甲基丙烯酸甲酯改性硅树脂制备金属防腐涂层

Methyl Methacrylate Modified Silicone Coats for Metallic Corrosion Protection

以三甲氧基硅烷（trimethoxysilane,TMOS）与甲基丙烯酸甲酯（methylmethacrylate,MMA）为原料,氯铂酸为催化剂进行硅氢加成得到产物MMA-TMOS,再与甲基三甲氧基硅烷和苯基三甲氧基硅烷进行水解、缩合制备甲基丙烯酸甲酯改性有机硅树脂（MMA modifiedsiliconeresin,MMA-SR）;以甲基苯基二甲氧基硅烷进行水解、缩合制备硅油（siliconeoil,SO）.以石油醚作为溶剂,树脂与硅油按一定质量比,并加入一定量有机锡催化剂、双氨类偶联剂以及填料进行混合制成有机硅涂料,在马口铁表面形成保护涂层,采用DSC曲线、粘附性、邵尔A硬度、断裂弯曲半径、开路电压（OCV）和保护涂层的电化学阻抗谱（EIS）来评估涂层的耐热性,机械性能和耐腐蚀性.改性后的有机硅涂料各项性能明显提高,邵尔A硬度最高达60度,附着力1级,弯曲半径2.5mm;其热分解温度为338.6℃,略低于未改性涂料的341.5℃,基本保持了有机硅树脂的热稳定性;在3%NaCl溶液中浸泡4d,涂料开路电位相对于未改性涂料正移0.476V,电化学阻抗也提高了8.6×10~7Ω·cm^2,防腐蚀性能得到一定增强.

Silicone resins modified with methyl methacrylate （MMA-SR） were prepared from methyltrimethoxysilane （MTMOS）, phenyltrimethoxysilane （PTMOS）, and MMA-TMOS from the hydrosilylation of trimethoxysilane （TMOS） and methyl methacrylate （MMA）. Silicone oil （SO） from methylphenyldimethoxysiliane （MPDS） were also prepared. Silicone protecting coats, mainly from silicone resin and linear silicone prepolymers, with petroleum ether as solvent, dibutyltin dilaurate as curing catalyst, double ammonia coupling agent as curing accelerator and filler, formed on tinplate surface. Differential scanning calorimeter curve, adhesion, Shore A hardness, bending radius at break, open circuit voltage （OCV）, and electrochemical impedance spectroscopy （EIS） of protection coats were determined to evaluate the thermal resistance, mechanical property and corrosion resistance of coats. It was found that the modified silicone coats are greatly improved in mechanical property and corrosion resistance, for instance, coats from MMA modified silicone resins （20% of MMA to prepare silicone resins） and linear silicone prepolymers with 3 ： 1 weight ratio, in addition of 5% dibutyltin dilaurate, 2.5%（N-（2-aminoethyl）-3-aminopropyl） tris-（2-ethoxy） silane, gave a 60 Shore A hardness, a 1 level adhesion, and a 2.5 mm bending radius at break, comparing to that of non-modified coats, 90, 3, and 7.5 mm, respectively. The thermal resistance kept unchanged that the thermal decomposition temperature is close to that of pure silicone coats （a little lower at 338.6℃ than that of unmodified coats, 341.5℃）. Open circuit voltage （OCV）and electrochemical impedance spectroscopy （EIS） of coats, and its dependence on soaking time in 3.0% NaCI aqueous solution confirmed that, at the same coats increased by 0. 476 V with soaking time and its EIS are soaking time, OCV of above touched modified silicone 8.6 × 10Ω·cm^2 higher comparing to unmodified coats, which indicated a higher corrosion resistance.