Dry-process fine silica particle

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 m 2 / 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): wherein S is the BET specific surface area (m 2 / g) of the fine dry silica particles. 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.

Description

technical field [0001] The present invention relates to novel dry silica fine particles suitable for use as fillers for resin compositions used in semiconductor encapsulating materials, liquid crystal sealing materials, laminated substrate insulating materials, etc., or external additives for toners for electrophotography. Background technique [0002] In recent years, with the high integration and high speed of semiconductor elements, there is a tendency for the heat dissipation of semiconductor elements to increase, and there is thermal expansion of semiconductor elements and packaging materials or circuit boards (especially laminated substrates) on which semiconductor elements are mounted. The probability of occurrence of defects due to inconsistency tends to increase. Therefore, it is necessary to increase the amount of filler added to a resin for semiconductor encapsulation or a resin for forming an insulating layer of a laminated substrate. This is because by adding a...

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Problems solved by technology

As a result, there was a problem that the reliability of the machine to which the resin composition was applied was lowered due to poor gap permeability, clogging between wirings, and the like in a resin composition to which such spherical silica was added.

[0022] In the case of the sol-gel method of (1), since so-called monodisperse particles can be obtained, it is easy to control the particle size and particle size distribution, but there is a problem as follows: In the drying and firing stage, the particles are firmly aggregated to produce coarse particles

Therefore, in the classification of the above-mentioned silica particles, it is necessary to pass wet classification methods such as wet sieving and water sieving classification. If this method is adopted, a drying process for the particles is required, and the particles are firmly aggregated during drying, which instead produces coarse particles. Particles, it turns out that for silica microparticles the particle size distribution cannot be controlled by classification

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