JP2002527531A - Stable oil-in-water emulsion, process for its preparation and its use in cosmetics and dermatology - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention relates to a method for producing an emulsion, comprising: a droplet of an oil phase having an average particle size of less than 20 microns, wherein the oil phase comprises at least 15% by weight relative to the total weight of the emulsion, and comprising a main portion consisting of C ₃ -C ₆ carboxylic acid monomer or its anhydride having an olefinic unsaturation, at least one copolymer composed of a small amount portion consisting of acrylic acid fatty chain ester monomer, and a surfactant And an emulsion containing an oil phase dispersed in an aqueous phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a stable oil-in-water comprising oily droplets having an average particle size of less than 20 microns and comprising at least 15% by weight of an oil phase and at least one copolymer of a fatty chain carboxylic acid ( O / W) regarding emulsions. The invention also relates to a method for preparing such an emulsion and to its use in cosmetic and / or dermatology.

[0002]

[Prior art]

For a variety of reasons that are particularly relevant to the substantial feel, such as comfort and freshness during use, cosmetic compositions usually take the form of an oil-in-water emulsion containing an oil phase uniformly dispersed in an aqueous phase. In conventional emulsions, the size of the droplets making up the fatty phase is generally larger than a few tens of microns. Such emulsions may have poor cosmetic properties (greasy feel) and physical properties (stability). Insufficient stability is reflected in the appearance of a phenomenon called separation (phase separation) between the water phase and the oil phase of the emulsion. Such instability is disadvantageous for emulsion storage.

In order to obtain a stable emulsion, it is necessary to add an emulsifier located at the interface between the water phase and the oil phase (ie, a surfactant) to the emulsion. However, the presence of surfactants has several disadvantages, in particular, usually the emulsions need to be prepared under warm conditions, which in particular limits the properties of the active agents introduced into the emulsion. Resulting in. In particular, this method eliminates the use of heat-sensitive actives. Thus, there has been a need to eliminate surfactants. In addition, surfactants can cause irritation, especially in people with sensitive skin.

[0004]

Problems to be Solved by the Invention and Means for Solving the Problems

Applicants have unexpectedly found that emulsions containing a large amount of oil phase and no surfactant have oil droplets with an average particle size of less than 20 microns, and that monoolefin unsaturated It has been found that it is prepared by using a copolymer composed of a main part composed of a C ₃ -C ₆ carboxylic acid monomer or an anhydride thereof and a small part composed of an acrylic acid fatty chain ester monomer.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION

The subject of the present invention is that the droplets of the oil phase have an average particle size of less than 20 microns, this oil phase comprises at least 15% by weight relative to the total weight of the emulsion, and that the aqueous phase comprises a monoolefinically unsaturated C features and ₃ -C ₆ carboxylic acid monomer or main portion consisting of the anhydrides, include at least one copolymer composed of a small amount portion consisting of acrylic acid fatty chain ester monomer, and that it does not contain a surfactant An emulsion containing an oil phase dispersed in an aqueous phase.

As is generally accepted, the use of fatty chain polymers to stabilize emulsions is well known, but with too much oil the emulsion tends to become unstable over time. ing. According to the present invention, since the oily droplets have a sufficiently small size, good stability can be obtained even in the presence of a large amount of oil. Furthermore, these oily droplets are dispersed, i.e. substantially all have the same size, which is different from prior art emulsions in which the particles of the dispersed phase usually have very diverse sizes. .

[0007] The copolymers used in the emulsions of the present invention have the advantage of stabilizing the emulsion as well as gelling it over commonly used surfactants. In addition, unlike surfactants, it does not penetrate the skin,
The risk of inflammation can be significantly reduced.

[0008] The copolymer used in the emulsion according to the present invention is prepared by polymerizing a predetermined amount of a monoolefinically unsaturated carboxylic acid monomer or an anhydride thereof with a small amount of an acrylic acid fatty ester monomer. The term "fatty chain" means a straight or branched alkyl group containing 8 to 30 carbon atoms.

