炭黑改性及对水性聚氨酯涂膜导电性的影响

Modification of Carbon Black and Its Effect on the Conductivity of Wa-terborne Polyurethane Coated Films

摘要:

采用原位乳液合成法，以炭黑（CB）为芯材、聚氨酯(PU)为壁材，制备表面均匀包覆聚氨酯的改性炭黑粒子（CB-PU），通过FTIR、TG、SEM、EDS等表征了改性前后粒子的结构和形态；对粒子进行分散性试验，结果表明，CB-PU在水中的均匀分散性与稳定性相比CB明显提高；将改性前后粒子与水性聚氨酯（WPU）涂料复合得到不同CB含量的导电涂料（CB/WPU、CB-PU/WPU），经涂覆、烘干得到导电膜材。研究结果显示，由于均匀包覆的壳层聚氨酯的亲水性，CB-PU能较为均匀地分散在WPU涂膜中；同时，由于CB-PU在涂膜中分散性的提高，极大地增大了涂料中导电粒子的网络密度和网络强度，CB-PU/WPU涂膜的导电性能显著提高；当保持体积电阻率约为3.3×103 Ω•cm时，CB质量分数由CB /WPU涂膜中的12 wt%下降到CB-PU/WPU 涂膜中的6 wt%；研究表明，通过在CB表面均匀包覆基体树脂层，可有效改进CB在基体中的分散性以及促进其导电网络形成。涂膜力学测试表明，添加改性后CB的涂膜断裂伸长较CB更优异，而强度有所下降。

Abstract:

The carbon black -polyurethane (CB-PU) particle with core-shell structure was prepared by the core material (CB) and shell material (PU) the in-situ emulsion synthesis method, The structure and the properties of the CB before and after modified were analyzed by FTIR,TG ,SEM and EDS; The dispersion test of the particles showed that the dispersion and stability of CB-PU in water were significantly improved than that of CB; Then the CB before and after modified was ultrasound dispersed in waterborne polyurethane (WPU) coatings to prepare conductive coatings with different CB content (CB/WPU and CB-PU/WPU), Finally, coating and drying the coating to prepare the conductive membrane. The study showed that the CB-PU can be uniformly dispersed in WPU coating films due to the hydrophilicity of the polyurethane which were completely coated on the surface of CB. The homogeneous dispersion of CB-PU greatly increased the density and intensity of the conductive network of conductive particles in coatings, which leads to a remarkable increase in the conductivity of the coating. In addition, when the volume resistivity was main-tained about 3.3×103 Ω•cm, the mass fraction of CB could dropped from 12wt %( in the CB/WPU film) to 6wt %( in the CB-PU/WPU film). The result indicates that it is an effective method to improve the dispersity of CB in the matrix and promote the formation of the conductive network by coating the matrix resin layer on the surface of CB. The mechanical test showed that the breaking elongation of the CB-PU/WPU was better than that of CB/WPU, while the breaking tenacity decreased.