Study On The Surface Double-coated Aluminum Pigments And Its Corrosion Resistance And Mechanical Properties

Aluminum pigment,as one of the important metal pigments,has good metal luster,"different color with angle"effect and other unique beautiful effects,and has the function of delaying coating aging and heat preservation,which was widely used in industrial coatings,automotive coatings,printing ink and plastic processing industry and other fields.However,aluminum pigments are prone to corrosion and loss of luster due to their active chemical properties and large specific surface area,and even lead to the risk of explosion.Therefore,it is necessary to study the corrosion resistance of aluminum pigments and not to destroy their optical properties.In order to improve the corrosion resistance of aluminum pigments,the double-layer coating modification of aluminum pigments was carried out in this paper.the mechanism of the process was explored,and the mechanical properties of aluminum pigments and polyvinyl chloride?PVC?composites were investigated.The details are as follows:1.Aluminum pigments were coated with tetraethyl orthosilicate?TEOS?and silane coupling agent KH570 as binary modifiers by sol/gel method under weak alkaline conditions.Binary modifier TEOS/KH570 can form dense and uniform SiO₂ coating on the surface of aluminum pigment,and its corrosion resistance is obviously better than that of unitary modifier.When TEOS:KH570 is 1:3,the corrosion inhibition efficiency of the prepared aluminum pigment in hydrochloric acid of pH=1 is 61.17%,and the gloss of the surface coated with a transparent SiO₂film is only 7 Gu lower than that of the blank aluminum pigment.2.Firstly,a layer of SiO₂ was coated on the surface of aluminum pigments,and Al₂O₃ was produced by hydrolysis of aluminum isopropoxide to form Al@SiO₂@Al₂O₃ double-layer composite.The results show that Al₂O₃ can form a smooth and dense surface on the surface of aluminum pigments for the reaction time of 4 h at room temperature,resulting in the the surface coating mass fraction of about 10%of SiO₂ and 4%of Al₂O₃.The corrosion inhibition efficiency of the coating is 84.6%in 0.1 mol/L hydrochloric acid,and the tensile strength of PVC resin is increased by 45.77%and elongation at break is increased by 45.77%by adding 0.10 wt%aluminum pigment;When the aluminum pigment is used as 0.1 wt%,the hardness of the PVC resin is increased by 27.05%.3.Aluminumpigmentsaremodifiedwithsilanecouplingagent?KH570?,tetraethylorthosilicate?TEOS?,polymethyl methacrylate?PMMA?and polymethyl acrylate?PMA?organic-inorganic composite coating,and PA@SiO₂@Al/PVC composites were prepared by melt blending with PVC and other additives.The optimal condition for in-situ polymerization to coat PA was to add 0.5 g MMA,0.5 g MA and 0.01 g AIBN at 80? through orthogonal test.,PA/SiO₂/Al composite aluminum pigments have the strongest corrosion resistance,and no hydrogen is evolved in 0.1 mol/L concentrated hydrochloric acid for 48 h,and the corrosion inhibition efficiency is as high as 100%;The compatibility between aluminum pigment and PVC resin is greatly improved after surface coating,and the mechanical properties of PVC can be enhanced.The PA@SiO₂@Al/PVC composite material of elongation at break,tensile strength and hardness as the improvement of surface coating effect showed a trend of increase,compared with the PVC material aluminum not add pigment increased by 123.82%,91.87%and 15.71%;TG shows that the heat resistance of PA@SiO₂@Al/PVC composites is improved;The glossiness also increases with the improvement of the coating effect of aluminum pigments.