IDEAL FOAMING AGENT FOR YOUR PERSONAL CARE FORMULATIONS

AN IDEAL FOAMING AGENT FOR YOUR PERSONAL CARE FORMULAS: POLYALDO 10-1-CC

The need for mild surfactants in cleaning products is increasing day by day. Consumers are seeking alternatives to conventional surfactants known to irritate skin and cause damage to hair. As interest in "natural" chemicals grows, development of alternative surfactant technologies accelerates. In response to this need, Lonza developed Polyaldo™ 10-1-CC, a nonionic surfactant based on polyglyceryl ester technology. This naturally sourced polyglyceryl ester represents an excellent alternative for formulators due to its ability to improve foam quality despite its very low irritation profile. This article compares the foaming and surfactant properties of Polyaldo™ 10-1-CC with its irritation profile against commonly used general surfactants in the market. Foam comparison tests for the product were conducted using the KRÜSS RMFA, the first fully automated foam analysis instrument built to the Ross-Miles standard. Test results show that Polyaldo™ 10-1-CC polyglyceryl ester is a high-performance surfactant exhibiting low irritation profile on skin. In the personal care product market, products are available in many different product forms for consumer use. Products designed for cleaning, such as shampoos, body lotions, facial cleansers, hand cleansers and other cleaning systems, are considered an important part of daily routines, and therefore market demand for innovative cleaning products continues to grow.

Surfactant Basic Properties

In evaluating Polyaldo™ 10-1-CC polyglyceryl ester performance, two market standard surfactants were additionally included in the study to provide a reference framework. PEG-80 Sorbitan Laurate is known as a mild surfactant for skin; it is found in many mild cleaning products such as products designed for baby care and sensitive skin. Decyl Glucoside is an alkyl polyglucoside (APG) surfactant derived from plant-based alcohols. It is a good skin cleanser and provides excellent flash foam in cleansing formulations. The typical properties of the three surfactants are summarized in Table 1.

Table 1. Basic properties of Polyaldo™ 10-1-CC, PEG-80 Sorbitan Laurate and Decyl Glucoside.

In Vitro Epidermal and Epiocular Irritation Profile Study

Polyaldo™ 10-1-CC polyglyceryl ester was evaluated in an in vitro MatTek Epiderm™ Skin Irritation Test (SIT) against PEG-80 Sorbitan Laurate, a commonly used surfactant. To expand the scope of the study, Decyl Glucoside and Cocamidopropyl Betaine were added to the test. Buffered saline solution was used as negative control and 5% Sodium Dodecyl Sulfate (SDS) solution as positive control, and average tissue viability percentages were calculated through specialized software. A test sample with average tissue viability percentage of 50% or higher was considered non-irritating, while a test sample with average tissue viability percentage of 50% or lower was considered irritating. According to the results in Table 2, Polyaldo™ 10-1-CC polyglyceryl ester is classified as a non-irritating surfactant material. PEG-80 Sorbitan Laurate, known for its mild effect on skin and widely used in baby care products, was also classified as a non-irritating substance. Decyl Glucoside and Cocamidopropyl Betaine, frequently used in personal care applications, are classified as irritating.

Table 2. Comparison of Polyaldo™ 10-1-CC, PEG-80 Sorbitan Laurate and other surfactants (in vitro MatTek EpiOcular™ Irritation Test study results).

Polyaldo™ 10-1-CC polyglyceryl ester was evaluated in an in vitro MatTek EpiOcular™ eye irritation study against PEG-80 Sorbitan Laurate, a product widely used in market products, and Decyl Glucoside and Cocamidopropyl Betaine were added to the study to expand its scope.

EpiOcular™ tissue viability measurements were performed through methyl thiazol tetrazolium (MTT) uptake and reduction. Average percentage viability at each time point was used to calculate EO50 (exposure time); EO50 (exposure time) represents the time when EpiOcular™ tissue viability was reduced by 50% compared to control tissues. According to the results in Table 3, Polyaldo™ 10-1-CC polyglyceryl ester is classified as a surfactant causing mild eye irritation, while PEG-80 Sorbitan Laurate is classified as a surfactant causing minimal eye irritation, and Decyl Glucoside and Cocamidopropyl Betaine are classified as more highly irritating substances.

Table 3. Comparison of Polyaldo™ 10-1-CC, PEG-80 Sorbitan Laurate and other surfactants (in vitro MatTek EpiOcular™ Irritation Test study results).

Study on Foaming Properties - Foamability and Foam Structure

Experiments were conducted at two different temperatures, 25°C and 49°C, according to ASTM standard. For this purpose, the liquid receiver and tank volumes were preheated to the desired temperature before the instrument was filled. The double-walled glass column of the instrument was maintained at the desired temperatures via an external circulator to ensure constant liquid and foam temperatures throughout the experiment. For all three surfactants, solutions of 0.5 g/L in distilled water were prepared and measured using RMFA within 24 hours. Each sample measurement was repeated 3 times. Figure 1 shows a comparison of ASTM standard result values for three samples measured at temperatures of 25°C and 49°C. Error bars reflect standard deviations obtained from at least three consecutive experiments. At both temperatures, APG exhibited significantly higher initial foam volume and better foam stability than Polyaldo™ 10-1-CC polyglyceryl ester and PEG-80 Sorbitan Laurate.

Figure 1. Comparison of ASTM standard result parameters for all three surfactants at 25°C (left) and 49°C (right).

At 25°C, although APG can store twice as much liquid within the foam, at 49°C the foam density (i.e., wetness) of APG is only 50% higher than Polyaldo™ 10-1-CC polyglyceryl ester and PEG-80 Sorbitan Laurate. Again, when compared with PEG-80 Sorbitan Laurate, Polyaldo™ 10-1-CC polyglyceryl ester, while showing equal foam density at 25°C, shows significantly higher performance at 49°C. To summarize, compared to APG, Polyaldo™ 10-1-CC polyglyceryl ester exhibits slightly lower foaming properties in terms of initial foam height, foam stability and wetness, while at 25°C it performs clearly on par with PEG-80 Sorbitan Laurate and even better at higher temperatures. At 25°C the aging behavior and foam structure of Polyaldo™ 10-1-CC polyglyceryl ester perform nearly equal to and even better than those of PEG-80 Sorbitan Laurate.

Summary

The selection of surfactant in cleaning final product formulations is important. Changes in consumer needs, market demand and regulations regarding contents play an influential role in deciding what type of surfactant will be included in the formulation. Polyaldo™ 10-1-CC polyglyceryl ester targets the key trends guiding the cleaning market with the characteristic of having a low irritation profile while effectively cleaning skin. This naturally sourced polyglyceryl ester, produced from plant-based feedstock, contains no 1,4-dioxane by-products and is an effective alternative to PEG-based surfactants. It is thought that the beneficial properties of Polyaldo™ 10-1-CC polyglyceryl ester will also be beneficial in household and industrial applications where low irritation profiles are increasingly sought. Fitness centers, preschools and medical industries are markets where high cleaning properties despite low irritation are needed, and therefore Polyaldo™ 10-1-CC polyglyceryl ester could be included. Additionally, the ability of Polyaldo™ 10-1-CC polyglyceryl ester to provide a more "wet" foam may be useful for safety industries such as fire extinguishers.   Özge Yüksel Özel Technical Business Development Manager, Personal Care Azelis Turkey      

References V. Low, St. Benn, M. Mihhailova, M. Jönsson, Th. Willers, Ch. Kolano, A Naturally Derived Polyglyceryl Ester: The Best of Both Worlds, SOFW Journal, 10-2017