WO2017104587A2

WO2017104587A2 - Composite particle

Info

Publication number: WO2017104587A2
Application number: PCT/JP2016/086834
Authority: WO
Inventors: Shinichi Matsufuji
Original assignee: L'oreal
Priority date: 2015-12-14
Filing date: 2016-12-06
Publication date: 2017-06-22
Also published as: WO2017104587A3; JP2017109928A

Abstract

The present invention relates to a composite particle according to the present invention comprises (a) at least one core particle, wherein the (a) core particle is at least in part covered with at least one first coating layer comprising (b) at least one solid UV filter, and the first coating layer is at least in part covered with at least one second coating layer comprising (c) at least one hydrophobic block copolymer, as well as a cosmetic composition including the composite particle. The composite particle according to the present invention can maintain enhanced UV protection performance even in the presence of specific anionic surfactants, and the composition according to the present invention can maintain enhanced UV protection even due to washing with water.

Description

DESCRIPTION

COMPOSITE PARTICLE

TECHNICAL FIELD

The present invention relates to a composite particle comprising a core particle which has at least one first coating layer comprising at least one solid UV filter and at least one second coating layer comprising at least one hydrophobic block copolymer, as well as a composition, preferably a cosmetic composition including the composite particle, a method for preparing the composite particle, and the like.

BACKGROUND ART Many cosmetics include one or more UV filters in order to shield UV rays. In particular, skin cosmetics commonly include inorganic solid UV filters such as fine particles of Ti0₂ for protecting the skin from UV rays.

WO 2012/105060 and WO 2012/105723 disclose a composite pigment comprising a small core particle which is coated with inorganic solid UV filters and or coloring pigments.

WO 2014/010101 discloses a composite pigment comprising a small hollow core particle which is coated with inorganic solid UV filters. The above composite pigments can provide enhanced UV protection performance in comparison with a simple powder of inorganic solid UV filters such as Ti0₂ fine particles. Thus, a cosmetic composition including the above composite pigment can provide enhanced UV protection as compared with a composition including the simple powder of inorganic solid.UV filters.

DISCLOSURE OF INVENTION

However, it has been observed that the above composite pigment may lose the enhanced UV protection performance in the presence of a few specific anionic surfactants, and that a cosmetic composition including the above composite pigment may lose the enhanced UV protection when being washed with water.

An objective of the present invention is to provide a composite particle which includes at least one core particle coated with at least one solid UV filter while the composite particle does not lose enhanced UV protection performance in the presence of specific anionic surfactants, as well as a cosmetic composition which includes the composite particle while the composition does not lose enhanced UV protection even when being washed with water.

The above objective can be achieved by a composite particle, comprising:

(a) at least one core particle,

wherein

the (a) core particle is at least in part covered with at least one first coating layer comprising (b) at least one solid UV filter, and

the first coating layer is at least in part covered with at least one second coating layer comprising (c) at least one hydrophobic block copolymer. The mean particle size of the (a) core particle may be 100 nm or more, preferably 200 nm or more, and more preferably 300 nm or more, and/or 50 um or less, preferably 20 um or less, and more preferably 10 um or less. The (a) core particle may comprise at least one inorganic material and/or at least one organic material, preferably at least one organic material.

The (b) solid UV filter may be selected from inorganic solid UV filters, preferably is selected from the group consisting of silicon carbide, metal oxides, and mixtures thereof, and more preferably is titanium oxide.

The (b) solid UV filter may have a mean particle size of from 1 nm to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to 50 nm. The weight ratio of the (a) core particle(s) to the (b) solid UV filter(s) may be from 10:90 to 90: 10, preferably from 20:80 to 80:20, and more preferably from 30:70 to 70:30.

The (c) hydrophobic block copolymer may have a recovery ratio of 50% or more, preferably 60% or more, and more preferably 70% or more.

The (c) hydrophobic block copolymer may be a hydrocarbon-based block copolymer, preferably comprising at least one styrene block and at least one block comprising units chosen from butadiene, ethylene, propylene, butylene, and isoprene or a mixture thereof, which are optionally hydrogenated. The (c) hydrophobic block copolymer may be chosen from styrene-ethylene/propylene, styrene- ethylene/butadiene, slyrene-ethylene/butylene, styrene-ethylene/isoprene diblock copolymers which are optionally hydrogenated, and styrene-ethylene/propylene-styrene, styrene-ethylene/butadiene- styrene, styrene-ethylene/butylehe-styrene, styrene-isoprene-styrene, and styrene-butadiene-styrene triblock copolymers, which are optionally hydrogenated, and mixtures thereof.

The weight ratio of the (a) core particle(s) to the (c) hydrophobic block copolymer(s) may be from 50:50 to 99: 1, preferably from 60:40 to 95:5, and more preferably from 70:30 to 90: 10.

The amount of the second coating layer may be from 0.01 to 30% by weight, preferably from 0.1 to 20% by weight, and more preferably from 0.3 to 15% by weight, relative to the total weight of the composite particle.

The above objective can also be achieved by a composition, preferably a cosmetic composition comprising the composite particle according to the present invention.

The present invention also relates to a cosmetic use of a composite particle according to the present invention.

The present invention also relates to a process, preferably a cosmetic process comprising

applying a composite particle according to the present invention, or a cosmetic composition according to the present invention onto a keratin substance.

The present invention also relates to a method for preparing a composite particle, comprising a step of subjecting:

(a) at least one core particle; (b) at least one solid UV filter; and

(c) at least one hydrophobic block copolymer

to a mechanochemical fusion process. BEST MODE FOR CARRYING OUT THE INVENTION

After diligent research, the inventor has discovered that it is possible to provide a composite particle which includes at least one core particle coated with at least one solid UV filter while the composite particle does not lose enhanced UV protection performance in the presence of specific anionic surfactants, as well as a cosmetic composition which includes the composite particle while the composition does not lose enhanced UV protection even when being washed with water.

Thus, the composite particle according to the present invention comprises

(a) at least one core particle,

wherein

the first coating layer is at least in part covered with at least one second coating layer comprising (c) at least one hydrophobic block copolymer.

The composition according to the present invention comprises the above composite particle.

The composite particle according to the present invention can maintain enhanced UV protection performance even in the presence of the specific anionic surfactants, and the cosmetic composition according to the present invention can maintain enhanced UV protection even when being washed with water.

Hereafter, the composite particle and the composition according to the present invention, and the like, will be described in a detailed manner.

[Composite Particle]

The composite particle according to the present invention comprises (a) at least one core particle which is at least in part covered with at least one first coating layer comprising (b) at least one solid UV filter, and the first coating layer is at least in part covered with at least one second coating layer comprising (c) at least one hydrophobic block copolymer. The (a) core particle, (b) solid UV filter, and (c) hydrophobic block copolymer will be explained below.

{Core Particle}

The composite particle according to the present invention comprises at least one (a) core particle. If two or more (a) core particles are used, they may be the same or different.

The (a) core particle to be used for the composite particle according to the present invention is not limited as long as it can be at least in part coated with the above first and second coating layers.

It is preferable that mean particle size of the (a) core particle be 100 nm or more, preferably 200 nm or more, and more preferably 300 nm or more, and/or 50 um or less, preferably 20 um or less, and more preferably 10 um or less. Unless otherwise defined, the mean particle size or mean particle diameter is an arithmetic mean diameter, and can be determined, for example, by calculating the average of the dimensions of one hundred particles chosen on an image obtained with a scanning electron microscope. The (a) core particle can be in any shape.

For example, the (a) core particle may be a concave particle having at least one concavity, and preferably in a general concave shape. The concavity is not a small dimple or pit, but a large hollow or crater which preferably includes a geometrical center or a center of gravity of the particle. Preferably, the (a) core particle defines an inner concave surface and an outer convex surface which is opposite to the inner concave surface. In particular, the (a) core particle is preferably in the form of a portion of a hollow sphere or a bowl. The (a) core particle may have a transverse cross section with the shape of a horseshoe or arch. On the other hand, it is possible to use a core particle in the form of a plate with an aspect ratio of at least 5, preferably more than 10, more preferably more than 20, and more preferably more than 50. The aspect ratio can be determined by the average thickness and the average length according to the formula: aspect ratio = length/thickness. If a plate-like particle is used for the present invention, it is preferable that the plate-like particle have a (longest) length of 100 nm or more, preferably 200 nm or more, and more preferably 300 nm or more, and/or 30 um or less, preferably 20 um or less, and more preferably 10 um or less.

In a preferred embodiment, the (a) core particle has a spherical shape.

The (a) core particle can be solid or hollow.

The material of the (a) core particle is not limited. The material of the (a) core particle may comprise at least one inorganic material and/or at least one organic material. It may be preferable that the (a) core particle comprise at least one organic material.

The inorganic material and/or organic material may be hollow or porous. The porosity of the material may be characterized by a specific surface area of from 0.05 m²/g to 1,500 m²/g, more preferably from

2 2 2 2

0.1 mVg to 1,000 m g, and even more preferably from 0.2 m /g to 500 m /g according to the BET method. However, it is preferable to use solid inorganic material(s) and/or solid organic material(s), preferably 'not hollow' materials.

Preferably, the organic material can be selected from the group consisting of (co)poly(meth)acrylates, (co)polyamides, silicones (in particular silicone resins), (co)polyurethanes, (co)polyethylenes, (co)polypropylenes, (co)polystyrenes,(co) polyhydroxyalkanoates, (co)polycaprolactams,

(co)poly(butylene) succinates, (co)polysaccharides, (co)polypeptides, (co)polyvinyl alcohols, (co)polyvinyl resins, fluoro(co)polymers, (co)polyester, (co)polylactic acid, waxes, amidosulfonic acid polyvalent metal salts, acylated amino acids, and mixtures thereof. In particular, as the organic material, copolystyrene may be preferable, and styrene/acrylate copolymer, and cross-linked styrene/methyl methacrylate copolymer may be more preferable. Thus, as the (a) core particles, for example, Sunspheres (small hollow particles made from styrene/acrylate copolymer) marketed by Rohm and Haas, as well as SX859(A) and SX866(B) (small hollow particles made form cross-linked styrene/ methyl methacrylate copolymer) marketed by JSR Corp. in Japan may be preferable. Polymethylmethacrylate particles such as MP-2200, MP-2701 and MP-1451 and methylmethacrylate crosspolymer such as MR-7GC marketed by Soken in Japan may also be preferable as the organic material.

(Co)polyamides such as Nylon®, polyhydroxyalkanoates such as polylactic acids, (co)polyurethanes, silicones and mixtures thereof may also be preferable. As the (co)polyamide particles, SP-500 marketed by Toray and Orgasol marketed by Arkema may be more preferable. As the (co) polyurethane particles, D-400 marketed by Toshiki Pigment may be more preferable. As the silicones, silicone resins (in particular polymethylsilsesquioxane) such as Tospearl marketed by Momentive Performance Material may be more preferable as the organic material.

