Boron nitride aggregated particles, method for producing boron nitride aggregated particles, resin composition containing the boron nitride aggregated particles, and molded article

Abstract

To provide boron nitride aggregated particles which are suitable as a thermally conductive filler for a heat-radiation sheet of a power semiconductor device, and are excellent in isotropy of thermal conductivity, disintegration resistance and kneading property with resin.SOLUTION: Boron nitride aggregated particles (hereinafter referred to as "BN aggregated particles") are formed by aggregating boron nitride primary particles (hereinafter referred to as "BN primary particles"). A peak area intensity ratio ((100) / (004)) of a (100) plane and a (004) plane of the BN primary particles is 0.25 or more which is obtained by measuring a pellet-like sample obtained by molding at a molding pressure of 0.85 ton / cm2 or more and 2.54 ton / cm2 or less with a powder tablet molding machine of 10 mmφ, with powder X-ray diffraction. An average crystallite size of the BN primary particles is 375 Å or more which is determined from the peak of a (002) plane of the BN primary particles that fills a glass sample plate with a depth of 0.2 mm with the BN aggregated particles so that its surface becomes smooth and is obtained by measuring the BN aggregated particles with the powder X-ray diffraction.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to boron nitride aggregated particles (hereinafter referred to as "BN aggregated particles") and a method for producing the particles. More specifically, the present invention relates to BN aggregated particles formed by aggregation of boron nitride primary particles (hereinafter referred to as "BN primary particles") and a method for producing the same. The present invention also relates to a resin composition containing the BN aggregated particles and a molded article formed by molding the resin composition containing the BN aggregated particles.

Background Art

[0002] Boron nitride (hereinafter referred to as "BN") is an insulating ceramic, and various crystal forms such as c-BN having a diamond structure, h-BN having a graphite structure, α-BN having a turbostratic structure, and β-BN are known. Among these, h-BN has the same layered structure as graphite, and is relatively easy to synthesize and has excellent thermal conductivity, solid lubricity, chemical stability, and heat resistance. Therefore, it is widely used in the field of electric and electronic materials.

[0003] In recent years, particularly in the field of electric and electronics, heat generation associated with the high density of integrated circuits has become a major problem, and how to dissipate heat has become an urgent issue. Taking advantage of the characteristic that h-BN has high thermal conductivity despite being insulating, it has attracted attention as a thermal conductive filler for such heat dissipation members. However, h-BN has a plate-like particle shape, and although it exhibits high thermal conductivity in the plate surface direction (within the ab plane or within the (002) plane) (usually about 400 W / mK as the thermal conductivity), it has low thermal conductivity in the plate thickness direction (C-axis direction) (usually about 2 to 3 W / mK as the thermal conductivity). Therefore, when this is blended with a resin to form a resin composition containing BN particles, for example, when a plate-like molded article is molded, the plate-like h-BN is oriented in the plate surface direction of the molded article, which is the flow direction of the resin composition containing BN particles during molding. The resulting molded article has excellent thermal conductivity in the plate surface direction but only low thermal conductivity in the thickness direction.

[0004] Therefore, in order to improve the anisotropy of the thermal conductivity of h-BN, even when a molded body is formed, aggregated particles of h-BN having a shape other than a flaky plate shape with less orientation as described above have been studied. Examples of such aggregated h-BN particles include h-BN aggregated particles granulated by spray drying or the like, and h-BN aggregated particles produced by sintering h-BN and pulverizing the sintered body (Patent Documents 1 and 2). In addition, aggregated h-BN particles produced from a mixture of boric acid and melamine, which are fluffy aggregated h-BN particles in which h-BN primary particles are aggregated without orientation, have also been proposed (Patent Document 3).

[0005] In other words, in conventional aggregated h-BN particles, it has been studied to reduce the contact resistance between aggregated particles by producing large aggregated particles. In addition, in order to achieve high thermal conductivity by reducing the grain boundaries between h-BN primary particles constituting the aggregated h-BN particles, h-BN primary particles having a relatively large particle diameter of about several μm to several hundred μm and high crystallinity have been used (Patent Documents 1, 2, and 3).

[0006] As an application of such conventional aggregated BN particles, it is known to be used for a heat dissipation sheet required in a power semiconductor device or the like. However, in order to reduce the contact resistance between aggregated BN particles, molding under a certain pressure is required. As a result, the aggregated BN particles collapse due to the pressure, and the h-BN primary particles are oriented in the molding surface direction. As a result, the thermal conductivity in the direction perpendicular to the molding surface is low, and the current situation is that it has not reached the practical level. That is, there is a demand for aggregated BN particles that can impart high thermal conductivity in the direction perpendicular to the heat dissipation sheet even under a certain pressure, and further development of aggregated particles having high thermal conductivity of the aggregated BN particles themselves is desired.

Prior Art Documents

Patent Documents

Patent Document 1

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to the studies of the present inventors, it has been found that in conventional BN agglomerated particles, the interface between h-BN primary particles constituting the BN agglomerated particles and the low crystallinity of the h-BN primary particles are one of the causes for reducing the thermal conductivity of the BN agglomerated particles. That is, these causes are considered to be because phonons, which are the carriers of thermal conduction, are scattered at the h-BN primary particle interfaces and the grain boundaries in the h-BN primary particles.

[0009] Also, when the resin is filled with conventional BN agglomerated particles, although the contact resistance between the agglomerated particles due to increasing the size of the BN agglomerated particles can be reduced to some extent, it has been found that the orientation of the h-BN primary particles constituting the BN agglomerated particles increases the contact resistance between the BN agglomerated particles and causes a decrease in thermal conductivity. That is, in order to improve the thermal conductivity as a molded body, it is considered effective to control the orientation of the h-BN primary particles constituting the BN agglomerated particles, reduce the contact resistance between the BN agglomerated particles, increase the crystallinity of the h-BN primary particles constituting the BN agglomerated particles, and further reduce the grain boundaries in the h-BN primary particles constituting the BN agglomerated particles.

[0010] An object of the present invention is to solve the above-mentioned conventional problems, produce BN agglomerated particles in which the h-BN primary particles constituting the BN agglomerated particles have high thermal conductivity and the contact resistance between the BN agglomerated particles is also reduced, and provide BN agglomerated particles having excellent applicability to various molded bodies and a method for producing the same. Another object of the present invention is to provide a BN agglomerated particle-containing resin composition containing the BN agglomerated particles and a resin, and a molded body formed by molding the BN agglomerated particle-containing resin composition.

Means for Solving the Problems

[0011] As a result of intensive studies, the present inventors have found that by setting the viscosity of the raw material slurry when producing BN agglomerated particles within a specific range, the average crystallite size in the h-BN primary particles constituting the BN agglomerated particles increases. An increase in the average crystallite size reduces the grain boundaries between the crystallites in the h-BN primary particles, and as a result, the inventors have succeeded in enhancing the thermal conductivity of the BN agglomerated particles. Furthermore, surprisingly, the BN agglomerated particles thus produced have a specific crystal plane of the h-BN primary particles constituting the BN agglomerated particles oriented, and when a molded body is formed using the BN agglomerated particles, it has been found that a molded body with higher thermal conductivity than conventional BN agglomerated particles can be produced, leading to the completion of the present invention.

[0012] That is, the gist of the present invention is a boron nitride agglomerated particle (hereinafter referred to as "BN agglomerated particle") formed by aggregation of boron nitride primary particles (hereinafter referred to as "h-BN primary particles"), wherein the peak area intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of the h-BN primary particles obtained by powder X-ray diffraction measurement of a pellet-shaped sample obtained by molding at a molding pressure of 0.85 ton / cm 2 or more and 2.54 ton / cm 2 or less is 0.25 or more, and the BN agglomerated particles are filled in a glass sample plate with a depth of 0.2 mm so that the surface becomes smooth, and the average crystallite size of the h-BN primary particles determined from the (002) plane peak of the h-BN primary particles obtained by powder X-ray diffraction measurement is 375 Å or more, characterized by B N agglomerated particles. Also, the average particle size D 50 (μm) of the BN agglomerated particles is preferably 26 μm or more, the specific surface area of the BN agglomerated particles is preferably 8 m 2 / g or less, the BN agglomerated particles are preferably spherical, the BN agglomerated particles preferably have a card house structure, and the average particle size of the h-BN primary particles is preferably 1.1 μm or more.

[0013] Furthermore, still another gist of the present invention resides in a BN agglomerated particle composition which is a mixture of the above BN agglomerated particles and other fillers, still another gist resides in a BN agglomerated particle-containing resin composition containing a resin and the above BN agglomerated particles, and still another gist resides in a molded article containing the above BN agglomerated particles.

[0014] Furthermore, still another gist of the present invention resides in a method for producing BN agglomerated particles, which includes a step of preparing a slurry of raw material boron nitride powder (hereinafter referred to as "BN slurry"), and a step of heat-treating the slurry, wherein the viscosity of the BN slurry is 200 mPa·s or more and 5000 mPa·s or less, and the heat treatment is performed at 1800°C to 2300°C. Also, the oxygen concentration in the raw material boron nitride powder is preferably 1% by mass or more and 10% by mass or less.

