Manufacturing process for hollow microspheres
AssigneePQ Corporation
InventorBruce W. Sands
Life of this patent
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Abstract
More perfect, less porous hollow microspheres can be prepared by spray-drying dispersions of film-forming solids that contain certain organic solvents. The organic solvents are water-miscible and have boiling points of 100.degree. C. or more. The solvent is added just prior to spray drying and the resulting product has fewer cracks and/or holes. This improvement is especially beneficial to preparation systems involving alkali metal silicates and "polysalts."
Claims6
In the process of preparing hollow microspheres by spray drying an aqueous dispersion of film-forming substance and recovering the product the improvement consisting of adding a porosity reducing amount of a water miscible organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100.degree. C. prior to spray drying.
In the process of preparing hollow microspheres by spray drying a solution of alkali metal silicate and a "polysalt" recovering the spray dryer product and further drying, the improvement consisting of adding a porosity-reducing amount of a water-miscible, alkali-stable organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100.degree. C. prior to spray drying.
In the process of preparing hollow microspheres by spray drying a solution selected from the group consisting of sodium silicate and ammonium pentaborate, sodium pentaborate and sodium hexametaphosphate, recovering the spray dryer product and further drying, the improvement consisting of adding a porosity-reducing amount of a water-imiscible, alkali-stable, silicate-compatible organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100.degree. C. prior to spray drying.
Dependencies are inferred from the claim text.