Aqueous dispersions with bimodal particle size distribution

摘要

Aqueous, self cross-linked unicomponent polyurethane dispersion with a bimodal particle sizes distribution exhibiting two separate maxima, where: the portion of the fine particles of the cross-linked particles is 1-100 nm, the portion of the coarse polyurethane-polyurea particles is 10-400 nm and the weight ratio of the fine and coarse portion is 0.5/99.5 to 10/90. Independent claims are included for: (1) a method for the preparation of the unicomponent polyurethane dispersion comprising dispersing the polyurethane-polyurea particles of the coarse portion, water and fine portion of the dispersion, where ratio of the water and fine portion of the dispersion is 1/1 to 1/20; and (2) baking lacquer comprising the aqueous, self cross-linked unicomponent polyurethane dispersion.