SPF booster for sunscreen composition

Abstract

The present invention relates to a cosmetic composition (e.g. sunscreen composition), and to a method for making the cosmetic composition.

Description

[0001] SPF BOOSTER FOR SUNSCREEN COMPOSITION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a cosmetic composition (e.g. sunscreen composition), a package containing the cosmetic composition and to a method for making the cosmetic composition.

[0004] BACKGROUND OF THE INVENTION

[0005] The ultraviolet (UV) radiation from the sun or artificial sources are known to be harmful to human. For example, it causes sunburn, erythema, loss of skin elasticity, premature aging of the skin, and even skin cancer. To protect skin from such harmful effects of UV radiation, numerous sunscreens are developed and used. However, it is evident that the active ingredients in sunscreen, those are inorganic and organic UV filters, have unfavorable safety impacts on human and the environment. For example, the UV absorption of both UV filters increases their photoactivity, resulting in the generation of harmful radicals; a range of organic UV filters have been found in several aquatic organisms and also may cause bleaching of coral reefs in the ocean. Therefore, minimizing the quantities of UV filters used in sunscreen while maintaining high sun protection efficacy is a key challenge.

[0006] Introducing a sun protection factor booster (SPF booster) in sunscreen formulations has been considered as an effective strategy to reduce the proportion of UV filter but still offer a high level of skin protection. SPF boosters are not active absorbers but increase SPF value through light scattering. Significant effort has been focused on the development of SPF boosters from natural sources, such as green coffee oil and spruce bark stilbenes, to modification of natural biomass, such as lignin-based substances (e.g. lignosulfonate). Another type of SPF booster is based on the synthetic polymer-based materials, such as polydopamine and styrene / acrylates copolymer. Although both natural sources and polymers as SPF booster are biocompatible, they usually contain organic components with UV absorption in the range of UVA / UVB, which might lead to a poor photostability and require a restricted cosmetic audit process to a legal and safety point of view.

[0007] There are other attempts to use an inorganic SPF booster, such as TiO2, ZnO and silica. The developed inorganic boosters typically have the photocatalytic activity, which would result in the photodegradation of organic UV filter. Apart from that, TiO2and ZnO have been authorized as UV filters. So, their use as SPF booster in sunscreen is restricted and limited according to relevant policies. Therefore, developing a biocompatible, safe and effective inorganic SPF booster is in great demand for sunscreen.

[0008] SUMMARY OF THE INVENTION

[0009] According to a first aspect, the present invention provides a cosmetic composition comprising: an UV filter and a sun protection factor booster (SPF booster); wherein the SPF booster comprises a layered double hydroxide (LDH); and the layered double hydroxide has an average particle diameter in a range of 15 - 450 nm.

[0010] According to a further aspect, the present invention provides a package containing the cosmetic composition as herein defined.

[0011] According to a further aspect, the present invention provides a process for the preparation of the cosmetic composition as herein defined, comprising a step of mixing the UV filter and SPF booster.

[0012] DEFINITIONS

[0013] Hereinafter, various embodiments of the present disclosure will be described in detail so that those ordinarily skilled in the art to which the present disclosure pertains can easily carry out the present disclosure. However, these are only examples given for illustrative purposes, and the scope of the present disclosure is not intended to be limited to the following contents.

[0014] Unless otherwise restricted, a detailed description defining or specifying the elements may be applied to all inventions, and is not limited to descriptions of particular inventions. That is, the present disclosure also refers to combinations of the embodiments even if they are disclosed separately.

[0015] Additionally, unless explicitly stated otherwise, a singular form includes a plural form throughout the detailed description and the appended claims.

[0016] As used herein, when a part "includes" a certain component, it means that it may further include other components, not excluding other components unless specifically otherwise stated. However, unless explicitly stated otherwise, “comprising” or “including” or the like includes “essentially comprising" and “consisting of’.

[0017] The term “essentially comprises” as used herein has the meaning of “comprising at least 70 %”, preferably of “comprising at least 80 %”, most preferred of “comprising at least 90 %”. If reference is made to the amount of a constituent in a mixture of material, % is wt%, relative to the total weight of the respective mixture. For example, a SPF booster essentially comprising LDH comprises the LDH in an amount of at least 70 wt% with respect to the total weight of the SPF booster.

[0018] Additionally, the terms "about" and "substantially" as used herein are used in the sense of at, or nearly at, when given the manufacturing and material tolerances inherent in the stated circumstances, and are used to prevent the unscrupulous infringer from unfairly taking advantage of the present disclosure where exact or absolute figures are stated as an aid to understanding the present disclosure.

[0019] As used herein, "A and / or B" means "A and B, or A or B".

[0020] As used herein, the term “UV filter” refers to a compound or material for use in a photo-protector formulation wherein the UV filter interferes directly with the incident ultraviolet radiation through absorption, reflection or dispersion of energy.

[0021] As used herein, the term “Sun protection factor booster” or “SPF booster” refers to a compound or material enabling to reduce the proportion of UV filter in a photo-protector formulation while maintaining or improving the high level of skin protection Preferably, the sun protection booster has one or more, preferably all of the following properties: (i) low UV radiation absorption; (ii) safe for both human use and the environment; (iii) compatible with a wide variation of sunscreen formulations. The term “SPF booster and UV booster term may be used interchangeably.

