Evaluation and Control of Coated Paper Stiffness
Evaluation and Control of Coated Paper Stiffness
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涂布纸挺度的评价与控制
DOI：
10.2524/jtappij.51.635
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
F. Onabe
中科院分区：
文献类型：
--
作者：
Koji Okomori;T. Enomae;F. Onabe
通过测定涂层的杨氏模量来评价涂布纸挺度的改善。挺度是纸张在印刷过程中最重要的性能指标之一。复印机卡纸之类的故障往往是由于纸张硬度差造成的。在涂布纸的情况下，涂布层的杨氏模量对整个涂布纸的刚度有很大的影响，因为涂布层越外层，在弯曲模式下的应变越大，尽管其它机械性能通常由原纸层控制.从理论上，从材料力学角度讨论了单面涂布纸涂布层杨氏模量的计算方法.此外，Clark刚度的准确解释使得能够由Clark刚度计算涂层的杨氏模量。经验地，由Clark刚度和纯弯曲刚度计算的杨氏模量表明，（聚对苯二甲酸乙二酯）必须代替纸用作基材以获得涂层的真正杨氏模量，因为原纸，当仅用水润湿时，膨胀并且厚度增加，基重由于滞后而变得更高，并且涂层/原纸界面变得比原纸表面更粗糙。当使用未润湿的原纸的值进行计算时，它们导致不正确的杨氏模量。淀粉的配方改善了淀粉/SB-胶乳共混物膜的杨氏模量，这表明相同粘合剂组合物的涂层的杨氏模量将倾向于随着淀粉含量而变得更高。含有较短粒径的PP（塑料颜料）的涂层具有较高的杨氏模量，但至多与碳酸钙的杨氏模量相当。然而，PP的较低密度预期有利于抵抗其自身重量引起的弯曲。在双层涂布中，发现在顶侧上布置含有更多淀粉的较硬涂层可改善涂布纸的挺度。
Improvement of coated paper stiffness was evaluated by determining Young's modulus of the coating layer. Then effects of color formulations and double coating were examined.Stiffness is one of the most important properties of paper in printing processes. Troubles such as jamming in a copying machine often stern from poor paper stiffness. In the case of coated paper, Young's modulus of the coating layer considerably affects the stiffness of the whole coated paper because the more external layer, the higher strain in a bending mode though other mechanical properties are generally dominated by the basepaper layer.Theoretically, the method of calculating Young's modulus of the coating layer of a one-sided coated sheet was discussed in terms of materials mechanics. Besides, the accurate interpretation of Clark stiffness enabled to calculate Young's modulus of a coating layer from Clark stiffness.Empirically, calculated Young's modulus from Clark stiffness and pure bending stiffness showed that an impervious film such as PET (polyethylenetelephthalate) must be used as a substrate in place of paper for a true Young's modulus of a coating layer because the basepaper, when wetted with only water, swelled and the thickness was increased, the basis weight became higher due to hysteresis, and a coating/basepaper interface became rougher than the basepaper surface. They resulted in an incorrect Young's modulus when values of unwetted basepaper were used for calculation.Formulation of starch improved Young's modulus of starch/SB-latex blend film, suggesting that Young's modulus of a coating layer of the same binder composition would tend to become higher with the starch content. The coating layer containing the PP (Plastic Pigment) of the shorter particle diameter had higher Young's modulus, but was at most equivalent to that of calcium carbonate. However, the lower density of PP was expected to be advantageous to resistance to a bend by the weight of its own. In double coating, arrangement of a stiffer coating layer containing more starch on the top side was found to improve the coated paper stiffness.