Phosphate → Zinc Phosphate

Participants

Reaction Steps

For example, when the phosphor is coated with Zn3 (PO4)2, the following method can be employed. To a prescribed amount of phosphor, an aqueous phosphate solution necessary for the surface treatment previously determined is added and the resulting suspended mixture is warmed to about 30° to about 60° C. with stirring for several tens minutes. Subsequently an aqueous solution of a zinc salt containing zinc ions in stoichiometrically equivalent amount or 2 to 3 times in excess comparing with the amount of the phosphate group in the mixture is added to the mixture and the pH of the system is adjusted to about 4 to 9 with stirring for several minutes and thereafter the resulting mixture is allowed to stand for about 1 hour. Thus the phosphor substantially coated with zinc phosphate can be obtained. The thus coated phosphor is taken out of the water, washed with water and dried to give a surface treated phosphor. As the aqueous solution of phosphate salt, it is preferable to use an about 10% aqueous solution of phosphoric acid, or water soluble sodium or potassium phosphate, either monobasic, dibasic or tribasic. As the aqueous solution of a zinc salt, it is preferable to use an about 10% aqueous solution of zinc sulfate, zinc nitrate, and the like.

Provenance & Evidence