Mar. 17, 2022
Mild surfactants, in skin cleansing products, have grown steadily over the past decade. Mild surfactants provide low skin irritation and luxurious, creamy lather at the start of a wash. They are easy to rinse, yet squeak-free during the wash and have a soft, moisturizing and smooth afterfeel. Some of the available thickening techniques can achieve the target viscosity, but often the required use levels are so high that they may inhibit foaming or make the foaming process difficult.
Let's look at some of the challenges surfactants encounter in quality enhancement.
fatty alcohol ethoxylates
To achieve viscosity, the main thickening technologies available on the market are conventional thickeners or build-up thickeners. Conventional thickeners are typically high molecular weight water-soluble polymers that rarely contain hydrophobic groups such as xanthan gum or cellulose esters. The thickening mechanism comes from chain entanglement, hydrodynamic bulk and flocculation of the dispersed components. These high molecular weight polymers can occupy large amounts of water and restrict the movement of water, resulting in an increase in viscosity.
Another category is that of associative thickeners with hydrophobic and hydrophilic groups. They are represented by polyethylene glycol esters such as PEG-150 distearate, hydrophobically modified cellulose, hydrophobically modified polysaccharide conjugate thickeners, hydrophobically modified acrylate copolymers, or hydrophobically modified alkali-soluble emulsions ( HASE ). Polymer water incorporation forms hydrophobic interactions with surfactant micelles to build networks and achieve thickening. Compared to conventional sodium laureth sulfate (SLES) systems, mild surfactants have larger hydrophilic heads and are less likely to form surfactant micelles.
Viscosity consistency at different temperatures is another key performance requirement that formulators seek. As shown in Figure 2, you can see a comparative summary of commercially available rheology modifiers. Temperature affects the ability of water to bind and associate with interactions; therefore, polymers such as PEG-150 distearate or HASE exhibit a large variation between high and low temperatures, which results in a gelling effect at low temperatures and a significant reduction in viscosity at high temperatures. This is unacceptable to consumers, especially when using the product in different seasons. Charge repulsion, hydrophobic interactions and hydrogen bonding are the three main forces in the formation of polyacrylate cross-linked polymers; therefore it is not sensitive to temperature changes.
The sensory qualities of a body wash formulation are key properties that can be directly perceived by the consumer. Both cross-linked polymers-1 and -2 are able to enhance the creaminess of the foam with no adverse effect on the flash foam (foaming speed). However, usually the thickening agent will inhibit the foam volume as well as the foam speed to reach the required viscosity when added in a certain amount.
While thickening and viscosity consistency are the two main challenges for mild surfactant systems, high suspension of the formulation should never be overlooked when you want to expand your product line to develop compelling products with suspension capabilities or colored beads. Cross-linked polymers provide good suspending power compared to different rheology modifiers or thickeners.
SANCOLO is working hard to develop aesthetically pleasing, high performance mild cleaning products that provide the properties consumers expect. We have a capacity of 5,000 tons of non-ionic surfactants and 10,000 tons of polycarboxylic acid cement water reducing agents. Our production units are equipped with advanced ethoxylation external circulation system technology to handle larger monomeric nonionic surfactants and polycarboxylic acid cement water reducers.
If you need product list and quotation, please contact us promptly.