Aluminum hydroxide powder

Abstract

To provide an aluminum hydroxide powder that can sufficiently suppress a viscosity rise when added to resin.SOLUTION: An aluminum hydroxide powder has a first molding density of 1.60-2.20 g / cm3, which is a molding density when molded at 10 MPa, in which the ratio of a second molding density, which is a molding density when molded at 0.5 MPa, to the first molding density is 0.875-0.970.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to aluminum hydroxide powder.

Background Art

[0002] The demand for aluminum hydroxide powder as a filler for resin molded articles (sealing materials, thermal interface materials (TIM), artificial marble, etc.) is increasing. For example, Patent Document 1 discloses a method for producing aluminum hydroxide for filler use, characterized by pulverizing raw material aluminum hydroxide with a screw-type kneader having a compression capacity of 5 to 500 kgf / cm 2 There is disclosed a method for producing aluminum hydroxide for filler use, characterized by pulverizing raw material aluminum hydroxide with a screw-type kneader having a compression capacity of 5 to 500 kgf / cm

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art as disclosed in Patent Document 1, it has been found that there is a risk of easy thickening when aluminum hydroxide powder is added to a resin.

[0005] The present invention has been made in view of such a situation, and one of its objects is to provide aluminum hydroxide powder that can sufficiently suppress an increase in viscosity when added to a resin.

Means for Solving the Problems

[0006] Aspect 1 of the present invention is a first molding density, which is the molding density when molded at 10 MPa, is 1.60 to 2.20 g / cm 3 and The aluminum hydroxide powder is such that the ratio of the second molding density, which is the molding density when molded at 0.5 MPa, to the first molding density is 0.875 to 0.970.

[0007] Aspect 2 of the present invention is the aluminum hydroxide powder according to Aspect 1, which contains silicon or titanium.

[0008] Aspect 3 of the present invention is the content of the silicon is 0.02 to 0.30% by mass in terms of SiO 2 converted value, and the content of the titanium is 0.01 to 0.30% by mass in terms of TiO 2 converted value, which is the aluminum hydroxide powder according to Aspect 2.

[0009] Aspect 4 of the present invention is the aluminum hydroxide powder according to any one of Aspects 1 to 3, wherein the particle size (D90) of 90% by mass is less than 100 μm.

[0010] Aspect 5 of the present invention is having one or two peaks in the particle size range of 1 to 200 μm in the mass-based particle size distribution, when there is one peak, the frequency of the peak is 4.0% by mass or more, when there are two peaks, the frequency of one peak is 4.0% by mass or more, and the frequency of the other peak is more than 0% by mass and 4.0% by mass or less, which is the aluminum hydroxide powder according to any one of Aspects 1 to 4.

Advantages of the Invention

[0011] According to the embodiment 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.

Modes for Carrying Out the Invention

[0012] The inventors of the present invention have studied from various angles in order to realize aluminum hydroxide powder that can sufficiently suppress an increase in viscosity (hereinafter also referred to as "resin viscosity") when added to a resin and can sufficiently suppress appearance defects when filled in a resin molded body. As a result, it has been found that by controlling the ratio of the density when molded at 10 MPa (hereinafter also referred to as "first molding density") and the density when molded at 0.5 MPa (hereinafter also referred to as "second molding density") with respect to the first molding density within a predetermined range, an increase in resin viscosity can be sufficiently suppressed. Furthermore, it has been found that a desired first molding density and a ratio of the second molding density / first molding density can be obtained by a production method including pulverization at a pressure greater than that of the prior art (500 to 3000 kgf / cm 2 , that is, 49.0 to 294.0 MPa).

[0013] Details of each requirement defined by the embodiments of the present invention are shown below.

[0014] <1. Aluminum hydroxide powder> The aluminum hydroxide powder according to the embodiment of the present invention has a first molding density, which is the molding density when molded at 10 MPa, of 1.60 to 2.20 g / cm 3 and the ratio of the second molding density, which is the molding density when molded at 0.5 MPa, to the first molding density is 0.875 to 0.970. Thereby, an increase in resin viscosity can be sufficiently suppressed.

[0015] When the first molding density is less than 1.60 g / cm 3 , the resin viscosity increases. The first molding density is preferably 1.63 g / cm 3 or more, and more preferably 1.66 g / cm 3 or more. There is no particular limitation on the upper limit of the first molding density. For example, in order to exceed 2.20 g / cm 3 , more detailed production conditions need to be set, and considering productivity, it is preferable to keep it at 2.20 g / cm 3 or less.