The amount of carboxylic acid monomer or its anhydride, calculated on the total weight of the two monomers, is preferably in the range from 80 to 98% by weight, in particular from 90 to 98% by weight, while acrylic acid The ester is 2 to 20% by weight, in particular 1 to 1
It is present in an amount ranging from 0% by weight.

Preferred carboxylic acid monomers have the following formula (I):

Embedded image [Wherein, R represents a hydrogen atom, a halogen atom, a hydroxyl group, a lactone group, a lactam group, a cyan (-C = N) group, a monovalent alkyl group, an aryl group, an alkylaryl group, an aralkyl group, or a cyclic aliphatic group. Is shown]].

[0011] Particularly preferred carboxylic acid monomers are selected from acrylic acid and methacrylic acid or mixtures thereof.

The acrylic acid fatty ester monomer is preferably of the following formula (II):

Embedded image Wherein R ₁ is selected from the group consisting of a hydrogen atom, a methyl group and an ethyl group,
And R ₂ is a C ₈ -C ₃₀ alkyl group].

Particularly preferred ester monomers are those in which R ₁ is a hydrogen atom or a methyl group and R ₂ is a C ₁₀ -C ₂₂ alkyl group.

The copolymer used in the emulsion according to the invention is present in an amount ranging from 0.1 to 4% by weight, preferably from 0.2 to 1% by weight, based on the total weight of carboxylic acid monomer and acrylate monomer. Crosslinking can be carried out arbitrarily using the crosslinking agent used. The crosslinker can be chosen in particular from polymerizable monomers comprising a polymerizable CH ₂ ＣC— group and at least one further polymerizable group, whose unsaturated bonds are not bonded to one another. .

[0015] These copolymers are described in EP-A-0 268 164 and are obtained according to the preparation methods described therein.

Particularly used copolymers are Brookfield in a 2% aqueous solution and at 25 ° C.
Using a viscometer, 5000 cPs (5 Pa.s) or less, especially about 3000 cPs (
3 Pa. s) and a viscosity measured in particular by Perich from Goodrich.
len TR1, Pemulen a TR2 and Carbopol products sold under the trade name of 1382 or acrylate / C ₁₀ -C ₃₀ alkyl acrylate copolymers as well as mixtures thereof.

The copolymer is used in the emulsion according to the invention in a concentration ranging from 0.1 to 4% by weight, in particular from 0.1 to 2% by weight, based on the total weight of the emulsion.

The emulsion according to the present invention does not contain a surfactant. Thus, by the absence of surfactant, the emulsion has the advantage of allowing the uptake of heat-sensitive active agents and the advantage that it is not irritating to the skin, especially sensitive skin.

Further, the average particle size of the droplets in the oil phase is less than 20 microns, preferably in the range of 0.5 to 15 microns, as measured on the basis of the value obtained by the laser scattering method. Due to the fineness of these oily droplets, the emulsion obtained has particularly satisfactory sensory and visual properties.

The nature of the oil phase of the emulsion according to the invention is not critical. The oily phase can thus be a fatty substance, especially an oil, commonly used in cosmetics and dermatology.

Among the oils that can be used in the emulsions of the invention, in particular, for example, vegetable oils (jojoba oil, avocado oil), mineral oils (vaseline), synthetic oils (ethylhexyl palmitate, isopropyl myristate), volatile silicones Oils (cyclomethicone), non-volatile silicone oils and fluoro oils can be mentioned. Other fatty substances that can be present in the oil phase are, for example, fatty acids, fatty alcohols and waxes (liquid jojoba wax).

The oil phase of the emulsion is 15 to 45% by weight relative to the total weight of the emulsion
, More preferably from 20 to 30% by weight.

The emulsion according to the invention can be used in any field where such a pharmaceutical form is advantageous, in particular in the fields of cosmetics and dermatology. When making up the cosmetic and / or dermatological composition, it may advantageously comprise a physiologically acceptable medium, ie a medium compatible with the skin, mucous membranes, nails and / or hair.

