Abstract: A hexagonal boron nitride powder having an average longer diameter (L) of primary particles in the hexagonal boron nitride powder of more than 10.0 ?m and 30.0 ?m or less, an average thickness (D) of the primary particles in the hexagonal boron nitride powder of 1.0 ?m or more, a ratio of the average longer diameter (L) to the average thickness (D), [L/D], of 3.0 or more and 5.0 or less, and a content of primary particles having a ratio of a longer diameter (1) to a thickness (d), [l/d], of 3.0 or more and 5.0 or less of 25% or more, a method for producing the hexagonal boron nitride powder, and a resin composition and a resin sheet each containing the hexagonal boron nitride powder.

Abstract: An hBN powder containing an aggregate of primary particles of hBN, the hBN powder having a ratio of an average longer diameter (L1) to an average thickness (d1) of the primary particles, [L1/d1], of 10 to 25, a tap density of 0.80 g/cm3 or more, and a BET specific surface area of less than 5.0 m2/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 ?m or less and having a peak height ratio of a second peak height (HB) to a first peak height (HA), [(HB)/(HA)], of 0.90 or less, a method for producing the same, and a resin composition and a resin sheet each comprising the hBN powder.

Abstract: An hBN powder containing an aggregate of primary particles of hBN, the hBN powder having a ratio of an average longer diameter (L1) to an average thickness (d1) of the primary particles, [L1/d1], of 10 to 25, a tap density of 0.80 g/cm3 or more, and a BET specific surface area of less than 5.0 m2/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 ?m or less and having a peak height ratio of a second peak height (HB) to a first peak height (HA), [(HB)/(HA)], of 0.90 or less, a method for producing the same, and a resin composition and a resin sheet each comprising the hBN powder.

Abstract: A hexagonal BN powder including aggregates of primary particles of hexagonal BN containing boron and oxygen as impurity elements at a content of 1.00 to 30.00% and 0 to 1.00% by mass, respectively, which has a peak A in a predetermined particle diameter range and a 50% volume cumulative particle diameter D50 (d1) of 30.0 to 200.0 ?l in a particle size distribution curve, and in which a ratio of a height (a1) of the peak A before treatment to a height (a2) of the peak A after treatment is 0.80 to 1.00 and a ratio of D50 (d1) before treatment to D50 (d2) after treatment is 0.80 to 1.00 when the hexagonal BN powder is ultrasonically treated under a predetermined condition for 1 minute. Also disclosed is a method for producing the hexagonal BN powder, a composition and a heat dissipation material.

Abstract: A hexagonal boron nitride (hBN) powder containing an aggregate of primary particles of hBN, in which the powder has a primary particle size of less than 10 ?m, a ratio of an average longer diameter (L1) to an average thickness (d1) of the primary particles, [L1/d1], of 5.0 or more and 20 or less, and a BET specific surface area of less than 10 m2/g. The powder has one maximum peak in a range of a particle size of 45 ?m or more and 150 ?m or less in a particle size distribution curve of a hexagonal boron nitride powder classified to have a particle size of 45 ?m or more and 106 ?m or less, and has a decrease rate of the maximum peak of 10% or more and less than 40%.

Abstract: A hexagonal BN powder including aggregates of primary particles of hexagonal BN containing boron and oxygen as impurity elements at a content of 1.00 to 30.00% and 0 to 1.00% by mass, respectively, which has a peak A in a predetermined particle diameter range and a 50% volume cumulative particle diameter D50 (d1) of 30.0 to 200.0 ?l in a particle size distribution curve, and in which a ratio of a height (a1) of the peak A before treatment to a height (a2) of the peak A after treatment is 0.80 to 1.00 and a ratio of D50 (d1) before treatment to D50 (d2) after treatment is 0.80 to 1.00 when the hexagonal BN powder is ultrasonically treated under a predetermined condition for 1 minute. Also disclosed is a method for producing the hexagonal BN powder, a composition and a heat dissipation material.

Abstract: A hexagonal BN powder containing an aggregate of primary particles of hexagonal BN nitride and having an average primary particle diameter, a 50% volume cumulative particle diameter D50, a BET specific surface area, and a bulk density within predetermined ranges. Further, for a peak A in the particle diameter range of 1.0 ?m or more and less than 20.0 ?m and a peak B in the particle diameter range of 20.0 ?m or more and less than 200.0 ?m in a particle size distribution curve, the ratios of the height of the peaks are within predetermined ranges when the hexagonal BN powder is treated under predetermined conditions. Also disclosed is a method for producing the hexagonal BN powder, a composition including the hexagonal BN powder and at least one of a resin and a rubber, and a heat dissipation material containing the composition.

Abstract: A hexagonal boron nitride powder having an average longer diameter (L) of primary particles in the hexagonal boron nitride powder of more than 10.0 ?m and 30.0 ?m or less, an average thickness (D) of the primary particles in the hexagonal boron nitride powder of 1.0 ?m or more, a ratio of the average longer diameter (L) to the average thickness (D), [L/D], of 3.0 or more and 5.0 or less, and a content of primary particles having a ratio of a longer diameter (1) to a thickness (d), [l/d], of 3.0 or more and 5.0 or less of 25% or more, a method for producing the hexagonal boron nitride powder, and a resin composition and a resin sheet each containing the hexagonal boron nitride powder.

Abstract: An hBN powder containing an aggregate of primary particles of hBN, the hBN powder having a ratio of an average longer diameter (L1) to an average thickness (d1) of the primary particles, [L1/d1], of 10 to 25, a tap density of 0.80 g/cm3 or more, and a BET specific surface area of less than 5.0 m2/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 ?m or less and having a peak height ratio of a second peak height (HB) to a first peak height (HA), [(HB)/(HA)], of 0.90 or less, a method for producing the same, and a resin composition and a resin sheet each comprising the hBN powder.

Abstract: A hexagonal boron nitride powder having an average longer diameter (L) of primary particles in the hexagonal boron nitride powder of 10 ?m or less, an average thickness (D) of the primary particles in the hexagonal boron nitride powder of 0.20 ?m or more, a ratio of the average longer diameter (L) to the average thickness (D), [L/D], of 3.0 or more and 5.0 or less, and a content of primary particles having a ratio of a longer diameter (l) to a thickness (d), [l/d], of 3.0 or more and 5.0 or less of 25% or more. Also disclosed is a method for producing the hexagonal boron nitride powder, and a resin composition and a resin sheet each containing the hexagonal boron nitride powder.

Abstract: A hexagonal boron nitride (hBN) powder containing an aggregate of primary particles of hBN, in which the powder has a primary particle size of less than 10 ?m, a ratio of an average longer diameter (L1) to an average thickness (d1) of the primary particles, [L1/d1], of 5.0 or more and 20 or less, and a BET specific surface area of less than 10 m2/g, and the powder has one maximum peak in a range of a particle size of 45 ?m or more and 150 ?m or less in a particle size distribution curve of a hexagonal boron nitride powder classified to have a particle size of 45 ?m or more and 106 ?m or less, and has a decrease rate of the maximum peak of 10% or more and less than 40% when a dispersion liquid obtained by dispersing the hexagonal boron nitride powder in water is subjected to an ultrasonic treatment for 1 minute, the peak decrease rate being calculated by expression (1), a method for producing the hBN powder, and a resin composition and a resin sheet each containing the hBN powder.