Abstract:

Objective As a high-end fabric coating agent, water-based polyurethane holds vast development potential. In-depth research along this line will not only help improve the quality and performance of domestic coating products but also promote technological progress and innovative development in the textile coating industry. Compared to traditional solvent-based polyurethanes, water-based polyurethanes are more environmentally friendly, with lower VOC emissions, aligning with current green and sustainable trends. Additionally, the water-based polyurethanes can add more functionalities and value to textiles, enhancing the market competitiveness of products.

Method Using polyethylene glycol monomethyl ether (MPEG) and itaconic acid (IA) as the raw materials, itaconic acid polyethylene glycol monomethyl ether ester (IM) containing C=C double bonds was synthesized via esterification reaction, and IM was characterized using infrared spectroscopy and nuclear magnetic resonance spectroscopy. After mixing IM with hydroxyethyl methacrylate-terminated water-based polyurethane (HWPU), a water-based polyurethane fabric coating agent terminated with itaconic acid polyethylene glycol monomethyl ether ester (WPU-IM) through UV grafting was obtained. The properties of the WPU-IM film and fabric coating were analyzed using infrared spectroscopy, water absorption tests, tensile tests, hydrostatic pressure resistance tests, and water vapor transmission rate tests.

Results With the increase in the mass fraction of WPU-IM, the water absorption rate of the film rose from 6.8% to 17.9%, and the water contact angle was decreased from 90.4° to 78.1°, indicating an enhanced hydrophilicity of the film. Meanwhile, the water vapor permeability of the coated fabric rose on the increase in WPU-IM content, demonstrating that the introduction of polyethylene glycol segments can improve the moisture permeability of the waterborne polyurethane fabric coating agent. When the mass fraction of IM is 2.1%, the water vapor permeability of the fabric coating reached 4 086.3 g/(m²·d), consistent with the moisture permeability mechanism of hydrophilic non-porous membranes. When increasing the mass fraction of WPU-IM, the elongation at break of the film was gradually increased, reaching 325% when the mass fraction of IM is 2.1%, which indicated improved ductility of the film. However, the tensile strength of the film and the hydrostatic pressure resistance of the coated fabric demonstrated a decrease with the increase in the mass fraction of WPU-IM, with the tensile strength dropping from 12.63 MPa to 5.49 MPa and the hydrostatic pressure resistance decreasing from 27.12 kPa to 17.31 kPa.

Conclusion The synthesized WPU-IM, using IM as a biomass raw material and by introducing polyethylene glycol hydrophilic chain segments into the polyurethane chain through free radical polymerization, can effectively improve the moisture permeability of water-based polyurethane fabric coating agents and enhance the ductility of the coating film. However, it is also found that excessive introduction of WPU-IM is not conducive to the water resistance and mechanical strength of the fabric coating.

Key words: coating agent, hydrophilic monomer, methoxypolyethylene glycol, itaconic acid, waterborne polyurethane, ultraviolet grafting, fabric coating