WO2017075773A1

WO2017075773A1 - Polycaprolactone-polyurethane microparticles coated with inorganic metal oxides and methods for the preparation thereof

Info

Publication number: WO2017075773A1
Application number: PCT/CN2015/093776
Authority: WO
Inventors: Wei Lu; O'connor YING; Xiao Yi PANG; Tong Sun; Wai Kin LEE
Original assignee: Dow Global Technologies LLC; Rohm and Haas Co
Current assignee: Dow Global Technologies LLC; Rohm and Haas Co
Priority date: 2015-11-04
Filing date: 2015-11-04
Publication date: 2017-05-11
Anticipated expiration: 2018-05-04

Abstract

Provided are compositions and methods that are useful for personal care compositions. The compositions comprise polycaprolactone-polyurethane microparticles coated with inorganic metal oxide particles, wherein the weight ratio of inorganic metal oxide to polycaprolactone-polyurethane is in a range of from 5:95 to 2:8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns. Also provided are methods of preparation of such compositions, as well as methods for lightening skin tone comprising topically administering such compositions to the skin, and methods for improving visible light scattering of a composition including a pigment grade inorganic metal oxide particle comprising adding to such composition a voided latex particle.

Description

POLYCAPROLACTONE-POLYURETHANE MICROPARTICLES COATED WITH INORGANIC METAL OXIDES AND METHODS FOR THE PREPARATION THEREOF

FIELD OF THE INVENTION

This invention relates generally to polycaprolactone-polyurethane microparticles coated with an inorganic metal oxide, their use in personal care compositions, and methods of preparation for the same.

BACKGROUND

Personal care compositions contain a variety of additives that provide a wide array of benefits to users, such as treating skin to alter its color or tone, for example, by skin lightening. Pigment grade inorganic metal oxide particulate light scatterers, such as titanium dioxide, are effective skin lightening agents. Providing a whitening appearance with satisfactory aesthetic and sensory properties, e.g., optical and tactile benefits, is a challenging goal to meet, however. Most current technology, for example, are effective for providing whitening appearance, but suffer from an artificial whitening effect, highlighting the difference between lines and flat surfaces in the skin which cause skin tone unevenness. Known technologies also fail to provide a desirable sensory feel to keep the skin in a smooth and supple condition, without suffering from negative aesthetic qualities, such as greasiness or stickiness.

Personal care compositions comprising light scatterers and UV absorbing agents have been disclosed. For example, U.S. Patent Application Publication No. US 2006/0286048 discloses the preparation of dustless pigments for use in cosmetic products such as foundations, lip sticks, lotions, and creams, wherein the pigments have been chemically immobilized with one or more surface-active agents and coated with an oil. The prior art suffers, however, from poor aesthetic properties such as unpleasant visual appearance and lack of smoothness after deposition on skin.

Consequently, there is a need to develop new additives for use in personal care formulations that provide good deposition of inorganic metal oxides while also providing desirable aesthetic and sensorial properties.

STATEMENT OF INVENTION

One aspect of the invention provides a composition comprising polycaprolactone-polyurethane microparticles coated with inorganic metal oxide particles, wherein the weight ratio of inorganic metal oxide particles to the polycaprolactone-polyurethane microparticles is in a range of from 5: 95 to 2: 8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns.

In another aspect, the present invention provides a process for preparing a polycaprolactone-polyurethane microparticle coated with inorganic metal oxide particles comprising the steps of (a) mixing a pre-polymer reaction mixture comprising an isocyanate, a polyol, and polycaprolactone to provide a polycaprolactone-polyurethane pre-polymer, (b) reacting the polyurethane pre-polymer mixture in the presence of an amine catalyst and a polyvinyl alcohol to provide a polycaprolactone-polyurethane slurry containing polycaprolactone-polyurethane microparticles having an average particle size of 0.1 to 50 microns, (c) mixing the polyurethane slurry with an inorganic metal oxide suspension to provide a polycaprolactone-polyurethane/inorganic metal oxide composite dilution, and (d) spray drying the polycaprolactone-polyurethane/inorganic metal oxide composite dilution to provide an inorganic metal oxide coated polycaprolactone-polyurethane microparticle.

Another aspect of the present invention provides a method for lightening skin tone comprising topically administering to the skin an effective amount of a personal care composition comprising polycaprolactone-polyurethane microparticles coated with pigment grade inorganic metal oxide particles, wherein the weight ratio of pigment grade inorganic metal oxide particles to the polycaprolactone-polyurethane microparticles is in a range of from 5: 95 to 2: 8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns.