Advantages of the Invention

[0015] The BN agglomerated particles of the present invention have an average crystallite size of the h-BN primary particles of 375 Å or more determined from the (002) plane peak of the h-BN primary particles in the powder X-ray diffraction measurement of the (100) plane and (004) plane of the h-BN primary particles constituting the BN agglomerated particles obtained by powder X-ray diffraction measurement. Therefore, phonon scattering occurring at the grain boundaries in the h-BN primary particles constituting the BN agglomerated particles can be reduced, and as a result, high thermal conductivity is exhibited. Furthermore, since the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles is 0.25 or more even when molded in a specific pressure range, the molded article obtained by molding the resin composition containing the BN agglomerated particles of the present invention maintains the orientation of specific crystal planes of the h-BN primary particles constituting the BN agglomerated particles even after molding. Therefore, it exhibits high thermal conductivity in the direction perpendicular to the molding surface (the molded article thickness direction), and is very useful for a heat dissipation sheet required for power semiconductor devices and the like.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

[0017] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments and can be variously modified and implemented within the scope of the gist. [BN Agglomerated Particles] The BN agglomerated particles of the present invention are formed by aggregation of h-BN primary particles and may contain components other than the above h-BN primary particles as long as the effects of the present invention are not impaired. Examples of components other than the h-BN primary particles include components derived from binders, surfactants, and solvents that may be added to the slurry, as described in the [Method for Producing BN Agglomerated Particles] described later.

[0018] The form of the BN agglomerated particles of the present invention is not particularly limited, but preferably has a spherical form as shown in FIG. 1, and the form of the BN agglomerated particles can be confirmed by SEM. Here, "spherical" means that the aspect ratio (ratio of the major axis to the minor axis) is 1 or more and 2 or less, preferably 1 or more and 1.5 or less. The aspect ratio of the BN agglomerated particles of the present invention is determined by arbitrarily selecting 200 or more particles from the image photographed by SEM, obtaining the ratio of the major axis to the minor axis of each particle, and calculating the average value.

[0019] In addition, the BN agglomerated particles preferably have a sea urchin-like morphology in which the crystals of the h-BN primary particles grow radially from the center side to the surface side on the surface of the BN agglomerated particles, or a sea urchin-like spherical morphology in which the h-BN primary particles are small plates and are sintered and agglomerated. Further, the BN agglomerated particles preferably have a card house structure. The card house structure is described, for example, in Ceramics 43 No.2 (published by the Ceramic Society of Japan in 2008), and is a structure in which plate-like particles are stacked complexly without orientation. More specifically, the BN agglomerated particles having a card house structure are an aggregate of h-BN primary particles and have a structure in which the planar part and the end face part of the h-BN primary particles are in contact (see Fig. 3), and are preferably spherical. Also, the card house structure is preferably the same structure inside the particles. The agglomeration morphology and internal structure of these BN agglomerated particles can be confirmed by a scanning electron microscope (SEM).

[0020] In addition, when the BN agglomerated particles according to the present invention are represented by physical properties, the peak area intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of the h-BN primary particles obtained by powder X-ray diffraction measurement of a pellet-like sample obtained by molding at a molding pressure of 2.54 ton / cm 2 or less and 0.85 ton / cm 2 or more is 0.25 or more, and the average crystallite size of the h-BN primary particles determined from the peak of the (002) plane of the h-BN primary particles is 375 Å or more.

[0021] In the BN agglomerated particles of the present invention, the average crystallite diameter of the h-BN primary particles constituting them is one of the important requirements in the application as a high thermal conductivity filler. By increasing the average crystallite diameter of the h-BN primary particles constituting the BN agglomerated particles of the present invention, that is, making it 375 Å or more, the grain boundaries in the h-BN primary particles are reduced, and the thermal conductivity is excellent. Further, when molded at a pressure above a specific pressure, the area intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of the h-BN primary particles is 0.25 or more. Even when a composition containing the resin and the BN agglomerated particles of the present invention is molded under a specific pressure to produce a molded body, the orientation of a specific crystal plane of the h-BN primary particles is maintained, and there is an effect of exhibiting high thermal conductivity in the direction perpendicular to the molding pressure (the molded body thickness direction).

[0022] (Properties of BN Agglomerated Particles) ·Size of h-BN Primary Particles The major axis of the h-BN primary particles constituting the BN agglomerated particles is usually 0.5 μm or more, preferably 0.6 μm or more, more preferably 0.8 μm or more, still more preferably 1.0 μm or more, and particularly preferably 1.1 μm or more. Also, it is usually 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. Incidentally, the major axis is a value obtained by magnifying one BN agglomerated particle obtained by SEM measurement and averaging the maximum length of the h-BN primary particles observable on the image for the h-BN primary particles constituting one BN agglomerated particle.

[0023] ·Crystal Structure of h-BN Primary Particles Constituting BN Agglomerated Particles The crystal structure of the h-BN primary particles is not particularly limited, but those containing hexagonal h-BN as the main component are preferred in terms of ease of synthesis and thermal conductivity. Also, when inorganic components other than BN are included as a binder, they crystallize during the heat treatment process, but it is sufficient that BN is included as the main component. The crystal structure of the h-BN primary particles can be confirmed by powder X-ray diffraction measurement.

[0024] ·The average crystallite size of h-BN primary particles: The h-BN primary particles obtained by subjecting BN agglomerated particles to powder X-ray diffraction measurement -The average crystallite size of h-BN primary particles determined from the (002) plane peak of h-BN primary particles is not particularly limited, but it is preferably large from the viewpoint of thermal conductivity. For example, it is usually 300 Å or more, preferably 320 Å or more, more preferably 375 Å or more, still more preferably 380 Å or more, even more preferably 390 Å or more, particularly preferably 400 Å or more, and usually 5000 Å or less, preferably 2000 Å or less, more preferably 1000 Å or less. If the above average crystallite size is too large, the h-BN primary particles grow too much, so that the gaps in the BN agglomerated particles increase, the moldability when forming a molded body deteriorates, and the thermal conductivity tends not to improve due to the increase in gaps. If the above average crystallite size is too small, the grain boundaries in the h-BN primary particles increase, so that phonon scattering occurs at the crystal grain boundaries, and the thermal conductivity tends to be low.

[0025] Incidentally, the powder X-ray diffraction measurement is carried out by filling BN agglomerated particles in a glass sample plate with a depth of 0.2 mm so that the surface is smooth. Here, the "average crystallite size" is the crystallite size determined by the Scherrer equation from the (002) plane peak of h-BN primary particles obtained by powder X-ray diffraction measurement, as described in the examples below.

[0026] ·Peak area intensity ratio of h-BN primary particles BN agglomerated particles are formed into a powder tablet with a 10 mm φ tablet press at 0.85 ton / cm 2 or more and 2.54 ton / cm 2The peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles constituting the BN agglomerated particles in the pellet-shaped sample obtained by molding at the following molding pressure is usually 0.25 or more, preferably 0.30 or more, more preferably 0.35 or more, still more preferably 0.40 or more, and usually 2.0 or less, preferably 1.5 or less, still more preferably 1.2 or less. If it is too large, the contact resistance between the BN agglomerated particles tends to increase when formed into a molded body, and if it is too small, the BN agglomerated particles tend to collapse and the thermal conductivity in the thickness direction does not improve.

[0027] Generally, the optimal press pressure conditions in a heat dissipation sheet or the like vary depending on the type of the heat dissipation sheet. The BN agglomerated particles dispersed in the resin matrix are exposed to pressure conditions according to the application, but usually, the ab plane of the BN particles tends to be oriented in a direction perpendicular to the pressure direction. Even when using BN agglomerated particles, particle deformation occurs with respect to the molding pressure, and as a result, the ab plane tends to be oriented in a direction perpendicular to the pressure direction. For example, a resin high heat dissipation substrate is considered to be molded at a relatively high pressure of 0.85 ton / cm 2 or more and 2.54 ton / cm 2 or less for reducing voids inside the resin substrate and achieving complete contact between the dispersed BN agglomerated particles. Therefore, BN agglomerated particles with little change in the orientation of h-BN primary particles are necessary for improving the thermal conductivity even within the above pressure range.

[0028] In the present invention, since the BN agglomerated particles satisfying the physical properties defined in this specification, preferably the h-BN primary particles constituting the BN agglomerated particles have a card house structure, that is, a mutual reinforcement structure in which the h-BN primary particles contact each other at the primary particle plane part and the end face part, it is possible to suppress the deformation of the BN agglomerated particles in a wide molding pressure range. Although the optimal pressure range varies depending on the application, in order to achieve high thermal conductivity in the thickness direction of the molded body, it is preferable to achieve a state in which at least a certain degree of orientation of the h-BN primary particles is maintained in the range of 0.85 ton / cm 2 or more and 2.54 ton / cm 2 or less.

[0029] Orientation of h-BN primary particles above a certain level is expressed, for example, by the peak area intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of h-BN primary particles, which represents how little the ab plane is oriented in the direction perpendicular to the pressure direction, i.e., the (004) plane. Therefore, the greater the above-mentioned peak area intensity ratio, the less deformation of BN agglomerated particles due to the molding pressure. To achieve high thermal conductivity, it is considered necessary that at least the peak area intensity ratio is 0.25 or more. The lower and upper limits of the peak area intensity ratio are as described above. Regarding the lower limit and upper limit of the peak area intensity ratio, it is as described above. Incidentally, the peak area intensity ratio in the range of 0.85 ton / cm 2 or more and 2.54 ton / cm 2 If it satisfies a predetermined value at even one point within the above pressure range, there is no problem, and it is not necessary to achieve it throughout the pressure range of the present invention. Also, preferably, it satisfies a predetermined value at three points of 0.85 ton / cm 2 , 1.69 ton / cm 2 , and 2.54 ton / cm 2 .