[0016] When the ratio of the second molding density to the first molding density is less than 0.875, the resin viscosity increases. The upper limit of the ratio of the second molding density to the first molding density is not particularly limited. However, in order to make the ratio of the second molding density to the first molding density exceed 0.970, more detailed setting of manufacturing conditions is required. Considering productivity, it is preferably set to 0.970 or less.

[0017] The first molding density shall be determined as follows. Put 3.00 g of aluminum hydroxide powder into a mold for uniaxial molding of a cylinder with an inner diameter of 20.0 mm, and use a universal material testing machine (for example, TENSILON RTG-1310 manufactured by A&D Company). Compress and fill the aluminum hydroxide powder at a compression rate of 1 mm / min until the pressure reaches 10 MPa, and use the weight / volume ratio as the first molding density. The second molding density shall be determined in the same manner as above, except that the pressure is changed from 10 MPa to 0.5 MPa.

[0018] The aluminum hydroxide powder according to the embodiment of the present invention preferably has a particle size of less than 100 μm for 90% by mass (that is, 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). Thereby, when the aluminum hydroxide powder is filled into the resin molded body, appearance defects can be sufficiently suppressed, and the strength of the resin molded body can be easily ensured sufficiently. Preferably, D90 is 90 μm or less, more preferably 65 μm or less, and still more preferably 45 μm or less. The aluminum hydroxide powder according to the embodiment of the present invention preferably has D90 of 20 μm or more. Thereby, poor dispersion when dispersing the aluminum hydroxide powder in a liquid can be suppressed.

[0019] As an example in which the aluminum hydroxide powder according to the embodiment of the present invention satisfies a desired first molding density and the ratio of the second molding density to the first molding density, it may contain silicon or titanium. In the above case, the content of silicon is SiO 2It is preferably 0.02% by mass or more in terms of conversion value, and the titanium content is TiO 2 It is preferably 0.01% by mass or more in terms of conversion value. This makes it easier to adjust to the desired first molding density and the ratio of the second molding density to the first molding density. On the other hand, although the upper limits of the silicon and titanium contents are not particularly limited, considering productivity, it is preferably 0.30% by mass or less for each.

[0020] The aluminum hydroxide powder according to the embodiment of the present invention may contain sodium as an impurity. The sodium content is preferably 0.13% by mass or less, for example, in terms of Na 2 O conversion value. This can suppress the deterioration of the resin and the decrease in insulation when filled in the resin molded body.

[0021] The contents of silicon, titanium, and sodium are determined using an ICP emission spectroscopic analyzer after preparing an aqueous solution by dissolving the aluminum hydroxide powder in an aqueous solution of an inorganic acid. Specifically, the intensities of the wavelengths of silicon (251.611 nm), titanium (334.940 nm), and sodium (589.592 nm) are measured, and they are converted into SiO 2 , TiO 2 and Na 2 O, and the masses of SiO 2 , TiO 2 and Na 2 O are calculated. The ratios of the masses of SiO 2 , TiO 2 and Na 2 O to the mass of the dissolved aluminum hydroxide powder are taken as the contents (mass%) of silicon, titanium, and sodium, respectively. Further, the aluminum hydroxide powder according to the embodiment of the present invention may contain unavoidable impurities in addition to Al(OH) 3 , SiO 2 , TiO 2 and Na 2 O. As unavoidable impurities, the inclusion of elements and the like brought in due to the situation of raw materials, materials, manufacturing equipment, etc. is allowed.

[0022] The aluminum hydroxide powder according to an embodiment of the present invention preferably has one or two peaks in the particle size range of 1 to 200 μm in the mass-based particle size distribution. Thereby, it is possible to suppress appearance defects when the aluminum hydroxide powder is filled in a resin molded body, and it is also possible to further suppress dispersion defects when the aluminum hydroxide powder is dispersed in a liquid. When there is one peak, the frequency of the peak can be 4.0 mass% or more. When there are two peaks, the frequency of one peak can be 4.0 mass% or more, and the frequency of the other peak can be more than 0 mass% and 4.0 mass% or less. In this case, preferably, there is only one peak in the particle size range of 1 to 200 μm in the mass-based particle size distribution. Thereby, appearance defects and dispersion defects of the resin molded body can be further suppressed.

