Study On The Proccess And Mechanism Of Deeping Dyeing And Color Fastness Improvement Of Indigo Denim

Denim has good hygroscopicity and air permeability,and it has high strength and durability.Denim can also change its style with the changes of the times,making it comfortable and fashionable.It is suitable for people of different ages,races and sex.It has a broad market prospect.Denim is often dyed with indigo dye.Due to the low affinity between indigo dye and cotton fiber and the low dye uptake,it needs repeated impregnation and oxidation to achieve the ideal color;Indigo dyes have high initial dyeing rate,poor dye penetration,and most of the dyes are concentrated on the fiber surface,which makes the color fastness of indigo denim to wet rubbing only grade 1,which has become a difficult problem in the industry and seriously reduces the quality of denim;Denim dyed with vegetable Indigo is natural and environment-friendly,and has good antibacterial and health care effect.However,light denim with vegetable indigo dyed has low sun fastness and serious fading when wearing.Aiming at the technical problems of indigo dyeing,such as low dye uptake and complex dyeing process,this paper studies different types of cationic modifiers and their modification process and mechanism on cotton fabric,optimizes the indigo dyeing process,and studies the deepening process and mechanism of denim with deepening agent;In order to solve the industry problem of poor wet rubbing fastness of indigo denim,the pretreatment process was added,and the influence of dyeing process parameters on the wet rubbing fastness of indigo denim was studied;In order to improve the light color indigo denim fastness to sunlight,the optimization of fixing agent and fixing mechanism were studied,the results are as follows:Cotton fabric was modified by adsorption type cationic modifiers A,B,C,D and reactive type cationic modifiers E,F.The results showed that the K/S value of indigo dyeing of cotton fabric treated by adsorption type modifier and reactive type modifier was almost the same.The K/S value of indigo dyeing of cotton fabric treated by adsorption type cationic modifier B was increased from 10.90 to 20.13,After modification,the color fastness to soaping,dry rubbing,wet rubbing and sunlight of the dyed fabric reached 4-5,3 and 3-4 respectively.The dyeing depth of the modified cotton fabric can be the same as that of the unmodified cotton fabric when it is dipped and rolled twice.The optimized process parameters were as follows: modifier B 6 g/L,temperature 60 ?,time 20 min.The infrared spectrum shows that the modified cotton fabric has quaternary ammonium group.The zeta potential shows that the surface zeta potential of the cotton fabric modified by modifier B changes from-22.1 mV to +8.70 mV,which indicates that the quaternary ammonium group in the modifier changes the surface charge of the fiber from negative charge to positive charge,which makes the indigo leucophore anion easier to dye the positively charged cotton fabric,thus greatly improving the dyeing K/S value;Through the optimization of indigo dyeing process,the state of indigo cryptochrome can be adjusted to sodium monophenol,the affinity between indigo cryptochrome and cotton fiber can be increased,and the K/S value of denim can be increased.The optimized dyeing process is as follows: Dye 1.2 g/L,sodium hydrosulfite 18 g/L,Na OH 6 g/L,TD 1g/L,penetrant 6 g/L;After finishing indigo denim with F-4752,the dyeing K/S value can be increased by 80%.The optimized process parameters are as follows:F-4752 60 g/L,baking temperature 170 ?,baking time 90 s.The mechanism of deepening is that the silicone group in F-4752 reduces the surface refractive index of the fiber,and increases the K/S value by reducing the light reflection.After pretreatment with scouring agent A,the dye permeability of cotton yarn increases and the wet rubbing fastness increases from grade 1 to grade 2.The scouring conditions were as follows: scouring agent A 10 g/L,Na OH 10 g/L,scouring temperature 95 ?,scouring time 30 min;Through the optimization of indigo dyeing process,the state of indigo cryptosome can be adjusted to sodium bisphenol salt,the dye permeability can be increased,and the wet rubbing fastness of denim can be increased from grade 1 to grade 2.The optimized dyeing process is: Indigo 1.2 g/L,Na OH 10 g/L,sodium hydrosulfite 18 g/L,TD 1 g/L,penetrant 6 g/L;After finishing with polyurethane fixing agent B,the wet rubbing fastness of indigo denim can be improved by 1.5 grades.The finishing process is as follows: fixing agent B 70 g/L,baking temperature 160 ?,baking time 120 s.The infrared spectrum shows that the fixing agent is a polyurethane compound,which forms a film on the surface of the fabric and improves the wet rubbing fastness by reducing the friction coefficient.The fixing agent with larger molecular weight has higher film-forming strength on the surface of the fabric and improves the wet rubbing fastness.In addition,the denim fabric with soft finish and fixation treatment can not only have good wet rubbing fastness,but also ensure soft and smooth handle.The cotton fabric was modified by adsorption cationic modifier B,and the dyeing process of indigo dye was optimized by using caustic soda glucose reduction system.The suitable dyeing process was as follows: dye concentration 0.8 g/L,sodium hydroxide 10 g/L,glucose 30 g/L,penetrant 6 g/L,dyeing temperature 20 ?,soaping fastness of dyed indigo denim was 4-5,The dry rubbing fastness is 4-5,the wet rubbing fastness is 3,and the color fastness to sunlight can reach 3.The soaping color fastness of light indigo denim is 5,the soaping staining fastness is 4-5,the dry rubbing fastness is 5,the wet rubbing fastness is 3-4,but the color fastness to sunlight is only 2;After finishing with fixing agent 708,the light fastness of denim dyed with indigo can be improved by 0.5 grade.Adhesive TF-239 H can improve the durability of colouring agent 708 on denim.The suitable finishing process is as follows: fixing agent 708 60 g/L,adhesive TF-239 H 70 g/L,curing at 160 ? for 3 min.UV spectrum showed that the fixing agent 708 had absorption peaks at 308 nm(UVB)and 352 nm(UVA),which indicated that the fixing agent 708 could absorb ultraviolet light in different wavelength range,prevented the breaking of C=C bond of indigo dye under UV irradiation,and improved the light fastness of indigo dyed denim;The results showed that the indigo dye with absorption peaks at 563 nm and 610 nm in methanol solution was vegetable indigo dye,Indigo dyed denim has absorption peaks at 563 nm and 610 nm at the same time.