Rigid polyurethane foams derived from soymeal polyols

摘要

Over the past decade, there has been an increased interest within the polyurethane industry to use natural oil based polyols, either as a stand alone product or in conjunction with petroleum-based polyols. The two main reasons for this growing interest are: heightened awareness of "green" issues that can minimize greenhouse gas emissions as well as reducing the dependency on non-renewable sources. Most of the polyols made from renewable resources that are suitable for polymerization into polyurethane resins have been prepared from vegetable oils. Only limited effort has been directed toward using protein biomass to produce value added industrial products due to difficulties associated with processing the meal and the high sensitivity of the proteins to moisture. Our group has recently developed new polyols from soymeal suitable for polymerization into rigid PU foams via an innovative cost-effective chemical route. In this process, soymeal is hydrolyzed to a mixture of amino acids, which are then directly propoxylated and converted to reactive polyols. This amino acid polyol mixture is characterized by low viscosity and high hydroxyl functionality. The preparation process and the characterization (FTIR, acid, amine and hydroxyl values) of this new soymeal-based polyols will be discussed and together with key properties of representative rigid PU foams (e.g. density, compressive strength, compressive strain at yield, flammability). These soymeal polyols were found to be self-catalytic and compatible with many conventional polyols allowing the formulator to adjust the properties of the foams as needed. Polyurethane foams prepared with 25% and 50% soy meal polyols exhibited comparable or better properties with these polyols that are most suitable for rigid spray foam formulations that require fast cure and high crosslink density.