be considered. All of Examples 1 to 4 in Table 2 are examples that satisfy all of the requirements stipulated in the embodiments of the present invention, and the resin viscosity was 10 Pa s or less, and the increase in resin viscosity could be sufficiently suppressed. Among them, Examples 1 to 3 were preferable examples in that they had a D90 of less than 100 μm, and therefore were able to sufficiently suppress poor appearance when filled into a resin molded body, and also made it easy to ensure sufficient strength of the resin molded body. In Example 4, the cumulative pore volume of the raw aluminum hydroxide powder was less than 0.02 mL / g, and therefore D90 was 100 μm or more. On the other hand, Comparative Examples 1 to 5 are examples that do not satisfy the requirements defined in the embodiment of the present invention, and the resin viscosity exceeded 10 Pa·s, so that the increase in the resin viscosity could not be sufficiently suppressed.

[0053] In Comparative Example 1, the collision speed during crushing exceeded 92 m / sec, so that the (002) / (110) diffraction intensity ratio exceeded 7.5 and the resin viscosity exceeded 10 Pa·s.

[0054] In Comparative Example 2, the pressure during crushing was less than 49.0 MPa, so the molding density was 1.59 g / cm 3 and the resin viscosity exceeded 10 Pa s.

[0055] Comparative Examples 3 and 4 have a molding density of 1.59 g / cm 3 Because the viscosity was less than 10 Pa s, the resin viscosity exceeded 10 Pa s.

[0056] In Comparative Example 5, the (002) / (110) diffraction intensity ratio was more than 7.5, and therefore the resin viscosity was more than 10 Pa·s.

Claims

1. Density when molded at 10 MPa is 1.59 to 2.00 g / cm ３ and the ratio of the diffraction intensity of the (002) plane to the diffraction intensity of the (110) plane in the XRD pattern is 2.0 to 7.5; The 50% by mass particle size (D50) is 33 μm or less, The BET specific surface area is 2.0 m 2 / g or less; The mass standard particle size distribution has one or two peaks in the particle size range of 1 to 200 μm, The aluminum hydroxide powder has no peak or one or more peaks having a frequency of more than 0 mass% and not more than 0.5 mass% below 1 μm in the mass-based particle size distribution.

2. The aluminum hydroxide powder according to claim 1, having a 90% by mass particle size (D90) of less than 100 μm.

3. When the mass-based particle size distribution has one peak in a particle size range of 1 to 200 μm, the frequency of the peak is 4.0 mass% or more, 3. The aluminum hydroxide powder according to claim 1, wherein, when the mass-based particle size distribution has two peaks in the particle size range of 1 to 200 μm, the frequency of one peak is 4.0 mass% or more, and the frequency of the other peak is more than 0 mass% and 4.0 mass% or less.

4. A method for producing an aluminum hydroxide powder, comprising crushing an aluminum hydroxide powder having a 50% mass particle size (D50) of 10 to 200 μm and a cumulative volume of pores with a radius of 0.05 to 1 μm of 0.01 to 1 mL / g at a pressure of 49.0 to 294.0 MPa, and then disintegrating the aluminum hydroxide at a collision speed of 92 m / sec or less.

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