【作者】 张赢超；

【导师】 叶红齐；

【作者基本信息】 中南大学 ， 化学工艺， 2012， 博士

【摘要】 为了使片状铝粉颜料满足水性及粉末涂料的环保要求并增加其颜色多样性,以普通片状铝粉颜料为研究对象,采用液相法研制了铝/二氧化硅(Al/SiO2)、铝/二氧化硅/氧化铁(Al/SiO2/Fe2O3)、铝/二氧化硅/普鲁士蓝(Al/SiO2/PB)三种复合粒子。为了获得包覆物在片状铝粉表面优良的包覆效果,考察了包覆物与底材表面电荷的匹配及表面活性剂的作用,优化了制备过程各主要影响因素,对所制备的复合粒子的分散性、耐腐蚀性及颜色特征等性能进行了表征,最后考察了三种复合粒子在水性及粉末涂料中的应用。1、溶胶凝胶法制备Al/SiO2复合粒子及其表征。以正硅酸乙酯(TEOS)水解缩合及A1与Si02间静电吸附理论为依据,实验考察了水(nw)、乙二胺(nE)、正硅酸乙酯(nTEOS)及铝(nAl)之间摩尔比的影响,结果表明：nW:nTEOS、nE:nTEOS和nTEOS:nAl的增大有利于提高包覆效率(CE)和包覆率(PC),可增强Al/SiO2复合粒子的耐腐蚀性能,但摩尔比太高会导致片状铝粉间的团聚,影响复合粒子的分散性能；最佳条件为：nw:nTEOS=11.6,nE:nTEOS=5.54×10-2,nTEOS:nAl=6.06×10-2,此时CE值可达到99.6%。包覆前后粒子的中位径分别为16.05和16.20μm,表明复合粒子之间基本无团聚现象；SEM、EDS及FTIR分析表明Al/SiO2复合粒子表面存在一层二氧化硅包覆膜；AFM分析表明二氧化硅包覆层表面均匀平整,平均粗糙度(Ra)仅为3.9nm；BET结果表明表面包覆层结构比较致密,其平均孔径为19.4nm,孔隙率仅为7.52%。2、表面活性剂在Al/SiO2复合粒子表面的吸附。依据静电引力及疏水力作用原理,考察了三种表面活性剂在Al/SiO2表面的吸附特性,发现十六烷基三甲基溴化铵(CTAB)在Al/SiO2粒子表面的吸附可能是双层吸附,第一层通过静电引力产生吸附,第二层的吸附作用力则是长碳链间的疏水力。Al/SiO2表面对十二烷基硫酸钠(SDS)吸附量很少。壬基酚聚氧乙烯醚磷酸酯(PPOP)在不同pH条件下表现出非离子或阴离子表面活性剂的特性,在Al/SiO2粒子表面可能产生多层吸附。通过表面活性剂的吸附可在一定范围内调控Al/SiO2复合粒子表面电性等性能。3、液相沉淀法制备Al/SiO2/Fe2O3复合粒子及其表征。在Al/SiO2表面进行Fe2O3的包覆过程中,考察了表面活性剂、pH等参数的影响。结果表明：SDS和CTAB对CE有抑制作用,而PPOP能显著提高CE值,并有利于氧化铁在Al/SiO2表面形成均匀的纳米颗粒膜,最佳浓度条件下样品的CE值可达到95.5%。随着反应过程pH值的增大,形成包覆层的氧化铁颗粒粒径呈增大的趋势,会降低金属鳞片动态式指数(FI)。XRD结果表明Al/SiO2/Fe(OH)3表面的颗粒膜是无定型的,450℃锻烧后可转变为α-Fe2O3。锻烧后制得的Al/SiO2/Fe2O3复合粒子,由Al/SiO2的银灰色转变为金黄色,且具有明显的“随角异色”效应。4、液相沉淀法制备Al/SiO2/PB复合粒子及其表征。实验考察了PB包覆过程的影响因素,发现采用阳离子表面活性剂CTAB对PC及CE具有明显的提升作用,其中CE可达到99.5%,pH值及温度对CE的影响很小。SEM和XRD结果表明包覆层为PB纳米粒子组成的颗粒膜,排列均匀致密,为立方相普鲁士蓝。经PB包覆后,复合粒子表面的平均粗糙度为16.9nm。制备得到的Al/SiO2/PB复合粒子呈蓝色并具有极强的金属光泽,色差仪分析结果表明复合粒子至少在三个角度具有不同的颜色。5、片状铝粉复合粒子在涂料中的应用。选取某国外产品为参比对象,对制得的三种复合粒子在普通商用水性涂料和粉末涂料中的应用性能进行了系统地对比分析,结果表明：四种复合粒子的储存稳定性均优良,附着力等级达到国家标准1级以上,含Al/SiO2和Al/SiO2/Fe2O3的色板的耐酸碱性能明显好于国外样品。对复合粒子耐腐蚀性能的研究表明,采用pH10的氢氧化钠溶液为腐蚀液可对片状铝粉颜料在水性涂料中的稳定性进行快速定量检测,40℃10天的析氢量小于1ml/g可满足实际水性涂料90天的储存要求,大大缩短了含铝粉颜料的水性涂料稳定性的检测时间。更多还原

