Preparation And Properties Of Solvent-free Anti-corrosive Coatings With Heat-insulation For Petrochemical Pipeline

Composite layers consisting of anti-corrosive coating,heat insulation layer and protective layer are used to protect instruments and pipelines from water vapor and sunshine in domestic oil refining enterprises.Such protective composite layers are inconvenient for construction because of the thick heat insulation layer and thick protective layer with many joints.Moreover,once the protective layer loses sealing,rainwater and corrosive gas would readily penetrate into the heat insulation layer,reducing the heat insulation and damaging the anti-corrosive coating.It is urgent to develop environmental-friendly coatings with energy saving and emission reduction.In the present thesis,we prepared solvent-free coatings with anti-corrosion and heat insulation by using polymer resins,hollow glass beads(HGB),glass flake powder and some additives.The main contents and results are as follows.Solvent-free coatings based on glycidylamine epoxy resin fl-133,glycidyl ether epoxy resin E-44 and reactive solvent A were prepared and the properties were investigated.The coatings show excellent heat resistance,good anti-corrosion and high heat-insulation.At the weight ratio of fl-133 / E-44 / A of 2/4/4,the coating has flexibility less than 1 mm and adhesion more than 5.1 MPa.The coating does not show any change in appearance after heating at 150 ? for 24 hours.Besides,after immersing in 5% H2SO4 solution or 5% NaOH solution for 56 days or neutral salt atmosphere for 120 days,the coatings keeps undestroyed.The facts indicate their excellent anti-corrosive performances.We have studied the effects of the hollow glass beads and preparation conditions on coating properties.When the mixing speed is less than 500 rpm and HGB content is about 10%,the coating has the best insulation with thermal conductivity of 0.136 W/(m·K).Electrochemical impedance spectroscopy(EIS)is applied to determine the corrosion kinetics of the coatings.After the coating is immersed in 3.5% NaCl solution for 6 hours,the electrolyte solution gradually penetrate into the substrate of the coating and starts the electrochemical reactions,so that the coating goes bad in protection performance.When the immersion time is up to 120 hours,the impedance at 0.1 Hz was less than 106?,and the coating fails in protection.Simulated petrochemical field is set up to evaluate the heat insulation performance of thecoatings in applications.Our study demonstrates that the coatings exhibit high heat insulation and can meet the requirements for insulation in petrochemical industry.