Environment-friendly Automotive Coatings

The GMA-MMA-BA terpolymer of GMA acrylic resins was synthesized by solution polymerization and suspension polymerization method, respectively. In this thesis, the effects of the synthetic method and the ratio of raw materials on the properties of the products were studied. The structure of the products was analyzed by FT-IR spectra, then, the epoxy equivalent, glass transition temperature and molecular weight of products were tested, respectively.Meanwhile, using the synthetic resin by ourselves with the dibasic acid prepared GMA acrylic powder coating. Influence of the film’performance about the resin molecular weight, the baking temperature, and the content of the curing agent were studied, corrosion resistance and mechanical performance test was conducted on the film.Toluene was used as solvent, the amount of initiator was from3to5%, the GMA acrylic resins were prepared by solution polymerization. The products of resin molecular weight of3000to7000, epoxy equivalent weight of440～590g/eq, the Tg of50.6to55.1℃, and the results comply with performance requirements of GMA acrylic powder coating.Deionized water was used as the dispersion medium, the initiator agent and chain transfer agent is used in an amount ratio of greater than5:2, the molecular weight (<9000) of obtained resin, by suspension polymerization, was to meet the requirements of the powder coating with the resin properties, and molecular weight distribution is narrow. The average particle size of the resin product was58μm, wherein the particle size which is less than30μm have10%, a particle size of50%was less than54μm, and the90%was less than92μm, its particle size and the distribution was in line with the particle size and distribution of range general powder using, favoring the latter part of the coating preparation.Using the GMA acrylic resin which was synthesized by ourselves and the dodecanedioic acid as a curing agent, was prepared the GMA acrylic powder coating. The GMA acrylic resin molecular weight was in the range of from4000to6000, the proportion of the epoxy groups and carboxyl functional groups in the system was1:1, and the curing temperature was150to160℃, the powder system with the better leveling, and the appearance of the coating is smooth. And the resulting the coating acid resistance (10%H2SO4) was more than70h, alkali resistance (5%NaOH) was more than90h, salt water (5%NaCl) was more than110h, the pencil hardness of2H, adhesion to reach the national standard of0, flexibility impact strength was3mm, and the30cm being rushed was through. Corrosion Resistance and mechanical properties have reached the national standards of the automotive industry. Has a positive role in promoting the application of the biological production of long-chain dicarboxylic acids.The paper also studied the combination of short-chain dicarboxylic acid as a curing agent with GMA acrylic resin powder coating film properties, and found that the film properties of dodecanedioic acid curing agent in strength, flexibility and impact resistance resistance performance and other aspects there are obvious gaps.