[0030] The above-mentioned peak area intensity ratio is measured by using a sample obtained by filling about 0.2 g of powder into a tablet molding machine (10 mm φ) and molding the tablet at various pressing pressures using a manual hydraulic pump (P-1B-041 manufactured by Riken Seiki Co., Ltd.) (for example, 0.85 ton / cm 2 , 1.69 ton / cm 2 , 2.54 ton / cm 2 , etc.). The measurement is performed using an X'PertPro MPD powder X-ray diffractometer manufactured by PANalytical, Netherlands, so that the intensity ratio of the corresponding peak area can be calculated.

[0031] ·Average particle diameter (D 50 ) Average particle diameter (D 50) is usually 5 μm or more, preferably 10 μm or more, more preferably 25 μm or more, still more preferably 26 μm or more, particularly preferably 30 μm or more, most preferably 40 μm or more, and it is also preferable even if it is 45 μm or more, or 50 μm or more. Also, it is usually 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less. If it is too large, when formed into a molded body, the surface smoothness deteriorates, and there are more gaps between BN aggregated particles, etc., so the thermal conductivity tends not to improve. If it is too small, when formed into a molded body, the contact resistance between BN aggregated particles increases, and the thermal conductivity of the BN aggregated particles themselves tends to be low.

[0032] Note that D 50 means the particle diameter when the cumulative volume is exactly 50% when a cumulative curve is drawn with the volume of the powder used for measurement as 100%. As for the measurement method, in the case of the wet measurement method, for a sample in which BN aggregated particles are dispersed in a pure water medium containing sodium hexametaphosphate as a dispersion stabilizer, it can be measured using a laser diffraction / scattering particle size distribution measuring device, etc. In the case of the dry measurement method, it can be measured using "Morphologi" manufactured by Malvern.

[0033] ·Fracture strength The fracture strength of BN aggregated particles is usually 2.5 MPa or more, preferably 3.0 MPa or more, more preferably 3.5 MPa or more, still more preferably 4.0 MPa or more, and usually 20 MPa or less, preferably 15 MPa or less, more preferably 10 MPa or less. If it is too large, since the strength of the particles is too strong, when formed into a molded body, the surface smoothness deteriorates and the thermal conductivity tends to decrease. If it is too small, the particles are likely to deform under the pressure when producing the molded body, and the thermal conductivity tends not to improve.

[0034] Note that the fracture strength can be calculated by the following formula by subjecting one particle to a compression test according to JIS R 1639-5. Usually, the particles are measured at 5 points or more, and the average value is adopted. Formula: Cs = 2.48P / πd 2 Cs: Fracture strength (MPa) P: Destruction test force (N) d: Particle diameter (mm)

[0035] · Total pore volume The total pore volume of BN agglomerated particles is usually 2.2 cm 3 / g or less. Those with a small total pore volume have a dense interior in the BN agglomerated particles, so that the number of interfacial surfaces that inhibit heat conduction can be reduced This makes it possible to obtain BN agglomerated particles with higher thermal conductivity. If the total pore volume of the BN agglomerated particles is too large, when used as a filler in the composition, resin may be incorporated into the pores, and the apparent viscosity may increase, which may make it difficult to mold the composition or apply the coating solution

[0036] The lower limit value of the total pore volume of BN agglomerated particles is not particularly limited, but is usually 0.01 cm 3 / g. The total pore volume of the present invention is preferably 0.01 cm 3 / g or more, more preferably 0.02 cm 3 / g, preferably 2 cm 3 / g or less, more preferably 1.5 cm 3 / g or less The total pore volume of BN agglomerated particles in the aggregated BN powder can be measured by the nitrogen adsorption method and the mercury intrusion method

[0037] · Specific surface area The specific surface area of BN agglomerated particles is usually 1 m 2 / g or more, preferably 3 m 2 / g or more and 50 m 2 / g or less, more preferably 5 m 2 / g or more and 40 m 2 / g or less. Also, it is preferably 8 m 2 / g or less, and preferably 7.25 m 2 / g or less. When the specific surface area of BN agglomerated particles is within this range, when compounded with resin, the contact resistance between BN agglomerated particles tends to be reduced, and the increase in viscosity of the resin composition containing BN agglomerated particles can also be suppressed, which is preferable. The specific surface area can be measured by the BET one-point method (adsorbed gas: nitrogen)

[0038] · Bulk density When using BN agglomerated particles as a filler, in order to minimize the incorporation of the resin, it is better that the bulk density of the BN agglomerated particles is larger, usually 0.3 g / cm 3 or more, more preferably 0.35 g / cm 3 or more, still more preferably 0.4 g / cm 3 or more. When the bulk density of the BN agglomerated particles is too small, the apparent volume becomes large, and the volume of the added BN agglomerated particles increases with respect to the resin in the BN agglomerated particle-containing resin composition, and the incorporation of the resin increases. Also, the handleability of the BN agglomerated particles tends to deteriorate significantly. There is no particular limitation on the upper limit of the bulk density of the BN agglomerated particles, but it is usually 0.95 g / cm 3 or less, preferably 0.9 g / cm 3 or less, more preferably 0.85 g / cm 3 or less. When the bulk density of the BN agglomerated particles is too large, there is a tendency for uneven dispersion of the aggregated BN in the BN agglomerated particle-containing resin composition and for sedimentation to occur easily. Incidentally, the bulk density of the BN agglomerated particles can be determined using an ordinary apparatus and method for measuring the bulk density of powders.

[0039] [Manufacturing method of BN agglomerated particles] The BN agglomerated particles of the present invention can preferably be produced by granulating particles using a slurry containing raw material BN powder having a viscosity of 200 to 5000 mPa·s (hereinafter sometimes referred to as "BN slurry"), and heat-treating the granulated particles to grow the crystallites of h-BN primary particles constituting the BN agglomerated particles while maintaining the size of the granulated particles. The viscosity of the BN slurry is preferably 300 mPa·s or more, more preferably 500 mPa·s or more, still more preferably 700 mPa·s or more, particularly preferably 1000 mPa·s or more, and preferably 4000 mPa·s or less, more preferably 3000 mPa·s or less.

[0040] The viscosity of the above BN slurry is the average particle diameter D based on the volume of the generated BN agglomerated particles50 and significantly affects the average crystallite diameter of the h-BN primary particles constituting the BN aggregated particles. By setting the viscosity to 200 mPa·s or more, the average crystallite diameter of the h-BN primary particles and the volume-based average particle diameter D 50 of the BN aggregated particles can be increased. On the other hand, by setting the viscosity of the BN slurry to 5000 mPa·s or less, granulation can be facilitated. The method for preparing the viscosity of the BN slurry will be described later.

[0041] Note that the viscosity of the BN slurry in the present invention refers to the viscosity measured at a blade rotation speed of 100 rpm using a rotational viscometer "VISCO BASIC Plus R" manufactured by FUNGILAB. Furthermore, when producing a resin composition containing BN aggregated particles using the BN aggregated particles of the present invention as a filler, even at the same filling amount, the thermal conductivity of the molded body obtained can be dramatically improved as compared with other BN particles. This is presumably because in the BN aggregated particles of the present invention, the grain boundaries in the h-BN primary particles are reduced due to an increase in the average crystal particle diameter of the h-BN primary particles constituting the BN aggregated particles, and the specific surfaces of the h-BN primary particles constituting the BN aggregated particles are oriented. Preferably, the volume-based average particle diameter D 50 is large, which is considered to also affect the reduction of the contact resistance between the BN aggregated particles.

[0042] The BN aggregated particles of the present invention not only have high thermal conductivity of the BN aggregated particles themselves, but also have high thermal conductivity of the molded body produced by being compounded with a resin. That is, according to the present invention, a manufacturing method has been found that can increase the average crystallite diameter of the h-BN primary particles constituting the BN aggregated particles by controlling the slurry viscosity, which was not normally assumed to be controlled by those skilled in the art, within a specific range.

[0043] Furthermore, according to the present invention, a method for producing the BN aggregated particles defined in the present invention has been found by controlling the slurry viscosity within a specific range. Incidentally, the above peak area intensity ratio and the average crystallite diameter of the h-BN primary particles can also be controlled by the firing temperature during the heat treatment of the granulated particles produced from the BN slurry and the oxygen concentration present in the raw material BN powder. Specifically, as will be described later, by setting the firing temperature range during the heat treatment of the granulated particles produced from the BN slurry to 1800°C or higher and 2300°C or lower, the peak area intensity ratio can be made 0.25 or higher, and by using a raw material in which the oxygen concentration present in the raw material BN powder is 1.0% by weight or higher, the average crystallite diameter of the h-BN primary particles can be controlled within a desired range. That is, by using a raw material BN powder with an appropriate firing temperature range and an appropriate oxygen concentration, the above peak area intensity ratio and the above average crystallite diameter can be controlled simultaneously.

[0044] As a result, when the BN aggregated particles are made into a resin composition containing BN aggregated particles, the contact resistance between the BN aggregated particles is reduced, and the grain boundaries in the h-BN primary particles constituting the BN aggregated particles are reduced, and a specific crystal plane of the h-BN primary particles constituting the BN aggregated particles is oriented, so that highly thermally conductive BN aggregated particles can be produced. The BN aggregated particles obtained by the present invention can be designed in various sizes while maintaining high thermal conductivity, and thus can be applied to a wide range of uses as a molded body.

