金属氧化物掺杂对水性UV聚氨酯涂料的性能影响

Influence of metal oxide doping on waterborne UV polyurethane coating

水性紫外光(UV)固化涂料因其节能高效、绿色环保的优势,受到广大消费者的青睐。然而,涂料中水的存在增加了涂层干燥固化时间,使其生产效率降低,是制约水性UV涂料规模化应用的关键技术瓶颈。本研究针对水性UV涂料前期干燥时间长的问题,受水下胶黏剂的快速固化机制启发,采用超声物理分散和均质乳化手段掺入纳米金属氧化物(NMO),实现快速吸水,促进树脂固化,制备了一种快干型水性UV涂料。金属氧化物快速吸水能够消耗涂料中的游离水,同时由于反应放热促使体系温度升高,可进一步加快水分挥发,双因素缩短涂料中水分向外迁移的干燥时间,此外,反应产物能够增强漆膜的力学性能。研究结果表明,当纳米金属氧化物添加量为1.2%时,涂层水分干燥效率提升最明显,干燥时间从2095 s/g降至1325 s/g,缩短约36.75%。当纳米金属氧化物添加量为0.8%时,改性漆膜力学性能得到改善,漆膜磨耗量降低28.09%,耐磨性明显提高,并且漆膜硬度由H提升至2H。此外,改变纳米金属氧化物配比不会对漆膜附着力造成明显的负面影响。本研究提出的纳米金属氧化物改性水性UV涂料策略操作简单且绿色环保,为快干型水性UV涂料的开发提供了新途径。

Waterborne UV coating is favored by most consumers because of its advantages of environmental protection,high efficiency,and energy conservation.Its drying curing process is divided into two stages,i.e.,the water evaporation and UV ultraviolet radiation.Before UV curing,the waterborne UV coating must go through the drying and water removal stage.The high evaporative latent heat of water leads to long time-processing and high energy consumption in this stage,which reduces the production efficiency and restricts the large-scale application of waterborne UV coating.In view of the problem of long drying time in the early stage of the waterborne UV coating,inspired by the rapidly curing underwater adhesive,the nano-metal oxide(NMO)was incorporated by the ultrasonic physical dispersion and homogeneous emulsification methods to prepare a quick-drying waterborne UV coating,which can achieve rapid water absorption and promote resin curing.Due to the strong hygroscopic property of fine particles,nano-metal oxide can absorb a small amount of water,and part of them can react with free water in the materials to form hydroxide.Thus it consumed the water in the system and shorten the drying time.At the same time,the system temperature increased due to the exothermic reaction,which further accelerated the water volatilization.These two factors shortened the drying time of moisture migration in the coating.Moreover,the reaction products were able to enhance the mechanical pro-perties of the coating film.To some extent,the wear resistance and hardness of the film were improved.The results showed that when 1.2% of the nano-metal oxides was added,the drying efficiency of the coating film had obvious improvement.The drying time was shortened by about 36.75%,decreasing from 2095 s/g to 1325 s/g.When 0.8% of the nano-metal oxides was added,the mechanical properties of the modified waterborne UV coating were improved.The coating wear consumption was reduced by 28.09% and the coating hardness was increased from H to 2H.Moreover,the increase of the nano-metal oxides content did not affect the coating adhesion.The strategy of nano-metal oxides modified waterborne UV coating was simple,green and environmentally friendly.This study provides a new available way for the development of quick-drying waterborne UV coating.