The Synthesis And Development Of Styrene-Acrylicacid Waterborne Anti-Corrosion Coatings

Waterborne coatings can effectively decrease the release of organic volatile compounds,which helps to improve environment.However,several problems exist in the process of using waterborne coatings on steel that includes flash-rust,cavities on coating,residual of emulsifying agents etc.In this paper,different methods have been used to improve the properties of styrene and acrylic acid based polymer emulsion.By adjusting dosage and kinds of monomers,adding corrosion inhibitors,finally we obtained the waterborne coating with good properties that could be steady in water for 15 days,in saline water for 15 days.In the mean time,we chose 8 kinds of organic phosphate monomer to find the best one through experiments and properties tests.1.Synthesis of polymer emulsion(1)In this paper,we use styrene and butyl acrylate as primary monomers,PP-70 as organic phosphate monomer.In the process of step method of emulsion polymerization,we also added DAAM as cross-linking monomer,chose SE-10N and TX-30 as emulsifying agents with the dosage of 1.5%-1.8%.Finally,we obtained steady emulsion with 40%solid content and 130nm average particle size.(2)By adjusting the solid content,we found that emulsion with 40%was better than 45%and 50%.When we used 0.3%APS as initiator under the temperature of 80 ?,the emulsion solid content reached the design value.2.Coating properties test results(1)Using BYK-019 and BYK-024 as anti-foaming agents in the weight proportion of 2:1.The dosage of agents is 0.3%of the emulsion.The coating is smooth without cavities on the surface.(2)Using environmental-friendly waterborne Halox-515 as anti-corrosion agent.The dosage is 1.5%-2.5%,then we got stainless coating after spraying the varnish.(3)Under the same condition,including monomers and emulsifying agent,9 kinds of organic phosphate monomers have been evaluated to find the best one.After experiments,we chose PP-70 as the functional monomer which gave coatings good adhesive force property and anti-corrosion property.(4)Results of varnish resistance properties to chemicals.Using DAAM and ADH as cross-linking monomers,when the weight proportion is 0.5:1,dosage of PP-70 is 2%,the coating owns the best properties.There was no bubble on the surface in the distilled water for 15 days.The steel plates didn't rust in the salt water for 15 days and 30 days in sodium hydroxide water.