Abstract: Nylon, also known as aliphatic polyamide fiber, exhibits excellent performance, such as lightweight, elasticity, good thermal stability, and mechanical property. Nylon has been widely used in the manufacturing of sportswear, stockings, conveyor belts, tents, industrial fabrics, and others. Nylon can be dyed by using acid dyes, reactive dyes, or disperse dyes. Nylon fabrics dyed with acid dyes offer vibrant color shades. However, its wet fastness is relatively poor. By employing reactive dyes, the dye molecules can form covalent bonds with nylon fibers by reacting with the amino end groups. Therefore, good color fastness to wet treatment can be achieved. However, reactive dyes usually display limited deep dyeing on nylon. And, the deeper the color, the more noticeable the reduction in color fastness. Dyeing of nylon using disperse dyes provides good levelness and penetration, however, exhibits poor color fastness property due to the low affinity between dyes and fibers. Reactive disperse dyes, which are constructed by attaching reactive groups to hydrophobic chromophores, combine the advantages of disperse dyes and reactive dyes. Currently, the most common approach to design reactive disperse dyes involves combining triazine and azo structures. This design concept is simple, effective, and allows for easy synthesis. However, reported molecular designs often directly combine the triazine structure with the primary amino group on the azo structure, greatly impacting the electronic effect of the azo chromophore and consequently affecting the color of the dye.
This paper aims to design seven reactive disperse dyes, E1―E7, by introducing dichlorotriazine moiety onto the hydroxyethyl group of the azo chromophore, and synthesize the designed dyes by using a two-step method including condensation reaction and coupling reaction. The structures of these dyes were characterized and confirmed by nuclear magnetic resonance spectroscopy, Fourier infrared spectroscopy, and high-resolution mass spectrometry. Nylon fabrics were dyed with reactive disperse dyes using a printing process. The composition for the printing paste was as follows: dye E1―E7 x%, Na2SO4 3%, NaHCO3 2%, urea 8%, sodium alginate 2.2%, and water. The printing process was performed under the condition of drying at 60 ℃ and steaming at 102 ℃.
We tested the properties of the dyed nylon fabrics, such as levelness, color depth, fixation value, color fastness, migration value, and breaking strength. The colors of nylon fabrics dyed with dye E1―E7 showed various colors of yellow, red, purple, and blue, respectively, with a color difference ∆E ranging from 0.16 to 0.28, which indicated good level dyeing performance. Nylon fabrics dyed with E1―E7 exhibited excellent resistance to organic solvent extraction. In comparison, the color of conventional disperse dye Disperse Blue SE-3RT on dyed nylon fabric can be completely stripped off by DMF. As calculated, dye E1 has the highest fixation value, reaching over 90%, while dye E5 has the lowest color fixation value of 74%. The other five dyes exhibit fixation values of above 80%. Due to the covalent bonding between reactive disperse dyes and fiber, the dyed nylon fabric demonstrates a good color fixing property. The nylon fabrics dyed with dyes E1―E7 exhibited color fastnesses to washing, rubbing, and sublimation of grade 4 or above. The dye migration values of dyed nylon fabrics were less than 5%. The breaking strengths of the nylon fabrics dyed with dyes E1―E7 ranges from 416 to 446 N, with a decrease in strength of only 1% to 7.6%, as compared with the original nylon fabric. This indicates that the dyeing of nylon fabric using dyes E1―E7 will not significantly damage the mechanical property.
The above results provide a new approach for the molecular design of azo-type reactive disperse dyes and their application in dyeing of nylon fabrics.

Key words: reactive disperse dyes, nylon, dyeing, fixation value, color fastness

摘要： 为提升分散染料染色锦纶的色牢度，在偶氮染料分子中引入二氯均三嗪结构作为活性基团，并采用三聚氯氰与N-乙基-N-羟乙基苯胺的缩合以及进一步与芳胺重氮盐的偶合等两步反应，设计合成出7支偶氮型活性分散染料。采用印花方式将所得活性分散染料对锦纶织物进行染色，测试染色锦纶织物的色深、固色率、色牢度、热迁移和断裂强力等性能。结果表明：染色锦纶织物具有良好的得色率、鲜艳性和匀染效果，同时具有良好的耐有机溶剂萃取性能。染色锦纶的固色率达到74%~90%，耐皂洗、耐摩擦和耐升华色牢度可达4级及以上，颜色迁移率不超过5%，显现出优异的颜色坚牢程度。该研究结果为具有高色牢度特性的锦纶染色用活性分散染料的研发提供了参考。

关键词: 活性分散染料, 锦纶, 染色, 固色率, 色牢度