| 摘要 |
PROBLEM TO BE SOLVED: To obtain an inorganic filler that can impart excellent flame retardancy to a polymer material without deterioration of its physical properties and emission of hazardous substance on combustion by surface-coating microfine hollow particles composed of a borax with a polyester resin. SOLUTION: (A) Borax (for example, sodium tetraborate decahydrate) and a foaming agent (for example, an azodicarbonamide) are dissolved in water and the liquid drops of the resultant aqueous solution (A1 ) are heated to effect glassification and foaming thereby preparing microfine hollow particles (preferably the hollow parts in the particles are filled with an inert gas such as nitrogen). Then, the resultant microfine hollow particles are coated on their surfaces with (B) a polyester resin. The objective filler is obtained by spraying the aqueous solution (A1 ) together with an inert gas into an air stream heated at an elevated temperature of 800-1,000 deg.C to heat the liquid drops to form microfine hollow particles, then the particles are coated with the component B on their surfaces in a thickness of 0.5-3μm.
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