Tokuyama Corporation

Hiroo Aoki

Masakazu Ohara

Yukihiro Takata

Masahide Ueda

Minoru Kimura

Keiji Saiki

Masayuki Numata

Teppei Ueno

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 Dof 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/mto 400 kg/m(preferably, 270 kg/mto 350 kg/m), and (3) {(D−D)/D}×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.

Silica powder, resin composition, and dispersion

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 m/g, and wherein the water suspension containing the fine silica particles at a concentration of 1.5% by weight has an optical absorbance &#x3c4; for the light of a wavelength of 700 nm satisfying the following formula (1):&#x3c4;&#x2266;240S&#x2003;&#x2003;(1) The fine dry silica particles do not almost contain coarse particles or aggregated particles, have a sharpe grain size distribution, excellently disperse in the resins, suppress a rise in the viscosity when highly filled, and impart sufficiently large strength to the resin compound.

Fine dry silica particles

This invention provides flame-generated fine silica particles having an average particle size of 0.05 to 1 &#x3bc;m, wherein a fractal structure parameter &#x3b1;at length scales ranging from 50 nm to 150 nm and a fractal structure parameter &#x3b1;at length scales ranging from 150 nm to 353 nm satisfy the following formulas (1) and (2):&#x2212;0.0068+2.548&#x2266;&#x3b1;&#x2266;&#x2212;0.0068+3.748&#x2003;&#x2003;(1)&#x2212;0.0011+1.158&#x2266;&#x3b1;&#x2266;&#x2212;0.0011+2.058&#x2003;&#x2003;(2)

Fine silica particles having specific fractal structure parameter

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Shunan, Japan

Hiroo Aoki