[0045] {Preparation of slurry} <Raw material BN powder> · Type of raw material BN powder As the raw material BN powder used in the present invention, commercially available h-BN, commercially available α- and β-BN, BN produced by the reduction nitridation method of a boron compound and ammonia, BN synthesized from a boron compound and a nitrogen-containing compound such as melamine, etc. can all be used without limitation, but h-BN is particularly preferably used in terms of more effectively exhibiting the effects of the present invention.

[0046] · Crystallinity of raw material BN powder As the form of the raw material BN powder used in the present invention, powdery BN particles with a wide half-value width of the peaks obtained by powder X-ray diffraction measurement and low crystallinity are preferable. That is, although it is also possible to use plate-shaped h-BN as the raw material, non-plate-shaped nanoparticles can also be preferably used. As a measure of crystallinity, the peak half-value width of the (002) plane obtained from powder X-ray diffraction measurement is usually 0.4° or more, preferably 0.45° or more, more preferably 0.5° or more at an angle of 2θ. And it is usually 2.0° or less, preferably 1.5° or less, and more preferably 1° or less. If it is larger than the above upper limit, the crystallites will not be large enough and it will take a long time to make them larger, so the productivity tends to deteriorate. If it is less than the above lower limit, the crystallinity is too high and sufficient crystal growth cannot be expected, and the dispersion stability during slurry preparation tends to deteriorate. The powder X-ray diffraction measurement method is described in the section of Examples below.

[0047] · Oxygen atom concentration in the raw material BN powder From the viewpoint of BN crystal growth, it is preferable that oxygen atoms are present in the raw material BN powder to a certain extent. In the present invention, the total oxygen concentration in the raw material BN powder is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and still more preferably 4% by mass or more. Also, it is usually 10% by mass or less, and more preferably 9% by mass or less. If it is larger than the above upper limit, oxygen tends to remain even after heat treatment, so the effect of improving thermal conductivity tends to be small. If it is less than the above lower limit, the crystallinity is too high and crystal growth cannot be expected, and the peak intensity ratio confirmed by powder X-ray diffraction measurement tends to deviate from the desired range.

[0048] In the present invention, by using a raw material in which the oxygen concentration present in the raw material BN powder is 1.0% by weight or more, the average crystallite size of the h-BN primary particles constituting the BN agglomerated particles can be controlled within a desired range. In addition, as a method for adjusting the total oxygen concentration of the raw material BN powder to the above range, for example, a method of performing BN synthesis at a low temperature of 1500°C or lower, a method of heat-treating the raw material BN powder in a low-temperature oxidation atmosphere of 500°C to 900°C, etc. can be mentioned. The total oxygen concentration of the raw material BN powder can be measured using an oxygen-nitrogen analyzer manufactured by Horiba, Ltd. by the inert gas fusion-infrared absorption method.

[0049] · Total pore volume and specific surface area of the raw material BN powder The total pore volume of the raw material BN powder is usually 1.0 cm 3 / g or less, preferably 0.3 cm 3 / g or more and 1.0 cm 3 / g or less, more preferably 0.5 cm 3 / g or more and 1.0 cm 3 / g or less. When the total pore volume is 1.0 cm 3 / g or less, the raw material BN powder is dense, enabling granulation with high sphericity.

[0050] The specific surface area of the raw material BN powder is usually 50 m 2 / g or more, preferably 60 m 2 / g or more, more preferably 70 m 2 / g or more. Usually, it is 1000 m 2 / g or less, preferably 500 m 2 / g or less, more preferably 300 m 2 / g or less. When the specific surface area of the raw material BN powder is 50 m 2 / g or more, it is preferable because the dispersed particle size in the BN slurry used for spheroidization by granulation can be reduced. Also, when it is 1000 m 2 / g or less, it is preferable because an increase in slurry viscosity can be suppressed. The total pore volume of the raw material BN powder can be measured by the nitrogen adsorption method and the mercury intrusion method, and the specific surface area can be measured by the BET one-point method (adsorbing gas: nitrogen). The specific measurement methods for the total pore volume and specific surface area of the raw material BN powder are described in the section of the examples below.

[0051] <Medium> There are no particular restrictions on the medium used for preparing the BN slurry, and water and / or various organic solvents can be used. However, from the viewpoints of ease of spray drying and simplification of equipment, it is preferable to use water, and pure water is more preferable.

[0052] The amount of the medium used for preparing the BN slurry is preferably added in an amount such that the viscosity of the BN slurry is 200 to 5000 mPa·s. Specifically, the amount of the medium used for preparing the BN slurry is usually 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and usually 70% by mass or less, preferably 65% by mass or less, more preferably 60% by mass or less. When the amount of the medium used is above the upper limit, the slurry viscosity becomes too low, so the uniformity of the BN slurry due to sedimentation, etc. is impaired, and the crystallite size of the h-BN primary particles constituting the obtained BN aggregated particles tends to deviate from the desired range. If it is less than the lower limit, the slurry viscosity is too high, so granulation tends to be difficult. That is, when the amount of the medium used is outside the above range, it becomes difficult to simultaneously satisfy the size of the BN aggregated particles, the crystallinity of the h-BN primary particles constituting the BN aggregated particles, and the reduction of the crystal grain boundaries in the h-BN primary particles.

[0053] <Surfactant> For the BN slurry, it is preferable to add various surfactants from the viewpoints of adjusting the viscosity of the slurry and the dispersion stability (aggregation suppression) of the raw material BN powder in the slurry. As the surfactant, anionic surfactants, cationic surfactants, nonionic surfactants, etc. can be used, and these may be used alone or in combination of two or more.

[0054] Generally, surfactants can change the viscosity of slurries. Therefore, when adding a surfactant to a BN slurry, the amount is adjusted so that the viscosity of the BN slurry becomes 200 to 5000 mPa·s. For example, when preparing a slurry with a solid content of 50% by mass using BN as the raw material, where the half-value width 2θ of the (002) plane peak obtained by powder X-ray diffraction measurement is 0.67° and the oxygen concentration is 7.5% by mass, usually, as the active ingredient of an anionic surfactant, it is added in an amount of usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 7% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, based on the total amount of the slurry. If it is greater than the above upper limit, the slurry viscosity decreases too much, and there is a tendency for a carbon component derived from the surfactant to easily remain in the generated BN agglomerated particles. If it is less than the above lower limit, the slurry viscosity becomes too high, and granulation itself tends to become difficult.

[0055] <Binder> The BN slurry may contain a binder in order to effectively granulate the raw material BN powder into particles. The binder acts to firmly bind h-BN primary particles and stabilize the granulated particles. The binder used in the BN slurry may be any that can enhance the adhesiveness between BN particles. However, in the present invention, since the granulated particles are heat-treated after granulation, those having heat resistance to the high-temperature conditions in this heat-treatment step are preferred.

[0056] As such binders, metal oxides such as aluminum oxide, magnesium oxide, yttrium oxide, calcium oxide, silicon oxide, boron oxide, cerium oxide, zirconium oxide, titanium oxide, etc. are preferably used. Among these, from the viewpoints of thermal conductivity as an oxide, heat resistance, and the binding force for binding BN particles to each other, aluminum oxide and yttrium oxide are suitable. Note that a liquid binder such as alumina sol may be used as the binder, or it may react during the heat treatment and be converted into other inorganic components. These binders may be used alone or in combination of two or more.

[0057] The usage amount of the binder (in the case of a liquid binder, the usage amount as a solid content) is usually 0 mass% or more and 30 mass% or less, preferably 0 mass% or more and 20 mass% or less, more preferably 0 mass% or more and 15 mass% or less, based on the raw material BN powder in the BN slurry. If it exceeds the above upper limit, the content of the raw material BN powder in the granulated particles decreases, which not only affects crystal growth but also reduces the effect of improving thermal conductivity when used as a thermal conductivity filler.

[0058] <Slurry preparation method> The slurry preparation method is not particularly limited as long as the raw material BN powder, the medium, and further, if necessary, the binder and the surfactant are uniformly dispersed and prepared within a desired viscosity range. However, when using the raw material BN powder, the medium, and further, if necessary, the binder and the surfactant, it is preferably prepared as follows.

[0059] Weigh a predetermined amount of the raw material BN powder into a resin bottle, and then add a predetermined amount of the binder. Further, after adding a predetermined amount of the surfactant, add zirconia-based ceramic balls and stir for about 0.5 to 5 hours on a pot mill turntable until the desired viscosity is reached. The order of addition is not particularly limited. However, when a large amount of raw material BN powder is slurried, aggregates such as lumps are likely to form. Therefore, after preparing an aqueous solution by adding a surfactant and a binder to water, a predetermined amount of raw material BN powder is added little by little, and zirconia-based ceramic balls are added thereto, and it may be dispersed and slurried using a pot mill turntable.

[0060] Also, for dispersion, in addition to a pot mill, a dispersion device such as a bead mill or a planetary mixer may be used. When slurrying, the temperature of the slurry is carried out at 10°C or higher and 60°C or lower. If it is lower than the lower limit, the slurry viscosity increases and tends to deviate from the desired viscosity range. If it is higher than the upper limit, the raw material BN powder is likely to decompose into ammonia in the aqueous solution. Usually, it is 10°C or higher and 60°C or lower, preferably 15°C or higher and 50°C or lower, more preferably 15°C or higher and 40°C or lower, and still more preferably 15°C or higher and 35°C or lower.

