Preparation And Study Of Modified Silica Sol With Low Surface Energy

Hydrophobic surface plays an important role in self-cleaning,anti-corrosion,anti-icing and other fields.There are two main methods:one is to coat the surface of materials with water-resistant coating,the other is to reduce the surface energy of materials.There is hydrophobic methyl in MTMS,and Si O₂has excellent performance to construct rough structure.By modifying Si O₂with MTMS,hydrophobic coating can be prepared by introducing low surface energy materials.In this paper,three series of modified silica sol with low surface energy were prepared by sol-gel method using silica sol and silane coupling agent.The preparation of water-based two-component modified silica sol mainly uses MTMS and silica sol as raw materials,nitric acid and acetic acid as p H regulators.Through the hydrolysis polycondensation reaction at room temperature,the optimum process was determined as follows:p H value was 3.5,m organosilane:m silicasol（mass fraction of Si O₂was 30%）=9:10,the obtained modified silicasol coating was kept at 180-300℃for 1 h,contact angle is more than 90°,hydrophobic,hardness is more than 6 H,temperature resistance up to about 500℃.The best preparation process of one component low surface energy modified silica sol is as follows:MTMS and silica sol are used as raw materials,m organosilane:m silica sol（mass fraction of Si O₂is 30%）=9:10,nitric acid is used as p H regulator,p H is 3.0,solvent is n-butanol and isopropanol respectively,solid content is 30%,after curing at room temperature and heating and holding for 1 h,the contact angle>90°,temperature resistance can reach500℃,and adhesion≤level 1.Methyl phenyl modified silica sol was prepared with methyl trimethoxy silica,diphenyldimethoxysilane and silica sol as raw materials.The optimum technological conditions were:p H:3.5,acetic acid as p H regulator,diethylene glycol butyl ether as solvent,R/Si value of 1.35,m organosilane:m silica sol（30%Si O₂mass fraction）=13:10.The contact angle of the one-component methyl-phenyl modified silica sol coating can not be greater than 90°,and the hardness≥6 H,and the heat-resistant temperature was about 450℃.In this paper,the modified silica sol coating prepared by the best process is studied in detail.The results show that the coating not only has good hydrophobic function,but also has excellent performance in high temperature resistance and hardness.