Abstract

Low consistency (LC) refining of (chemi-)thermomechanical pulp (TMP) provides an energy efficient alternative to high consistency refining for pulp property development. However, the benefit of LC refining is often limited by excessive fibre shortening, lower tear strength and a reduction of bulk caused by the refining process. In this study, microfibres produced by LC refining of TMP and kraft pulp fibres were investigated for their reinforcement potential in high freeness mechanical pulp. Primary pulp at 645 mL Canadian Standard Freeness was LC refined to different energy targets as a baseline for mechanical and optical property development. In contrast, the same primary pulp was reinforced with different microfibre types in ratios that yielded the same specific energies of the baseline LC refined pulp. The study revealed that at equivalent energies, the addition of TMP microfibres to the high freeness primary pulp displayed tensile development identical to the LC refined pulp, with significantly improved tear and bulk. The addition of kraft microfibre to primary pulp produced the highest tensile and tear strength but compromised light scattering. Additionally, all microfibre composites showed improved elongation, as opposed to no notable change in elongation with conventional LC refining. This investigation proposes an alternative, cost-effective approach for developing high bulk, high strength mechanical pulp by limiting the extent of second stage refining and using LC refined microfibres for pulp reinforcement. The high tear–high bulk open construction of the composite paper is likely to benefit boxboard and packaging applications.

中文翻译：

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低浓度精制木质纤维素微纤维：高松厚度、抗撕裂和拉伸机械浆纸的 MFC 替代品

 抽象的

（化学）热机械浆 (TMP) 的低浓度 (LC) 精炼为纸浆性能开发提供了高浓度精炼的节能替代方案。然而，LC精炼的好处通常受到精炼过程导致的纤维过度缩短、撕裂强度降低和松密度减少的限制。在这项研究中，研究了通过LC精炼TMP和牛皮纸浆纤维生产的微纤维在高游离度机械浆中的增强潜力。 645 mL 加拿大标准游离度的原浆经过 LC 精炼至不同的能量目标，作为机械和光学性能开发的基线。相比之下，相同的初级纸浆用不同的微纤维类型按比例增强，产生与基线 LC 精制纸浆相同的比能。研究表明，在相同的能量下，在高游离度原生浆中添加 TMP 微纤维表现出与 LC 精制浆相同的拉伸发展，并且撕裂度和松厚度显着改善。在原生浆中添加牛皮纸微纤维可产生最高的拉伸强度和撕裂强度，但会影响光散射。此外，所有微纤维复合材料的伸长率均有所提高，而传统 LC 精炼的伸长率没有显着变化。这项研究提出了一种经济高效的替代方法，通过限制第二阶段精炼的程度并使用 LC 精炼微纤维进行纸浆增强来开发高松厚度、高强度的机械浆。复合纸的高撕裂-高松厚度开放结构可能有利于纸板和包装应用。