KR20230008606A - Aluminum hydroxide powder and method for producing the same - Google Patents

Abstract

Provided are aluminum hydroxide powder capable of sufficiently suppressing an increase in viscosity when added to a resin and a method for producing the same. In the aluminum hydroxide powder, density is 1.59 to 2.00 g/cm when molded at 10 MPa, and a ratio of the diffraction intensity of a plane (002) to that of a plane (110) in the XRD pattern is 2.0 to 7.5.

Description

Aluminum hydroxide powder and its manufacturing method {ALUMINUM HYDROXIDE POWDER AND METHOD FOR PRODUCING THE SAME}

The present disclosure relates to aluminum hydroxide powder and methods of making the same.

Demand for aluminum hydroxide powder is increasing as a filler for resin moldings (sealing materials, thermal interface materials, artificial marble, etc.).

For example, Patent Document 1 discloses a method for producing aluminum hydroxide for use as a filler, characterized in that raw material aluminum hydroxide is pulverized with a screw-type kneader having a compression capacity of 5 to 500 kgf/cm 2 .

JP 2001-322813 A

However, in the prior art disclosed in Patent Literature 1, it has been found that there is a possibility that the aluminum hydroxide powder is easily thickened when added to the resin.

The present invention has been made in view of such a situation, and one of its objects is to provide an aluminum hydroxide powder capable of sufficiently suppressing the increase in viscosity when added to a resin and a method for producing the same.

Aspect 1 of the present invention,

The density when molded at 10 MPa is 1.59 to 2.00 g / cm 3,

It is an aluminum hydroxide powder whose 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.

Aspect 2 of the present invention,

It is the aluminum hydroxide powder of aspect 1 whose 90 mass % particle diameter (D90) is less than 100 micrometers.

Aspect 3 of the present invention,

It has one or two peaks in the particle size range of 1 to 200 μm in the mass-based particle size distribution, but in the case of one peak, the frequency of the peak is 4.0% by mass or more, and in the case of two peaks, one peak The frequency of 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 aspect 1 or 2.

Aspect 4 of the present invention,

Aluminum hydroxide powder having a 50% by mass particle diameter (D50) of 10 to 200 μm and a cumulative volume of pores of 0.05 to 1 μm in radius of 0.01 to 1 ml / g is pulverized at a pressure of 49.0 to 294.0 MPa, It is a manufacturing method of aluminum hydroxide powder including crushing at a collision speed of 92 m/sec or less.

According to an embodiment of the present invention, it is possible to provide an aluminum hydroxide powder capable of sufficiently suppressing an increase in viscosity when added to a resin and a method for producing the same.

The present inventors studied from various angles in order to realize an aluminum hydroxide powder capable of sufficiently suppressing an increase in viscosity when added to resin (hereinafter also referred to as "resin viscosity"). As a result, the ratio of the diffraction intensity of the (002) plane to the diffraction intensity of the (110) plane in the density when molded at 10 MPa (hereinafter also referred to as "molding density") and the XRD pattern (hereinafter referred to as "(002) / (110) also referred to as "diffraction intensity ratio") was found to be able to sufficiently suppress the increase in resin viscosity by controlling it within a predetermined range.

In order to control the molding density and the (002)/(110) diffraction intensity ratio within a predetermined range, the particle size and pore volume of the raw material aluminum hydroxide powder are controlled within a predetermined range, and at the same time, a pressure higher than that of the prior art (500 to 3000 kgf / cm 2, That is, it was found that it is important to grind at 49.0 to 294.0 MPa) and to grind at a relatively weak impact speed of 92 m/sec or less.

Below, the detail of each requirement prescribed|regulated by embodiment of this invention is shown.

<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, and the diffraction intensity of the (002) plane relative to the diffraction intensity of the (110) plane in the XRD pattern. The ratio of is from 2.0 to 7.5. Thereby, the rise of resin viscosity can fully be suppressed.

If the molding density is less than 1.59 g/cm 3 , the resin viscosity increases. The upper limit of the molding density is not particularly limited, but, for example, to exceed 2.00 g/cm 3 , it is necessary to set more detailed manufacturing conditions, and considering productivity, it is preferably set to 2.00 g/cm 3 or less.

