【作者】 高爱环；

【导师】 程江；

【作者基本信息】 华南理工大学 ， 化学工程， 2010， 博士

【摘要】 鳞片状铝颜料具有独特的金属光泽和“随角异色”效应,是广泛应用于涂料、油墨等行业的重要金属颜料。为了提高铝颜料的耐腐蚀性和与树脂相容性,本文采用丙烯酸树脂单层包覆、丙烯酸树脂/二氧化硅相双层包覆以及丙烯酸树脂/二氧化硅复合层包覆对铝颜料进行表面改性。本文首先以甲基丙烯酸甲酯(MMA)、丙烯酸乙酯(EA)、丙烯酸丁酯(BA)、丙烯酸(AA)和甲基丙烯酸-2-羟基乙酯(2-HEMA)等为单体,采用溶液聚合法制备了透明的羟基丙烯酸树脂,并通过吸附使羟基丙烯酸树脂在铝颜料表面形成一层包覆层,制备了羟基丙烯酸树脂包覆型铝颜料。考察了加料方式、树脂用量、反应温度和包覆时间等因素对铝颜料的表面形貌、耐腐蚀性和在涂层中粘附性能的影响,结果表明,当铝颜料用量为1.5 g,树脂用量2.0 g以上,温度达50℃,包覆时间2 h以上,羟基丙烯酸树脂在铝颜料表面可形成较好的包覆层。该包覆层对铝颜料的金属光泽影响较小,可提高铝颜料的耐酸腐蚀性能,并明显增强铝颜料在涂层中的粘附性能。而高温高湿测试表明,氢键作用力弱,羟基丙烯酸树脂在铝颜料表面形成的包覆层不稳定,需要采取其他措施增强铝颜料的耐腐蚀性及其与树脂的相容性。为了增强包覆层与铝颜料之间的结合力,将sol-gel法与原位聚合法相结合,制备了SiO2和聚丙烯酸酯(PA)双层包覆型铝颜料PA/SiO2/Al。首先以正硅酸乙酯(TEOS)和乙烯基三乙氧基硅烷(VTES)作为共同前驱物,通过溶胶/凝胶反应在铝颜料表面形成一层乙烯基活化的二氧化硅包覆层,在铝颜料表面引入可聚合的碳碳双键;然后在二甲苯和乙酸丁酯的混合溶液体系中,以MMA和丙烯酸甲酯(MA)为单体,在乙烯基活化二氧化硅包覆铝颜料(V-SiO2/Al)表面进行自由基聚合反应,于铝颜料表面包覆一层PA。通过考察单体用量、反应时间及反应温度等因素对铝颜料的形貌、金属光泽、耐腐蚀性能以及与树脂相容性的影响,得出结论如下:铝颜料用量1.5 g,单体用量0.7 g、聚合温度85℃、聚合时间4～6 h时,制备的PA/SiO2/Al在涂层中分散性能良好,涂膜外观平整光滑,明度值较原料铝颜料下降6.67,表明双层包覆对铝颜料的金属光泽影响较小;涂层经pH=1酸液浸泡不变色,表明铝颜料的耐腐蚀性得以增强;铝颜料脱落量为0,且高温高湿处理后无变化,说明包覆层促进了铝颜料与树脂相容性。红外(FTIR)和X-射线光电子能谱(XPS)分析证明SiO2和PA先后成功包覆于铝颜料表面。为了简化包覆过程和最大限度降低包覆层对铝颜料金属光泽的影响,进一步开发了新型的有机-无机杂化包覆型铝颜料。首先采用溶液聚合法,以VTES、MMA和BA为聚合单体,在乙酸丁酯与二甲苯混合溶剂中合成了含硅氧烷的丙烯酸树脂PMBV。探讨出较为适宜的聚合条件为:nBA:nMMA:nVTES=2:2:1,BPO用量为单体总量3%,温度110℃。在该条件下,聚合反应转化率达92.5%,分子量3700,分子量分布2.056,产物无色透明。FTIR、氢核磁共振(1H NMR)、碳核磁共振(13C NMR)以及量热法(DSC)分析结果表明VTES、MMA和BA参与了共聚而非自聚反应。比色法测定树脂中硅元素含量为3.89%。随后研究了PMBV与TEOS的水解-缩聚行为。采用原子力显微镜(AFM)、FTIR、热重(TG)和硅核磁共振(29Si NMR)等分析方法分析了PMBV与TEOS水解-缩聚产物,结果表明,PMBV与TEOS在同一乙醇体系中水解、自缩聚与共缩聚同时发生,可形成均一透明的有机-无机杂化材料。变角XPS分析得出,铝表面Si、O和C元素含量随涂层厚度的变化而发生变化,表明在PMBV和TEOS的水解-缩合过程中,硅氧烷基团和硅醇与铝表面的羟基发生缩合反应。在上述PMBV和TEOS水解-缩合研究的基础上,采用PMBV与TEOS为共同前驱体,乙醇/水为分散体系,氨水为催化剂,通过sol-gel法在铝颜料表面包覆有机-无机杂化薄层,制备了PMBV-SiO2包覆型铝颜料PMBV-SiO2/Al。考察了PMBV与TEOS的配比及用量、氨水和去离子水用量对包覆效果的影响,并优化了包覆条件。当铝颜料的量为1.5 g,乙醇用量50 mL,氨水用量3 mL,去离子水用量3 mL,PMBV与TEOS之比为1:0.45~1(以硅计),PMBV和TEOS总用量13.1mmo(l以硅计), PMBV与TEOS可以在铝颜料表面形成比较均匀致密的包覆层。PMBV-SiO2/Al的明度值仅下降了0.24,有机-无机杂化包覆层良好的保持了铝颜料的金属光泽。FTIR、TG和XPS分析验证了PMBV和TEOS在溶胶-凝胶过程中发生水解和缩聚后在铝颜料表面形成了键合,并最终在铝颜料表面形成了一层致密的包覆层。提高共同前驱体中TEOS的含量有助于增强PMBV-SiO2/Al的耐腐蚀性能,表明PMBV-SiO2/Al的耐腐蚀性很大程度上取决于SiO2,而对比多种铝颜料的耐酸性也验证了这一结论。撕拉实验结果表明,PMBV-SiO2/Al在涂层中的粘附性能得到了很大的提高,说明PMBV和TEOS水解缩聚包覆铝颜料与树脂的相容性得到了提高,但与双层包覆型铝颜料PA/SiO2/Al相比,存在着微小的差距。更多还原

【Abstract】 Flaky aluminum pigments are widely used in paint and printing ink industry due to their uniquely metallic effect and“flop-effect”. In order to enhance the anti-corrosion propert and improve the compatibility with resin, the surface of aluminum pigments was modified by acrylate resin single layer, acrylate and silica double layers and acrylate composited with silica layer, respectively.Hydroxyl acrylic resin encapsulated aluminum pigments were prepared by adsorption of the resin on the surface of Al particles via hydrogen-bond, which has been pre-prepared by free radical polymerization of methal methacrylate (MMA), ethyl acrylate (EA), n-butyl acrylate (BA), acrylic acid (AA)and methacrylate -2 - hydroxy ethyl (2-HEMA). Effects of absorption conditions on the property of aluminum pigments were investigated. The results show that when the mass of aluminum pigments is 1.5 g and mass of resin more than 2.0 g, the hydroxyl acrylic resin film can be well-formed on the surface of aluminum pigments after at least 2h adsorption under the temperature of 50℃. The film can improve the anti-corrosion property of aluminum pigments and their compatibility with resin without reducing their metallic appearance. However, the hydrogen-bond between hydroxyl acrylic resin and aluminum pigments is very weak and easily to be destroyed.In order to enhance the binding force between encapsulated layer and aluminum pigments, polyacrylate (PA) and SiO2 double-layer encapsulated aluminum pigments (PA/SiO2/Al) were prepared via sol-gel method and in-situ polymerization. Firstly, aluminum pigments were encapsulated with a layer containing vinyl group activated silica using VTES and TEOS as precursors through sol-gel method. The second layer was then formed on the surface of aluminum pigments by free radical copolymerization of MMA, MA and C=C group of VTES in the presence of benzoyl peroxide (BPO). Effects of in-situ polymerization conditions on the morphology, the metallic appearance, the anti-corrosion property and the compatibility of aluminum pigments were also investigated. It was found that when the mass of aluminum pigments is 1.5 g, the mass of monomers is 0.7 g, the temperature is 85℃and the reaction time is 4~6 hrs, the as-prepared PA/SiO2/Al shows good dispersion in coating. The weight loss of PA/SiO2/Al from coating is almost 0 after peeling-off test under high temperature and humidity. The compatibility of PA/SiO2/Al with resin was improved resulting in stronger binding between layers and aluminum pigments. The L-value of coating containing PA/SiO2/Al is just 6.67 lower than that of raw aluminum pigments, indicating that encapsulation has less effect on the metallic appearance of aluminum pigments. Furthermore, there is no change in L-value of coating before and after dipping the sample in acid medium of (pH=1) for 24 hrs, revealing that the PA/SiO2/Al presents good anti-corrosion. Fourier transformation infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis proved that SiO2 and PA successfully encapsulated on the surface of aluminum pigments in turns.In order to simplify the encapsulation process and minimize the loss of metallic luster of aluminum pigments, organic-inorganic hybrid encapsulated aluminum pigments were further developed using siloxane groups modified acrylate resin and TEOS as precursors. Firstly, Siloxane groups modified acrylate resin Poly (Methyl methacryalte-n-Butyl acrylate-Vinyl trieth oxysilane (PMBV) was formed by co-polymerization of MMA, BA and