Migration and Chemical Characterization of Cyclic Oligomers from Polyester Fiber in Waterless Dyeing System

Liujun Pei,Liujun Pei,Hongjuan Zhang,Zhiwen Wang,Jiping Wang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.9

Polyester yarn is successfully dyed with disperse dye in a low-pressure non-aqueous medium dyeing system. However, oligomers with different low molecular mass are formed during manufacture of polyesters, which can diffuse intothe dyeing bath or be adsorbed on the dyeing machine during dyeing process. In this investigation, oligomers of differentpolyester yarns were extracted with tetrachloroethane solution, and analyzed using Fourier transform infrared spectroscopy(FTIR), proton nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), high performance liquidchromatography (HPLC), and liquid chromatography-mass spectrometry (LCMS). The amount of oligomer that was isolatedby reprecipitation method ranged from 1.83% to 4.07 % (on the weight of yarn) in the respective yarn, and more than 80 %of the components are cyclic oligomers. The thermal profile of oligomer showed it had a faster weight loss at 183 °C and470 °C which was compared with polyester (473 °C). HPLC and LC-MS analysis results further indicated that 99 % of theoligomers were cyclic trimers during dyeing. Moreover, the dyeing color depth of dyed yarn and the uptake of dye would begreatly improved after the oligomer of polyester yarn was removed. Otherwise, the oligomer may affect the color fastness andlevelness of the dyed polyester samples.

Salt-Free and Alkali-Free Fixing Method of Wool Fabric Dyeing in Non-Aqueous Media Dyeing System

Liujun Pei,Jingyuan Yi,Jingru Chen,Wenhua Shi,Wenzhao Cao,Hongjuan Zhang,Jiping Wang 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1

Non-aqueous media dyeing is an important water-saving and salt-free dyeing technology in the textile dyeing industry. In thisinvestigation, a salt-free and alkaline-free dyeing technology was developed for wool fabrics. After padding with reactivedye solution, wool fabric was fixed in a non-aqueous medium at 90 °C for 90 s. After washing, the fixation of reactive dyecan achieve more than 98% in a salt-free and alkali-free dyeing environment. The effect of fixing method on the physicalproperties of wool fabrics was analyzed by TGA, DSC, and XRD. Compared with steam and cold batch fixing method, thefixing process in non-aqueous medium has little effect on the mechanical properties of wool fabrics. The final decompositiontemperature of wool fabric dyed with non-aqueous medium was about 46 °C, which was higher than that of the fabric samplesdyed by other methods. Moreover, the crystallinity of wool fiber was increased after non-aqueous fixation process. And nonaqueousmedium had no influence on the surface morphology of wool fabrics. For non-aqueous medium and steaming fixingmethods, there were only hydrolyzed dyes, but some hetero-bifunctional dyes were detected in the cold batching system,indicating that reactive dyes could effectively react with wool fibers in non-aqueous medium and steaming fixing system.

Continuous Pad Dyeing of Cotton Fabric in a Non-Aqueous Medium for Realizing Ultra-High Fixation and Washing-Free

Zhiwen Wang,Liujun Pei,Hongjuan Zhang,Hao Li,Jiping Wang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.5

In traditional water-based dyeing system, a low fixation of reactive dye requires six to ten times washing afterdyeing, which consumes a lot of water and results in huge dyeing effluent. To alleviate this issue, the development of asustainable dyeing technology of cotton textile is essential. In the present investigation, silicone non-aqueous medium wasemployed to improve the fixation of dye with a pad-dyeing process under the optimized dyeing parameters. The appropriatewashing-free dyeing conditions were recommended as follows: the padded fabric was placed at 105 oC for 15-30 s tocomplete pre-drying to decrease the water content rapidly, and then fixed in non-aqueous medium for 80-90 s at 95 oC. Afterdyeing, the dyed fabric was treated with 30 g/l fixing agent through pre-dried at 80 oC and baked at 160 oC. The resultsindicated that the final fixation of dye was above 95 %, and the dry rubbing fastness of dyed cotton fabric can reach grade 5. Moreover, the wet rubbing fastness and washing fastness of dyed cotton fabric can reach grade 3-4 and 4, respectively. Therefore, it can obtain the washing-free dyeing of cotton fabric with reactive dye. If the washing procedure was omitted inthe industrial application, the environmental cost of cotton dyeing would be greatly decreased. This method provides asubstantial reduction in wastewater effluent, which will be considerably potential for industrial application.