As fluoro(co)polymers, for example, PTFE may be used. As amidosulfonic acid polyvalent metal salts, for example, N-lauroyltaurine calcium may be used. As acylated amino acids, lauroyllysine may be used. As polysaccharide, mention may be made of starches, cellulose and its derivatives, and mixtures thereof. Cellulose and its derivatives are preferable. The cellulose and its derivatives may be porous or non-porous. However, it is preferable that the cellulose and its derivatives be porous. According to one embodiment, a cellulose derivative may be chosen from cellulose esters and ethers. The term "cellulose ester" means, in the text hereinabove and hereinbelow, a polymer consisting of an a (1-4) sequence of partially or totally esterified anhydroglucose rings, the esterification being obtained by reaction of all or only some of the free hydroxyl functions of the said anhydroglucose rings with a linear or branched carboxylic acid or carboxylic acid derivative (acid chloride or acid anhydride) containing from 1 to 4 carbon atoms. Preferably, the cellulose ester results from the reaction of some of the free hydroxyl functions of the said rings with a carboxylic acid containing from 1 to 4 carbon atoms. Advantageously, the cellulose esters are chosen from cellulose acetates, propionates, butyrates, isobutyrates, acetobutyrates and acetopropionates, and mixtures thereof.

The term "cellulose ether" means a polymer consisting of an a (1-4) sequence of partially etherified anhydroglucose rings, some of the free hydroxyl functions of the said rings being substituted with a radical -OR, R preferably being a linear or branched alkyl radical containing from 1 to 4 carbon atoms. The cellulose ethers are thus preferably chosen from cellulose alkyl ethers with an alkyl group containing from 1 to 4 carbon atoms, such as cellulose methyl, propyl, isopropyl, butyl and isobutyl ethers.

As the core particle comprising cellulose and its derivative, mention may be made of the following cellulose particles:

Cellulobeads USF (porous cellulose), Cellulobeads D-5, Cellulobeads D-10, MOISCELL PW D-5 XP (potassium succinate cellulose), and MOISCELL PW D-50 XP (potassium succinate cellulose), marketed by Daito Kasei;

CELFLOW C-25 (cellulose), CELFLOW T-25 (cellulose acetate), CELFLOW TA-25 Cellulose acetate, marketed by Chisso;

MICROPEARL CB-10 (cellulose) marketed by Matsumoto Yushi;

Avicel PH 105 (rmcrocrystalline cellulose) marketed by FMC corporation,

Ceolus PH-101 (microcrystalline cellulose), Ceolus PH-F20JP (microcrystalline cellulose), CEOLUS RC-A591NF (microcrystalline cellulose/cellulose gum) marketed by Asahi Kasei;

ETHOCEL standard 100 premium (ethyl cellulose) marketed by DOW Chemical.

As polylactic acids, for example, Ecosoft 608XF, and Ecosoft 611 (marketed by Micro Powder) may be used. Preferably, the inorganic material can be selected from the group consisting of mica, synthetic mica, talc, sericite, boron nitride, glass flakes, calcium carbonate, barium sulfate, titanium oxide,

hydroxyapatite, silica, silicate, zinc oxide, magnesium sulfate, magnesium carbonate, magnesium trisilicate, duminum oxide, duminum silicate, calcium silicate, calcium phosphate, magnesium oxide, bismuth oxychloride, kaolin, hydrotalcite, mineral clay, synthetic clay, iron oxide, and mixtures thereof. In particular, natural mica, synthetic mica, sericite, kaolin, talc, silica, and mixtures thereof are preferable. In particular, silica particles such as Cosmo 30, Satinier M16 and BA-1 marketed by JGC C&C and Sunsphere H33 marketed by AGC SI-TECH may be preferable.

The (a) core particle may or may not be coated beforehand. In a particular embodiment, the (a) core particle may be originally coated. The material of an original coating of the (a) core particle is not limited, but an organic material such as an amino acid, an N- acylamino acid, an amido, a silicone, and a modified silicone, may be preferable. As the organic material, mention may be made of lauroyl lysine and acryl-modified silicone. It may be preferable to use a combination of at least one small core particle and at least one large core particle.

The mean particle size or mean particle diameter of the small core particle may be more than 100 nm and less than 1 um, preferably less than 800 nm, and more preferably less than 600 nm.

The mean particle size or mean particle diameter of the large core particle may be 2 um or more, preferably 3 um or more, more preferably 4 um or more, and even more preferably 5 um or more. The mean particle size of the large core particle may be limited to 30 um or less, preferably 20 um or less, and more preferably 10 um or less.

The material of the small and large core particles can be selected independently. As the material, the organic and inorganic materials explained above can be used.

In the composite particle according to the present invention, the weight ratio of the small core particle(s) to the large core particle(s) may be 10:90 to 90: 10, preferably 20:80 to 80:20, and more preferably 30:70 to 70:30.

In a preferred embodiment, the composite particle according to the present invention may satisfy the following requirements:

the small core particle comprises at least one copolystyrene, preferably styrene/acrylate copolymer, and/or silica; and

the large core particle comprises at least one poly(meth)acrylate, preferably methyl methacrylate polymer, and/or silicone resin. The (a) core particle may be present in the composite particle in a content ranging from 45 to 90% by weight, preferably ranging from 40 to 80% by weight, and more preferably from 35 to 70% by weight, relative to the total weight of the composite particle.

{Solid UV Filter} The first coating layer of the composite particle according to the present invention comprises at least one (b) solid UV filter. If two or more (b) solid UV filters are used, they may be the same or different.

The (b) solid UV filter may be present in the composite particle in a content ranging from 1 to 50% by weight, preferably ranging from 4 to 40% by weight, and more preferably from 8 to 35% by weight, relative to the total weight of the composite particle.

(Inorganic Solid UV Filter) The (b) solid UV filter(s) in the first coating layer(s) on the (a) core particle may be inorganic solid UV filter(s). If two or more inorganic solid UV filters are used, they may be the same or different, preferably the same. The inorganic solid UV filter may be hydrophilic and/or lipophilic. The inorganic solid UV filter is properly insoluble in solvents such as water and ethanol commonly used in cosmetics. The term "solid" means solid at 25°C under 1 atm.

It is preferable that the inorganic solid UV filter is in the form of a medium size fine particle such that the mean (primary) particle diameter thereof ranges from 1 ran to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to 50 nm. The mean (primary) particle size or mean (primary) particle diameter here is an arithmetic mean diameter.

The inorganic solid UV filter may comprise at least one inorganic compound selected from the group consisting of silicon carbide, metal oxides which may or may not be coated, and mixtures thereof.

Preferably, the inorganic solid UV filters are selected from pigments (mean size of the primary particles: generally from 1 nm to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to 50 nm) formed of metal oxides, such as, for example, pigments formed of titanium oxide (amorphous or crystalline in the rutile and/or anatase form), iron oxide, zinc oxide, zirconium oxide or cerium oxide, which are all well-known UV photoprotective agents per se. The inorganic solid UV filter may or may not be coated. The inorganic solid UV filter may have at least one coating. The coating may comprise at least one compound selected from the group consisting of alumina, silica, aluminum hydroxide, silicones, silanes, fatty acids or salts thereof (such as sodium, potassium, zinc, iron or aluminum salts), fatty alcohols, lecithin, amino acids,

polysaccharides, proteins, alkanolamines, waxes such as beeswax, (meth)acrylic polymers, organic UV filters, and (per)fluoro compounds.

The coated inorganic solid UV filters may be titanium oxides coated:

with silica, such as the product "Sunveil" from Ikeda;

with silica and with iron oxide, such as the product "Sunveil F" from Ikeda;

with silica and with alumina, such as the products "Microtitanium Dioxide MT 500 SA" from Tayca, "Tioveil" from Tioxide, and "Mirasun TiW 60" from Rhodia

with alumina, such as the products "Tipaque TTO-55 (B)" and "Tipaque TTO-55 (A)" from Ishihara, and "UVT 14/4" from Kernira;

with alumina and with aluminum stearate, such as the product "Microtitanium Dioxide MT 100 T, MT 100 TX, MT 100 Z, or MT-01 " from Tayca, the products "Solaveil CT-10 W" and "Solaveil CT 100" from Uniqema, and the product "Eusolex T-AVO" from Merck;

with alumina and with aluminum laurate, such as the product "Microtitanium Dioxide MT 100 S" from Tayca;

with iron oxide and with iron stearate, such as the product "Microtitanium Dioxide MT 100 F" from Tayca; with zinc oxide and with zinc stearate, such as the product "BR351 " from Tayca;

with silica and with alumina and treated with a silicone, such as the products "Microtitanium Dioxide MT 600 SAS", "Microtitanium Dioxide MT 500 SAS" and "Microtitanium Dioxide MT 100 SAS" from Tayca;

with silica, with alumina, and with aluminum stearate and treated with a silicone, such as the product "STT-30-DS" from Titan Kogyo;

with silica and treated with a silicone, such as the product "UV-Titan X 195" from Kemira;

with alumina and treated with a silicone, such as the products "Tipaque TTO-55 (S)" from Ishihara or "UV Titan M 262" from Kemira

with triemanolamine, such as the product " STT-65-S " from Titan Kogyo;

with stearic acid, such as the product "Tipaque TTO-55 (C)" from Ishihara; or

with sodium hexametaphosphate, such as the product "Microtitanium Dioxide MT 150 W" from

Tayca. Other titanium oxide pigments treated with a silicone are preferably Ti0 treated with

octyltrimethylsilane and for which the mean size of the individual particles is from 25 and 40 nm, such as that marketed under the trademark "T 805" by Degussa Silices, Ti0₂ treated with a

polydimethylsiloxane and for which the mean size of the individual particles is 21 nm, such as that marketed under the trademark "70250 Cardre UF Ti0₂Si₃" by Cardre, anatase/rutile Ti0₂ treated with a polydimethylhydrosiloxane and for which the mean size of the individual particles is 25 nm, such as that marketed under the trademark "Microtitanium Dioxide USP Grade Hydrophobic" by Color Techniques.

Preferably, the following coated Ti0₂ may be used as the coated inorganic UV filter:

Stearic acid (and) Aluminum Hydroxide (and) Ti0₂, such as the product "MT-100 TV" from Tayca, with a mean primary particle diameter of 15 nm;

Dimethicone (and) Stearic Acid (and) Aluminum Hydroxide (and) TiO_¾ such as the product "SA- TTO-S4" from Miyoshi Kasei, with a mean primary particle diameter of 15 nm;

Silica (and) Ti0₂, such as the product "MT-100 WP" from Tayca, with a mean primary particle diameter of 15 nm;

Dimethicone (and) Silica (and) Aluminum Hydroxide (and) Ti0₂, such as the product "MT-Y02" and "MT-Y-110 M3S" from Tayca, with a mean primary particle diameter of 10 nm;

Dimethicone (and) Aluminum Hydroxide (and) Ti0₂, such as the product "SA-TTO-S3" from

Miyoshi Kasei, with a mean primary particle diameter of 15 nm;

Dimethicone (and) Alumina (and) Ti0₂, such as the product "UV TITAN M170" from Sachtleben, with a mean primary particle diameter of 15 nm; and

Silica (and) Aluminum Hydroxide (and) Alginic Acid (and) Ti0₂, such as the product "MT-100 AQ" from Tayca, with a mean primary particle diameter of 15 nm. In terms of UV filtering ability, Ti0₂ coated with at least one organic UV filter may be more preferable. As the organic UV filter, a dibenzoylmethane derivative such as butyl methoxydibenzoylmethane (Avobenzone) and 2,2'-Memylenebis[6-(2H-BenzotriazoL^^

(Methylene Bis-Benzotriazolyl Tetramethylbutylphenol) marketed as "TP OSORB" M by BASF may be preferable. Thus, for example, Avobenzone (and) Stearic Acid (and) Aluminum Hydroxide (and) Ti0₂, such as the product "HXMT-IOOZA" from Tayca, with a mean primary particle diameter of 15 nm, may preferably be used.