In addition, molding density shall be calculated|required as follows.

3.00 g of aluminum hydroxide powder was put into a cylindrical uniaxial molding mold with an inner diameter of 20.0 mm, and the aluminum hydroxide powder was compressed at a compression speed of 1 mm/ Compression filling is performed until the pressure reaches 10 MPa per minute, and the weight/volume ratio is used as the molding density.

When the (002)/(110) diffraction intensity ratio exceeds 7.5, the aluminum hydroxide powder, for example, may have a shape close to a normal sphere, but becomes a distorted shape like a plate, and the resin viscosity increases. Preferably, the (002)/(110) diffraction intensity ratio is 6.0 or less. The lower limit of the (002)/(110) diffraction intensity ratio is not particularly limited, but more detailed manufacturing conditions are required to set the (002)/(110) diffraction intensity ratio to less than 2.0. It is desirable to set it above.

In addition, the (002)/(110) diffraction intensity ratio is determined as follows.

After compacting and filling aluminum hydroxide powder into a glass cell for measurement, using a powder X-ray diffraction measuring device (e.g., RINT-2000 manufactured by Rigaku Corporation), step width 0.02 deg, scan speed 0.04 XRD patterns are measured at deg/sec, an accelerating voltage of 40 kV, and an accelerating current of 30 mA. As an X-ray source, Cu-Kα is used. In the obtained XRD pattern, the peak appearing at the position of 2θ = 18.3 ° is the peak of the (002) plane, the peak appearing at the position of 2θ = 20.3 ° is the peak of the (110) plane, and the peak of the (110) plane The ratio of the diffraction intensity (peak height) of the (002) plane peak to the diffraction intensity (peak height) of is the (002)/(110) diffraction intensity ratio.

The aluminum hydroxide powder according to the embodiment of the present invention has a 90 mass% particle diameter (that is, a particle diameter at which the cumulative frequency from the fine particle side is 90 mass% in the mass-based particle size distribution, also referred to as D90) of 100 Preferably less than μm. This makes it possible to sufficiently suppress the appearance defect when the aluminum hydroxide powder is filled into the resin molded body, and it is easy to sufficiently secure the strength of the resin molded body. Preferably, the D90 is 90 μm or less, more preferably 65 μm or less, still more preferably 45 μm or less.

It is preferable that the aluminum hydroxide powder according to the embodiment of the present invention has a D90 of 20 μm or more. This can suppress the dispersion defect at the time of dispersing the aluminum hydroxide powder in the liquid.

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-based particle size distribution. This can suppress appearance defects when the aluminum hydroxide powder is filled into the resin molded body, and can also suppress dispersion defects when the aluminum hydroxide powder is dispersed in a liquid. When there is one peak, the frequency of the peak may be 4.0% by 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 to have only one peak in the particle size range of 1 to 200 μm in the mass-based particle size distribution. This makes it possible to further suppress poor appearance and poor dispersion of the resin molded body.

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 of less than 1 μm and greater than 200 μm in the mass-based particle size distribution, and the frequency of the peaks is It may be more than 0% by mass and 0.5% by mass or less, or it is not necessary to have a peak in the particle diameter range of less than 1 μm and more than 200 μm.

Aluminum hydroxide powder according to an embodiment of the present invention has a 50% by mass particle size (that is, a particle size at which the cumulative frequency from the fine particle side is 50% by mass in the mass-based particle size distribution, also referred to as D50) of 30 It is preferable that it is micrometer or less. This makes it possible to suppress poor appearance when the aluminum hydroxide powder is filled into the resin molded body, and also to ensure the strength of the resin molded body.

It is preferable that the aluminum hydroxide powder according to the embodiment of the present invention has a D50 of 7 μm or more. This can suppress the dispersion defect at the time of dispersing the aluminum hydroxide powder in the liquid.

