Dyeing mechanism and multifunctional finishing of high performance aramid Yarns

Aramid fiber, also known as aromatic polyamide fiber, is a new type of high-tech synthetic fiber that plays an important role in aerospace, information technology, automobiles, oil and gas, civil engineering, and protection. Aramid fiber, like ordinary nylon fiber, belongs to the amide fiber class and contains amide bonds in the main chain of the molecule. The difference is that the amide bonds of aramid fiber are connected to the benzene ring, while the amide bonds of nylon fiber are connected to the fatty group. Aramid fiber is of great concern because of its lighter weight, higher strength, better durability, and high temperature resistance and acid and alkali resistance. As a reinforcement for the preparation of high-performance composite materials, it occupies an important position in high-performance fibers. Aramid fibers mainly include fully aromatic polyamide fibers and heterocyclic aromatic polyamide fibers. According to the different connection positions of the amide bond and the C atom on the benzene ring, they can be divided into ortho-aramid, para-aramid (PPTA) and meta-aramid (PMTA). The two main types of meta-aramid and para-aramid fibers that have been industrialized are as follows:

Experiment

1.1 Materials and Instruments Fabric: Nomex fiber (weight per unit area: 200 g/m Dupont). Reagents: Sodium carbonate, acetic acid, sodium nitrate (analytical grade, Sinopharm Chemical Reagent Co., Ltd.). Astrazon Orange RN 200% dye (DyStar Group), scouring agent DIADAVIN® UN, acid release agent TANACID® NA, cationic dyeable aramid dyeing agent Levegal C45, Levegal® C90, dispersing and leveling agent AVOLAN® IW liquid anti-pilling finishing agent Baypret Nano PU, C8 waterproof finishing agent Baygard UFC03, C6 waterproof finishing agent Baygard Clean, fluorine-free waterproofing agent Baygard 0427 (TANATEX Chemicals). Instruments: ME4002S/Z electronic balance, laboratory pH meter (Mettler-Toledo Group), Sandolab dyeing machine (Hongyi Technology Co., Ltd.), P-B0 horizontal roller dyeing resin machine, ModleR-3 automatic shaping and drying machine (Xiamen Ruibi Precision Machinery Co., Ltd.), Y571B friction fastness tester (Changzhou No. 1 Textile Equipment Co., Ltd.), BGY9802E light source box (BURKE Company), AATCC standard washing machine & dryer [Whirlpool (China) Co., Ltd.], spray tester, YG(B)406 fabric surface resistivity tester (Wenzhou Dayong Textile Instrument Co., Ltd.), Coloreye7000A colorimeter (X-Rite Company).

1.2 Experimental methods 1.2.1 Pretreatment formula: DIADAVIN® UN 1g/L, Na2CO3 2~3g/L. Process: Immerse fabric (bath ratio 10:1, 60~80℃, 30min) - wash twice → adjust pH. 1.2.2 Dyeing formula: Astrazon Orange RN 200% dye 1%~2% (omf) dyeing agent 25~50g, sodium nitrate 20g. Process: Set the dye bath temperature to 60℃, add dyeing agent, adjust pH to 3 with formic acid, add 2% AVOLAN® IW liquid and run for 15 minutes; add 1%~2% (omf) Astrazon Orange RN 200% (pre-dissolved), run at 60℃ for 5 minutes, heat to 80℃ at 2℃/min; add 20g sodium nitrate in 3~4 times (add within 45 minutes), check whether the pH is 3.0, heat to 130℃ at 1.5℃/min, run for 60~90 minutes, cool to 70~80℃, drain, and repeat washing at 80~85℃ (effectively remove residual dyeing agent and dye on the fabric surface)

1.2.3 Post-treatment Set the dye bath temperature to 60℃, add 0.5~1.0g/LAVO-LAN®IW liquid, 0.5g60% acetic acid, and run at 90℃ for 20min. If the fabric's color fastness to friction is not good, repeat the above operation; the fabric must be shaped and dried at 190~200℃ to remove residual dyeing agent. 1.2.4 Anti-pilling finishing formula: BaypretNanoPU20~40g/L.

1.2 Process: Adjust the solution pH to 5~6, padding (padding rate 70%~90%) →>140℃ baking. 1.2.5 Waterproof and oil-proof finishing formula: Waterproof and oil-proof finishing agent 20~60L. Process: Adjust the solution pH to 4~5, padding (padding rate 70%~90%) →120℃ drying →170℃ baking for 90s. 1.2.6 Anti-mosquito finishing formula: anti-mosquito finishing agent Eulan SPA 01 50~100 gL, enhancer EDOLAN AB 15~30 gL. Process: adjust the solution pH to 4, padding (pad rate 70%~80%) →> 100~120℃ drying → 140~170℃ baking for 60 s.

1.3 Test 1.3.1 Dyeing inflection point Prepare 9 10g fabric samples and 9 5g fabric samples for dyeing. Take out 10g fabric samples at 70, 80, 90, 100, 110, 120, 130℃, 130℃x45min, 130℃x90min respectively, and immediately measure 50mL of residual liquid into the dye cup, put in 5g fabric samples and continue dyeing. Observe the state of the fabric and test the K/S value. 1.3.2 Pilling resistance Refer to IS012945-2:2000 "Determination of pilling performance of textile fabric surface Part 2 Martindale method" for testing.

1.3.3 Waterproof and oil-proof Refer to AATCC22 "Water repellency test: spray method" and AATCC118-2002 "Oil repellency: hydrocarbon impedance test" for testing.

Results and Discussion

2.1 Anti-pilling When the dosage of BaypretNanoPU is 40g, the anti-pilling is level 3~4 at 2000 revolutions, and can reach level 3 at 4000 revolutions

2.2 Anti-mosquito performance Using EulanSPA01 containing permethrin as a mosquito repellent and acrylate EDOLANAB as a reinforcing agent can improve durability. The test results are in line with the theoretical calculation value range and have good water washing durability. 2.3 Dyeing inflection point As shown in Figures 1 and 2, the dyeing inflection points of Levegal®C45 and Levegal®c90 are both 100℃. At low temperatures, the dye is only adsorbed on aramid. When the temperature reaches 100℃, adsorption and desorption reach equilibrium, and the dye begins to react with aramid. When the temperature reaches 130℃, the reaction reaches equilibrium. Even if the reaction time is extended, the color depth only increases a little. Therefore, Levegal®C45 and Levegal®C90 can replace benzyl alcohol/acetophenone used for aramid dyeing with good results.

Conclusion

As a new material, aramid has high application value in industry. However, due to the particularity of its structure, there are some difficulties in dyeing and finishing. Adding dyeing agent Levegal C45 Levegal® C90 in the dyeing process can effectively improve the color yield. The functional finishing of conventional fabrics is also applicable to it. In the finishing process, appropriate adjustments can be made according to the basic properties of the fabric to obtain better functional finishing effects, which greatly improves the added value of the product.