MFC offers excellent suspension properties

In personal care, the emphasis is on the first trend, namely the desire to have naturally-derived, biodegradable ingredients that are made by sustainable processes.1 In household care, the emphasis is on the second trend, that being the desire to create more concentrated products in order to reduce package size and, hence, reduce the cost of packaging, shipping, and the amount of waste that eventually ends up in landfills.2-5 These “green” trends are becoming evident throughout the world. Examples include the recent launch of the Clorox “Green Works™”6 household care line in the United States, as well as the recent trend of selling two-times and three-times concentrated versions of liquid laundry detergent. Suspension aids are often important ingredients in personal care and household care products. In personal care, suspension aids have allowed manufacturers to differentiate their products in both an aesthetic and functional way. For example, the shelves of stores are now stocked with eye-catching bodywashes, shampoos, and liquid hand soaps that incorporate decorative beads, glitter, or pearlescents as well as the suspension of more functional ingredients such as exfoliating or moisturising beads. In household care products, suspension aids are used to suspend abrasives, help stabilise emulsions, and improve cling. More recently, household care formulators are also making use of suspension aids to improve the aesthetic appeal of these products on the shelf.

Increased utilisation

Suspension aids that are naturally derived are present in the market and are being utilised more and more by both the personal care and home care formulators. Examples of these polymers include xanthan gum, carrageenan, various cellulose ethers, as well as natural clays. Though the interest in using these “green” ingredients is strong, it can be quite challenging to the formulator when it is considered that synthetic, petroleumderived suspension aids like Carbopol thickeners and other polyacrylates are so widely used, particularly in the personal care market. These synthetic products are extremely useful to provide good suspension and viscosity in a variety of formulations. In fact, these products are so versatile that it is unlikely that any one type of naturally-derived polymer could possibly mimic the entire performance range of these various synthetic polymers. In particular, it has been challenging to replace these synthetic suspension aids in surfactant-thickened products such as bodywash, shampoo, and liquid hand soaps. These polyacrylates-copolymers provide good suspension of insolubles while maintaining the “honey-like” viscosity of typical surfactant-thickened formulations. Using alternative, naturallyderived suspension aids like xanthan gum can provide sufficient suspension in these formulations but cannot re-create the honey-like surfactant rheology due to xanthan’s high pseudoplasticity. Further, the attempt to use surfactant-thickening in combination with xanthan gum or other biodegradable viscosifiers generally leads to a hazing of the formulation resulting in phase separation or precipitation of the suspension aid. In liquid detergents for home care, the use of suspension aids is relatively new but is likely to increase. This is because these formulations are becoming more concentrated and the demand is increasing for using more “green” biodegradable ingredients, many of which will be insoluble and, therefore, necessitating a suspension aid. This is particularly true for products such as dish soap and liquid laundry detergent. For example, zeolites are a green alternative to chemical detergent builders like phosphates, but they are completely insoluble and therefore would require a suspension aid when used in a liquid laundry product. Unfortunately, traditional, naturally-derived suspension aids do not generally have sufficient compatibility with these high levels of surfactants. In fact, even synthetic polymers are proving inadequate to provide suspension in these new, concentrated formulations. Current synthetic suspension aids are either not compatible with these increased levels of surfactants or are cost-prohibitive because of the high use levels required to give adequate suspension. Another problem with synthetic polymers is that they can increase the “pour” viscosity of the product and adversely affect its flow and dispersion into water by the consumer. Looking forward, suspension aids may even enable more efficient use of ingredients. An example of this is the desire to provide more efficient and effective enzyme activity to liquid dish and liquid laundry detergents. However, as liquid formulations continue to become more concentrated, it is more likely that the enzymes will be degraded by the high surfactant levels, formulation pH, or other denaturing effects while on the shelf. Encapsulating the enzymes could protect them from these effects, but a suspension aid would be necessary to maintain a homogeneous dispersion of these insolubles in the liquid detergent.