基于耐沾污机理的低表面能路用水基热反射材料研制

Heat-reflective materials used for asphalt pavement were produced under the condition that asphalt pavement exacerbated the urban heat island effect for its high heat absorbance. Heat reflecting materials consisted of base materials and functional fillers; however, existing base materials have not enough stain resistance and are with too high a volatile organic compounds (VOC) level. In order to address this problem, firstly, this project analyzed the stain resistance mechanism of heat reflecting materials that applied on pavement, then for the idea of constructing low surface energy, hydrophobic core-shell emulsion and nanometer micro rough structure, water was chose as reacting medium, acrylic acid and fluorine monomer as reaction monomer to investigate the influence of emulsion system, polymerization process, and crosslinking system on film forming property of base materials and their reaction mechanism. Through characterization of their ontology and surface structures, performance evaluation, the formula of base materials and their preparation technology were optimized, thus a low surface energy, stain resisting fluorinated acrylate heat reflecting material was synthesized. Due to its heat reflecting properties and stain resistance, nanometer fillers were selected to explore the influence of monophyly or multiphyly particles on structure and working performance of heat reflecting materials, then determine the formula of base materials. To disperse nanometer filler into base materials, ultrasonic and chemical modification were used. When heat reflecting materials were applied in asphalt mixture, their temperature reducing effect, abrasion resistance, skipping resistance and weather endurance and stain resistance were evaluated. The prepared heat reflecting materials is expected to have a about 10℃temperature reduction which will effectively relieve the urban heat island effect.

沥青路面热反射材料针对路面吸热性大，温度升高加剧“热岛效应”等问题而产生。热反射材料主要包括基料和功能性填料，现有基料存在耐污性不足及有机物挥发物（VOC）较高等问题。对此，项目首先分析路用热反射材料耐沾污机理，以构造低表面能核壳乳液及纳米微观粗糙疏水结构为设计思路，选用水为反应介质，丙烯酸和氟单体为反应单体，研究乳化剂体系、聚合工艺、共聚物结构以及交联体系对基料成膜性能的影响及作用机理，通过对其本体、表面结构表征和性能评价优化基料配方及工艺，合成低表面能耐沾污型含氟丙烯酸酯基料；选择兼具热反射和耐污特性的纳米填料，对其在含氟基料中进行超声、化学改性分散，研究单系或多系纳米粒子对热反射材料表面及本体结构、性能的影响，确定路用水基含氟丙烯酸酯热反射材料配方；将热反射材料应用于沥青混凝土中，评价其降温效果、耐磨、抗滑、耐候及耐沾污性。拟制材料预期降低沥青路面温度约10℃，可有效缓解“热岛效应”。

由于沥青路面存在夏季易吸热温度升高，导致路面热稳性病害、加剧热岛效应等问题，具有降低路表温度的沥青路面热反射涂层逐渐受到关注。然而，现有基料存在耐污性不足及有机挥发物（VOC）较高等问题。针对上述问题，项目首先分析路用热反射材料耐沾污机理，以构造低表面能核壳乳液及纳米微观粗糙疏水结构为设计思路，选用水为反应介质，丙烯酸和氟单体为反应单体，研究乳化剂体系、聚合工艺、共聚物结构以及交联体系对基料成膜性能的影响及作用机理，通过对其本体、表面结构表征和性能评价优化基料配方及工艺，合成了低表面能耐沾污型含氟丙烯酸酯基料。其次，选用金红石二氧化钛为反射功能、气相二氧化硅作为填料和消光剂，研究填料种类、用量对涂层性能的影响。由于纳米材料极易团聚，因此进一步采用超声、化学改性等方法研究了颜填料的分散性；采用SEM观察TiO2、SiO2在涂层表面和断面结构中的分布状况，发现涂层平整性较好，TiO2、SiO2粒子能够均匀地分散于材料中，从而使涂层具有良好的降温和消光作用。采用动态接触角仪评价了含氟丙烯酸酯热反射涂层的疏水性能，发现涂层接触角高，污染物与涂层附着力较小，涂层防污性能提高，且耐溶剂性和耐水性良好。最后，评价了热反射材料在沥青混凝土路面中的降温性能、耐磨性能、耐候性和耐沾污性能。研究发现当沥青混凝土试件温度升至60℃时，有涂层的试件降温值最大可达13.1℃。采用车辙仪碾压后发现涂层具有较好的耐磨性；采用冲水装置进行耐沾污性试验后发现，涂层耐沾污等级为1级，沾污试验后反射率下降很小，表明其具有优良的耐沾污性能。耐候性试验发现，涂层降温效果有一定程度下降。采用含氟热反射涂料和不含氟的热反射涂料铺筑试验段，对比发现含氟涂料耐沾污性优于不含氟涂料。综上表明，含氟丙烯酸酯热反射涂料具有良好的降温效果和路用性能。