Preparation And Properties Of Waterborne High Temperature Resistant Silicone Coatings

In the process of modern industrial development,many equipment work in high temperature environment,such as boiler,chimney,heating pipe,automobile exhaust pipe,muffler and so on.Compared with normal temperature corrosion,high temperature corrosion is faster and more harmful;It is an effective solution to coat a layer of high temperature resistant and anti-corrosion coating on the surface of high-temperature equipment.In this paper,a green and environmental friendly waterborne high temperature resistant silicone coating is developed by using the excellent high temperature resistance of silicone resin.The paper mainly includes the following two parts:In the first part,through the screening of film-forming resin,filler and additives,a high temperature resistant waterborne silicone coating was developed.The effects of different film-forming resins,types and amounts of antirust pigments,types and amounts of glass powder with different melting points,yen base ratio and additives on the mechanical properties,water resistance,salt fog resistance and salt fog resistance of high temperature water-resistant silicone coatings were studied.The resin and coating were characterized and analyzed by Fourier infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),electrochemical impedance spectroscopy(EIS),thermogravimetric analysis(TG).The experimental results show that when dow-8016 resin is used as film-forming resin,9%aluminum tripolyphosphate,10 ～ 15% GT-45 low melting point glass powder are added,the color base ratio is 1.5:1 ～ 1:1,and the defoamer is dow-8590,the comprehensive properties of the coating are the best: adhesion is grade 1,pencil hardness is HB,flexibility is 0.5mm,impact strength is 50 kg · cm,water resistance for 24 h and salt spray resistance for 48 h.Due to the melting and bonding effect of low melting point glass powder,The coating can withstand salt spray for 240 h after holding at 600 ℃ for 3 hours.In the second part,in order to improve the anti-corrosion performance of silicone coating and reduce the cost,the silicone coating was physically modified.The effects of different acrylic lotion and its dosage and curing temperature on the properties of high temperature resistant waterborne silicone coatings were studied,and the high temperature resistance of the coatings was also investigated.The results show that when the silicone acrylic lotion is used to replace 25% of silicone resin in the coating,the water resistance of the coating increases to 72 h,and the salt spray resistance increases to 72 h.Meanwhile,the low density melting glass powder is used to melt and bind the pigments and fillers during the heating process,so that the coating density is increased.The salt spray of the coating can reach 240 h after heating,and the coating can basically meet the requirements.At different curing temperatures,the adhesion of the varnish coating is grade 0.When the curing temperature is 200 ℃,the maximum crosslinking rate of the coating is 97.2%;At 300 ～400 ℃,the coating surface of silicone and silicone acrylic silicone coatings appears pulverization and yellowing,and the cohesion strength of the coating decreases.At 500 ～600 ℃,the coating color is white,which is not different from that of the coating before heating,and the adhesion is grade 1.