Synthesis of Environmentally-Friendly Polyurethane Dispersions Based on Soybean Oil-Derived Polyols and their Applications in Advanced Water-Based and UV-cure Coatings.

摘要

Polyurethane dispersions (PUD) have established themselves as most versatile polymeric binder in coating, adhesive, sealant, and elastomer industries. Like any other polymers, PUDs also have certain limitations, such as hydrolytic stability, water resistance, and oil resistance. In order to develop these properties, two different polyol families were synthesized. The first polyol can be used in ambient curable systems, and the second can be utilized in ultraviolet radiation cure coatings. For ambient curable systems polyether chemistry based soy-polyol was developed from epoxidized soy fatty acid methyl ester (ESFAME). The cationic ring opening of oxirane oxygen groups from ESFAME resulted in polyol with average hydroxyl number 88 mgKOH/g and number average molecular weight 1517.;The indigenous soy-polyol was used as soft segment polymeric chain backbone of aqueous PUD. The PUDs with varying soft segment to hard segment ratios were developed and characterized for film properties, surface properties, chemical resistance, and thermal properties. The PUD (55% bio content) with reasonable aforementioned properties was utilized for further developmental work, where hydrophobicity and oleophobicity of the coatings were improved to meet the goal of the project. Siliconated (Si) and fluorinated (F) polyol was utilized with indigenous soy-polyol, and 7 different polyurethane polymeric chains were fabricated with varying Si and F concentration. The topographical morphologies of these PUDs were monitored with AFM, and the hydrophobicity was monitored with contact angle instrument. All other basic film properties, water and oil resistance properties were thoroughly discussed. Also, the PUDs were self-crosslinked with carbodiimide and excellent water resistance and oil resistance coatings were achieved from this research.;For ultraviolet curable coatings, novel hydroxylated acrylic epoxidized soybean oil was synthesized from commercially available epoxidized soybean oil (ESO). It was characterized for viscosity, hydroxyl number, iodine number, molecular weight, FT-IR, and NMR studies. The UV-cured coating films were designed from this indigenous acrylated ESO (AESO) and they were tested for pencil hardness, pendulum hardness, impact resistance, adhesion strength, and thermal properties. In order to further improve the mechanical properties, AESO was used in dual curable coatings. The developed instant radiation curable and ambient curable coatings resulted in excellent chemical resistance, optimum mechanical and thermal properties. The advantage of hydroxyl groups of AESO was taken to develop 9 different UV-curable PUDs. The coating properties were characterized based on constant crosslink density, increasing crosslink density. Once again, topographical studies were conducted with AFM, and contact angle studies were used to determine the UV-PUDs water resistance.