The effect of ester and ether ratio on air permeability, windproof and mechanical properties of solvent-free water-based polyurethane foam

Solvent-borne polyurethane (PU) is the main product in PU synthetic leather, which has soft handling, breathability, and moisture permeability properties by wet type. The PU film would produce the irregular foam cell by solvent exchanging water. This traditional process would use a lot of dimethylformamide, and it causes much pollution of the environment. Therefore, the water-borne polyurethane system is essential in the textile industry. This study adopted the patented prepolymer process for solvent-free water-borne polyurethane (SFWPU); the foam was formed by a blowing agent and then, coated on the polyester textile with SFWPU foam by coating machine. This research focuses on the polyol composition equivalent ratio of poly(1,4-butylene adipate) glycol (PBA) and poly(tetramethylene ether) glycol from 30:70, 20:80, 10:90, and 0:100. The crystallinity increased on the foam properties with increasing the PBA composition, affecting the foam and tensile properties. Moreover, this research finds that higher crystallinity polyol of PBA contents increased, modulus of SFWPU is increased, and tensile strength is decreased. The scanning electron microscope finds the foam cell would expand by increasing PBA contents, which affects the textile’s air permeability and water vapor transmission. The 10% PBA equivalent of ester–ether type SFWPU foam coated on textile, which has windproof and keeps the moisture permeability.