1K Pur dispersions to 2K Waterborne dispersions

By Makoto Nakao

This article discusses the physical properties, as defined in American Architectural Manufacturers Association (AAMA) 615-13 specification,³ of a newly developed 1KPUR dispersion (hereinafter called “Next-gen 1KPUD”) that demonstrates comparable performance properties to 2KWB coatings used to paint residential vinyl windows today.

EXPERIMENTAL
To increase the performance of a 1KWB PU to the level of a 2KWB PU, an intensive development program was undertaken. Its goal was to develop a 1KWB PU with higher film hardness (e.g., >2H pencil gouge hardness) and with superior chemical resistance (e.g., detergent, nitric acid, and mortar).

The study examined various kinds of high molecular weight polyol, different isocyanate monomer, various levels of hard block content, chain extension, neutralization, and solubilizing agents. The development program succeeded, identifying a 1KWB PU dispersion with comparable performance to a 2KWB PU. The novel 1KWB PU dispersion, Next-gen 1KPUD, was synthesized using a prepolymer mixing process.4 Key properties of this PUD are listed in Table 1.