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

微纤维纤维素(MFC)是一种木浆材料，原纤束部分分离，具有高比表面积的产品，作为一种可持续的增强材料引起了人们的极大兴趣。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不同矿物类型的各种纤维素来生产MFC；该产品是一种名为FiberLean的MFC-矿物复合材料。随着打印和书写纸牌号的下降，许多造纸厂正寻求将其图形造纸机转换为生产衬板或其他包装产品。用于包装和其他纸张等级的白色可打印顶层通常在与基层一起烘干、压制和干燥之前作为单独的纸张生产。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，这是一项重大的改造和投资。这些多层牌号的顶层通常由经过轻微细化的硬木硫酸盐纤维和10%-20%的填料组成，这一层的主要目标是光学地覆盖基层，并获得适合印刷的高亮度表面。这项耗资巨大的造纸机升级的解决方案是，使用位于网线上方的涂布器，将低固体含量(7.5%-10%)的低重量FiberLean涂布直接涂在造纸机湿部仍在固结的基层上。这种新型涂层的矿物质含量可高达80%，MFC作为粘结剂，防止白色涂层渗透到低固体含量的基材。然后，可以使用现有的造纸机部件同时压制和干燥两层纸，将单层造纸机升级到两个层数可打印的纸张等级，成本投资大大降低。通过优化这种在造纸机的湿部应用均匀的FiberLean层的方法，利用相同的原理可以为包装应用开发新的水基可持续阻隔层。这些基于MFC的层可以通过封闭原纸的高渗透性表面并允许改善阻隔涂层的耐受性来用作防潮、阻气和阻油涂层应用的预涂层。这可以在不影响最终产品的目标性能的情况下应用更轻的阻隔涂层重量。此外，光滑、低孔隙率的FiberLean铺层本身可以作为水分和油脂的屏障，为这种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.