纤维吸湿特性与加热卷烟专用再造烟叶涂布性能适配性研究

Investigation on moisture adsorption properties of fibers and their application in evaluating the coating performance of reconstituted tobacco for heated toboacco products

为考查纤维吸湿特性差异及其对加热卷烟专用再造烟叶涂布液吸收能力的影响,研究了5种植物纤维(亚麻纤维、草纤维、竹纤维、阔叶纤维、针叶纤维)、1种再生纤维(天丝纤维)结构及组成对其片基吸湿特性的影响,制备含有上述6种外加纤维的再造烟叶片基,并研究纤维吸湿特性与再造烟叶涂布性能的适配性。结果表明:1)6种纤维片基的吸湿特性有较大差异,其中天丝纤维吸湿特性最强,竹纤维次之,亚麻纤维最差;水分迁移过程中纤维片基的最大吸附速率和最大脱附速率均随着相对湿度的增加而显著增大。2)采用平行指数动力学PEK模型将纤维片基水分动态吸附-脱附拟合为快速和慢速两个过程,快速过程主导纤维片基中水分迁移行为,且随着相对湿度的增加,快速过程平衡吸水率变大,特征时间减小;慢速过程特征参数随相对湿度变化无明显规律。3)纤维微观结构形态、环境条件等因素与纤维吸湿特性密切相关,各纤维平衡吸水率与环境相对湿度呈正相关,与表观结晶度呈负相关,而温度对其影响较弱。4)外加纤维添加比例一定时,选择高吸湿特性纤维的再造烟叶片基对水和涂布液均具有较好的吸收性能。

To demonstrate the difference in moisture adsorption properties of fibers and the influence on the moisture adsorption properties of the five plant fibers(conifer,broadleaf,flax,grass and bamboo)and one regenerated fiber(Tencel),as well as the adaptability between moisture adsorption properties of fibers and coating performance of reconstituted tobacco for heated tobacco products,were studied.The results showed that the moisture adsorption properties of the six fibers were different.Tencel fiber performed the best,followed by bamboo fiber,and flax fiber performed the worst.The maximum adsorption rate and desorption rate of the fibers increased significantly with the increase of relative humidity during moisture migration.The parallel exponential dynamic model(PEK)was used to fit the moisture migration,it indicated that the progress consisted of a fast and a slow sorption procedure which occurred simultaneously.The fast procedure dominated the water migration behaviour in the sheet.As the relative humidity increased,the equilibrium moisture absorption content of the fast procedure increased and its characteristic time decreased.Meanwhile,the characteristic parameters of the slow procedure had no obvious rule with relative humidity.The micro-structure morphology,environmental conditions and other factors strongly influenced the moisture adsorption properties of fibers,the hygroscopic properties of fibers were positively correlated with the relative humidity(RH),negatively correlated with the crystallization of cellulose,while the temperature showed a weak effect on it.It was found that the reconstituted tobacco sheet showed outstanding coating performance including water and coating liquid with the application of excellent hygroscopic fibers under the condition of adding the same amount ratio during application.