The emulsions which are the subject of the present invention can find application in many cosmetic and / or dermatological treatments for the skin, mucous membranes and hair, including the scalp, in particular for the protection of the skin and / or mucous membranes, Care, washing and / or makeup, hair protection, care and / or washing, and / or skin, hair and / or mucous membranes (lips)
Can find application in the therapeutic treatment of

Emulsions according to the invention can be used, for example, as facial care products and / or cleansing products in the form of creams or emulsions, or as make-up products (for skin and lips) by incorporating fillers, pigments or dyes. Can be used.

Thus, a further subject of the invention is a cosmetic of the above-mentioned emulsions for treating, protecting, caring and / or cleaning the skin, mucous membranes and / or hair, and / or for making up the skin and / or mucous membranes Purpose.

Another subject of the invention is the use of the above-mentioned emulsions for producing a dermatological composition for treating and / or protecting the skin, mucous membranes and / or hair.

In addition, according to well-known techniques, the emulsions of the present invention can be used with hydrophilic or lipophilic activators, preservatives, antioxidants, fragrances, solvents, fillers, screening agents, dyes, basic agents (triethanolamine) Or they may contain acidic agents, as well as adjuvants commonly used in cosmetics or dermatology, such as lipid vesicles. These adjuvants are used in cosmetic or dermatological customary proportions, for example from 0.01 to 30% relative to the total weight of the emulsion, depending on the nature of the emulsion in the water or oil phase, or in vesicles. Introduced inside. These adjuvants and their concentrations must not alter the properties desired in the emulsion.

If it is desired to obtain a poorly flowable emulsion, one or more gelling agents such as clay, polysaccharide gum (xanthan gum), carboxyvinyl polymer or carbomer can be added thereto. These gelling agents may comprise from 0.1 to 10%, preferably from 0.1 to 5%, more preferably from 0 to 10%, based on the total weight of the composition.
. Used in concentrations ranging from 1 to 3%.

The emulsions of the present invention can optionally be free of solvents. It is also a relatively non-aggressive or non-irritating emulsion that can be used by people with sensitive skin. However, if desired, solvents can be included, especially lower alcohols containing 1 to 6 carbon atoms, especially ethanol. The amount of solvent can range up to 30% based on the total weight of the composition.

The emulsion according to the invention can be prepared by any means suitable for obtaining oily droplets having a size of less than 20 microns. According to a preferred embodiment of the present invention, these are prepared using a microporous membrane, and this technique is used to obtain droplet sizes particularly suitable for the purpose of the present invention, in particular for a given size uniformity. Makes it possible to obtain oily droplets of dust. Such techniques are described, for example, in EP-A-546174.
No., published in Japanese Unexamined Patent Publication No.

Thus, a further subject of the present invention is a process for preparing the above-mentioned emulsions, which comprises a pressure above the critical pressure of between 0.1 and 5 μm, preferably between 0 and 5 μm.
. Through a hydrophilic porous glass membrane with an average pore size in the range of 3 to 3 μm,
It consists of introducing the oil phase under pressure into the aqueous phase containing the copolymer.

Preferably, the membrane comprises an aqueous phase of the composition according to the invention of about 2 per liter.
Pretreatment in gram containing demineralized water under vacuum and using ultrasound, the treatment lasting about 1 hour.

The expression “critical pressure” means the minimum pressure required to introduce a dispersed phase into a continuous phase through a porous glass membrane of a given pore size. The critical pressure (expressed in kPa) is given by the following formula: Pc = 4γ _OW cos θ / D _{m wherein} γ _OW is the interfacial tension (mN / m), θ is the contact angle (rad), and D _m is the porosity. Average particle size (μm) of pores of the functional glass film].

In the method according to the invention, the pressure used is preferably Pc + 20 kPa.

For example, a membrane with a pore size in the range 0.1 to 5 μm can be used, preferably using a pressure in the range 350 to 30 kPa (3.5 to 0.3 bar). Preferably, the membrane used is 0.3 μm, 0.7 μm or 2.8.
With a pore size of μm, 220 to 320 kPa (2.2 to 3.2 bar), 140 to 200 kPa (1.4 to 2 bar) and 3 respectively.
A pressure of 0 to 70 kPa (0.3 to 0.7 bar) is used.

The following examples illustrate the invention. In this example, the percentages are given on a weight basis.