[0022] As used herein, the term “wt%” is based on the total weight of the composition, unless otherwise specified.

[0023] As used herein, the term “interlayer water” and “interlayer solvent” refers to water and solvent, respectively, which is located between (but preferably not absorbed to the surface of) metal double hydroxide layers in a LDH. As used herein, the term “surface-bound water” and “surface-bound solvent” refers to water and solvent, respectively, which is located at or absorbed on the surface of a metal double hydroxide layer.

[0024] DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention provides a cosmetic composition comprising: a UV filter and a sun protection factor booster (SPF booster) wherein the SPF booster comprises, essentially comprises or consists of a layered double hydroxide (LDH) having an average particle diameter in a range of 15 to 450 nm.

[0026] The present invention advantageously provides a cosmetic composition that can use less UV filter while maintaining high sun protection efficiency. Additionally, the cosmetic composition comprising the UV filter and the sun protection factor booster is thermal and UV stable, has low photocatalytic activity, is biocompatible and comprises non-toxic inorganic platelets. These properties make the cosmetic compositions of the present invention particularly suitable for applying on target area (e.g. skin) in order to protect it from harmful effects of UV radiation, and less harm to human and environment.

[0027] In one embodiment, the LDH has an average particle diameter of 60 or more, 100 or more, 150 or more, 200 or more, or 225 or more. In one embodiment, the LDH has an average particle diameter of 450 nm or less, 400 nm or less, 350 nm or less, or 335 nm or less.

[0028] In one embodiment, the LDH has an average particle diameter in a range of 60 - 450 nm, preferably 100 - 450 nm, more preferably 150 - 450 nm, even more preferably 200 - 450 nm, yet more preferably 200 - 400 nm, still more preferably 225 - 350 nm, most preferably more preferably 225 - 335 nm. Another preferred average particle diameter of LDH is in a range of 150 - 375 nm, preferably 175 - 350 nm, more preferably 200 - 325 nm, even more preferably 225 - 300 nm, yet more preferably 250 - 300 nm, still more preferably 275 - 300 nm, most preferably 280 - 295 nm. In this regard, the diameter of a particle, that is, an LDH particle, may refer to the largest distance between two (opposed) surfaces of the particle.

[0029] In one embodiment, the LDH has in platelet shape. Preferably, the LDH may have a 2D nanoplatelet shape with a narrow platelet diameter distributions. The LDH may be prepared by 1) creating instantaneous nucleation of the LDH nanoplatelets by rapid mixing a metal precursors with a mixture of anionic solution and alkaline solution, 2) dispersing this as-formed wet solid in deionized water (DI water) for subsequent hydrothermal treatment, and 3) hydrothermal temperature treating at temperature from 25 to 350°C, such as from 25 to 200°C, preferably from 100°C to 200°C, most preferred from 150°C to 200°C.

[0030] In further preferred cosmetic composition of the present invention, the LDH in platelet shape and / or in 2D nanoplatelet shape, is homogeneously distributed (thoroughly dispersed) in the cosmetic composition. More preferably, the LDH platelet and / or 2D LDH nanoplatelet is uniformly dispersed and / or distributed throughout the cosmetic composition.

[0031] In one embodiment, the cosmetic composition comprises 0.03 wt% or more, 0.05 wt% or more, or 0.1 wt% or more of the LDH based on total weight of the cosmetic composition.

[0032] In one embodiment, the cosmetic composition comprises 10 wt% or less, 7 wt% or less, 5 wt% or less, 3 wt% or less, 2 wt% or less, lwt% or less, or 0.6wt% or less, of LDH based on total weight of the cosmetic composition.

[0033] In one embodiment, the cosmetic composition comprises 0.03 - 10 wt%, preferably 0.1 - 10 wt%, more preferably 0.1 - 7 wt%, even more preferably 0.1 - 5 wt%, yet more preferably 0.1 - 3 wt%, still more preferably 0.1 - 2 wt%, still more preferably 0.1 - lwt%, most preferably 0.1 - 0.6wt%, of the LDH based on total weight of the cosmetic composition. Another preferably, the cosmetic composition comprises 0.2 - 15 wt%, preferably 0.2 - 10 wt%, more preferably 0.2 - 7 wt%, even more preferably 0.5 - 7 wt%, yet more preferably 1 - 7 wt%, most preferably 3 - 7 wt% of the LDH based on total weight of the cosmetic composition.

[0034] In one embodiment, the LDH comprises, essentially comprises or consists of: a) metal double hydroxide layers with a formula:

[0035] [MZ+7- M^+X(OH)2] (I) wherein M and M' are different from each other, and M and M’ are each is at least one metal cation,

[0036] Z = 2; y = 3 or 4 and

[0037] 0 < x < 1; b) an interlayer anion; c) optionally at least one selected form the group consisting of interlayer water; surface-bound water; interlayer solvent; and surface-bound solvent.

