Preparation method of gasket with low specific gravity and high thermal conductivity

The invention provides a preparation method of a low-specific-gravity high-thermal-conductivity gasket, which is characterized in that modified spherical graphite is used as a main thermal-conductivity filler, so that the specific gravity of the thermal-conductivity gasket is effectively reduced while the thermal conductivity is improved. The modification treatment process of the spherical graphite comprises the following steps: (1) preparing a suspension; (2) precipitating and coating; (3) heat treatment of the powder; and (4) surface treatment. Spherical graphite is subjected to aluminum oxide precipitation coating, then a silane coupling agent is used for carrying out surface treatment on powder, the compatibility of the spherical graphite and a polymer matrix is improved, the limit filling amount of the spherical graphite is increased, and therefore the heat conductivity of the prepared gasket is improved; and the surface of the spherical graphite covers an insulating inorganic matter interface, so that t