The influence of barrier pigments in waterborne barrier coatings on cellulose nanofiber layers
The influence of barrier pigments in waterborne barrier coatings on cellulose nanofiber layers
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DOI：
10.1007/s11998-021-00482-0
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发表时间：
2021-05-04
影响因子：
2.3
通讯作者：
Bousfield, Douglas W.
中科院分区：
文献类型：
--
作者：
Al-Gharrawi, Mohammed;Ollier, Rachel;Bousfield, Douglas W.
纤维素纳米纤维（CNF）层由于其氧气和油脂阻隔性能，在食品包装应用中具有巨大的潜力。然而，由于它们对湿气敏感，它们可能需要在具有水蒸气阻挡层的分层结构中使用。水性屏障涂料 (WBBC) 有潜力提供这种水蒸气屏障，但其在具有 CNF 层的纸张上的性能尚未在文献中描述。具有 CNF 层的纸张涂有三种不同的 WBBC 以及不同含量的两种不同阻隔颜料，以提高这些系统的水蒸气阻隔性能。这些系统的有效扩散系数是通过将数据拟合到两层扩散模型来获得的。使用有限元代码来预测在存在阻隔颜料的情况下水蒸气通过阻隔层的通量率。样品在生产中“堵塞”的危险以及油脂阻隔性能已经过测试。研究表明，纸上 CNF 层的存在可以提高水蒸气阻隔层的性能，在某些情况下，可以提高六倍。在WBBC中添加阻隔颜料，在低浓度下阻隔性能提高了15%，但随着颜料浓度的增加，阻隔性能下降。水蒸气透过率并没有像简单的理论模型和有限元计算所预期的那样降低到相同的数量级。这一结果可能与涂层中难以去除的细小气泡或涂布或干燥过程中产生的其他缺陷有关。阻隔颜料消除了对粘连的担忧。所有样品均具有良好的油脂阻隔性能。
Layers of cellulose nanofibers (CNF) have great potential to be used in food packaging applications because of their oxygen and grease barrier properties. However, because of their sensitivity to moisture, they likely will need to be used in a layered structure with water vapor barrier layers. Waterborne barrier coatings (WBBC) have the potential to provide this water vapor barrier, but their performance on paper with a CNF layer has not been described in the literature. Paper that had a CNF layer was coated with three different WBBC with various levels of two different barrier pigments to improve the water vapor barrier properties of these systems. The effective diffusion coefficient of these systems was obtained by fitting the data to a two-layer diffusion model. A finite element code was used to predict the flux rate of water vapor through the barrier layers in the presence of a barrier pigment. The dangers of samples "blocking" in production have been tested as well as grease barrier properties. The presence of the CNF layer on paper is shown to improve the performance of the water vapor barrier layer, in some cases, by a factor of six. Adding barrier pigment to the WBBC improves barrier properties at low concentration by 15%, but as the concentration of pigment increases, the barrier properties decrease. The water vapor transmission rate does not decrease to the same order of magnitude as expected from simple theoretical models and the finite element calculations. This result likely is linked to fine bubbles in the coatings that are hard to remove or other defects that are generated during coating or drying. Barrier pigments remove concerns around blocking. All samples had good grease barrier properties.