The uncoated titanium oxide pigments are, for example, those marketed by Tayca under the trademarks "Microtitanium Dioxide MT500B" or "Microtitanium Dioxide MT600B", by Degussa under the trademark "P 25", by Wacker under the trademark "Oxyde de titane transparent PW", by Miyoshi Kasei under the trademark "UFTR", by Tomen under the trademark "ITS", and by Tioxide under the trademark "Tioveil AQ".

The uncoated zinc oxide pigments are, for example:

those marketed under the trademark "Z-cote" by Sunsmart;

those marketed under the trademark "Nanox" by Elementis; and

those marketed under the trademark "Nanogard WCD 2025" by Nanophase Technologies.

The coated zinc oxide pigments are, for example:

those marketed under the trademark "Oxide Zinc CS-5" by Toshiba (ZnO coated with

polymethylhydrosiloxane);

those marketed under the trademark "Nanogard Zinc Oxide FN" by Nanophase Technologies (as a 40% dispersion in Finsolv TN, ₂-Ci₅ alkyl benzoate);

those marketed under the trademark "Daitopersion Zn-30" and "Daitopersion Zn-50" by Daito (dispersions in oxyethylenated polya¾iethylsiloxane/cyclopolymethylsiloxane comprising 30% or

50% of zinc nano-oxides coated with silica and polymethylhydrosiloxane);

those marketed under the trademark "NFD Ultrafine ZnO" by Daikin (ZnO coated with phosphate of perfluoroalkyl and a copolymer based on perfluoroalkylethyl as a dispersion in cyclopentasiloxane); those marketed under the trademark "SPD-Z1 " by Shin-Etsu (ZnO coated with a silicone-grafted acrylic polymer dispersed in cyclodimethylsiloxane);

those marketed under the trademark "Escalol Z100" by ISP (alurnina-treated ZnO dispersed in an ethylhexyl methoxycinnamate/PVP-hexadecene copolymer/methicone mixture); those marketed under the trademark "Fuji ZnO-SMS-10" by Fuji Pigment (ZnO coated with silica and

polymethylsilsesquioxane); and

those marketed under the trademark "Nanox Gel TN" by Elementis (ZnO dispersed at 55% in C₁₂-C₁₅ alkyl benzoate with hydroxystearic acid polycondensate).

The uncoated cerium oxide pigments are marketed, for example, under the trademark "Colloidal Cerium Oxide" by Rhone-Poulenc.

The uncoated iron oxide pigments are, for example, marketed by Arnaud under the trademarks "Nanogard WCD 2002 (FE 45B)", "Nanogard Iron FE 45 BL AQ", "Nanogard FE 45R AQ", and "Nanogard WCD 2006 (FE 45R)", or by Mitsubishi under the trademark "TY-220". The coated iron oxide pigments are, for example, marketed by Arnaud under the trademarks

"Nanogard WCD 2008 (FE 45B FN)", "Nanogard WCD 2009 (FE 45B 556)", "Nanogard FE 45 BL 345", and "Nanogard FE 45 BL" or by BASF under the trademark "Oxyde de fer transparent".

Mention may also be made of mixtures of metal oxides, in particular of titanium dioxide and of cerium dioxide, including a mixture of equal weights of titanium dioxide coated with silica and of cerium dioxide coated with silica marketed by Ikeda under the trademark "Sunveil A", and also a mixture of titanium dioxide and of zinc dioxide coated with alumina, with silica, and with silicone, such as the product "M 261" marketed by Kemira, or coated with alumina, with silica and with glycerol, such as the product "M 211 " marketed by Kemira.

It may be preferable for the coating(s) of the inorganic solid UV filter to include stearic acid and/or isostearic acid. As the inorganic solid UV filter, mention may be made of titanium dioxide (and) aluminum hydroxide (and) stearic acid marketed as "MT-100V" by Tayca, titanium dioxide (and) aluminum hydroxide (and) isostearic acid marketed as "MT- 10EX" by Tayca, and titanium dioxide (and) dimethicone (and) stearic acid (and) aluminum hydroxide marketed as "SA-TTO-S-4" by Miyoshi Kasei.

In a known manner, the silicones in the coating(s) of the inorganic solid UV filter may be

organosilicon polymers or oligomers comprising a linear or cyclic and branched or crosslinked structure, of variable molecular weight, obtained by polymerization and/or polycondensation of suitable functional silanes and essentially composed of a repetition of main units in which the silicon atoms are connected to one another via oxygen atoms (siloxane bond), optionally substituted hydrocarbon radicals being connected directly to the said silicon atoms via a carbon atom.

The term "silicones" also encompasses silanes necessary for their preparation, in particular alkylsilanes.

The silicones used for the coating(s) can preferably be selected from the group consisting of alkylsilanes, polydialkylsiloxanes, and polyalkylhydrosiloxanes. More preferably still, the silicones are selected from the group consisting of octyltrimethylsuane, polydimethylsiloxanes, and

polymethylhydrosiloxanes.

Of course, the inorganic UV filters made of metal oxides may, before their treatment with silicones, have been treated with other surfacing agents, in particular with cerium oxide, dumina, silica, aluminum compounds, silicon compounds or their mixtures.

The coated inorganic solid UV filter may have been prepared by subjecting the inorganic solid UV filter to one or more surface treatments of a chemical, electronic, mechanochemical, and/or mechanical nature with any of the compounds as described above, as well as polyethylenes, metal alkoxides (titanium or aluminum alkoxides), metal oxides, sodium hexametaphosphate, and those shown, for example, in Cosmetics & Toiletries, February 1990, Vol. 105, pp. 53-64.

The coated inorganic solid UV filters are preferable, because the UV filtering effects of the inorganic solid UV filters can be enhanced. In addition, the coating may function as a binder for fixing the UV filters on a core particle.

On the other hand, uncoated inorganic solid UV filters such as uncoated titanium oxide pigments such JA-1 , JP-3, and JA-C marketed by TAYCA can be used as the inorganic solid UV filter. The composite particle according to the present invention can have an effect in that it can provide not a white appearance but a transparent or clear appearance, because the (b) solid UV filters do not aggregate but spread on the (a) core particle. It should be noted that free particles of the (b) solid UV filter(s) easily aggregate to give a white appearance to the skin. The inorganic solid UV filter(s) may be used in the composite particle according to the present invention in proportions such that the weight ratio of the (a) core particle to the inorganic solid UV filter(s) is 90:10 to 10:90, preferably 80:20 to 20:80, and more preferably 70:30 to 30:70.

(Solid Organic UV Filter)

The solid UV filter(s) in the first coating layer(s) on the (a) core particle may be organic solid UV filter(s). If two or more organic solid UV filters are used, they may be the same or different, preferably the same.. The organic solid UV filter may be hydrophilic and/or lipophilic. The organic solid UV filter is properly insoluble in solvents such as water and ethanol commonly used in cosmetics. The term "solid" means solid at 25°C under 1 atm. It is preferable that the organic solid UV filter be in the form of a medium size fine particle such that the mean (primary) particle diameter thereof ranges from 100 nm to less than 300 nm, preferably 100 nm to less than 250 nm, and more preferably 100 nm to less than 200 nm. The mean (primary) particle size or mean (primary) particle diameter here is an arithmetic mean diameter.

The material of the organic solid UV filter(s) is not limited as long as it is organic. If two or more organic solid UV filters are used, the materials) of the organic solid UV filters may be the same as or different from each other.

The organic solid UV filter may comprise at least one organic compound selected from the group consisting of benzotriazole derivatives, oxanilide derivatives, triazine derivatives, triazole derivatives, vinyl-group containing amides, cinnamic acid amides, and sulfonated benzimidazoles.

A preferred class of solid oxanilide UV absorbers is that havin the formula:

in which ¾ and R₂, independently, are Ci-C₁₈ alkyl or -Ci₈ alkoxy. A preferred compound of formula (1) is N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethanediamide. A preferred class of solid triazine UV absorbers is that having the formula:

in which R₃, ¾ and R₅, independently, are H, OH, - s alkoxy, NH₂, NH-Re or N(R_{6 2} in which Re is Q- s alkyl, OR in which Re is Q-Ci₈ alkyl, phenyl, phenoxy or anilino, or pyrrole, in which the respective phenyl, phenoxy or anilino, or pyrrolo moieties are optionally substituted by one, two or three substituents selected from OH, carboxy, CO-NH₂, Q-Ci₈ alkyl or alkoxy, Q-Ci₈ carboxyalkyl, C₅-C₈ cycloalkyl, a methylidenecamphor group, the group -(CH=CH)_mC(=0)-OR₆ in which m is 0 or 1 and s has the same meaning above, or the group

or the corresponding alkali metal, ammonium, mono-, di- or tri-Ci-G} alkylammonium, mono-, di- or tri-C₂-C₄ alkanolammonium salts, or the Ci-C₁₈ alkyl esters thereof.

Preferred compounds of formula (2) are those having one of the formulae:



H

and

as well as 2,4,6-1ris(a^sobutyl-4'-aminobenzalmdonate)-s-triazine and 2,4-bis(diisobutyl-4- aminobenzalmalonate)-6-(4^,-arnmobenzylidenecamphor)-s-1riazm Bis-ethylhexyloxyphenol methoxyphenyl triazine, marketed under the trademark "Tinosorb S" by Ciba-Geigy is in particular preferable.

