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Novel pigments useful as primary extenders in exterior grade latex formulations are described. The pigments are composed of particles of calcined clay, substantially all the particles of which are finer than about 44 microns and having an average particle size, equivalent spherical diameter, within

Novel pigments useful as primary extenders in exterior grade latex formulations are described. The pigments are composed of particles of calcined clay, substantially all the particles of which are finer than about 44 microns and having an average particle size, equivalent spherical diameter, within the range of about 3 to 10 microns, most preferably within the range of about 4 to 8 microns. The novel pigments are further characterized by having a significantly lower oil absorption value (ASTM) than conventional, calcined clay pigments. Exterior grade paint formulations containing such pigments can be formulated below the critical pigment volume concentration without substantially reducing opacity or chalking resistance.

대표청구항 ▼

A process for producing a calcined kaolin clay pigment which comprises: (a) fractionating a hydrous clay to obtain a fine fraction having an average particle size less than about 1 micron, e.s.d., and fractionating the same or a different hydrous clay to obtain a coarse fraction having an average pa

A process for producing a calcined kaolin clay pigment which comprises: (a) fractionating a hydrous clay to obtain a fine fraction having an average particle size less than about 1 micron, e.s.d., and fractionating the same or a different hydrous clay to obtain a coarse fraction having an average particle size above about 3 microns, e.s.d., (b) blending said fine fraction and said coarse fraction of clay such that the resulting blend has an average particle size in the range of about 3 to 10 microns, e.s.d., (c) calcining said blended clay under conditions of time and temperature such that said hydrous kaolin clay is substantially dehydrated by passing through the characteristic kaolin endotherm, and (d) milling said calcined blended clay without reducing average particle size below about 3 microns, e.s.d. until an oil absorption below about 35 g. oil/100 g. clay as determined by ASTM spatula rubout is achieved.