| abstract |
Microspheric opacifying agents are provided by admixing an aqueous, partially condensed, aldehyde condensation product with an oily material containing an emulsifying agent thereby forming a water-in-oil emulsion, admixing an amphiphilic acid catalyst with the emulsion and polymerizing the condensation product to form discrete, substantially spherical, opaque, solid particles. Additionally, the solid particles may be separated from the oily continuous phase and admixed with water for the further removal of oil material, and thereby causing the formation of spherical agglomerates or "super particles" having a substantially greater opacity than the aforesaid discrete particles. The super particles are hollow, substantially spherical particles having substantially spherical, discontinuous walls composed of agglomerated substantially spherical particles. |