Stability of Aqueous Tea Extraction for Textile Dyeing

摘要

The aqueous green tea extraction could be served as natural dye for textile dyeing. The active substances of tea extraction such as polyphenolic compounds, catechins impart the dyed textiles antioxidation and anti-UV. The dyed textiles, therefore, are considered as healthcare products. The extraction processings including temperature, extraction times, and ratio of tea and distilled water were studied. The absorbance of dye bath was used to evaluate the optimum extraction processing. The resulting extraction at 100℃ and ratio of tea and distilled water 1∶50 was used in the following experiments. The stability of tea extraction on pH, temperature, storage was investigated in terms of absorption curve at band from 200 ～800 nm. The dyeing was carried out with cotton fibers as carriers and analyzed with orthogonal experiment. Dye concentration, pH of dye baths, and dyeing temperature were selected as the examined factors influencing dyeing properties. No mordant agents were added to the dyeing process. The colour of fibers was tested on Spectra-flash Plus matching system in terms of K/S and colour difference (△E). The results show that cotton fibers show reddish yellow colour after dyeing with green tea extraction. The pH of dye bath is the most sensitive in affecting colour of cotton fibers among the three examined factors, which is consistent with the study on the stability of tea extraction. The deep shade (K/S = 1.530, △E = 16.670) is obtained at conditions of pH 8, dye concentration × (undiluted dye bath), and dyeing temperature 100℃ for 1 h. The presented results prove the feasibility of using aqueous tea extraction as dyes for cotton fibers. The fastness and colorful shades, however, would be the important aspects for textiles dyeing, which deserve to be further studied in the future work.