Abstract:  Forming robust covalent bonds between dyes and fibers is an effective strategy to address the issue of thermal migration in disperse dyes. The emergence of diazirine-type dyes in recent years, which form reactive carbene intermediates upon high-temperature initiation and can undergo chemical reactions with the C-H bonds on polyester fibers, offers the potential to establish dye-fiber covalent bonds. The purpose of this article is to reveal the dyeing mechanism of these reactive dyes on polyester fabrics and provide insights for the development of high-performance diazirine dyes through studying the dyeing process of two synthesized diazirine dyes on polyester fabrics. Initially, two diazirine-type blue dyes, D1 and D2, were synthesized through coupling reactions between aniline derivatives containing diazirine structures and the corresponding diazonium salts. Subsequently, the dyes were applied to dyeing polyester fabrics using a high-temperature and high-pressure dyeing method. Various parameters, including dye uptake, color depth of the dyed fabrics, fixation rate, dye migration rate, and color fastness, were tested and analyzed to ascertain the reactivity of diazirine dyes towards polyester fibers and to further reveal the dyeing mechanism of these dyes onto the fibers.
The absorption spectrum test results showed that the maximum absorption wavelengths of dyes D1 and D2 in N,N-dimethylformamide were located at 584 nm and 601 nm, respectively, with corresponding molar extinction coefficients of 35,800 L/(mol·cm) and 35,200 L/(mol·cm). The thermogravimetric and DSC curves showed that dye D1 exhibited better thermal stability than dye D2, which would be beneficial for maintaining the stability of the diazirine dye molecules during the dyeing process. In dyeing polyester fabrics using high-temperature and high-pressure dyeing method under a dye concentration of 1% (o.w.f.), the dye uptake rates of D1 and D2 were 93.3% and 85.9%, respectively. The corresponding K/S values of the dyed fabrics were 17.1 and 15.0, with fixation rates of 59% and 36%, dye migration rates of 8.2% and 20.4%, and color fastness ratings to soaping, rubbing, sublimation, and thermal migration reaching 4 to 5 grades or above. Dyeing experiments conducted at different holding temperatures also confirmed that the reaction effect between dye D1 and the fiber improved more significantly than that of dye D2 as the temperature increased. The dyeing rate curves during temperature rise indicated that dye D1 adsorbed onto the fiber faster than dye D2. This would lead to a much higher reaction rate between dye D1 and the fiber during the holding stage compared to dye D2. 
From the above results, it can be concluded that diazirine dyes with better stability and faster adsorption and dyeing properties can achieve relatively better fixation performance on polyester fabrics.

Key words: reactive disperse dye, diazirine, polyester, thermal migration, dyeing mechanism

摘要： 为解决分散染料染色涤纶织物耐热迁移性差的问题，设计合成2只含有双吖丙啶结构的蓝色活性分散染料D1和D2，采用高温高压染色工艺对涤纶织物进行染色，测试了染料上染率、染色织物色深度、固色率和色牢度等染色性能，探讨了反应性基团对涤纶织物染色性能的影响。结果表明：当染料用量为1%(o.w.f.)时，染料D1和D2的上染率分别为93%和86%，染色织物K/S值分别为17.1和15.0，固色率分别为59%和36%，染料移染率分别为8.2%和20.4%。与对比染料相比，双吖丙啶染料染色涤纶织物的耐皂洗、耐摩擦、耐升华和耐热迁移等各项色牢度等级均得到了显著提升。研究结果可为开发耐热迁移性分散染料提供新思路。

关键词: 活性分散染料, 双吖丙啶, 涤纶, 热迁移, 染色机理