氧化柿单宁的制备、结构及其上染真丝的染色工艺OA

The traditional persimmon dyeing process is highly praised for its natural source and unique aesthetic value,but there are limitations such as long oxidation period and unstable dyeing efficiency.To optimize the process,the enzymatic oxidation method was improved in this study,and the catalytic effects of four different oxidases(Ox-1 to Ox-4)on persimmon tannin dyed silk fabrics were systematically compared.By comprehensively evaluating the dyeing depth,hue and uniformity,Ox-4 was finally determined to be the best oxidase.In this study,two kinds of oxidized persimmon tannin were prepared.Ox-4-oxidized persimmon tannin treated by Ox-4 enzyme and air-oxidized persimmon tannin were used to compare the chemical characteristics and practical application differences between enzyme-controlled oxidation and natural atmospheric oxidation. Fourier transform infrared spectroscopy(FTIR)and liquid chromatography-mass spectrometry(LC-MS)were used to characterize the two oxidized tannins.Analysis showed that both of them contained gallic acid,(+)-catechin,quercetin-3-O-glucoside,ethyl ferulate and other key phenolic substances,but epicatechin gallate dimers were detected in air-oxidized samples.This component may be derived from non-specific oxidative coupling under environmental conditions,but this substance was not detected in Ox-4 oxidized samples.On the basis of chemical characterization,the dyeing properties were studied by key parameters such as dye mass fraction,pH value(3～9),temperature(50～90℃)and time(30～180 min),and the color coordinates(L*,a* and b*),K/S value and reflectivity were measured. The optimum process parameters of Ox-4 oxidized persimmon tannin dyed silk fabric were determined by experiment as follows:a temperature of 90℃,a pH value of 6～7(weak acid to neutral),and a dyeing time of 120-150 min.Under optimal dyeing conditions,the fabric exhibited excellent colorfastness,achieving grade 3 or above in standard tests for wash fastness and rubbing fastness(dry/wet).Research indicates that the Ox-4 oxidase can effectively regulate and accelerate the oxidation process of persimmon tannin.By replacing the uncontrollable slow air oxidation step with an enzyme-controlled reaction,it achieves subjective regulation and standardization of the traditional dyeing process.The established optimal parameters not only enhance dyeing efficiency and reproducibility but also ensure that the finished product possesses colorfastness with commercial application value,providing data reference for the modernization and wider application of this traditional natural dyeing technique.