METHOD FOR PREPARING SPHERICAL SILICA POWDER FILLER, POWDER FILLER OBTAINED THEREBY AND APPLICATION THEREOF

摘要

The present invention relates to a method for preparing a spherical silica powder filler. The method comprises the following steps: S1, providing spherical polysiloxane comprising a T unit by means of a hydrolytic decomposition-condensation reaction of R₁SiX₃, wherein R₁ is a hydrogen atom or an independently selectable organic group having carbon atoms 1 to 18, X is a hydrolytic decomposition group, and the T unit is R₁SiO₃-; and S2, under the condition of an oxidizing gas atmosphere having a dew point greater than 10 Celsius degrees under normal pressure, calcining the spherical polysiloxane at a calcination temperature ranged between 650 Celsius degrees and 1,100 Celsius degrees to obtain a low-hardness spherical silica powder filler, the spherical silica powder filler having an uncondensed hydroxyl group. According to the spherical silica powder filler of the present invention, the hardness of silica is reduced without essentially affecting a thermal expansion coefficient of silica.