Inorganic aluminum compound powder

Abstract

To provide an inorganic aluminum compound powder that enables sufficient suppression of viscosity increase upon addition to a resin.SOLUTION: An inorganic aluminum compound powder satisfying the following formula (1): V(cm3 / g)×D50(μm)≥0.11, where V represents the specific mesopore volume (cm3 / g) of the inorganic aluminum compound powder, and D50 represents a particle diameter (μm) at which the cumulative frequency from the fine-particle side reaches 50 vol% in a volume-based particle size distribution of the inorganic aluminum compound powder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to inorganic aluminum compound powders. [Background technology]

[0002] It is known that inorganic aluminum compound powders such as aluminum hydroxide powder can be used as fillers for resin molded products (for example, Patent Documents 1 and 2). Resin molded products containing inorganic aluminum compound powders can be used as thermal interface materials (TIMs) that fill gaps between electronic components and heat sinks. Patent Document 1 discloses a method for producing aluminum hydroxide powder that can be highly filled into a resin molded body, characterized in that raw material aluminum hydroxide is pulverized. Patent Document 2 describes a filler to be filled into a resin molded body, which has a density of 1.59 to 2.00 g / cm when molded at 10 MPa. 3 and an aluminum hydroxide powder in which 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 is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-322813 [Patent Document 2] Japanese Patent Publication No. 2023-009506 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, with the trend toward miniaturization and high-density packaging of electronic devices, resin molded products with better thermal conductivity are desired, and inorganic aluminum compound powders that can achieve higher filling rates are needed. However, when the inorganic aluminum compound powder is highly filled into a resin material, there is a problem that the viscosity of the kneaded product increases, resulting in a decrease in the moldability of the resin molded product.

[0005] The present disclosure has been made in view of the above circumstances, and one of its objects is to provide an inorganic aluminum compound powder that can sufficiently suppress an increase in viscosity when added to a resin. [Means for solving the problem]

[0006] Aspect 1 of the present invention is The inorganic aluminum compound powder satisfies the following formula (1): V×D50≧0.11 (1) where: V is the specific mesopore volume (cm) of the inorganic aluminum compound powder. 3 / g), D50 is the particle size (μm) at which the cumulative frequency from the fine particle side in the volume-based particle size distribution of the inorganic aluminum compound powder is 50% by volume.

[0007] Aspect 2 of the present invention is The inorganic aluminum compound powder according to embodiment 1, which is an aluminum hydroxide powder.

[0008] Aspect 3 of the present invention is The inorganic aluminum compound powder according to aspect 2 satisfies the following formula (2): 2.0≦I 002 / I 110 ≦6.0 (2) where: I 110 and I 002 are the peak diffraction intensities of the (110) and (002) planes of aluminum hydroxide in the XRD pattern, respectively.

[0009] A fourth aspect of the present invention is D50 is 5 μm or more and 130 μm or less, BET specific surface area is 0.5m 2 / g or more. [Effects of the Invention]

[0010] According to an embodiment of the present invention, it is possible to provide an inorganic aluminum compound powder that can sufficiently suppress an increase in viscosity when added to a resin. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a graph in which the XRD index is plotted on the vertical axis and the structural parameter (V×D50) is plotted on the horizontal axis for inorganic aluminum compound powders (aluminum hydroxide) of Examples and Comparative Examples. [Figure 2A] FIG. 2A is an SEM image of inorganic aluminum compound particles constituting the inorganic aluminum compound powder (aluminum hydroxide powder) of Example 1. [Figure 2B] FIG. 2B is an SEM image of inorganic aluminum compound particles constituting the inorganic aluminum compound powder (aluminum hydroxide powder) of Example 3. [Figure 3A] FIG. 3A is an SEM image of inorganic aluminum compound particles constituting the inorganic aluminum compound powder (aluminum hydroxide powder) of Comparative Example 1. [Figure 3B] FIG. 3B is an SEM image of inorganic aluminum compound particles constituting the inorganic aluminum compound powders (aluminum hydroxide powders) of Comparative Examples 2 and 3. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present inventors have investigated from various angles in order to realize an inorganic aluminum compound powder that can sufficiently suppress an increase in viscosity when added to a resin (hereinafter also referred to as "resin viscosity"). As a result, the specific mesopore volume V (cm) of the inorganic aluminum compound powder has been found to be 3 / g) and the particle size D50 (μm) at which the cumulative frequency from the fine particle side becomes 50% by volume in the volume-based particle size distribution of the inorganic aluminum compound powder (V × D50 (μm cm 3 / g)) within a predetermined range, the increase in resin viscosity can be sufficiently suppressed, and this finding led to the completion of the present invention.