In yet another aspect, the invention provides a method for improving visible light scattering of a composition comprising adding to said composition from 0.1 to 30 weight ％of polycaprolactone-polyurethane microparticles coated with pigment grade inorganic metal oxide particles, based on the total weight of the composition, wherein the wherein the weight ratio of pigment grade inorganic metal oxide particles to the polycaprolactone-polyurethane microparticles is in a range of from 5: 95 to 2: 8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the particle morphology of (a) polycaprolactone-polyurethane microparticles, (b) polycaprolactone-polyurethane microparticles coated with titanium dioxide in a titanium dioxide to polycaprolactone weight ratio of 0.5: 9.5, (c) polycaprolactone-polyurethane microparticles coated with titanium dioxide in a titanium dioxide to polycaprolactone weight ratio of 1: 9, (d) polycaprolactone-polyurethane microparticles coated with titanium dioxide in a titanium dioxide to polycaprolactone weight ratio of 1.5: 8.5, and (e) polycaprolactone-polyurethane microparticles coated with titanium dioxide in a titanium dioxide to polycaprolactone weight ratio of 2: 8.

FIG. 2 shows an energy-dispersive X-ray spectrum of titanium dioxide coated polycaprolactone-polyurethane microparticles having a titanium dioxide to polycaprolactone-polyurethane weight ratio of 10: 90.

FIG. 3 shows the lightness and blurring effect of films cast from various exemplary and comparative skin lightening compositions.

DETAILED DESCRIPTION

The inventors have now surprisingly found that polycaprolactone-polyurethane ( “PCL-PU” ) microparticles coated with inorganic metal oxide particles provide superior aesthetics benefits, e.g., an increased blurring /skin lightening effect after deposition as compared to pigment grade metal oxides when applied to the skin, while also providing a pleasant tactile feel when incorporated into skin care formulations. Accordingly, the present invention provides in one aspect PCL-PU microparticles coated with an inorganic metal oxide, wherein the weight ratio of inorganic metal oxide to PCL-PU is in a range of from 5: 95 to 2: 9, and the polyurethane microparticles have an average particle size of 0.1 to 50 microns.

In the present invention, “personal care” is intended to refer to cosmetic and skin care compositions for application to the skin, including, for example, body washes and cleansers, as well as 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 sunscreens. In the present invention, “personal care” is also intended to refer to hair care compositions including, for example, shampoos, leave-on conditioners, styling gels, hairsprays, and mousses. 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.

The PCL-PU microparticles useful in the present invention may be formed by the combination of a polyol and an isocyanate and a catalyst promoting the reaction between the two components. Accordingly, one aspect of the present invention provides a process for preparing a PCL-PU microparticle coated with inorganic metal oxide particles comprising the steps of (a) mixing a pre-polymer reaction mixture comprising an isocyanate, a polyol, and polycaprolactone to provide a PCL-PU pre-polymer, (b) reacting the PCL-PU pre-polymer in the presence of a catalyst and a polyvinyl alcohol to provide a PCL-PU slurry containing PCL-PU microparticles, (c) mixing the PCL-PU slurry with an inorganic metal oxide suspension to provide a PCL-PU/inorganic metal oxide composite dilution, and (d) spray drying the PCL-PU/inorganic metal oxide composite dilution to provide a PCL-PU microparticle coated with inorganic metal oxides.

Isocyanates useful in the pre-polymer reaction mixture are those known in the art including an isocyanate functional group, i.e., -N＝C＝O. Suitable isocyanates include, for example, toluene diisocyanate, methylene diisocyanate, isophorone diisocyanate, cyclohexane-1, 3-diisocyanate, cyclohexane-1, 4-diisocyanate, hexamethylene diisocyanate, m- tetramethyloxylene diisocyanate, 2, 2, 4-trimethyl hexamethylene diioscyanate, 2, 4, 4-trimethyl hexamethylene diioscyanate, 2, 5-norbornane diisocyanate, m-xylene diisocyanate, bis-(cyclohexyl isocyanate) methane, and combinations thereof. Preferably, the isocyanate comprises isophorone diisocyanate.

Polyols useful in the pre-polymer reaction mixture are those known in the art as useful in the production of polyurethanes. Suitable polyols include, for example, ethylene glycol, diethylene glycol, 1, 4-butane diol, poly (tetramethylene ether glycol) , polyoxypropylene glycol, polyether triol, and polyether tetrol. Preferably, the polyol comprises poly (tetramethylene ether glycol) .

