Synthesis and characterization of a new compound bearing ketone and hydroxyl groups for preparation of ambient temperature self-crosslinking waterborne polyurethanes

摘要

Anew crosslinker for polyurethane, N-[(1,1 -dimethyl-2-acetyl)ethyll-beta-dihydroxy ethylamino propanamide (DDP), was synthesized by Michael reaction using diethanolamine (DEA) and diacetone acrylamide (DAAM). DDP is a dihydroxyl-containing compound with ketone moiety, which crosslinks during film formation through a reaction between ketone of DDP and hydrazide in water-soluble dihydrazide compound, added upon preparation of waterborne polyurethane. The optimal ratio of DEA/DAAM for Michael reaction, determined by gas chromatography (GC), was of 1.05 mol; highest yields (80%) were obtained with this ratio when the reaction was carried out at 90 degrees C with 12 It of reaction time using acetonitrile as solvent. Experimental conditions of DDP separation from the reaction mixture were predetermined first through thin-layer chromatography, and DDP separation was conducted by column chromatography. DDP with 97% of purity or higher was obtained. The structure of DDP was fully characterized by IR and NMR. The elemental composition and molecular weight of DDP were confirmed by high resolution GC-MS and HPLC-MS, respectively. Polyurethane latexes with DDP and post-added dihydrazide were prepared, and polymer film properties compared with DDP-free latex film. Tensile strength increased with a decrease in elongation in crosslinked polymers. Higher performance in water and solvent adsorptions was also detected. (c) 2007 Elsevier B.V. All rights reserved.