| 摘要 |
<p>The dyed layer on waste nitrocellulose films is removed by treating the films with an alcoholic solution of an alkali under such conditions as will hydrolyse the surface layer of the film containing the dye. Caustic alkali is preferably used; and the solution may be prepared by dissolving solid caustic soda in alcohol or aqueous alcohol, or adding a concentrated aqueous caustic soda solution thereto. Alternatively the solution may be made by dissolving ammonium, sodium or potassium carbonate, tribasic sodium phosphate, or sodium peroxide in aqueous alcohol. The depth to which hydrolysis proceeds, is determined by adjusting the duration of the treatment or the amount of alkali employed. To ensure removal of the hydrolysed layer, the film may be washed as with warm alcohol and water.</p> |
