Rheology of high solids Microfibrillated cellulose and miner al suspensions at high shear rates

微原纤化纤维素（MFC）是一种木浆材料，其中原纤维束彼此部分分离，从而产生高表面积产品，其作为可持续增强材料引起了极大的兴趣。FiberLean Technologies Ltd开发了一种新颖、可靠和可扩展的工艺，通过在水中研磨各种纤维素物种和一系列不同的矿物类型来生产MFC;该产品是一种称为FiberLean的MFC-矿物复合材料。随着印刷和书写纸等级的下降，许多造纸厂米尔斯正在寻求将其图形纸机转换为生产挂面纸板或其他包装产品。用于包装和其它纸等级的白色可印刷顶层通常在与基层一起被压制、压制和干燥之前作为单独的片材生产。因此，制造这些双层纸需要额外建造一个完整的造纸机湿部部分，这是一个重大的改造和投资。这些多层等级的顶层通常包括具有10%- 20%填料的轻度精制硬木牛皮纸纤维，该层的主要目的是光学覆盖基层并实现适合于印刷的高亮度表面。这种昂贵的造纸机升级的解决方案是使用位于网上方的涂料涂布器在造纸机湿部部分的仍在固化的基层上直接涂布低固体含量（7.5%-10%）的低重量FiberLean涂料。这种新型涂料的矿物含量可高达80%，MFC用作粘合剂，防止白色层渗透到低固体含量的基底中。然后，可以使用现有的造纸机部件将这两层同时压制和干燥，从而以显著更低的成本投资将单层造纸机升级为双层可印刷纸等级。通过优化这种在造纸机湿部应用均匀的FiberLean层的方法，利用相同的原理可以有助于开发用于包装应用的新型水基可持续阻隔层。这些基于MFC的层可通过封闭原纸的高度多孔表面并允许改善阻隔涂层保持性而用作湿气、气体和油脂阻隔涂层应用的预涂层。这可以允许施加更轻的阻隔涂层重量，而不损害最终产品的目标性能。此外，光滑、低孔隙率的FiberLean板层本身可以作为水分和油脂的屏障，为该应用创造了许多可能性。

Microfibrillated cellulose (MFC) is a wood pulp material where the fibril bundles are partially separated from each other, giving a high surface area product that attracts great interest as a sustainable reinforcing material. FiberLean Technologies Ltd has developed a novel, reliable, and scalable process to produce MFC by grinding a variety of cellulose species in water with a range of different mineral types; this product is an MFC- mineral composite material known as FiberLean. With the decline in printing and writing paper grades, many paper mills are looking to convert their graphic paper machines to produce liner board or other packaging products. White printable top layers for packaging and other paper grades are conventionally produced as a seperate sheet before being couched, pressed, and dried together with the base layer. As a consequence, manufacturing these two-ply papers requires the additional construction of a complete paper machine wet-end section that is a major rebuilt and investment. The top layer of these multilayer grades typically comprises of a lightly refined hardwood Kraft fibre with 10%- 20% filler with the main objective of this layer being to optically cover tha base layer and achieve a high brightness surface suitable for printing. A solution to this costly papermachine upgrade is to apply a low weight FiberLean coating at low solids content (7.5%-10%) directly on the still consolidating base layer at the wet-end section of a paper machine using a coating applicator positioned above the wire. The mineral content of this novel coating can be as high as 80% mineral with the MFC acting as a binder holding the white layer from penetrating into the low solids content base. The two layers can then be pressed and dried simultaneously using the existing paper machine components upgrading single layer paper machines to two ply printable paper grades with a substantially lower cost investment. By optimising this methodology of applying an even FiberLean ply at the wet-end of a paper machine, the utilisation of the same principal can contribute in the development of new aqueous based sustainable barrier layers for packaging applications. These MFC based layers could be used as a pre-coat for moisture, gas and grease barrier coating applications by closing up the highly porous surface of the base paper and allowing an impovement in the barrier coating holdout. This could allow lighter barrier coatweights to be applied without compromising the target properties of the end product. Furthermore, the smooth, low porosity FiberLean ply can on its own act as a barrier for moisture and grease creating numerous possibilities for this application.