VTES. When nBA:nMMA:nVTES=2:2:1, the amount of Initiator is 3% of total monomers, the reaction temperature is 110℃and the reaction time is more than 3 hrs, the conversion rate is up to 92.5%, and the product of polymerization is colorless and transparent with Molecular Weight of 3700 and Molecular weight distribution of 2.056. Outcomes of FTIR, nuclear magnetic resonance of H element (1H NMR), nuclear magnetic resonance of C element (13C NMR) and differential scanning calorimentry (DSC) analysis of resin demonstrate that VTES, MMA and BA copolymerized with each other instead of self-polymerized. The content of silicon in PMBV is about 3.89% according to the result of colorimetry. Then the hydrolysis-condensation product of PMBV and TEOS was studied by atomic force microscopy(AFM), FTIR, thermo gravimetric(TG)and nuclear magnetic resonance of Si element (29Si NMR). The results show that hydrolysis products of PMBV and TEOS have self-condensed and co-condensed with each other simultaneously in ethanol media to form homogeneous and transparent organic-inorganic hybrid materials. Variable angle XPS analysis shows that the contents of Si, O and C element have relationship with the thickness of hybrid films, indicating that the siloxane groups and the silicon have co-condensed with hydroxyl groups on the surface of aluminum in the hydrolysis - condensation process.PMBV composited with SiO2 encapsulated aluminum pigments (PMBV-SiO2/Al) were prepared by hydrolysis and condensation of PMBV and TEOS on the surface of pigments via sol-gel method using ammonia as catalyst and ethanol/H2O as dispersion media. FTIR, TG and XPS analysis of encapsulated aluminum pigments reveal that when the mass of aluminum pigments is 1.5 g, the amounts of ammonia and H2O are 3 mL and 3 mL respectively, the total amount of PMBV and TEOS is 13.1mmol(molars of Si), and the ratio of PMBV to TEOS is 1:0.45~1(molars of Si),PMBV and TEOS can form uniform and compact organic-inorganic hybrid layer on the surface of aluminum pigments. The as-prepared aluminum pigment shows good anti-corrosion and compatibility with resin. It is useful to enhance the corrosion resistance of PMBV-SiO2/Al by increase the amount of TEOS, which means that the anti-corrosion property of PMBV-SiO2/Al largely depends on SiO2. And the comparison of anti-corrosion of a variety of aluminum pigments also verifies this conclusion. Lightness value test shows L-value of PMBV-SiO2/Al decrease 0.24, stating clearly that the organic - inorganic hybrid film maintained the metallic appearance of aluminum pigments well. Peeling test demonstrates that the adhesion of PMBV-SiO2/Al in coating has been enhanced compared with that of raw aluminum pigments, which means the compatibility of PMBV-SiO2/Al with resin has been improved. However, the compatibility of PMBV-SiO2/Al is slightly poorer than that of PA/SiO2/Al.更多还原