[0013] Details of the inorganic aluminum compound powder according to the embodiment of the present invention will be described below.

[0014] <1. Inorganic aluminum compound powder> The inorganic aluminum compound powder according to an embodiment of the present invention satisfies the following formula (1). V×D50≧0.11 (1) where: V is the specific mesopore volume (cm) of the inorganic aluminum compound powder. 3 / g), D50 is the particle size (μm) at which the cumulative frequency from the fine particle side in the volume-based particle size distribution of the inorganic aluminum compound powder is 50% by volume.

[0015] As used herein, the specific mesopore volume V (cm 3 / g) and D50 (μm) (V × D50 (μm cm 3 / g)) is called the "structural parameter." The structural parameter is an index that indirectly indicates the roundness of the inorganic aluminum compound particles that make up the inorganic aluminum compound powder, and when the structural parameter is large, it can be said that the inorganic aluminum compound particles are rounded (with few angular protrusions). Inorganic aluminum compound powders made up of rounded inorganic aluminum compound particles tend to be able to reduce resin viscosity. Therefore, when the structural parameter (V × D50) of an inorganic aluminum compound powder is 0.11 (μm cm 3 / g) or more, the resin viscosity can be controlled within an appropriate range.

[0016] To explain the significance of formula (1), first, the characteristics of the surface morphology of the inorganic aluminum compound powder according to the embodiment of the present invention and a method for producing the inorganic aluminum compound powder will be described.

[0017] 2A and 2B are SEM images of inorganic aluminum compound powders according to embodiments (aluminum hydroxide powders of Examples 1 and 3), which show the surface shape of inorganic aluminum compound particles (aluminum hydroxide particles) 10 constituting the inorganic aluminum compound powder. 3A and 3B are SEM images of raw material powders (aluminum hydroxide powders of Comparative Examples 1 to 3), which are the raw material for the inorganic aluminum compound powder, which show the surface shape of raw material particles 100 constituting the raw material powder.

[0018] The raw material particle 100 shown in the upper SEM image of Figure 3A (magnification: 500x) was produced by a conventional manufacturing method and is basically an aggregate of multiple small particles 200. Because each small particle 200 is angular, the raw material particle 100 has a surface morphology with angular protrusions and deep recesses between adjacent small particles 200. Furthermore, from the lower SEM image of Figure 3A and the two SEM images of Figure 3B (both magnifications: 100,000x), it can be confirmed that the surface of each small particle 200 is a smooth crystal plane. Since the raw material particles 100 have an uneven surface, the resin viscosity of the raw material powder made of the raw material particles 100 tends to be high.

[0019] On the other hand, the SEM images (magnification: 500x) in the upper part of Figure 2A and the upper part of Figure 2B show inorganic aluminum compound particles 10 according to an embodiment of the present invention, which are obtained by subjecting raw material particles 100 (see Figure 3A) of an inorganic aluminum compound to an abrasion treatment (a treatment for abrading the surface of the raw material particles 100). The abrasion treatment transforms the angular small particles 200 (see Figure 3A) of the raw material particles 100 into rounded small particles 20, and the deep recesses between the small particles 200 in the raw material particles 100 (see Figure 3A) are filled with fine abrasion debris 30. As a result, the inorganic aluminum compound particles 10 have a rounded surface morphology as a whole. Furthermore, as shown in the SEM images (magnification: 100,000x) in the lower part of Figure 2A and the lower part of Figure 2B, a large amount of abrasion debris 30 adheres to the surface of each small particle 20. Since the inorganic aluminum compound particles 10 have a surface morphology with few irregularities, the resin viscosity of the inorganic aluminum compound powder made of the inorganic aluminum compound particles 10 tends to be low.

[0020] The inorganic aluminum compound particles 10 have a pore structure formed by recesses between adjacent small particles 20 and wear powder present on the surfaces of the small particles 20. Therefore, the large pore volume of the inorganic aluminum compound powder suggests that wear has progressed and the inorganic aluminum compound particles 10 constituting the inorganic aluminum compound powder have become rounded.

[0021] Next, a description will be given of the abrasion treatment for producing inorganic aluminum compound particles as shown in FIGS. 2A and 2B from raw material particles as shown in FIG. 3A. The "abrasion treatment" in this specification is performed by stirring the raw powder under stirring conditions that abrade the angular protrusions of the raw material particles 100 shown in FIG. 3A while suppressing pulverization of the raw material particles 100 themselves (this may be referred to as "abrasion stirring"). In other words, the "abrasion treatment" in this specification refers to stirring (abrasion stirring) under significantly milder stirring conditions than the grinding conditions used in conventional methods for producing aluminum hydroxide powder. The abrasion treatment suppresses pulverization of the raw material particles 100, abrading the angular protrusions and making the particles overall rounder. The amount of abrasion that occurs in the abrasion treatment can be controlled, for example, by the abrasion time. The abrasion powder generated by the abrasion of the angular protrusions adheres to the surface of the raw material particles, and some of it gets stuck in the deep recesses of the raw material particles, resulting in inorganic aluminum compound particles 10 that are rounded overall (see FIGS. 2A and 2B).