[0038] Preferably, in formula (I), M is Mg, Zn, Ca, or a mixture thereof.

[0039] Preferably, in formula (I), when y is 3, M' is Al, Ti, or a mixture thereof, or, when y is 4, M' is Ti.

[0040] Preferably, in formula (I), the interlayer anion is selected from at least one of halide, inorganic oxyanion, and anionic surfactants.

[0041] The interlayer anion in the LDH may be any appropriate anion, organic anion and / or inorganic anion, for example a halide anion (e.g., chloride, bromide), an inorganic oxyanion (e.g. XpOq(OH)rs; p = 1-5; q = 2-10; r = 0-4, s = 1-5; X = B, C, N, S, P: e.g. carbonate, bicarbonate, hydrogenphosphate, dihydrogenphosphate, nitrite, borate, nitrate, phosphate, sulphate), an anionic surfactant (such as sodium dodecyl sulfate, fatty acid salts or sodium stearate) or a mixture of two or more thereof.

[0042] The interlayer solvent and / or surface-bound solvent may be an organic solvent with a hydrogen bond donor or acceptor function, which is preferably, in any amount, miscible with water. Hydrogen bond donor groups may include R-OH, R-NH2, R2NH, whereas hydrogen bond acceptor groups may include ROR, R2C=O, RNO2, R2NO, R3N, ROH, RCF3 [R is hydrocarbyl group]. Exemplary organic solvents which may be the interlayer solvent and / or surface-bound solvent include ethyl acetate, acetone, acetonitrile, dimethylformamide, dimethylsulfoxide, dioxane, ethanol, m-cresol, o-cresol, p-cresol, methanol, n-propanol, isopropanol, n-butanol, sec-butanol, n-pentanol, n-hexanol, cyclohexanol, diethyl ether, diisopropyl ether, di-n-butyl ether, methyl tert-butyl ether (MTBE), tert-amyl methyl ether, cyclopentyl methyl ether, anisole, butyl carbitol acetate, cyclohexanone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl isoamyl ketone, methyl n-amyl ketone, isophorone, isobutyraldehyde, furfural, methyl formate, methyl acetate, isopropyl acetate, n- propyl acetate, isobutyl acetate, n-butyl acetate, n-amyl acetate, n-hexyl acetate, methyl amyl acetate, methoxypropyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, n-butyl propionate, n-pentyl propionate, triethylamine, 2-nitropropane, aniline, N,N-dimethylaniline, nitromethane, tetrahydrofurane, and mixtures of two or more thereof. Preferably, the interlayer solvent and / or the surface-bound solvent is ethanol or acetone.

[0043] Preferably, in formula (I), x is 0.1 - 0.9, more preferably 0.1 - 0.7, even more preferably 0.1 - 0.5, yet more preferably 0.1 - 0.33, still more preferably 0.25 - 0.33, such as about 0.33.

[0044] Preferably, the metal double hydroxide layers of the LDH have the formula [M / wherein (l-x)l x = 1.8-5, preferably 1.8-4, more preferably 2-4, even more preferably 2-3.

[0045] Particular preferably, the LDH comprises metal double hydroxide layers having the formula [Mg / AA1A(OH)2] wherein (1-x) / x = 1.8-5, preferably 1.8-4, more preferably 2-4, even more preferably 2-3. More preferably the LDH comprises metal double hydroxide layers having the formula [Mg / AA1A(OH)2] wherein (1-x) / x = 2-3 and the interlayer anion is carbonate.

[0046] More particular preferably, the LDH comprises metal double hydroxide layers [Mg0.66Alo.33(OH)2] Or [Mg0.67Alo.33(OH)2].

[0047] In preferred cosmetic compositions of the present invention, the LDH comprises metal double hydroxide layers [Mgo.67Alo.33(OH)2] and the interlayer anion is carbonate.

[0048] In more preferred cosmetic compositions of the present invention, the LDH is [(Mg0.67Alo.33(OH)2][C03]o.l65*wH20.

[0049] Preferably, the UV filter is selected from the group consisting of titanium dioxide, zinc oxide, kaolin, talc, calamine, benzophenone and derivatives thereof, dibenzoylmethane and derivatives thereof, anthranilate and derivatives thereof, benzylidene camphor and derivatives thereof, aminobenzoic acid and derivatives thereof, cinnamic acid and derivatives thereof, salicylate and derivatives thereof, benzimidazole and derivatives thereof, benzotriazole derivatives thereof, triazine / triazole derivatives, ascorbic acid, P-carotene, a- tocopherol, aspirin, indomethacin, corticosteroids, selenium, retinol, green tea polyphenol, and a mixture of two or more thereof.

[0050] The benzophenone and derivatives thereof include, without limitation, dioxybenzone (benzophenone- 8 (BP-8) or 2,2 '-dihydroxy-4-m ethoxy benzophenone), sulisobenzone (2- hydroxy-4-methoxybenzophenone-5-sulfonic acid), oxybenzone (2-hydroxy-4- methoxybenzophenone or benzophenone-3 (BP-3)), hexyl 2-[4-(diethylamino)-2- hydroxybenzoyl] benzoate, bis-(diethylaminohydroxybenzoyl benzoyl) piperazine (BDBP), benzoresorcinol, 2,2 ',4,4 '-tetrahydroxybenzophenone, 2,2 '-dihydroxy-4,4'- dimethoxybenzophenone, octabenzone, 4-isopropyldibenzoylmethane, butylmethoxydibenzoylmethane, etocrylene, and 4-isopropyl-dibenzoylmethane), or a mixture of two or more thereof.