[0023] The aluminum hydroxide powder according to an embodiment of the present invention may have one or more peaks in each of one or both of the particle size ranges less than 1 μm and more than 200 μm in the mass-based particle size distribution, and the frequency of the peak may be more than 0 mass% and 0.5 mass% or less, or may not have a peak in the particle size ranges less than 1 μm and more than 200 μm.

[0024] The aluminum hydroxide powder according to an embodiment of the present invention preferably has a 50 mass% particle size (that is, the particle size at which the cumulative frequency from the fine particle side in the mass-based particle size distribution becomes 50 mass%, also referred to as D50) of 30 μm or less. Thereby, it is possible to suppress appearance defects when the aluminum hydroxide powder is filled in a resin molded body, and it is also easy to ensure the strength of the resin molded body. The aluminum hydroxide powder according to an embodiment of the present invention preferably has a D50 of 7 μm or more. Thereby, it is possible to suppress dispersion defects when the aluminum hydroxide powder is dispersed in a liquid.

[0025] Note that the mass-based particle size distribution (including D50 and D90) is determined as follows. Aluminum hydroxide powder is added to isopropyl alcohol, and ultrasonic waves with an output of 25 W are irradiated for 120 seconds to disperse the aluminum hydroxide powder in an aqueous solution. Then, 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 measuring the mass of aluminum hydroxide having a particle size in each of 132 divisions in the range of 0.02 μm to 2000 μm on a logarithmic scale. As the laser scattering particle size distribution measuring device, considering the difference between devices and the consistency with this example, it is preferable to use Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) or an equivalent device. Also, at the time of measuring the particle size distribution, it is advisable to measure after appropriately adjusting the concentration of the aluminum hydroxide powder to a measurable concentration of the above measuring device.

[0026] The aluminum hydroxide powder according to the embodiment of the present invention preferably has a BET specific surface area of 2.0 m 2 / g or less. Thereby, it is possible to suppress poor dispersion when dispersing the aluminum hydroxide powder in a liquid. The BET specific surface area is determined by the nitrogen adsorption method using a fully automatic specific surface area measuring device (for example, Macsorb HM-1201 manufactured by Mountech Co., Ltd.) in accordance with the method specified in JIS-Z-8830:2013.

[0027] The aluminum hydroxide powder according to an embodiment of the present invention can sufficiently suppress an increase in viscosity when added to a resin, and is suitable as a filler for a resin molded body (sealing material, thermal interface material (TIM), artificial marble, etc.). Examples of applicable resins include thermosetting resins such as unsaturated polyester resins, epoxy resins, phenolic resins, and polyurethane resins, and polyolefins represented by polyethylene, polypropylene, copolymers of ethylene and propylene, and copolymers of ethylene and / or propylene and other α-olefins such as butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, 4-methylpentene-1, and decene-1, styrene (co)polymers, methyl methacrylate (co)polymers, polyamides, polycarbonates, ethylene-vinyl acetate copolymers, polyacetals, acrylonitrile-butadiene-styrene copolymers, polyphenylene oxides, polyethersulfones, polyarylates, polyetheretherketones, polymethylpentenes, and other thermoplastic resins. The aluminum hydroxide powder according to an embodiment of the present invention is not limited to the above resins, and can also be used as a filler for other synthetic resins, natural resins, or paper.

[0028] In an example of a method for producing the aluminum hydroxide powder according to an embodiment of the present invention, a step of preparing an aluminum hydroxide powder having a particle size (D50) of 50% by mass of 10 to 200 μm and a cumulative volume of pores having a radius of 0.05 to 1 μm of 0.01 to 1 mL / g, a step of pulverizing at a pressure of 49.0 to 294.0 MPa, and a step of disintegrating at a collision speed of 92 m / s or less are included. Hereinafter, each step will be described in detail.

[0029] [Step of preparing aluminum hydroxide powder] Prepare aluminum hydroxide powder as a raw material (hereinafter also referred to as "raw material aluminum hydroxide powder"). The raw material aluminum hydroxide powder has a particle size (D50) of 10 to 200 μm at 50% by mass, and the cumulative volume of pores with a radius of 0.05 to 1 μm (hereinafter also referred to as "pore cumulative volume") can be 0.01 to 1 mL / g. These make it easier to obtain the desired first molding density and the ratio of the second molding density to the first molding density. Preferably, the pore cumulative volume is 0.02 to 1 mL / g. This makes it easier to obtain the desired D90 and also makes it easier to obtain aluminum hydroxide powder with a desired particle size distribution based on mass.

