Abstract: A stable inorganic pigment having the surface thereof a continuous coating of fine amorphous silica.

Abstract: A process for preparing a stable inorganic pigment coated with a fine amorphous silica which comprises forming a silica sol in an aqueous prepared slurry of an inorganic pigment by reacting an alkali silicate solution with one or more acid gases so that a fine silica sol covers the surfaces of the particles of the inorganic pigment.

Abstract: Novel chlorinated 4-methylphthalic acids or anhydrides of the general formula ##STR1## wherein n is an integer of 1, 2 or 3, with the proviso that when n is 1, the chlorine atom is positioned at 3- or 5-position and when n is 2, the chlorine atoms are positioned at 3- and 5-positions. The new compounds are produced by dissolving 4-methylphthalic anhydride in concentrated sulfuric acid or fuming sulfuric acid to form a solution, and reacting the solution with chlorine at room temperature preferably in the presence of a catalytic amount of iodine, thereby to yield a crude product containing a mixture of chlorinated 4-methylphthalic acids. By subjecting the mixture to a thermal dehydration treatment in an inactive organic solvent, each of the chlorinated compounds may be isolated as its corresponding anhydride in the form of crystals.These chlorinated 4-methylphthalic anhydrides are valuable as intermediates for the preparation of dyestuffs or pigments.

Abstract: An antimony trioxide composition useful as an excellent flame retarding additive comprises antimony trioxide particles coated with hydrous zirconium oxide and amorphous silica.The antimony trioxide composition is prepared by adding an aqueous solution of a zirconium salt to an aqueous slurry of antimony trioxide particles to form zirconium hydroxide therein and to deposit the hydroxide on the surfaces of the antimony trioxide particles, recovering the particles and dehydrating them to form a coating of zirconium hydroxide on the particles, dispersing the hydrous zirconium oxide-coated particles in water, and then adding to the resulting aqueous dispersion a silica sol to deposit amorphous silica on the surfaces of the hydrous zirconium oxide coated antimony trioxide particles.