A hollow glass microsphere having an average particle size of at most 15 μm based on volume, a maximum particle size of at most 30 μm and an average particle density of from 0.1 to 1.5 g/cm3, which has a glass composition consisting essentially of the following components by mass %: SiO2 50.0-90.0%, Al2O3 10.0-50.0%, B2O3 0-12.0%, Na2O + K2O + Li2O 0-1.0%, CaO 0-10.0%, MgO 0-10.0%, BaO + SrO 0-30.0%.
A hollow glass microsphere is generally called as a glass microbaloon (hollow body), and has low specific gravity, satisfactory heat resistance, heat insulating properties, pressure resistance and impact resistance, and achieves physical property-improving effects in respect of size stability and moldability, as compared with conventional fillers.
Therefore, this is used for lightening uses such as molding parts including a molding compound for electric household appliances, portable electronic devices and automobiles, a putty, a sealing material, a buoyancy material for ships, a synthetic wood, a reinforcing cement outer wall material, a light weight outer wall material, an artificial marble, and the like. Also, due to the structure of hollow particles, hollow glass microspheres have an effect of providing a low dielectric constant, and is a material expected to be used in the field of a multilayer print substrate, an electric wire coating material or the like, which requires a low dielectric constant.