| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for dyeing in deep blue color and an apparatus suitable for the process capable of properly dyeing even the inner part of a thick dyeing object and continuously and quantitatively controllable with a single vessel. SOLUTION: Indigo is converted into leucoindigo with a reducing agent and an alkali, an aqueous solution 15 of the leucoindigo is charged into a vessel 8, a dyeing object is immersed in the solution to effect the impregnation of the leucoindigo and repeatedly lifted from the aqueous solution 15 in the vessel 8 into the air above the solution in the vessel to return the leuco compound to indigo, the above operation is repeated, an acid is added to the aqueous solution 15 to convert the leucoindigo in the aqueous solution 15 into indigo vat acid, the dyeing object is immersed in the mixed liquid in the vessel 8 to apply the indigo vat acid to the surface of the dyeing object, the object is lifted into air in the vessel to oxidize the attached indigo vat acid to indigo and the above procedure is repeated. Finally, the dyeing object is dehydrated and dried in the vessel 8 or after taking out of the vessel 8.
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