Synthesis and Application of Reactive Dyes Based on Azo-Anthraquinone Skeleton to Realize Clean Printing of Cotton Fabrics

Hongjuan Zhang,Liujun Pei,Shuaitong Liang,Qun Wang,Jingming Huang,Xiaomin Gu,Jiping Wang 한국섬유공학회 2021 Fibers and polymers Vol.22 No.5

Traditional reactive dyes generate a large amount of colored wastewater during printing owing to low reactivity,causing severe environmental problems. In this investigation, four novel reactive dyes were synthesized via incorporating azostructure into anthraquinone chromophore. They were characterized by UV-Vis, FT-IR, and 1H-NMR spectra. Their printingproperties on cotton fabric were comprehensively studied. Attributed to multifunctional groups, the fixation of the novelreactive dyes can reach 98 % even at the dye concentration of 10 %. It increases by 30 % compared with traditionalanthraquinone dyes. Moreover, the reactive dyes containing both mono-chlortriazine and bis(sulfatoethylsufone) groups canachieve urea-free printing. This research has a potential and significant application in the cleaner production of printing forcotton fabrics.

Single-step Single Bath Dyeing and Finishing of Nylon with Disperse Dye and Chitosan by Using Decamethylcyclopentasiloxane Solvent as Dyeing Media

Muhammad Asad Saleem,Liujun Pei,Jiping Wang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6

This investigation was conducted to reduce the water and raw material consumption, and shorten the processingtime by carrying out the dyeing and finishing process in a single-step and a single bath by using decamethylcyclopentasiloxane(D5) solvent as dyeing media. The nylon fabric was dyed with disperse dye and finished with chitosan in D5 solvent in asingle-step. To improve the durability of the chitosan finish, the chitosan was ball milled into nanoparticles. Furthermore,nylon fabric was dyed with a high dye concentration, 3.2 %(o.w.f.), for assessing the feasibility of a single-step dyeingprocess for darker shades. Antibacterial activity, color strength, and SEM analysis of treated fabrics reveal that nylon fabriccan be dyed and finished in a single step and single bath in D5 solvent. As compared to conventional aqueous dyeing, thesingle-step dyeing and finishing methodology yielded 53 % higher color strength. The 100 % reduction in bacteria colonyforming units (CFU) was achieved with a 1 % concentration of milled chitosan. The fabric treated with milled chitosansustained its antimicrobial activity even after 5 washes.

Substituent-Dyeing Properties Relationship of Disperse Dyes on Polyester in Low Pressure Waterless Dyeing System

Shunjie Yu,Hongjuan Zhang,Liujun Pei,Shuaitong Liang,Aixue Dong,Jiping Wang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.2

Decamethylcyclopentasiloxane (D5) has attracted an increasing attention because it can realize waterless dyeing ofchemical fibers. In this paper, two azo disperse dyes with different substituents were synthesized, and compared with C.I. Disperse Red 73 to study the relationship between structure and dyeing properties systematically in D5 media. The resultsshowed that the dyeing uptake of dyes increased from 85.5 % to 98.0 % with the substituent changing from N-ethyl to Nacetoxyethylgroup. This was because the solubility of dyes in D5 media showed an evident reduction. Although the dyescontaining N-cyanoethyl group had the lowest solubility, the dyeing uptake became 93.4 %, which was slight lower than thatof dyes with N-acetoxyethyl group. This was because an introduction of N-cyanoethyl group increased dye molecularaggregation in D5 media, making it difficult to diffuse. Additionally, the dyes with N-ethyl or N-acetoxyethyl groups showedbetter washing fastness and rubbing fastness than that of dye containing N-cyanoethyl group. These results provide apotential theoretical guidance for improving exhaustion of disperse dyes in waterless dyeing system. This study will promotetextile industry sustainable development.