Preparation of Silicone Modified Waterborne Polyurethane Emulsion.

A silicone-modified waterborne polyurethane emulsion (Si-WPU) was prepared by carbon dioxide binary alcohol (PPC), polypropylene glycol, poly-1,4-butylene adipate glycol, 4-methyl-m-phenylene diisocyanate, 2,2-bis(hydroxymethyl)propionic acid, N- [3-(trimethoxysilyl)propyl] ethylenediamine (KH 792) and triethylamine as the main raw materials. The influence of R(the mole ratio of isocyanate to hydroxyl group), the type and content of soft chain segment as well as the amount of KH 792 on the appearance, particle size and stability of Si-WPU emulsion were studied. The influence of mechanical strength, adhesion, water absorption, water contact angle and heat resistance of the cured Si-WPU film was also systematically studied. The results showed that when R was 1. 67, PPC was the soft-chain segment with an addition volume of 75wt%, and KH 792 was 3. 5wt%, Si-WPU emulsion was pan-blue with low viscosity, low particle size and good stability, i. e., the viscosity was 313 mPa·s and particle size was 213 nm. In addition, the Si-WPU film showed better comprehensive performance, with hardness of 2 H, tensile strength of 53. 83 MPa, fracture elongation of 1 465%, adhesion grade of 4B, water contact angle of 93. 5° and water absorption rate of 2. 65%. A novel preparation route has been provided for high-performance and environmentally friendly waterborne polyurethane coating. [ABSTRACT FROM AUTHOR]