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该文研究了表面施胶淀粉对未施胶和未压光纸页的机械性能的影响。重点探讨纸页的淀粉施胶量对纸张弹性模量、破裂伸长率以及弯曲挺度的影响。该研究采用真空辅助注入装置将淀粉施涂于纸页上,在干燥风罩送出的热风下干燥。通过重复这一试验过程来获得一系列不同淀粉施胶量的纸张。为了消除水和纸张湿润再干燥过程对试验结果的影响,实验过程中以施加相对应水量的纸张作为参比样。结果表明,表面施胶淀粉提高了纸张横向弹性模量,而对纸张纵向弹性模量没有改善。在提高纸张弹性模量以及弯曲挺度的过程中,淀粉仅提高收缩势能;在纸页收缩受限制的情况下,这将会导致干燥应力的增大,从而增加了弹性模量并提高了弯曲挺度。然而,当纸页干燥收缩不受限制时(自由干燥),虽然弹性模量降低,但纸样的弯曲挺度还是有所提高。这是由于纸样厚度的增加弥补了弹性模量损失对挺度的影响。因此,施胶淀粉有2种方式影响纸张弯曲挺度:当纸张干燥收缩受限制时,淀粉通过增加干燥应力提高纸张弹性模量;当干燥收缩不受限制时,由于纸张厚度的增大而导致弯曲挺度的提高。在纸张实际生产过程中,由于纸张横向会有不同的收缩行为,因此,弯曲挺度的变化机理随整个纸幅横向收缩模式变化而不同。
This paper studies the effect of surface sizing starch on the mechanical properties of unsized and uncalendered paper. The paper mainly focuses on the influence of the amount of starch sizing on paper elastic modulus, elongation at break and bending stiffness. The study used a vacuum-assisted injection device to apply starch to paper sheets and dry them under hot air from the drying hood. A series of different amounts of starch sizing paper was obtained by repeating this test procedure. In order to eliminate the wetting and re-drying process of paper and water on the test results, in the course of the experiment to apply the corresponding amount of water as a reference sample. The results show that the surface sizing starch increases the transverse elastic modulus of the paper without any improvement in the longitudinal elastic modulus of the paper. Starch increases only the shrinking potential energy in increasing the elastic modulus of the paper as well as the bending stiffness; in the case of limited sheet shrinkage, this leads to an increase in the drying stress, thereby increasing the elastic modulus and increasing the bending Stiffness. However, when the drying shrinkage of the paper sheet is not limited (free-drying), the flexural rigidity of the paper specimen is improved although the elastic modulus is reduced. This is because the increase of the thickness of the paper makes up the influence of the elastic modulus loss on the stiffness. Therefore, there are two ways in which the sizing starch affects the bending stiffness of the paper: the starch increases the modulus of elasticity of the paper by increasing the drying stress when the shrinkage of the paper is restricted; when the drying shrinkage is not limited, the paper thickness is increased Increased bending stiffness. In the actual paper production process, due to the paper will be a different horizontal shrinkage behavior, so the bending stiffness of the mechanism varies with the entire pattern of transverse contraction mode changes.