Synthesis and properties of low-viscosity compound aliphatic waterborne polyurethane foamed resins with high solids content for textile artificial leather

In the field of textile foamed artificial leather, the development of environmental protection high-foaming waterborne polyurethane foamed resins has always been an important research direction. However, achieving foamed resins with high solids content and low viscosity in order to reduce cost and increase efficiency has been a challenge. A compound aliphatic waterborne polyurethane (AWPU) with high solids content and low viscosity was prepared by pre-polymerization method. The results showed that R value (-NCO/OH molar ratio), D value (hydrophilic group content), A-95 M ratio and IPDI/HDI molar ratio were critical in achieving the characteristics of high solids content and low viscosity of the resins through the synergistic effects of size, particle size distribution , and “electric double-layer”, respectively, and the corresponding resins also had a satisfactory foaming ratio. When R = 2.0, D = 2.8 wt%, A-95 = 0.5 wt%, IPDI/HDI = 5:5, the prepared AWPU resins had good appearance and stability, the solids content could reach 53.5 %, the viscosity is only 175 mPa·s. And the foaming ratio of AWPU-H foamed resins could reach 3.04 (CaCO 3 powder as a filler could reach 2.67), and the foamed layers holes formed are continuous, uniform, and non-collapsing. In terms of application performance, the air permeability and water vapor permeability of the prepared AWPU-H foamed leather could reach 187.32 mm/s and 277.88 g/m 2 ·h, respectively. These results clearly show the great potential of AWPU-H foamed resins in the field of foamed artificial leather. • The AWPU-H foamed resin with solid content up to 53.5 % and ultra-low viscosity (175 mPa·s), giving good fluidity and processing adaptability. • The foaming ratio of the resin is up to 3.04 and has a fast foaming speed in just 5 min, which greatly improves the production efficiency. • The foamed artificial leather has excellent air permeability and moisture permeability, which can meet the needs of high-end market.