Particularly preferred compounds of formula (2) are those having the formula:

in which the individual radicals R₇ are the same or different and each is hydrogen; an alkali metal; an ammonium group Ν(¾)₄ in which Rg is hydrogen or an organic radical; Cj-C₂₀ alkyl; or a polyoxyethylene radical which contains from 1 to 10 ethylene oxide units and the terminal OH group of which may be etherified by a -C3 alcohol. In relation to the compounds of formula (30), when R₇ is an alkali metal, it is preferably potassium or, especially sodium; when R₇ is the group N(Rs)₄ in which Rs has its previous meaning, it is preferably a mono-, di- or tri-Ci-Gi alkylammonium salt, a mono-, di- or tri-C₂-C₄ alkanolammonium salt, or a - C₂o alkyl ester thereof; when s is a -Qo alkyl group, it is preferably a C₆-Q₂ alkyl group, more preferably a C₈-C₉ alkyl group, especially a 3,5,5-trimethylpentyl group or, most particularly, a 2- ethylhexyl group; and when Rg is a polyoxyethylene group, this preferably contains from 2-6 ethylene oxide units. A preferred class of solid triazole UV absorbers is that having the formula:

in which Ti is -C₁₈ alkyl or, preferably, hydrogen; and T₂ is hydrogen, hydroxyl, or CrC₁₈ alkyl, optionally substituted by phenyl, preferably ,α-dimethylbenzyl. A further preferred class of solid triazole UV absorbers is that having the formula:

in which T₂ has its previous meaning.

A still further preferred class of solid triazole UV absorbers is that having the formula:

A preferred class of solid vinyl group-containing amide UV absorbers is that having the formula: R9-(Y)_m-CO-C(R₁₀)=C(Rii)-N(R₁₂)(R₁₃) (34) in which R₉ is - s alkyl, preferably C₁-C5 alkyl, or phenyl optionally substituted by one, two or three substituents selected from OH, Ci-Ci₈ alkyl, Ci-C₁₈ alkoxy or CO-ORe in which Re has its previous meaning; Rio, Rn, Rn and Ri₃ are the same or different and each is Q-Ci₈ alkyl, preferably -C5 alkyl, or hydrogen; Y is N or O; and m has its previous meaning.

Preferred compounds of formula (34) are 4-octyl-3-penten-2-one, emyl-3-octylamino-2-butenoate, 3- octylamino- 1 -phenyl-2-buten- 1 -one, and 3-dodecylamino- 1 -phenyl-2-buten- 1 -one.

A preferred class of solid cinnamic acid amide UV absorbers is that having the formula:

in which Ri₄ is hydroxy or Ci-C₄ alkoxy, preferably methoxy or ethoxy; Ri₅ is hydrogen or -C₄ alkyl, preferably methyl or ethyl; and Ri₆ is -(CONH)_m-phenyl in which m has its previous meaning and the phenyl group is optionally substituted by one, two or three substituents selected from OH, Ci-C₁₈ alkyl, C]-Ci₈ alkoxy, or CO-OR5 in which R5 has its previous meaning. Preferably R_½ is phenyl, 4- methoxyphenyl, or the phenylaminocarbonyl group.

A preferred class of solid sulfonated benzimidazole UV absorbers is that having the formula:

in which M is hydrogen or an alkali metal, preferably sodium, an alkaline earth metal, such as magnesium or calcium, or zinc.

In the compounds of formula (1) to (35), Ci-C₁₈ alkyl groups may be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-amyl, n-hexyl, n-heptyl, n-octyl, iso-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, tetradecyl, hexydecyl, or octadecyl; and - g alkoxy groups include methoxy, ethoxy, propoxy, butoxy, n-hexoxy, n-heptoxy, n-octoxy, iso-octoxy, n-iionoxy, n-decoxy, n-undecoxy, n- dodecoxy, tetradecoxy, hexadecoxy or octadecoxy, and methoxy and ethoxy being preferred.

Ci-C₁₈ carboxyalkyl includes carboxymethyl, carboxyethyl, carboxypropyl, carboxyisopropyl, carboxybutyl, carboxyisobutyl, carboxybutyl, carboxyamyl, carboxyhexyl, carboxyheptyl,

carboxyoctyl, carboxyisooctyl, carboxynonyl, carboxydecyl, carboxyundecyl, carboxydodecyl, carboxytetradecyl, carboxyhexadecyl, and carboxyoctadecyl, carboxymethyl being preferred.

C₅-C₈ cycloalkyl includes cyclopentyl, cyclohexyl, and cyclooctyl.

The compounds of formula (1) to (35) are known. The compounds of formula (30) are described, together with their production, in U.S. Pat. No. 4,617,390.

It is preferable that the organic solid UV filters) be a benzotriazole derivative, in particular, a phenylbenzotriazole derivative such as a drometrizole trisiloxane, marketed under the trademark "Silatrizole" by Rhodia Chimie or "Mexoryl XL" by L'Oreal, as represented below.

The composite particle according to the present invention can have an effect in that it can provide a transparent or clear appearance, because the organic solid UV filters do not aggregate but spread on the (a) core particle. It should be noted that free particles of the organic solid UV filter(s) can easily aggregate.

Further, if organic solid UV filters) is/are used with inorganic solid UV filter(s), the composite particle according to the present invention can have an additional effect in that the particles of the inorganic solid UV filter(s) can be well dispersed in the first coating layer due to the presence of the organic solid UV filter(s), and therefore, the inorganic solid UV filters) can be present in the first coating layer in the form of primary particles. On the other hand, in the above case, the particles of the organic solid UV filter(s) can also be well dispersed in the first coating layer due to the presence of the inorganic solid UV filter(s), and therefore, the organic solid UV filter(s) can be present in the first coating layer in the form of primary particles. Accordingly, the UV filtering effects by the inorganic solid UV filter(s) as well as the organic solid UV filter(s) can be enhanced together.

The organic solid UV filters) may be used in the composite particle according to the present invention in proportions such that the weight ratio of the (a) core particle to the organic solid UV filter(s) is 90:10 to 10:90, preferably 80:20 to 20:80, and more preferably 70:30 to 30:70.

{First Layer}

The (a) core particle is at least partially covered with at least one first coating layer comprising at least one (b) solid UV filter. Preferably, 10% or more of the surface of the (a) core particle can be covered by the first coating layer(s). More preferably, 50% or more of the surface of the (a) core particle can be covered by the first coating layer(s). More preferably, 80% or more of the surface of the (a) core particle can be covered by the first coating layer(s). Most preferably, the entire surface of the (a) core particle can be covered by the first coating layer(s).

The (b) solid UV filter in the first coating layer(s) on the core particle may have a mean particle size of from 1 nm to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to 50 nm.

Due to the use of the (b) solid UV filter, the composite particle according to the present invention can have UV shielding effects.

The thickness of the first coating layer may vary depending on several factors such as the size of the (b) solid UV filter. Typically, depending on the mean particle size of the (b) solid UV filter, the thickness of the first coating layer may range from 1 nm to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to less than 50 nm. If there are two or more first coating layers on the (a) core particle, the thickness and the composition of the first coating layers may be the same as or different from each other.

The first coating layer(s) may comprise, other than the (b) solid UV filter(s), any additional material(s) such as at least one additional liquid UV filter. The additional material(s) may be present in an amount ranging from 1 to 50% by weight relative to the total weight of the first coating layer(s).

The amount of the first coating layer(s) may be from 0.1 to 30% by weight, preferably from 1 to 20% by weight, and more preferably from 5 to 15% by weight, relative to the total weight of the composite particle.

(Additional UV Filter)

As described above, the first coating layer(s) on the (a) core particle may further comprise at least one additional liquid UV filter. If two or more additional liquid UV filters are used, they may be the same or different, preferably the same. The additional liquid UV filter may be hydrophilic and/or lipophilic.

The term "liquid" means liquid at 25°C under 1 atm. The additional liquid UV filter may be made from at least one organic or inorganic material, preferably at least one inorganic material.

The additional liquid UV filter(s) may be an organic liquid UV filter(s) selected from the group consisting of anthranilic derivatives; dibenzoylmethane derivatives; liquid cinnarnic derivatives;

sahcylic derivatives; camphor derivatives; benzophenone derivatives; β,β-diphenylacrylate derivatives; liquid triazine derivatives; liquid benzotriazole derivatives; benzalmalonate derivatives; benzimidazole derivatives; imidazoline derivatives; bis-benzoazolyl derivatives; p-arninobenzoic acid (PABA) and derivatives thereof; methylenebis(hydroxyphenylbenzotriazole) derivatives; benzoxazole derivatives; screening polymers and screening silicones; dimers derived from a-alkylstyrene; 4,4-diarylbutadienes; octocrylene and derivatives thereof, guaiazulene and derivatives thereof, rutin and derivatives thereof, flavonoids, biflavonoids, oryzanol and derivatives thereof, quinic acid and derivatives thereof, phenols, retinol, cysteine, aromatic amino acids, peptides having an aromatic amino acid residue, and mixtures thereof.

Mention may be made, as examples of the organic liquid UV filters, of those denoted below under their INCI names, and mixtures thereof.

Ajnthranilic derivatives: Menthyl anthranilate, marketed under the trademark "Neo Heliopan MA" by Haarmann and Reimer.

Dibenzoylmethane derivatives: Butyl methoxydibenzoylmethane, marketed in particular under the trademark "Parsol 1789" by Hoffmann-La Roche; and isopropyl dibenzoylmethane.

Liquid cinnarnic derivatives: Ethylhexyl methoxycinnamate, marketed in particular under the trademark "Parsol MCX" by Hoffinann-La Roche; isopropyl methoxycinnamate; isopropoxy methoxycinnamate; isoamyl methoxycinnamate, marketed under the trademark "Neo Heliopan E 1000" by Haarmann and Reimer; Cinoxate (2-ethoxyethyl-4-methoxy cinnamate); DEA

methoxycinnamate; diisopropyl methylcinnamate; and glyceryl ethylhexanoate dimethoxycinnamate.

Salicylic derivatives: Homosalate (homomentyl salicylate), marketed under the trademark "Eusolex HMS" by Rona/EM Industries; ethylhexyl salicylate, marketed under the trademark "Neo Heliopan OS" by Haarmann and Reimer; glycol salicylate; butyloctyl salicylate; phenyl salicylate; dipropyleneglycol salicylate^ marketed under the trademark "Dipsal" by Scher; and TEA salicylate, marketed under the trademark "Neo Heliopan TS" by Haarmann and Reimer.

Camphor derivatives, in particular, benzylidenecamphor derivatives: 3-benzylidene camphor, manufactured under the trademark "Mexoryl SD" by Chimex; 4-methylbenzylidene camphor, marketed under the trademark "Eusolex 6300" by Merck; benzylidene camphor sulfonic acid, manufactured under the trademark "Mexoryl SL" by Chimex; camphor benzalkonium methosulfate, manufactured under the trademark "Mexoryl SO" by Chimex; terephthalylidene dicamphor sulfonic acid, manufactured under the trademark "Mexoryl SX" by Chimex; and polyacrylamidomethyl benzylidene camphor, manufactured under the trademark "Mexoryl S W" by Chimex.

