| Silk is a natural protein fiber which has many excellent properties, it is known asthe queen of fiber since ancient times. But silk also has a fiaw, it is a kind ofnatural fiber which has the worst light stability. Especially with the increase ofultraviolet radiation, silk is more prone to photo-yellowing and photo-tendering etc.Research shows that the higher content tyrosine residues of silk protein have animportant influence on the light aging process.We choose six kinds of aromatic amine compounds containing different electron-donating group and electron-withdrawing group as the models of light stabilizercontaining aromatic primary amine. We selecte P-methylphenol as a model of the silkprotein tyrosine residues which can react with aromatic amine compoundsthrough Mannich reaction. The products and their corresponding intermediatecompounds were characterized by FT-IR,1H-NMR and Mass Spectrum, and theresults show that they were the target products as designed. The experiment resultsshow when the electron-donating group in the para amino, we can get a higherMannich reaction rate; when the electron-withdrawing group in the para amino, theMannich reaction rate is low, even unable to produce the target product. We useaniline respectively react with tyrosine and silk by Mannich reaction, and analysisthe Mannich reaction products of aniline with tyrosine and the hydrolyzing of silk byaniline Mannich method modified for Mass Spectrum, confirmed the feasibility ofaniline and silk protein tyrosine residues occur in Mannich reaction. Compared withthe silk intact, after UV irradiation for the same time, the photo-yellowing andstrength loss of silk by aniline Mannich modification is more serious.The designed and synthesized two kinds of aromatic amine compoundscontaining different fragments of light stabilizer, the one is containing primaryamine benzophenone UV absorber DP-1, the other is containing primary aminehindered amine light stabilizer HA-1. The products and their correspondingintermediate compounds were characterized by FT-IR,1H-NMR, Mass Spectrum andUV absorption spectrum, and the results show that they were the target products asdesigned. We used the two kinds of light stabilizers containing primary aminerespectively react with tyrosine and silk by Mannich reaction, and analysis the Mannich reaction products of light stabilizer with tyrosine and the hydrolyzing ofsilk by light stabilizer Mannich method modified for Mass Spectrum, proved thefeasibility of light stabilizer containing primary amine and silk protein tyrosineresidues occur in Mannich reaction.We also studied light stability of modified silk fabric by light stabilizer inMannich reaction. The experiment results show that, compared with the silk intact,after UV irradiation for the same time, the modified silk fabric in whiteness reducedthe smaller, and the breaking strength loss rate is lower, which showed light stabilityof the modified silk has improved. |