[0022] The amount of abrasion powder generated by the abrasion treatment is an index for determining the degree of abrasion of the angular protrusions of the raw material particles 100 (FIG. 3A), that is, the degree of roundness of the inorganic aluminum compound particles 10. As described above, adhesion of wear powder to inorganic aluminum compound particles (including clogging of recesses) forms a pore structure on the particle surface, increasing the pore volume of the inorganic aluminum compound powder. The present inventors have investigated the use of the pore volume of inorganic aluminum compound powder (pore volume of a given pore radius in a nitrogen adsorption / desorption isotherm) as an index of the amount of wear powder adhered to inorganic aluminum compound particles 10, and have found that the pore volume (mesopore volume) corresponding to a pore radius of 1.4 to 94 nm (so-called mesopores) correlates with the amount of adhered wear powder. In other words, the specific mesopore volume V (cm 3 / g) (mesopore volume per 1 g of inorganic aluminum compound powder) is thought to be largely contributed by wear particles adhering to the inorganic aluminum compound particles 10.

[0023] In this specification, the "specific mesopore volume" of the inorganic aluminum compound powder refers to the pore volume measured by the measurement method described below, and does not necessarily mean that the inorganic aluminum compound particles 10 have mesopores. In an embodiment of the present invention, the value of the specific mesopore volume is considered to be related to the amount of wear powder adhering to the inorganic aluminum compound particles 10.

[0024] As a result of further investigations by the present inventors, it was confirmed that the specific mesopore volume of an inorganic aluminum compound powder is affected not only by the amount of wear debris adhering to inorganic aluminum compound particles 10 but also by the particle size of the inorganic aluminum compound powder. Therefore, in order to eliminate the effect of particle size on the specific mesopore volume, it was decided to introduce the specific mesopore volume V of the inorganic aluminum compound powder multiplied by D50 of the inorganic aluminum compound powder (V × D50: structural parameter) as an index for indirectly knowing the roundness of inorganic aluminum compound particles 10. Inorganic aluminum compound particles 10 with a large structural parameter are rounded, and inorganic aluminum compound powder containing such inorganic aluminum compound particles 10 can effectively suppress an increase in resin viscosity.

[0025] In the above formula (1), the structural parameter V × D50 is 0.11 (μm cm 3 / g) or more. By satisfying formula (1), an inorganic aluminum compound powder containing rounded inorganic aluminum compound particles as shown in Figures 2A and 2B can be obtained. The structural parameters can be controlled by changing the stirring time in the abrasion treatment (stirring the raw material powder) of the raw material particles 100 that is carried out during the production of the inorganic aluminum compound powder. If the stirring time is increased, the abrasion of the raw material particles 100 progresses, and the amount of abrasion powder generated increases, and the amount of abrasion powder adhering to the inorganic aluminum compound particles 10 also increases, resulting in an increase in the specific mesopore volume V and an increase in the structural parameters.

[0026] The structural parameter of the inorganic aluminum compound powder is 0.11 (μm cm3 / g) or more is preferable, and 0.15 (μm cm 3 / g) or more is more preferable, and 0.30 (μm cm 3 / g) or more is more preferable, and 0.80 (μm cm 3 / g) or more is particularly preferred. The upper limit of the structural parameter is not particularly limited. From the research results of the present inventors, it is preferable that the structural parameter is 3.0 to 4.0 (μm cm 3 / g), the effect of suppressing the resin viscosity is expected to reach saturation. From the viewpoint of maximizing the effect of suppressing the resin viscosity while suppressing the manufacturing cost, the structural parameter is set to 4.0 (μm cm 3 The structural parameter is preferably 3.0 (μm cm 3 / g) or less, and may be 1.1 (μm cm 3 / g) or less.

[0027] Specific mesopore volume V(cm 3 / g) is calculated as follows: As a pretreatment, the inorganic aluminum compound powder is subjected to vacuum degassing at 120°C for 8 hours. For the pretreatment, an appropriate pretreatment device (e.g., BELPREP-vacII (Microtrack-Bell)) can be used. Then, the pretreated inorganic aluminum compound powder is subjected to nitrogen adsorption / desorption isotherm measurement by the constant volume method using a measuring device (e.g., BELSORP-miniII (Microtrack-Bell)). The adsorption temperature is 77 K, and the adsorbate cross section is 0.162 nm 2 The equilibrium waiting time (the waiting time after the pressure change during adsorption / desorption reaches a predetermined value or less) is set to 500 seconds. In the BJH method, the amount of nitrogen adsorbed in mesopores corresponding to pore radii of 1.4 to 94 nm is calculated as the specific mesopore volume of the inorganic aluminum compound powder.

