FIELD OF THE INVENTION

This invention relates generally to personal care compositions that are useful as oil gel formulations. The personal care compositions containing UV absorbing agents, hydrophobic ester oil, and acrylic copolymers.

BACKGROUND

Personal care sunscreen compositions contain a variety of additives, in addition to UV absorbing agents, that provide a wide array of benefits to the composition. One class of additives are oil thickeners that provide viscosity enhancements and impart good aesthetics, such as good sensory feel and clarity. Oil thickening agents that are known in the art include, for example, styrene-ethylene/butadiene-styrene copolymers, polyamide polymers, and cellulose-based polymers. These thickeners, however, come with certain drawbacks, including insufficient viscosity enhancement, high formulation temperature, and lack of consistency in viscosity control in consumer product formulations.

To this end, polyacrylate oil gels have been utilized in the art. For example, WO

2014/204937 Al discloses personal care compositions comprising a polyacrylate oil gel containing a cosmetically acceptable hydrophobic ester oil and a polymer including at least two polymerized units. The prior art does not, however, disclose a polyacrylate oil gel according to the present invention which achieves the significant viscosity performance at low formulation temperatures while also providing a clear formulation. Accordingly, there is a need to develop thickeners that provide significant viscosity enhancements to compositions containing UV absorbing agents, while not suffering from the drawbacks of the prior art.

STATEMENT OF INVENTION

One aspect of the invention provides a personal care composition comprising (a) at least one cosmetically acceptable hydrophobic ester oil, (b) at least one UV absorbing agent, and (c) one or more polymers comprising polymerized structural units of (i) 98 to 99.5 weight % of C ₄ - Cs (meth)acrylate monomers, and (ii) 0.5 to 2 weight % of (meth)acrylic acid monomer.

Another aspect of the invention provides a method for protecting skin from UV damage, comprising topically administering to the skin an effective amount of a personal care composition comprising (a) at least one cosmetically acceptable hydrophobic ester oil, (b) at least one UV absorbing agent, and (c) one or more polymers comprising polymerized structural units of (i) 98 to 99.5 weight % of C ₄ -Cs (meth)acrylate monomers, and (ii) 0.5 to 2 weight % of (meth)acrylic acid monomer.

DETAILED DESCRIPTION

The inventors have now surprisingly found that personal care sunscreen compositions comprising a UV absorbing agent, hydrophobic ester oil, and polymers having a high weight percent of polymerized structural units of C ₄ -Cs (meth)acrylate monomer, and a small weight percent of (meth)acrylic acid monomer, provide significant viscosity enhancements while retaining clarity in personal care sunscreen formulations. Accordingly, the present invention provides in one aspect a personal care composition comprising (a) hydrophobic ester oil, (b) UV absorbing agent, and (c) one or more polymers comprising polymerized structural units of (i) 98 to 99.5 weight % of C ₄ -Cs (meth)acrylate monomers, and (ii) 0.5 to 2 weight % of (meth)acrylic acid monomer.

In the present invention, "personal care" is intended to refer to cosmetic and skin care compositions for application to the skin, including, for example, leave on application to the skin, such as lotions, creams, gels, gel creams, serums, toners, wipes, liquid foundations, make-ups, tinted moisturizer, oils, face/body sprays, topical medicines, and sunscreen compositions.

"Sunscreen compositions" refers to compositions that protect the skin from UV damage.

"Personal care" relates to compositions to be topically administered (i.e., not ingested).

Preferably, the personal care composition is cosmetically acceptable. "Cosmetically acceptable" refers to ingredients typically used in personal care compositions, and is intended to underscore that materials that are toxic when present in the amounts typically found in personal care compositions are not contemplated as part of the present disclosure. The compositions of the invention may be manufactured by processes well known in the art, for example, by means of conventional mixing, dissolving, granulating, emulsifying, encapsulating, entrapping or lyophilizing processes.