[0030] The pore cumulative volume is determined as follows. Dry the aluminum hydroxide powder at 120°C for 4 hours to remove adsorbed moisture. Then, weigh about 0.5 to 0.6 g with a precision balance and fill it into a measuring cell with a diameter of 15 mm and a height of 24 mm. Set this measuring cell in an automatic porosimeter (for example, AutoPore III 9420 manufactured by Micromeritics) and measure it separately on the low-pressure side (1 to 10,000 psi) and the high-pressure side (10,000 to 60,000 psi). Combine these measurement data, obtain the pore volume distribution in the region where the pore radius is 0.002 μm or more and 100 μm or less, and calculate the cumulative volume in the region where the pore radius is 0.05 μm or more and 1.0 μm or less.

[0031] The crystal structure of the raw material aluminum hydroxide powder is, for example, gibbsite type, boehmite type, etc., and preferably gibbsite type.

[0032] The raw material aluminum hydroxide powder can be produced by adding seed crystals to a sodium aluminate solution in a supersaturated state, hydrolyzing while stirring to precipitate aluminum hydroxide, filtering, washing, and drying the obtained aluminum hydroxide. Here, by appropriately adjusting the precipitation conditions (and / or partially dissolving the precipitated product, and / or pulverizing or crushing the precipitated product), etc., a raw material aluminum hydroxide powder having the above particle size and cumulative pore volume can be obtained. Note that as long as it satisfies the above particle size and cumulative pore volume, a commercially available aluminum hydroxide powder may be used.

[0033] [Step of pulverizing at a pressure of 49.0 to 294.0 MPa] The above raw material aluminum hydroxide powder is pulverized at a pressure of 49.0 to 294.0 MPa. Here, "pulverizing" means an operation of applying some energy to solid particles of a certain size (for example, primary particles) to make them smaller than the original size.

[0034] By pulverizing at a pressure of 49.0 MPa or more, it becomes easier to obtain a desired first molding density and the ratio of the second molding density to the first molding density. More preferably, it is more than 49.0 MPa, and still more preferably 68.6 MPa or more. The upper limit of the pressure during pulverization is not particularly limited, but considering productivity, it is preferably set at 294.0 MPa or less.

[0035] Examples of the crusher for crushing at the above pressure include a kneader, an on-roller, a self-cleaning kneader, a gear compounder, a single-screw kneader, a twin-screw kneader, etc. The said device may be used alone or in combination of two or more. Also, the crusher can be applied to either batch or continuous type, but the continuous type is preferred from the viewpoint of reducing the crushing energy per unit weight. When using a continuous crusher, it is not always necessary that the raw material aluminum hydroxide in the crusher is entirely crushed. For example, the degree of crushing may be increased sequentially in the transfer direction (axial direction) of the raw material aluminum hydroxide. In the case of a screw kneader, the compression capacity can be adjusted by, for example, the shape, length and rotation speed of the screw, and the rotation speed of the rotor (which functions to transfer the raw material to the screw).

[0036] In the crusher, there exists raw material aluminum hydroxide powder as a solid phase, and in addition, usually, air etc. as a gas phase and water etc. as a liquid phase exist. Since the states of those in the crusher during crushing may affect the physical properties of the aluminum hydroxide powder obtained by crushing, the crushing is preferably carried out in a filling form of the solid phase, liquid phase and gas phase in which (a) a dry state where the solid phase and the gas phase are continuous and the liquid phase is substantially absent, (b) a pendular state where the solid phase and the gas phase are continuous and the liquid phase is discontinuous, or (c) a funicular I state where the solid phase, the gas phase and the liquid phase are continuous. Such a filling form constitutes a powdery or lumpy mixed system in appearance.