[0028] As described above, when producing the inorganic aluminum compound powder, the raw material particles 100 are agitated (abrasion agitation) under agitation conditions that do not (or are unlikely to) cause pulverization of the raw material particles 100, thereby carrying out an abrasion treatment. In other words, the inorganic aluminum compound powder according to this embodiment is produced without a pulverization treatment, and therefore tends to have a relatively sharp particle size distribution. For example, the particle size distribution of the inorganic aluminum compound powder may satisfy the following formula (3): (D90-D10) / D50≦3.0 (3) Here, D10, D50, and D90 are particle sizes (μm) at which the cumulative frequency from the fine particle side in the volume-based particle size distribution of the inorganic aluminum compound powder is 10 volume%, 50 volume%, and 90 volume%, respectively. (D90-D10) / D50 may be 0.5 or more and 2.5 or less, or 0.6 or more and 2.0 or less. The lower limit of (D90-D10) / D50 may be 0.7 or more.

[0029] D10, D50 and D90 are determined as follows. The inorganic aluminum compound powder is added to a 0.2% by mass aqueous solution of sodium hexametaphosphate, and ultrasonic waves at 25 W are applied for 15 seconds (120 seconds if D50 is 15 μm or less) to disperse the inorganic aluminum compound powder in the aqueous solution. The volume-based particle size distribution is measured using a laser scattering particle size distribution analyzer, and the particle sizes at which the cumulative frequency from the fine particle side is 10 vol%, 50 vol%, and 90 vol% (D10, D50, and D90, respectively) are determined. Considering the differences between instruments and the consistency with the present example, it is preferable to use a Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.) or an equivalent device as the laser scattering particle size distribution analyzer. Furthermore, when measuring the particle size distribution, it is preferable to adjust the concentration of the inorganic aluminum compound powder to a measurable concentration for the above-mentioned measuring device before measurement.

[0030] The inorganic aluminum compound powder is, for example, aluminum hydroxide powder, which has high heat dissipation properties and excellent flame retardancy, making it suitable for use in heat dissipation members.

[0031] When the inorganic aluminum compound powder is aluminum hydroxide powder, it preferably satisfies the following formula (2). 2.0≦I 002 / I 110 ≦6.0 (2) where: I 110 and I 002 are the peak diffraction intensities of the (110) and (002) planes of aluminum hydroxide in the XRD pattern, respectively.

[0032] In addition, the middle part of equation (2) is "I 002 / I 110 " indicates the intensity ratio of the peak diffraction intensity of the (002) plane to the peak diffraction intensity of the (110) plane of aluminum hydroxide. In this specification, this intensity ratio I 002 / I 110 is sometimes referred to as the "XRD index." The XRD index is an index showing the degree to which cleavage planes are exposed on the surface of the aluminum hydroxide particles that make up the aluminum hydroxide powder, that is, an index showing the degree of pulverization during the production of the aluminum hydroxide powder.

[0033] Formula (2) defines that the XRD index is preferably 2.0 or more and 6.0 or less. An XRD index of 6.0 or less suggests that the generation of plate-shaped particles during milling is suppressed in the aluminum hydroxide particles that make up the aluminum hydroxide powder. Therefore, aluminum hydroxide particles with an XRD index of 6.0 or less can further reduce the viscosity of resins. When the XRD index is 2.0 or more, the manufacturing conditions can be relaxed, and productivity can be particularly improved.

[0034] The XRD index is preferably 2.0 or more and 6.0 or less, more preferably 2.5 or more and 5.5 or less, and particularly preferably 2.8 or more and 4.0 or less. The XRD index can be affected by the orientation of the crystal grains (for example, the shape of the particles), but it is believed that the contribution of cleavage, rather than just the orientation of the crystal grains, is significant for an XRD index of more than 6.0.

