Boron compounds are effective ingredients, widely used in passive fire protection. In this work, epoxy-based hydrocarbon intumescent coatings, containing one of three boron compounds, zinc borate (ZB), ammonium pentaborate (APB), and boric acid (BA), were compared in thermal insulation performance at UL1709 heating conditions, char morphology, viscoelastic behavior, thermal degradation, and composition of the char surface layer. Results show that the char structure provides the most reliable indication of the thermal insulation performance. For APB- and BA-containing coatings, results were similar, while the ZB-containing ones showed a distinctive performance, especially the ones with the high borate concentration. The latter was attributed to the role of ZB in the intumescence and oxidation reactions, where the zinc, in the presence of boron, led to a compact char with less oxidation and high residual mass. In the char surface layer of one sample with a high concentration of ZB, a crystalline phase of boron trioxide, anticipated to be one important origin of the compact char, was detected. The present work contributes with an understanding of the essential roles of boron compounds, as well as the binder and pigment contents, and provides guidelines for seeking more sustainable and environmentally friendly alternatives.

硼化合物是有效成分，广泛用于被动防火中。在这项工作中，比较了UL1709加热条件，炭的形态下，包含硼酸锌（ZB），五硼酸铵（APB）和硼酸（BA）三种硼化合物之一的环氧基烃膨胀涂料。 ，粘弹性，热降解和炭表面层的组成。结果表明，炭结构提供了最可靠的隔热性能指标。对于含APB和BA的涂层，结果相似，而含ZB的涂层表现出独特的性能，尤其是硼酸盐浓度高的涂层。后者归因于ZB在膨胀和氧化反应中的作用，其中锌在硼的存在下，产生了一种紧凑的炭，具有较少的氧化作用和较高的残留质量。在一个含高浓度ZB的样品的炭表面层中，检测到三氧化硼的结晶相，该相预计是致密炭的一个重要来源。目前的工作有助于理解硼化合物的基本作用以及粘合剂和颜料的含量，并为寻求更具可持续性和环境友好性的替代品提供指导。