丙烯酸酯乳液文物保护材料耐老化性能评价

Anti-Aging Performance Evaluation of Acrylate Emulsion Used for Cultural Relics Conservation

水溶性的丙烯酸酯乳液是文物领域常用的保护材料,多用于壁画、彩画、骨质文物、漆木器文物的加固和粘接。使用最广泛的丙烯酸酯乳液类文物保护材料是由原罗门哈斯公司生产的Primal系列。商品材料如PrimalAC33、SF016、B60A、WS24和MC76等在国内外的文物保护修复实践中应用较多,但文献报道大多数是直接购买使用的修复案例,缺乏较为系统科学的性能评价研究。针对5种常用的Primal系列丙烯酸酯乳液文物保护材料的湿热老化性能和光老化性能开展研究,通过微观形貌、色差和光泽度等分析比较其耐老化性能,采用红外光谱追踪光老化过程中的分子结构变化和吸收峰强度,阐释其降解机理。实验结果表明,WS24和B60A的耐湿热性能较好,SF016耐湿热性能最差;AC33的颜色和失光率变化最明显。光老化测试发现,紫外光照射过程中所有的材料均发生了断链反应,另外AC33与MC76有内酯生成。经过4200 h光老化后,AC33、SF016、B60A和MC76的羰基指数(CI)均有不同程度的增大,羰基吸收峰强度(D_(t))降低了10%~15%。WS24的羰基指数下降非常迅速,羰基吸收峰强度降低了53%,是5种材料中耐光老化性能最差的。综合评价认为,B60A的耐光老化性能、耐湿热性能均较好,是Primal系列中耐老化性能最优的丙烯酸酯乳液文物保护材料。

Water-soluble acrylate emulsions are commonly used in cultural heritage conservation,mostly for the reinforcement and bonding of murals,colored paintings,bone relics and lacquerware.The most widely used acrylate emulsions for heritage protection are the Primal,formerly produced by Rohm and Haas.Commercial materials such as Primal AC33,SF016,B60A,WS24 and MC76 have been widely used in the conservation and restoration practice of cultural relics at home and abroad.However,most of the literature reports are restoration cases of direct purchase and use,and their is a lack of systematic scientific performance evaluation research.In this study,we investigated the hygrothermal and UV ageing performance of five commonly used Primal acrylate emulsions,comparing their ageing resistance properties through microscopic morphology,colour change and gloss,etc.Infrared spectroscopy was used to trace the molecular structure changes and absorption peak intensities during UV ageing to explain their degradation mechanisms.The results show that WS24 and B60A have better heat and humidity aging resistance,while SF016 has the worst performance during the heat and humidity aging test.AC33 showed the most obvious color and glossiness changes.UV ageing test revealed that all five materials underwent chain scission reactions during UV irradiation,and AC33 and MC76 had lactones formation.After 4200 h UV aging,the carbonyl index(CI)of AC33,SF016,B60A and MC76 increased to different degrees,and carbonyl absorption peak(D_(t))intensity decreased by 10%~15%.The carbonyl index of WS24 decreased rapidly,and the carbonyl absorption peak intensity decreased by 53%,which was the worst among the five materials in the UV aging test.According to the comprehensive evaluation,B60A has excellent resistance to UV and hygrothermal aging,and is the best Primal acrylic emulsion for cultural relic protection.