[0035] The XRD indices are determined as follows. The aluminum hydroxide powder is lightly packed into a 1 mm deep resin measurement cell to avoid compaction, and the surface is smoothed. Then, using a powder X-ray diffractometer (e.g., Bruker D8 Advance), the XRD pattern is measured at a step width of 0.02 deg, a scan speed of 2.5 s / step, an accelerating voltage of 40 kV, and an accelerating current of 40 mA. A Cu-Kα X-ray source is used. In the obtained XRD pattern, the peak appearing in the 2θ range of 17.50 to 19.00° is taken as the peak for the (002) plane, and the peak appearing in the 2θ range of 20.00 to 20.42° is taken as the peak for the (110) plane. The peak diffraction intensity I of the (110) plane peak is calculated. 110 Peak diffraction intensity of the (002) peak versus (peak height) I 002 The intensity ratio (XRD index) (peak height) is calculated.

[0036] The inorganic aluminum compound powder preferably has a D50 of 5 μm or more and 130 μm or less. When the D50 is 130 μm or less, the inorganic aluminum compound powder can be produced relatively easily, and when the D50 is 5 μm or more, the filling rate of the inorganic aluminum compound powder relative to the resin material can be further improved. The inorganic aluminum compound powder preferably has a D50 of 10 μm or more and 120 μm or less, and more preferably 55 μm or more and 84 μm or less.

[0037] Inorganic aluminum compound powder has a BET specific surface area of ​​0.5m 2 / g or more, and the pore volume is sufficiently formed by the wear powder, so that an increase in the resin viscosity can be effectively suppressed. Although the upper limit of the BET specific surface area is not particularly limited, it is generally 5.0 m 2 It is estimated that the effect of suppressing resin viscosity will saturate if the viscosity exceeds 5.0 m / g. 2 / g, which can maximize the effect of suppressing the resin viscosity while suppressing the production cost. The BET specific surface area of ​​inorganic aluminum compound powder is 0.5m 2 / g or more 5.0m 2 / g or less is more preferable, and 2.0m 2 / g or more 4.0m 2 It is particularly preferable that the saturation coefficient is 1 / g or less.

[0038] 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.

[0039] The inorganic aluminum compound powder according to the 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 product. Examples of resins that can be used to form resin molded bodies include thermosetting resins such as unsaturated polyester resins, epoxy resins, phenolic resins, and polyurethane resins; and thermoplastic resins such as polyethylene, polypropylene, copolymers of ethylene and propylene, and copolymers of ethylene and / or propylene with other α-olefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 4-methyl-1-pentene, and 1-decene; styrene (co)polymers, methyl methacrylate (co)polymers, polyamides, polycarbonates, ethylene-vinyl acetate copolymers, polyacetals, acrylonitrile-butadiene-styrene copolymers, polyphenylene oxide, polyethersulfone, polyarylates, polyetheretherketones, and polymethylpentene. The inorganic aluminum compound powder according to the present invention is not limited to the above resins, and can also be used as a filler for other synthetic resins, natural resins, paper, and the like.

[0040] <2. Method for producing inorganic aluminum compound powder> The method for producing an inorganic aluminum compound powder according to an embodiment of the present invention includes: (a) a step of preparing a raw aluminum hydroxide powder having a D50 of 50 to 200 μm (raw powder preparation step), and (b) a step of agitating the raw aluminum hydroxide powder (attrition agitation) to abrade the surfaces of the raw aluminum hydroxide particles (attrition treatment step of raw particle). Each step will be described in detail below using aluminum hydroxide powder as an example.

[0041] [(a) Raw material powder preparation process] An aluminum hydroxide powder (hereinafter also referred to as "raw aluminum hydroxide powder" or "raw powder") is prepared as a raw material. The raw aluminum hydroxide powder preferably has a D50 of 50 to 200 μm. This makes it easier to obtain aluminum hydroxide powder with the desired structural parameters (V×D50).

[0042] The crystal structure of the raw material aluminum hydroxide powder may be, for example, gibbsite type or bayerite type, with the gibbsite type being preferred.

[0043] The raw aluminum hydroxide powder (raw powder) can be produced by adding seed crystals to a supersaturated sodium aluminate solution, precipitating aluminum hydroxide with stirring, filtering and washing the resulting aluminum hydroxide, and then subjecting it to post-treatments such as drying, crushing, and pulverization. This produces a raw aluminum hydroxide powder having the above particle size. Commercially available aluminum hydroxide powders may also be used as long as they satisfy the above particle size requirements.

[0044] [(b) Raw material particle abrasion treatment process] By stirring raw aluminum hydroxide powder (raw powder) under an appropriate stress, the raw aluminum hydroxide particles (hereinafter referred to as "raw particles") contained in the raw powder are rubbed against each other. This causes the angular protrusions on the surface of the raw particles to be worn (or ground) to generate abrasion powder, resulting in the production of rounded aluminum hydroxide particles (see Figure 2). In the methods for producing aluminum hydroxide powder disclosed in Patent Documents 1 and 2, the raw material powder is mixed under high pressure to pulverize the raw material particles. In contrast, in the embodiment of the present invention, the pressure applied to the raw material powder during stirring is intentionally kept low to prevent the raw material particles from being pulverized during stirring. Stirring is performed under low pressure (abrasion stirring), which slows the progress of abrasion. Therefore, to achieve sufficient abrasion, the stirring time must be relatively long.