Benzophenone derivatives: Benzophenone-1 (2,4-dihydroxybenzophenone), marketed under the trademark "Uvinul 400" by BASF; benzophenone-2 (tetrahydroxybenzophenone), marketed under the trademark "Uvinul D50" by BASF; benzophenone-3 (2-hydroxy-4-methoxybenzophenone) or Oxybenzone, marketed under the trademark "Uvinul M40" by BASF; benzophenone-4

(hydroxymethoxy benzophonene sulfonic acid), marketed under the trademark "Uvinul MS40" by BASF; benzophenone-5 (sodium hydroxymethoxy benzophenone sulfonate); benzophenone-6 (dihydroxy dimethoxy benzophenone); marketed under the trademark "Helisorb 11 " by Norquay; benzophenone-8, marketed under the trademark "Spectra-Sorb UV-24" by American Cyanamid; benzophenone-9 (disodium dihydroxy dimethoxy benzophenonedisulfonate), marketed under the trademark "Uvinul DS-49" by BASF; benzophenone- 12, and n-Hexyl 2-(4-diethylamino-2- hydroxybenzoyi)benzoate. β,β-diphenylacrylate derivatives: Octocrylene, marketed in particular under the trademark "Uvinul N539" by BASF; and etocrylene, marketed in particular under the trademark "Uvinul N35" by BASF.

Liquid triazine derivatives: Diethylhexyl butamido triazone, marketed under the trademark "Uvasorb HEB" by Sigma 3V; 2,4,6-tris(dineopentyl 4'-arnmobenzalmalonate)-s-triazine; and the symmetrical triazine screening agents described in U.S. Pat. No. 6,225,467, WO 2004/085412 (see Compounds 6 and 9) or the document "Symmetrical Triazine Derivatives", IP.COM Journal, IP.COM INC, WEST HENRIETTA, NY, US (20 Sep. 2004), in particular the 2,4,6-tris(biphenyl)-l ,3,5-triazines (especially 2,4,6-tris(biphenyl-4-yl)-l,3,5-triazine), and 2,4,6-ΐπ8(ίεφηε^1)-1,3,5^3ζίη6, which is taken up again in WO 06/035000, WO 06/034982, WO 06/034991, WO 06/035007, WO 2006/034992 and WO 2006/034985.

Liquid benzotriazole derivatives, in particular, phenylbenzotriazole derivatives: 2-(2H-benzotriazole-2- yl)-6-dodecyl-4-methylpheno, branched and linear; and those described in USP 5240975.

Benzalmalonate derivatives: Dineopentyl 4'-methoxybenzalmalonate, and polyorganosiloxane comprising benzalmalonate functional groups, such as polysilicone- 15, marketed under the trademark "Parsol SLX" by Hoffmann-LaRoche.

Benzimidazole derivatives, in particular, phenylbenzimidazole derivatives: Phenylbenzimidazole sulfonic acid, marketed in particular under the trademark "Eusolex 232" by Merck, and disodium phenyl dibenzimidazole tetrasulfonate, marketed under the trademark "Neo Heliopan AP" by

Haarmann and Reimer.

Imidazoline derivatives: Ethylhexyl dimethoxybenzylidene dioxoirnidazoline propionate. Bis-benzoazolyl derivatives: The derivatives as described in EP-669,323 and U.S. Pat. No. 2,463,264. Para-aminobenzoic acid and derivatives thereof: PABA (p-aminobenzoic acid), ethyl PABA, ethyl dihydroxypropyl PABA, pentyl dimethyl PABA, ethylhexyl dimethyl PABA, marketed in particular under the trademark "Escalol 507" by ISP, Glyceryl PABA, and PEG-25 PABA, marketed under the trademark "Uvinul P25" by BASF.

Methylenebis(hydroxyphenylbenzotriazole) derivatives: Methylene bis-benzotriazolyl

tetramethylbutylphenol, marketed in the solid form under the trademark "Mixxim BB/100" by Fairmount Chemical or in the micronized form in aqueous dispersion under the trademark "Tinosorb M" by Ciba Specialty Chemicals, and the derivatives as described in U.S. Pat. Nos. 5,237,071, 5,166,355, GB-2,303,549, DE-197,26,184 and EP-893,119.

Benzoxazole derivatives: 2,4-bis[5-l(dimemylpropyl)benzoxazol-2-yl-(4-phenyl)irnmo

ethymexyl)imino-l,3,5-triazine, marketed under the trademark of Uvasorb K2A by Sigma 3V.

Screening polymers and screening silicones: The silicones described in WO 93/04665. Dimers derived from a-alkylstyrene: The dimers described in DE- 19855649. 4,4-diarylbutadiene Derivatives: l,l-Dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene. Octocrylene and derivatives thereof: Octocrylene.

Quaiazulene and derivatives thereof: Guaiazulene and sodium guaiazulene sulfonate.

Rutin and derivatives thereof: Rutin and glucosylrutin.

Flavonoids: Robustin (isoflavonoid), genistein (flavonoid), tectochrysin (flavonoid) and hispidone (flavonoid).

Biflavonoids: Lanceolatin A, lanceolatin B and hypnumbiflavonoid A. Oryzanol and derivatives thereof: Γ-oryzanol. Quinic acid and derivatives thereof: Quinic acid. Phenols: Phenol. Retinols: Retinol.

Cysteines: L-cysteine.

Peptides having an aromatic amino acid residue: Peptides having tryptophan, tyrosine, or

phenylalanine.

The preferred organic liquid UV filter(s) may be selected from:

butyl methoxydibenzoylmethane, ethylhexyl methoxycinnamate, homosalate, ethylhexyl salicylate, octocrylene, phenylbenzimidazole sulfonic acid, benzophenone-3, benzophenone-4, benzophenone-5, n-hexyl 2-(4-diemylamino-2-hydroxybenzoyl)benzoate, 4-methylbenzylidene camphor,

terephthalylidene dicamphor sulfonic acid, disodium phenyl dibenzimidazole tetrasulfonate, ethylhexyl triazone, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylhexyl butamido triazone, 2,4,6- tris(dineopentyl 4'-aminobenzalmalonate)-s-triazine, 2,4,6-tris(diisobutyl 4'-aminobenzalmalonate)-s- triazine, 2,4,6-1ris(biphenyl-4-yl)-l,3,5-triazine, 2,4,6-tris(teφhenyl)-l,3,5-triazine, methylene bis- benzotriazolyl tetramethylbutylphenol, polysiUcone-15, dineopentyl 4'-methoxybenzalmalonate, 1,1- dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene, 2,4-bis[5- 1 (dimethylpropyl)benzoxazol-2-yl- (4-phenyl)immo]-6-(2-emylhexyl)immo-l,3,5-triazine, and their mixtures. More preferable organic liquid UV filter is butyl methoxydibenzoylmethane(Avobenzone).

The additional liquid UV filter(s) may be used in the composite particle according to the present invention in proportions such that the weight ratio of the (a) core particle to the additional UV filter(s) is 50:50 to 90: 10, preferably 50:50 to 80:20, and more preferably 50:50 to 70:30.

{Hydrophobic Block Copolymer} The second coating layer of the composite particle according to the present invention comprises at least one (c) hydrophobic block copolymer. If two or more (b) hydrophobic block copolymers are used, they may be the same or different.

It is preferable that the (c) hydrophobic block copolymer have elasticity. Specifically, it is preferable that the (c) hydrophobic block copolymer have a recovery ratio of 50% or more, preferably 60% or more, and more preferably 70% or more.

The recovery ratio can be determined by the following steps:

(1) A (c) hydrophobic block copolymer is put on a substrate;

(2) The (c) hydrophobic block copolymer is compressed by a probe, for example, with a shape of a cylinder having a diameter of 35 mm, and a pressure sensor, at a compression speed of 0.1 mm/s, until 1 kgf of force is detected by the pressure sensor;

(3) A curve of the force value detected by the pressure sensor depending on the distance between the substrate and the probe is determined;

(4) The integral value (1 ) of the curve (Y axis = the force value, X axis = the distance) is calculated.

(5) The compression is stopped when the detected force reaches 1 kgf, and the probe is moved at a speed of 0.1 mm/s to an opposite direction to release the (c) hydrophobic block copolymer;

(6) A curve of the force value detected by the pressure sensor depending on the distance between the substrate and the probe is determined again;

(7) The integral value (2) of the curve is calculated;

(8) The ratio of (2)/(l) is determined as the recovery ratio; and

(9) The above steps (1) to (8) are repeated three times and the average value of the recovery ratio is calculated. It is preferable that the (c) hydrophobic block copolymer be thermoplastic.

It is preferable that the blocks of the (c) hydrophobic block copolymer have different glass transition temperatures (Tg). One of the blocks may have a Tg of 50°C or more, preferably 70°C or more, and more preferably 90°C ormore.

Another of the blocks may have a Tg of less than 50°C, preferably 0°C or less, and more preferably - 50°C or less. The (c) hydrophobic block copolymer may be a block copolymer of at least one (meth)acrylate block and at least one fluorinated block and/or at least one silicone block.

As examples of the block copolymer of the (meth)acrylate block and the fluorinated block and/or the silicone block, mention may be made of fluorinate/acrylate copolymer marketed as "Modiper F606" and dimethicone/acrylates copolymer marketed as "Modiper FS700" by NOF in Japan.

It is preferable that the (c) hydrophobic block copolymer be a hydrocarbon-based block copolymer. It is preferable that the hydrocarbon-based block copolymer be an amorphous polymer. The term

"amorphous polymer" means a polymer that does not have a crystalline form. The hydrocarbon-based block copolymer is also preferably film-forming, i.e. it is capable of foirning a film when applied to the skin and the like. The hydrocarbon-based block copolymer may especially be a diblock, triblock, multiblock, radial or star copolymer, or mixtures thereof.

Such hydrocarbon-based block copolymers are described in patent application US-A-2002/005 562 and in patent USP 5 221 534.

The hydrocarbon-based block copolymer preferably comprises at least a styrene monomer (i.e., is obtained from at least a styrene monomer).

The hydrocarbon-based block copolymer may contain at least one block whose glass transition temperature is less than 20°C, preferably less than or equal to 0°C, more preferably less than or equal to -20°C and even more preferably less than or equal to -40°C. The glass transition temperature of the said block may be between -150°C and 20°C and especially between -100°C and 0°C.

It is preferable that the hydrocarbon-based block copolymer used in the present invention be an amorphous copolymer formed by polymerization of olefins. The olefin may especially be an elastomeric ethylenically unsaturated monomer.

Examples of olefins that may be mentioned include ethylenic carbide monomers, especially containing one or two ethylenic unsaturations and containing from 2 to 5 carbon atoms, such as ethylene, propylene, butadiene, isoprene or pentadiene.

Advantageously, the hydrocarbon-based block copolymer may be an amorphous block copolymer of styrene and of olefin(s). It is preferable that the hydrocarbon-based block copolymer comprise at least one styrene block and at least one block comprising units chosen from butadiene, ethylene, propylene, butylene, and isoprene or a mixture thereof, which are optionally hydrogenated.

According to one preferred embodiment, the hydrocarbon-based block copolymer is hydrogenated to reduce the residual ethylenic unsaturations after the polymerization of the monomers.

In particular, the hydrocarbon-based block copolymer is a copolymer, optionally hydrogenated, containing styrene blocks and ethylene/C₃-C₄ alkylene blocks. According to one preferred embodiment, the hydrocarbon-based block copolymer used in the present invention may be a diblock copolymer, which is preferably hydrogenated, preferably chosen from styrene-ethylene/propylene copolymers, styrene-ethylene/butadiene copolymer, styrene- ethylene/butylene copolymers, and styrene-ethylene/isoprene copolymers.