[0037] It is preferable to perform pulverization after adjusting the liquid content rate of the raw material aluminum hydroxide powder before pulverization so that a dry state, a pendular state, or a funicular I state is achieved during pulverization. The adjustment of the liquid content rate can be performed, for example, by drying the raw material aluminum hydroxide powder or adding a liquid such as water or alcohol. The preferable liquid content rate varies depending on the particle size distribution of the raw material aluminum hydroxide and is not uniquely defined. For example, it is 30% by weight or less, more preferably 10% by weight or less, and also 1% by weight or more, more preferably 5% by weight or more. If the liquid content rate becomes too high, it becomes difficult to efficiently pulverize the raw material aluminum hydroxide.

[0038] When a liquid such as water is added during pulverization or when pulverizing a raw material aluminum hydroxide powder containing water or the like, the pulverized aluminum hydroxide powder is usually dried. Drying can be performed, for example, by using a known dryer or, when pulverization is performed using a continuous pulverizer, by heating a part of this pulverizer.

[0039] [Step of disintegrating at a collision speed of 92 m / s or less] After the above step, disintegrate at a collision speed of 92 m / s or less. Here, "disintegrate" means an operation of loosening and making fine (for example, into primary particles) a mass formed by fine particles aggregating (for example, secondary particles).

[0040] By setting the collision speed during disintegration to 92 m / s or less, it becomes easier to obtain a desired ratio of the second molding density to the first molding density. For example, by using an impact pulverizer or the like, disintegration can be performed at the above collision speed.

[0041] [Step of containing silicon or titanium] In addition to the above three steps, silicon or titanium may be further contained. As a method of containing silicon or titanium, for example, surface treatment with a silane coupling agent or a titanium coupling agent can be mentioned. Known materials can be used as the silane coupling agent and the titanium coupling agent, and the surface treatment can be performed on the pulverized aluminum hydroxide powder by a known method. As the addition amount of the coupling agent, the silicon content in the aluminum hydroxide powder is SiO 2 in terms of conversion value is 0.02 to 0.30% by mass, or the titanium content is TiO 2 in terms of conversion value is preferably added so as to be 0.01 to 0.30% by mass. The step of containing silicon or titanium may be carried out during any of the above three steps, or before or after any of the steps.

[0042] As the silane coupling agent or the titanium coupling agent, those containing an organic chain or ligand having a solubility parameter (SP value) of 14.0 to 21.0 MPa 0.5 are preferably used. Thereby, it can contribute to the improvement of the first molding density and the ratio of the second molding density to the first molding density. Examples of the silane coupling agent or the titanium coupling agent include, but are not limited to, hexyltrimethoxysilane, octadecyltrimethoxysilane, decyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-(acryloxy)propyltrimethoxysilane, 8-methacryloxyoctyltrimethoxysilane, 7-octenyltrimethoxysilane, isopropyltrisisostearoyl titanate, and isopropyltridodecylbenzenesulfonyl titanate. Note that as the above SP value, the value calculated by the method proposed by Fedors et al. for the SP value of the longest organic chain or ligand adjacent to the Si atom or Ti atom of the coupling agent was used. The method proposed by Fedors et al. is specifically the value obtained by referring to "ROBERT F. FEDORS, A Method for Estimating Both the Solubility Parameters and Molar Volumes of liquids, POLYMER ENGINEERING AND SCIENCE, 1974, Vol.14, No.2, p147-154" and converted to MPa 0.5 units. Hereinafter, unless otherwise specified, the "SP value" means the value calculated as described above.

[0043] As described above, an example of the method for producing aluminum hydroxide powder according to the embodiment of the present invention has been described. However, those skilled in the art who understand the desired properties of the aluminum hydroxide powder according to the embodiment of the present invention may perform trial and error to find a method for producing aluminum hydroxide powder having the desired properties according to the embodiment of the present invention, other than the above production method.

Examples

[0044] Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples. The embodiments of the present invention are not limited by the following examples, and can be implemented with appropriate modifications within the scope that can conform to the foregoing and following gists, and all of them are included in the technical scope of the embodiments of the present invention.

