Study of cosmetic applications with unmodified cellulose nanofiber as novel gel type ingredient
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Presented by: Atsuko Ota
Introduction
Cellulose has been getting well known, since this material can be the best alternative of microplastics in all industrial field, especially in cosmetics field because of its biodegradability with OECD 301F and ASTM 6691D. Particularly, Cellulose Nano Fiber (CNF) is utilized as the reinforced material. In the application for cosmetics, CNF can be dispersed in water with very low concentration (under 1wt%) and this dispersion shows viscous properties, so that this material will be utilized as a thickener for cosmetics field.
Conventionally, in order to obtain CNF having diameters of single-nano size, we must modify cellulose molecules with carboxylic and/or phosphoric groups. However, we have developed the novel process to obtain unmodified single-nano sized CNF (RCNF). The RCNF shows excellent transparency in the dispersion in water. In comparison, the dispersion in water of conventional unmodified CNF becomes clouded. The dispersion using RCNF shows higher viscosity and better thixotropic property than that using conventional unmodified CNF. In this study, the properties of cosmetic formulations using RCNF were compared to those using Carbopol or xanthan gum. And we have found two very properties using RCNF as an ingredient in cosmetics.
1. The water dispersion with polyol gives gel film.
2. The water dispersion will be mixed and make emulsion with oil (squalene) without any emulsifier.
Experiments
We analyzed the rheological behaviors depending on shear rate for each concentration of water dispersions using rotating viscometer. We have made dried film with various concentration of 1,3-buthilene glycol (BG) and evaluated the properties of the film after drying for 18 hours at 50℃. We have made the evaluation of the stability of the emulsions, which are consisted of the water dispersion of RCNF with the various concentration of squalene without any surfactants. We have also made the evaluation of the emulsions under existing salts and various pH range. We have tried to make new formulations using this technique, namely gel type cosmetic formulations with UV absorbing silica treated TiO2, and made the evaluation of SPF values.
Results
1. Rheological properties
The viscosity of the water dispersion with RCNF shows relatively high under 1 wt% concentration, which is higher than that of the dispersion of Xanthan gum and lower than that of Carbopol. The viscosity will be affected by salt, such as NaCl, and pH same as the case of Carbopol. The dependence of the thixotropic property of the dispersion of RCNF is higher than that of conventional unmodified CNF,
2. Gel Film property
When 0.5 wt% of the water dispersion on RCNF is dried for 18 hours at 50℃, film is obtained. However, the film is very brittle. On the other hand, by adding of BG in this water dispersion, the dried film ends up jelly type. Jelly property will increase with the concentration of BG.
3. Emulsion with squalene
The composition of weight ratio of 24/56/20 (0.5 wt% of the water dispersion of RCNF/deionized water/squalene), is the best for the stable O/W emulsion without any surfactants. For Carbopol, we could make the same emulsion as the case of RCNF, however, we could not obtain the stable emulsion for Xanthan gum. The emulsions of RCNF are stable for the pH range 5-11. In comparison with the case of Carbopol, the stable range is 7-11. However, in addition of NaCl, the stability of the emulsion was getting less.
4. Possibility for new formulation
Silica treated TiO2 shows very good dispersibility in the water dispersion of RCNF and show very good SPF performance compared with the case of the conventional unmodified CNF.
Conclusion
In conclusion, the novel RCNF will be very lucrative ingredient for cosmetics, especially gel type cosmetics such as skin care and make-up, and as a biodegradable ingredient.
Cellulose has been getting well known, since this material can be the best alternative of microplastics in all industrial field, especially in cosmetics field because of its biodegradability with OECD 301F and ASTM 6691D. Particularly, Cellulose Nano Fiber (CNF) is utilized as the reinforced material. In the application for cosmetics, CNF can be dispersed in water with very low concentration (under 1wt%) and this dispersion shows viscous properties, so that this material will be utilized as a thickener for cosmetics field.
Conventionally, in order to obtain CNF having diameters of single-nano size, we must modify cellulose molecules with carboxylic and/or phosphoric groups. However, we have developed the novel process to obtain unmodified single-nano sized CNF (RCNF). The RCNF shows excellent transparency in the dispersion in water. In comparison, the dispersion in water of conventional unmodified CNF becomes clouded. The dispersion using RCNF shows higher viscosity and better thixotropic property than that using conventional unmodified CNF. In this study, the properties of cosmetic formulations using RCNF were compared to those using Carbopol or xanthan gum. And we have found two very properties using RCNF as an ingredient in cosmetics.
1. The water dispersion with polyol gives gel film.
2. The water dispersion will be mixed and make emulsion with oil (squalene) without any emulsifier.
Experiments
We analyzed the rheological behaviors depending on shear rate for each concentration of water dispersions using rotating viscometer. We have made dried film with various concentration of 1,3-buthilene glycol (BG) and evaluated the properties of the film after drying for 18 hours at 50℃. We have made the evaluation of the stability of the emulsions, which are consisted of the water dispersion of RCNF with the various concentration of squalene without any surfactants. We have also made the evaluation of the emulsions under existing salts and various pH range. We have tried to make new formulations using this technique, namely gel type cosmetic formulations with UV absorbing silica treated TiO2, and made the evaluation of SPF values.
Results
1. Rheological properties
The viscosity of the water dispersion with RCNF shows relatively high under 1 wt% concentration, which is higher than that of the dispersion of Xanthan gum and lower than that of Carbopol. The viscosity will be affected by salt, such as NaCl, and pH same as the case of Carbopol. The dependence of the thixotropic property of the dispersion of RCNF is higher than that of conventional unmodified CNF,
2. Gel Film property
When 0.5 wt% of the water dispersion on RCNF is dried for 18 hours at 50℃, film is obtained. However, the film is very brittle. On the other hand, by adding of BG in this water dispersion, the dried film ends up jelly type. Jelly property will increase with the concentration of BG.
3. Emulsion with squalene
The composition of weight ratio of 24/56/20 (0.5 wt% of the water dispersion of RCNF/deionized water/squalene), is the best for the stable O/W emulsion without any surfactants. For Carbopol, we could make the same emulsion as the case of RCNF, however, we could not obtain the stable emulsion for Xanthan gum. The emulsions of RCNF are stable for the pH range 5-11. In comparison with the case of Carbopol, the stable range is 7-11. However, in addition of NaCl, the stability of the emulsion was getting less.
4. Possibility for new formulation
Silica treated TiO2 shows very good dispersibility in the water dispersion of RCNF and show very good SPF performance compared with the case of the conventional unmodified CNF.
Conclusion
In conclusion, the novel RCNF will be very lucrative ingredient for cosmetics, especially gel type cosmetics such as skin care and make-up, and as a biodegradable ingredient.