According to one embodiment of the present invention, a linear diblock copolymer based on styrene and ethylene/propylene, or on styrene and ethylene/butylene, or a hydrogenated styrene/isoprene copolymer is preferable as the hydrocarbon-based block copolymer. Such a diblock copolymer is especially sold under the name Kraton® G1701EU, Kraton® G1701H, and Kraton® G1730M by the company Kraton Polymers.

According to another preferred embodiment, the hydrocarbon-based block copolymer used in the present invention may be a triblock copolymer, which is preferably hydrogenated, and preferably chosen from styrene-ethylene/propylene-styrene copolymers, styrene-ethylene/butadiene-styrene copolymers, styrene-ethylene/butylene-styrene copolymers, styrene-ethylene/isoprene-styrene copolymers, styrene-isoprene-styrene copolymers, and styrene-butadiene-styrene copolymers.

Triblock copolymers are especially sold under the names Kraton® Gl 650, Kraton® Gl 651 , Kraton® G1652, Kraton® G1654, Kraton® G1657MKraton® Dl 101, Kraton® Dl 102, and Kraton® Dl 160 by the company Kraton Polymers.

According to one embodiment of the present invention, the hydrocarbon-based block copolymer may be a hydrogenated styrene-ethylene/butylene-styrene triblock copolymer or a hydrogenated styrene/butadiene copolymer. Such a triblock copolymer is especially sold under the name Kraton® G1651, Kraton® G1654, and Kraton® G1657M, and by the company Kraton Polymers.

According to one preferred embodiment of the present invention, it is especially possible to use, as the hydrocarbon-based block copolymer, a mixture of a styrene-ethylene butylene-styrene triblock copolymer and of a styrene-ethylene/butylene diblock copolymer. According to another preferred embodiment, the composition according to the present invention may comprise, as the hydrocarbon-based block copolymer, a mixture of styrene-butylene/ethylene-styrene hydrogenated triblock copolymer and of ethylene-propylene-styrene hydrogenated star polymer, such a mixture possibly being especially in isododecane or in another oil. Such mixtures are sold, for example, by the company Penreco under the trade names Versagel® M5960 and Versagel® M5670.

Advantageously, a diblock copolymer such as those described previously is used as a polymeric gelling agent, in particular a styrene-ethylene/propylene diblock copolymer or a mixture of diblock and triblock copolymers, as described previously. It is preferable that the hydrocarbon-based block copolymer be selected from the group consisting of a styrene-ethylene/butylene-styrene triblock copolymer, a styrene-ethylene/butylene diblock copolymer, a styrene-ethylene/isoprene-styrene triblock copolymer, a styrene/ethylene-propylene diblock copolymer, a styrene-ethylene/isoprene diblock copolymer, and a mixture thereof. The weight ratio of the (a) core particle(s) to the (c) hydrophobic block copolymers) may be from 50:50 to 99:1, preferably from 60:40 to 95:5, and more preferably from 70:30 to 90:10.

The (c) hydrophobic block copolymer may be present in the composite particle in a content ranging from 1 to 35% by weight, preferably ranging from 4 to 30% by weight, and more preferably from 8 to 25% by weight, relative to the total weight of the composite particle. {Second Layer}

The first layer is at least partially covered with at least one second coating layer comprising at least one (c) hydrophobic block copolymer. Preferably, 10% or more of the surface of the outermost first coating layer can be covered by the second coating layer(s). More preferably, 50% or more of the surface of the outermost first coating layer can be covered by the second coating layer(s). More preferably, 80% or more of the surface of the outermost first coating layer can be covered by the second coating layer(s). Most preferably, the entire surface of the outermost first coating layer can be covered by the second coating layer(s).

Due to the use of the (c) hydrophobic block copolymer, the composite particle according to the present invention can maintain enhanced UV shielding effects. The thickness of the second coating layer may vary depending on several factors such as the type of the (c) hydrophobic block copolymer. The thickness of the second coating layer may range from 1 nm to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to less than 50 nm.

If there are two or more second coating layers on the first coating layer, the thickness and the composition of the second coating layers may be the same as or different from each other.

The second coating layer(s) may comprise, other than the (c) hydrophobic block copolymer, any additional material(s). The additional material(s) may be present in an amount ranging from 1 to 50% by weight relative to the total weight of the second coating layer(s). It is preferable, however, that the second coating layer(s) consist(s) of the (c) hydrophobic block copolymer.

The amount of the second coating layer(s) may be from 0.01 to 30% by weight, preferably from 0.1 to 20% by weight, and more preferably from 0.3 to 15% by weight, relative to the total weight of the composite particle.

[Method for Preparing Composite Particle]

The composite particle according to the present invention can be prepared by subjecting (a) at least one core particle, (b) at least one solid UV filter, and (c) at least one hydrophobic block copolymer to a mechanochemical fusion process.

The (a) core particle, the (b) solid UV filter, and the (c) hydrophobic block copolymer are as explained above. Mechanochemical fusion process means a process in which mechanical power such as an impact force, friction force or shear force is applied to a plurality of subjects to cause fusion between the subjects.

The mechanochemical fusion process may be performed by, for example, an apparatus comprising a rotating chamber and a fixed inner piece with a scraper, such as a mechanofusion system marketed by Hosokawa Micron Corporation in Japan.

It is preferable to use a hybridizer process as the mechanochemical fusion process. The hybridizer process was developed in the 1980s. The hybridizer process is a class of

mechanochemical fusion processes in which strong mechanical power is applied to a plurality of particles to cause a mechanochemical reaction to form a composite particle. According to the hybridizer process, the mechanical power is imparted by a high speed rotor which can have a diameter from 10 cm to 1 m, and can rotate at a speed of 1,000 rpm to 100,000 rpm.

Therefore, the hybridizer process can be defined as a mechanochemical fusion process using such a high speed rotor. The hybridizer process is performed in air or under dry conditions. Thus, due to the high speed rotation of the rotor, high speed air flow may be generated near the rotor. However, some liquid materials may be subjected to the hybridizer process together with solid materials. The term "hybridizer process" has been used as a technical term.

The hybridizer process can be performed by using a hybridization system marketed by, for example, Nara Machinery in Japan, in which at least two types of particles, typically core particles and fine particles, are fed into a hybridizer equipped with a high speed rotor having a plurality of blades in a chamber under dry conditions, and the particles are dispersed in the chamber and mechanical and thermal energy (e.g., compression, friction and shear stress) are imparted to the particles for a relatively short period of time such as 1 to 10 minutes, preferably 1 to 5 minutes. As a result, one type of particles (e.g., fine particles) is embedded or fixed on the other type of particles (e.g., core particle) to form composite particles. It is preferable that the particles have been subjected to electrostatic treatments) such as shaking to form an "ordered mixture" in which one type of particles is spread to cover the other type of particles. The hybridizer process can also be performed by using a theta composer marketed by Tokuju Corporation in Japan. The hybridizer process can also be performed by using a Composi Hybrid or a Mechano Hybrid marketed by Nippon Coke.

According to one embodiment of the present invention, for example, the (a) core particle(s), the (b) solid UV filter(s) and the (c) hydrophobic block copolymers) as well as optionally additional material(s) such as additional liquid UV filter(s), if necessary, can be fed into such a hybridizer to form a composite particle. The hybridizer process can be performed by using a rotor rotating at about 8,000 rpm (100 m/sec) for about 3 minutes.

If small and large core particles are used as the (a) core particles, the small core particle(s) and the large core particle(s) can be used in proportions such that the weight ratio of the small core particle(s) to the large core particle(s) is 10:90 to 90: 10, preferably 20:80 to 80:20, and more preferably 30:70 to 70:30.

In a particular embodiment, the weight ratio of the small core particle(s)/the large core particle(s)/the

(b) solid UV filter(s) may be 20:80:30 to 80:20:30, preferably 30:70:30 to 70:30:30, and more preferably 40:60:30 to 60:40:30.

In a preferred embodiment, the weight ratio of (the (a) core particle(s)+the (b) solid UV filter(s)): the

(c) hydrophobic block copolymer may be from 100:1 to 100:50, preferably from 100:5 to 100:40, and more preferably from 100:10 to 100:30.

The mechanochemical fusion process, in particular the hybridizer process, enables the provision of a composite particle in which the (a) core particle(s) is/are at least in part covered by at least one first coating layer comprising at least one (b) solid UV filter, and optionally at least one additional liquid UV filter, and the first coating layer is at least in part cover by at least one second coating layer comprising at least one (c) hydrophobic block copolymer. Furthermore, the mechanochemical fusion process, in particular the hybridizer process, can provide an ordered array (e.g., uniform coverage) of the (b) solid UV filter(s) on the (a) core particle(s) and provides strong bonds at the surface of the (a) core particle and the first coating layer comprising the (b) solid UV filter(s), and optionally additional liquid UV filter(s).

If a combination of small and large core particles are used, the (b) solid UV filter can be effectively bound on the surface of the (a) core particle(s) due to the anchoring effects caused by the collision of the large core particles against the small core particles. Therefore, the UV filtering effects can be further enhanced.

Since the first layer(s) including the (b) solid UV filter(s) is further coated with the second coating layer(s) including the (c) hydrophobic block copolymers), the (b) solid UV filter(s) is/are firmly attached to the (a) core particle(s), and difficult to detach from the (a) core particle(s). Accordingly, the composite particle according to the present invention can maintain enhanced UV shielding effects provided by the (b) solid UV filter(s), even in contact with anionic surfactants and/or water.

It should be noted that the mechanochemical fusion process, in particular the hybridizer process, is quite different from other processes using, for example, a beads mill and a jet mill. In fact, a beads mill causes pulverization or aggregation of core particles, and a jet mill causes pulverization of core particles, and it is difficult to form a uniform coating of a core particle by fine particles.

If necessary, an additional process for further coating the composite particle with, for example, UV filter(s) and/or coloring material(s) may be performed. As a result of this additional process, the composite particle according to the present invention may be coated with at least one further layer comprising, for example, UV filters) and/or coloring material(s), preferably consisting of UV filters) and/or coloring material(s).

[Composition]

The composition, preferably cosmetic composition according to the present invention includes the composite particle according to the present invention.

The composite particle, as described above, according to the present invention can be present in the composition according to the present invention in an amount ranging from 0.01% to 99% by weight, preferably from 0.1% to 50% by weight, and more preferably from 1% to 30% by weight, relative to the total weight of the composition.

Preferably, the composite particle according to the present invention or the composition according to the present invention may be applied to a keratin substance such as skin, hair, and nails, providing superior UV shielding effects, because the composite particle can exhibit good UV filtering effects possibly with a transparent or clear appearance without the risk of affecting the keratin substance.

Since the composite particle according to the present invention can reduce free particles which have a high friction coefficient such that they do not easily spread on the skin and provide an unpleasant feeling during use, the composition according to the present invention has reduced friction, and therefore, can provide the effect of a better feeling during use.

