The Synthesis of Functionalized Water-Based Styrene–Acrylic Copolymers and Preparation of Hybrid Polyurethane–Acrylic Coatings

Abstract

The aim of the work is the development of a composition of water-based functionalized hydroxyl-containing styrene–acrylic copolymers as well as selection of hardeners and conditions of formation of hybrid polyurethane–acrylic thermosetting coatings with the optimum operational properties. To achieve the set goal, great attention is paid to the selection of the functionality of hydroxyl-containing copolymer as well as the ratio of the functional groups of the film-forming agent and hardener during the formation of the coatings. The degree of cure of the coatings from aqueous polymer dispersions is estimated by the concentration of the 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 crosslinking of the copolymer expectedly increases from 53 up to 88% with the increase in the concentration of OH groups in the copolymer from 1 up 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 of 3 mol %. Here, the molar ratio of the film-forming agent and hardener by functional groups should be in a range of 1 : 1.00 to 1 : 1.15. The lifetime of two-component compositions sharply decreases at higher concentrations of the functional monomer in the composition of the copolymer, and defective and less uniform coatings are obtained.