Fluorine-free waterborne polyurethanes modified with bis-amino silane coupling agent: synthesis and properties

Series of anionic waterborne polyurethanes (WPU) were synthesized with isophorone diisocyanate (IPDI) and polycaprolactone diol (PCL). Silane coupling agent (KH-792) was introduced into waterborne polyurethane system as modifiers. The effect of KH-792 contents on the properties of waterborne polyurethane was investigated. The Si-O bonds in KH-792 would be hydrolyzed into Si-O-Si bonds in the WPU system, forming a cross-linked network and improving the hydrophobic properties of WPU. The experimental results showed that the introduction of KH-792 significantly improved the glass transition temperature, thermal stability and water resistance of films. When the content of KH-792 was 1.5%, the comprehensive property of film was the best: the tensile strength was 26.80 MPa, the elongation at break was 693.83%, the adhesion was 1.74 MPa, and the T-type peel strength was 13.95 MPa. This offered a research basis for developing a new type of waterborne polyurethane fabric coating with strong adhesion, high mechanical properties and good water resistance.