Inger Mari Nygård Vold | August 30, 2016
On the Exilva blog, we will on regular basis bring you selected news from the latest application research both by the industry as well as academic sources. In this blog post, I’ve picked two examples from recently published patent applications, representing the use of MFC in material science and biomedical applications.
Please note that, for the sake of simplicity, I have used the term “MFC” throughout this text even if other names for the cellulose products have been used in the patent applications. If you would like to read a bit more about the confusing nomenclature, have a look at our blog post on this topic.
Why not use MFC in the adhesive of your multi-ply absorbent sheets?
MFC has many properties that make it a good performance enhancer in adhesives. Georgia-Pacific Consumer Products LP, Atlanta, GA (US) has recently filed a patent application (US2016/0215179A1) on a glue-bonded multi-ply absorbent sheet with a ply bonding adhesive containing polyvinyl alcohol and MFC.
The inventors have found that the rheological properties of MFC makes it a good additive for improving the glue properties, reinforcing the interface between the plies providing softer products with less glue. MFC is a shear thinning material and will modify the glue viscosity in a beneficial manner. Upon application of the glue, the viscosity will be low due to the shear forces applied, whereas the glue regains a high viscosity after application. When shear again is applied to marry the plies, the glue gets thinner enabling penetration into each paper web. After marrying, the glue will thicken to retain the wet bond with less pressure. MFC will also strengthen the interface between plies after drying. These properties make it possible to produce softer absorbent sheets with less glue. If you would like to read more about the rheological properties of MFC, have a look at our blog post “Important rheological properties of microfibrillated cellulose”.
Or as substrates for conformal bioelectronics?
MFC is a natural and biocompatible product with high mechanical strength making it a promising candidate for use as substrates in biological systems. Researchers and the Government of the United States of America, as represented by the Secretary of the Navy in the US, have looked at using MFC and MFC composites as substrates for conformal bioelectronics (US2016/0198984A1). The MFC substrates are able to adhere and conform to skin or other biological tissues while carrying thin-film electronic devices. The electronic devices can be used, e.g., for medical monitoring, diagnostic treatment, programmable drug dosing devices and motion monitoring.
Their results demonstrate that MFC substrates have several inherent properties that are beneficial compared to commonly used substrates. MFC has a high crystallinity providing high mechanical strength and flexibility to the carried electronic devices. MFC substrates are also able to transmit the chemical signals from the tissue to the attached sensor or device. Other important properties include permeability of water vapour, oxygen and other compounds needed to prevent tissue damage. MFC also has a high thermal and chemical stability, making it possible to use conventional electronic device fabrication processes which will degrade other types of substrates.
Increasing number of patent applications
These two examples on the potential use of MFC cover only a very small field of the opportunities. Since around the year 2000 there has been a steep increase in the number of patent applications filed regarding new materials, new processes for production and new application areas for MFC. Following the patent landscape related to MFC gives insight into the development work carried out worldwide, and demonstrates a lot of activities going on in very different fields. I hope this blog post has given you some new ideas and aroused your curiosity on MFC and potential use of this fascinating material.
