聚脲微球表面粗糙度及水性涂层消光性调控

Polyurea microspheres with different surface roughness for gloss control of water-based coating

以异佛尔酮二异氰酸酯(IPDI)为聚合单体,2,4-二胺基苯磺酸钠(MPDSA-Na)为亲水单体,SiO_(2)作为表面粗糙剂,通过沉淀聚合法在水/乙腈体系中制备了不同粒径和表面粗糙度的聚脲微球。将其用作水性聚氨酯涂层消光助剂,通过调节MPDSA-Na用量、IPDI用量和SiO_(2)用量等来控制微球的粒径和表面粗糙度,进而调节涂层的光泽度。结果表明:增加MPDSA-Na用量可减小微球的粒径并提高其在水中的分散稳定性,而提高溶剂中乙腈的比例和增加IPDI用量可增大微球的粒径;作为表面粗糙剂,提高SiO_(2)用量使微球粒径和表面粗糙度增大,在反应体系开始浑浊时加入SiO_(2),微球表面粗糙度最大;粒径介于1~2μm、表面粗糙度高的聚脲微球具有更好的消光效果,所制备水性聚氨酯涂层的光泽可调控至1.6°以下(60°入射角)。

Polyurea microspheres with different surface roughness and size are prepared by precipitation polymerization in water/acetonitrile system,using isophorone diisocyanate(IPDI)as monomer,MPDSA-Na as hydrophilic monomer and SiO_(2) as surface roughener,and the microspheres are used as the matting assistant for WPU coating.The particle size and surface roughness of microspheres are changed by adjusting MPDSA-Na and IPDI loading,the water/acetonitrile ratio and SiO_(2) loading,etc,so as to change the gloss of the coating.The results indicate that the increase of MPDSA-Na loading can reduce the size of microspheres and improve the dispersion stability of the microspheres in water,while adding the proportion of acetonitrile in the mixed solvent and IPDI loading can increase the size of the microspheres.As surface roughener,the increase of SiO_(2) loading can enhance the surface roughness and the size of microspheres.When SiO_(2) is added at the moment of the reaction system getting turbid,the surface roughness of microspheres reaches the maximum.Microspheres(1-2μm)with higher surface roughness have better matting effect,and the gloss of the prepared WPU coating can be adjusted to less than 1.6°(60°incident angle).