Issue 34 — July 2003

Issue 34
Category		Titel		Authors
Newsletter		Emollients for hair conditioning products		Kakushi Doki, Shinji Taniuchi, and Koichi Masaki

Asian consumers increasingly require hair conditioning products which provide excellent effects on dry hair. Dry hair parameters such as smoothness (hair feel), softness, moisturizing, manageability and hair gloss are among the most important effects according to the customer 's perception. In order to match these requirements, various ingredients such as proteins, silicones and oils are combined with cationic surfactants to improve performance in hair care formulations. We have investigated different emollients with the expectation to select the ones covering maximum benefit on dry hair improvement. A selection from light to rich feel emollients was tested by considering sensory aspects (subjective test) as well as a friction analyzer (objective test).

Introduction

Hair conditioning products have been investigated especially for damaged hair, while hair color products have become popular in the market. The consumer's requirements are not only focussed on the repair of hair but also on the basic effects on hair, such as smoothness, softness, moisturizing and gloss. The combination of emollients often decides upon these basic effects on the hair. In the present report, we chose various kinds of emollients and studied how to select a suitable emollient for a targeted product.

The selection of emollients defines the sensory characteristics of the final skin care products. Investigations were performed on how to get a desired sensoric effect which can be adjusted through the principle of the spreading cascade during product development. (Figure 1). Each emollient is characterized by its spreading values. In this regard, it has to be kept in mind that a sophisticated skin care concept should impart a sensation of smoothness on the skin.

Figure 1: Balanced emollient mixture - Sensory cascading effect on the skin Enlarged version

Experiment methods

Emollients

The emollients employed and their properties are shown in Table 1.

Table 1: Emollients and their properties. Enlarged version

Rinse formulations were assembled by using the spreading value of emollients and were subjected to sensory assessment measurements.

Sensory assessment of hair tresses

Rinse formulations

A sensory assessment of hair rinse formulations with each of the emollients was conducted by using Asian hair tresses. After washing the hair tresses with lauryl ether sulfate (LES), the test sample was applied and washed off with enough warm water, and the hair tresses were dried and kept under constant temperature and humidity. The sensory parameters, smoothness, softness, moist feel, manageability and gloss, were evaluated on five degrees (-1, -0.5, 0, +0.5, +1.0) by six panels.

Test formulation:

Steartrimonium chloride	1 %
Cetearyl alcohol	4 %
Emollient	3 %
Water up to 100 (pH=5)

Emollients selected: Cetiol CC, Cetiol S, Cetiol ISL, Cetiol PEEH4, Cetiol J600, Monomuls 90-018.

Friction analyzer

A frictional assessment of emollients on hair was conducted by using a frictional analyzer (Kato-Tech Co., Ltd). After washing the hair with lauryl ether sulfate, 1% diluted emollient in isopropyl alcohol was applied on hair and the hair was dried and kept under constant temperature and humidity conditions. Then the average coefficient of friction (MIU : the value of an average friction coefficient during a movement of 2 cm) was measured before and after emollient application for comparison.

Half head test

A half head test was conducted at a salon studio by a beauty specialist. A Japanese panelist with damaged hair was used for the test. The following parameters were used:

Feeling at spreading: Concentrated feel, dispersion, smoothness,
Feeling at rinsing off: Easy of finger through hair, softening effect, remaining feel
Feeling of wet hair: Softening effect
Feeling at blow: Ease of combing
Feeling of dry hair: Ease of combing, softness, heaviness, manageability, smoothness, gloss

Results and discussion

A sensory profile was drawn up by calculating the average of the values obtained from all volunteers for each sensory parameter and were plotted on a graph. A visualization of tendencies which resulted from the sensory assessment tests is shown in Figures 2 a-e.

Fig. 2 a - e: Visualization of tendencies found by sensory assessment: Smoothness (a), softness (b), moisturizing (c), manageability (d) and gloss (e).
A Enlarged version	B
C	D
E

A summary of the properties of the emollients evluated by sensory assessment tests on hair tresses is provided in Table 2.

Table 2: Properties of emollients obtained by sensory assessment on hair tresses Enlarged version

Friction measurement of emollients on hair tresses

The MIU of hair tresses, treated with each emollient, were determined by a friction analyzer. The result is shown in Figure 3. Most of the emollients, having low spreading value, showed a decreased friction on hair. These MIU are equivalent to that of dimethicone.

Fig. 3: Friction of hair tresses treated with emollients Enlarged version

Correlation between MIU of emollients and rinse formulation (sensory assessment)

There is a good correlation between MIU of rich emollients and sensory assessment on hair. However, a rinse, which is formulated with light feel emollients, showed a high score against MIU of emollients. The particle size and structure of emulsions may influence it.

Rinse formulation design

A rinse formulation (please refer to Table 3), designed to improve hair smoothness, softness and manageability, was prepared by using the sensory profile of emollients and was evaluated by means of the half head test. A market product B was used as reference. As expected, the tested rinse formulation showed better dry hair smoothness, softness and manageability effects than the market product (Figure 4). This result suggests that a combination of emollients based on their sensory profiles will give a maximum benefit on hair improvement. The advantages of this concept are threefold: the investigated time is reduced, the concept is easy to formulate and a maximum benefit on hair is achieved.

Table 3: Rinse formulation Enlarged version

Fig. 4: Half head test results: Assessment on damaged hair. Market product B vs. rinse formulation: Enlarged version

Summary

The effects of emollients on hair were determined by sensory assessment and friction analyzer. Rinse products, formulated by using the sensory profile of emollients, gave excellent effects on hair.

In March 2003, this paper was presented by Kakushi Doki at the Personal Care Ingredients Asia Exhibition and Conference in Manila, Philippines.

Cegesoft, Cetiol, Cutina, Dehyquart, Eutanol, Gluadin, Lanette, Myritol, and Monomuls are registered trademarks of the Cognis Deutschland GmbH & Co KG.


Author

Kakushi Doki



Kakushi Doki has experience in the technical and sales divisions of Sumitomo Chemical Co. Ltd. Osaka, Henkel Hakusui Ltd., Ibaragi and Yuskin Pharmaceutical Co. Ltd. Kawasaki in Japan. In 2002, he assumed the position as Marketing Manager for Care Chemicals at Cognis Japan Ltd., Tokyo. As Regional Marketing Manager he is responsible for applications in hair, body and oral care for the Asia Pacific region.