[0051] The dibenzoylmethane and derivatives thereof include, without limitation, avobenzone (butyl methoxydibenzoylmethane), isopropyl dibenzoylmethane, or a mixture of two or more thereof.

[0052] The anthranilate and derivatives thereof include, without limitation, meradimate (menthyl anthranilate), o-aminobenzoates, methyl anthranilate, phenyl anthranilate, benzyl anthranilate, phenylethyl anthranilate, linalyl anthranilate, terpinyl anthranilate, ethyl- [bis(hydroxypropyl)] aminobenzoate, glyceryl aminobenzoate, a cyclohexenyl anthranilate ester, or a of two or more mixture thereof.

[0053] The benzylidene camphor and derivatives thereof include, without limitation, enzacamene (4-methylbenzylidene camphor, benzylidene camphor sulfonic acid, camphor benzalkonium methosulfate, ecamsule (terephthalylidene dicamphor sulfonic acid), polyacrylamidomethyl benzylidene camphor, or a mixture of two or more thereof.

[0054] The aminobenzoic acid and derivatives thereof include, without limitation, ethylhexyl dimethyl p-aminobenzoic acid, ethoxylated ethyl-4-aminobenzoate, Padimate O, or a mixture of two or more thereof.

[0055] The cinnamic acid and derivatives thereof include, without limitation, cinoxate (2- ethoxyethyl 4-methoxycinnamate), octinoxate (2-ethylhexyl 4-methoxycinnamate), octocrylene (2-ethylhexyl ester of 2-cyano-3,3-diphenylacrylic acid), amiloxate (isopentyl 4- methoxy cinnamate), or a mixture of two or more thereof.

[0056] The salicylate and derivatives thereof include, without limitation, homosalate (homomenthyl salicylate), octisalate (2-ethylhexyl salicylate), trolamine salicylate, or a mixture of two or more thereof.

[0057] The benzimidazole and benzotriazole derivatives thereof include, without limitation, ensulizole (2-phenylbenzimidazole-5-sulfonic acid), bisdisulizole disodium (disodium Phenyl dibenzimidazole tetrasulfonate), drometrizole trisiloxane, bisoctrizole (methylene bis- benzotriazolyl tetramethylbutylphenol), or a mixture of two or more thereof.

[0058] The triazine / triazole derivatives include, without limitation, silatriazole, ethylhexyl triazone (2,4,6-trianilino-(p-carbo-2'-ethylhexyl-r-oxy)-l,3,5-triazine), iscotrizinol (diethylhexyl butamido triazone), bemotrizinol or anisotriazine (bis-ethylhexyloxyphenol methoxyphenyl triazine), tris-biphenyl triazine (2,4,6-tri([l,l'-biphenyl]-4-yl)-l,3,5-triazine), phenylene bis-diphenyltriazine (3,3'-(l,4-phenylene)bis(5,6-diphenyl-l,2,4-triazine)), or a mixture of two or more thereof.

[0059] The cosmetic compositions of the present invention may further comprise a photostabilizer, an antioxidant, a moisturizer, an emulsifier, a dispersant, a film former, a thickener, a sensory enhancer, a vitamin, an oil control agent, an anti-aging active, a skin lightening agent, a tanning active, an antiperspirant active, an antimicrobial active, a preservative, a fragrance, a solvent, or a mixture of two or more thereof.

[0060] The cosmetic composition of the present invention may be a sunscreen composition, a skincare composition, a hair care composition, a skin-tanning composition, a cosmetic composition, a make-up composition, a lip balm, a skin facial peeling composition, a moisturizing composition, an anti-aging skincare composition or a mixture of two or more thereof.

[0061] The invention is further directed to a process for the preparation of the cosmetic composition according to the present invention, wherein the process comprises a step of mixing the UV filter and the SPF booster.

[0062] It will be appreciated that, although specific embodiments of the present invention have been described herein for the purposes of illustration, various modifications may be made without departing from the scope of the disclosure. Accordingly, the disclosure is not limited except as by the appended claims.

[0063] In the following section, further advantages and features of the present invention are illustrated by way of examples.

[0064] BRIEF DESCRIPTION OF THE FIGURES

[0065] Fig. 1 shows schematically four optical measurement modes, namely FS (forward scattering), BS (backward scattering), TS (total scattering) and STR (scattering transmittance reflectance) using an integrating sphere measurement system and the samples in a 1 cm quartz cuvette. These optical modes were used for determining the properties shown in Tables 5 and 6 were also used for determining UV absorbance as shown e.g. in Tables 1 to 3 and Figs. 3 to 5 according to Auv = 1 - STR.

