7-2011

English EditionInternational Journal for Applied Science

• Personal Care • Detergents • Specialties

A. Howe, D. Adkins, M. Soldato, B. Jha, O. Springer

Phenoxyethyl Caprylate –A New Polar Emollient for

Organic UV Filters

38 SOFW-Journal | 137 | 7-2011

COSMETICSPHENOXYETHYL CAPRYLATE

A. Howe, D. Adkins, M. Soldato, B. Jha, O. Springer*

Phenoxyethyl Caprylate –A New Polar Emollient for Organic UV Filters

� Introduction

Sunscreen formulators are always tryingto improve/boost the SPF response oftheir systems. Key to this goal is the useof organic filters such as Butyl Methoxy-dibenzoylmethane which absorbs the ul-traviolet light A (UVA) better than mostother organic sunscreen technologies.This material along with other UVA fil-ters needs to be solubilized into the oilphase of the emulsion and needs to re-main soluble over the shelf life of theproduct. In addition to their role as sol-ubilizers, emollients also constitute amajor portion of the oil phase of per-sonal care formulation and largely de-termine its properties. Especially in thesun care formulations of today, it is a ne-cessity that the emollients are multi-functional: i.e. by delivering a pleasantskin feel while at the same time display-ing excellent solublization and disper-sion properties. These attributes play animportant role during new product de-velopment in this application area, thusthere is a need to find new highly effi-cient emollients for use in sunscreen ap-plications that will meet these require-ments. Evonik Goldschmidt has devel-oped such a product, a new photostableemollient with superb aesthetics and ex-cellent solubility properties for organicUV filters that can additionally providean SPF boosting effect in sun care for-mulations.

� Comparing Solubilizing Capacity

In Fig. 1 the global regional limits arelisted for several commonly used sun fil-

ters. Typically, polar emollients are uti-lized to solvate these structures withC12-15 Alkyl Benzoate being amongthose that are used most frequently. Ac-cordingly, this material was used as ourbenchmark to identify new emollientswith enhanced properties.

Phenoxyethyl Caprylate is the esterifi -cation product of Phenoxyethanol andCaprylic Acid and is over 50% vegetablebased (Fig. 2). This new emollient is high-ly polar, and improves the solubility oflipophilic crystalline structures such asBenzophenone-3, Bis-Ethylhexyloxyphe-nol Methoxyphenyl Triazine, Butyl Meth-oxydibenzoylmethane and Ethylhexyl Tria-zone in sun care formulations. In Fig. 3Phenoxyethyl Caprylate was comparedagainst the industry standard, C12-15Alkyl Benzoate for its ability to solubilizeorganic sun filters. As a result of the test-ing, Phenoxyethyl Caprylate was shownto be superior to C12-15 Alkyl Benzoatein this category.

SPF BoostingThe addition of key ingredients, such asemollients can improve the efficiency ofthe sun protection factor. If proper sol-ubility of the UV filters are maintainedan SPF boosting effect of the sunscreen

Filter substances chosen for testing

BMDM (UV-A filter)

• INCI: Butyl Methoxy-dibenzoylmethane

• USAN: Avobenzone• US: max. 3%; EU: max. 10%

BP3 (UV-B filter)

• INCI: Benzophenone-3• USAN: Oxybenzone• US: max. 6%; EU: max. 10%

Fig. 1 Good organic UV filter solubility

BEMT (UV-A filter)

• INCI: Bis-EthylhexyloxyphenolMethoxyphenyl Triazine

• USAN: Bemotrizinol• US: not allowed; EU: max. 10%

EHT (UV-B filter)

• INCI: Ethylhexyl Triazone• USAN: Octyl Triazone• US: not allowed; EU: max. 5%

Fig. 2 Molecular structure, names andregistry numbers

INCI name: Phenoxyethyl Caprylate

CAS No.: 23511-73-1

EINECS: 607-240-0

SOFW-Journal | 137 | 7-2011 39

COSMETICSPHENOXYETHYL CAPRYLATE

system can be achieved. An in vivo SPFstudy was performed with two differ-ent formulations comparing Phenoxy-ethyl Caprylate with C12-15 Alkyl Ben-zoate, at AMA Laboratories, USA. Oneformula according to EU Colipa require-ment, and the other according to the USFDA requirement. The results showedthat an increase in SPF can be seen withboth regional requirements (Fig. 4). Theeffect is more pronounced with the USbased formulation than the EU formula-tion (Formulations 1 and 2).

Sensory AssessmentIt is desirable to have emollients con-tribute to a light and pleasant skin feel.The two previous sunscreen systems thatwere tested for increased SPF responsewere also assessed for aesthetics by atrained sensory panel. The results showedthat Phenoxyethyl Caprylate was per-ceived to impart a less-oily skin feelcompared to C12-15 Alkyl Benzoate insun care formulations (Fig. 5).

DensityPhenoxyethyl Caprylate exhibits a den-sity which is very similar to that of water. Hence, oil-in-water emulsionswhich are low in viscosity will show a reduced tendency towards phase sepa-ration with the incorporation of Phe-noxyethyl Caprylate. This in turn trans-lates to an improved stability profile ofthe emulsion (Fig. 6).