As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term "polymer" includes the terms "homopolymer," "copolymer," and "terpolymer." As used herein, the term "polymerized structural units" of a given monomer refers to the remnant of the monomer after polymerization. As used herein, the term "(meth)acrylate" refers to either acrylate or methacrylate, and the term "(meth)acrylic" refers to either acrylic or methacrylic. As used herein, the term "substituted" refers to having at least one attached chemical group, for example, alkyl group, alkenyl group, vinyl group, hydroxyl group, carboxylic acid group, other functional groups, and combinations thereof.

The inventive personal care compositions include one or more polymers comprising structural units of C ₄ -Cs (meth)acrylate monomers and (meth)acrylic acid monomers. Suitable C ₄ -Cs (meth)acrylate monomers include, for example, n-butyl (meth)acrylate, i-butyl

(meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and 2-phenylethyl (meth)acrylate. Preferably, the C ₄ -Cs (meth)acrylate monomers comprise one or more of i-butyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate. In certain embodiments, the polymer comprises polymerized structural units of C ₄ -Cs (meth)acrylate monomers in an amount of from 98 to 99.5 weight %, preferably from 98.2 to 99.3 weight %, and more preferably from 98.9 to 99.1 weight %, based on the total weight of the polymer. In certain embodiments, the C ₄ -Cs (meth)acrylate monomers comprise i-butyl methacrylate and 2-ethylhexyl methacrylate in a ratio of from 9: 1 to 2:3, preferably from 3:2 to 2:3, and more preferably 1: 1.

The polymers of the inventive personal care compositions also comprise structural units of (meth)acrylic acid monomer. In certain embodiments, the polymer comprises polymerized structural units of (meth)acrylic acid monomer in an amount of from 0.5 to 2 weight %, preferably from 0.7 to 1.8 weight %, and more preferably from 0.9 to 1.1 weight %, based on the total weight of the polymer.

In certain embodiments, the polymers have an average particle size of from 50 to 2,000 nm, preferably of from 75 to 1,100 nm, and more preferably of from 100 to 200 nm. Polymer molecular weights can be measured by standard methods such as, for example, size exclusion chromatography or intrinsic viscosity. In certain embodiments, the polymers are present in the personal care composition in an amount of from 0.1 to 20 weight %, preferably from 2 to 13.5, and more preferably from 3 to 7 weight %, based on the total weight of the personal care composition.

Suitable polymerization techniques for preparing the polymers contained in the inventive personal care compositions include, for example, emulsion polymerization. Aqueous emulsion polymerization processes typically are conducted in an aqueous reaction mixture, which contains at least one monomer and various synthesis adjuvants, such as the free radical sources, buffers, and reductants in an aqueous reaction medium. In certain embodiments, a chain transfer agent may be used to limit molecular weight. The aqueous reaction medium is the continuous fluid phase of the aqueous reaction mixture and contains more than 50 weight % water and optionally one or more water miscible solvents, based on the weight of the aqueous reaction medium. Suitable water miscible solvents include, for example, methanol, ethanol, propanol, acetone, ethylene glycol ethyl ethers, propylene glycol propyl ethers, and diacetone alcohol. In certain embodiments, the aqueous reaction medium contains more than 90 weight % water, preferably more than 95 weight % water, and more preferably more than 98 weight % water, based on the weight of the aqueous reaction medium.

The polymers of the present invention may be isolated by a spray drying process. While spray drying is one preferred embodiment of how to produce the dry powder, other suitable methods include, for example, freeze drying, a two-step process including the steps of (i) pan drying the emulsion and then (ii) grinding the pan dried material into a fine powder, coagulation of the acrylic emulsion and collection of the powder by filtration followed by washing and drying, fluid bed drying, roll drying, and freeze drying. Suitable techniques for spray drying the polymer beads of the present invention are known in the art, for example, as described in US 2014/0113992 Al. In certain embodiments, anti-caking agents are used when spray drying the polymer beads. Suitable anti-caking agents include, for example, mineral fillers (e.g., calcium carbonate, kaolin, titanium oxide, talc, hydrated alumina, bentonite, and silica), solid polymer particles with a T _g or T _m greater than 60°C (e.g., polymethylmethacrylate, polystyrene, and high density polyethylene), and water soluble polymers with a T _g greater than 60°C (e.g., polyvinyl alcohol and methylcellulose). The anti-caking agent can be mixed in the acrylic suspension prior to spray drying or introduced as a dry powder in the spray drying process. In certain

embodiments, the anti-caking agent coats the polymer beads to prevent the beads from sticking to each other inner wall of the dryer. In certain embodiments, the anti-caking agent is present in an amount of from 0 to 20 weight %, and more preferably from 0.01 to 10 weight %, based on the total weight of the polymer beads.