[0045] The raw aluminum hydroxide powder (D50: 81 μm, cumulative pore volume: 0.09 mL / g) was adjusted to a moisture content of 5 wt%, and continuously fed into a crusher (single-screw kneader) for crushing. The pressure of the crusher was set to 196.0 MPa by adjusting the feeding rate. Regarding the pressure of the crusher, the relationship between the pressing pressure and D90 was investigated by separately subjecting the same raw aluminum hydroxide powder to cold isostatic pressing and compression crushing, and the pressure of the crusher was simply determined from the D90 of the aluminum hydroxide powder after crushing. The obtained crushed product was dried at 120 °C and then fed into an impact crusher (free crusher, manufactured by Nara Machinery Co., Ltd.) for disintegration. The collision speed of the impact crusher was set to 46 m / s. To 100 parts by mass of the obtained disintegrated product, 2.5 parts by mass of a coupling agent solution (a mixture of 0.4 part by mass of water, 3.6 parts by mass of ethanol, and 1.0 part by mass of a silane coupling agent (octadecyltrimethoxysilane, manufactured by Tokyo Chemical Industry Co., Ltd., SP value: 17.0)) was added, and the mixture was mixed at 1000 rpm for 5 minutes using a planetary stirrer (manufactured by Shinki Co., Ltd., Awatori Renkatarou ARV-310). Then, it was dried (at 120 °C for 90 minutes) to obtain the aluminum hydroxide powder according to Example 1.

[0046] 2.0 parts by mass of a coupling agent solution using 8-methacryloyloxyoctyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., SP value: 18.7) was added, and the aluminum hydroxide powder of Example 2 was obtained in the same manner as in Example 1 for the rest.

[0047] 1.5 parts by mass of a coupling agent solution using 3-methacryloxypropyltrimethoxysilane (manufactured by Momentive, SP value: 19.4) was added, and the aluminum hydroxide powder of Example 3 was obtained in the same manner as in Example 1 for the rest.

[0048] The raw aluminum hydroxide powder (D50: 65 μm, cumulative pore volume: 0.14 mL / g) was adjusted to a moisture content of 5 wt%, continuously fed into a pulverizer (single-screw kneader), and pulverized. The pressure of the pulverizer was set to 196.0 MPa by adjusting the feeding rate. Regarding the pressure of the pulverizer, the relationship between the pressing pressure and D90 was investigated separately by subjecting the same raw aluminum hydroxide powder to cold isostatic pressing and compression pulverization, and the pressure of the pulverizer was simply determined from the D90 of the aluminum hydroxide powder after pulverization. The obtained pulverized product was dried at 120 °C, fed into an impact pulverizer (free pulverizer, manufactured by Nara Machinery Co., Ltd.), and disintegrated. The collision speed of the impact pulverizer was 91 m / s. To 9000 parts by mass of the obtained disintegrated product, 45 parts by mass of a coupling agent (3-methacryloxypropyltrimethoxysilane (manufactured by Momentive, SP value: 19.4)) was added, and the mixture was stirred at 130 °C for 20 minutes using a high-speed flow mixer (Kawata Co., Ltd., SMV-20) to obtain the aluminum hydroxide powder according to Example 4.

[0049] To the coupling agent solution, 1.5 parts by mass of a coupling agent solution of a mixture of isopropyl alcohol and a titanium coupling agent (isopropyltriisostearoyl titanate, manufactured by Ajinomoto Fine-Techno Co., Inc., SP value: 18.0) (isopropyl alcohol: titanium coupling agent = 4:1) was used, and the aluminum hydroxide powder of Example 5 was obtained in the same manner as in Example 1 for the rest.

[0050] Using 2.0 parts by mass of a coupling agent solution of a mixture of isopropyl alcohol and a titanium coupling agent (isopropyltridodecylbenzenesulfonyl titanate, manufactured by Ajinomoto Fine-Techno Co., Inc., SP value: 18.8) (isopropyl alcohol: titanium coupling agent = 4:1), the aluminum hydroxide powder of Example 6 was obtained in the same manner as in Example 1 for the rest.

[0051] The raw aluminum hydroxide powder (D50: 81 μm, cumulative pore volume: 0.01 mL / g) was subjected to a vibration mill (8 mmφ iron balls). To 100 parts by mass of the obtained pulverized material, 0.50 part by mass of a coupling agent (3-methacryloxypropyltrimethoxysilane (manufactured by Momentive, SP value: 19.4)) was added, and the mixture was mixed at 100 °C using a Henschel mixer to obtain the aluminum hydroxide powder of Comparative Example 1.

