水性硅酸锂改性防锈剂的制备研究

发布时间：2019-04-29 19:34

【摘要】：金属制品在人们日常生活以及经济建设中占据了重要的地位,但金属制品在储存和使用过程中,非常容易受到环境中许许多多因素的影响,从而导致腐蚀,进而会使金属产品的颜色、光泽、外形还有性能受到损伤。传统的油性防锈剂涂覆后外观差,需后续清除。传统水性防锈剂防锈性能不够理想,且大多含有亚硝酸盐、铬酸盐等有毒有害的物质,会污染生态环境,因此,研制出一种性能优良、环保的金属防锈剂,意义重大。硅酸锂是一种水性防锈剂,具有良好的成膜性和成膜后的稳定性,无毒无害。硅烷偶联剂具有无机反应性基团和有机反应性基团,可以和有机与无机材料发生化学键合(偶联)、交联反应,能有效地改善防锈膜强度,提高涂层与基体之间的结合力。有机酸是一种有效的螯合剂,能在一定程度上起到增进膜附着力的作用,且在较大pH值的范围内保持较强稳定性。少量的Zn(H2PO4)2·2H2O可水解生成碱式磷酸盐,该盐类难溶于水,能堵塞防腐层中表面的针孔。与此同时,Zn2+可同金属基体表面的羟基反应,生成难溶的Zn(OH)2,也可堵塞表面针孔。六次甲基四胺由于静电引力的作用,不断趋近于金属表面,发生物理吸附作用,而后N原子上孤对电子和金属中的空d轨道配对成键即配位键,从而产生很强的化学吸附,可提升防锈膜物理化学性能。本文制备低浓度硅酸锂溶液为基料、加入偶联剂KH550、六次甲基四胺、磷酸二氢锌、有机酸等助剂按一定比例混合反应,复配出一种具有协同作用,物理性能优良、高附着力、防锈性能优良的水性防锈剂。文章采用单因素实验和正交实验,考察硅酸锂溶液的添加量和模数,磷酸盐、有机酸、胺类化合物添加量,硅烷偶联剂体系添加量及组成对防锈剂防锈性能的影响。实验确定最优配方:在水性防锈剂200ml中:硅酸锂溶液84g,M硅酸=4.0;六次甲基四胺0.03g,磷酸二氢锌0.025g,硅烷偶联剂KH550体系(VKH550:V水:V乙醇1:8:1)0.25ml,有机酸0.02ml。以此配方形成的防锈膜,固化速度快,成膜性能好,附着力高,防锈性能优良。按上述配方制备出防锈剂,试件在其中浸泡5min后取出,于25℃条件下干燥 120min 后,用含有 41g/L CuSO4·5H2O、35g/L NaCI、13ml/LHCI混合制备的CuSO4点滴,233 s后才出现腐蚀痕迹,用3%盐水浸泡62min才出现腐蚀痕迹,用中性盐雾实验361h才出现腐蚀痕迹,防锈性能优良。通过对试件和防锈剂的膜干燥时间(表干和实干)、铅笔硬度、附着力、柔韧性等性能进行检测,通过环境扫描电镜SEM分析、红外光谱分析(反射吸收红外光谱RA-IR)、热重分析、X射线能谱法(EDS)分析表征,该防锈剂固化的膜具有很好的对金属的附着力、润湿性、具有优良的硬度、柔韧性,快干性,物理性能优良。
[Abstract]:Metal products play an important role in people's daily life and economic construction, but in the process of storage and use, metal products are very vulnerable to the influence of many factors in the environment, which leads to corrosion. In turn, metal products will be damaged in color, luster, shape and performance. Traditional oil anti-rust agent after coating poor appearance, need to be removed. The antirust performance of traditional water-based antirust agent is not ideal enough, and most of them contain toxic and harmful substances such as nitrite, chromate and so on, which will pollute the ecological environment. Therefore, it is of great significance to develop a kind of metal antirust agent with excellent performance and environmental protection. Lithium silicate is a kind of water-borne antirust agent, it has good film-forming property and stability after film-forming, it is non-toxic and harmless. Silane coupling agent has inorganic reactive group and organic reactive group, can be chemically bonded (coupled) with organic and inorganic materials, cross-linking reaction, can effectively improve the strength of antirust film, improve the bonding force between coating and matrix. Organic acid is an effective chelating agent, which can enhance the adhesion of membrane to a certain extent, and maintain a strong stability in the range of larger pH value. A small amount of Zn (H2PO4) 2 2H2O can be hydrolyzed to form basic phosphate, which is insoluble in water and can clog the pinholes on the surface of the coating. At the same time, Zn2 reacts with hydroxyl groups on the surface of metal matrix to form insoluble Zn (OH) 2, which can also block the surface pinholes. Due to the action of electrostatic gravity, hexamethylenetetramine (hexamethylenetetramine) is getting closer to the surface of metal and physical adsorption occurs. Then, the pair of electrons on the N atom and the empty d orbitals in the metal are paired together, that is, the coordination bond, resulting in a strong chemisorption. It can improve the physical and chemical properties of antirust film. In this paper, the low concentration lithium silicate solution was prepared as the base material, the coupling agent KH550, hexamethylenetetramine, zinc dihydrogen phosphate, organic acid and other auxiliaries were mixed in a certain proportion to give a kind of synergistic effect, good physical properties and high adhesion. A water-borne antirust agent with excellent antirust properties. In this paper, the effects of addition and modulus of lithium silicate solution, phosphate, organic acid, amine compound, silane coupling agent system and composition on antirust performance of antirust agent were investigated by single factor experiment and orthogonal experiment. The optimum formula was determined as follows: in water-borne antirust agent 200ml: lithium silicate solution 84g, M silicic acid = 4.0; Hexamethylenetetramine 0.03g, zinc dihydrogen phosphate 0.025g, silane coupling agent KH550 system (VKH550:V water: v-ethanol 1:8:1) 0.25 ml, organic acid 0.02 ml. The anti-rust film formed by this formula has the advantages of high curing speed, good film-forming performance, high adhesion and good rust-proof property. After soaking in 5min and drying 120min at 25 鈩，

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