Investigation And Application Of Micro-suspension Low-temperature Dyeing Technology For Woolen Reactive Dyes

The conventional dyeing for wool top was commonly conducted at boiling temperature. Therefore wool damage and negative effect on its original properties were unavoidable. And these are negative factors affect the spinning performance of wool fiber and properties of its product. In this investigation, the self-made low-temperature dyeing agent XPND(short for XPND) was used as the main dyeing auxiliary based on the micro-suspension dyeing(short for MSD) technology. And a production-study-research investigation method was taken through the combination of mechanism investigation, sample dyeing experiment and production. The purposes of micro-suspension low-temperature dyeing(short for MSD low-temperature dyeing) of wool with woolen reactive dyes, reducing wool damage, improving the spinning performance of wool fiber and properties of its product were reached.A series of Lanasol and Lanasol-CE reactive dyestuffs were selected and applied in this investigation. During the dyeing process, dye-auxiliary aggregations with certain particle size were formed in the dye bath through the stirring of micro-suspension low temperature dyeing agent XPND with reactive dyestuffs at certain conditions. And the surface tension of the dye bath was significantly reduced, while the affinity between the dye-auxiliary aggregations and fiber was increased. Therefore, the adsorption speed of the dye-auxiliary aggregations with fiber was accelerated under the circulation of dyeing liquid. Meanwhile, as the MSD low-temperature dyeing agent XPND possesses good wetting and swelling properties to the fiber, it will have positive effect on the diffusion of dyes from the fiber surface to internal fiber. Thus resulting to the realization of low-temperature dyeing. The single factor variable method was used in this investigation and the optimum process parameters of the micro-suspension low temperature dyeing was set as follow: when the dye dosage was no more than 4%(owf), the glacial acetic acid dosage was 2.0%(owf)、XPND 2.0%(owf)、under 90℃ dyeing for 90min; when the dye dosage was no less than 4%(owf), the formic acid dosage was 2.0%(owf)、XPND 2.0%(owf)、under 90℃ dyeing for 90 min.The investigation of the mechanism of micro-suspension low temperature dyeing shown that:(1) Through the testing of particle size and surface tension of dyeing liquid show that the micro-suspension effect of low temperature dyeing auxiliary XPND with the dyestuffs has changed existence state of dyestuffs in the dye bath, and dye-auxiliary aggregations were formed, and the surface tension of dyeing liquid was reduced.(2) Through the research on dyeing thermodynamics suggests that compared with the conventional dyeing process, the dye adsorption isotherm types of MSD low-temperature dyeing process is not changed, and it is still the Langmuir type.(3) The investigation of dyeing dynamics research shows that when compared with conventional dyeing process, the dyeing rate constant and diffusion coefficient of the MSD low-temperature dyeing process is higher, and the half dyeing time is shorter. Therefore, the adsorption speed of the dye with fiber and diffusion of dyes from the fiber surface to internal fiber were accelerated, resulting to the realization of low-temperature dyeing.The production results of MSD low-temperature dyeing shown:(1) The color accuracy can be guaranteed and the color fastness is good, fiber damage was reduced and the dyed fiber possesses the handle characteristic of fluffy、smooth and fine elasticity.(2) Compared with the conventional dyeing results, times of wool top blocking roller during gilling procedure was decreased significantly, fud rate was reduced, and the uniformity of the roving evenness was improved. The spinning performance was highly improved with the end-breaking rate of yarn(55/2) was reduced 19.3%, the mechanism efficiency of cutting defects of yarns was improved 3.90%, the yarn made rate was improved 0.67%, meanwhile, the same production effect of yarn(55/1) and yarn(88/2) was obatained.(3) Compared with conventional dyed product, color changes after finishing of MSD low-temperature dyed product was significantly reduced.(4) The properties of the final product are excellent, the quality of the product was improved, and it can satisfy the production and market requirements.The MSD low-temperature dyeing new technology possesses the characteristic of reducing wool damage, improving the fiber spinning performance, increasing production efficiency, and improving the inner quality of fabric. However, it has important practical value.