Isocyanate Reduction by Epoxide Substitution of Alcohols for Polyurethane Bioelastomer Synthesis

Abstract

A phosphate ester-forming reaction was carried out by mixing epoxidized soybean oil with up to 1.5%o-phosphoric acid.In situoligomerization took effect almost instantly producing a clear, homogeneous, highly viscous, and a low-acid product with a high average functionality. The resulting epoxide was used as a reactant for urethane bioelastomer synthesis and evaluated for rigid foam formulation. Results have shown that with a number of catalysts tested phosphoric acid significantly enhances a solvent-free oxirane ring cleavage and polymerization of the epoxidized soybean oil via phosphate-ester formation at room temperature. The resulting phosphoric acid-catalyzed epoxide-based bioelastomer showed an 80% decrease in extractable content and increased tensile strength at the same isocyanate loading relative to the noncatalyzed epoxide. The oligomerized epoxidized soybean oil materials exhibited ASTM hydroxyl values 40% less than the nonoligomerized starting material which translates to reduced isocyanate loadings in urethane applications.

Physical Properties of Soy-Phosphate Polyol-Based Rigid Polyurethane Foams

“…Soy-phosphate polyol (SPP) was prepared at the University of Missouri and its specification is shown in Table 3. It was made by an acidolysis reaction as shown in Figure 1 [18]. Full-epoxidized soybean oil (7.0% oxirane, Vikoflex 7170, Arkema, King of Prussia, PA) was reacted with 1.5% o-H 3 PO 4 (85% aqueous from Fisher Scientific), added drop wise in a beaker under vigorous mechanical stirring at room temperature for 5 min [18].…”

“…In this reaction, SBO-derived epoxide is able to directly react with water to form diols because of their high reactivity through cleavage of the oxirane ring [17]. Phosphoric acid not only catalyzes ring-opening reaction but also is chemically involved to become part of the polyol [18,19]. Guo et al [19,20] prepared SPP by using water and a significant amount of polar solvents to obtain high hydroxyl functionality while keeping the final acid value low.…”

Self-Cross-Linkable Anionic Waterborne Polyurethane–Silanol Dispersions from Cottonseed-Oil-Based Phosphorylated Polyol as Ionic Soft Segment

“…Generally, vegetable-oil-based phosphorylated polyols (phospols) are synthesized by ring-opening hydrolysis of epoxidized vegetable oils in the presence of ortho -phosphoric acid . Most of these phosphorylated polyols are utilized in the synthesis of polyurethane foams, , bioelastomers, coatings, and corrosion-resistant waterborne coatings . To date, waterborne polyurethane dispersions prepared with vegetable-oil-based phospols carrying both hydroxyl and ionizable phosphoryl groups have not been reported.…”