The composition according to the present invention may further comprise at least one filler and/or at least one oil. As used herein, the term "filler" should be understood as meaning colorless natural or synthetic particles of any shape which are insoluble in the medium of the composition, regardless of the temperature at which the composition is manufactured.

The fillers may be inorganic or organic and of any shape (for instance, platelet, spherical, and oblong shapes) and with any crystallographic form (for example, sheet, cubic, hexagonal, orthorhombic, and the like). Examples of suitable additional fillers include, but are not limited to, talc; mica; silica; kaolin; powders of polyamide such as Nylon®; poly- -3-alanine powders; polyethylene powders;

polyurethane powders, such as the powder formed of hexamethylene diisocyanate and trimethylol hexyllactone copolymer sold under the name Plastic Powder D-400 by Tosbiki; the powders formed of tetrafluoroethylene polymers (Teflon®); lauroyllysine; starch; boron nitride; polymeric hollow microspheres, such as microspheres of poly(vinylidene chloride)/acrylonitrile, for example Expancel® (Nobel Industrie), and microspheres of acrylic acid copolymers; silicone resin powders, for example, silsesquioxane powders (for instance, silicone resin powders disclosed in European Patent No. 0293 795 and Tospearls® from Toshiba); poly(methyl methacrylate) particles; precipitated calcium carbonate; magnesium carbonate; basic magnesium carbonate; hydroxyapatite; hollow silica microspheres; glass microcapsules; ceramic microcapsules; metal soaps derived from organic carboxylic acids comprising from 8 to 22 carbon atoms, for example, from 12 to 18 carbon atoms, such as zinc stearate, magnesium stearate, lithium stearate, zinc laurate, and magnesium myristate; barium sulphate; and mixtures thereof.

The filler may be present in the composition according to the present invention in an amount ranging from 0.1% to 80% by weight, with respect to the total weight of the composition, for example, from 1 % to 25% by weight, or from 3% to 15% by weight.

The term "oil" is understood to mean a fatty substance which is liquid at ambient temperature (25°C).

Use may be made, as oils which can be used in the composition of the present invention, for example, of hydrocarbon oils of animal origin, such as perhydrosqualene (or squalane); hydrocarbon oils of vegetable origin, such as triglycerides of caprylic/capric acids, for example those marketed by

Stearineries Dubois or those marketed under the trademarks Miglyol 810, 812 and 818 by Dynamit Nobel, or oils of vegetable origin, for example sunflower, maize, soybean, cucumber, grape seed, sesame, hazelnut, apricot, macadamia, arara, coriander, castor, avocado or jojoba oil, or shea butter oil; synthetic oils; silicone oils, such as volatile or non-volatile polymethylsiloxanes (PDMSs) comprising a linear or cyclic silicone chain which are liquid or paste at ambient temperature; fluorinated oils, such as those which are partially hydrocarbon and/or silicone, for example those described in JP-A-2- 295912; ethers, such as dicaprylyl ether (CTFA name); esters, such as benzoate C₁₂-C₁₅ fatty alcohols (Finsolv TN from Finetex); arylalkyl benzoate derivatives, such as 2-phenylethyl benzoate (X-Tend 226 from ISP); amidated oils, such as isopropyl N-lauroylsarcosinate (Eldew SL-205 from

Ajinomoto); and their mixtures.

The oily phase can also comprise one or more fatty substances selected, for example, from fatty alcohols (cetyl alcohol, stearyl alcohol, cetearyl alcohol), fatty acids (stearic acid) or waxes (paraffin wax, polyethylene waxes, carnauba wax, beeswax). The oily phase can comprise lipophilic gelling agents, surfactants or also organic or inorganic particles.

The oily phase can preferably represent from 1 to 70% by weight, with respect to the total weight of the composition according to the present invention, for example, from 1% to 25% by weight, or from 3% to 15% by weight. The composition according to the present invention may further comprise at least one additional conventional cosmetic ingredient which may be chosen, for example, from coloring pigments, hydrophilic or lipophilic gelling and/or thickening agents, anionic, cationic, nonionic, amphoteric or zwitterionic surfactants, antioxidants, fragrances, preservatives, neutralizing agents, sunscreens, vitamins, moisturizing agents, self-tanning compounds, antiwrinkle active agents, emollients, hydrophilic or lipophilic active agents, agents for combating pollution and/or free radicals, sequestering agents, film-forming agents, dermo-decontracting active agents, soothing agents, agents which stimulate the synthesis of dermal or epidermal macromolecules and/or which prevent their decomposition, antiglycation agents, agents which combat irritation, desquamating agents, depigmenting agents, antipigmenting agents, propigmenting agents, NO-synthase inhibitors, agents which stimulate the proliferation of fibroblasts and/or keratinocytes and/or the differentiation of keratinocytes, agents which act on microcirculation, agents which act on energy metabolism of the cells, healing agents, and mixtures thereof

The composition according to the present invention may be in various forms, for example, suspensions, dispersions, solutions, gels, emulsions, such as oil-in-water (O/W), water-in-oil (W/O), and multiple (e.g., W/O/W, polyol/O W, and 0/W/O) emulsions, creams, foams, sticks, dispersions of vesicles, for instance, of ionic and/or nonionic lipids, two-phase and multi-phase lotions, sprays, powders, and pastes. The composition according to the present invention may be anhydrous, for example, it can be an anhydrous paste or stick. The composition according to the present invention may also be a leave-in composition.

According to one embodiment, the composition according to the present invention may be in the form of a powdery composition or a liquid or solid composition, such as an oily-solid composition or an anhydrous composition.

In particular, the powdery composition according to the present invention can have reduced friction which provides a smooth feeling during use, and can have good compactability which provides high stability against physical impact, due to the inclusion of the composite particle according to the present invention.

Furthermore, the powdery composition according to the present invention can show preferable cosmetic effects such as good fitting to the skin, homogeneous appearance, hiding the color of the skin, hiding the pores and lines on the skin, making the pores and lines on the skin less noticeable, and enhanced matt appearance, due to the inclusion of the composite particle according to the present invention.

On the other hand, the liquid composition according to the present invention can show good visual optical effects such as matt and haze effects, due to the inclusion of the composite particle according to the present invention.

In any event, the powdery and liquid composition according to the present invention has better UV filtering effects, in addition to reducing the risk of fine particles of solid UV filter(s) penetrating into the sldnviatx)res onthe skin.

According to another embodiment, the composition according to the present invention may be in the form of, for example, a compact powder, a lotion, a serum, a milk, a cream, a base foundation, an undercoat, a make-up base coat, a foundation, a face powder, cheek rouge, a lipstick, a lip cream, an eye shadow, an eyeliner, a loose powder, a concealer, a nail coat, mascara, a sunscreen and the like. According to another embodiment, the composition according to the present invention may be in the form of a foam. According to this embodiment, the composition according to the present invention can be packaged in a foam dispenser. It can involve either products referred to as "aerosols" dispensed from a pressurized container by means of a propellant gas and thus forming a foam at the time of their dispensing, or products dispensed from a container by means of a mechanical pump connected to a dispensing head where the passage of the composition through the dispensing head transforms it into a foam in the area of the outlet orifice of such a head at the latest.

According to a first variant, the dispenser can be an aerosol furthermore containing the composition according to the present invention; and a propellant gas. For the purposes of the present invention, the term "propellant" means any compound that is gaseous at a temperature of 20°C and at atmospheric pressure, and that can be stored under pressure in liquid or gaseous form in an aerosol container. The propellant may be chosen from optionally halogenated volatile hydrocarbons, such as n-butane, propane, isobutane, pentane or a halogenated hydrocarbon, and mixtures thereof. Carbon dioxide, nitrous oxide, dimethyl ether (DME), nitrogen or compressed air may also be used as propellant. Mixtures of propellants may also be used. Dimethyl ether and/or non-halogenated volatile hydrocarbons are preferably used.

The propellant gas which can be used may be chosen among the previously mentioned gases and in particular among carbon dioxide, nitrogen, nitrogen oxide, dimethyl ether, volatile hydrocarbons such as butane, isobutane, propane and pentane, and mixtures thereof.

According to another variant, the composition according to the present invention can be in a "pump bottle" type foam dispenser. These dispensers include a dispensing head for delivering the composition, a pump and a plunger tube for transferring the composition from the container, into the head, for dispensing the product. The foam is formed by forcing the composition to pass through a material including a porous substance such as a sintered material, a filtering grid of plastic or metal, or similar structures.

Such dispensers are known to a person skilled in the art and are described in the patents: US patent 3,709,437 (Wright), US patent 3,937,364 (Wright), US patent 4,022,351 (Wright), US patent 4,1147,306 (Bennett), US patent 4,184,615 (Wright), US patent 4,598,862 (Rice), US patent 4,615,467 (Grogan et al.), and US patent 5,364,031 (Tamiguchi et al.).

It is to be understood that a person skilled in the art can choose the appropriate presentation form, as well as its method of preparation, on the basis of his/her general knowledge, taking into account the nature of the constituents used, for example, their solubility in the vehicle, and the application envisaged for the composition.

[Use and Process] The present invention also relates to a cosmetic use of the composite particle according to the present invention. In one embodiment, the composite particle according to the present invention may be applied onto a keratin substance such as skin, scalp and/or lips, preferably the skin. Thus, the composite particle and the composition according to the present invention can be used for a process, preferably cosmetic process for the skin. The use according to the present invention may be intended for absorbing ultraviolet light, and/or for protecting a keratin substance, especially of a human, from ultraviolet radiation. It is well known in the art that protection of the keratin substance from ultraviolet radiation results in anti-ageing, anti-wrinkle, and moisturizing effects. Accordingly, the composition of the present invention can further constitute a composition intended for anti-ageing, anti-wrinkle and/or moisturizing effects.

The process or cosmetic use for a keratin substance such as skin, according to the present invention comprises, at least, the step of applying onto the keratin substance the composite particle or the composition according to the present invention. The present invention can also relates to a method of protecting a keratin substance from ultraviolet radiation comprising applying to the keratin substance the composite particle or the composition according to the present invention, as well as a method of absorbing ultraviolet light comprising applying onto a keratin substance the composite particle or the composition according to the present invention and subjecting the keratin substance to ultraviolet light. These methods can be defined as non-therapeutic methods. EXAMPLES

The present invention will be described in a more detailed manner by way of examples. However, these examples should not be construed as limiting the scope of the present invention. The examples below are presented as non-limiting illustrations in the field of the present invention.

[Examples 1-5 and Comparative Examples 1-2]

The components shown in Table 1 were subjected to a hybridizer process using a hybridizer machine to obtain a composite particle according to Examples 1-5 and Comparative Examples 1-2. The numerical values for the amounts of the components shown in Table 1 are all based on "% by weight" as active raw materials.

Table 1

PS/PMMA: Styrene Acrylates Copolymer (Sunspheres marketed by Rohm and Haas)

Silica: Cosmo 30 marketed by JGC Catalyst & Chemicals Ltd.

