胶矾水在熟化书画用宣纸中的应用机理探究

Study on application mechanism of alum gelatin solution curing Xuan paper in Chinese painting and calligraphy

为了揭示胶矾水熟化书画用宣纸的科学内涵,通过胶矾水固化性能、墨滴晕散实验揭示明矾在胶料固化及抗墨滴晕散中所起到的作用。利用扫描电子显微镜(SEM)、高场^(27)Al核磁共振波谱(^(27)Al-NMR)和红外光谱(ATR-FTIR)研究胶与矾在熟化宣纸时各自的作用及协同效应。最后,通过湿热老化实验探讨明矾的负面影响。结果表明:1)明矾作为促干剂加速了胶水凝聚固化;作为软化剂增加了胶料弹性。2)明矾也可作为助留剂,起到墨滴助留作用。施加胶矾水的宣纸抗墨滴晕散性能优于单纯的胶水或矾水;有胶无矾时,墨迹浮在纸上,存在大量微孔,易漏墨。3)SEM、^(27)Al-NMR和FTIR分析表明,胶和矾在提高宣纸憎水性及抗墨滴晕散性能方面可起到协同作用。明矾以单核物Al(H_2O)_6^(3+)、AlSO_4^+,高聚物Al_(30)([Al_(30)O_8(OH)_(56)(H_2O)_(24)]^(18+))等形式与明胶的羟基或羧基键合,形成的紧密网络结构加强了胶料的交联,提高了胶料的抗水性。同时,铝离子可起到桥联作用,将带负电的明胶粒子转化为带正电的明胶粒子,促使明胶微粒沉淀在带负电的纤维表面。4)明矾用量越大,湿热老化后酸性越强,纸张越脆,严重威胁纸张的寿命。因此,传统胶矾水在熟化纸张时可起到促干剂、软化剂及助留剂的功能,但用量越大,纸张酸化越严重,建议研发可替代胶矾水的新一代施胶剂。

In order to reveal the scientific connotation of alum gelatin solution who is widely used in curing Xuan paper, the solidification and ink droplets shading experiment were performed to investigate the roles of alum; the effect and synergistic reaction of glue and alum were studied by scanning electron microscope （SEM）, highfield ^27AlNMR spectroscopy （^27AlNMR） and attenuated total reflection infrared spectroscopy （ATRFTIR）; the negative impact of alum was discussed through damp and heat aging test. The results showed that：1） As a drypromoter, alum could accelerate the glue agglomeration and solidification; as a softener, alum could increase glue elasticity. 2） Alum could also be used as retention aid, played the role of ink droplet retention. When paper treated by alum gelatin solution, the performance of antiink droplets scattering was better than pure glue or alum; If only existed glue without alum, the ink would float on paper and it was easy to leak ink for numbers of pores in paper.3） SEM, ^27AlNMR and ATRFTIR results showed that the gum and alum had synergistic reaction in improving hydrophobicity and ink droplets scattering property. Form of Al（H2O）6^3＋, AlSO4^＋ and Al30（[Al30O8（OH）56（H2O）24]^18＋, alum bonded together with hydroxyl or carboxyl from gelatin. The tight network structure they formed could improve the crosslinking and waterresistance of glue. Meanwhile, as a bridging role, Al ions could transform negative gelatin particle into positive charge, prompt gelatin particles deposited on the negatively charged fibers. 4） The greater the amount of alum, the stronger the acid, the paper was more brittle after ageing. So it was a serious threat to the life of paper. In summary, the study showed that the traditional alum gelatin solution played the role of drypromoter, softener and retention aid, but larger amount of alum made paper serious acidification. At last, it is suggested to develop a new kind of sizing agent to replace alum gelatin solution used in prior process.