Preparation Of New Types Of Microcapsules And Its Anticorrosive And Wear-resistant Coatings

Coatings are the most effective and simple way to prevent metal corrosion,but the coatings are prone to cracks and wear during actual application.By introducing microcapsules with self-repairing function and strong mechanical properties into the coatings,the coatings can be given anti-corrosion and wear resistance,which can effectively solve the actual problems faced by the coatings.In this article,in-situ polymerization and Pickering emulsion methods were used to prepare urea-formaldehyde resin(PUF)/silica(Si O₂)hybrid microcapsules coated with linseed oil and corresponding microcapsule coatings;the interfacial polymerization method was used to prepare polyurea(PU)/Fly ash-linseed oil(FA)microcapsules and corresponding microcapsule coatings.The main content of the article can be summarized as follows:(1)Optimal preparation conditions for PUF/Si O₂ hybrid microcapsules:Select 24#modified Si O₂ as emulsifier with content of 1 wt%;mechanical stirring speed is 500 rpm,and inorganic salt ammonium chloride(0.5 wt%)is added.The particle size of the hybrid microcapsules is about 30?m,and the wall thickness is 3?m.The thermal decomposition temperature of the microcapsule is 240-550?,and there is 6.7 wt%Si O₂ residue after thermal decomposition;the content of the core material linseed oil is 80.7 wt%.When the microcapsule content of the epoxy resin coatings is 10 wt%,the friction coefficient and the wear amount are at the minimum,which are 0.045 and 0.0182 g/4h,respectively,which are much higher than the pure epoxy resin coatings.After 1.2 h of friction,the pure epoxy coatings has been completely worn,and when the friction time is extended to 4 h,the wear change of the microcapsule coatings has a significant increase.This is mainly due to the lubricating properties of linseed oil and the wear resistance of Si O₂.When the scratched area of 10 wt%microcapsule coatings is immersed in 3.5 wt%Na Cl aqueous solution for 1 day,the impedance modulus is8.0×10⁸?/cm²,which is much higher than the scratched area of epoxy coatings 4.2×10⁴?/cm²;After 30 days of immersion,the impedance modulus of the 10 wt%microcapsule coatings becomes 1.5×10⁷?/cm²,which is only an order of magnitude decrease,indicating that the 10wt%microcapsule coatings has excellent corrosion resistance.(2)The prepared PU/FA microcapsules have a particle size of about 35?m,the thermal decomposition temperature of PU/FA microcapsules is 210-550?,the content of fly ash in the microcapsules is 56.1 wt%,and the content of linseed oil is 33.5 wt%.The wear amount of the pure epoxy coatings without PU/FA microcapsules is 388.1 mg/8h,and the friction coefficient is 0.15.The wear of the coatings with 10 wt%PU/FA microcapsules was reduced to2.4 mg/8h,which is 161.7 times lower than that of the pure epoxy coatings,and the friction coefficient was reduced to 0.05.The fly ash in the PU/FA microcapsules plays a very good supporting role in the entire coating structure,improving the overall mechanical properties of the epoxy coatings,coupled with the lubricating effect of linseed oil,the PU/FA microcapsule coatings plays a very good abrasion resistance effect in the abrasion test.The impedance modulus at 0.01 Hz in the 10 wt%PU/FA microcapsule coatings is 10⁹?/cm²,which is only one order of magnitude lower than that of the unscratched area and three orders of magnitude higher than that of the uncured area of 10⁶?/cm².Because the repairing agent linseed oil released from the PU/FA microcapsules fills the scratched area due to capillary action to repair the scratched area.It is showed that the PU/FA microcapsule coatings still has good anticorrosion properties after introducing fly ash into the microcapsules.