scf-online.com | Issue 29 | Hispagel - Glyceryl Polyacrylate based Thickeners

Issue 29
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Category	Titel	Authors
Show Case	Hispagel - glyceryl polyacrylate based thickeners as new skin care ingredients with excellent moisturizing properties	Marta Torres, Franscsco Fabra

Hispagel polymer gels (1) are thickeners based on glyceryl polyacrylates. They are multi-functional and allow product formulators to develop high-performance cosmetic products in a fast and easy manner. They have vegetable and synthetic raw material bases.

*Table 1: Hispagel polymer gels - Appearance, pH-value and viscosity parameters of Hispagel 200 and Hispagel L**
Product	Appearance	pH (100%)	Viscosity (cP), 10% in water, #5, 20 rpm, 25ºC
Hispagel 200	Transparent, colorless jelly	4.7 - 5.5	12000 - 15000
Hispagel L	Transparent, colorless jelly	4.7 - 5.5	14000 - 17000

Moisturizing properties:

Hispagel polymer gels are excellent moisturizers. Corneometric measurements showed that they keep the skin perfectly hydrated even 7 hours after application. The moisturizing properties of Hispagel 200 are shown in Figure 1.

Figure 1: Moisturizing properties of Hipagel 200

Ratio viscosity/concentration:

Hispagel polymers have excellent moisturizing and thickening properties. They are ready for use, have a very good reproducibility in the final formulation and require no neutralization. Hispagel polymers are crystal clear and are thus suitable for application in transparent products. The viscosity of Hispagel L and Hispagel 200 is shown in Figure 2.

Figure 2: Hispagel — Viscosity versus Concentration

Ratio viscosity/pH:

Figure 3 shows the viscosity/pH ratio of Hispagel 200. The maximum stability is found in the area between pH 5 and pH 11.

Figure 3: Viscosity/pH Ratio of Hispagel 200

Compatibility with ethanol:

The compatibility of Hispagel 200 with different amounts of ethanol is shown in Table 2. The highest ratio of ethanol/water compatible with Hispagel 200 is around 30 percent.

Table 2: Compatibility of Hispagel 200 with different amounts of ethanol
Ratio ethanol/water	Hispagel 200 (g)	Water (g)	Ethanol (g)	Appearance	Viscosity (cP)
0	10	90	0	Clear	9200
20	10	72	18	Clear	8100
40	10	54	36	Clear	4800
60	10	36	54	Cloudy	Breaks
80	10	18	72	Precipitation	Breaks
100	10	0	90	Precipitation	Breaks

Summary: Properties of Hispagel polymer gel

Excellent thickening properties

Excellent moisturizing

Crystal clear transparency

Excellent water solubility

Emulsion stabilization

Good suspension properties

Excellent temperature stability

Very skin compatible

Excellent pH stability in the range 5 to 11

Ethanol compatibility up to 35 %

Formulating with Hispagel

Transparent gels

The production of hydrophilic polymer gels is a time-consuming operation which usually requires special equipment such as high-shear stirrers. A constant and reproducible viscosity in the final product is not easily obtained. Hispagel makes the production of cosmetic end products much easier because of its immediate and excellent water solubility. Water has just to be slowly added into Hispagel while stirring at low speed in order to avoid air incorporation.

When incorporating active substances into Hispagel systems they should be soluble in water/glycerin so that the mixture does not become cloudy. If ionic components are used, the viscosity may decrease.

Because of its good suspending properties Hispagel is an excellent choice to disperse encapsulated products such as Primasphere (2) and Primasponge (3) which are carrier systems based on chitosan carrying active ingredients such as vitamin A and menthol. Small amounts of lipophilic substances as preservatives or perfume can be easily solubilized with no influence on the transparency. An example of such applications is given in Table 3 which shows a formulation for a transparent cooling gel for legs.

Table 3: Transparent cooling legs gel

Phase	Component	INCI	%	Function
I.	Hispagel 200	Glycerin (and) Glyceryl polyacrylate	25	Moisturizing gel
	Water, de-ionized	Aqua	ad 100
	Vitacell LS 8430	Yeast Extract	3	Anti-stressing active
II.	Preservative, Parfum		q.s.
	Eumulgin L	PPG-1-PEG-9 Lauryl Glycol Ether	q.s.	Solubilizer
III.	Menthol-Primasponge-Small Size	Encapsulated Menthol	0,5	Encapsulated cooling agent
	pH: 5,5
	Viscosity (mPa*s) Brookfield RTV spindle TB 20ºC, 10 rpm : 12000

Preparation
Add the water slowly on the Hispagel 200 while stirring with low speed till it is a clear homogeneous swelling (Phase I). Add Phase II under low speed stirring. Mix Phase III and add to the former mixture. Finally add the Menthol-Primasponge and adjust the pH.

