Waterborne Polyurethane from Polycaprolactone and Tetramethylxylene Diisocyanate: Synthesis by Varying NCO/OH Ratio and Its Characterization as Wood Coatings

Abstract

Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was carried out in flowing nitrogen atmosphere. The PUD's preparations are free of NMP (n-methyl pyrrolidone), a toxic processing solvent generally used during the preparation of PUD's. The performance of the synthesised polyurethane dispersions with varying NCO/OH molar ratio was tested on wood surface. The physical, chemical, thermal and mechanical properties such as viscosity, particle size, chemical resistance, thermal stability and taber abrasion of applied polyurethane dispersion were carried out as a function of NCO/OH molar ratio. The PUD's preparation with NCO/OH ratio of 1.4 or 1.6 showed better performance as a wood finish and the results are described in the present study.

Developments in aqueous polyurethane and polyurethane-acrylic dispersion technology. Part II. Polyurethane-acrylic dispersions and modification of polyurethane and polyurethane-acrylic dispersions

“…More details on various coating applications of APUD and APUAD can be found in e.g. [19,53,55,59,71,[93][94][95][96][97][98][99][100][101][102][103][104]. Other important current and potential applications of APUD and APUAD include, inter alia:…”

Polydimethylsiloxane containing waterborne hydrophobic polyurethane coatings with good adhesion to metals: Synthesis and characterization

“…In order a polyurethane to be synthesized in water media, different strategies must be designed due to the reactivity of the water with the isocyanate [2]. Among them, the acetone process is one of the most employed [3][4][5]. This methodology implies 3 reaction steps: in the first step, the polyurethane is synthetized with isocyanate, polyols and dispersant agent in acetone, in the second, water is added to perform "phase inversion" process.…”