[0045] Suitable devices for abrasion treatment (abrasion mixing) to wear down the surfaces of raw material particles include planetary mixers (e.g., the Awatori Rentaro ARV-310, a rotation-revolution mixer manufactured by Thinky Corporation) and twin-shaft blade mixers (e.g., the Labo Plastomill R100, a batch-type closed-type roller mixer manufactured by Toyo Seiki Seisakusho). These devices are typically used for mixing resins, but the inventors' investigations have shown that they are also suitable for wearing down the surfaces of raw material particles without pulverizing them, because they can agitate while applying an appropriate stress to the raw material powder. The conditions suitable for abrasive agitation of raw material particles using each device are described below.

[0046] (b-1) Planetary mixer The abrasion agitation using a planetary agitator is preferably controlled so as to satisfy the following conditions (1-i) to (1-iv).

[0047] (1-i) The revolution speed is set to 200 to 2000 rpm (for example, 2000 rpm), and the raw material powder is compacted by centrifugal force. Compaction is preferably carried out so that the packing ratio, which is the actual volume of the raw material powder relative to the volume (bulk) of the raw material powder when it is fed into the mixer during processing, is 35 to 85% by volume. If the packing ratio is less than 35% by volume, wear is difficult to progress, and if it exceeds 85% by volume, mixing is difficult.

[0048] (1-ii) The rotation speed is set to 100 to 1000 rpm (for example, 1000 rpm), and the raw material powder is stirred at high speed.

[0049] (1-iii) Fluidize the raw material powder in the mixer. It is desirable to fluidize the particles at 0.01 to 100 m / sec. If the fluidization speed is too low, cracking (cleavage) of the raw material particles may occur and the efficiency of the abrasion treatment may decrease. If the fluidization speed is too high, it becomes difficult to carry out. The fluidization speed can be controlled by the rotation speed.

[0050] (1-iv) The moisture content of the raw powder during abrasion stirring is controlled to be appropriate. It is desirable that the raw powder contains 0 to 30 mass% of water as a lubricating component relative to 100 mass% of the raw powder (including water) (i.e., a moisture content of 0 to 30 mass%). If the moisture content is too high, abrasion may be suppressed, reducing the efficiency of the abrasion treatment.

[0051] (b-2) Twin-screw blade kneader The abrasion stirring using the twin-screw blade kneader is preferably controlled so as to satisfy the following conditions (2-i) to (2-iii).

[0052] (2-i) It is preferable to fill the mixer with raw material powder so that the packing ratio of the dry raw material powder in the mixer is 35 to 85% by volume (for example, 58% by volume), which allows the raw material particles to rub against each other to an appropriate degree. If the packing ratio is less than 35% by volume, wear does not progress easily, and if it exceeds 85% by volume, mixing is difficult.

[0053] (2-ii) The raw material powder is fluidized in the kneader by rotating the blades at a speed of 5 to 500 rpm (e.g., 40 rpm). Fluidization at 0.01 to 100 m / sec is desirable. If the fluidization speed is too low, cracking (cleavage) of the raw material particles may occur and processing efficiency may decrease. If the fluidization speed is too high, it becomes difficult to perform abrasive stirring.

[0054] (2-iii) The moisture content of the raw powder during abrasion stirring is controlled to be appropriate. It is desirable that the raw powder contains 0 to 30 mass% of water as a lubricating component relative to 100 mass% of the raw powder (including water) (i.e., a moisture content of 0 to 30 mass%). If the moisture content is too high, abrasion may be suppressed, reducing the efficiency of the abrasion treatment.

[0055] 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) within the scope in which the object of the present invention is achieved. [Example]

[0056] 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-described and below-described aims, and all such modifications are within the technical scope of the embodiments of the present invention.

[0057] Example 1 Seed crystals were added to a supersaturated sodium aluminate solution, and aluminum hydroxide was precipitated with stirring. The resulting aluminum hydroxide was filtered, washed, and dried to obtain raw aluminum hydroxide powder (D50: 85 μm). 15 parts by mass of water was added to 100 parts by mass of the obtained raw aluminum hydroxide powder, and the mixture was stirred for 1 minute using a centrifugal mixer (Thinky Corporation, Awatori Rentaro ARV-310) at a centrifugal rotation of 1000 rpm and a centrifugal revolution of 2000 rpm, thereby causing the particles to pack closely together while undergoing high-speed abrasion agitation (locally at a maximum of approximately 5 m / sec) (abrasion treatment). The powder was then disintegrated using a medicine spoon. This abrasion agitation and disintegration process was repeated 10 times. The obtained powder was dried at 110°C for at least 2 hours, yielding the aluminum hydroxide powder of Example 1.

