Preparation Of Waterborne Colored Aluminum Pigments And Its Application In Polyacrylic Acid Coatings

As a kind of metallic pigment with several advantages of metallic flash characteristics,flop characteristics,low price and other excellent properties.aluminum pigment is widely used in plastic spray-free industry,industrial coating.automotive topcoat coating,decorative coating and ink printing industry.Colored aluminum pigments are favored for their excellent properties and characteristics of aluminum pigment and bright colors..With the development of society,the single silver-white aluminum paste products have been unable to meet the aesthetic requirements of people,the industrial production and application of colored aluminum pigment is bound to be a trend.In addition,due to the scarcity of colored aluminum pigment products in the current market,the rarity is the most expensive,so the market price is much different from that of ordinary silver white or silver grey aluminum paste products,and the market potential of color aluminum pigment in the future will be greater and greater.Although aluminum pigments are ideal for use in oil-based coatings,aluminum pigments are prone to corrosion reactions in aqueous coatings torelease hydrogen gas and cause unsafe factors.Therefore,only by antiseptic modification of aluminum pigment can waterborne aluminum pigment be prepared.In this paper,two kinds of water-based colored aluminum pigments were prepared by chemical grafting method and in-situ copolymerization method,and these two water-based color aluminum pigments were successfully applied to water-based acrylic paints.The contents are mainly divided into the following aspects:(1)Using a sol-gel method,firstly,TEOS and APTES were used for synergistic hydrolysis,the surface of the aluminum pigment sheet is coated with a dense layer-NH2 functional group of SiO2 organic-inorganic hybrid membrane,then using 5-sulfosalicylic acid and ferric ion to form two ligands in the environment of pH 4-9 to obtain the principle of red dye,a red 5-sulfosalicylic acid complexed iron dye was synthesized and finally grafted onto the surface of the aminated aluminum pigment by chemical grafting to obtain a Red colored aluminum pigment.The modified aluminum powder and the colored aluminum powder were characterized by means of FTIR,SEM,XPS,TGA and particle size,and the grafting success of the colored aluminum pigment was confirmed.The corrosion resistance of the aluminum pigment samples before and after the coating modification and before and after the coloring were analyzed and compared using the method of collecting hydrogen.(2)Using sol-gel method,a layer of organo-inorganic SiO2 hybrid film with propylene double bond was formed on the surface of aluminum pigment film by synergistic hydrolysis of ethyl orthosilicate and methylacryloxypropyltriethoxysilane.Then an amide reaction of disperse orange 11 dye and acryloyl chloride is used to synthesize an orange small molecule dye monomer(AM)which can be polyadded.Finally,the small molecule dye monomer and the acrylic monomer and the propylene double bond on the surface of the aluminum pigment are together.The in-situ copolymerization reaction occurs under the action of an initiator,and a polymer having both an aqueous group and a dye is grafted on the surface of the aluminum pigment.In the preparation of the colored aluminum pigment,an aqueous system of the aluminum pigment product is also obtained.In response to the policy requirements at the same time for the water market to add a water color aluminum pigment products.FTIR,SEM,XPS,TGA and other characterization methods were used to compare the chemical functional group changes,chemical element changes and content changes and chemical structure changes of aluminum pigments before and after modification and before and after coloring,which confirmed the success of in-situ copolymerization.(3)Two water-based color aluminum pigment products were separately applied to the water-based acrylic paint.In the experiment,a four-sided applicator was used to prepare a metal-effect paint coating film on a standard plate at a fixed thickness.Then,the properties of gloss,pencil hardness and adhesion of the coating film of aluminum pigment products added with water-based acrylic coating under the content gradient of 0%,0.6%,0.8%,1.0%,1.2%,1.4%and 1.6%were investigated.From the graphs of performance,we found that adding amount of aluminum pigment products too high or too low all have certain influence on the performance of the coating.It is found that the properties of the coating to achieve optimal combination when the amount of aluminum pigment products is 1.2%.Thus,we choose 1.2%as the critical value of waterborne acrylic coatings for aluminum pigment products.In addition,in addition to colored aluminum pigment decreased gloss of the coating film,the other film properties such as pencil hardness,adhesion,etc.,are tends to increase,which may be resulted by the surface of the organic structure on surface of the double-layered structure colored aluminum pigment product and the compatibility with the coating matrix has increased.