Chemithermomechanical pulp (CTMP) is often used in central layers of multiply paperboards due to its high bulk and strength. Such a CTMP should consist of well-separated undamaged fibres with sufficient bonding capacity. The basic objective of this work is to optimize process conditions in low-consistency (LC) refining, i. e. to select or ultimately develop new optimal LC refiner filling patterns, in order to produce fibrillar fines and improve the separation of fibres from each other while preserving the natural fibre morphology as much as possible. Furthermore, the aim is to evaluate if this type of work can be done at laboratory-scale or if it is necessary to run trials in pilot- or mill-scale in order to get relevant answers. First stage CTMP made from Norway spruce ( Picea abies ) was LC refined in mill-, pilot- and laboratory-scale trials and with different filling patterns. The results show that an LR1 laboratory refiner can favourably be used instead of larger refiners in order to characterize CTMP with regard to tensile index and z-strength versus bulk. A fine filling pattern resulted in CTMP with higher tensile index, z-strength and energy efficiency at maintained bulk compared to a standard filling pattern.

中文翻译：

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针对高强度和高体积的CTMP的低浓度精炼：填充方式和试验规模的影响

化学机械纸浆（CTMP）由于其高松密度和强度而常用于多层纸板的中央层。这种CTMP应由分离良好且具有足够粘合能力的未损坏纤维组成。这项工作的基本目标是在低浓度（LC）精炼中优化工艺条件，即 e。选择或最终开发新的最佳LC精制机填充方式，以产生原纤细粉并改善纤维彼此之间的分离，同时尽可能保留天然纤维的形态。此外，目的是评估是否可以在实验室规模上完成此类工作，或者是否有必要在中试规模或工厂规模下进行试验以获得相关答案。由挪威云杉（Picea abies）制造的第一阶段CTMP在工厂进行了LC精制，中试规模和实验室规模的试验，并具有不同的填充方式。结果表明，可以使用LR1实验室磨浆机代替大型磨浆机，以表征CTMP的拉伸指数和Z强度与体积的关系。与标准的填充图案相比，精细的填充图案导致CTMP在保持体积的情况下具有更高的拉伸指数，z强度和能效。