[0058] Example 2 Commercially available aluminum hydroxide powder (Sumitomo Chemical, CW-308 (D50=11 μm)) was used as the raw material aluminum hydroxide powder. 15 parts by mass of water was added to 100 parts by mass of raw aluminum hydroxide powder, and the mixture was placed in a disposable cup. This mixture was stirred for 1 minute using a centrifugal mixer (Thinky Corporation, Awatori Rentaro ARV-310) at a centrifugal rotation of 1000 rpm and a centrifugal revolution of 2000 rpm, thereby causing the particles to pack densely together while undergoing high-speed abrasion (locally at a maximum of approximately 5 m / sec) (abrasion treatment). The powder was then disintegrated using a medicine spoon. This abrasion and disintegration process was repeated five times. The resulting powder was dried at 110°C for at least 2 hours, yielding the aluminum hydroxide powder of Example 2.

[0059] Example 3 Seed crystals were added to a supersaturated sodium aluminate solution, and aluminum hydroxide was precipitated with stirring. The resulting aluminum hydroxide was filtered, washed, and dried to obtain raw aluminum hydroxide powder (D50: 73 μm). To 100 parts by mass of the obtained raw aluminum hydroxide powder, 15 parts by mass of water was added, and the wet powder was charged into a closed sample chamber using a batch-type closed roller mixer (Toyo Seiki Seisakusho, Labo Plastomill, R100) so that the volume filling rate was 58% by volume in terms of the dry raw powder, and the mixture was agitated by abrasion with two blades at a rotation speed of 40 rpm for 30 minutes (abrasion treatment). The obtained powder was dried at 110°C for 2 hours or more to obtain the aluminum hydroxide powder of Example 3.

[0060] (Comparative Example 1) The raw aluminum hydroxide powder (D50: 85 μm) prepared in Example 1 was used as the aluminum hydroxide powder of Comparative Example 1.

[0061] (Comparative Example 2) A commercially available aluminum hydroxide powder (Sumitomo Chemical Co., Ltd., CW-308 (D50=11 μm)) was used as the aluminum hydroxide powder of Comparative Example 2.

[0062] (Comparative Example 3) A commercially available aluminum hydroxide powder (Sumitomo Chemical Co., Ltd., C-305 (D50=5.3 μm)) was used as the aluminum hydroxide powder of Comparative Example 3.

[0063] The aluminum hydroxide powders of Examples 1 to 3 and Comparative Examples 1 to 3 were measured for the specific mesopore volume V, D10, D50, D90, and XRD index (I 002 / I 110 ), BET specific surface area, and resin viscosity were determined. In addition, the structural parameter (V × D50) and particle size distribution (D90 - D10) / D50 were calculated from the measurement results. The measurement and calculation results are shown in Table 1.

[0064] [Specific mesopore volume V] As a pretreatment, aluminum hydroxide powder was subjected to vacuum degassing at 120°C for 8 hours. A BELPREP-vac II (Microtrack-Bell) was used for the pretreatment. The nitrogen adsorption / desorption isotherm of the pretreated aluminum hydroxide powder was then measured by the constant volume method using a BELSORP-mini II (Microtrack-Bell). The adsorption temperature was 77 K, and the adsorbate cross-sectional area was 0.162 nm. 2 The equilibrium waiting time was set to 500 seconds. In the BJH method, the amount of nitrogen adsorbed in mesopores corresponding to pore radii of 1.4 to 94 nm was calculated as the specific mesopore volume.

[0065] [D10, D50, D90] Aluminum hydroxide powder was added to a 0.2% by mass aqueous solution of sodium hexametaphosphate and irradiated with 25 W ultrasonic waves for 15 seconds (120 seconds if D50 was 15 μm or less) to disperse the aluminum hydroxide powder in the aqueous solution. The volumetric particle size distribution of the dispersion was measured using a laser scattering particle size distribution analyzer, and the particle sizes at which the cumulative frequency from the finest particles was 10%, 50%, and 90% by volume (D10, D50, and D90, respectively) were determined. The laser scattering particle size distribution analyzer used was a Microtrac MT-3300EXII (manufactured by Nikkiso Co., Ltd.). The concentration of the aluminum hydroxide powder was adjusted appropriately to a concentration measurable by the analyzer.

