There is a strong need to disinfect and sanitise frequently touched surfaces. Exilva microfibrillated cellulose (MFC) is a bio-based structuring agent that can thicken household disinfectant and cleaning products at low to high pH, as well as with oxidising compounds.
How MFC can help thicken your advanced cleaning products
The CDC have listed the following as frequently touched surfaces: Tables, doorknobs, light switches, countertops, handles, desks, phones, keyboards, toilets, faucets, sinks, etc. (1)
Looking at any recommended list of disinfectants, you will notice that many of these household and industrial cleaners are strongly alkaline, highly acidic or contain oxidising agents. Secondly, the required contact time of common disinfectants varies from 1 to 10 min(2). This naturally creates challenges for formulators to find a suitable thickener which would allow easy spreadability and ensure required dwell time. In many cases, viscous gel or foam formulations are also preferred as they are considered safer to use, mainly by preventing any unwanted splashing.
Today we will look at how MFC allows you to manufacture stable gel formulations that are easy to apply and ensure sufficient contact time at low to high pH with oxidizing compounds such as hydrogen peroxide.
Today's challenges
The biggest challenge in thickening of highly acidic or alkaline products and oxidising compounds such as bleach is to find a stable rheology modifier. Most of the common rheology modifiers have a narrow pH working range and are often vulnerable to oxidising agents. The chemical instability of the compounds leads to a short shelf life of the end product. In addition to chemical stability, the rheology modifier should also provide a drip resistant profile for the formulation.
Current solutions
Many toilet bowl and bathroom cleaners tailored to remove scale and rust have a pH below 3 and are often based on hydrochloric acid. On the other hand, several cleaning products are based on sodium hypochlorite, typically stabilised with sodium hydroxide to pH 10-13. As can be seen in the list below, the amount of suitable thickeners is low (Table 1.), especially when you are targeting high pH formulations with oxidising agents.
| Compound | pH range | Oxidising agents |
| Carbomers | 3–13 | Some |
| Xanthan | 2–12 | Not stable |
| Cellulose ethers | 3–11 | Not stable |
| Magnesium aluminium silicate | 2–13 | Stable |
Table 1. Stability ranges of common thickeners used in cleaning products.
Thickening with MFC
Due to its insoluble nature, MFC shows considerably higher stability against chemical reactions than water soluble polymers. Figure 1. shows the complex viscosities of 1% Exilva in 5% sodium hydroxide (NaOH), 10% hydrochloric acid (HCl) and hydrogen peroxide (H2O2) after 24 hours and after 1 month storage. As can be seen from the figure, MFC effectively thickens these media and shows good storage stability.
Figure 1. Complex viscosities (Pas) of 1 wt% Borregaard Exilva MFC suspensions after 24 hours and 1 month storage at room temperature.
The high stability of Exilva MFC allows it to be used to thicken various home care and industrial cleaning products such as toilet bowl cleaners, bathroom cleaners, degreasers, metal cleaners, rust removers and car cleaners. The high chemical stability is also important in various other application fields such as coatings and adhesives.
In addition to the chemical stability, Exilva MFC provides exceptional rheological properties and outstanding compatibility with various compounds including surfactants. Due to high viscosity and high shear thinning, you are able to design formulations that are easy to spray and non-dripping (Figure 2.).
Figure 2. Anti-sag and spray properties of sprayed Exilva MFC formulation. The emulsion on the left hand side is a reference without Exilva MFC. The right hand side formulation contains 0.3% Exilva MFC which effectively prevents dripping on non-horizontal surfaces.
Summary
Exilva MFC offers a solution for those who are looking to simplify their formulations or have fewer additives on their shelf. In addition to the high performance and stability, MFC is a renewable choice for your challenging formulations, taking you one step closer to sustainable products.
