| 1. The preparation method of epoxy resin, silica, silicone resin, silicone modified epoxy resins are reviewed. Epoxy resin, epoxy resin molecules at both ends, secondary alcohol side groups and ether linkages in the main chain, has excellent bonding properties, high mechanical strength after curing, chemical stability, low thermal expansion coefficient and good corrosion resistance, is widely used as adhesives, coatings etc. But it has big internal stress, poor fluidity, hardness after curing, relatively poor flexibility. In addition, there are drawbacks such as:poor heat resistance, fatigue resistance, cracking resistance and humidity resistance. Thus its application is restricted in some high-tech fields. Silicone resins have many excellent properties as a thermosetting polymer material, such as excellent heat resistance, weather resistance, water repellency, and electrical insulation, etc. To complement the shortcomings of the epoxy resin.This paper presents a method of organic silicone modified epoxy resin, synthesized silicone copolymer owing both organic and inorganic performances and modified the epoxy resin to improve its flexibility and heat resistance, weather resistance, corrosion resistance and other properties.2. Preparation of SiO2-silicone copolymersSiO2-organic silicone copolymers were prepared using two-step hydrolysis polymerization.1) TEOS was used as materials to hydrolyze into silica sol; both orthogonal test and parallel test were applied to determine the best process parameters of the preparation of silica sol:reaction temperature50-60℃, pH3,the molar ratio of water to TEOS3:1, the molar ratio of ethanol solvent to silicone monomer3:1.2) And then the activated SiO2-silicone copolymer prepared from several alkyl silane was added in a certain proportion, and the optimum conditions were determined by orthogonal test and parallel test:molar ratio of TEOS to organic silicon monomer1:5, R/Si value1.4, Ph/R value0.2, pH3.0, reaction temperature70-75℃. The SiO2-silicone copolymer can also be used as binders of heat resistant coatings, TGA showed that:the heat resistance of the silicone copolymer was significantly improved due to the introduction of SiO2. TGA showed that:the heat resistance of the silicone copolymer was significantly improved due to the introduction of SiO2.the heat resistance of the silicone copolymer400℃, weight loss rate of only6%,700℃high temperature residual rate of81%.3. The SiO2-silicone copolymer copolymerization of epoxy resin E-44chemicalEthoxy and hydroxyl groups of silicone copolymers were polycondensed with secondary hydroxyl groups of epoxy resin E-44to produce block polymers to improve the performance of the mixed system. The optimum process conditions were determined through researches on various factors affecting the synthesis reaction: mass ratio of SiO2-silicone copolymer to epoxy resin E-44is6:4, the amount of catalyst p-toluenesulfonic acid formed3%of the total amount of material, reaction temperature75-85℃, reaction time3-4h. IR, TGA, mechanical property testing showed that:the expected reaction occured, the SiO2-silicone copolymer has been successfully grafted to the epoxy resin chain. Modified epoxy resin has excellent heat resistance, flexibility and high adhesion and hardness.Modification of epoxy resin by thermal decomposition temperature and thermal weight loss of50%temperature ratio of epoxy resin were increased by100℃and140℃, Preparation of coating as SiO2-silicone copolymer and epoxy resin E-44mass ratio of6:4,the adhesion to reach level1, the hardness of2H, Flexibility for lmm, Heat-resistant coating temperature reaches300℃.4. The preparation of solvent-based zinc-rich coating using modified epoxy resin as base material. The coating structure and surface morphology were characterized using scanning electron microscopy, AC impedance and salt spray experiment and solution immersion method for the determination of the corrosion resistance of the coating. Muffle furnace for the determination of the heat resistance of the coating, UV aging experimental determination of the coating anti-aging properties. The results showed:compared with pure epoxy resin coatings, the heat resistance of zinc-rich coating using modified epoxy resin as binder was significantly improved, and it also possessed better corrosion resistance, weather resistance and water resistance. |
PDF Full Text Request