Abstract:

Objective The molecular chain structure of meta-aramid fiber is relatively regular, coupled with strong hydrogen bonding between the molecular chains, and it has excellent mechanical properties and comprehensive properties. Its disadvantages lie in its difficulty in dyeing due to its regular molecular structure, high crystallinity, high orientation and high glass transition temperature, which limits its further application. This research was carried out in order to improve the combination of meta-aramid fibers and dyes, improve their dyeing properties, and further expand the application of meta-aramid fibers in the field of post-dyeing.
Method This research uses solution polymerization method to add the form of the third monomer in the polymerization process, introduce easy-dyeing groups into the molecular structure of polyphthaloyl-m-phenylenediamine, adjust the number of easy-dyeing groups, and then adjust the molecular structure of the polymer to achieve the objective of easy dyeing.
Results In this paper, 4,4'-diaminophenyl sulfone (DDS) was selected as the third monomer, and the modified meta-aramid fiber was prepared by adjusting the content of sulfone group in the molecular chain. The results show that the dyeing property of modified meta-aramid fiber was significantly improved with the increased amount of DDS. When the molar ratio of m-phenylenediamine to DDS was set to 7∶3, the modified meta-aramid fiber maintained good mechanical properties, and the prepared modified meta-aramid fiber showed excellent dyeing property (Tab. 1). After that, the dyeing properties of modified meta-aramid fiber, conventional meta-aramid fiber and imported XJ easily dyed meta-aramid fiber products were analyzed. The K/S value of the modified meta-aramid fiber prepared in this research using Cationic Red FBL dye was 3.82, 1.39 higher than that of conventional meta-aramid fiber. The K/S value of Cationic Blue FGGL dye was 5.83, which is 2.74 higher than that of conventional meta-aramid fiber. The K/S value of modified meta-aramid fiber dyed with Disperse Red S-GS dye was 4.61, 2.44 higher than that of conventional meta-aramid fiber, and the K/S value of Disperse Blue S-GL dye dyeing was 1.45, 0.94 higher than that of conventional meta-aramid fiber (Tab. 3). The dyeing effect of modified meta-aramid fiber was significantly improved by using different dyes for dyeing analysis.
In order to further verify the dyeing effect of modified meta-aramid fiber, the modified meta-aramid fiber was spun and woven into a fabric. The mechanical properties, flame retardancy and color fastness after dyeing of the fabric were tested. Compared with conventional meta-aramid fiber, the mechanical properties and flame retardancy of modified meta-aramid fiber did not change significantly. The color fastness to dry and wet grinding and light fastness were improved by 1 level. From this point of view, sulfone group was introduced into the molecular structure of meta-aramid fiber, the combination of the fiber with cationic dyes and disperse dyes has been significantly improved, and thus achieves the objective of easy dyeing. After the fabric is woven, the post-dyeing is carried out. Compared with the imported easy-dyeing meta-aramid fiber products, the dyeing property is equivalent to the imported XJ easy-dyeing meta-aramid fiber, and its mechanical properties, color fastness and other aspects are better.
Conclusion An easy-dyeing meta-aramid fiber product with excellent comprehensive performance was successfully prepared.The research results are expected to be applied in the field of individual protection in the future, to protect people's lives and property. The development objective of easy-to-dye interposition aramid fiber products is to improve the production technology level of high-performance fiber in our country, and speed up the process of substitution of domestic interposition aramid fiber in various fields.

Key words: solution polymerization, wet spinning, meta-aramid, easy to dye, dyeing property