| 摘要 |
The process of the parent Specification for bleaching and freeing from lignin constituents bast fibres, especially flax, hemp and the like is modified in that the bowking [stage (1)] is replaced by soaking for some hours in a warm sodium carbonate solution containing, if desired, caustic alkali, and in that the acidity of the hypochlorous acid bath [stage (2)] is adjusted to a pH value <4,5. Thus stage (1) may comprise a soaking overnight in a solution containing 2 to 9 grams of sodium carbonate per litre at 40-90 DEG C. The quarterto half-bleached goods may be further bleached to a full white, e.g. by infusion with dilute sodium carbonate solution followed by hanging out for a few days or by a weak peroxide and/or hypochlorite bleach. |