[0061] {Granulation} To obtain granulated particles from the BN slurry, general granulation methods such as spray drying method, rolling method, fluidized bed method, and stirring method can be used. Among these, the spray drying method is preferred. In the spray drying method, it is possible to produce granulated particles of a desired size depending on the concentration of the slurry as the raw material, the liquid feed rate per unit time introduced into the apparatus, the compressed air pressure and the compressed air volume when spraying the fed slurry, and it is also possible to obtain spherical granulated particles. There is no limitation on the spray drying apparatus to be used, but in order to obtain larger spherical granulated particles, the one using a rotary disk is optimal. Examples of such an apparatus include the spray dryer F series manufactured by Okawara Chemical Machinery Co., Ltd., and the spray dryer "MDL-050M" manufactured by Fujisaki Electric Co., Ltd.

[0062] When the average particle diameter of the granulated particles obtained by granulation is in the range of 25 μm or more and 200 μm or less based on the volume of the BN agglomerated particles of the present invention, the average particle diameter D based on volume 50It is usually preferably 15 μm or more and 150 μm or less, more preferably 20 μm or more and 100 μm or less. Here, the average particle diameter D of the granulated particles based on volume 50 can be measured, for example, by "LA920" manufactured by Horiba, Ltd. in the wet method and "Morphorogi" manufactured by Malvern in the dry method.

[0063] {Heat treatment} The above BN granulated particles can be used to produce BN aggregated particles by further heat-treating them in a non-oxidizing gas atmosphere. Here, the non-oxidizing gas atmosphere refers to an atmosphere such as nitrogen gas, helium gas, argon gas, ammonia gas, hydrogen gas, methane gas, propane gas, carbon monoxide gas, etc. The crystallization rate of the BN aggregated particles will differ depending on the type of atmosphere gas used here. In order to perform crystallization in a short time, nitrogen gas or a mixed gas in which nitrogen gas is used in combination with other gases is particularly preferably used. The heat treatment temperature is usually 1800 °C or more and 2300 °C or less, preferably 1900 °C or more, and also preferably 2200 °C or less. If the heat treatment temperature is too low, the growth of the average crystallites of the h-BN primary particles will be insufficient, and the thermal conductivity of the BN aggregated particles and the molded body may be reduced. If the heat treatment temperature is too high, there is a risk of decomposition of BN, etc.

[0064] By setting the above heat treatment temperature to 1800 °C or more and 2300 °C or less, the peak area intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of the h-BN primary particles can be set to a desired value. The heat treatment time is usually 5 hours or more and 20 hours or less, preferably 5 hours or more and 15 hours or less. If the heat treatment time is less than the above lower limit, crystal growth will be insufficient, and if it exceeds the above upper limit, there is a risk of partial decomposition of BN.

[0065] Since the heat treatment is carried out in a non-oxidizing gas atmosphere, preferably, usually, after evacuating the inside of the firing furnace using a vacuum pump, while introducing a non-oxidizing gas, it is heated to a desired temperature for temperature rise. However, when the inside of the firing furnace can be sufficiently replaced with a non-oxidizing gas, it may be heated and temperature-rise while introducing a non-oxidizing gas under normal pressure. Examples of the firing furnace include batch furnaces such as muffle furnaces, tubular furnaces, and atmosphere furnaces, and continuous furnaces such as rotary kilns, screw conveyor furnaces, tunnel furnaces, belt furnaces, pusher furnaces, and vertical continuous furnaces, which are used appropriately according to the purpose.

[0066] Usually, the granulated particles to be heat-treated are put into a crucible with a circular graphite lid and heated and fired in order to reduce the compositional non-uniformity during firing. At this time, in addition to reducing the compositional non-uniformity, a graphite partition may be inserted for the purpose of suppressing the sintering between BN agglomerated particles due to firing. The number of divisions by the partition is not particularly limited as long as sintering can be suppressed, but is usually 2 or more and 16 or less. If the number of divisions is more than the above upper limit, sintering can be suppressed, but the crystals of h-BN primary particles tend not to grow sufficiently. If the number of divisions is less than the above lower limit, sintering may proceed.

[0067] {Classification} The BN agglomerated particles after the above heat treatment are preferably classified in order to reduce the particle size distribution and suppress the increase in viscosity when blended in a resin composition containing BN agglomerated particles. This classification is usually carried out after the heat treatment of the granulated particles, but may be carried out on the granulated particles before the heat treatment and then subjected to the heat treatment.

[0068] The classification may be either wet or dry, but from the viewpoint of suppressing the decomposition of BN, dry classification is preferred. In particular, when the binder has water solubility, dry classification is particularly preferably used. For dry classification, in addition to classification by sieves, there is also air classification that classifies by the difference between centrifugal force and fluid resistance. It can also be carried out using classifiers such as a cyclone air classifier, a forced vortex centrifugal classifier, and a semi-free vortex centrifugal classifier. Among these, a cyclone air classifier is used to classify small fine particles in the sub-micron to single-micron range, and a semi-free vortex centrifugal classifier or the like is used to classify relatively larger particles. They can be appropriately selected according to the particle size of the particles to be classified.

[0069] [BN Agglomerated Particle-Containing Resin Composition] The BN agglomerated particle-containing resin composition of the present invention contains at least the BN agglomerated particles of the present invention and a resin. The BN agglomerated particles of the present invention are preferably used as a filler for the BN agglomerated particle-containing resin composition due to their morphological characteristics. The content ratio of the BN agglomerated particles in the BN agglomerated particle-containing resin composition (hereinafter sometimes referred to as "filler filling amount") is usually 5% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and usually 95% by mass or less, preferably 90% by mass or less, with the total of the BN agglomerated particles and the resin being 100% by mass. If it is greater than the above upper limit, the viscosity becomes too high and the moldability cannot be ensured, and the dense filling of the BN agglomerated particles is inhibited, so the thermal conductivity tends to decrease. If it is less than the above lower limit, although the moldability can be ensured, the amount of BN agglomerated particles is too small and the thermal conductivity tends not to improve.

[0070] [Resin] The resin used in the BN agglomerated particle-containing resin composition is not particularly limited, but is preferably a curable resin and / or a thermoplastic resin. For example, examples of the curable resin include thermosetting, photocuring, and electron beam curing. In terms of heat resistance, water absorption, dimensional stability, etc., thermosetting resins and / or thermoplastic resins are preferred, and among these, epoxy resins are more preferred. These resins may be used in combination of two or more.

[0071] The epoxy resin may be only an epoxy resin having one type of structural unit, or a combination of a plurality of epoxy resins having different structural units may be used. Further, the epoxy resin is used together with a curing agent for epoxy resin and a curing accelerator as necessary. When using an epoxy resin, its Tg is not particularly limited, but it is usually 0°C or higher, preferably 10°C or higher, more preferably 25°C or higher, and usually 350°C or lower, preferably 300°C or lower, more preferably 250°C or lower.

[0072] Here, in order to reduce voids in the cured product and obtain a cured product with high thermal conductivity in combination with coatability or film-forming property and adhesiveness, it is preferable to contain at least the following phenoxy resin (hereinafter sometimes referred to as "epoxy resin (A)") as the epoxy resin. The mass ratio of epoxy resin (A) to the total amount of epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, particularly preferably 16% by mass or more, and especially preferably 18% by mass or more, and is also preferably in the range of 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less.

[0073] The phenoxy resin generally refers to a resin obtained by reacting epihalohydrin with a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound with a divalent phenol compound. In the present invention, among these, a phenoxy resin having a high molecular weight with a weight average molecular weight of 10,000 or more is used as epoxy resin (A). Here, the weight average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography.

[0074] As the epoxy resin (A), a phenoxy resin having at least one skeleton selected from the group consisting of a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton and a dicyclopentadiene skeleton, a bisphenol A type phenoxy resin, a bisphenol F type phenoxy resin, a naphthalene type phenoxy resin, a phenol novolac type phenoxy resin, a cresol novolac type phenoxy resin, a phenol aralkyl type phenoxy resin, a biphenyl type phenoxy resin, a triphenylmethane type phenoxy resin, a dicyclopentadiene type phenoxy resin, a glycidyl ester type phenoxy resin, and a glycidylamine type phenoxy resin are preferable. Among them, a phenoxy resin having a fluorene skeleton and / or a biphenyl skeleton, a bisphenol A type phenoxy resin, and a bisphenol F type phenoxy resin are particularly preferable because the heat resistance and adhesion are further enhanced. These may be used alone or in combination of two or more.

[0075] In addition to the above epoxy resin (A), the epoxy resin according to the present invention preferably contains an epoxy resin having two or more epoxy groups in the molecule (hereinafter sometimes referred to as "epoxy resin (B)"). Examples of the epoxy resin (B) include various epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, and polyfunctional phenol type epoxy resin. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidylamine type epoxy resin, and polyfunctional phenol type epoxy resin are preferable in terms of improving heat resistance and adhesion. These may be used alone or in combination of two or more. These may be used alone or in combination of two or more.

[0076] From the perspective of controlling the melt viscosity, the weight-average molecular weight of the above epoxy resin (B) is preferably 100 to 5000, more preferably 200 to 2000. When the weight-average molecular weight is lower than 100, the heat resistance tends to be poor, and when it is higher than 5000, the melting point of the epoxy resin becomes high, and the workability tends to decrease.