Polycaprolactones ( “PCLs” ) useful in the present invention are a crystalline, thermoplastic aliphatic polyester resin having a melting point of 60℃, and are also characterized as being biodegradable. Suitable PCLs include, for example, those having a number average molecular weight of from 1,000 to 100,000, preferably from 1,000 to 30,000, and more preferably from 1,000 to 10,000.

Catalysts useful in the reaction of the pre-polymer mixture are those known in the art as useful in the production of polyurethanes, including, for example, amine catalysts and organometallic catalysts. Suitable amine catalysts include, for example, ethylenediamine (EDA) , triethylenetetramine (TETA) , isophoronediamine (IDPA) , diethylenetriamine (DETA) , N, N-dimethylcyclohexylamine, N, N-dimethylcetylamine, diamino-bicyclooctane, and combinations thereof. Suitable organometallic include, for example, stannous octoate, dibutyltin dilaurate, and combinations thereof. Preferably, the catalyst comprises DETA.

Polyvinyl alcohols useful in the present invention are polyhydoxy polymers having a polyethylene backbone with pendent hydroxyl groups. Suitable polyvinyl alcohols include, for example, those having a number average molecular weight of from 10,000 to 150,000, preferably from 20,000 to 80,000, and more preferably from 50,000 to 60,000.

In certain embodiments, the polycaprolactone-polyurethane microparticles in the PCL-PU slurry have an average particle size of from 0.1 to 50 microns, preferably from 1 to 40 microns, and more preferably from 5 to 30 microns.

The PU-PCL microparticles in the PCL-PU slurry are mixed with an inorganic metal oxide suspension prior to being spray dried. Suitable inorganic metal oxide suspensions include, for example, 1 to 20 weight ％, preferably 5 to 10 weight ％, inorganic metal oxide in water, by weight of the suspension. Suitable inorganic metal oxide particles include, for example, zinc oxide (ZnO) , titanium dioxide (TiO₂) , and mixtures thereof. In certain embodiments, the inorganic metal oxide particles are pigment grade ZnO or pigment grade TiO₂ that produce a white appearance caused by light scattering. In certain embodiments, pigment grade inorganic metal oxide particles having good pigmentation properties and have an average particle size in the range of from 15 nm to 1,000 nm, preferably from 50 nm to 400 nm, and more preferably from 100 nm to 300 nm. Suitable TiO₂ particles include, for example, those commercially available under the trade names AQUASPERSABIL Rutile TiO₂ and OLEOSPERSE TiO₂ from Presperse Corporation, and TITANIX TiO₂ from Tyca Corporation.

In certain embodiments, the PCL-PU/inorganic metal oxide composite dilution contains the inorganic metal oxide particles and PU-PCL microparticles in a weight ratio of from 5: 95 to 2: 8, preferably from 1: 9 to 15: 85.

Spray drying methods useful for forming the inorganic metal oxide coated PCL-PU microparticles are known in the art. Any known spray drying method can be used in the present invention. 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 A1. In certain embodiments, the inorganic metal oxide coated PCL-PU microparticles of the present invention exhibit a “raspberry like” morphology containing a plurality of inorganic metal oxide particles coating the surface of the PCL-PU microparticle. The resulting inorganic metal oxide coated PCL-PU microparticles have, in certain embodiments, an average particle size of from 1 to 50 microns, preferably 1 to 20 microns, and more preferably 5 to 15 microns.

A person of ordinary skill in the art can readily determine the effective inorganic metal oxide coated PCL-PU microparticles that should be used in a particular composition in order to provide the desired benefits described herein (e.g., an effective skin lightening composition) . By way of non-limiting example, the amount of inorganic metal oxide coated PCL-PU microparticles in the compositions of the invention may be in a range of from 0.1 to 30 weight ％, preferably 1 to 20 weight ％, and more preferably 5 to 15 weight ％, based on the weight of the total composition.

Compositions of the invention 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. 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.

The personal care composition of the invention may also include, for instance, a thickener, additional emollients, an emulsifier, a humectant, a surfactant, a suspending agent, a film forming agent, a lower monoalcoholic polyol, a high boiling point solvent, a propellant, a mineral oil, silicon feel modifiers, or mixtures thereof. The amount of optional ingredients effective for achieving the desired property provided by such ingredients can be readily determined by one skilled in the art.

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, colorants, 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, and vitamins (e.g., Vitamin C) and derivatives thereof. 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.

