Disclosed herein are processes for purifying as-synthesized boron nitride nanotube (BNNT) material to remove impurities of boron, amorphous boron nitride (a-BN), hexagonal boron nitride (h-BN) nanocages, h-BN nanosheets, and carbon-containing compounds. The processes include heating the BNNT materials at different temperatures in the presence of inert gas and a hydrogen feedstock or in the presence of oxygen.

Provided is a boron nitride agglomerate. The boron nitride agglomerate is of a multi-stage structure formed by arranging flaky hexagonal boron nitride primary particles in three-dimensional directions through adhesion of an inorganic binder. Further provided is a method for preparing the boron nitride agglomerate. The method comprises: mixing flaky hexagonal boron nitride primary particles with an inorganic binder, and controlling the mass of the inorganic binder to account for 0.02-20% of the mass of the flaky hexagonal boron nitride primary particles, so as to obtain the boron nitride agglomerate. The boron nitride agglomerate provided can be added to thermosetting resin compositions, and resin sheets, resin composite metal foil, prepregs, laminates, metal foil-covered laminates, and printed wiring boards prepared using the same have higher boron nitride addition, high thermal conductivity, and high peel strength.

The present invention provides boron nitride particles that can be used for preparation of a thermally conductive material having excellent thermally conductive properties and peel strength. In addition, the present invention provides a composition for forming a thermally conductive material, a thermally conductive material, a thermally conductive sheet, and a device with a thermally conductive layer, in relation to the boron nitride particles. In the boron nitride particles of the present invention, an atomic concentration ratio of oxygen atomic concentration to boron atomic concentration on a surface, detected by X-ray photoelectron spectroscopy, is 0.12 or greater, and a D value obtained by Equation (1) is 0.010 or less.

D value=B(OH).sub.3(002)/BN(002)  Equation (1) B(OH).sub.3(002): Peak strength derived from a (002) plane of boron hydroxide having a triclinic space group measured by X-ray diffraction BN(002): Peak strength derived from the (002) plane of boron nitride having a hexagonal space group measured by X-ray diffraction.

Disclosed are methods for forming boron nitride-containing aggregates that exhibit improved wear by attrition, and resulting filled polymers that exhibit significantly improved thermal conductivity. The boron nitride-containing aggregates are prepared according to a method that includes wet granulating boron nitride powder with a granulation solution to form wet boron nitride-containing granules; and drying the wet boron nitride-containing granules to cause evaporation of solvent in the granulation solution, thereby forming boron nitride-containing granules. Sintering achieves the desired boron nitride-containing aggregates.

Aligned high quality boron nitride nanotubes (BNNTs) can be incorporated into groups and bundles and placed in electronic and electrical components (ECs) to enhance the heat removal and diminish the heat production. High quality BNNTs are excellent conductors of heat at the nano scale. High quality BNNTs are electrically insulating and can reduce dielectric heating. The BNNTs composite well with a broad range of ceramics, metals, polymers, epoxies and thermal greases thereby providing great flexibility in the design of ECs with improved thermal management. Controlling the alignment of the BNNTs both with respect to each other and the surfaces and layers of the ECs provides the preferred embodiments for ECs.

The problem to be solved is to provide a boron nitride particle stably and efficiently with a high organic modification ratio.

To solve the problem, the continuous production method according to the present invention comprises contacting step for continuously supplying a boron nitride with pretreatment and an organic modifier to continuously contact them with an aqueous material in a subcritical state in a presence of an acid or a base. The pretreatment comprises any one or more kinds selected from adding an acid to the boron nitride, adding a base to the boron nitride, adding an oxidant to the boron nitride, adding a reductant to the boron nitride, and conducting a hydrothermal treatment or a solvothermal treatment to the boron nitride.

Disclosed are methods for forming boron nitride-containing aggregates that exhibit improved wear by attrition, and resulting filled polymers that exhibit significantly improved thermal conductivity. The boron nitride-containing aggregates are prepared according to a method that includes wet granulating boron nitride powder with a granulation solution to form wet boron nitride-containing granules; and drying the wet boron nitride-containing granules to cause evaporation of solvent in the granulation solution, thereby forming boron nitride-containing granules. Sintering achieves the desired boron nitride-containing aggregates.

To provide a composition for a three-dimensional integrated circuit capable of forming a filling interlayer excellent in thermal conductivity also in a thickness direction, using agglomerated boron nitride particles excellent in the isotropy of thermal conductivity, disintegration resistance and kneading property with a resin. A composition for a three-dimensional integrated circuit, comprising agglomerated boron nitride particles which have a specific surface area of at least 10 m.sup.2/g, the surface of which is constituted by boron nitride primary particles having an average particle size of at least 0.05 μm and at most 1 μm, and which are spherical, and a resin (A) having a melt viscosity at 120° C. of at most 100 Pa.Math.s.

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.

The present disclosure relates to hexagonal boron nitride nanosheet/ceramic nanocomposite powder including surface-modified hexagonal boron nitride nanosheets which serve as a reinforcing agent for the matrix ceramic, and a method for producing the same, and a hexagonal boron nitride nanosheet/ceramic nanocomposite material including the hexagonal boron nitride nanosheet/ceramic nanocomposite powder and a method for producing the same.