[0077] In addition, the epoxy resin according to the present invention may contain an epoxy resin other than the epoxy resin (A) and the epoxy resin (B) (hereinafter sometimes referred to as "other epoxy resin") as long as the object is not impaired. The content of the other epoxy resin is usually 50% by mass or less, preferably 30% by mass or less, based on the total of the epoxy resin (A) and the epoxy resin (B).

[0078] In the resin composition containing BN agglomerated particles of the present invention, the proportion of the epoxy resin (A) in all the epoxy resins including the epoxy resin (A) and the epoxy resin (B) is preferably 5 to 95% by mass, preferably 10 to 90% by mass, more preferably 20 to 80% by mass, with the total of all the epoxy resins being 100% by mass as described above. Note that "all the epoxy resins including the epoxy resin (A) and the epoxy resin (B)" means the total of the epoxy resin (A) and the epoxy resin (B) when the epoxy resins contained in the resin composition containing BN agglomerated particles of the present invention are only the epoxy resin (A) and the epoxy resin (B), and means the total of the epoxy resin (A), the epoxy resin (B), and the other epoxy resin when other epoxy resins are further included.

[0079] When the proportion of the epoxy resin (A) is equal to or higher than the above lower limit, the effect of improving the thermal conductivity by blending the epoxy resin (A) can be sufficiently obtained, and the desired high thermal conductivity can be obtained. When the proportion of the epoxy resin (A) is equal to or lower than the above upper limit, particularly when the epoxy resin (B) is 10% by mass or more of all the epoxy resins, the blending effect of the epoxy resin (B) is exerted, and the curability and the physical properties of the cured product become sufficient.

[0080] The curing agent for epoxy resin is appropriately selected according to the type of resin used. For example, acid anhydride-based curing agents and amine-based curing agents can be mentioned. Examples of acid anhydride-based curing agents include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and benzophenone tetracarboxylic anhydride. Examples of amine-based curing agents include aliphatic polyamines such as ethylenediamine, diethylenetriamine, and triethylenetetramine, aromatic polyamines such as diaminodiphenyl sulfone, diaminodiphenyl methane, diaminodiphenyl ether, and m-phenylenediamine, and dicyandiamide. These can be used alone or in combination of two or more. These curing agents for epoxy resin are usually blended in the range of 0.3 or more and 1.5 or less in terms of equivalent ratio with respect to the epoxy resin.

[0081] The curing accelerator is appropriately selected according to the types of resin and curing agent used. For example, as the curing accelerator for the acid anhydride-based curing agent, boron trifluoride monoethylamine, 2-ethyl-4-methylimidazole, 1-isobutyl-2-methylimidazole, 2-phenyl -4-methylimidazole can be mentioned. These can be used alone or in combination of two or more. These curing accelerators are usually used in the range of 0.1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the epoxy resin.

[0082] Also, the resin of the resin composition containing BN agglomerated particles of the present invention may be a thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins such as polyethylene resin, polypropylene resin, and ethylene-vinyl acetate copolymer resin; polyester resins such as polyethylene terephthalate resin, polybutylene terephthalate resin, and liquid crystal polyester resin; polyvinyl chloride resin, phenoxy resin, acrylic resin, polycarbonate resin, polyphenylene sulfide resin, polyphenylene ether resin, polyamide resin, polyamideimide resin, polyimide resin, polyetheramideimide resin, polyetheramide resin, and polyetherimide resin. Further, copolymers such as their block copolymers and graft copolymers are also included. These may be used alone or in combination of two or more.

[0083] Also, the resin of the resin composition containing BN agglomerated particles of the present invention may contain a rubber component. Examples of the rubber component include natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, butadiene-acrylonitrile copolymer rubber, isobutylene-isoprene copolymer rubber, chloroprene rubber, silicone rubber, fluororubber, chlorosulfonated polyethylene, and polyurethane rubber. These may be used alone or in combination of two or more.

[0084] <Other components> The resin composition containing BN agglomerated particles of the present invention may further contain additional components within the scope where the effects of the present invention can be obtained. Such additional components include, for example, in addition to the resins described above, aluminum nitride, silicon nitride which are inorganic fillers, nitride particles such as fibrous, plate-like, particulate agglomerated BN, alumina, fibrous alumina, zinc oxide, magnesium oxide, beryllium oxide, titanium oxide and other insulating metal oxides, diamond, fullerene, aluminum hydroxide, magnesium hydroxide and other inorganic fillers, surface treatment agents such as silane coupling agents that improve the interfacial adhesion strength between the inorganic filler and the matrix resin, insulating carbon components such as reducing agents, resin curing agents, resin curing accelerators, viscosity modifiers, and dispersion stabilizers. Among these, nitride particles are preferred, and particulate agglomerated BN is more preferred, from the viewpoints of improving thermal conductivity and breakdown voltage.

[0085] Also, from the viewpoint of reducing the viscosity of the resin composition containing BN agglomerated particles, a solvent can be used in the resin composition containing BN agglomerated particles of the present invention. As the solvent, a solvent that dissolves the resin is used from known solvents. Such solvents include, for example, methyl ethyl ketone, acetone, cyclohexanone, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene, phenol, and hexafluoroisopropanol. These may be used alone or in combination of two or more.

[0086] The solvent is usually used in the range of 0 to 10,000 parts by mass with respect to 100 parts by mass of the resin such as epoxy resin.

[0087] [Method for producing resin composition containing BN agglomerated particles] The resin composition containing BN agglomerated particles of the present invention can be obtained by uniformly mixing the BN agglomerated particles, resin, and other components added as necessary of the present invention by stirring or kneading. For such mixing, for example, general kneading devices such as mixers, kneaders, single-screw or twin-screw kneaders can be used, and heating may be performed as necessary during mixing.

[0088] In addition, when the system contains a solvent or the resin is in a liquid state, and the composition containing BN aggregated particles of the present invention is in a slurry state having fluidity (also referred to as a coating slurry in this specification), the preparation method for making the slurry is not particularly limited, and conventionally known methods can be used. At this time, for the purpose of improving the uniformity of the coating solution, defoaming, etc., it is preferable to mix and stir using general kneading devices such as a paint shaker, bead mill, planetary mixer, stirring type disperser, self-revolving and revolving stirring mixer, three-roll mill, kneader, single-screw or twin-screw kneader, etc. The mixing order of each compounding component is arbitrary as long as there are no particular problems such as reactions or precipitates occurring. For example, the resin is mixed and dissolved in an organic solvent (for example, methyl ethyl ketone) to prepare a resin solution, and to the obtained resin solution, a mixture obtained by sufficiently mixing BN aggregated particles and other components described later is added and mixed. Then, after further adding an organic solvent for viscosity adjustment and mixing, further, methods such as adding additives such as a resin curing agent, curing accelerator, or dispersant and mixing can be mentioned.

[0089] [Molded Body of BN Aggregated Particles] The molded body of the present invention is a molded body using the BN aggregated particles of the present invention, preferably a molded body formed by molding a resin composition containing BN aggregated particles. As the molding method of the molded body, generally used methods can be used. For example, when the resin composition containing BN aggregated particles of the present invention has plasticity or fluidity, it can be molded by curing the resin composition containing BN aggregated particles in a desired shape, for example, in a state of being accommodated in a mold.

[0090] In the production of such a molded body, injection molding, injection compression molding, extrusion molding, compression molding, and vacuum compression molding can be utilized. When the above slurry contains a solvent, the solvent can be removed by known heating methods such as a hot plate, hot air furnace, IR heating furnace, vacuum dryer, high-frequency heater, etc. In addition, when the resin composition containing BN aggregated particles of the present invention is a thermosetting resin composition such as an epoxy resin or a silicone resin, the molding of the molded body, that is, the curing, can be carried out under the respective curing temperature conditions.

[0091] Also, when the resin composition containing BN agglomerated particles of the present invention is a thermoplastic resin composition, the molding of the molded body can be carried out under conditions of a temperature equal to or higher than the melting temperature of the thermoplastic resin and a predetermined molding speed and pressure. In addition, the molded body of the present invention can also be obtained by cutting the cured product of the resin composition containing BN agglomerated particles of the present invention into a desired shape.

[0092] As the use of the BN agglomerated particles of the present invention, a heat dissipation sheet is preferable among molded bodies. The manufacturing method of the heat dissipation sheet is not particularly limited and can be manufactured by the manufacturing method of the conventional heat dissipation sheet.

[0093] In addition, the circuit board having the heat dissipation sheet of the present invention or the copper-bonded heat dissipation sheet molded using BN agglomerated particles (these are collectively referred to as sheets in this specification) has a high heat dissipation effect due to high thermal conductivity, and under high reliability, high output and high density of the device are possible. Therefore, it is suitable as a heat dissipation substrate or a heat dissipation sheet for a power semiconductor device. In a power semiconductor device, members such as aluminum wiring, a sealing material, a package material, a heat sink, a thermal paste, and solder other than the heat dissipation sheet of the present invention can be appropriately adopted from conventionally known members.

[0094] In addition, the sheet of the present invention is a sheet containing at least boron nitride agglomerated particles (A), and in the sheet, the peak intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of the h-BN primary particles in the sheet obtained by X-ray diffraction measurement is 1.0 or more. This peak intensity ratio ((100) / (004)) is preferably 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more, and particularly preferably 3.0 or more. The upper limit is not particularly limited, but is usually 10.0 or less, preferably 7.0 or less, and more preferably 5.0 or less.

