| Search | Feedback | Contents | Deutsch |
 |
| Issue 35 |  |
|||
| Printable version | ||||
| Category | Titel | Authors | ||
| Newsletter | Polymers and active ingredients suitable for the development of shampoo formulations | Werner Seipel, Peter Hössel, Norbert Boyxen, Wolf Eisfeld |
Cationic polymers are essential raw materials for shampoo formulations. To achieve a controllable conditioning effect in shampoos today, it is of major importance to incorporate the right polymer which has an adequate concentration in the formulation. This article will demonstrate the various possibilities to develop formulations and to improve their performance.
Damaged hair which requires caring treatment is characterized by mostly negative charge centers on its surface (Figure 1). It may thus be assumed that there is a strong affinity between actives with a positive charge (e.g. quaternary ammonium compounds) and the hair. In conventional shampoo formulations, however, anionic surfactants are applied which provide the right ratio between the foaming and cleansing effects and a high dermatological compatibility. Ingredients such as alkyl ether sulfate form a neutral salt with cationic substances which, in excess of the ether salts can be clearly solubilized. In general, there is no strong affinity between these complexes and the hair. It cannot be stated that their behavior on the hair is ineffective because they may deposit or penetrate during application. This is due to the dilution effect.
When large molecules are applied which have a structure characterized by identical repeating units, a volume extension is achieved which protects individual cationic charges on the molecule. Thus, complexes are obtained which have a close affinity with the hair. In dependence of the molecule size, structure and degree of cationization, they have an influence on the hair smoothness and electrostatic repulsion. For the consumer, this becomes obvious in that he has a reduced combing work.
Measurement of combing force
To evaluate the combing force as a performance property of the hair in an objective way, combing tests were carried out on wet and dry hair tresses. From a technical point of view, this process rather complex and may be evaluated in various ways, although it appears to be relatively simple for the consumer.
Combing work = integral of a force-distance-curve
Maximum combing force = peak value of combing force
Figure 2 (wet and dry combing curves) demonstrate the course of the forces which have to be applied over a distance (1; 2) (5; 6).
Table 1 gives a list of the cationic polymers used in test formulations.
INCI Names of the cationic polymers: Polyquaternium-7; Polyquaternium-10; Polyquaternium-44; Guar Hydroxypropyl Trimonium Chloride.
Wet combability
In a shampoo formulation composed of sodium laureth sulfate (SLES), betain and coco glucoside, an active substance of 0.2 per cent of the various polymers was incorporated. For this test, 20 hair tresses were previously damaged by bleaching and perming. After this, the initial combing work of the tresses (=0 per cent) was measured and treated with the various shampoos.
For all substances investigated there was a change in the combing work the hair became loaded with polymers. With the exception of polyquaternium-7, the combing work was reduced (see Figure 3). The strongest effects were achieved with polyquaternium-44 in all measurements performed. Minor differences were observed when compared with guar hydroxylpropyl trimonium chloride and polyquaternium-10. The increase in combing work achieved with polyquaternium-7 may be attributed to the fact that the initial values (combing forces) of the damaged hair were not high enough or perhaps varied strongly. It is difficult to standardize hair as an object for measurement. In consideration of these facts, it is a rather complex matter to make evaluations, even though this may not appear so when looking at the diagram. Nevertheless, combing force measurement offers an opportunity to objectively an isolated performance criterion. An improvement of the combing properties is generally referred to as the two-in-one effect.
Dry combing work
Moreover, it is possible to measure the dry combability of the hair tress after drying it. There are two options: to evaluate the hair tress with continuous accumulation of electrostatic charge, or in a continous discharge mode. In the evaluation of the dry combing work it is important to give an exact definition of the desired effect because an increase of the combing force may have a positive influence on the hair's stylability. Reduced combing work leads to easy combing, but the hair's smoothness may, however, lead to a decreased hold.
Electrostatics
If the electrostatic charge is measured separately, we obtain information on a possible flyaway effect which is undesirable. Hair which is statically charged, is not stylable because the charge distribution on the surface causes it to arrange itself in a position sticking out from the head. In general, cationic polymers increase the electrostatic charge of the hair.
Table 2 gives a number of examples for formulations which were tested by using various measuring techniques. The results and their interpretation show which possibilities may be derived from varying the formulation and the methods applied.