[0066] Fig. 2 (a) shows XRD patterns for Mg2Al-LDH nanoplatelets having different average particle diameters; Fig. 2 (b-f) show TEM images for Mg2Al-LDH-25, Mg2Al-LDH-50, Mg2Al-LDH-100, Mg2Al-LDH-150 and Mg2Al-LDH-200, respectively, which have different average particle diameters. The insets are the particle diameter distributions using the TEM images.

[0067] Fig. 3 shows graphs of (a) UV absorbance of 0.1 wt% Mg2Al-LDH nanoplatelets in DI water. The inset images are the dispersion of 0.1 wt% Mg2Al-LDH in DI water; (b) UV absorbance of 0.1 wt% Mg2Al-LDH-150 in DI water, 0.0003 wt% Tinosorb®S Lite Aqua in water, and a mixture of 0.0003 wt% Tinosorb®S Lite Aqua and 0.1 wt% Mg2Al-LDH nanoplatelets in DI water; (c-d) the boosting effect of Mg2Al-LDHs particle diameter on Tinosorb®S Lite Aqua and its summary of the absorbance at 340 nm. Error bar represents standard error from the repeated experiments.

[0068] Fig. 4 shows graphs showing the boosting effect of 0.1 wt% Mg2Al-LDH-150 on (a) Uvinul® A Plus Granular; (b) Uvinul® T 150.

[0069] Fig. 5 (a-b) shows graphs showing UV absorbance of the mixtures with various %loading of Mg2Al-LDH-150 and 0.0003 wt% Tinosorb S Lite Aqua in DI water and its summary of the absorbance at 340 nm.

[0070] Fig. 6 shows graphs showing SPF values of a commercial sunscreen containing various %loading of Mg2Al-LDH-150.

[0071] Fig. 7 shows graphs showing (a) the stability of the UV absorbance of a mixture of commercial sunscreen and Mg2Al-LDH-150 nanoplatelets after 240 h in the dark; (b) the photostability of a mixture of commercial sunscreen and Mg2Al-LDH-150 nanoplatelets after 2-h UV radiation. Inset image is UV absorbance at 360 nm with and without UV radiation. Error bar represents standard error from the repeated experiments.

[0072] Fig. 8 Graphs showing (a) %light scattering at 290-400 nm of 0.1 wt% Mg2Al- LDHs in DI water; (b) %total scattering (TS) and %side scattering (SS) of 0. 1 wt% Mg2Al- LDHs in DI water; UV absorbance of a mixture of 0.0003 wt% Tinosorb®S Lite Aqua and 0.1 wt% Mg2Al-LDHs in DI water. Error bar represents standard error from the repeated experiments.

[0073] Fig. 9 Graphs showing (a) %light scattering at 290-400 nm of various %loading of Mg2Al-LDH-150 in DI water; (b) %total scattering (TS) and %side scattering (SS) of various %loading of Mg2Al-LDH-150 in DI water; UV absorbance of a mixture of 0.0003 wt% Tinosorb®S Lite Aqua and various %loading of Mg2Al-LDH-150 in DI water. Error bar represents standard error from the repeated experiments.

[0074] The abbreviations used in the below examples and tables have the following meanings Mg2Al-CO3 LDH and Mg2Al-LDH : [(Mgo.67Alo.33(OH)2][C03]o.i65*«H20 wherein n > 0

[0075] EXAMPLES

[0076] Materials and methods

[0077] Materials

[0078] Sodium hydroxide (NaOH), sodium carbonate (ISfeCCL), magnesium nitrate hexahydrate (Mg(NOs)2 6H2O), and aluminium nitrate nonahydrate (Al(NOs)3 9H2O) were purchased from Sigma-Aldrich. The UV filters, including Tinosorb®S Lite Aqua (Bisethylhexyloxyphenol methoxyphenyl triazine (and) acrylates / C12-22 alkyl methacrylate copolymer; UVA+UVB filter), Uvinul® T 150 (2,4,6-trianilino-(p-carbo-2'-ethylhexyl-l'- oxy)-l,3,5-triazin; oil soluble UVB filter) and Uvinul® A Plus Granular (2-(4-(diethylamino)- 2-hydroxybenzoyl] -benzoic acid hexylester; UVA-I filter) were obtained from BASF. The commercial sunscreens (NIVEA SUN protect & moisture lotion SPF 20 and NIVEA SUN protect & moisture lotion SPF 15) were purchased from NIVEA. All chemicals and materials were used without purification.