[0095] Furthermore, the average crystallite size of the h-BN primary particles in the sheet determined from the (002) plane peak of the h-BN primary particles in the sheet obtained by X-ray diffraction measurement of the sheet is not particularly limited, but is usually 300 Å or more, preferably 320 Å or more, more preferably 375 Å or more, still more preferably 380 Å or more, even more preferably 390 Å or more, particularly preferably 400 Å or more, and is usually 5000 Å or less, preferably 2000 Å or less, more preferably 1000 Å or less. It is preferable that the sheet is such a sheet.

[0096] The sheet of the present invention is a sheet containing at least boron nitride agglomerated particles (A). In the sheet, the peak area intensity ratio ((100) / (004)) of the (100) plane and the (004) plane of the h-BN primary particles in the sheet obtained by X-ray diffraction measurement is not particularly limited, but is usually 0.6 or more, preferably 0.65 or more, preferably 0.7 or more, more preferably 0.75 or more, still more preferably 0.8 or more, particularly preferably 0.85 or more. The upper limit is not particularly limited, but is usually 10.0 or less, preferably 5.0 or less, more preferably 4.0 or less.

[0097] In addition, the thermal conductivity (W / mK) of the heat dissipation sheet is not particularly limited, but is usually 5 W / mK or more, preferably 10 W / mK or more, more preferably 13 W / mK, particularly preferably 15 W / mK or more, and particularly preferably 17 W / mK or more. The withstand voltage performance is usually 10 kV / mm or more, preferably 15 kV / mm or more, particularly preferably 20 kV / mm or more. The glass transition temperature of the sheet of the present invention is usually 100 °C or more, preferably 130 °C or more, particularly preferably 175 °C or more.

Examples

[0098] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Note that various conditions and values of evaluation results in the following examples indicate the preferable ranges in the embodiments of the present invention as well. The preferable range of the present invention can be determined in consideration of the preferable ranges in the above-described embodiments and the ranges indicated by the values in the following examples or combinations of the values among the examples.

[0099] {Measurement conditions} The properties in the present invention were measured by the methods described below. · Slurry viscosity: Measured using a rotational viscometer “VISCO BASIC Plus R” manufactured by FUNGILAB at a blade rotation speed of 100 rpm.

[0100] · Average particle diameter (D 50 ) of BN agglomerated particles: The average particle diameter D 50 (μm) of BN agglomerated particles was measured using “Morphologi” manufactured by Malvern.

[0101] · Average crystallite diameter of h-BN primary particles: The average crystallite diameter was determined from the peak derived from the (002) plane of h-BN primary particles obtained by powder X-ray diffraction measurement using the Scherrer equation. The powder X-ray diffraction measurement was performed using an X-ray diffractometer “X‘Pert Pro MPD” manufactured by PANalytical. The Scherrer equation is as follows. D = (K·λ) / (β·cosθ) Here, D: crystallite diameter, K: Scherrer constant, λ: X-ray (CuKα1) wavelength, β : peak half-width, θ: Bragg angle derived from CuKα1. Also, β was obtained using the following correction formula . β = (β o 2 - β i 2 ) 0.5 Here, β iis the full width at half maximum derived from the apparatus determined by standard Si, and β o is the peak full width at half maximum derived from the (002) plane of h-BN. The values of each constant are as follows. K = 0.9, λ = 1.54059 Å

[0102] · (100) / (004) peak area intensity ratio of h-BN primary particles: A tableting machine (10 mm φ) was filled with approximately 0.2 g of BN agglomerated particles, and using a manual hydraulic pump (P-1B-041 manufactured by Riken Seiki Co., Ltd.), tableting was performed at a pressing pressure of 0.85 ton / cm 2 . For the obtained sample, using the same apparatus as for powder X-ray diffraction measurement, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of h-BN primary particles was determined. The results are shown in Table 1.

[0103] · Thermal conductivity in the thickness direction of the molded body The thermal diffusivity in the thickness direction of the molded body was measured using a thermal diffusivity measuring device "ai-Phase Mobile 1u" manufactured by AI Phase Co., Ltd. and determined as follows. Thermal conductivity in the thickness direction of the molded body = Thermal diffusivity in the thickness direction of the molded body × Specific gravity of the molded body × Specific heat of the molded body

[0104] Production of BN agglomerated particles, resin composition containing BN agglomerated particles, and molded article (Example 1) [Preparation of BN Agglomerated Particles from BN Slurry] [Preparation of BN Slurry (Slurry A)] (Raw materials) Raw material h-BN powder (the full width at half maximum of the (002) plane peak obtained by powder X-ray diffraction measurement is 2θ = 0.67°, and the oxygen concentration is 7.5 mass%): 10000 g Binder ("Taxeram M160L" manufactured by Taki Chemical Co., Ltd., solid content concentration 21 mass%): 11496 g Surfactant (surfactant "Ammonium Lauryl Sulfate" manufactured by Kao Corporation: solid content concentration 14 mass%): 250 g (Preparation of slurry) A predetermined amount of raw material h-BN powder was weighed into a resin bottle, and then a predetermined amount of binder was added. Further, after adding a predetermined amount of surfactant, zirconia-based ceramic balls were added and stirred on a pot mill turntable for 1 hour. The viscosity of the slurry was 810 mPa·s.

[0105] [Granulation] Granulation from the BN slurry was carried out using FOC-20 manufactured by Okawara Chemical Industries Co., Ltd. at a disk rotation speed of 20000 - 23000 rpm and a drying temperature of 80 °C to obtain spherical BN aggregated particles.

[0106] [Preparation of BN Aggregated Particles (BN-A Aggregated Particles)] After evacuating the above BN granulated particles at room temperature, nitrogen gas was introduced to restore the pressure, and while introducing nitrogen gas as it was, the temperature was raised to 2000 °C at 83 °C / hour. After reaching 2000 °C, it was held for 5 hours while introducing nitrogen gas as it was. Then, it was cooled to room temperature to obtain spherical BN-A aggregated particles having a card house structure.

[0107] [Classification] Furthermore, after lightly pulverizing the BN-A aggregated particles after the above heat treatment using a mortar and pestle, classification was carried out using a sieve with an opening size of 90 μm. After classification, the average crystallite size of the h-BN primary particles constituting the BN-A aggregated particles, the peak intensity ratio of the (100) plane and (004) plane of the h-BN primary particles ((100) / (004)), and the D of the BN-A aggregated particles 50 were measured. The measurement results are shown in Table 1.

[0108] [Manufacture of Formed Body Sheet] The BN-A aggregated particles obtained above were used as a filler to prepare a BN aggregated particle-containing resin composition composed of the filler and a resin composition. [Resin Composition] The epoxy resins "157S70", "828US", "4275" manufactured by Mitsubishi Chemical Corporation and the curing agent "C11Z-CN" manufactured by Shikoku Kasei Kogyo Co., Ltd. were mixed at a ratio of "157S70":"828US":"4275":"C11Z-CN" = 1:0.25:0.25:0.11 (mass ratio) to obtain a resin composition.

[0109] [Preparation of Resin Composition Containing BN Agglomerated Particles] BN-A (BN agglomerated particles) and the above resin composition were blended so that the filling amount of BN-A agglomerated particles (the content ratio of BN- agglomerated particles to the total of the resin composition and BN-A agglomerated particles) was 80% by mass. 100 parts by mass of the prepared resin composition / BN-A agglomerated particle mixture and 50 parts by mass of methyl ethyl ketone were placed in a polypropylene cup with a lid. Further, 6 parts by mass of 1-cyanoethyl-2-undecylimidazole (curing agent) was added to 100 parts by mass of the resin composition components, and they were mixed using a planetary stirrer ("Bubble Removal Rentaro AR-250" manufactured by Shinki Co., Ltd.) to prepare a coating liquid of the resin composition containing BN agglomerated particles.

[0110] [Coating] The obtained coating liquid of the resin composition containing BN agglomerated particles was applied onto a copper substrate with a thickness of 100 μm and a size of 10 cm × 20 cm using a bar coater (Auto Film Applicator manufactured by Tester Sangyo Co., Ltd.) with a gap interval of 400 μm. Then, vacuum drying was performed at 50°C for 30 minutes to form a coating film on the copper substrate.

[0111] [Manufacture of Molded Body] The copper plate with the obtained coating film formed was cut into a 4 cm square. It was placed in a mold and hot pressed at 130°C and 500 kg / cm 2 for 3 minutes, and then cured in an oven at 160°C for 2 hours to obtain a molded body (4 cm × 4 cm) for thermal conductivity evaluation. The measurement results are shown in Table 1.

[0112] (Example 2) In Example 1, a BN slurry (Slurry B) was prepared by changing the blending ratio of the raw materials as follows. Except for this, the procedure was the same as in Example 1, and spherical BN agglomerated particles (Agglomerated BN-B) having a card house structure, a resin composition containing BN agglomerated particles, and a molded body were produced. The measurement results are shown in Table 1.

[0113] [BN Slurry (Slurry B)] (Raw Materials) Raw material h-BN powder: 10000 g Pure water: 7500 g Binder: 5750 g Surfactant: 250 g (Slurry Preparation) A predetermined amount of the raw material h-BN powder was weighed into a resin bottle, and then predetermined amounts of pure water and binder were added in this order. Furthermore, after adding a predetermined amount of surfactant, zirconia-based ceramic balls were added and stirred on a pot mill turntable for 1 hour. The viscosity of the slurry was 2200 mPa·s.

