Study On The One Step Extracting-dyeing Technology With Natural Dyes In Supercritical CO₂

The fine performance of supercfitical CO₂ on dissolution and diffusion make it substitutefor water as dyeing medium. As a result of its characteristic such as the conservation of energyand water and the short technical process, the research of supercritical CO₂ dyeing technologyhas become a hot spot in domestic and foreign dyeing and finishing industry. Currently, theresearch of supereritical CO₂ dyeing technology was restricted in the application stage ofchemical dyestuffs. Kinds of finishing methods have to be utilized to make natural fibersachieve the good dyeing effect, by dint of the improvement of compatibility between dyestuffsand fibers. However, the negative influence of this kind of research is: on the one hand,finishing increases the costs; the other, supercfitical dyeing process is originally green, butpollution may be caused by finishing. To the development of "eco-green" technology withnon-pollution and low-energy-consumption, the curcuma is adopted as dye in this paper, and theone step extracting-dyeing technology has been carried out in supercritical CO₂ dyeinginstrument.The nature, thermodynamic principles and mass transfer mechanism of the supercfiticalCO₂ are elaborated. The one step extracting-dyeing technology in supercritical CO₂ has beenproposed. The shrinking core model of natural curcuma is established. The crystal structure andbinding characteristic with natural fibers of natural curcumin are analyzed from the molecularlevel. The curcumin obtains good performance of solubility and dispersibility in supercriticalCO₂, because its molecule size and molecule polarity is both small. Therefore the one stepextracting-dyeing technology has been achieved.The the one step extracting-dyeing technology in supercritical CO₂ experiments aredesigned and implemented on natural fiber fabrics and chemical fiber fabrics throughorthogonal experiments and single factor experiments. The optimal dyeing parameters havebeen determined by the study of the influence of supercfitical CO₂ extracting-dyeing craft ondyeing-color eigenvalues. The results indicate that, in extracting-dyeing one-stage craft, theparticle size of eurcuma is an important influencing factor. The chromatic aberration, hue and fixing rate increased along with the reducing of particle size of curcuma. The maximum valuesof the chromatic aberration and fixing rate are obtained when the particle size of curcuma is0.5mm. The level dyeing property is improved and the dyeing time is reduced by applying theassociative craft of inside dyeing and outside dyeing. The dyeing effect of chemical fibers isbetter than that of protein fibers and cellulose fibers, and the dyeing form of winding fabricsurpasses that of stacking. The optimal dyeing craft for wool fabric is as follows: the diameterof the curcuma particle is 0.5mm, the pressure is 27MPa, the temperature is 80℃and thedyeing time is 50min. The optimal dying craft for cotton fabric is that 0.5mm, 27MPa, 100℃and 50min. The optimal dying craft for PET fabric is that 0.5mm, 27MPa, 80℃and 50min.The the one step extracting-dyeing technology in supercfitical CO₂ has many superiorcharacteristic, such as short dyeing time and excellent levelness and color fastness. Therationale has been provided for applying the natural dyestuff to the supercritical CO₂ dyeingcraft technology research.