Abstract: Provided is silica powder that, when used as a resin filler such as a semiconductor sealant, allows for obtaining a resin composition having excellent gap permeability and low viscosity. The silica powder is such that (1) a cumulative 50% mass diameter D50 of a mass-based particle size distribution obtained by a centrifugal sedimentation method is 300 nm to 500 nm (preferably, 330 nm to 400 nm), (2) a loose bulk density is 250 kg/m3 to 400 kg/m3 (preferably, 270 kg/m3 to 350 kg/m3), and (3) {(D90?D50)/D50}×100 is 30% to 45%. In a silica production method in which a silicon compound is burned, silica powder can be produced by installing a burner having a concentric multiple pipe structure of three or more pipes in a reactor which has a cooling jacket portion provided around the burner, and adjusting flame combustion conditions and cooling conditions.

Abstract: Provided is silica powder that, when used as a resin filler such as a semiconductor sealant, allows for obtaining a resin composition having excellent gap permeability and low viscosity. The silica powder is such that (1) a cumulative 50% mass diameter D50 of a mass-based particle size distribution obtained by a centrifugal sedimentation method is 300 nm to 500 nm (preferably, 330 nm to 400 nm), (2) a loose bulk density is 250 kg/m3 to 400 kg/m3 (preferably, 270 kg/m3 to 350 kg/m3), and (3) {(D90?D50)/D50}×100 is 30% to 45%. In a silica production method in which a silicon compound is burned, silica powder can be produced by installing a burner having a concentric multiple pipe structure of three or more pipes in a reactor which has a cooling jacket portion provided around the burner, and adjusting flame combustion conditions and cooling conditions.

Abstract: A three cylinder engine includes a vibration alleviation unit for alleviating vibrations in a vehicle. The vibration alleviation unit is disposed at least one of upon the crankshaft and upon a part that operates in unison with the crankshaft. The three cylinder is supported by engine mounts that are positioned upon at least both ends of the engine in the direction of the crankshaft axis. Given that KV and KH represent spring constants of one of the engine mounts in the pitch and yaw directions of the crankshaft, MV and MH represent components of a primary couple that occurs in the three cylinder engine in the pitch and yaw directions, and MV0 represents the sum of MV and MH, then spring constants of the engine mounts are set such that KV >KH and the vibration alleviation unit is set so as to satisfy the condition 0 <MV/MV0 <0.5.

Abstract: A three cylinder engine includes a vibration alleviation unit for alleviating vibrations in a vehicle. The vibration alleviation unit is disposed at least one of upon the crankshaft and upon a part that operates in unison with the crankshaft. The three cylinder is supported by engine mounts that are positioned upon at least both ends of the engine in the direction of the crankshaft axis. Given that KV and KH represent spring constants of one of the engine mounts in the pitch and yaw directions of the crankshaft, MV and MH represent components of a primary couple that occurs in the three cylinder engine in the pitch and yaw directions, and MV0 represents the sum of MV and MH, then spring constants of the engine mounts are set such that KV>KH and the vibration alleviation unit is set so as to satisfy the condition 0<MV/MV0<0.5.

Abstract: Fine dry silica particles are produced by combustion by using a burner of a multiple-pipe structure, feeding a mixed gas of a gas of a siloxane compound without containing halogen in the molecules thereof and an oxygen gas at a ratio of 0.3 to 1.5 into the center pipe of a burner, and feeding a combustible gas into the first annular pipe on the outer side of the center pipe of the burner. The fine dry silica particles has a BET specific surface area of 20 to 55 m2/g, and wherein the water suspension containing the fine silica particles at a concentration of 1.5% by weight has an optical absorbance ? for the light of a wavelength of 700 nm satisfying the following formula (1): ??240S?1.4?0.07??(1) wherein S is the BET specific surface area (m2/g) of the fine dry silica particles.

Abstract: Fine dry silica particles are produced by combustion by using a burner of a multiple-pipe structure, feeding a mixed gas of a gas of a siloxane compound without containing halogen in the molecules thereof and an oxygen gas at a ratio of 0.3 to 1.5 into the center pipe of a burner, and feeding a combustible gas into the first annular pipe on the outer side of the center pipe of the burner. The fine dry silica particles has a BET specific surface area of 20 to 55 m2/g, and wherein the water suspension containing the fine silica particles at a concentration of 1.5% by weight has an optical absorbance ? for the light of a wavelength of 700 nm satisfying the following formula (1): ??240S?1.4?0.07??(1) wherein S is the BET specific surface area (m2/g) of the fine dry silica particles.

Abstract: This invention provides flame-generated fine silica particles having an average particle size of 0.05 to 1 ?m, wherein a fractal structure parameter ?1 at length scales ranging from 50 nm to 150 nm and a fractal structure parameter ?2 at length scales ranging from 150 nm to 353 nm satisfy the following formulas (1) and (2): ?0.0068S+2.548??1??0.0068S+3.748??(1) ?0.0011S+1.158??2??0.0011S+2.058??(2) wherein S is a BET specific surface area (m2/g) of the fine silica particles, in the measurement of small-angle X-ray scattering. When used as a filler for a semiconductor-encapsulation resin or when used as a filler for a polishing agent or for a coating layer for ink jet papers, the fine silica particles are available at high content without substantial enhancement of the viscosity. Besides, when used as a filler for the resin, the fine silica particles improve the strength of the molding compound.

Abstract: This invention provides flame-generated fine silica particles having an average particle size of 0.05 to 1 ?m, wherein a fractal structure parameter ?1 at length scales ranging from 50 nm to 150 nm and a fractal structure parameter ?2 at length scales ranging from 150 nm to 353 nm satisfy the following formulas (1) and (2): ?0.0068S+2.548??1??0.0068S+3.748??(1) ?0.0011S+1.158??2??0.0011S+2.058??(2) wherein S is a BET specific surface area (m2/g) of the fine silica particles, in the measurement of small-angle X-ray scattering. When used as a filler for a semiconductor-encapsulation resin or when used as a filler for a polishing agent or for a coating layer for ink jet papers, the fine silica particles are available at high content without substantial enhancement of the viscosity. Besides, when used as a filler for the resin, the fine silica particles improve the strength of the molding compound.