FR3079745A1 - OIL EMULSION IN WATER FORMING SHAPE MEMORY CREAM - Google Patents

Abstract

The emulsion comprises, especially as a rheology modifier, a copolymer of acrylate and / or methacrylate monomers having acrylate and / or methacrylate side chains esterified with a polyalkoxylated C 12 -C 30 fatty alcohol, for example the copolymer of acrylates and methacrylates. beheneth-25, one or more emulsifiers, preferably of sorbitan (poly) alkoxylated type and (poly) esterified with a C 8 -C 30 fatty carboxylic acid and / or a sorbitan and / or sorbitol (poly) type emulsifier esterified with by means of a C8-C30 fatty carboxylic acid, and a number of esters, natural or synthetic, of C12-C30 fatty alcohol in the form of an oil, in precise proportions and pH, making it possible to obtain an original texture similar to an opaque aqueous balm with shape memory.

Description

OIL IN WATER EMULSION FORMING A MEMORY CREAM

TECHNICAL AREA

The present invention relates to an oil-in-water (O / W) emulsion forming a shape memory cream and a process for manufacturing this emulsion.

It relates more particularly to the field of cosmetics and dermopharmacy, but can be applied to any other field using this type of formula, such as the food field or that of paints.

STATE OF THE ART

A shape memory cream is a low-viscosity cream, most often a transparent gel or a continuous-water phase emulsion (O / W), the smooth shape of which deforms after gripping and then re-forms over time, regaining its smooth texture as if it had not been used (the surface of the pot becoming flat again). When a small force is applied to the formula, at the time of sampling in its jar, then by kneading and / or simply via application to the skin, the cream spreads easily. Then, over time, a cream fdm is reformed on the skin conforming to the application site with a "filling" and "lifting" effect.

For this, an agent capable of modifying the rheology of the emulsion is used, that is to say capable of modifying the flow or the deformation of the formula under the effect of the stresses which are applied to it.

For a shape memory cream, the rheology modifying agent must contribute to obtaining a final formula in which the shear strength and therefore the viscosity can change very strongly between rest and use.

This technical effect can for example be obtained by using a copolymer functionalized by the presence of different side chains capable of interacting with each other under certain conditions. Such an interaction, in addition to a certain degree of crosslinking, will give the copolymer a three-dimensional network structure and therefore give the formula a high shear rate, and when this network structure is modified by the application of a external force, the shear rate of the formula will greatly decrease.

A copolymer of acrylate and / or methacrylate monomers has for example been proposed, having acrylate and / or methacrylate side chains esterified in particular with a fatty alcohol (polyalkoxylated (- (O- (CH2) n) n -OC _n H211 + i) In an aqueous or ionic solution, the anionic acrylate and / or methacrylate chains will repel each other while the long alkoxylated fatty alcohol chains will combine to form micelles, which will make it possible to create a three-dimensional network of weak reversible bonds. , together with the swelling of the emulsion particles themselves.

A copolymer of this type (INCI name: Acrylates / Beheneth-25 Methacrylate Copolymer) is sold for example under the trade name Volarest ™ FU by the company CRODA, Aculyn ™ 28 Polymer and Aculyn ™ 28P Polymer by the company DOW CHEMICAU, Rheostyl ™ 90 N and Rheostyl ™ 10 SH by the company COATEX, Novethix ™ L-10 Polymer by the company Lubrizol, Euroflow 100 by the company EOC Surfactants or Tinovis GTC by the company BASF. This copolymer comprises a mixture of anionic acrylate and methacrylate monomers, with some of the methacrylates esterified to form fatty side chains of beheneth-25, that is to say side chains of formula - (O-CH2-CH2) 25- O- (CH2) 2i-CH3, with n = 2 (a polyethoxylated fatty alcohol), n '= 25 on average and n ”= 21), and some of the acrylates and / or methacrylates in the form of simple esters (C1- C4). The proportion of beheneth-25 side chain metacrylate monomer is generally less than 10% by weight relative to the total weight of the other monomers forming the copolymer.

Typically an O / W emulsion type memory cream, known from the state of the art and comprising this copolymer, will be formed from at least:

- An aqueous phase containing the copolymer, one or more humectants and one or more emulsifiers;

- a fatty phase containing one or more emollients and one or more emulsifiers;

- optionally active ingredients distributed in the appropriate phase according to their hydrophilic or hydrophobic nature;

- a pH adjuster, and

- optionally one or more preservatives, antioxidant, antifungal agents, colorants, perfumes or other suitable additive;

with the weight of emollient (forming the base of the fatty phase) generally representing approximately 10% of the final weight of the formula. The emollients used are generally fatty alcohol esters of natural (vegetable) or synthetic origin in the form of oils (fatty substance fluid at room temperature). These emulsifiers are also chosen so as to obtain a “soft” (elastic) “shooting” cream having a viscosity of approximately 75,000 Cps (10 ^-3 Pa.s) ± 10%.

