Study On The Optimum Discoloring Condition And Spinnability Of Yakwool

In recent years, as a kind of rare and fine animal fiber, yakwool has got more and more attention from the textile industry. According to the color classification, the main colors of yakwool are black and taupe, just a little proportion is white. Due to it, dark yak fibers usually need to be discolored before developing some light color products. Because their natural colors limit further applications. Nowadays, although colored animal fibers are discolored through different processes, substantial damage for fiber is still unavoidable and the other properties of fiber, like spinnability and dyeability would also be influenced by it. Therefore, in view of fiber discoloring effect, it becomes more critical to find optimum discoloring condition.This paper mainly focused on some researches about yakwool discoloring process and discolored yakwool spinnability. Firstly, the properties of yakwool, like the morphologies of cross section and longitudinal section, the strength and elongation property, the crimp property and so on were tested and comparatively analyzed with cashmere and camel hair. Moreover, the structure of extracted melanin granules were analyzed through SEM and on the basis of it, the mordanting, oxidization and reduction discoloring process was selected. And then, important parameters were selected and analyzed through single factor optimization tests. According to the changing trends and optimized areas got by the single factor optimization tests, multi-factors orthogonal tests were done separately during the mordanting and oxidization process, which aimed to ensure fiber whiteness and reduce fiber damage. Finally, 25 tex and 16.7tex discolored yarns spun under optimum spinning process were studied, which were based on the analysis of discolored fiber properties and reasonable spinning technologies. And then, better spinning parameters combinations were got, which could be used to lay the foundation of similar products development.The result shows that:(1) Comparing with cashmere and camel fiber, the scales of yak fibers arrange densest and it is shortest and thickest. Besides, the crimp properties of yak fibers are neither too good nor too bad and there is no big difference between the structure groups.(2) Yakwool melanin granules represent round or oval, the width of signal melanin granule is about 500 nm and its length is between 480 nm and 1100 nm. As for its internal structures, there are several groups like-NH-?-OH- or COO- exist.(3) Through single factor optimization and multi-factors orthogonal tests, the optimum mordanting condition is ferrous ions concentration 12g/L, sodium bisulfite concentration 1g/L, temperature 60?, time 30 min and pH value of the solution 3. The optimum oxidation discoloring process is hydrogen peroxide concentration 25g/L, sodium pyrophosphate concentration 5g/L, temperature 75?, time 90 min and PH value of the solution 8.5. Moreover, the discolored fibers meet the spinning requirement.(4) Comparing with untreated yakwool, discolored yak fibers become shorter and thinner, the scales damaged, the physical and mechanical properties decreased. Therefore, during the fore-spinning process, more oleine oil should be added in moderation, and some technological principles such as soft carding, low speed, light quantitative and small gauge also need to be followed. During the spinning process, the twists of discolored yakwool yarns should be improved about 3-5%, and the spinning speed should also decrease.