[0052] To a wet cake of a commercially available aluminum hydroxide powder (manufactured by Sumitomo Chemical Co., Ltd., CW-308, D50: 11 μm) adjusted to a moisture content of 5 wt%, a coupling agent (3-methacryloxypropyltrimethoxysilane (manufactured by Momentive, SP value: 19.4)) was added so that the addition amount relative to the aluminum hydroxide powder was 0.50% by mass, and silane coupling agent treatment was performed using a fluidized dryer at 120 °C to obtain the aluminum hydroxide powder of Comparative Example 2.

[0053] To a wet cake of a commercially available aluminum hydroxide powder (manufactured by Sumitomo Chemical Co., Ltd., CL-303, D50: 5.5 μm) adjusted to a moisture content of 20 wt%, a coupling agent (3-methacryloxypropyltrimethoxysilane (manufactured by Momentive, SP value: 19.4)) was added so that the addition amount relative to the aluminum hydroxide powder was 0.60% by mass, and silane coupling agent treatment was performed using a fluidized dryer at 120 °C to obtain the aluminum hydroxide powder of Comparative Example 3.

[0054] For the aluminum hydroxide powders of Examples 1 to 6 and Comparative Examples 1 to 3, the first molding density, the second molding density, the mass-based particle size distribution (including D50 and D90), the BET specific surface area, and the silicon, titanium, and sodium contents (in terms of SiO 2 ·TiO 2 ·Na 2 O conversion) were determined by the following method.

[0055] [First molding density] 3.00 g of the aluminum hydroxide powder was placed in a die for uniaxial molding with an inner diameter of 20.0 mm, and using a universal material testing machine (manufactured by A&D Company, TENSILON RTG-1310), the aluminum hydroxide powder was compression-filled at a compression speed of 1 mm / min until a pressure of 10 MPa was reached, and the ratio of weight / volume was taken as the first molding density.

[0056] [Second molding density] 3.00 g of aluminum hydroxide powder was placed into a mold for uniaxial molding with an inner diameter of 20.0 mm, and using a universal material testing machine (manufactured by A&D Company, TENSILON RTG-1310), the aluminum hydroxide powder was compression-filled until the pressure reached 0.5 MPa at a compression rate of 1 mm / min, and the weight / volume ratio was taken as the second molding density.

[0057] [Mass-based particle size distribution (including D50 and D90)] Aluminum hydroxide powder was added into isopropyl alcohol, and ultrasonic waves with an output of 25 W were irradiated for 120 seconds to disperse the aluminum hydroxide powder in an aqueous solution. Then, using a laser scattering particle size distribution analyzer, the mass-based particle size distribution (including D50 and D90) was determined. The particle size distribution was obtained by logarithmically dividing the range of particle diameters from 0.02 μm to 2000 μm into 132 parts and measuring the mass of aluminum hydroxide having the particle diameter in each section. Considering the difference between instruments and the consistency with this example, Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) was used as the laser scattering particle size distribution analyzer. Also, during the measurement of the particle size distribution, the concentration of the aluminum hydroxide powder was appropriately adjusted to the measurable concentration of the above-mentioned measuring device before measurement.

[0058] [BET specific surface area] According to the method specified in JIS-Z-8830:2013, using a fully automatic specific surface area analyzer (manufactured by Mountech Co., Ltd., Macsorb HM-1201), the BET specific surface area was determined by the nitrogen adsorption method.

[0059] [Silicon, titanium, sodium content (SiO 2 ·TiO 2 ·Na 2 O conversion)] An aluminum hydroxide powder was dissolved in an aqueous solution of an inorganic acid to prepare an aqueous solution, and then the contents of silicon, titanium, and sodium were determined using an ICP emission spectroscopic analyzer. Specifically, the intensities of the wavelengths of silicon (251.611 nm), titanium (334.940 nm), and sodium (589.592 nm) were measured, and the SiO 2 , TiO 2 , and Na 2 O were converted. The masses of SiO 2 , TiO 2 , and Na 2 O were calculated, and the ratios of the masses of the SiO 2 , TiO 2 , and Na 2 O to the mass of the dissolved aluminum hydroxide powder were taken as the contents (mass %) of silicon, titanium, and sodium, respectively.

