The present invention relates to aggregated boron nitride particles including hexagonal boron nitride primary particles aggregated, including a spacer type coupling agent. The thermally conductive resin composition of the present invention includes the aggregated boron nitride particles of the present invention. The heat dissipation member of the present invention includes the thermally conductive resin composition of the present invention. According to the present invention, aggregated boron nitride particles that can suppress the formation of voids in a heat dissipation member produced by mixing with a resin, a thermally conductive resin composition including the aggregated boron nitride particles, and a heat dissipation member using the thermally conductive resin composition can be provided.

A composition (or an aggregate) comprising an epitaxial h-BN/BNNT structure that comprises a hexagonal boron nitride structure that is epitaxial with respect to a boron nitride nanotube structure. Also, a composition (or an aggregate) that comprises independent boron nitride nanotubes, in which a total mass percentage of independent hexagonal boron nitride and residual boron in the composition is not more than 35%. Also, a composition (or an aggregate) in which not more than 1% of independent boron nitride nanotubes and boron nitride nanotube structures have a dixie cup or bamboo defect. Also, a composition in which at least 50% of independent boron nitride nanotubes and boron nitride nanotube structures are single-wall. Also, a method of making a composition that comprises epitaxial h-BN/BNNT structures.

A surface-treated aggregated boron nitride powder is prepared by using the boron nitride powder as the raw material, adding an oxidizer to the boron nitride aggregated grains, wet-pulverizing or wet-crushing the grains for surface modification treatment of the particles and allowing reaction of the particles with a metal coupling agent. The surface-treated boron nitride aggregated grains are formed by aggregation of hexagonal h-BN primary particles; (B) have any one or more of Si, Ti, Zr, Ce, Al, Mg, Ge, Ga, and V in an amount of 0.1 atm % or more and 3.0 atm % or less in its composition on the surface of 10 nm; (C) have a crushing strength of 5 MPa or more; and (D) have an average particle diameter of 20 μm or more and 100 μm or less.

A surface-treated aggregated boron nitride powder is prepared by using the boron nitride powder as the raw material, adding an oxidizer to the boron nitride aggregated grains, wet-pulverizing or wet-crushing the grains for surface modification treatment of the particles and allowing reaction of the particles with a metal coupling agent. The surface-treated boron nitride aggregated grains are formed by aggregation of hexagonal h-BN primary particles; (B) have any one or more of Si, Ti, Zr, Ce, Al, Mg, Ge, Ga, and V in an amount of 0.1 atm % or more and 3.0 atm % or less in its composition on the surface of 10 nm; (C) have a crushing strength of 5 MPa or more; and (D) have an average particle diameter of 20 μm or more and 100 μm or less.

A method for purifying a boron nitride nanotube feedstock is disclosed, including an initial step of mixing a boron nitride nanotube (BNNT) feedstock with a solvent to form an initial mixture. This BNNT feedstock is made up of hexagonal boron nitride (h-BN) particles and less than about 50 weight percent BNNTs on a dry basis. This initial mixture is then sonicated within a treatment vessel using an ultrasonic probe. At least a portion of the initial mixture is filtered out of the treatment vessel and across a nanoporous membrane at the same as the sonication. In this manner, the method provides a filtrate which is enriched in h-BN particles relative to the initial mixture and a retentate which is enriched in BNNTs relative to the initial mixture.

An insulating filler composed of a mixed powder in which a hydrophobic fumed oxide powder having an average primary particle size D.sub.1, which is smaller than an average primary particle size D.sub.2, is adhered to the surface of a magnesium oxide powder and/or a nitride-based inorganic powder having the average primary particle size D.sub.2, wherein: the ratio D.sub.1/D.sub.2 of the average primary particle size D.sub.1 to the average primary particle size D.sub.2 is 6×10.sup.−5 to 3×10.sup.−3; the volume resistivity of the mixed powder is 1×10.sup.11 Ω.Math.m or more; and the content ratio of the hydrophobic fumed oxide powder in the mixed powder is 5-30 mass %. Also provided is an insulating material in which the above-mentioned insulating filler is contained in a resin molded body.

In an embodiment, a method includes liberating feed atoms and forming at least one nanotube from the liberated feed atoms. Feed atoms disposed over a front side of a substrate are liberated in response to electromagnetic radiation that propagates from the back side of the substrate, through the substrate, to the front side of the substrate. And, from the liberated feed atoms, at least one nanotube is formed over the front side of the substrate in response to at least one catalyst separate from the substrate and disposed over the front side of the substrate and over the feed atoms.

In an embodiment, a method includes liberating feed atoms and forming at least one nanotube from the liberated feed atoms. Feed atoms disposed over a front side of a substrate are liberated in response to electromagnetic radiation that propagates from the back side of the substrate, through the substrate, to the front side of the substrate. And, from the liberated feed atoms, at least one nanotube is formed over the front side of the substrate in response to at least one catalyst separate from the substrate and disposed over the front side of the substrate and over the feed atoms.

An hBN powder containing an aggregate of primary particles of hBN, the hBN powder having a ratio of an average longer diameter (L.sub.1) to an average thickness (d.sub.1) of the primary particles, [L.sub.1/d.sub.1], of 10 to 25, a tap density of 0.80 g/cm.sup.3 or more, and a BET specific surface area of less than 5.0 m.sup.2/g, in which a particle size distribution curve showing a frequency distribution based on volume of the hBN powder is a bimodal distribution curve having a first peak and a second peak in a range of a particle size of 500 μm or less and having a peak height ratio of a second peak height (H.sub.B) to a first peak height (H.sub.A), [(H.sub.B)/(H.sub.A)], of 0.90 or less, a method for producing the same, and a resin composition and a resin sheet each comprising the hBN powder.

An hBN powder containing an aggregate of primary particles of hBN, the hBN powder having a ratio of an average longer diameter (L.sub.1) to an average thickness (d.sub.1) of the primary particles, [L.sub.1/d.sub.1], of 10 to 25, a tap density of 0.80 g/cm.sup.3 or more, and a BET specific surface area of less than 5.0 m.sup.2/g, in which a particle size distribution curve showing a frequency distribution based on volume of the hBN powder is a bimodal distribution curve having a first peak and a second peak in a range of a particle size of 500 μm or less and having a peak height ratio of a second peak height (H.sub.B) to a first peak height (H.sub.A), [(H.sub.B)/(H.sub.A)], of 0.90 or less, a method for producing the same, and a resin composition and a resin sheet each comprising the hBN powder.