In addition, the mass-based particle size distribution (including D50 and D90) is determined as follows. Aluminum hydroxide powder was added to a 0.2% by mass aqueous solution of sodium hexametaphosphate, and ultrasonic waves with an output of 25 W were irradiated for 120 seconds to disperse the aluminum hydroxide powder in the aqueous solution. Using a laser scattering type particle size distribution measuring device, particle size distribution based on mass was obtained. (including D50 and D90). The particle size distribution is obtained by dividing the range of particle diameters from 0.02 μm to 2000 μm by 132 on a logarithmic scale, and measuring the mass of aluminum hydroxide having particle diameters in each section. In addition, as a laser scattering type particle size distribution measuring device, considering the difference between instruments and compatibility with the present embodiment, etc., Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) or a device equivalent thereto is used. it is desirable Further, in the measurement of the particle size distribution, it is preferable to measure the concentration after appropriately adjusting the concentration of the aluminum hydroxide powder to the measurable concentration of the measuring device.

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. This can suppress the dispersion defect at the time of dispersing the aluminum hydroxide powder in the liquid. In addition, the BET specific surface area is determined by nitrogen adsorption method using a fully automatic specific surface area measuring device (e.g., Macsorb HM-1201 manufactured by Mountech) according to the method specified in JIS-Z-8830:2013. .

Aluminum hydroxide powder according to an embodiment of the present invention may include Na ₂ O as an impurity. It is preferable to make content _of Na2O into 0.13 mass % or less, for example. Thereby, the deterioration of resin and the fall of insulating property at the time of filling a resin molded object can be suppressed. Here, the content of Na ₂ O shall be determined using an ICP emission spectrometer after dissolving aluminum hydroxide powder in an aqueous solution of an inorganic acid to prepare an aqueous solution. Specifically, the intensity of the sodium wavelength (589.592 nm) is measured, converted to Na ₂ O, the mass of Na ₂ O is calculated, and the ratio of the mass of the Na ₂ O to the mass of the dissolved aluminum hydroxide powder is taken as the Na ₂ O content (mass %). In addition, the aluminum hydroxide powder according to the embodiment of the present invention may contain unavoidable impurities in addition to Al(OH) ₃ and Na ₂ O. As an unavoidable impurity, the incorporation of elements, etc., is allowed depending on the circumstances of raw materials, materials, manufacturing facilities, etc.

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 a resin molded body (sealing material, thermal interface material, artificial marble, etc.). Examples of applicable resins include thermosetting resins such as unsaturated polyester resins, epoxy resins, phenol resins, and polyurethane resins, polyethylene, polypropylene, copolymers of ethylene and propylene, ethylene and/or propylene, and Polyolefins represented by copolymers of other α-olefins such as butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, 4-methylpentene-1 and decene-1, and styrene (co)polymer, methyl methacrylate (co)polymer, polyamide, polycarbonate, ethylene-vinyl acetate copolymer, polyacetal, acrylonitrile-butadiene-styrene copolymer, polyphenylene oxide, poly and thermoplastic resins such as ether sulfone, polyarylate, polyether ether ketone, and polymethylpentene. The aluminum hydroxide powder according to the embodiment of the present invention is not limited to the above resins, and can be used as other synthetic resins, natural resins, or fillers such as paper.

<2. Method for producing aluminum hydroxide powder>

In the method for producing aluminum hydroxide powder according to an embodiment of the present invention, (a) the 50% by mass particle diameter (D50) is 10 to 200 μm, and the cumulative volume of pores with a radius of 0.05 to 1 μm is 0.01 to 1 ml / A step of preparing gram aluminum hydroxide powder, (b) a step of crushing at a pressure of 49.0 to 294.0 MPa, and (c) a step of crushing at a collision speed of 92 m/sec or less. Hereinafter, each process is explained in detail.

[(a) Process of Preparing Aluminum Hydroxide Powder]

First, an aluminum hydroxide powder serving as a raw material (hereinafter, also referred to as "raw material aluminum hydroxide powder") is prepared. The raw material aluminum hydroxide powder has a 50% by mass particle diameter (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 “accumulated pore volume”) of 0.01 to 1 ml/g. There is a need. This makes it easier to obtain a desired molding density. Preferably, the accumulated pore volume is 0.02 to 1 ml/g. This makes it easier to obtain a desired D90 and also easier to obtain an aluminum hydroxide powder having a desired mass-based particle size distribution.

