The Synergy And Industrial Application Of Two Components Waterborne Polyurethane Coatings

Waterborne polyurethane coatings, given its merits of innoxious, odorless, environment friendness and safety to the human being, now gradually replaces traditional solvent-based coatings. Waterborne polyurethance coatings has mature market share in US and Europe, while in China, it is just started. Even though, the development speed is fast, especially two components waterborne polyurethane coatings. With its almost same properties comparing with solvent based coatings, it has attracted much interest in the world. As a result of joining water, comparing to solvent based polyurethane, Two-component waterborne PU coatings lie in many difficulties. Two-component solvent borne PU coatings must control water, because it is sensitive to NCO component. chemical reaction will take place between them. But two-component waterborne PU coatings treat water as solvent, which is a technical hurdle in its synergy and application. Nowadays, the synergy, production and application of two-component waterborne PU coatings have been developed successfully in US and EU. Bayer, as the technology leader in this market, its 2K PU coatings by acrylic emulsion and hydrophilically-modified polyisocyanate has passed market test and applied widely.In this paper, hydroxyl component-acrylic dispersion was prepared for two-component waterborne polyurethane coatings. The influence of the components of these dispersions on polymerization process such as hydroxyl value, acid value, Tg are tested, by combined with hydrophilically-modified polyisocyanate. Scanning transmission electron microscopy (SEM) was used to characterized the structure and morphology of film, in order to gain excellent waterborne polyurethane coatings; The influence of mixing way, NCO/OH ratio, temperature, humidity was tested, and the reasons of pot life and air bubble were analysized. Finally applications of two-component waterborne polyurethane coatings in different materials were discussed. The indices of two-component waterborne polyurethane coatings by combining acrylic dispersion and hydrophilically-modified polyisocyanate were satisfied compared with solvent-based coatings, and pot life was extended. These problems of two-component waterborne polyurethane coatings were settled by selecting proper techniques and additives in the application such as lower gloss, hardness and bubble limitation of film.Last but not least, the paper use the relavent formulation to wood, construction, and others industries.