[0079] Synthesis of MgiAl-CQj LDH nanoplatelet

[0080] The metal precursor solution of 8.552 g Mg(NC>3)2 6H2O (33.4 mmol) and 6.25 g A1(NO3)3’9H2O (16.67 mmol) dissolved in 50 mL of DI water were added quickly into an aqueous mixing solution of 3.5298 g Na2COs (33.4 mmol) and 4 g NaOH (100 mmol) dissolved in 200 mL of DI water under a 1000 rpm stirring at room temperature. The suspension was continuously stirred for 30 mins at room temperature. The mixture was divided into 5 tubes for centrifugation and then washed by DI water for three times. Following redispersion the solid product of each tube in 50 mL DI water, and aging at 25, 50, 100, 150 and 200 °C for 18 h, respectively. The obtained Mg2Al-LDHs were denoted as Mg2Al-LDH-25, Mg2Al-LDH-50, Mg2Al-LDH-100, Mg2Al-LDH-150 and Mg2Al-LDH-200, respectively. The solid powder of Mg2Al-LDHs, obtained by centrifuging Mg2Al-LDHs then drying at 30°C in vacuum oven overnight. Characterization and measurement methods

[0081] Powder X-ray diffraction (XRD)

[0082] Powder X-ray diffraction (XRD) measurements were recorded on Bruker D8 diffractometer (40 kV and 30 mA) with Cu Karadiation ( i = 1.544 A and Xz = 1.541 A). Samples were mounted on PMMA (polymethyl methacrylate) sample holders.

[0083] Transmission electron microscopy (TEM)

[0084] Transmission electron microscopy (TEM) images were gained by a JEOL 2100 microscope with an accelerating voltage of 200 kV using a single tilt specimen holder at DCCEM within the Department of Materials, University of Oxford. Samples were dispersed in ethanol with sonication and then casted onto copper grids.

[0085] The particle diameter distribution of sample was obtained by randomly measuring approximately 150 nanoparticles by TEM, following the calculation of their average particle diameter (d) according to the equation of d = iidi / di and the standard deviation, nt is the number of particle that has diameter di and di is the diameter of particle.

[0086] Optical measurements

[0087] Optical measurement was conducted by using the UV-Vis-NIR spectrophotometer (PerkinElmer lambda 1050+). Both UV / vis scattering and absorption were measured by using a 150 mm diameter integrating sphere on suspension samples well dispersed in 1 cm quartz cuvettes (Fig. 1).

[0088] To investigate UV / vis scattering properties, different modes for measurement were used. FS (forward scattering) measures all the scattered light propagates to the forward direction, the cuvette is positioned in the front of the integrating sphere. BS (backward scattering) counts for all the scattered light propagating to the backward direction, the cuvette is attached to the backside of the integrating sphere. TS (total scattering) is all the scattered light in all directions, and the cuvette in put inside the integrating sphere. Side scattering (SS) can be calculated as:

[0089] SS = TS - FS - BS

[0090] To get the portion of the absorption, we need to know all the light that is scattered, directly reflected and directly transmitted. In the STR (Scattering Transmittance Reflectance) mode, all the light that scattered in all directions, directly transmitted and directly reflected are all collected by the integrating sphere, therefore, the UV absorption (Auv) of all suspension samples can be calculated as:

[0091] Auv = 1 - STR

[0092] The boosting effect was conducted by comparing the UV absorption (Auv) with and without adding SPF booster to the UV absorbers (denoted as Auv-w / booster and Auv -0 / w booster, respectively). Both commercial, skin contact-approved UV filters and commercial sunscreens were used as UV absorbers. For Tinosorb®S Lite Aqua, its UV absorption (Auv) was measured to get the solid content dependent UV absorption by using DI water as diluting agent. The boosting effect (Eboosting) was calculated as followings:

[0093] Eboosting AuV-w / booster / AuV-O / w booster

[0094] All measurement would be repeated three times at least for each sample.

[0095] Stability test

[0096] The stability was evaluated by the variation of the UV absorption (Auv) over time (240 h) with examples storing the dark. All these measurements are repeated three times for each example.

[0097] Photostability test

[0098] The photostability test were conducted by measuring the UV absorption (Auv) of examples before and after 2-h UV radiation by using the UVP portable UV lamp. The UVP Portable UV light is available with shortwave of 254 nm (in a range of UVC wavelength) and longwave of 365 nm (in a range of UVA wavelength). All these measurements are repeated three times for each sample.

[0099] Sun Protection Factor (SPF) measurement

[0100] The SPF values of samples were measured by the UV-2000s ultraviolet transmittance analyser (Labsphere, USA) according to standard method set by ISO 24443. 32.5 mg samples were evenly transferred to the surface of polymethyl methacrylate (PMMA) plate (50 x 50 mm) using a disposable syringe, then coated as soon as possible by a covered finger. After being dried in the dark room for 15 minutes, and the tests were conducted. Every test was repeated for five times for each sample. Characteristics of Mg2Al-LDHs

[0101] The powder X-ray diffraction (XRD) data for Mg2Al-LDHs are shown in Fig. 2(a), which are typical diffractions of carbonated intercalated Mg2Al-LDHs with five characteristic Bragg reflections of (003), (006), (012), (110) and (113).

[0102] The TEM images show that uniform nanoparticles (nanoplatelets) of Mg2Al-LDHs were synthesized by hydrothermal treatment. The particles diameter increases with increased the hydrothermal temperature, for an average particle diameter of

[0103] 18±3 nm for Mg2Al-LDH-25,

[0104] 27±5 nm for Mg2Al-LDH-50,

[0105] 81±19 nm for Mg2Al-LDH-100,

[0106] 280±55 nm for Mg2Al-LDH-150

[0107] 376±73 nm for Mg2Al-LDH-200.