When D50 is less than 10 μm or more than 200 μm, and/or the accumulated pore volume is less than 0.01 ml/g or more than 1 ml/g, it becomes difficult to obtain a desired molding density.

In addition, the accumulated pore volume is obtained as follows.

The aluminum hydroxide powder is dried at 120°C for 4 hours to remove adsorbed moisture. After that, about 0.5 to 0.6 g is weighed with a precision scale, and filled into a measuring cell having a diameter of 15 mm and a height of 24 mm. This measurement cell is set in an automatic porosimeter (for example, Autopore III9420, manufactured by Micromeritics), and the measurement is divided into a low pressure side (1 to 10000 psi) and a high pressure side (10000 to 60000 psi). By summing these measurement data, the pore volume distribution in the region of 0.002 µm or more and 100 µm or less in pore radius is obtained, and the cumulative volume in the region of 0.05 µm or more and 1.0 µm or less in pore radius is calculated.

The crystal structure of the raw material aluminum hydroxide powder is, for example, a Gibbsite type, a Bayerite type or the like, preferably a gibbsite type.

The raw material aluminum hydroxide powder is obtained by adding seed crystals to a supersaturated sodium aluminate solution, hydrolyzing it while stirring, precipitating aluminum hydroxide, filtering and washing the obtained aluminum hydroxide, and drying it. can be manufactured Here, by appropriately adjusting the precipitation conditions (and/or partially dissolving the precipitated material, and/or pulverizing or pulverizing the precipitated material), the raw material aluminum hydroxide powder having the particle diameter and the accumulated pore volume is obtained. is obtained In addition, commercially available aluminum hydroxide powder may be used as long as it satisfies the above particle diameter and pore volume.

[(b) Step of crushing at a pressure of 49.0 to 294.0 MPa]

Next, the raw material aluminum hydroxide powder is pulverized at a pressure of 49.0 to 294.0 MPa. Here, "crushing" means an operation of adding a certain energy to solid particles (eg, primary particles) of a certain size to make them smaller than the original size.

If the pressure during pulverization is less than 49.0 MPa, the desired molding density cannot be obtained. Preferably it is more than 49.0 Mpa, More preferably, it is 68.6 Mpa or more. The upper limit of the pressure at the time of grinding is not particularly limited, but considering productivity, it is preferable to set it to 294.0 MPa or less.

Examples of the milling machine for pulverizing with the pressure include a coneder, an onlator, a self-cleaning kneader, a gear compounder, a single-screw kneader, and a twin-screw kneader. These devices may be used individually by 1 type, or may be used in combination of 2 or more types. In addition, either a batch type or a continuous type of grinder can be applied, but from the viewpoint of reducing the grinding energy per unit weight, a continuous type is preferable. When using a continuous grinder, the raw material aluminum hydroxide in the grinder does not necessarily have to be entirely ground, and, for example, the degree of grinding may be sequentially increased in the conveying direction (axial direction) of the raw material aluminum hydroxide. In the case of a screw type kneader, the compression capacity can be adjusted by, for example, the shape, length or number of rotations of the screw, the number of rotations of the rotor (acting to transfer the raw material to the screw), and the like.

Inside the grinder, raw material aluminum hydroxide powder exists as a solid phase, and usually, air or the like exists as a gas phase, and water or the like exists as a liquid phase. Since their state in the pulverizer at the time of pulverization sometimes affects the physical properties of the aluminum hydroxide powder obtained by pulverization, pulverization is a solid, liquid, and gaseous filling form (i) solid and gaseous phases are continuous and liquid In this substantially non-existent dry state, (ii) a pendular state in which the solid phase and the gas phase are continuous and the liquid phase is discontinuous, or (iii) a funicular I state in which the solid phase, gas phase and liquid phase are continuous it is desirable This type of filling constitutes a mixed system that is crumbly to crumbly in appearance.

Grinding is preferably performed after adjusting the liquid content 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. Adjustment of the liquid content ratio may be performed by, for example, drying the raw material aluminum hydroxide powder or adding a liquid such as water or alcohol. The preferred solution content is not unique because it varies depending on the particle size distribution of the raw material aluminum hydroxide, etc., 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. more than % When the liquid content ratio is too high, it becomes difficult to efficiently pulverize the raw material aluminum hydroxide.

