Dirt and soil on shiny surfaces, particularly on glass, are highly noticeable to consumers. Glass cleaners, with a market size of about $200 million in 2016,1 are generally a combination of surfactants, cleaning agents, solvents and other components such as fragrances and dyes. Hydrocarbon surfactants, such as sodium dodecyl sulfate, are commonly used in these cleaners. However, they tend to leave a hazy residue on glass after cleaning, also known as streaking. Also, they create foam, which is perceived by consumers as requiring more work to clean. Various commercial glass cleaners claim streak-free cleaning, which is difficult to achieve. Therefore, it is highly desirable to have surfactants in glass cleaners that can emulsify greasy soil and that can be easily removed without leaving a residual streak, thus providing a clean, streak-free and glossy surface.


Fluorinated surfactants (fluorosurfactants) are a high performing class of surfactants, due to their effectiveness at reducing surface tension and their short fluorocarbon chains (C2-C6) that don’t foam as much as hydrocarbon counterparts. Conventional fluorosurfactants with a linear chain of 6 fluorocarbons (C6), are generally synthesized by telomer chemistry, which is an oligomerization process that inevitably generates C8 fluorosurfactants as byproducts. However, C8, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), are already known to be persistent, bio-accumulative and toxic. In the US, many perfluorinated substances ranging from C6-C8 are the subject of use restrictions imposed by the Environmental Protection Agency (EPA), and even substances down to C4 chains are gaining the attention of state and federal regulatory agencies. In addition, regulatory measures for PFOA and PFOS are already in force on the international level. PFOA has been identified as substances of very high concern in Annex VI of European Regulation (EC) No. 1272/2008, and PFOS is listed as persistent organic pollutant in Annex B of the Stockholm Convention and is already banned. Thus, using C6 fluorosurfactants in household cleaners has the potential to carry health and environmental risks, and may face future restrictions in usage.


Tivida FL fluorosurfactants, offered by EMD Performance Materials, are synthesized by a fundamentally different process from telomer chemistry. They have a unique molecular design that features branched and ultrashort fluorocarbon chains (C2-C3). This feature makes them extremely effective at reducing both static and dynamic surface tension and have the potential of being less toxic and bio-accumulating. Here, an application example is shown where Tivida FL 2300, a branched C2 fluorosurfactant, is used as an additive in a generic glass cleaner formula. Its streaking performance is evaluated by the DCC-09 Guideline for Glass Cleaners.2 The results are then compared with the generic cleaner itself and one with a competitive C6 product.


Table 1 shows the three cleaner formulas used in this study. The generic cleaner, without any fluorosurfactants, serves as a control, while the other two have either Tivida FL 2300 or the competitive C6 product, whose loading was adjusted to have the same fluorosurfactant concentration of 0.06 wt% in the final formula. Per DCC-09 Guideline, the streaking test is performed by adding 1 g of the formula onto a piece of clean glass (2” by 4”). Next, a Grade-40 cheesecloth is used as a wipe applicator to spread the formula and clean the glass back and forth for 10 strokes without any downward pressure. After the glass dries, the streaking performance is rated on a scale of 1 to 7, with 1 being streak-free.


Figure 1 shows a photograph for the streaking performance of the three formulas evaluated via the above protocol. Among all, it is very clear that the one with Tivida FL 2300 shows the best streaking performance with a rating of 2, while both the control and the one with the competitive C6 product show obvious streaks with a rating of 7 and 5, respectively. The superior streaking performance of Tivida FL 2300 is a result of several factors. First, a low static and dynamic surface tension from Tivida allows better wetting and leveling of the liquid cleaner on glass surface, which leads to a fast and uniform evaporation after wiping. Also, it is our observation that the cleaner with Tivida generated less foam than the other two during application. As mentioned above, foaming would normally require more wiping for removal, and tends to leave residues if not completely removed.


In summary, Tivida FL fluorosurfactants are excellent, non-toxic and non-bioaccumulative wetting and leveling agents for household and industrial cleaners, which have a wide range of end applications, such as window cleaners, multi-surface cleaners and windshield fluid. 


Acknowledgement
Special thanks to Ceaso Hawkins, Carolin Klein, Craig Hughes, Gregory McCraw, Manuela Loch, Christoph Koerber, Reiner Friedrich, Qinyun Peng, Michelle Minix, Francesca Eifler, and Ursula Lehwald for their support of this work.


References:

1. Surface care in the US, Euromonitor International 2016
2. CSPA Designation DCC-09 – CSPA Cleaning Products Division Test Methods Compendium for Glass Cleaners

More information:
EMD is a business of Merck KGaA, Darmstadt, Germany, 1200 Intrepid Ave., Suite 300, Philadelphia, PA 19112. Contact the author: yang.wang@emdgroup.com; techemdtan@emdgroup.com