The effects of ether, ester, carbonate polyol and hydrophilic group contents on the mechanical properties and abrasion resistance of solvent-free water-based polyurethane foam

Abstract

The traditional artificial leathers were produced by wet process. In this process, organic solvent DMF was needed to employ large amounts of water and DMF, which caused serious environmental pollution and consumed a lot of energy for the recycling solvent process. This study used sustainable solvent-free waterborne polyurethane (SFWPU), an eco-friendly foam coating to replace DMF wet-process PU leather products without using a large amount of DMF and solvent-treating equipment to keep from high energy consumption. This study addresses the optimization of solvent-free waterborne flexible polyurethane (FPU) foams obtained from polyols with different chemical structures and hydrophilic group contents based on the foam ratio and abrasion resistance. For this purpose, the study adopted a patented prepolymer process to synthesize SFWPU, which was subsequently expanded to foam by using a physical blowing agent. Diverse polyol with ether, ester, and carbonate types and hydrophilic contents synthesize a series of SFWPUs. These strategies are mainly focused on the foam ratio, mechanical properties, foam structure, and abrasion resistance of FPU foams. This study showed that polyol type did not significantly affect the foam ratio. However, scanning electron microscopy revealed that the foam cells on the ether and carbonate types of the FPU foams were increasingly smaller. For this reason, the carbonate diol and ether diol of FPU foams have better abrasion resistance than ester-type polyols of FPU foam. The hydrophilicity of the foam affects the foam ratio, mechanical properties, foam cell, and abrasion resistance. The 5 wt.% hydrophilic content of carbonate-type FPU foam has better abrasion resistance, which is only 0.25 w.t.% weight loss after the Taber abrasion test. An adequate combination of these components leads to better abrasion resistance and an appropriate foam ratio, which can replace DMF wet process PU leather.