The personal care compositions of the present invention also contain a cosmetically acceptable hydrophobic ester oil. In general, any hydrophobic ester oil or mixtures thereof which are toxicologic ally safe for human or animal use may constitute the oil base of the present invention. In certain embodiments, the hydrophobic ester oil comprises aliphatic C8-C24 alkyl triglycerides. Suitable hydrophobic ester oils include, for example, caprylic/capric triglycerides, saturated fatty esters and diesters (e.g., isopropyl palmitate, octyl palmitate, butyl stearate, isocetyl stearate, octadodecyl stearate, octadodecyl stearoyl stearate, diisopropyl adipate, and dioctyl sebacate), and animal oils and vegetable oils (e.g., mink oil, coconut oil, soybean oil, palm oil, corn oil, cocoa butter, sesame oil, sunflower seed oil, jojoba oil, olive oil, and lanolin oil). In certain embodiments, the hydrophobic ester oil is diffused in an oil base. Suitable oil bases include any oil or mixture of oils which are conventionally used in personal care products including, for example, paraffin oils, paraffin waxes, and fatty alcohols (e.g., stearyl alcohol, isostearyl alcohol, and isocetyl alcohol). In certain preferred embodiments, the hydrophobic ester oil comprises one or more of caprylic/capric triglycerides and sunflower seed oil. In certain embodiments, the hydrophobic ester oils are present in the personal care composition in an amount of from 30 to 98.9 weight %, preferably from 40 to 88 weight %, and more preferably from 53 to 77 weight %, based on the total weight of the personal care composition.

The personal care compositions of the present invention also contain at least one UV absorbing agent. Suitable UV absorbing agents include, for example, oxybenzone,

dioxybenzone, sulisobenzone, menthyl anthranilate, para-aminobenzoic acid, amyl

paradimethylaminobenzoic acid, octyl para-dimethylaminobenzoate, ethyl 4-bis (hydroxypropyl) para-aminobenzoate, polyethylene glycol (PEG-25) para-aminobenzoate, ethyl 4-bis

(hydroxypropyl) aminobenzoate, diethanolamine para-methyoxycinnamate, 2-ethoxyethyl para- methoxycinnamate, ethylhexyl para-methoxycinnamate, octyl para-methoxycinnamate, isoamyl para-methoxycinnamate, 2-ethylhexyl-2-cyano-3,3-diphenyl-acrylate, 2-ethylhexyl salicylate, homomenthyl salicylate, glyceryl aminobenzoate, triethanolamine salicylate, digalloyl trioleate, lawsone with dihydroxyacetone, 2-phenylbenzimidazole-5-sulfonic acid, 4-methylbenzylidine camphor, and avobenzone. Alternatively, UV absorbing agents such as triazines, benzotriazoles, vinyl group-containing amides, cinnamic acid amides and sulfonated benzimidazoles may also be used. In certain embodiments, the personal care compositions include UV absorbing agents in an amount of from 1 to 50 weight %, preferably 10 to 45 weight %, and more preferably from 20 to 40 weight %, based on the total weight of the personal care composition.

The personal care compositions according to the present invention may be formulated by conventional mixing processes known to those skilled in the art. In certain embodiments, the formulation temperature is from 5 to 150°C, preferably from 25 to 70°C. The order of addition of the polymer particles, hydrophobic ester oil, and UV absorbing agent is not consequential, and thus can be mixed in any order of addition.

