Synthesis of polyether polyols with epoxidized soy bean oil

• Triflic acid was found to be a very effective catalyst for preparing ESBO polyether polyols.
• As alcohol concentration relative to ESBO is reduced, higher molecular weight polyether polyols are produced in a controlled fashion.
• These higher molecular weight polyether polyols can be cured with conventional crosslinkers to give reasonable film properties.
• ESBO polyether polyols can be grafted with acrylic monomers to produce solvent and water borne co-polymers with cured film properties equivalent to a commercial epoxy control.

Epoxidized soy bean oil (ESBO) polyether polyols have been prepared and evaluated as potential bio-renewable replacements for bisphenol A based epoxy coatings. Zinc triflate was found to be more efficient in catalyzing the ESBO hydroxyl reaction than methanesulfonic acid or boron trifluoride etherate. With an excess of n-butanol, ESBO epoxide groups ring open to give the expected polyether polyol, but as the n-butanol concentration is reduced, dimers, trimers, and higher molecular weight analogs of the triglycerides appear. Weight average molecular weight can be increased in a controlled fashion to over 10,000 Da by using trimethylolpropane (TMP) in place of n-butanol. The addition of solvent reduces molecular weight of the polyether polyol, at an equivalent TMP level while still allowing good reaction control. These polyether polyols can be cured with phenolic resins, but solvent and blush resistance, adhesion, and wedge bend flexibility are inferior to a commercial bisphenol A epoxy control.ESBO polyether polyols were then grafted with an acrylic monomer mix that included methacrylic acid using initiators with high grafting efficiencies. Neutralization with a base allowed the formation of stable aqueous dispersions. However, use of an initiator with a low grafting efficiency under the same conditions did not produce a stable aqueous dispersion. A simple blend of a pre-formed acrylic with the ESBO polyether polyol likewise did not form a stable dispersion. Solvent borne and water borne ESBO polyether polyol acrylic grafted co-polymers were cured with phenolic, benzoguanamine and melamine crosslinkers. Films were comparable to a commercial BPA epoxy control having excellent solvent and blush resistance, good adhesion, and good flexibility.