[0114] (Example 3) In Example 1, a BN slurry (Slurry C) was prepared by changing the blending ratio of the raw materials as follows. Except for this, the procedure was the same as in Example 1, and spherical BN agglomerated particles (Agglomerated BN-C) having a card house structure, a resin composition containing BN agglomerated particles, and a molded body were produced. The measurement results are shown in Table 1.

[0115] [BN Slurry (Slurry C)] (Raw Materials) Raw material h-BN powder: 10000 g Binder: 11496 g Surfactant: 250 g (Slurry Preparation) A predetermined amount of the raw material h-BN powder was weighed into a resin bottle, and then a predetermined amount of binder was added. Furthermore, after adding a predetermined amount of surfactant, zirconia-based ceramic balls were added and stirred on a pot mill turntable for 1 hour. The viscosity of the slurry was 1600 mPa·s.

[0116] (Comparative Example 1) The slurry B in Example 2 was used as the following slurry D with the composition ratio of raw materials changed, and the same procedures as in Example 2 were carried out to prepare BN agglomerated particles (BN-D agglomerated particles), a resin composition containing BN agglomerated particles, and a molded body. The viscosity of the slurry was 155 mPa·s. The measurement results are shown in Table 1.

[0117] [BN Slurry (Slurry D)] Slurry D formulation (Raw materials) Raw material h-BN powder: 2400 g Pure water: 2199 g Binder: 1380 g Surfactant: 60 g

[0118] (Comparative Example 2) The slurry was prepared and granulated in the same manner as in Example 1, and BN agglomerated particles (agglomerated BN-E) were prepared in the same manner as in Example 1 except that the firing temperature during the production of BN agglomerated particles was 1300 °C and the holding time was 24 h. Using these BN agglomerated particles, a resin composition containing BN agglomerated particles and a molded body were produced in the same manner as in Example 1. The results are shown in Table 1.

[0119] (Comparative Example 3) A resin composition containing BN agglomerated particles and a molded body were produced in the same manner as in Example 1, except that PTX60 manufactured by Momentive was used instead of the BN-A agglomerated particles in Example 1. The results are shown in Table 1.

[0120] (Comparative Example 4) The same procedures as in Example 1 were carried out, except that PTX25 manufactured by Momentive was used instead of the BN-A agglomerated particles in Example 1. The results are shown in Table 1.

[0121] (Comparative Example 5) A resin composition containing BN agglomerated particles and a molded body were produced in the same manner as in Example 1, except that SGPS manufactured by Denki Kagaku Kogyo Co., Ltd. was used instead of the BN-A agglomerated particles in Example 1. The results are shown in Table 1.

[0122] (Comparative Example 6) The BN-aggregate particle-containing resin composition and the molded article were produced in the same manner as in Example 1, except that CTS7M manufactured by Shungo Ban Co., Ltd. was used instead of the BN-A aggregate particles of Example 1. The results are shown in Table 1.

[0123] (Comparative Example 7) Slurry preparation and granulation were carried out in the same manner as in Example 1, and BN aggregate particles (aggregated BN-F) were produced in the same manner as in Example 1, except that the firing temperature during the production of the BN aggregate particles was 1600 °C and the holding time was 24 h. Using these BN aggregate particles, a BN-aggregate particle-containing resin composition was produced and a molded article was manufactured in the same manner as in Example 1. The results are shown in Table 1.

[0124] (Comparative Example 8) In Example 2, the same procedure as in Example 1 was carried out, except that the mixing ratio of the raw materials of Slurry B was changed to the following BN slurry (Slurry E).

[0125] [BN Slurry (Slurry E)] (Raw Materials) Raw material h-BN powder: 10000 g Pure water: 7750 g Binder: 5750 g (Slurry Preparation) A predetermined amount of the raw material h-BN powder was weighed into a resin bottle, and then predetermined amounts of pure water and binder were added in this order. Further, zirconia-based ceramic balls were added and stirred on a pot mill turntable for 1 hour. The viscosity of the slurry was 8000 mPa·s.

[0126]

Table 1

[0127] Evaluation of peak area intensity ratio of (100) / (004) plane of h-BN primary particles in BN agglomerated particle compression molded article Example 4 An ingot molding machine (10 mm in diameter) was filled with about 0.2 g of the BN-A aggregated particles prepared in Example 1, and using a manual hydraulic pump (P-1B-041 manufactured by Riken Seiki Co., Ltd.), ingots were molded at various pressing pressures described in Table 2. For the obtained samples, using the same apparatus as in the powder X-ray diffraction measurement, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined. The results are shown in Table 2.

[0128] Example 5 An ingot molding machine (10 mm in diameter) was used with about 0.2 g of the BN-B aggregated particles prepared in Example 2 as the BN aggregated particles, and in the same manner as in Example 3, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined. The results are shown in Table 2.

[0129] Comparative Example 9 Except for using BN-E aggregated particles as the BN aggregated particles, in the same manner as in Example 3, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined. The results are shown in Table 2.

[0130] Comparative Example 10 Except for using Momentive's PTX60 aggregated particles as the BN aggregated particles, in the same manner as in Example 3, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined. The results are shown in Table 2.

[0131] Comparative Example 11 Except for using Momentive's PTX25 as the BN aggregated particles, in the same manner as in Example 3, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined. The results are shown in Table 2.

[0132] Comparative Example 12 Except for using SGPS manufactured by Denki Kagaku Kogyo Co., Ltd. as the BN aggregated particles, in the same manner as in Example 3, the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined. The results are shown in Table 2.

[0133] Comparative Example 13 The peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined in the same manner as in Example 3, except that CTS7M manufactured by Sango Ban Co., Ltd. was used as the BN agglomerated particles. The results are shown in Table 2.

[0134] Comparative Example 14 The peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles was determined in the same manner as in Example 3, except that BN-F agglomerated particles were used as the BN agglomerated particles. The results are shown in Table 2.

[0135] [Table 2]

[0136] From Table 1, it can be seen that by using the BN agglomerated particles of the present invention, a high thermal conductivity is exhibited as a molded body. In the comparative examples where the average crystallite size of the h-BN primary particles is less than 375 Å, the thermal conductivity is low, and even in those where the average crystallite size exceeds 375 Å, the comparative examples where the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles by powder X-ray diffraction measurement is 0.25 or less cannot achieve a high thermal conductivity. Therefore, the BN agglomerated particles of the present invention, in which the average crystallite size of the h-BN primary particles constituting the BN agglomerated particles is 375 Å or more and the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles by powder X-ray diffraction measurement is 0.25 or more, exhibit unprecedented performance as a thermal conductivity filler and can be widely applied to various applications such as the electric and electronic fields where there are many thermal problems.

[0137] Furthermore, from the results in Table 1 and Table 2, by using agglomerated particles in which the peak area intensity ratio ((100) / (004)) of the (100) plane and (004) plane of the h-BN primary particles is 0.25 or more even at a pressure above a specific pressure and the average crystallite size of the h-BN primary particles is larger than 375 Å, a sheet having high thermal conductivity in the thickness direction can be obtained.

Industrial Applicability

[0138] By using the BN agglomerated particles of the present invention, for example, a high-quality heat dissipation sheet having high thermal conductivity required for a power semiconductor device can be formed. The power semiconductor device having the heat dissipation sheet is useful for manufacturing a power semiconductor device using a high-efficiency substrate capable of high-temperature operation, such as next-generation SiC and GaN.

Claims

1. Boron nitride agglomerated particles (hereinafter referred to as "BN agglomerated particles") formed by aggregation of boron nitride primary particles (hereinafter referred to as "BN primary particles"), having a specific surface area of 1 m ２ / g or more and 8 m ２ / g or less, having an average particle diameter (D ５０ ) of 26 μm or more, wherein the BN primary particles are h-BN primary particles, the major axis of the BN primary particles is 3 μm or less, the (100) / (004) peak area intensity ratio of the (100) plane and the (004) plane of the BN primary particles, obtained by powder X-ray diffraction measurement of a pellet-shaped sample obtained by molding at a molding pressure of 0.85 ton / cm ２ with a 10 mmφ powder tablet molding machine, is 0.40 or more and 1.2 or less, and the average crystallite diameter of the BN primary particles obtained by powder X-ray diffraction measurement of the BN agglomerated particles filled in a glass sample plate with a depth of 0.2 mm so that the surface is smooth is 375 Å or more and 415 Å or less. BN agglomerated particles characterized by the above.

2. The BN agglomerated particles according to claim 1, which are spherical.

3. The BN agglomerated particles according to claim 1 or 2, wherein the BN agglomerated particles have a card house structure.

4. A resin and a BN agglomerated particle-containing resin composition containing the BN agglomerated particles according to any one of claims 1 to 3.

5. The BN agglomerated particle-containing resin composition according to claim 4, wherein the content ratio of the BN agglomerated particles in the BN agglomerated particle-containing resin composition is 5% by mass or more and 95% by mass or less when the total of the BN agglomerated particles and the resin is 100% by mass.

6. The BN agglomerated particle-containing resin composition according to claim 4 or 5, wherein the resin is a thermosetting resin and / or a thermoplastic resin.

7. A molded article containing the BN agglomerated particles according to any one of claims 1 to 3.

8. A molded article obtained by molding the resin composition containing BN agglomerated particles according to any one of Claims 4 to 6.

9. A power semiconductor device including the molded article according to Claim 7 or 8.

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