Preparation And Performance Of Optically Variable Water-Based Color Aluminum Pigment

Aluminum pigment is widely used in coatings,printing inks and textile industries as an important metal powder pigment.With the gradual improvement of government environmental regulations and the enhancement of human's awareness of environmental protection,traditional organic coatings are gradually replaced by water-based coatings.However,the aluminum pigment wtih single color is not enough to meet the needs of market applications,aluminum pigment has the problems in anti-corrosion performance and poor compatibility with the substrate in water-based coatings due to its own metal properties.Although the traditional method that ethyl orthosilicate is hydrolyzed on the surface of aluminum pigment to form SiO₂for coating and modificating can significantly improve the corrosion resistance of aluminum pigment,but SiO₂ has poor compatibility with resin,so it is difficult to uniformly disperse in coating systems.At the same time,the modified SiO₂ coating will reduce the color saturation and optically variable of aluminum pigments.According to the above problems,this paper has done the following research.?1?Aluminum pigment was modified by dopamine and then two kinds of colored aluminum pigments of amino aluminum orange pigment and mercapto green aluminum pigment were prepared by chemical grafting two kinds of dyes including disperse orange 11containing amino group and brilliant green GB containing thiol group.Then the analysis of surface micro structure and chemical structure of the aluminum pigment were characterized by FTIR,SEM,EDS,XPS,TGA and particle size analyzer.The experimental results confirmed that dopamine formed a polydopamine coating layer containing a quinone structure on the surface of the aluminum pigment and successfully achieved chemical grafting with the dye.The surface coating layer of aluminum pigment is uniform and dense and with the small thickness.?2?The effects of four factors including pH environment of buffer solution,mass ratio of aluminum pigment to dopamine to dye,solvent volume ratio of buffer solution to ethanol to reaction time were investigated by designing orthogonal experiments and the acid resistance of colored aluminum pigments under different reaction conditions was tested.The results of hydrogen evolution test show that both the amino orange aluminum pigment and mercapto green aluminum pigment prepared by dopamine modified graft coloring have good acid corrosion resistance and the amount of hydrogen evolution is 12 mL and 16 mL respectively.The colored water-based paint are prepared by added two kinds of colored aluminum pigments to the water-based acrylic resin paint and the coating film is colorful,which has higher color saturation and more excellent optically variable properties compared to traditional aluminum pigments prepared by SiO₂ coating and modification.The color saturation of the aminated orange aluminum pigment at 110^�is 50.51.?3?The contact angle test results show that the contact angles of the two acrylic pigment coating films colored by dopamine modified grafting are smaller than the unmodified aluminum pigments,which the contact angles of the coating films of aminated orange and thiolated green aluminum pigment coatings is 56.2^�and 59.8^�respectively.It shows that the surface of aluminum pigment obtained by dopamine modification and grafting and coloration of amino and mercapto dyes has good hydrophilicity which can improve the compatibility of aluminum pigment with water-based acrylic resin matrix.