[0038]

【Example】

 Example 1: Phase A Pemulen TR2 0.75% Triethanolamine 0.75% Preservative 0.2% Demineralized water Amount to 100% total Phase B Volatile silicone oil (cyclopentasiloxane) 20%

Preparation: A membrane with a pore size of 0.7 μm is immersed in 1 liter of demineralized water containing 2 g of phase A and left under vacuum and ultrasound for 1 hour. After this treatment of the membrane, phase A is pumped through the membrane. When the phase B is 170 kPa (
It is left under pressure up to a critical pressure of 1.7 bar). Phase B was added at 190 kPa (1.
Emulsify in phase A under a pressure of 9 bar).

Very fine emulsions, which are very comfortable when applied, are obtained.

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Claims (13)

[Claims] 1. An emulsion comprising an oil phase dispersed in an aqueous phase, wherein the oil phase droplets have an average particle size of less than 20 microns, wherein the oil phase is at least based on the total weight of the emulsion. form a 15 wt%, and comprised of the aqueous phase is a main portion consisting of mono-olefinically unsaturated C ₃ -C ₆ carboxylic acid monomer or its anhydride, with a little portion of acrylic acid fatty chain ester monomer An emulsion comprising at least one copolymer and no surfactant. 2. The amount of the carboxylic acid monomer or its anhydride in the copolymer ranges from 80 to 98% by weight and the amount of the ester monomer ranges from 20 to 2% by weight relative to the total weight of the two monomers. The emulsion according to claim 1, characterized in that: 3. The carboxylic acid monomer of the formula (I): Wherein R represents a hydrogen atom, a halogen atom, a hydroxyl group, a lactone group, a lactam group, a cyano group, a monovalent alkyl group, an aryl group, an alkylaryl group, an aralkyl group or a cycloaliphatic group. And the ester monomer has the following formula (II): Wherein R ₁ is selected from the group consisting of a hydrogen atom, a methyl group and an ethyl group,
And R ₂ is a C ₈ -C ₃₀ alkyl group.] The emulsion according to claim 1, wherein 4. The carboxylic acid monomer is selected from acrylic acid, methacrylic acid and a mixture thereof, and the ester monomer is such that R ₁ is a hydrogen atom or a methyl group and R ₂ is a C ₁₀ -C ₂₂ alkyl group. An emulsion according to claim 3, characterized in that it is selected from monomers of formula (II): 5. The copolymer according to claim 1, wherein the copolymer is present in an amount ranging from 0.1 to 4% by weight, based on the total weight of the emulsion. The emulsion according to any one of the above. 6. An emulsion according to claim 1, wherein the average particle size of the oil phase droplets is in the range of 0.5 to 15 microns. 7. The emulsion according to claim 1, wherein the oil phase comprises 15 to the total weight of the emulsion.
Emulsion according to one of the claims 1 to 6, characterized in that it is present in an amount of from 45 to 45% by weight, preferably 20 to 30% by weight. 8. Emulsion according to claim 1, which constitutes a cosmetic and / or dermatological composition. 9. A hydrophilic activator, a lipophilic activator, a preservative, an antioxidant, a fragrance,
9. The method according to claim 1, further comprising at least one additive selected from a solvent, a filler, a sunscreen agent, a pigment, a dye, a basic agent, an acid agent, a lipid vesicle and a gelling agent. The emulsion according to claim 1. 10. Treatment, protection, care and / or treatment of skin, mucous membrane and / or hair
Or a cosmetic use of the emulsion according to any one of claims 1 to 9 for washing and / or making up skin and / or mucous membranes. 11. Use of the emulsion according to claim 1 for the manufacture of a dermatological composition for treating and / or protecting skin, mucous membranes and / or hair. 12. An oily phase comprising a copolymer at a pressure above the critical pressure through a hydrophilic porous glass membrane with an average pore size in the range of 0.1 to 5 μm, preferably 0.3 to 3 μm. Consisting of being introduced under pressure into the aqueous phase,
A method for producing the emulsion according to any one of claims 1 to 9. 13. The method according to claim 12, wherein the pressure is in the range of 30 to 350 kPa.