[0060] Furthermore, the resin viscosity was determined by the following method. 6.25 parts by mass of an aluminum hydroxide powder and 1.56 parts by mass of a bisphenol A type epoxy resin mixture (AQ010-8140, room temperature curing resin 53 type main agent) were mixed at 1000 rpm for 3 minutes using a planetary stirrer (manufactured by Shinki Co., Ltd., Awatori Rentaro ARV-310) to obtain a compound. A parallel plate with a diameter of 30 mm was attached to a dynamic viscoelasticity measuring device (Rheosol-G3000), and the above compound was set here. After leaving it to stand for 10 minutes under the conditions of a parallel plate gap of 0.50 mm and a temperature of 100 °C, the resin viscosity at a shear rate of 40 s -1 was measured. Those with a high resin viscosity and unable to lower the parallel plate to a gap of 0.50 mm were considered unmeasurable. The results are summarized in Table 1 below. In Table 1, the "SiO 2 content" is the silicon content expressed in terms of the SiO 2 converted value, the "TiO 2 content" is the titanium content expressed in terms of the TiO 2 converted value, and the "Na 2 O content" is the Na 2It is the sodium content expressed in terms of the O conversion value. In Table 2, "-" in the column of "Second Peak" means that the second peak did not exist. In Table 1, "Unmeasurable" in the column of "Resin Viscosity" means that the viscosity could not be measured due to high viscosity.

[0061]

Table 1

[0062] From the results in Table 1, the following considerations can be made. Examples 1 to 6 in Table 1 all satisfy all the requirements defined in the embodiments of the present invention. The resin viscosity is 35 Pa·s or less, and the increase in resin viscosity can be sufficiently suppressed. Also, since D90 is less than 100 μm, it is a preferable example in that it can sufficiently suppress appearance defects when filled in a resin molded body and can easily ensure sufficient strength of the resin molded body. On the other hand, Comparative Examples 1 to 3 are examples that do not satisfy the requirements defined in the embodiments of the present invention. In particular, the resin viscosity exceeds 35 Pa·s, and the increase in resin viscosity cannot be sufficiently suppressed.

[0063] In Comparative Example 1, a vibration mill process was performed in the production process of aluminum hydroxide powder, and since the ratio of the second molding density to the first molding density was less than 0.875, the resin viscosity exceeded 35 Pa·s, and the increase in resin viscosity could not be sufficiently suppressed.

[0064] In Comparative Example 2, since the first molding density was less than 1.60 g / cm 3 the resin viscosity exceeded 35 Pa·s. Probably, in the production process of aluminum hydroxide powder, since the grinding process was not performed, etc., the first molding density became less than 1.60 g / cm 3 and it is considered that the increase in resin viscosity could not be sufficiently suppressed.

[0065] In Comparative Example 3, the first molding density was 1.60 g / cm 3Since it was less than that, the resin viscosity exceeded 35 Pa·s. Probably, in the manufacturing process of the aluminum hydroxide powder, since at least the D50 of the raw material aluminum was less than 10 μm, the first molding density became less than 1.60 g / cm 3 and it is considered that the increase in the resin viscosity could not be sufficiently suppressed.

Claims

Claim 1 The first molding density, which is the molding density when molded at 10 MPa, is 1.60 to 2.20 g / cm ３ and The ratio of the second molding density, which is the molding density when molded at 0.5 MPa, to the first molding density is 0.875 to 0.970, in the mass-based particle size distribution, the particle diameter at which the cumulative frequency from the fine particle side is 50% by mass is 30 μm or less, the BET specific surface area is 2.0 m2 / g or less, an aluminum hydroxide powder having one or two peaks in the particle diameter range of 1 to 200 μm in the mass-based particle size distribution. Claim 2 The aluminum hydroxide powder according to claim 1, containing silicon or titanium. Claim 3 The silicon content is 0.02 to 0.30% by mass in terms of SiO ２ converted value, and The titanium content is TiO ２ The aluminum hydroxide powder according to claim 2, wherein the conversion value is 0.01 to 0.30% by mass. Claim 4 The aluminum hydroxide powder according to any one of claims 1 to 3, wherein the particle diameter (D90) of 90% by mass is less than 100 μm. Claim 5 When having one peak in the particle diameter range of 1 to 200 μm in the mass-based particle size distribution, the frequency of the peak is 4.0% by mass or more, When having two peaks in the particle diameter range of 1 to 200 μm in the mass-based particle size distribution, the frequency of one peak is 4.0% by mass or more, and the frequency of the other peak is more than 0% by mass and 4.0% by mass or less. The aluminum hydroxide powder according to any one of claims 1 to 4.

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