Formulations with polyquaternium-44 and various surfactant bases
A standard formulation, which only varies in the surfactant ratio, was chosen. With an increasing content of APG (alkyl polyglycoside, Plantacare 818 UP), the SLES:betain proportions were reduced to washing active substance to achieve a constant content.
With 7 per cent polyquaternium-44 (0.5 active substance in the formulation), a constant content of cationic polymer was adjusted. A major investigation criterion was to test the interplay between the cationic polymer and the optimal surfactant combination (3).
The results of measurements of the wet combing work and the wet combing force perfomed with various APG formulations are shown in Figures 4 and 5 show that the combing work or the combing force required is reduced by polyquaternium-44. The varying uses of surfactants have no palpable effect on the combing behavior, nevertheless, there is a tendency to be observed in the resulting bar charts. There was only a minor change in the adsorption behavior of the cationic polymer.
Dry combing work measurements show a continuous increase in the test results (Figures 6 and 7).
In contrast, the combing force (peak combing force) remains at a constant level. This may mean that the care ingredients are distributed over the entire hair and that no irregular combing force occurs.
Since the combing work increases with a rising APG content, an effect on the stylability may be supposed here (4).
The electrostatic charge has increased in the four investigated products (see Figure 8). Only further tests may show if this criterion will be negatively evaluated as flyaway effect. Subjective evaluations were carried out in sensory assessment tests.
Sensory Assessment
Sensory assessment is a test method which allows an objective evaluation of complex applications by considering individual criteria via a semi-objective evaluation (7; 8; 9). Individual criteria are evaluated during an application with a trained expert group of at least 10 persons. In contrast to mere combing work, the results allow scientists a comprehensive view while simultaneously reducing objectivity. It is further possible to evaluate effects in a creative way and to make a list of the individual product properties.
Figure 9 demonstrates the changing effects observed on dry hair.
When formulations were evaluated by means of sensory assessment, the placebo formulation 01/114/5 was taken as standard and represents the 0 line. While the bar on the left (yellow) shows a deterioration, the bar to the right (blue) shown an improvement of the effects in the test product. The results demonstrate how the combinations of surfactants influence the various evaluation criteria. A general evaluation led to the following conclusion: All four formulations displayed particularly good properties with regard to conditioning effect and foaming behavior (sensory assessment on wet hair). On hair treated with polyquaternium-44, a strikingly fine-porous, creamy foam developed. In further individual creative evaluations, hair was described as follows:
Good feel
Very soft
Smooth
Cuddly straight and
Yet very strong
Furthermore, a sensory assessment test was performed on dry hair, using various APG formulations (see Figure 10). All three test results demonstrate that -- next to the cationic polymer which was applied in all formulations in same amounts -- the composition of surfactants is a major contributor to the hair performance. At a concentration of 1.5 percent coco glucoside (Plantacare 818 UP), major critera such as combing work, feel and stylability could be improved. It was clearly recognized that, in the first formulation, these effects were not very strong yet and that they turned into negative values in the third formulation.
Experience has shown that the effects we observed are not generally transferable to other polymers. Due to the difference in polymer structures, further performance criteria have to be adjusted. An improvement in combing performance may, for instance, be observed when using APG and polyquaternium-10. It was possible to achieve a comparable or even slightly better conditioning effect on the hair by reducing the amount of polymer. This is of economical importance for the formulator.
Formulations with glycol distearate compound (wax dispersion) and polyquaternium-44
In further tests, the properties of shampoo formulations were tested in combination with polyquaternium-44 (Luviquat Care) and a wax dispersion. Table 3 shows the formulations used.
A strong affinity between the wax dispersion based on glycol distearate (Lamesoft TM Benz) and the hair was found. This may be attributed to the particularly small particle size of the wax dispersion of approximately 3 µm (10). This affinity may be even further increased when using a polymer with a cationic charge.
The results observed for formulations 1 and 4 show a decrease in the combing work (Figures 11a and b), which remains constant if the composition polymer/wax is changed. It is thus possible to establish optimal formulations for various hair types with the right composition. Wax particles are effective care ingredients for long and strongly damaged hair. For short and very thin and fine hair the most favorable care effect is achieved with a reduced amount of wax. If the amount applied is too high, the hair appears to be loaded. An accumulation or a buildup effect is not observed even at repeated applications.
