Preparation And Properties Of Rosin-based Coatings

Alkyd resins are widely used in anticorrosive coatings because of their good adhesion,flexibility,solvent resistance,low cost and abundant sources.However,traditional alkyd resins also have many defects,such as long drying time of paint film,poor water resistance and mostly contain volatile organic compounds（VOC）.If VOC is emitted during the painting process,it will seriously damage the ecological environment and threaten human health.Rosin is a kind of natural heat renewable resource,rosin used in alkyd resin not only can slow down the gelation of materials,and make alkyd resin soluble in aliphatic hydrocarbon solvent,but also can shorten the drying time of paint film,increase of coating hardness,improve of water.In this thesis,three alkyd resin coating were prepared by using Zn-abietate,fumaropimaric Acid（triethylamine）and Ni-MOFs as corrosion inhibitors.The optimum content of corrosion inhibitor was determined.The mechanical properties and corrosion resistance of alkyd resin composite coating were studied as follows:（1）A rosin-based alkyd resin anticorrosive enamel paint was prepared using the drying long oil alkyd resin as the film-forming substance,Znabietate as corrosion inhibitor and other additives.Six kinds of composite coatings with different contents were prepared by spraying method.The anticorrosive properties of enamel paints were analyzed by Tafel polarization curve,AC impedance technique and salt spray fog test.The results of Tafel polarization curve and electrochemical AC impedance show that the enamel paints have the better corrosion resistance after addition of Zn-abietate.The anticorrosive properties of coatings are the best when 0.25% of Zn-abietate was added into the formula of enamel paints.（2）A rosin-based alkyd resin anticorrosive enamel paint was prepared using the drying long oil alkyd resin as the film-forming substance,fumaropimaric Acid（triethylamine）as corrosion inhibitor and other additives.Six kinds of composite coatings with different contents were prepared by spraying method.The anticorrosive properties of enamel paints were analyzed by Tafel polarization curve,AC impedance technique and salt spray fog test.The results of Tafel polarization curve and electrochemical AC impedance show that the enamel paints have the better corrosion resistance after addition of Fumaropimaric Acid（triethylamine）.The anticorrosive properties of coatings are the best when 0.3% of Fumaropimaric Acid（triethylamine）was added into the formula of enamel paints.（3）Three kinds of composite coatings were prepared by adding acrylpimaric acid（ethylamine）,acrylpimaric acid（ethylenediamine）and fumaropimaric Acid（triethylamine）into alkyd resin as corrosion inhibitors,and their stability was studied.Through water absorption test,electrochemical test and salt water resistance test,the coating with acrylpimaric acid（ethylenediamine）has the best corrosion resistance,indicating that with the increase of N and S element content in the molecule,the greater the cross-linking effect,the stronger the densification of the coating,but the electronegativity of N and S elements is strong,when the content is too large.It is also vulnerable to the attack of water and acid in the corrosive medium of the external environment,which also reduces its corrosion resistance.（4）A flake-like Ni-based metal-organic framework materials（NiMOFs）were synthesized by hydrothermal method.The morphology and structure of Ni-MOFs were characterized by SEM and XRD,respectively.A rosin-based alkyd resin varnish was prepared using fumaropimaric Acid（triethylamine）（FPAA）and the long alkyd resin（LAK）as the film-forming substance,the as-prepared Ni-MOFs as a dopant.The as-prepared varnish were coated onto the carbon steel electrode and tinplate.The properties of the coatings were investigated by Tafel polarization curve,electrochemical impedance spectroscopy（EIS）,salt spray test and hardness test.The results showed that the properties of alkyd resin varnishes were significantly improved by Ni-MOFS hybrid materials compared with those without NiMOFs.The best anti-corrosion performance was obtained by adding 0.3%Ni-MOFs varnish.