Synthesis of Aqueous Dispersions of Functionalized Styrene–Acrylic Copolymers and Preparation of Hybrid Polyurethane–Acrylic Coatings Based on Them

Compositions of aqueous functionalized hydroxyl-containing styrene–acrylic copolymers are developed. Selection of hardeners and conditions for the formation of hybrid polyurethane–acrylic thermosetting coatings with the optimum operational properties is executed. Great attention is paid to the selection of the functionality of the hydroxyl-containing copolymer, as well as ratio of the functional groups of the film-forming agent and hardener during the formation of the coatings. The degree of cure of coatings made of aqueous polymer dispersions is assessed by the concentration of a gel fraction in the samples after extraction, as well as indirectly by the hardness and water absorption of the coatings. It is found that the degree of cross linking of the copolymer expectedly increases from 53 to 88% with the increase in the concentration of OH groups in the copolymer from 1 to 10 mol % and at an equimolar ratio of the functional groups of the hardener and film-forming agent. The highest values of hardness of the coatings and minimum water absorption are observed at a concentration of the functional monomer in the composition of the copolymer in the amount of 3 mol %. Here, the molar ratio of the film-forming agent and hardener by the functional groups should be in a range of 1 : 1.00 to 1 : 1.15. At higher concentrations of the functional monomer in the composition of the copolymer, the lifetime of two-component compositions drastically decreases, and defective less uniform coatings are obtained.