【Abstract】 Silica coated flaky aluminium powders (Al/SiO2), ferric oxide and silica coated flaky aluminium powders (Al/SiO2/Fe2O3) and Prussian blue and silica coated flaky aluminium powders (Al/SiO2/PB) were developed using common flaky aluminium pigments as subject by liquid method to meet the needs of waterborne coatings and powder coatings and to improve the color diversity. For good coating layer on alminium powder, the charge proportion between coating material and base, role of surfactants and main influencing factors of preparation process were investigated. Dispersibility, corrosive resistance and color feature of composite particles were characterized, and also, the application of three composite particles in waterborne coatings and powder coatings were studied.1. The preparation of Al/SiO2composite particles by sol-gel method and their characterization. Based on the theory of hydrolytic condensation of tetraethyl orthosilicate (TEOS) and electrostatic adsorption between Al particle and silica, the concentrations of water (nw:nTEOs), ethylenediamine (nE:nTEOs) and TEOS (nTEOs:nAl) were investigated deeply. Results of the tests indicated that the improvement of nw:nTEOS, nE:nTEOS and nTEOS:nAl help the coating efficiency (CE) and percentage of coating (PC) values and improve the corrosive resistance, however, exceptionally high concentration will lead to aggregation and therefore reduce the dispersibility. The optimum conditions are nw:nTEOS=11.6, nE:nTEOS=5.54×10-2, nTEOS:nAl=6.06×10-2and CE value is99.6%. Grain size of Al and Al/SiO2indicated that the composite particle have excellent dispersibility. Results of SEM、EDS and FTIR analyses proved that there is a layer of silica coating on the surface of flaky aluminium particle. The average roughness (Ra) is only3.9nm through AFM analysis. Average pore size and porosity are19.4nm and7.52%, indicating that the coating layer is dense.2. Adsorption of surfactants on Al/SiO2surface. According to the theory of electric attraction and hydrophobic force, the adsorbing of three surfactants on Al/SiO2surface was investigated. The results showed that the adsorption of cetyltri methyl ammonium bromide (CTAB) on Al/SiO2surface may be two layers, which one is obtained by electric attraction and the other is by hydrophobic force among the long-chain carbon. Quantity of adsorbing for sodium dodecyl sulfate (SDS) on Al/SiO2surface is poor. The structure of phosphate polyoxyethylene octyl phenol (PPOP) is affected by pH, therefore, it exhibits the characteristic of non-ionic surfactant or anionic surfactant. Adsorption of PPOP on Al/SiO2surface may be multilayer structure. The surface charge of Al/SiO2could be easily changed through the adsorption of surfactants.3. The preparation of Al/SiO2/Fe2O3composite particles by liquid precipitation and their characterization. The influence of parameters like surfactants, pH and so on were investigated during the coating of Fe2O3. The results showed that SDS and CTAB are harmful to CE, however, PPOP is very beneficial to the CE value which is95.5%under the best PPOP concentration. The particle size of Fe2O3increases with the increase of pH leading to the decrease of flop index (FI). Results of XRD indicated that the nano particle structure is amorphous and it will be transformed into α-Fe2O3through calcination at450℃. The gained Al/SiO2/Fe2O3is golden color and has excellent sparkle effect.4. The preparation of Al/SiO2/PB composite particles by liquid precipitation and their characterization. It can be seen that CTAB benefits PC and CE, however, pH and temperature influence the CE value little. The highest CE value is99.5%. SEM and XRD results showed that the layer is composed of nano cubic phase PB particles. Ra is16.9nm. Al/SiO2/PB composite particles are metallic blue and at least have three colors under different angles.5. Application of flaky aluminium composite particles in coatings. Compared with the product abroad, the performance of the three composite particles in waterborne coatings and powder coatings were tested systematically. The results showed that storage stability of the four is good, adhesion rate is above1according to national standard and anticorrosive of paint film with Al/SiO2or Al/SiO2/Fe2O3is better than product abroad. The anticorrosive of composite particles indicated that the stability of aluminium pigments in waterborne coating could be tested rapidly and quantitatively through sodium hydroxide of pH10. The gas volume less than1ml/g in10days at40℃could meet the stability about90days for the actual waterborne coatings, reducing the stability testing time for waterborne coating which contains aluminium pigments.更多还原