When a liquid such as water is added during pulverization or the raw material aluminum hydroxide powder containing water or the like 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, when pulverizing is performed with a continuous pulverizer, a method of heating a part of the pulverizer.

[(c) Process of crushing at a collision speed of 92 m/sec or less]

After the step (b), crushing is performed at a collision speed of 92 m/sec or less. Here, “pulverization” refers to an operation of dissolving fine particles into a single lump (eg, secondary particles) to make them fine (eg, primary particles).

If the collision speed at the time of disintegration exceeds 92 m/sec, the desired (002)/(110) diffraction intensity ratio cannot be obtained. For example, by using an impact type grinder or the like, crushing can be performed at the above collision speed.

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

[Example]

Hereinafter, embodiments of the present invention will be described in more detail by giving examples. Embodiments of the present invention are not limited by the following examples, and can be implemented with appropriate changes within a range consistent with the above-described and later-described intent, and all of these are technical aspects of the embodiments of the present invention. included in the scope

The raw material aluminum hydroxide powder (D50: 81 μm, accumulated pore volume: 0.09 ml/g) was adjusted to a moisture content of 5% by weight, and continuously introduced into a grinder (single screw type kneader) to pulverize. The pressure of the grinder was set to 196.0 MPa by adjusting the feed rate. In addition, regarding the pressure of the grinder, the same raw material aluminum hydroxide powder is compressed and pulverized in a cold isostatic pressure press to investigate the relationship between the press pressure and D90, and the pressure of the grinder is simply obtained from the D90 of the aluminum hydroxide powder after pulverization. .

The resulting pulverized product was dried at 120° C., put into an impact mill (freedom pulverizer, manufactured by Nara Machinery Co., Ltd.) and pulverized to obtain aluminum hydroxide powder of Example 1. The impact speed of the impact mill was 46 m/sec.

Moreover, from the manufacturing method of the said Example 1, each condition was changed as shown in Table 1 below, and the aluminum hydroxide powder of Examples 2-4 and Comparative Examples 1-2 was obtained. In addition, commercially available aluminum hydroxide powder was used in Comparative Example 3 (SUMITOMO CHEMICAL COMPANY, CW-308), Comparative Example 4 (Sumitomo Chemical, C-305), Comparative Example 5 (Sumitomo Chemical, CM -3080).

For the aluminum hydroxide powders of Examples 1 to 4 and Comparative Examples 1 to 5, molding density, (002)/(110) diffraction intensity ratio, mass-based particle size distribution (including D50 and D90), BET by the following methods The specific surface area and Na ₂ O content were obtained.

[Forming Density]

3.00 g of aluminum hydroxide powder was put into a cylindrical uniaxial molding mold with an inner diameter of 20.0 mm, and using a universal testing machine (manufactured by A&D, TENSILON RTG-1310), the aluminum hydroxide powder was compressed at a compression speed of 1 mm/min at a rate of 10 MPa. Compression filling was performed until the pressure was reached, and the weight/volume ratio was used as the molding density.

[(002)/(110) diffraction intensity ratio]

After compacting and filling the aluminum hydroxide powder into a glass cell for measurement, using a powder X-ray diffraction measuring device (Rigaku Co., Ltd., RINT-2000), step width 0.02deg, scan speed 0.04deg/sec, acceleration voltage 40kV , XRD patterns were measured at an accelerating current of 30 mA. As an X-ray source, Cu-Kα was used. In the obtained XRD pattern, the peak appearing at the position of 2θ = 18.3 ° is the peak of the (002) plane, and the peak appearing at the position of 2θ = 20.3 ° is the peak of the (110) plane. The ratio of the diffraction intensity (peak height) of the (002) plane peak to the diffraction intensity (peak height) of the peak was taken as the (002)/(110) diffraction intensity ratio.