In certain embodiments, the inventive personal care compositions also include a dermatologically acceptable carrier. Such material is typically characterized as a carrier or a diluent that does not cause significant irritation to the skin and does not negate the activity and properties of active agent(s) in the composition. Examples of dermatologically acceptable carriers that are useful in the invention include, without limitation, water, such as deionized or distilled water, emulsions, such as oil-in-water or water-in-oil emulsions, alcohols, such as ethanol, isopropanol or the like, glycols, such as propylene glycol, glycerin or the like, creams, aqueous solutions, oils, ointments, pastes, gels, lotions, milks, foams, suspensions, powders, or mixtures thereof. The aqueous solutions may contain cosolvents, e.g., water miscible cosolvents. Suitable water miscible cosolvents include, for example, ethanol, propanol, acetone, ethylene glycol ethyl ethers, propylene glycol propyl ethers, and diacetone alcohol. In some

embodiments, the composition contains from about 99.99 to about 50 percent by weight of the dermatologically acceptable carrier, based on the total weight of the composition.

Other additives may be included in the compositions of the invention such as, but not limited to, abrasives, absorbents, aesthetic components such as fragrances, pigments,

colorings/colorants, essential oils, skin sensates, astringents (e.g., clove oil, menthol, camphor, eucalyptus oil, eugenol, menthyl lactate, witch hazel distillate), preservatives, anti-caking agents, a foam building agent, antifoaming agents, antimicrobial agents (e.g., iodopropyl

butylcarbamate), antioxidants, binders, biological additives, buffering agents, bulking agents, chelating agents, chemical additives, cosmetic astringents, cosmetic biocides, denaturants, drug astringents, external analgesics, film formers or materials, e.g., polymers, for aiding the film- forming properties and substantivity of the composition (e.g., copolymer of eicosene and vinyl pyrrolidone), opacifying agents, pH adjusters, propellants, reducing agents, sequestrants, skin bleaching and lightening agents (e.g., hydroquinone, kojic acid, ascorbic acid, magnesium ascorbyl phosphate, ascorbyl glucosamine), skin-conditioning agents (e.g., humectants, including miscellaneous and occlusive), skin soothing and/or healing agents (e.g., panthenol and derivatives (e.g., ethyl panthenol), aloe vera, pantothenic acid and its derivatives, allantoin, bisabolol, and dipotassium glycyrrhizinate), skin treating agents, vitamins (e.g., Vitamin C) and derivatives thereof, silicones, and fatty alcohols. The amount of option ingredients effective for achieving the desired property provided by such ingredients can be readily determined by one skilled in the art.

The skin care compositions of the present invention are useful for the treatment and protection of skin, including, for example, protection from UV damage, moisturization of the skin, prevention and treatment of dry skin, protection of sensitive skin, improvement of skin tone and texture, masking imperfections, and inhibition of trans-epidermal water loss. Thus, in one aspect the present invention provides that the personal care compositions may be used in a method for protecting skin from UV damage comprising topically administering to the skin a composition comprising (a) at least one cosmetically acceptable hydrophobic ester oil, (b) at least one UV absorbing agent, and (c) one or more polymers comprising polymerized structural units of (i) 98 to 99.5 weight % of C ₄ -Cs (meth)acrylate monomers, and (ii) 0.5 to 2 weight % of (meth)acrylic acid monomer.

In practicing the methods of the invention, the skin care compositions are generally administered topically by applying or spreading the compositions onto the skin. A person of ordinary skill in the art can readily determine the frequency with which the compositions should be applied. The frequency may depend, for example, on the level of exposure to UV light that an individual is likely to encounter in a given day and/or the sensitivity of the individual to UV light. By way of non-limiting example, administration on a frequency of at least once per day may be desirable. Some embodiments of the invention will now be described in detail in the following

Examples.