Hair styling gels

Hair styling gels can be easily obtained with film-forming polymers. Apart from its ease of use, Hispagel is compatible with ethanol and does not leave dandruff-like particles in the hair as it does not dry. Furthermore, gels made with Hispagel 200 have good spraying properties.

Creams and lotions

Hispagel can be used as a thickener and stabilizer for all kinds of O/W emulsions. It is very suitable for cold processing since it is only required to add the oil phase to the mixture of water and Hispagel while stirring.

For warm processing, it is possible to incorporate Hispagel either at high temperature (up to 80º C) or at room temperature, when the emulsion is already formed.

Further examples of formulations for a light body milk (cold preparation) and an oil-in-water soft cream are given in Tables 4 and 5.

Table 4: Light Body Milk (cold preparation)

Phase	Component	INCI	%	Function
I.	Eumulgin VL75	Lauryl Glucoside (and) Polyglyceryl-2 Dipolyhydroxystearate (and) Glycerin	4	O/W Emulsifier
	Cetiol J 600	Oleyl Erucate	1	Emollient
	Cetiol OE	Dicaprylyl Ether	2	Emollient
	Fitoderm	Squalane	2	Emollient
	Myritol 312	Caprylic/Capric Triglyceride	2	Emollient
	Dow Corning 200	Dimethicone	0,5	Emollient
	Water, de-ionized	Aqua	9,5
II.	Water, de-ionized	Aqua	ad 100
	Hispagel 200	Glycerin (and) Glyceryl Polyacrylate	18	Thickener, moisturizer
III.	Preservative, Parfum		q.s.
	pH: 5 — 5,5
	Viscosity (mPa*s) Brookfield RTV spindle TB 20º C, 10 rpm : 6.000

Preparation
1. Mix phase II adding the water bit by bit slowly in the Hispagel® 200 while stirring with slow speed 2. Mix phase I while stirring (5 min.) and add to phase II bit by bit 3. Add phase III and adjust the pH value if necessary.

Table 5: O/W Soft Cream

Phase	Component	INCI	%	Function
I.	Emulgade SE-PF	Glyceryl Stearate (and) Ceteareth-20 (and) Ceteareth-12 (and) Cetearyl Alcohol (and) Cetyl Palmitate	6	O/W Emulsion base, self-emulsifying
	Lanette O	Cetearyl Alcohol	1	Consistency giving factor
	Cutina MD	Glyceryl Stearate	2	Consistency giving factor
	Cetiol MM	Myristyl Myristate	2	Emollient
	Cetiol J600	Oleyl Erucate	2	Emollient
		Mineral Oil	8	Emollient
	Copherol 1250	Tocopheryl Acetate	0,5	Active Agent
II.	Water, de-ionized	Aqua	ad 100
III.	Hispagel 200	Glycerin (and) Glyceryl Polyacrylate	18	Thickener, moisturizer
IV.	Preservative, Parfum		q.s.
	pH: 5 — 5,5
	Viscosity (mPa*s) Brookfield RTV spindle TB 20º C, 10 rpm : 150.000

Preparation:
Heat phase I to 80ºC. Heat phase II to 80ºC and add to phase I while stirring. Allow the emulsion to cool in such a way that it remains in continual motion. Avoid incorporation of air. If necessary homogenize with a suitable dispersion unit (e.g. Ultra Turrax) approx. 55ºC. Add phase III and stir until complete homogeneous swelling. Add phase IV and adjust pH.

References:

1, 2, 3: Hispagel 200, Hispagel L, Primasphere and Primasponge are registered trademarks of Cognis Deutschland GmbH & Co KG.
* Hispagel 200, Hispagel L: INCI = glycerin (and) glyceryl polyacrylate

Contact address:

Cognis Iberia S.L. Pg.
Industrial San Vicente s/n 08755
Castellbisbal (Barcelona)
Spain

Phone (+34) 937 730 105
FAX (+34) 937 730 180
E-mail: Marta.Torres@Cognis.es - Technical Application Cosmetics or
Francesco.Fabra@Cognis.es

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June 2002