Bio-based 1,5-Pentanediol as a Replacement for Petroleum-Derived 1,6-Hexanediol for Polyester Polyols, Coatings, and Adhesives

Amorphous and semi-crystalline polyester polyols based on a novel, low cost, bio-based 1,5-pentanediol (Bio-PDO)were synthesized and formulated into solvent-borne coatings andhot melt adhesives. Bio-PDO may provide a lower cost, moresustainable, and non-petroleum-based alternative to polyols basedon 1,6-hexanediol (HDO). The polyester polyols were charac-terized for end group composition, monomer incorporation, andthermal transitions. Bio-PDO-based coatings exhibited perform-ance, including hardness,flexibility, adhesion strength, and solventresistance, similar to the coatings based on petroleum-derivedHDO. Bio-PDO-based adhesives exhibited lower green strength(initial adhesion strength) and longer open time (workable time tobond substrates) than HDO-based adhesives. The effects ofcommon bio-based impurities, including lactones and mono-alcohols (delta-valerolactone and tetrahydrofurfuryl alcohol as examplesof impurities), on polyester polyols were investigated. Hydroxyl functionalities of polyols were controlled by the excess diols inmonomer feeds and were not impacted largely by the delta-valerolactone levels. High-level tetrahydrofurfuryl alcohol terminated thepolyester ends with unreactive functionality. Deleterious effects on polyol hydroxyl functionality are not expected at the low impuritylevels (<2 wt %) found in leading bio-PDO processes