As noted above, personal care compositions of the present invention are highly effective as skin lightening agents. They exhibit skin lightening attributes on par with, if not better than previously known compositions for personal care applications, without the disadvantage of a short timeframe of effectiveness after application. Thus, in one aspect the present invention provides that the personal care compositions may be used in a method for lightening skin tone. In another aspect, the present invention provides a method for improving the visible light scattering of a composition by adding the voided latex particles to a composition comprising at least one pigment grade inorganic metal oxide particle. In practicing the methods of the invention, the personal 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 skin lightening that an individual is likely to desire. 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 Titanium Dioxide Coated PCL-PU Microparticles

Exemplary titanium dioxide coated PCL-PU microparticles of the present invention were prepared in three phases: pre-polymer preparation； preparation of the PCL-PU microparticle suspension； and coating of the PCL-PU microparticle with titanium dioxide via spray drying.

Pre-Polymer Preparation

108 g of PTMEG 2000 (poly (tetramethylene ether) glycol) from Sigma-Aldrich and 12 g of PCL 1000 from Polysciences, Inc. was heated at 120℃ for 1 hour and then cooled to 50℃. The pre-polymer stock solution was obtained by adding 45 g of IPDI (isophorone diisocyanate) from Sigma-Aldrich to the PTMEG/PCL solution and heating at 94℃ for 3.5 hours. The system was purged under N₂ throughout the reaction process. The NCO value of the pre-polymer stock solution was 2 to 8 weight ％as measured by titration.

Preparation of Polycaprolactone-Polyurethane Microparticle Suspension

60 g of the pre-polymer solution was added to 240 g of PVA 2088 (polyvinyl alcohol) available from Sigma-Aldrich in 7 weight ％solution at 4℃ dropwise under high speed stirring at 2,000 rpm. The solution was stirred for an additional 30 minutes after addition of the pre-polymer solution to the PVA. DETA aqueous (25 weight ％, 1.1x molar ratio to NCO groups in pre-polymer solution) was introduced into the suspension and continuously stirred for 40 minutes. The obtained suspension was washed and centrifuged to collect a polyurethane slurry.

Coating of the Polycaprolactone-Polyurethane Microparticle with Zinc Pyrithione

A 20％titanium dioxide (TiO₂) suspension was obtained by adding 20 g TiO₂ (R706 (TiO₂ 100-300 nm) available from DuPont) was added to 80 g water and mixed by a high speed shearing under 2,000 rpm for 30 mins. The TiO₂ suspension was then mixed with the PCL-PU slurry in four different weight ratios of TiO₂ particles to PCL-PU microparticles: 0.5: 9.5； 1.0: 9.0； 1.5: 8.5； and 2.0: 8.0. Each mixture was then diluted with water to create a 50x diluted composite particle dilution. Each dilution was then spray dried (air inlet temp ＝ 130℃； air speed ＝ 40； flow rate ＝ 10 ml/min) to obtain the titanium dioxide coated PCL-PU microparticles.

Example 2

Morphology Characterization of Exemplary TiO₂ Coated PCL-PU Microparticles

The particle morphology of PCL-PU particles (from the PCL-PU slurry) and the four batches of titanium dioxide coated PCL-PU microparticles as prepared in Example 1 above was evaluated by scanning electron microscopy (SEM) using an FEI Nova^TM Nano SEM630. The images in FIG. 1 indicate a “raspberry-like” morphology of the TiO₂ PCL-PU microparticles. FIG. 1 (a) illustrates unaltered PCL-PU microparticles having an average particle size of from 1 to 40 microns. FIGs. 1 (b) - (d) further illustrate an increase in the amount of TiO₂ particles coated onto the PCL-PU microparticle surface as the ratio of TiO₂/PCL-PU increases. FIG. 1 (e) further illustrates that a max loading of TiO₂ once the weight ratio of TiO₂ to PCL-PU microparticles is raised to 2: 8.

Example 3

Surface Analysis of Titanium Dioxide Coated PCL-PU Microparticles

The composition of the surface of the TiO₂ PCL-PU (10: 90) microparticles as prepared in Example 1 above was analyzed via energy-dispersive X-ray spectroscopy (EDX) . The EDX elemental analysis shown in FIG. 2 demonstrates that Ti elemental peaks were observed from the particles. Color highlighted elements signal by mapping technology indicated that the elemental response came from the surface of the microparticle, confirming that the TiO₂ coated PCL-PU microparticles prepared substantially in accordance with Example 1 were hybrid microparticles of PCL-PU coated with TiO₂.

