| 摘要 |
PURPOSE:To prevent oxidation by a dichromate during heat treatment, to prevent lowering in luminous brightness and to prevent an ultramarine blue pigment from being faded, by introducing a step of reducing a dichromate into a step of regenerating a phosphor having a dichromate deposited thereon. CONSTITUTION:In regenerating a blue light emitting phosphor having an ultramarine blue pigment contg. a dichromate, which is recovered in a fluorescent screen forming step in the production of a picture tube, washing with warm pure water is conducted first by decantation. An org. reducing material selected from the group consisting of hydroxylamine hydrochloride, oxalic acid and ascorbic acid or an inorg. reducing material such as hydrogen sulfide is added to the phosphor slurry to reduce the dichromate deposited on the phosphor to a chromium trioxide which is chemically and thermally stable. The phosphor is washed with warm water by decantation, recovered by filtration, dried and heat-treated to obtain a regenerated phosphor.
|
