Preparation And Characterization Of Low-gloss Waterborne Polyurethane Coatings

Leather matting finishing agents currently mainly add silica matting agents into polyurethane emulsion to achieve matting performance. By adjusting the formulations of polyurethane emulsion, low-gloss polyurethane dispersions without addition of matting agents can be prepared, so as to overcome poor stability and poor scratch resistance of polyurethane containing matting agents. In this paper, with the terminal hydroxyl polydimethylsiloxane, polyethylene glycol, toluene diisocyanate, dimethylolpropionic acid, dibutyltin dilaurate, a series of water-based polyurethane extinction emulsions were prepared. The main findings are as follows:(1) Optimized the preparation process of copolymer matting waterborne polyurethane: at 90 ℃, react terminal hydroxyl polydimethylsiloxane, polyethylene glycol, toluene diisocyanate and dibutyltin dilaurate catalyst together for 4h. Cool the performed polymer to 50 ℃, then add quantitative dimethylolpropionic acid and solvent such as tetrahydrofuran, heat to 70 ℃ and react for 2h. Cool polymer to room temperature, add quantitative triethylamine and deionized water to make emulsions.(2) Copolymer matting aqueous polyurethane under the conditions of R = 1.2, DMPA mass fraction of 6%, PEG molecular weight 1000, PEG / PDMS molar ratio = 1: 3, catalyst mass fraction of 0.5%, neutralization degree 100%, latex solid content of 20%, gets the best overall performance, 60 ° gloss of 3.3, achieving excellent matting performance.(3) Blend PDMS-PU and PEG-PU to prepare blending matting WPU. When the mass fraction of PDMS-PU is 25%, the blending WPU gets the best overall performance, 60 ° gloss of 5.2, in line with matting standards.