Hydrophobic free-flowing build=up granules for coating ceramics etc. - contain hydrophilic inorganic powders, hydrophobic poly-organo:siloxane] and opt. temporary and/or permanent binder

摘要

Hydrophobic, free-flowing build-up granules with mean grain size 5-150 microns (I) are based on one or pref. several hydrophilic, inorganic powders with mean particle size 0-30 microns (II) and contg. 0.03-15 (pref. 0.05-3) wt.% hydrophobic polyorganosiloxane(s) (III) and opt. up to 15 wt.% temporary and/or permanent binder(s) (IV). Prodn. of (I) comprises mixing (II) with 0.05-15 (pref. 0.5-3) wt.% (III) in a granulator, opt. with addn. of up to 15 wt.% (IV) in aq. medium and then tempering the prod. for up to 24 hrs. at 120-600 (pref. 200-400) deg.C. (II) are raw materials for glazes, or frits, glasses, pigments, inorganic colours, metals, metal alloys, metal oxides, nitrides, carbides, sulphides and/or borides. Pref., (II) is, e.g. clay, kaolin, Al oxide, wollastonite, dolomite, CaCO3, ZnO, Zr silicate, TiO2, Fe oxide, ZrO2, Si3N, SiC, B4C, WC, AlN etc., or a complex frit (e.g. see below) or an oxynitride or oxycarbide glass. (III) is e.g. trimethylsilyl-polydimethylsiloxane, opt. contg. methylphenyl- or diphenyl-siloxy gps.. (IV) is a temporary organic binder such as starch glue, CMC, PVAC or other polymer adhesive, or a permanent inorganic binder such as Na silicate, AlPO4, CrPO4, Na aluminate, Al silicate, silica sol, etc.. USE/ADVANTAGE - Used for the electrostatic powder coating of substrates, esp. ceramic substrates, for the prodn. of ceramic layers by dry coating, esp. by sifting, sprinkling or spraying, for incorporating into ceramic layers or hydrophibic media such as plastics or paints, and for the prodn. of enamel layers (enamelling) (claimed). (I) are hydrophobic, free-flowing granules suitable for electrostatic powder coating, with high electrical resistance, contg. inorganic powders with different particle size distributions, different density and/or different resistance; granules (I) show no tendency to sepn. and can even be recycled.