Otto Soidinsalo | January 3, 2017
The first thing that usually comes to mind when hearing the word incontinence is diapers. These large pants almost impossible to hide and wear without someone noticing them. However, the product targeted for adult incontinence are in most cases pads, which are either in the form of underpants or attached to your underwear. Since people suffering from incontinence still want to live normal, active life, the industry is targeting thinner, discrete, but at the same time more efficient products to wear under regular clothes. So the question is, how will microfibrillated cellulose (MFC) fit into this picture?
Adult urinary incontinence is no longer a topic one should be ashamed to address. Although it`s commonly regarded a seniors' symptom, the fact is that even people in their 40s experience this - women and men alike. According to estimates, the sales of adult incontinence products will rise 48 percent from 2015 to 2020. Baby diaper sales will grow only 2.6 percent in the same period.
ABSORBENT PADS
A common core of an absorbent pad used in diapers or incontinence pads usually consists of two components: a superabsorbent material (SAP) and an absorbent matrix. One of the preferred superabsorbents is cross-linked sodium polyacrylate, typically in the form of particles. Correspondingly, the absorbent matrix is usually fluff pulp. The two-component core design is used primarily because many of the SAP materials are incapable of absorbing liquid at the same rate which the absorbent pads typically receive a liquid during use. The absorbent matrix will hold the liquid and release it to the SAP material at a slower rate. However, the liquid holding capacity of the fluff pulp itself is not high enough to work independently.
CHALLENGES
Although SAPs are capable of absorbing liquid up to several tens of times their weight, they suffer from a phenomenon called “gel blocking.” Gel blocking is a consequence of the swelling of the SAP particles. When the SAP particles start to swell on the surface of the absorbent pad, the channels or gaps between the SAP particles will close, preventing the liquid from entering to the SAP particles on the inner parts of the absorbent pad. That is why cellulose fibers (fluff) are mixed with SAP particles to minimize the potential particle to particle contact. The ratio between pulp and SAP material is typically 1 to 1. There is an option to decrease the amount of fluff pulp to produce thinner absorbent pads.
The properties of MFC - such as high surface area, water holding capacity, tolerance against ions - combined with a water based system, provides several opportunities for producing thinner and greener absorbents. The high surface area prevents gel blocking, enabling less fluff, resulting in thinner pads. At the same time, the water holding capacity can increase the efficiency of the absorbent pad, allowing less SAP.
FUTURE
A concrete commercial example of the possibilities for MFC in diapers was the launch of deodorant sheets, manufactured by Nippon Paper, used on their Hada Care Poise® and Acty® products. The sheets are based on TEMPO-oxidized cellulose nanofibers, containing metal ions that generate deodorant and antibacterial effects.
As the commercial activities around MFC and cellulose nanofibers increases, it is likely that we will see more compelling solutions shortly. Maybe one day we will have a useful absorbent article that is based completely on cellulose and renewable products – a greener option for the growing market.