[0066] [XRD index(I 002 / I 110 )] The aluminum hydroxide powder was lightly packed into a 1 mm deep resin measurement cell to avoid compaction, and the surface was smoothed. Then, an XRD pattern was measured using a powder X-ray diffractometer (Bruker, D8 Advance) with a step width of 0.02 deg, a scan speed of 2.5 s / step, an accelerating voltage of 40 kV, and an accelerating current of 40 mA. Cu-Kα was used as the X-ray source. In the obtained XRD pattern, the peak appearing in the range of 2θ = 17.50 to 19.00° was defined as the peak of the (002) plane, and the peak appearing in the range of 2θ = 20.00 to 20.42° was defined as the peak of the (110) plane. The peak diffraction intensity I of the (110) plane peak was calculated. 110 Peak diffraction intensity of the (002) peak versus (peak height) I 002 The intensity ratio (peak height) was taken as the XRD index.

[0067] [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) according to the method specified in JIS-Z-8830:2013.

[0068] [Resin viscosity] 75 parts by mass of aluminum hydroxide powder and 25 parts by mass of the polyol resin mixture were mixed for 1 minute at 2000 rpm using a planetary centrifugal mixer (Thinky Corporation, Awatori Rentaro ARV-310) to obtain a compound. A dynamic viscoelasticity measuring device (Rheosol-G3000) was equipped with parallel plates of 30 mm diameter, and the compound was set on the plates. After leaving the mixture at rest for 10 minutes under conditions of a 1 mm gap between the parallel plates and a temperature of 50°C, the mixture was subjected to shear at a rate of 40 s. -1 The resin viscosity was measured at this temperature.

[0069] The structural parameters shown in Table 2 are plotted on the horizontal axis and the XRD indexes on the vertical axis, and the results of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in FIG.

[0070] [SEM image] SEM images were taken of the aluminum hydroxide powders of the examples and comparative examples. Figures 2A to 3B show the SEM images. The measurement conditions for the SEM images were as follows: The powder was sprinkled with a spatula onto conductive carbon tape fixed to a cylindrical sample stage to prepare a sample for observation. The particle appearance was observed as a backscattered electron image using a tabletop microscope, Miniscope (registered trademark) TM4000 (Hitachi High-Technologies), at an accelerating voltage of 15 kV. Furthermore, the microstructure of the worn state was observed as a secondary electron image using a field-emission scanning electron microscope, S-5500 (Hitachi High-Technologies), at an accelerating voltage of 1 kV. The magnification was 500x or 100,000x.

[0071] [Table 1]

[0072] The results in Table 1 lead to the following conclusions. All of Examples 1 to 3 are examples that satisfy all of the requirements defined in the embodiments of the present invention, and the increase in resin viscosity was sufficiently suppressed compared to the comparative examples.

[0073] On the other hand, Comparative Examples 1 to 3 are examples in which the structural parameters are outside the ranges defined in the embodiments of the present invention, and the increase in resin viscosity could not be sufficiently suppressed compared to the Comparative Examples.

[0074] From the SEM image (500x) of Comparative Example 1 shown in FIG. 3A, it was confirmed that raw aluminum hydroxide particles 100 that had not been subjected to abrasive stirring had angular protrusions and deep recesses. In contrast, the SEM images (500x magnification) of Examples 1 and 3 shown in Figures 2A and 2B confirm that the abrasion treatment (abrasion stirring) rounded off any angular convex portions and filled in any deep concave portions (with abrasion debris), resulting in generally rounded aluminum hydroxide particles 10. Furthermore, the SEM images (100,000x magnification) of Examples 1 and 3 shown in Figures 2A and 2B confirm that fine powder (abrasion debris 30) adhered to the surfaces of aluminum hydroxide particles 10.

Claims

1. An inorganic aluminum compound powder that satisfies the following formula (1): V × D50 ≧ 0.11 (1) where: V is the specific mesopore volume (cm) of the inorganic aluminum compound powder. ３ / g), D50 is the particle size (μm) at which the cumulative frequency from the fine particle side in the volume-based particle size distribution of the inorganic aluminum compound powder is 50% by volume.

2. 2. The inorganic aluminum compound powder according to claim 1, which is an aluminum hydroxide powder.

3. The inorganic aluminum compound powder according to claim 2, which satisfies the following formula (2): 2.0≦I ００２ / I １１０ ≦6.0 (2) where: I １１０ and I ００２ are the peak diffraction intensities of the (110) and (002) planes of aluminum hydroxide in the XRD pattern, respectively.

4. D50 is 5 μm or more and 130 μm or less, BET specific surface area is 0.5m ２ The inorganic aluminum compound powder according to any one of claims 1 to 3, wherein the SiO2 content is 1 / g or more.

Images