Pigment WettingA simple method with which to comparethe wetting efficiency of liquids is tomeasure the viscosity of the dispersionthat is formed by the wetting agent andthe pigment. As the capacity of a liquidto wet pigment increases, the viscosity ofthe dispersion decreases. As illustrated inFig. 7, the results show that due to Phe-noxyethyl Caprylate’s higher polarity, it is more effective at wetting out hy-drophilic pigments (like MICA, ZnO) thanC12-15 Alkyl Benzoate.

SustainabilityPhenoxyethyl Caprylate is based on a

Fig. 3 Comparing Organic UV filter solubility

Fig. 4 In vivo SPF test

A TEGIN ® M Pellets (Glyceryl Stearate) 2.00%C12-15 Alkyl Benzoate* or TEGOSOFT ® XC** 8.00%TEGO® Alkanol 1618 (Cetearyl Alcohol) 1.00%Butyl Methoxydibenzoylmethane 5.00%Octocrylene 7.00%Tocopheryl Acetate 0.50%Ethylhexyl Methoxycinnamate 3.20%TEGO® Sun T 805 (Titanium Dioxide; Trimethoxycaprylylsilane) 5.00%

B Xanthan Gum 0.30%TEGO® Care CG 90 (Cetearyl Glucoside) 1.00%Glycerin 2.00%Water 63.80%

Z Preservative (Euxyl K 300) 1.00%Perfume 0.20%

* SPF (in vitro) (Optometrics): 28 SPF (in vivo): 52** SPF (in vitro) (Optometrics): 36 SPF (in vivo): 56

Formulation 1 for in vivo SPF test

vegetable fatty acid (Caprylic acid), mak-ing it 54% vegetal or renewable. C12-15 Alkyl Benzoate is completely based onsynthetic material and can not offer thisadditional benefit.

� Application

Phenoxyethyl Caprylate can be utilizedfrom 1-10 % in both oil-in-water andwater-in-oil emulsions. Possible applica-tions include:

• Sun care• Skin care creams and lotions• Spray emulsions• AP/deodorants• Color cosmetics

� Summary

Phenoxyethyl Caprylate is a highly polarester emollient of Phenoxyethanol andCaprylic Acid (over 50% based on veg-etable raw materials). This new emollient

40 SOFW-Journal | 137 | 7-2011

COSMETICSPHENOXYETHYL CAPRYLATE

Fig. 5 Sensorial Properties in light O/W Sun Care Lotion SPF 30 UVA Phenoxyethyl Caprylate vs. C12-15 Alkyl Benzoate

A TEGO® Care 165 (Glyceryl Stearate; PEG-100 Stearate) 3.50%TEGO® SMO 80 V (Polysorbate 80) 0.30%TEGIN® M Pellets (Glyceryl Stearate) 2.00%TEGO® Alkanol 1618 (Cetearyl Alcohol) 1.00%C12-15 Alkyl Benzoate* or TEGOSOFT® XC** 8.00%Octocrylene 7.00%Benzophenone-3 5.00%Menthyl Anthranilate 4.00%Ethylhexyl Methoxycinnamate 3.00%Polyamide-4 (Sylvaclear WF 1500 V , Arizona Chemical) 2.00%

B TEGO® Sun T 8052 (1) (Titanium Dioxide; Trimethoxycaprylylsilane) 4.00%Xanthan Gum 0.20%

C LACTIL® (Sodium Lactate; Sodium PCA; Glycine; Fructose; Urea; Niacinamide; Inositol; Sodium Benzoate; Lactic Acid) 1.00%Allantoin 0.10%Glycerin 2.00%Water 55.90%

Z Preservative q.s.Perfume q.s.

(1) TEGO® Sun T 805 G for USA

* SPF (in vitro) (Optometrics): 72 SPF (in vivo): 75** SPF (in vitro) (Optometrics): 86 SPF (in vivo): 81

Formulation 2 for in vivo SPF test

has outstanding solubility properties andprovides an SPF boosting effect in bothUS and European sun care formulations.Due to the branching of the Phenoxy-ethyl Caprylate molecule this polar emol-

lient has a lower viscosity than C12-15Alkyl Benzoate and lends a non-oily andnon-tacky skin feel to emulsions. Phe-noxyethyl Caprylate’s water-like densityalso improves the stability profile of low

viscosity oil-in-water emulsions. Finally,due in part to its high polarity, Phe-noxyethyl Caprylate is extremely effi-cient at wetting out hydrophilic parti-cles. All of these factors together com-bine to make Phenoxyethyl Caprylatethe perfect choice of emollient for mod-ern high performance sun care products.

* Authors’ address:Anna Howe, Dana Adkins

Maria Soldato, Dr. Brajesh JhaDr. Oliver Springer

Evonik Goldschmidt Evonik Goldschmidt

710 South 6th AvenueHopewell, Virginia

USAEmail: anna.howe@evonik.com

�

SOFW-Journal | 137 | 7-2011 41

COSMETICSPHENOXYETHYL CAPRYLATE

Fig. 6 Easy access to stable low-viscous O/W emulsions

Fig. 3 Comparing Organic UV filter solubility