Paint Aluminum Surface Coating And Paint

Aluminum flakes(Aluminum pigments) as one of metal powder pigments is used very broad now. Its morpHology is squama, Diameter is between about 3-70μm and the ratio of diameter and thickness between about 60-150.It has been used in Construction, automotive, printing ink and solvent-borne metallic paints due to its metallic appearance and "flop-effect". In recent years, With the increased of environmental protection awareness and improvement of environmental regulations, The solvent-borne metallic paints has gradually been replaced by waterborne coatings. But the resulting problem is when Aluminum pigments is used in waterborne coatings, Aluminum pigments and water react and evolve much hydrogen, so it bring much danger to production and application. Therefore, it is necessary to treat the Aluminum pigments first before they are applied in waterborne coatings.This paper first used traditional sol/gel method to treat the Aluminum pigments, by using TEOS as precursor to prepared inorganic-nano-SiO2 encapsulated aluminum pigments. By a large number of experiments to found that the best experimental conditions. Use 2.0g Aluminum pigments, when the molar ratios of Al/TEOS and H2O/TEOS are 5 and 30 respectively, the volume of ammonia is about 3%, the temperature an time of the reaction are 40℃and 6h respectively. With this approach, compact SiO2 films on the surface of aluminum pigments can be found,thus greatly improving the alkali resistance of the pigments, with little hydrogen being evolved by dipping it in an alkaline medium with a pH value of 11 for long time. But the gloss of the aluminum pigments is greatly weakened in the slo/gel precess, decreased about 30%.Encapsulated aluminum pigemens were prepared by modified sol/gel method using TEOS and VTES as precursors. By a large number of experiments to found the best experimental conditions. Use 2.0g Aluminum pigments, the volume of TEOS and VTES are 3mL and 2mL respectively, the total system volume is 110mL, the volume of Ammonia and water are 6mL and 5mL respectively, the temperature an time of the reaction are 50℃and 6h respectively. With this approach,compact coating films on the surface of aluminum pigments can be found,thus greatly improving the alkali resistance of the pigments,with little hydrogen being evolved by dipping it in an alkaline medium with a pH value of 11 for long time,and the gloss of the aluminum pigments is great improved then SiO2/Al,only decreased about 10%.Finally,application of the cncapsulated aluminum pigments prepared in the expriment in solvent and waterborne coatings were studied. By experiments, when the encapsulated aluminum pigments are used in solvent-borne metallic paints, two encapsulated aluminum pigments paint are very good at the acid and alkali solution, but the SiO2/Al paint have some granule on its surface and the gloss is very bad. When they were used in waterborne coatings, its comprehensive performance have been approached similar products abroad, only little problem on hiding and anti-deciduous.These studies are greatly promote the developing of our country waterborne coatings.