| High performance high chlorinated polyethylene(HPE)is a kind of thermoplastic hard and brittle resin,a large number of polar groups exist in the molecular chain segments,intermolecular forces is larger,paint film flexibility is poor,and unable to meet the anticorrosion demand of industrial pipe fittings and so on,in order to meet the requirements of better use,HPE coating needs to be modified.In this thesis,a single-component quick-drying coating with HPE flexibility modified by the thermoplastic acrylic resin is designed,which can greatly meet the needs of fast-paced production and high anti-corrosion of cast pipe fittings products.The modification conditions of pigments and fillers and the effect of modification on coating were also studied in detail in this thesis.Mechanical performance test,electrochemical impedance spectroscopy,contact angle measurement,infrared spectrum,scanning electron microscope,single factor and orthogonal test and other means were used to characterize the performance of the coating system.The study found that the film flexibility of the unmodified HPE coating is greater than 3mm,with poor flexibility.The addition of pigments and fillers can improve the film flexibility and impact resistance to a certain extent,but the effect is not very obvious.Therefore,to significantly improve the film flexibility,it must begin from the film-forming material to improve the film-forming material brittleness.By adding acrylic resin YZ-T105 blending modification,YZ-T105 has excellent anti-corrosion performance and improves the paint film flexibility at the same time.The experimental results show that the coating film flexibility is excellent after blending modification,both blending modification is feasible.Research on modified coatings shows that the acrylic resin YZ-T105 modified HPE was used as the main film-forming material,when 60%acrylic resin YZ-T105 solution and HPE quality control proportion is 2:3,mixed solvent ratio-control is 4:1,and the addition appropriate amount of defoaming agent and flatting agent,the varnish film have excellent mechanical properties and corrosion resistance,as well as excellent electrochemical impedance properties,the coating resistance Rp is up to 1.8×1010Ωcm2.Infrared analysis results also show that the filler surface modification of yan,stronger methyl or methylene,Si-O,C-Si group absorption peak.The contact angle test showed that the modified contact angle could reach 110-120 degrees after the pigments and fillers were modified by dow corning silane coupling agent Z-6173.The results of infrared analysis also showed that the strong absorption peaks of methyl or methylene,Si-O and C-Si perssad appeared on the surface of the modified pigments and fillers.At the same time,through single factor and orthogonal test to determine the best coating formulation,when the dosage of 60%acrylic resin YZ-T105 solution is 8g,HPE resin is 12g,the talcum powder dosage is 10g,mica powder dosage is 3g,titanium pigment and barium sulfate dosage are 4g and 3g,respectively,and under the conditions with moderate additive such as defoaming agent and flatting agent,the paint coating has excellent anti-corrosion performance.At room temperature,the anti-corrosion coating was immersed in a certain concentration of acid,alkali and salt corrosive medium for more than 7days respectively,and the coating had no change.The coating was immersed in sodium chloride solution with a mass fraction of 3.5%,the electrochemical impedance performance of the coating was regularly tested,and the resistance of the coating was basically after 60 days of immersion,and the coating resistance up to 1.6×1010Ω·cm2 after fitting calculation.After 500h salt spray test,the film is still in good condition,and has excellent adhesive force to the substrate.In conclusion,the modified coatings prepared in this thesis have excellent mechanical properties and corrosion resistance properties,etc.,which fully meet the standard application requirements of the cast pipe anticorrosive coating system. |
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