Example 4

Preparation of Exemplary and Comparative Skin Lightening Compositions

Exemplary and comparative skin lightening compositions of the present invention contain a base formulation containing the components recited in Table 1.

Table 1. Base Formulation for Skin Lightening Compositions

¹Available from Lubrizol

²Available from Protameen Chemicals

³Available from Rita Corporation

⁴Available from Guangzhou Yiming

⁵Available from The Dow Chemical Company

⁶Available from ANGUS Chemical Company

⁷Available from Ashland

Deionized water and 1, 3-butanediol were added into a first vessel and stirred at 400 rpm while slowly adding

Ultrez 10 with continued mixing until homogeneity was achieved.

The mixture was them raised to a temperature of about 80℃. In a second vessel, Procol CS-20D, Rita GMS, isopropyl myristate, and GREOIL GTCC were combined and heated to a temperature of about 80℃. The contents of the second vessel were then added slowly to the contents of the first vessel and stirred for 10 minutes at 4,000 rpm. Stirring was then slowed to 300 rpm while the mixture was cooled to 40℃. Once the mixture reached 40℃, TRIS AMINO^TM Ultra PC and Optiphen^TM were added to adjust the pH to the relevant target. BD-4039 was then added with continued mixing until homogeneity was achieved, at which point mixing was stopped and the mixture was cooled to room temperature.

Exemplary and comparative skin lightening formulations were then prepared using the base formulation and contain the components recited in Table 2.

Table 2. Exemplary and Comparative Skin Lightening Compositions

To make 200 g of the composition, 190 g of base formulation as prepared above were placed into a 250 ml vessel. The relevant amount of powder or water was slowly added to the vessel while and stirred at 400 rpm for 15-20 minutes. The mixture was then mixed for an additional 15 minutes at 10,000 rpm.

Example 5

Evaluation of Lightness of Films Cast from Exemplary and Comparative Compositions

Films prepared from exemplary and comparative skin lightening compositions as prepared in Example 4 above were evaluated for lightness which is related to the skin whitening effect in skin care application. The film was prepared on a Black-White drawdown card with Sheen. The wet film was dried in the air at 23℃, 54％relative humidity for 24 hours before measurement. Then the film lightness (L*) was evaluated using a Konica CA 2600 spectrophotometer set to color system L*a*b*, 3 light source set to D65, and an angle selection of 10 degrees. The results of the lightness evaluation are reported in Table 3.

Table 3. Lightness of Exemplary and Comparative Formulations

	E1	E2	Blank	C1	C2	C3
L^*	36.21	30.48	8.24	15.4	28.18	29.53

The above results demonstrate that the inventive examples containing PCL-PU microparticles coated with TiO₂ (E1 and E2) demonstrate the higher lightness when compared against examples containing only PU-PCL microparticles (C1) , only TiO₂ (C2) , and TiO₂ plus PLC-PU microparticles (C3) .

Example 6

Evaluation of Blurring Effect of Films Cast from Exemplary and Comparative Compositions

Films prepared from exemplary and comparative skin lightening compositions as prepared in Example 5 above were evaluated for blurring effect. FIG. 3 shows images of forward diffuse light of a 3 mv laser point going through the dry films. The distance between the film and the screens was 50 cm, and the distance between the laser point and film was 10 cm. The white spot at the center of each image indicates that irradiant light is able to travel directly through the film, i.e., that there is little or no diffusion of light. The larger the white spot at the center of each image, the weaker the blurring effect. Based upon this criteria, a performance ranking of + (indicating very little blurring) to ++++ (indicating a high amount of blurring) was assigned to each sample film. The ranking assigned for each sample film is reported in Table 4.

Table 4. Blurring Effect of Exemplary and Comparative Formulations

	E1	E2	Blank	C1	C2	C3
Blurring	++++	+++	--	+++	+	+++

The above results demonstrate that inventive compositions containing PCL-PU microparticles coated with TiO₂ provide a blurring effect that is at least as good (E2) if not better (E1) than comparative examples containing only PU-PCL microparticles (C1) , only TiO₂ (C2) , and TiO₂ plus PLC-PU microparticles (C3) .

Example 7

Evaluation of Smoothness of Exemplary and Comparative Compositions

Exemplary compositions E1 and E2 and comparative compositions C2 and C3 as prepared in Example 4 above were evaluated for cream smoothness by measuring the cream normal force under shearing. A TA Instruments AR2000EX rheometer was used with the equilibrium being set at 25℃ to 2 minutes as a conditioning step, a continuous ramp step having a shear rate of 0.1 s^-1 to 10,000 s^-1, and a duration of 30 minutes at 5 points per decade. The higher the cream normal force, the smoother the cream. The results of the cream smoothness evaluation are reported in Table 5.

