Preparation of modified CO₂‐based polyurethane for wet‐type artificial leather with excellent alkali resistance

Abstract

Poly (propylene carbonate) diol (PPCD) is one of the most attractive CO2 copolymers. PPCD‐based polyurethane has excellent mechanical properties and hydrophilicity, and is widely used in various fields. However, poor alkali resistance limits the application of PPCD‐based polyurethane in wet‐type artificial leather (WPL). In order to solve this problem, polyurethane solution (PUS) for wet‐type artificial leather was prepared by using PPCD and polytetramethylene ether glycol (PTMG) as soft segments. The chemical structure, viscosity, molecular weight and distribution, physical and mechanical properties, thermal properties and dynamic mechanical thermal properties of PUS were characterized. The changes of the physical and mechanical properties of PUS films and surface morphology of WPLs after soaking in 10 wt% NaOH solution at room temperature for 24 h were studied, so as to evaluate the alkali resistance of polyurethane. The retention of tensile strength and tearing strength of PUS films modified by PTMG increased from 80% to 96% and from 89% to 100%, respectively. The scanning electron microscopy results showed that appropriate PTMG was beneficial to the formation of microporous structure for CO2‐based polyurethane leather. The leather without PTMG showed agglomeration phenomenon, the micropores were not obvious, and the changes were obvious after soaking in alkali solution. After being modified by PTMG, the morphology of leather after soaking in alkali solution was basically unchanged. Polyurethane leather prepared with PTMG and PPCD as soft segments has excellent alkali resistance. These results suggest that PPCD could be a potential artificial leather material.