Study On Surface Modification Technology Of Titanium Dioxide

Titanium dioxide,a new type of inorganic function material, has widely application in resent years as because of its excelled properties.If Titanium dioxide without surface modification is directly used in some organic materials systems such as paint, plastic, rubber, Titanium dioxide is difficult to disperse because of mismatched performance. Moreover, it will accelerate the organic materials aging for its photochemical activity. Therefore, it must be treated with inorganic and organic surface modification. Inorganic surface modification is mainly used to remove its photochemical activity, while organic surface modification aims to improve the dispersion of titanium dioxide in organic materials systems.The research result and content of this thesis includes the following five aspects.(1) Research on dispersion of titanium dioxide before surface modification.The dispersion testing method is studied through settlement experiment, absorbance and Zeta electric potential experiment in this work. The dispersion and stabilization of TiO2power in suspension under different pH values, different dispersant and the amount of dispersant were investigated. The experimental results indicate that when pH is9-10, the dispersion TiO2using Sodium hexametaphosphate (0.4%, weight ratio) as dispersant in aqueous solution is stable.(2) Surface modification of titanium dioxide by alumina.The surface of titanium dioxide was coated by alumina through chemical deposition using Al2(SO4)3and NaOH as film coating. The influences on weatherability, oil absorption, acid soluble rate and hiding power of the amount of alumina, reaction pH, time and temperature were investigated; the products were characterized by TEM, XRF and XRD. Which the best coating condition is formed, that is, the coating temperature is85℃,coating pH is9～11,coating time is3hours, coating dosage is4%.(3) Surface modification of titanium dioxide by silicon.The surface of titanium dioxide was coated by silicon through chemical deposition using NaSiO3and H2SO4as film coating. The influences on weatherability, oil absorption, acid soluble rate and hiding power of the amount of silicon, reaction pH, time and temperature were investigated; the products were characterized by TEM, XRF and XRD. Which the best coating condition is formed, that is, the coating temperature is85℃-90℃,coating pH is9-10,coating time is3hours, coating dosage is4%-5%.(4) Surface modification of titanium dioxide by silicon and alumina.The surface of titanium dioxide was coated by silicon and alumina through chemical deposition using NaSiO3, Al2(SO4)3, NaOH and H2SO4as film coating. The influences on weatherability, oil absorption, acid soluble rate and hiding power of the mass ratio of SiO2and Al2O3, coating order, time and temperature were investigated. The products were characterized by TEM, XRF and XRD. Which the best coating condition is formed, that is, the coating order is adding silicon first and then aluminum, coating time is3hours, coating temperature is90℃, the silicon percent in coating agent is3%and alumina percent in coating agent is1%.(5) Surface modification of titanium dioxide by organic matter.The dispersion testing method is studied through settlement experiment in this work. The dispersion and stabilization of TiO2power in suspension under different film coating, different temperature, different time and the amount of film coating were investigated. The experimental results indicate that the best dispersion conditions are film coating is silane coupling agent (0.5%, weight ratio), at35℃～40℃, heating30minutes.Compared weatherability, acid soluble rate and dispersion of the four coating technology.Which the best coating condition is formed, that is, the silicon percent in coating agent is3%and alumina percent in coating agent is1%,the coating order is adding silicon first and then aluminum, coating temperature is90℃, coating time is3hours.The dispersion is improved greatly througth coating silane coupling agent in the organic medium.The novelties of the work are mainly focused on the following aspects:(1) The best coating process,through the first inorganic coating,organic coating.The titanium dioxide chromatism is about1,better than1.5of R902,acid soluble rate is about12%,better than13%of R902.(2) The survey of slurry absorbance was used in dispersion of titanium dioxide.This is a new survey method of dispersion.The result keeps pace with settlement experiment and Zeta electric potential experiment.