The properties and applications of polyamide-based polyurethanes

Abstract

Abstract A new polyurethane technology utilizing polyamide soft segments was developed for high performance coating applications. Polyamide polyols were designed for urethane systems by controlling compositional features, including hydrogen bonding, polarity, crystallinity and molecular weight. Thus, low molecular weight N-alkylated polyamide oligomers were synthesized from secondary diamines and chain end functionalized to yield primary alcohol end groups. The polyamide polyols had low melt viscosities and good processability in waterborne polyurethane dispersions. Coatings of waterborne polyamide urethane dispersions were made and characterized by industrial coating applications tests and compared to polyether, polyester and polycarbonate polyol-based urethanes. We found that urethanes with tertiary polyamide segments show a unique set of properties and high performance in coating applications. Coatings of polyamide polyurethanes have excellent abrasion resistance coupled with high hardness, good hydrolytic stability, improved barrier properties and strong adhesion to various polar substrates. Polyamide polyols can also be used to control film formation properties in waterborne dispersions to achieve gloss control and create matte finishes.