[0108] The respective TEM images are shown in (Fig. 2(b)- 2(f)).

[0109] Example 1 :

[0110] Cosmetic compositions, namely Comparative Example 1 (Com. Ex. 1) and Embodiments 1 - 5 (Em. 1- 5), were prepared by mixing an UV filter (Tinosorb®S Lite Aqua), Mg2Al-LDHs (for the Embodiments 1 to 5) and DI water in amounts as shown in Table 1.

[0111] UV absorbance results are shown in Table 1 and in Fig. 3. Fig. 3(a) shows that all the Mg2Al- LDHs have a negligible UV absorption, especially in the range of UVA and UVB, indicating that Mg2Al-LDHs have a low photoactivity. This result confirms that Mg2Al-LDHs meet the prerequisite of SPF booster.

[0112] The booster effect of Mg2Al-LDHs was tested. Fig. 3(b) shows that the UV absorption of the mixture of 0.1 wt% Mg2Al-LDH-150 and 0.0003 wt% Tinosorb® S Lite Aqua was enhanced evidently by comparing with the sole Tinosorb® S Lite Aqua in DI water. Fig. 3(c) and 3(d) show the addition of Mg2Al-LDHs having average particle diameter in a range of 18 - 376 nm also have a positive impact from 1.7 to 4.5-fold enhancement on the UV absorption compared to Tinosorb® S Lite Aqua (Com.Ex.l). Table 1

[0113] Example 2:

[0114] Cosmetic compositions, namely Comparative Examples 2-3 (Com. Ex. 2-3) and Embodiments 6-7 (Em. 6-7), were prepared by mixing the constituents shown in Table 2 in an amount as dictated in Table 2.

[0115] UV absorbance results are shown in Table 2 and Fig. 4. The addition of Mg2Al-LDH-150 enhance UV absorption for both UV filters Uvinul® T 150 and Uvinul® A Plus Granular. The boosting effect of Mg2Al-LDH-150 on Uvinul® T 150 and Uvinul® A Plus Granular is 3.8 and 3.5, respectively.

[0116] Table 2

[0117]

[0118] Example 3 :

[0119] Cosmetic compositions, namely Embodiments 8-11 (Em. 8-11), were prepared by mixing the constituents shown in Table 3 in the amounts as dictated in Table 3.

[0120] Fig. 5 and Table 3 show that the addition of Mg2Al-LDH-150 in a range of 0.03 wt% to 0.5 wt% enhances UV absorbance at 340 nm for Tinosorb®S Lite Aqua. The highest UV absorbance (highest boosting effect) was found for a 0.1 wt% Mg2Al-LDH-150 and even more significantly from a commercial perspective at only 0.05 wt% Mg2Al-LDH-150, the boosting effect still is about 3.7 times compared to the pure UV filter.

[0121] Table 3 Example 4:

[0122] Cosmetic compositions, namely Comparative Example 4 (Com. Ex. 4) and Embodiments 12- 17 (Em.12-17), were prepared by mixing commercial sunscreen (NIVEA SUN protect & moisture lotion SPF 15) with Mg2Al-LDH-150 in the amounts as dictated in Table 4.

[0123] SPF test result are shown in Table 4 and in Fig. 6.

[0124] Fig. 6 and Table 4 show that the SPF responses of commercial sunscreen also increased by addition of Mg2Al-LDH-150. Up to a 2-fold increase in SPF was measured at a slightly higher Mg2Al-LDH-150 loading.

[0125] Table 4

[0126] Example 5:

[0127] Cosmetic compositions, namely Embodiments 18 (Em.18), was prepared by mixing 0.1 wt% Mg2Al-LDH-150, 0.02 wt% NIVEA SUN protect & moisture lotion SPF 20, and 0.88 wt% DI water.

[0128] Stability and photostability test result are shown in Fig. 7. Fig. 7(a) shows that the UV absorbance of Em. 18 remained invariant after 240 h in the dark.

[0129] Fig. 7(b) shows that the UV absorbance of Em. 18 before and after 2-hour UVA and UVC radiation showed negligible differences. In conclusion, Mg2Al-LDH nanoplatelets have neither chemical nor photo-induced interactions with the sunscreen ingredients that may affect its optical performance.

[0130] Example 6:

[0131] Aqueous dispersions of the Mg2Al-LDHs platelets are prepared with the constituents in an amount as dictated in Table 5 and 6.

[0132] Optical scattering result are shown in Table 5 and Fig. 8-9.

[0133] As Fig. 8, Mg2Al-LDHs nanoplatelets having average particle size in a range of 18 - 376 nm show a high total scattering (TS) of between 66.9 to 92.5% between 290-400 nm. Upon increasing the particle diameter, the total scattering increases, reaching to a plateau at the particle diameter larger than 280 nm. Side scattering (SS) increased with particle diameter between 25 to 280 nm, and then slightly decreases. The highest side scattering was found for Mg2Al-LDH-150, with the proportion of side scattering at 62.6%. High forward scattering (52%) was found for smaller particle diameters, whereas low forward scattering (19.3%) for larger platelets. All Mg2Al-LDHs exhibited very low backward scattering (4.4% - 11.1%).