The sensory assessment tests results (Figure 12) confirm the good results achieved in the combing work. The combing work of the hair tips was significantly improved in formulation 3. All further criteria showed a more or less strong deterioration by comparison with the standard formulation without the wax dispersion. Since the results only represent a variation to the standard (placebo), they may not be generally evaluated as poor.
Summary
The experimental results indicate that cationic polymers have various strong effects on the hair. Polyquaternium-44 is a highly effective active ingredient which, together with the surfactant base, may achieve optimal hair effects. Thus, stylability and hold of hair may be significantly improved in combination with coco glucoside. The creamy foam structure of the formulations was very noticable. In combination with a fine-dispersing glycol distearate significant increases in the conditioning effect (two-in-one-hair effects) are possible. All improvements described may be felt by the consumer and are reproducible.
Remarks
1) Plantacare 818 UP: INCI-Name: Coco Glucoside
2) Lamesoft TM Benz: INCI-Name: Glycol Distearate (and) Coco Glucoside (and) Glyceryl Oleate (and) Glyceryl Stearate.
Plantacare and Lamesoft are registered trademarks of Cognis Deutschland GmbH & Co. KG.
References
1) P.Hössel: Prüfmethoden für polymere Haarkonditionierer; SÖFW-Journal, 1994, 120.J, 847-851
2) P.Busch, K.Thiele: Eigendynamische Effekte an Haaren: Beiträge zur Methodik der Kämmbarkeit; Ärztliche Kosmetologie; G.Braun Verlag, 1979, 9.J, 305-310
3) Fachgruppe Haarbehandlungsmittel der DGK: Einfluss von Co-Tensiden und Konditioniermitteln in Shampoos; SÖFW-Journal, 1999, 125.J, 46-54
4) P.Busch, H.Hensen, H.-U.Krächter, H.Tesmann: Alkyl polyglycosides, their use in cosmetics; Cosmetics and Toiletries Manufacture Worldwide; 123 - 129
5) P.Busch: Subjektive und objektive Methoden in der Haarkosmetik; Ärztliche Kosmetologie; G.Braun Verlag, 1989, 19.J, 270-315
6) P.Busch, Fh.Förster, H.Hensen, Th. Müller-Kirschbaum, H.Tesmann: Subjektiv / objektiv-Bewertung kosmetischer Effekte; Ärztliche Kosmetologie; G.Braun Verlag, 1990, 20.J, 498-502
7) W.Boucsein, F.Schaefer, M.Kefel, P.Busch and W.Eisfeld: Objective emotional assessment of tactile hair properties and their modulation by different product worlds; Int. Journal of Cosmetic Science; 2002, 24, 135-150
8) P.Busch, Th.Gassenmeier: Sensory assessment in the cosmetic field; Parfümerie und Kosmetik 1997, 78.J, Nr.7-8
9) P.Busch, W.Eisfeld: Mass customisation and sensory assessment; SÖFW-Journal, 128.J, 3-2002
10) W.Seipel, C.Nieendick: Ester (Glyceride) with Care Effects for Skin and Hair; SÖFW-Journal, 128. J, 5-2002 und
http://www.scf-online.com/english/29_e/gmo29_e.htm
Author
Werner Seipel
Werner Seipel joined the cosmetic industry in 1980, after completing his professional training as a chemical engineer. He started out at the laboratories for applied chemistry at Lingner & Fischer, Germany. Since 1989 he has been head of a laboratory for applied technology and in charge of developing new raw materials in the field of hair and body cleansing products at Henkel, Düsseldorf.
With the formation of Cognis Germany at the end of 1999 he took over responsibility for application and technical services in the cosmetic market segments Hair, Body, Oral Care in the Care Chemicals Division.
Remarks
These findings have been the result of a cooperation between P. Hössel (BASF Aktiengesellschaft) and W. Seipel, N. Boyxen and W. Eisfeld (Cognis Deutschland GmbH & Co. KG).
The article has already appeared in German language:
W. Seipel, P. Hössel, N. Boyxen, W. Eisfeld, Polymere und geeignete Wirkstoffe für die Entwicklung von Shampoo-Formulierungen; SÖFW-Journal, 2003, 129. J., 69-76.
top
October 2003