The Preparation And Surface Modification Of Silicon Oxide Microparticle

The silicon oxide microparticles is widely used in various fields because of its environmental characteristics of non-toxic and non-polluting.In the preparationproces of micron particals which has very high surface activity,it is very easy to Particals to generate agglomeration.In order to overcome agglomeration and produce micron sized silic which has narrow particle size distribution,Secondary treating,mainly is jet milling,it is used in modern industry.Jet milling not only results in high power consumption,loud noise,flying dust and poor production environment,but also under mines the morphology of the particles,reduce the original performance.Further,thesince the surface of the particles having a hydrophobic-hydrophilic propertiy,micron sized particles of SiO₂ are very difficult to uniformly disperse when they are added to various organic compounds.For this reason,performance of composite material property difficult to play.To avoid secondary treating,the artical prepared fine silicapowder,which has narrow particle size distribution and good dispersion,through thechemical precipitation method.At the same time,surface-modified of SiO₂ is achived.The test results in this paper can be used in actual production and provided guides in actual production.Water glass and H₂SO₄ as raw materials and ordinary drop acid as experiment method,this artical discussed optimum conditions for preparing micron sized silica.Adding 1.5wt.%dodecyl benzyl trimethyl ammonium chloride,SiO₂ particles whose D₅₀=6.46μm and size distribution is 4¹1μm,are obtained.But,when add 1.8wt.%ethanol to these hard agglomerated particles,aggregates of nanoscale beads whose average particle diameter is 6.8μm and size distribution is 5⁹μm are obtained.The SiO₂ particles are characterized by SEM and laser particle size analysis.At The same time,dispersion mechanism of ethanol and dodecyl benzyl trimethyl Amonium chloride is explored.Using stepwise heating method,spherical particles whose D₅₀=5μm and size distribution is 4⁶μm are obtained by regulating reaction Conditions and adding dispersants.The reaction mechanism of stage stepwise heating method is also explored.NH₄Cl and water glass as raw materials,The article determines gob order,the best NH₄Cl concentration,reaction temperature,feed rate and drop titration point pH and other process conditions.When adding amount of dodecyl benzyl trimethyl ammonium chloride is 1.6wt%,SiO₂ products of aggregates consisting of nanoscale balls obtained.By regulating aging conditions and microwave heating,very good dispersion on SiO₂ fluffy powder whose D₅₀=5μm and size distribution is 4⁶μm are obtained.This article also discussed corresponding reaction mechanism.In this paper,a two-step method is used to modifiy SiO₂.And optimum process conditions are determined by experiments.Based on the degree of activation,hydroph obic angle and heat resistance,modifiers are screened.The results showed that silane coupling agent KH570 performs better for modifing SiO₂ products compared with boric acid ester coupling agent,When KH570 is chosen as a modifier,the active ratio of product can reached to 99.47%and water contact angle is 119.45°.When the heat treatment temperature is up to 220℃,the active ratio is still above97%.Compared with the mechanical properties of unmodified SiO₂/PVC composite materials,modified SiO₂/PVC composite elongation at break is 1.26 times of unmodified SiO₂/PVC composite,and the impact strength increased by 23%.