[Particle size distribution by mass (including D50 and D90)]

Aluminum hydroxide powder was added to a 0.2% by mass aqueous solution of sodium hexametaphosphate, and ultrasonic waves with an output of 25 W were irradiated for 120 seconds to disperse the aluminum hydroxide powder in the aqueous solution. Distributions (including D50 and D90) were obtained. The particle size distribution was determined by dividing the range of particle diameters from 0.02 μm to 2000 μm by 132 on a logarithmic scale, and measuring the mass of aluminum hydroxide having particle diameters in each section. As a laser scattering type particle size distribution measuring device, Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) was used. Further, in the measurement of particle size distribution, the concentration of the aluminum hydroxide powder was appropriately adjusted to the measurable concentration of the measuring device, and then the measurement was performed.

[BET specific surface area]

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

[Na ₂ O content]

After preparing an aqueous solution by dissolving aluminum hydroxide powder in an aqueous solution of an inorganic acid, the Na ₂ O content was determined using an ICP emission spectrometer. Specifically, the intensity of the sodium wavelength (589.592 nm) is measured, converted into Na ₂ O, the mass of Na ₂ O is calculated, and the ratio of the mass of the Na ₂ O to the mass of the dissolved aluminum hydroxide powder was taken as the Na ₂ O content (mass %).

In addition, 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 a bisphenol A type epoxy resin mixture (AQ010-8140, room temperature curing resin 53 type main material) were mixed with a planetary stirrer (made by Shinki Corporation, Awatori Rentaro) ARV-310) was mixed at 1000 rpm for 3 minutes to obtain a compound. A parallel plate having a diameter of 30 mm was mounted on a dynamic viscoelasticity measuring device (Rheosol-G3000), and the compound was set there. The resin viscosity was measured at a shear rate of 40 s ⁻¹ after allowing the parallel plate to stand for 10 minutes under conditions of a gap of 0.50 mm and a temperature of 100° C.

The results are summarized in Table 2 below. In Table 2, "-" in the column of "second peak" means that the second peak did not exist.

From the results of Table 2, the following can be considered. Examples 1 to 4 in Table 2 are all examples satisfying all of the requirements stipulated in the embodiment of the present invention, and the increase in the resin viscosity was sufficiently suppressed as the resin viscosity was 10 Pa·s or less. Among them, Examples 1 to 3 were preferred examples from the viewpoint that, since the D90 was less than 100 μm, defects in appearance when filled into a resin molded body could be sufficiently suppressed, and the strength of the resin molded body was sufficiently secured. . In Example 4, since the accumulated pore volume of the raw material aluminum hydroxide powder was less than 0.02 ml/g, the D90 was 100 µm or more.

On the other hand, Comparative Examples 1 to 5 are examples that do not satisfy the requirements stipulated in the embodiment of the present invention, and the increase in the resin viscosity could not be sufficiently suppressed because the resin viscosity was more than 10 Pa·s.

In Comparative Example 1, since the collision speed during disintegration was more than 92 m/sec, the (002)/(110) diffraction intensity ratio was more than 7.5, and the resin viscosity was more than 10 Pa·s.

In Comparative Example 2, since the pressure during grinding was less than 49.0 MPa, the molding density was less than 1.59 g/cm 3 and the resin viscosity was more than 10 Pa·s.

In Comparative Examples 3 and 4, since the molding density was less than 1.59 g/cm 3 , the resin viscosity was more than 10 Pa·s.

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

Claims (4)

As aluminum hydroxide powder
The density when molded at 10 MPa is 1.59 to 2.00 g / cm 3,
The aluminum hydroxide powder whose 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 aluminum hydroxide powder according to claim 1, wherein the 90% by mass particle diameter (D90) is less than 100 µm. According to claim 1 or 2,
In the mass-based particle size distribution, it 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,
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, aluminum hydroxide powder. As a method for producing aluminum hydroxide powder,
Aluminum hydroxide powder having a 50% by mass particle diameter (D50) of 10 to 200 μm and a cumulative volume of pores of 0.05 to 1 μm in radius of 0.01 to 1 ml / g is pulverized at a pressure of 49.0 to 294.0 MPa, A method for producing aluminum hydroxide powder, comprising crushing at a collision speed of 92 m/sec or less.