Application Of Low Temperature Dyeing Agent And Strength Improver For Wool

Dyeing wool fiber products is generally carried out at a boiling temperature. Thus, various disadvantages such as yellowing, strength loss of protein fiber, and the like are generated, which produce unfavorable effects on the spin ability of the fiber. What's more, the conventional protein fiber dyeing technique is not necessarily optimum in view of low energy cost. In order to solve these problems, there have been investigated many methods, of which the two most widely used are dyeing wool at a boiling temperature with protective agents and the low-temperature dyeing method.With the increasing attention to the issues of environmental protection and energy, the industries were required to find environmentally favorable alternatives in dyeing and finishing processes. The development of low-temperature dyeing method of wool is an important reflection of this tendency. However, dyeing wool at low temperature with the existing agents has not yet been practically used by the reasons as mentioned below. That is, not all kinds of dyes are appropriate for low-temperature dyeing. Also dyeing fastness of the resulting dyed material is likely low and permeation of a dye is insufficient, and uniform dyeing is impaired since the dyeing and fixation are too fast. As a result, this method is only limited to some dyes and light shade.The object of this paper is to provide a low-temperature dyeing additive for wool, so that the fiber could be dyed at lower temperature and shorter time with satisfied dyeing performance and low energy cost. We also developed a strength improver in order to enhance the strength of the dyed wool.Low temperature dyeing of wool with a self-made agent and two other auxiliaries has been carried out at 85℃. The dosage of the agent on the dye pickup was studied and 1.0g/L was recommended. Dyeing performance such as dye pickup, color fastness and permeation of a dye was compared with conventional dyeing. The results showed that the saturation dye exhaustion of acid dyes dyed at low temperature was above 95%, and the color fastness was basically at the same level with those dyed at the boil. The low temperature dyeing using author-made agent markedly diminished wool fiber damage, from 17.32% at boiling temperature to 7.26%, and warp and weft direction tearing strength damage of wool fabric decreased from 36.58% to 10.14% and 24.01% to 10.99% respectively, compared to those dyed at boiling. The self-made agent is adaptable to different dyes, and its overall performance is better than two other auxiliaries studied in the paper.In order to enhance the strength of dyed wool, water-based polyurethane was used as a finishing agent. Fiber strength and tearing strength of fabric was tested. The result indicated that different structure of polyurethane had a different impact, only the one that was prepared from PEG-1500 and the chain extender was composed of amine-group compound, silicane compound and small molecule compound with a number of hydroxyl groups could enhance the strength, of which the molecular weight of silicane compound was 850, and 60% of hydroxyl groups of the hydroxyl compound were substitute by silicane compound has the best effect. We defined it as the strength improver for wool.The dosage of the agent on the tearing strength was studied and 10% (o.w.f.) was recommended by the finishing process of steeping as well as 9g/L by pad-baking. Strength of wool fiber dyed with acid dyes increased 18.92%, and warp direction tearing strength of wool fabric increased 10.41%. Fiber strength rose by 16.33% and 7.37% respectively when it came to the wool dyed with metal complex acid dyes. Treated with strength improver resulted in no side effects on the color fastnesses except the dry rubbing fastnesses of some dyes. Both frictional coefficients with scales and against scales of wool decreased.