[0134] As Fig. 9, a high total scattering (81%) was found even at a small amount of Mg2Al-LDH- 150 (0.03 wt%). The total scattering increased with increasing amount of Mg2Al-LDH-150 and reaching to a plateau when amount of Mg2Al-LDH-150 is higher than 0.1 wt%. The highest proportion (62.6%) of side scattering was observed at 0.1 wt% Mg2Al-LDH-150. The low backward scattering was obtained over all amount of Mg2Al-LDH-150.

[0135] Fig 8(b) and Fig. 9(b) showed the boosting effect of Mg2Al-LDHs on Tinosorb®S Lite Aqua is highly correlated with the light scattering data of Mg2Al-LDHs aqueous suspension. The data also show that the boosting effect is most correlated to the side scattering.

[0136] Table 5

[0137]

[0138] Table 6

[0139] The features disclosed in the foregoing description and in the dependent claims may, both separately and in any combination thereof, be material for realizing the aspects of the disclosure made in the independent claims, in diverse forms thereof.

Claims

CLAIMS1. A cosmetic composition comprising: an UV filter and a sun protection factor booster; wherein the sun protection factor booster comprises a layered double hydroxide; and the layered double hydroxide has an average particle diameter in a range of 15 - 450 nm determined using TEM.

2. The cosmetic composition of claim 1, wherein the layered double hydroxide has an average particle diameter in a range of 225 - 350 nm determined using TEM.

3. The cosmetic composition of claim 1 or 2, wherein the layered double hydroxide a platelet shape.

4. The cosmetic composition of claim 3, wherein the layered double hydroxide is homogeneously distributed in the cosmetic composition.

5. The cosmetic composition of any one of the preceding claims, wherein the cosmetic composition comprises the layered double hydroxide in an amount of 0.03 - 10 wt%, based on total weight of the cosmetic composition.

6. The cosmetic composition of any one of the preceding claims, wherein the layered double hydroxide comprises: a) metal double hydroxide layers with the formula (I):[MZ+7- M^+X(OH)2] (I) wherein- M and M' are different from each other, and M and M' are each at least one metal cation,- z = 2;- y = 3 or 4,- 0 < x < 1; b) an interlayer anion; andc) optionally at least one selected form the group consisting of interlayer water; surfacebound water; interlayer solvent; and surface-bound solvent.

7. The cosmetic composition of claim 6, wherein, in formula (I), wherein M is Mg, Zn, Ca, or a mixture thereof.

8. The cosmetic composition of claim 6 or 7, wherein, when y is 3, M' is Al, Ti, or a mixture thereof, or, when y is 4, M' is, Ti,9. The cosmetic composition of any of the claims 6 to 8, wherein the interlayer anion is one or more selected from the group consisting of a halide anion, an inorganic oxyanion, and an anionic surfactant.

10. The cosmetic composition of any one of the claims 6 to 9, wherein the metal double hydroxide layers of layered double hydroxide is [NfYJ I'^ Olfy] wherein (1-x) / x = 1.8 to 5.

11. The cosmetic composition of any of the claims 6 to 10, wherein the metal double hydroxide layers of layered double hydroxide have the formula [Mz / M'' ..(0H)2] wherein (l-x)l x = 2 to 3.

12. The cosmetic composition of any of the claims 6 to 11, wherein the metal double hydroxide layers of the layered double hydroxide have the formula [Mg / AA1.(OH)2] wherein (1-x) / x = 2-3 and the interlayer anion is carbonate.

13. The cosmetic composition of any one of the preceding claims, wherein the UV filter is selected from the group consisting of titanium dioxide, zinc oxide, kaolin, talc, calamine, benzophenone and derivatives thereof, dibenzoylmethane and derivatives thereof, anthranilate and derivatives thereof, benzylidene camphor and derivatives thereof, aminobenzoic acid and derivatives thereof, cinnamic acid and derivatives thereof, salicylate and derivatives thereof, benzimidazole and derivatives thereof, benzotriazole derivatives thereof, triazine, triazole derivatives, ascorbic acid, P- carotene, a-tocopherol, aspirin, indomethacin, corticosteroids, selenium, retinol, green tea polyphenol, and a mixture of two or more thereof.

14. The cosmetic composition of any one of the preceding claims, wherein the cosmetic composition further comprises a photostabilizer, an antioxidant, a moisturizer, an emulsifier, a dispersant, a film former, a thickener, a sensory enhancer, a vitamin, anoil control agent, an anti-aging active, a skin lightening agent, a tanning active, an antiperspirant active, an antimicrobial active, a preservative, a fragrance, a solvent, or a mixture of two or more thereof.

15. The cosmetic composition of any one of the preceding claims, wherein the cosmetic composition is a sunscreen composition, a skincare composition, a hair care composition, a skin-tanning composition, a cosmetic composition, a make-up composition, a lip balm, a skin facial peeling composition, a moisturizing composition, an anti-aging skincare composition or a mixture of two or more thereof thereof.

16. A process for the preparation of the cosmetic composition any one of the preceding claims, wherein the process comprises a step of mixing the UV filter and SPF booster.

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