EXAMPLES Example 1

Preparation of Exemplary Polymer and Comparative Polymers

Exemplary polymers in accordance with the present invention and comparative polymers contain the components recited in Table 1. Table 1. Exemplary and Comparative Polymers Particles

iBMA = isobutyl methacrylate

EHMA = ethylhexyl methacrylate MAA = methacrylic acid

MMA = methyl methacrylate

BA = butyl acrylate

ALMA = allyl methacrylate

Synthesis of Exemplary Polymers and Comparative Polymers

Synthesis of exemplary polymer P-E4 was carried out as follows. A three liter round bottom flask was equipped with a mechanical overhead stirrer, heating mantle, thermocouple, condenser and inlets for the addition of monomer, initiator and nitrogen. The kettle was charged with 470 grams deionized water and 7.46 grams of DS-4 (Polystep A-16-22: sodium dodecylbenzene sulfonate from Stepan). The kettle contents were set to stir with a nitrogen flow and heated to 87-89°C. To a plastic lined vessel, 17.3 grams of DS-4 and 181.65 grams deionized water was added and mixed with overhead stirring. 277.2 grams of z ^' so-butyl methacrylate, 277.2 grams of 2-ethylhexyl methacrylate and 5.6 grams of methacrylic acid were charged to the vessel and allowed to form a smooth, stable monomer emulsion. An initial catalyst charge of 0.16 grams of ammonium persulfate and 12.71 grams of deionized water was prepared and set aside. A kettle buffer solution of 1.92 grams of ammonium bicarbonate and 12.71 grams of deionized water was prepared and set aside. A preform seed of 22.38 grams was removed from the stable monomer emulsion and put into a small beaker. A rinse of 16.8 grams of deionized water was prepared. A co-feed catalyst charge of 0.16 grams of ammonium persulfate and 49.22 grams of deionized water was prepared and set aside.

When the kettle was at temperature, the kettle buffer solution and initial catalyst solution were added to the reactor, followed by the perform seed and rinse. The reaction was monitored for a small exotherm. After the exotherm, the temperature control was adjusted to 83-85°C. The monomer emulsion feed was added to the kettle, sub-surface, at a rate of 4.46 grams/minute for 15 minutes. After 15 minutes, the rate was increased to 8.93 grams/minutes for 75 minutes, giving a total feed time of 90 minutes. While the monomer emulsion feed was added to the kettle, the co-feed catalyst solution was also added over 100 minutes at a rate of 0.49

grams/minute. At the completion of the feeds, 16.8 grams of deionized water was added as a rinse. The reaction was then held for 20 minutes at 83-85°C.

During the hold, a chase promoter of 3.77 grams of a 0.15% iron sulfate heptahydrate solution was prepared. A chase activator solution of 1.12 grams of isoascorbic acid dissolved in 36.40 grams of deionized water was prepared. A chase catalyst solution of 2.14 grams of 70% tert-butyl hydroperoxide in 35.40 grams of deionized water was prepared.

At 80°C, the chase promoter solution was added as a shot to the kettle. The kettle contents were then cooled to 70°C, while adding the chase activator and chase catalyst solutions separately by syringe over 60 minutes at a feed rate of 0.63 grams/minute. The reaction was held for 10 minutes, and then cooled to room temperature. At room temperature, the emulsion was filtered through a 100 mesh bag.

Exemplary polymers P-El, P-E2, P-E3, and P-E5 and comparative polymer P-C2 were prepared substantially as described above, with the appropriate changes in monomer and monomer amounts as recited in Table 1.

Synthesis of Comparative Polymer P-Cl

Synthesis of comparative polymer P-Cl was prepared according to the procedi described in Example 1 of WO 2014/204937. Example 2

Particle Size Characterization of Exemplary Polymers

Exemplary and comparative polymers as prepared in Example 1 were evaluated for particle size as shown in Table 2.

