Application Of Ionic Liquids In Supercritical Carbon Dioxide Dyeing

In recent years, the situation of water resources of China is not optimistic, a new environmental protection technology which is capable of solving the problem of water pollution or realizing the waterless dyeing has a great application prospect; Supercritical carbon dioxide dyeing with shorter dyeing time and better levelness and penetration compared with the traditional dyeing process is a new dyeing technology, without reduction cleaning after dyeing nor polluting the environment, it has solved many problems in the traditional dyeing process such as the great water resources consumption, serious environmental pollution and difficulty in industrial application. Currently, people have achieved some success in supercritical dyeing at home and abroad, but because of the stable structure, high degree of crystallinity and orientation of hemp fiber molecular which affect the dyeing effect, textile workers have been working on this.Ionic liquids composed of organic positive cations containing nitrogen, phosphorus and large inorganic negative ions is a salt compound which is liquid form at or near room temperature. It has many excellent properties compared with traditional solvent such as strong polarity, not volatile, not easy to be oxidation. As a green solvent, ionic liquids can destroy the original hydrogen bonding of fiber intermolecular and intermolecular through local swelling on fiber crystalline regions and fiber surface dissolution, increasing the affinity between the fiber and the dye, and the dyeing effect is improved.In this experiment, kenaf fiber is pretreated with 1- butyl-3-methyl imidazole chloride ionic liquid, then the treated kenaf is waterless dyed in supercritical carbon dioxide state. Analyzed influence of dyeing temperature, dyeing pressure and dyeing time on the dyeing depth. Characterization methods including scanning electron microscopy(SEM), X ray diffraction(XRD), infrared spectroscopy(FT-IR) are used to analyse pretreatment and dyeing effect systematicly. The results are as follows:Kenaf fiber is pretreated by ionic liquid, by examining the pretreatment temperature and time, select the optimal parameters based on dye uptake rate, and circulation of ionic liquids were investigated, better cycle performance was resulted. The dyeing properties of pretreated kenaf fiber such as dye uptake, color fastness were improved compared with that of traditional dyed.After treatment with ionic liquid, interaction between the fibers weakened with the reduction of lignin, making the decrease of fiber crystallinity and the increase of surface roughness; Better integration of dye and fiber is the main reason for improving the dyeing effect; In this experiment, we use dyeing temperature, pressure, time, stroke as the main influence factors, obtained the optimum process parameters for supercritical carbon dioxide dyeing through orthogonal experiment: temperature 130℃, pressure 25 MPa, time 45 min, stroke 6mm.Using supercritical carbon dioxide on kenaf fiber dyeing, dyeing depth and washing fastness both reached the national standard, it is in line with the current policy requirements of low-carbon and energy-efficiency with short dyeing time, good levelness, harmless to the environment compared with the traditional dyeing; This study has great potential and prospects, providing strong data support for further research and application of supercritical carbon dioxide waterless dyeing technology, but there are still many problems to be solved that need further study.