A novel bulk-matte water-borne polyurethane coating composite
The coating composite was comprised of a siloxane-containing water-borne polyurethane (SPU) resin and a crosslinked water-borne polyurethane (CPU) resin. The CPU resin was mainly responsible for fabricating the micro-rough surface of the film, which was achieved by a crosslinking reaction between the water-borne polyurethane and bisphenol A-type epoxy E-44 resin. The SPU resin was used to improve the comprehensive properties of the film, which was ascribed to the addition of silane coupling agent KH792. Compared with traditional matte coatings, this coating composite made it possible to avoid high loadings of matting agent and to arrive at highly flexible low-gloss finishes.
Gloss values even at high angles of incidence
Gloss levels of as low as a few tenths of a percent, even at high incidence angles, have been achieved with zero loading of extraneous dulling agent. The chemical structures of the SPU and CPU resins were characterised by FTIR-ATR and NMR spectra. The micro-rough topographies and surface rough degrees of the SPU, CPU and their 50%/50% composite films were measured by SEM and MSP, respectively. The particle sizes and particle morphologies of the SPU and CPU resins were imaged by TEM. Finally, the comprehensive properties of the SPU, CPU and their 50%/50% composite resins were evaluated, including the water contact angle, film transparency, tensile strength and storage stability.
The study is published in: Journal of Coatings Technology and Research September 2018, Volume 15, Issue 5, pp 993–1002.