冷涂料中微纳核/壳结构近红外反射彩色复合颜料调控原理及构效关系

Using of cool coating is an effective way to increase urban albedo, reduce building energy consumption and relieve urban heat island effect. The adjustment and control in near-infrared reflectance and color performance of pigment is an important issue to satisfy both insulation and color diversity of cool coating. In this study, the organic pigment with near-infrared transmittance and rutile TiO2 with high light reflectance are combined to fabricate a micro-nano core/shell composite pigment with high near-infrared reflectance. According to the relationship between material characters including dielectric constant and refractive index, and optical characteristic of composite pigment, a physical optical model is set up by finite difference time domain to control and adjust near-infrared reflectance and color performance of composite pigment. Based on analysis results, the adjustment mechanism is studied and a series of composite pigments are designed and prepared. Then the structure-functional relationships between the interface bonding strength, structure composition of composite pigment and their color performances, near-infrared reflectance are investigated, which was used to analysis the key influence factors for preparation of composite pigment with both excellent color performance and high near-infrared reflectance. The scientific significance of this study is to reveal the control and adjustment mechanism on the near-infrared reflective micro-nano composite pigment utilized in colored cool coating. Additionally, a method to design and prepare functional pigments is proposed.

“冷涂料”的使用是增加城市反射率，降低建筑能耗、缓解城市热岛效应的有效途径之一。颜料粒子近红外反射率及色彩特性的调控，是提高“冷涂料”隔热效率并兼顾色彩多样性的重要问题。本项目通过有机颜料近红外透过性与金红石型TiO2强反射特性的有机结合构建得到高近红外反射率微纳核/壳结构复合颜料，通过核/壳物质特性（如介电常数、折射率等）与光学特性间的关系，采用时域有限差分法构建调控复合颜料近红外反射率和色彩特性的物理光学模型，研究其调控原理并设计制备系列核/壳结构复合颜料。研究复合颜料界面结合力、结构构成与其色彩特性及近红外反射率的构效关系，探索出兼顾色彩特性和高近红外反射率颜料粒子构成的关键因素。本项目研究意义在于揭示用于“彩色冷涂料”的微纳结构复合颜料近红外反射率的调控机制，并探索一种功能颜料粒子从设计到实验制备的研究方法。

“城市热岛效应”引发的建筑物高能耗问题一直是国内外研究学者所关注的热点问题之一。研究表明，在建筑物表面和道路上涂刷“冷涂料”以增加建筑物和道路对太阳光的近红外反射率，是降低建筑能耗、缓解城市热岛效应的有效途径之一。然而，目前现有“冷涂料”主要是以浅色系为主，存在光污染、耐污性不足等问题。基于此，本项目以“冷涂料”中主要对太阳光反射物质“冷颜料”为研究对象，通过将酞菁蓝、酞菁绿等有机颜料的红外透过性与金红石型TiO2的强反射特性进行复合制备得到兼具高近红外反射率和良好颜色性能的核/壳结构彩色复合“冷颜料”。研究了酞菁颜料与金红石型TiO2的结合方式（疏水作用结合、偶联剂结合和不同静电引力结合）、二者复合比（10%-25%）、二者复合核/壳比以及其它制备工艺条件对制备所得复合颜料的近红外反射率及颜色特性的影响。结果表明，通过球磨作用力下的疏水作用力及偶联剂修饰下疏水作用力下制备得到的复合颜料在近红外区（1000-2500nm）具有较高的近红外反射，最高可达90%。而静电引力作用下制备得到的复合颜料在400-1000nm和1300-2500nm两个区域内的近红外反射率有所下降，但其颜色性能较好。最后，采用时域有限差分法（FDTD）对不同结构构成（不同核/壳比、不同TiO2粒径大小及不同颜料壳层厚度）复合颜料的光学特性进行了数值模拟研究。结果表明，酞菁颜料壳层厚度和酞菁/金红石型TiO2核/壳比对复合颜料近红外反射率起主要控制作用，且高核/壳比和较厚的酞菁颜料壳层厚度会使得复合颜料的可见光吸收波长发生明显红移。本项目研究成果揭示了核/壳结构彩色复合“冷涂料”的近红外反射率的调控机制，对彩色“冷颜料”开发和工业化制备具有一定的参考研究价值。