Abstract:
This application discloses triorganic phosphate coating compositions for viscous-impingement air filters in which the triorganic phosphate is thickened by a combination of about 0.1 to 1.0 parts of a magnesium silicate, with at least 10 percent of its particles which are less than 1 micron in any dimension and whose silica to magnesia ratio is about 1.05 to about 1.30 to 1, and 0.1 to 3 parts of pyrogenic silica having a particle size no greater than 0.025 microns. These gel compositions have good high-temperature viscosity stability and exhibit low syneresis losses. Satisfactory gels can be prepared using as little as one percent pyrogenic silica with 0.5 percent of the magnesium silicate.
Abstract:
THERMALLY STABLE TRIORGANIC PHOSPHATE COATING COMPOSITIONS FOR VISCOUS-IMPINGEMENT AIR FILTERS ARE PREPARED BY THICKENING 100 PARTS OF A TRIORGANIC PHOSPHATE WITH A COMBINATION OF 0.5 TO 5 PARTS OF A PURE PYROGENIC SILICA WITH 0.5 TO 7 PARTS BY WEIGHT OF A HYDRATED SALT, ALUMINUM DISTEARATE OR SYNTHETIC CALCIUM SILCATE.