PMMA: Methyl Methaerylate Crosspolymer (MR-7GC marketed by Soken in Japan)

Silicon resin: Polymethylsilsesquioxane (Tospearl 145A marketed by Momentive Performance Material)

Isostearic acid-treated TiOi: MT- 1 OEX marketed by Tayca in Japan

Avobemsone-treated Ίι^'Ο^, HXMT-100XA marketed by Tayca in Japan

(1) : Hydrogenated styrene-ethylene butylene-styrene triblock copolymer (I) (Kraton Gl 657M marketed by Kxaton Polymers)

(2) : Hydrogenated styrene-ethylene/butyleiie-styrene triblock copolymer (2) (Kraton GI 51 marketed by Kraton Polymers) PE: Polyethylene (Flo-beads CL8007 marketed by Sumitomo Seika)

The detailed conditions of the hybridizer process are summarized in Table 2. After the hybridizer process, sieving was performed with an opening size of 212 μπι and/or 106 μπι in order to remove Hydrogenated Styrene/Butadiene Copolymer (1) and (2) which did not react with or coat the particles.

Table 2

Hybridizer NHS-1 : A equipped with a high-speed rotor having a plurality of blades in a chamber with air circulation in dry conditions, marketed by Nara Machinery Co., Ltd. in Japan

Noblita 130: Latest mechano fusion machine for Hosokawa Micron Corporation, having a plurality of blades in a chamber without air circulation in dry condition

Output Amount: Amount of composite powder obtained after the sieving

(Coating Amount)

Each of the composite particles according to Examples 1 and 2 was filled in a column, and was eluted with hexane to extract each of Hydrogenated Styrene/Butadiene Copolymer (1) and (2), respectively. Thus, the coating amount of the extracted Hydrogenated

Styrene/Butadiene Copolymer (1) or (2) was determined using a sequential solid phase extraction column as an amount of hydrocarbon. The coating amount of each of

Hydrogenated Styrene/Butadiene Copolymer (1) and (2) in each of the composite particles according to Examples 1 and 2, relative to the total weight of the composite particle, is as follows.

[Evaluations]

The composite particles obtained by Examples 1-5 and Comparative Examples

evaluated as follows.

{SEM Observations} The composite particles obtained by Examples 1-5 and Comparative Examples 1-2 were observed by using SEM (Scanning Electron Microscope) with Hitachi S-4800. The initial shape of the core particle was spherical. Thus, it was observed whether the composite particles obtained by Examples 1-5 and Comparative Examples 1-2 were spherical. The results are shown in Table 3. The shape of the particle obtained by Comparative Example 2 was not spherical but was like a plate.

{UV Absorption}

Absorbance of UV waves of each of the composite particles obtained by Examples 1-5 and Comparative Examples 1-2 was measured by use of a UV VIS spectrophotometer type V-550 (JASCO, Japan) as follows. A solvent was prepared by mixing isododecane and polyhydroxystearic acid such that the concentration of polyhydroxystearic acid was 3 wt%.

Each of the composite particles obtained by Examples 1-5 and Comparative Examples 1-2 was dispersed in the above solvent by using ultrasonic waves for 1 minute at room

temperature to obtain a sample, such that the concentration of the composite particles in the sample was 0.1 wt%. If agglomerates were still present, the ultrasonic treatment was repeated.

The obtained sample was put into a quartz cell having a 2-mm light pathway. The UV absorbance of the sample in the wavelength of from 280 to 400 nm was measured by use of a UV VIS spectrophotometer type V-550 (JASCO, Japan). The integral value of the UV absorbance in the wavelength range of from 280 to 400 nm was calculated as "UV

Absorption".

The results are shown in Table 3 in the column of "UV Absorption". A high value of "UV Absorption" indicates high UV protection performance.

{Stability}

(Filtration Test)

The stability of each of the composite particles obtained by Examples 1-5 and Comparative Examples 1-2 was tested as follows.

A solvent was prepared by mixing water and sodium lauryl sulfate such that the concentration of sodium lauryl sulfate was 1 wt%.

Each of the composite particles obtained by Examples 1-5 and Comparative Examples 1-2 was dispersed in the above solvent by using ultrasonic waves for 30 minutes at 30-40°C to obtain a sample, such that the concentration of the composite particles in the sample was 0.5 wt%. If agglomerates were still present, the ultrasonic treatment was repeated.

The obtained sample was subjected to a centrifugation at 5250 rpm (approximately 2900 G) for 5 minutes, and the supernatant was separated. The supernatant was filtrated with a filter of conical shape with a bottom circle having a diameter of 33 mm, and a top circle with a diameter of 0.22 μηι (Millipore SLGP033NB).

The filtrated supernatant was put into a quartz cell having a 2-mm light pathway. The UV absorbance of the sample in the wavelength range of from 280 to 400 nm was measured by use of a UV/VIS spectrophotometer type V-550 (JASCO, Japan).

The results are shown in Table 3 in the column of "Filtration Test". A high value of

"Filtration Test" indicates that more UV filters detached from the composite particles (unstable).

(Morphology Test)

A solvent was prepared by mixing water and disodium stearoyl glutamate such that the concentration of disodium stearoyl glutamate was 1 wt%.

Each of the composite particles obtained by Examples 1-5 and Comparative Examples 1-2 was dispersed in the above solvent by using ultrasonic waves for 30 minutes at 30-40°C to obtain a sample, such that the concentration of the composite particles in the sample was 1 wt%. If agglomerates were still present, the ultrasonic treatment was repeated.

The obtained sample was diluted with ethanol such that the concentration of the composite particles became 0.1 vol%. The composition of the diluted sample was 0.1 vol% particles/0.1 vol% disodium stearoyl glutamate/about 10 vol% water/about 90 vol% of ethanol.

The diluted sample was put on a silicon wafer and observed by using SEM (Scanning Electron Microscope) with Hitachi S-4800.

The results are shown in Table 3 in the column of "Morphology Test". "Good" means that Ti0₂ particles firmly attached to the particles (stable), while "Poor" means that Ti0₂ particles detached from the particles (unstable).

Table 3

It is clear from Tables 1-3 that the composite particles according to Examples 1-5 coated with a hydrophobic block copolymer are more stable than those according to Comparative Example 1 (uncoated) or Comparative Example 2 (coated with polyethylene: a hydrophobic homopolymer).

Thus, the UV filters on the composite particles according to Examples 1-5 firmly attached to the surface of the composite particles, and did not detach from the surface of the composite particles even in the presence of the anionic surfactants.

On the other hand, the UV filters on the composite particles according to Comparative Examples 1-2 did not firmly attach to the surface of the composite particles, and did detach from the surface of the composite particles in the presence of the anionic surfactants.

[Example 6 and Comparative Examples 3-4]

A sun-care formulation in the form of an O/W emulsion was prepared by mixing the components shown in Table 4. The numerical values for the amounts of the components shown in Table 4 are all based on "% by weight" as active raw materials.

Table 4

[In Vitro SPF Value Evaluation] (Initial)

Each of the sun-care formulations according to Example 6 and Comparative Examples 3 was applied onto a PMMA plate in an amount of 0.75 mg/cm², and the SPF value of the sample was measured by an SPF analyzer UV-2000S. The results are shown in Table 4. (After Washing)

The sample as prepared above was washed with running tap water for 1 minute. The SPF value of the washed sample was measured by an SPF analyzer UV-2000S. The results are shown in Table 4.

It is clear from Table 4 that the composite particles according to Example 1 and Comparative Example 1 can enhance the UV filtering properties of the formulation, and that the UV filtering properties provided by the composite particles according to Example 1 are more stable than those according to Comparative Example 1. This is because the UV filters on the composite particles according to Example 1 firmly attached to the surface of the composite particles after being washed and the composite particles kept their UV filtering function even after being washed, while the UV filters on the composite particles according to Comparative Example 1 detached from the surface of the composite particles after being washed and the composite particles could not keep their UV filtering function after being washed.

Claims

A composite particle, comprising:

(a) at least one core particle,

wherein

The composite particle according to Claim 1, wherein the mean particle size of the (a) core particle is 100 nm or more, preferably 200 nm or more, and more preferably 300 nm or more, and/or 50 μιη or less, preferably 20 μπι or less, and more preferably 10 μηι or less.

The composite particle according to Claim 1 or 2, wherein the (a) core particle comprises at least one inorganic material and/or at least one organic material, preferably at least one organic material.

The composite particle according to any one of Claims 1 to 3, wherein the (b) solid UV filter is selected from inorganic solid UV filters, preferably is selected from the group consisting of silicon carbide, metal oxides, and mixtures thereof, and more preferably is titanium oxide.

The composite particle according to any one of Claims 1 to 4, wherein the (b) solid UV filter has a mean particle size of from 1 nm to 200 nm, preferably from 5 nm to 100 nm, and more preferably from 10 nm to 50 nm.

The composite particle according to any one of Claims 1 to 5, wherein the weight ratio of the (a) core particle(s) to the (b) solid UV filter(s) is from 10:90 to 90: 10, preferably from 20:80 to 80:20, and more preferably from 30:70 to 70:30.

The composite particle according to any one of Claims 1 to 6, wherein the (c) hydrophobic block copolymer has a recovery ratio of 50% or more, preferably 60% or more, and more preferably 70% or more.

The composite particle according to any one of Claims 1 to 7, wherein the (c) hydrophobic block copolymer is a hydrocarbon-based block copolymer, preferably comprising at least one styrene block and at least one block comprising units chosen from butadiene, ethylene, propylene, butylene and isoprene or a mixture thereof, which are optionally hydrogenated.

The composite particle according to any one of Claims 1 to 8, wherein the (c) hydrophobic block copolymer is chosen from styrene-ethylene/propylene, styrene- ethylene/butadiene, styrene-ethylene/butylene, styrene-ethylene/isoprene diblock copolymers, which are optionally hydrogenated, and styrene-ethylene/propylene- styrene, styrene-ethylene/butadiene-styrene, styrene-ethylene/butylene-styrene, styrene-isoprene-styrene and styrene-butadiene-styrene triblock copolymers, which are optionally hydrogenated, and mixtures thereof.

10. The composite particle according to any one of Claims 1 to 9, wherein the amount of the second coating layer is from 0.01 to 30% by weight, preferably from 0.1 to 20% by weight, and more preferably from 0.3 to 15% by weight, relative to the total weight of the composite particle.

11. A composition, preferably cosmetic composition comprising a composite particle according to any one of Claims 1 to 10.

12. A cosmetic use of a composite particle according to any one of Claims 1 to 10.

13. A process, preferably cosmetic process comprising

applying a composite particle according to any one of Claims 1 to 10, or a cosmetic composition according to Claim 11 onto a keratin substance.

14. A method for preparing a composite particle, comprising a step of subjecting:

(a) at least one core particle;

(b) at least one solid UV filter; and

(c) at least one hydrophobic block copolymer

to a mechanochemical fusion process.