Table 5. Smoothness of Exemplary and Comparative Compositions

The above results demonstrate that inventive compositions containing PCL-PU microparticles coated with TiO₂ (E1 and E2) provide significantly better smoothness when compared against examples containing only TiO₂ (C2) and TiO₂ plus PLC-PU microparticles (C3) .

Claims

A composition comprising polycaprolactone-polyurethane microparticles coated with inorganic metal oxide particles, wherein the weight ratio of inorganic metal oxide particles to the polycaprolactone-polyurethane microparticles is in a range of from 5: 95 to 2: 8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns.
The composition of claim 1, wherein the polycaprolactone-polyurethane microparticles have an average particle size of 1 to 40 microns.
The composition of claim 1, wherein the polycaprolactone-polyurethane microparticles have an average particle size of 5 to 30 microns.
The composition of claim 1, wherein the inorganic metal oxide particles comprise titanium dioxide.
The composition of claim 4, wherein the titanium dioxide particles have an average particle size of 100 to 300 nm.
The composition of claim 1, wherein the weight ratio of inorganic metal oxide particles to the polycaprolactone-polyurethane microparticle is in a range of from 1: 9 to 15: 85.
A process for preparing a polycaprolactone-polyurethane microparticle coated with inorganic metal oxide particles comprising the steps of:

(a) mixing a pre-polymer reaction mixture comprising an isocyanate, a polyol, and polycaprolactone to provide a polycaprolactone-polyurethane pre-polymer；

(b) reacting the polyurethane pre-polymer mixture in the presence of an amine catalyst and a polyvinyl alcohol to provide a polycaprolactone-polyurethane slurry containing polycaprolactone-polyurethane microparticles having an average particle size of 0.1 to 50 microns；

(c) mixing the polyurethane slurry with an inorganic metal oxide suspension to provide a polycaprolactone-polyurethane/inorganic metal oxide composite dilution； and

(d) spray drying the polycaprolactone-polyurethane/inorganic metal oxide composite dilution to provide an inorganic metal oxide coated polycaprolactone-polyurethane microparticle.
The method of claim 7, wherein

(i) the isocyanate is selected from the group consisting of toluene diisocyanate, methylene diisocyanate, isophorone diisocyanate, cyclohexane-1, 3-diisocyanate, cyclohexane-1, 4-diisocyanate, hexamethylene diisocyanate, m-tetramethyloxylene diisocyanate, 2, 2, 4-trimethyl hexamethylene diioscyanate, 2, 4, 4-trimethyl hexamethylene diioscyanate, 2, 5-norbornane diisocyanate, m-xylene diisocyanate, bis- (cyclohexyl isocyanate) methane, and combinations thereof,

(ii) the polyol is selected from the group consisting of ethylene glycol, diethylene glycol, 1, 4-butane diol, poly (tetramethylene ether glycol) , polyoxypropylene glycol, polyether triol, polyether tetrol, and combinations thereof,

(iii) the amine catalyst is selected from the group consisting of ethylenediamine (EDA) , triethylenetetramine (TETA) , isophoronediamine (IDPA) , diethylenetriamine (DETA) , N, N- dimethylcyclohexylamine, N, N-dimethylcetylamine, diamino-bicyclooctane, and combinations thereof, and

(iv) the inorganic metal oxide particle comprises pigment grade titanium dioxide having an average particle size of from 100 to 300 nm.
A method for lightening skin tone comprising topically administering to the skin an effective amount of a personal care composition comprising polycaprolactone-polyurethane microparticles coated with pigment grade inorganic metal oxide particles, wherein the weight ratio of pigment grade inorganic metal oxide particles to the polycaprolactone-polyurethane microparticles is in a range of from 5: 95 to 2: 8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns.
A method for improving visible light scattering of a composition comprising adding to said composition from 0.1 to 30 weight ％ of polycaprolactone-polyurethane microparticles coated with pigment grade inorganic metal oxide particles, based on the total weight of the composition, wherein the wherein the weight ratio of pigment grade inorganic metal oxide particles to the polycaprolactone-polyurethane microparticles is in a range of from 5: 95 to 2: 8, and the polycaprolactone-polyurethane microparticles have an average particle size of 0.1 to 50 microns.