Phosphor manufacturing with fine and coarse Si02 particles

摘要

Fluorescent screen has a phosphor layer containing a phosphor composition made of a phosphor with a coating layer with one or more oxygen compounds of Zn, Al, Mg, Ca and Ba and colloidal SiO2 particles. The movelty is that the colloidal SiO2 particles consist of SiO2 particles with an average particle size 4nm at most d at most 30 nm corresponding to a specific surface area of 100 m2/g at most A(s) at most 550 m2/g and SiO2 particles with an average particle size 50 nm at most d at most 150 nm. Corresponding to a specific surface area of 25 m2/g at most A(s) at most 70 m2/g. Production of the phosphor composition is also claimed. A phosphor slurry is adjusted to at least 9.2 pH with diluted NH3 and then ground with SiO2 particles with a particle size nm4 at most 30 nm. A colloidal solution of colloidal SiO2 particles with a particle size 50 nm at most d at most 150 nm is added to the slurry, followed by an aqueous NH4 salt solution and then an aqueous solution of a water-soluble salt of Zn, Al, Mg, Ca or Ba. The pH of the phosphor slurry is reduced to at most 7 using dilute acid and then raised to at least 8. The coating layer contains 0.01-0.07 wt.% colloidal SiO2 particles of average particle size 4 nm at most d at most 30 nm, and 0.10-1.5 wt.% colloidal SiO2 particles of average particle size 50 nm at most d at most 150 nm. The oxygen compound is a Zn-O compound. The coating layer contains a colour filter pigment.