Clothing Knowledge: Some Tips To Prevent Silk Pajamas From Yellowing

Scouring bleached real silk And real silk, in storage or taking, will produce yellowing and discoloration, which will reduce the value of goods. The yellowing of real silk is mainly due to the oxidation and coloring of amino acid residues such as tryptophan and tyrosine in silk protein in the air. The existence of light can promote this phenomenon.

There are several methods to prevent yellowing of real silk:

① The Foreign Dyes Digest reported that the bleached silk was soaked in 0.5% NaOH aqueous solution for 3s, and after being squeezed (with a rolling surplus of 80%), it was put into an aqueous solution composed of 1% thiourea and 1% 1,3,5-triacryl hexahydrotriazine, soaked at 70 ℃ for 30min, and then washed. Then treat with 0.3% HCl at 70 ℃ for 30min, wash and dry. The yellowing index of silk treated with the above method is 2.8. 3.8 after 180 days.

② Treated with chitosan. Add 0.3-1.5g of deacetylated chitosan into 300mL of 1% acetic acid aqueous solution to prepare 0.1% ～ 0.5% deacetylated chitosan solution × 10 cm) in this solution, fully dry at 80 ℃, and form chitosan film on the surface of silk fiber. Illuminate the treated silk with carbon arc light (20, 40 h), and measure its yellowing degree with automatic Hunt white photometer. As a result, compared with untreated silk, the yellowing degree of silk treated with chitosan was lower.

③ Treat with anti yellowing agent HN-200. Anti yellowing agent HN-200 is Japan An antioxidant produced by a company. Its function is to provide electrons to active free radicals or act as hydrogen atom donor, so as to terminate the chain type autocatalytic photooxidation reaction, thus providing an effective anti yellowing effect on real silk. The method is to treat the silk with 0.2% HN-200 at 80 ℃ for 5~10min and then dry it. The yellowing index increment (△ Y1) of treated silk after 100 h xenon lamp irradiation is only about half of that of untreated silk. However, this kind of anti yellowing agent has high water solubility and low affinity with fiber, so its washing resistance is not ideal.

④ The compound processing technology of dimethylol vinyl urea resin and polyurethane was used. Silk can be treated with DMEU resin and polyurethane 105 resin to prevent yellowing. The method is as follows: dip the whitened 07 silk crepe de chine in a working solution composed of DMEU 100 g/L, polyurethane 105 40 g/L, magnesium chloride 20% (for resin weight) and citric acid 5% (for resin weight) at room temperature for 15 min, then pre bake it at 80 ℃ for 4 min, bake it at 140 ℃ for 3 min, and then soap it at 50 ℃ for 10 min (1 g/L soda ash and soap flakes respectively), and wash it with water at 50 ℃, Wash thoroughly and dry. The anti yellowing effect is: 200h illumination △ Yl is 8.69, and the untreated sample is 15.06. If 0.5% UV-284 (anti ultraviolet finishing agent) and 1% HN-200 are added to the composite resin working fluid effect Better.