Synthesis And Curing Of Acrylic Resin For Powder Coatings

Powder coating curing process is an important step of electrostatic spraying, its effect will directly influence the surface appearance, mechanical properties and use value of spray products. Exploration the characteristics of the cured resin and curing kinetics provide a important theoretical basis to optimize the cured product mechanical properties and to determine electrostatic spraying curing process. The main research work of this paper are:In this thesis, GMA acrylic resins、carboxyl acrylic resin and hydroxyl acrylic resin were composited from the way of free radical solution polymerization, using GMA, AA, BA, MMA and HEA as monomers. After the polymerization, succinct anhydride and glutaric anhydride were reacted with hydroxyl groups in hydroxyl acrylic resin to get acrylic resins that carboxyl groups on the different length of flexible branched chain.The polymerization temperature, the amount of solvent, the amount of initiator and polymerization time on the resin properties were studied, the GMA acrylic resin and carboxyl acrylic resin which comply with the requirements of powder coatings were synthesized. The ratio of GMA acrylic resin monomer:GMA:BA:MMA=25: 15:60, epoxy value is 0.14, Tg is 55℃, softening point is 109℃; The ratio of carboxyl acrylic resin monomer:AA:BA:MMA=15:64:21, acid value is 108mgKOH/g, Tg64.3℃, softening point is 122℃.The curing reaction between GMA acrylic resin and carboxyl acrylic resin. The curing behavior of carboxyl acrylic resin/GMA acrylic resin and carboxyl acrylic resin/TGIC two systems which add 2-methyl imidazole, zinc MZ, benzyl trimethyl ammonium chloride, Hexadecyl trimethyl ammonium bromide, and zinc acetylacetonate were studied. The apparent activation energy were calculated by means of Kissinger methods. Among them, 2-methylimidazole can minimize the apparent activation energy 71.3kJ/mol, the catalytic effect is prominent.The influence factors of carboxyl acrylic resin/TGIC curing reaction. The results show that the larger molecular weight carboxyl acrylic resin, the lower the temperature of the curing reaction; with the epoxy/carboxyl group molar ratio is increased, the curing peak temperature shifts to lower temperature direction; with the increase of the amount of curing accelerator, the curing peak temperature moves to lower temperature.Curing analysis of acrylic resin which carboxyl branch located on the different length of flexible branched chain. Curing process and thermal stability of systems were studied using DSC and TGA analysis. Results show that the carboxyl as closer to the main chain, the apparent activation energy of the system is far lower, is helpful to reduce the curing reaction temperature, the initial decomposition temperature of cured product were 368℃,372.4℃.Powder coatings were prepared both Acrylic resins that carboxyl groups were generated by succinic anhydride, glutaric anhydride reaction with hydroxyethyl acrylate and TGIC. The impact strength of the coating films are increased, the bending strength and the adhesion of the coating to improve, indicating that the coating film performance tests show that the introduction of a flexible side chain can improve the impact resistance properties of the film.