Table 2. Particle Size Characterization

The particle size distributions was determined by light scattering using a Malvern Mastersizer 2000 Analyzer equipped with a 2000uP module. Approximately 0.5 g of polymer emulsion samples were pre-diluted into 5 mL of 0.2 weight % active Triton 405 in degassed, DI water (diluents). The pre-diluted sample was added drop-wise to the diluent filled 2000uP module while the module was pumped at 1100 rpm. Red light obscurations were targeted to be between 4 and 8%. Samples were analyzed using a Mie scattering module (particle real refractive index of 1.48 and absorption of zero: Diluent real refractive index of 1.330 with absorption of zero). A general purpose (spherical) analysis model with "normal sensitivity" was used to analyze the diffraction patterns and convert them into particle size distributions. Example 3

Spray Drying of Exemplary Polymers and Comparative Polymer P-C2

Exemplary polymers and comparative polymer P-C2 as prepared in Example 1 were spray dried according to the following procedure. A two-fluid nozzle atomizer was equipped on a Mobile Minor spray dryer (GEA Process Engineering Inc.). The spray drying experiments were performed under an inert atmosphere of nitrogen. The nitrogen supplied to the atomizer at ambient temperature was set at 1 bar and 50% flow, which is equivalent to 6.0 kg/hour of flow rate. The polymer emulsion was fed into the atomizer at about 30 niL/min using a peristaltic pump (Masterflex L/S). Heated nitrogen was used to evaporate the water. The inlet temperature was set at 140°C, and the outlet temperature was equilibrated at 40-50°C by fine tuning the emulsion feed rate. The resulting polymer powder was collected in a glass jar attached to the cyclone and subsequently vacuum dried at room temperature to removed residual moisture.

Example 4

Preparation of Exemplary and Comparative Sunscreen Formulations

Exemplary sunscreen formulations according to the present invention including exemplary polymers as prepared in Example 3, and comparative sunscreen formulations including comparative polymers as prepared in Example 3, contain the components recited in Table 3. Table 3. Exemplary and Comparative Sunscreen Formulations

P-E5 — — — — — — 5.0 5.0 — —

P-Cl — — — — — — — — 5.0 —

P-C2 — — — — — — — — — 5.0

Total 100 100 100 100 100 100 100 100 100 100

Available from BASF

² Available from Symrise

3Available from ISP Chemicals Inc.

4Available from Evonik Industries AG

5Available from Honeywell (Fluka)

6Available from Croda International

7Available from RITA Corporation

8 Available from Sasol Limited

9Available from Spectrum Chemical

Exemplary and comparative sunscreen formulations were formulated by mixing the exemplary polymers as prepared in Example 3 together with the other components in the amounts specified in Table 3 under stirring at 500-1000 rpm at 50-70°C for 60-90 minutes.

Example 5

Turbidity of Exemplary and Comparative Sunscreen Formulations

The turbidity of exemplary and comparative sunscreen formulations as prepared in Example 4 are shown in Table 4.

Table 4. Turbidity of Exemplary and Comparative Sunscreen Formulations

SE4 1.49

SE5a 1.21

SE5b 0.76

SCI unstable

SC2 unstable

The turbidity of each sunscreen sample formulation was evaluated using a Laboratory Hach Turbidimeter. Samples were placed in the light path using measuring cells of standard dimensions (1 cm). The light passing through the solution (i.e., non scattered) was measured with a photocell. The greater the light measured, the less the turbidity. For a high clarity formulation, the turbidity is below 20. The results demonstrate that the inventive sunscreen formulations exhibit superior clarity.

Example 6

Rheology Characterization of Exemplary and Comparative Sunscreen Formulations

Viscosities of sunscreen sample formulations were measured using a Rheometrics RFS III Rheometer with a Couette geometry (bob diameter = 32 mm, cup diameter = 34 mm, bob length = 34 mm). All measurements were performed at a strain of 2%, within the linear viscoelastic regime. All analyses were performed at 20°C, and isothermal frequency sweep was conducted. A logarithmic step ramp method was used ranging over the frequency range of 0.1- 100 s ^"1 with 10 data points per decade after an initial 2 minute equilibration.

The viscosity versus shear rate rheology profiles for exemplary sunscreen formulations against the Control are shown in Table 5. Table 5. Viscosity of Sunscreen Formulations

The exemplary sunscreen formulations demonstrated an increase in viscosity and shear thinning behavior, which is highly desirable in sunscreen formulations.