STATEMENT OF THE INVENTION

The object of the present invention is to propose a new formula for an O / W emulsion type memory cream having original characteristics in terms of rigidity and elasticity.

According to a first object, the present invention provides an O / W type emulsion, with shape memory, constituted in% by weight relative to the total weight of the emulsion of:

- in the aqueous phase:

o 0.2 to 1% of a copolymer of acrylate and / or methacrylate monomers having acrylate and / or methacrylate side chains esterified with a polyalkoxylated C12-C30 fatty alcohol, as a rheology modifier;

o 3.00% to 15.00% of one or more humectants;

ο 1% to 5% of one or more emulsifiers;

- in the fatty phase:

ο Ι, θθ% to 5.00% of one or more esters, natural or synthetic, of fatty alcohol C12-C30 in the form of oil, as an emollient;

- Water for the aqueous phase in an amount sufficient by weight so that the total weight of the composition is 100%;

- a pH adjuster in quantity by weight such that the pH of the emulsion is between 6.00 and 7.00; and

- optionally one or more water-soluble or liposoluble active ingredients in the appropriate phase, preservatives, antioxidant, antifungal agents, dyes, perfumes, glitter or other additive.

In the present description, all the weight percentages indicated are relative to the total weight of the emulsion, unless otherwise specified. All the physical measurements indicated are taken at room temperature (+/- 20 ° C). The viscosity measurements are established with a Brookfield DV-I Prime viscometer (SP93 needle, speed 2.5 t / m, 1mm, at 25 ° C).

According to the invention, the term “fatty alcohol” is intended to mean a C12-C30 alcohol, preferably C16C26, more preferably C18-C22.

According to the invention, the term “fatty carboxylic acid” is intended to mean a C8C30 carboxylic acid.

The formula according to the invention differs from the prior art in addition to the choice of the nature of the rheology modifier, of the emulsifiers and of the emollient, by the fact that it contains only a very small amount of phase. emollient fat, between 1 and 5% relative to the total weight of the composition.

Thanks to this particular formula, an opaque shape memory cream which has no elasticity and which breaks as if it were hard. Its viscosity is high by at least 100,000 Cps (10 ^-3 Pa.s) measured at room temperature. You can take real pieces. The cream has the consistency of a balm but which instead of being traditionally oily / waxy would be aqueous. It also has the characteristics of a shape memory cream: it resumes its smooth shape on the surface after removing a piece (after a few hours) and softens so that it can be applied to the skin. on which it will then form a smoothing film hugging the relief.

Preferably according to the invention, the rheology-modifying copolymer is a copolymer of acrylates and metacrylates with a polyalkoxylated fatty alcohol having on average from 15 to 35 alkoxy units, more preferably from 20 to 30 alkoxy units.

Preferably also the copolymer is a copolymer of polyethoxylated and / or polypropoxylated fatty alcohol acrylates and metacrylates of C12-C30 (the alkoxy units are ethoxylated and / or propoxylated units), preferably polyethoxylated, and more preferably the copolymer is the copolymer of beheneth 25 acrylates and methacrylates as described above, preferably still Volarest ™ FL, with a content of side chains methacrylates esterified with beheneth 25 in% by weight relative to the weight of the side chains not esterified (acrylates or methacrylates) is less than 10%.

The content of copolymer in the emulsion according to the invention is preferably from 0.3 to 0.9%, more preferably from 0.5 to 0.75% by weight relative to the total weight of the emulsion.

Preferably according to the invention, the first emulsifier of the aqueous phase is a polyethoxylated emulsifier, preferably a polyethoxylated sorbitan, several of the alcohol sites, preferably all of the sites, being ethoxylated and comprise several ethoxy units, and monoesterified with l using fatty carboxylic acid C8-C30, preferably in position 6 on the primary alcohol.

Preferably, according to the invention, the emulsifier is of the sorbitan (poly) alkoxylated and (poly) esterified type with a fatty C8-C30 carboxylic acid and / or of the sorbitan and / or sorbitol (poly) esterified type using of a C8-C30 fatty carboxylic acid.

More preferably, the sorbitan (poly) alkoxylated and (poly) esterified type emulsifier with a fatty C8-C30 carboxylic acid is polyoxyethylene sorbitan monostearate of the following formula (INCI name: Polysorbate 60):

The content of first emulsifier is preferably from 1 to 5%, more preferably from 2 to 3% by weight relative to the total weight of the emulsion.

Preferably, the sorbitan and / or sorbitol (poly) esterified emulsifier using a fatty C8-C30 carboxylic acid is non-alkoxylated, more preferably based on sorbityl and / or mono-esterified sorbitan. , more preferably still consisting of a mixture of sorbityl stearate and sorbityl laurate. This type of non-alkoxylated emulsifier is used for the stability of the emulsion and contributes to obtaining the shape memory effect.

The content of sorbitan and / or sorbitol (poly) esterified type emulsifier using a C8-C30 fatty carboxylic acid is preferably 1 or 3% by weight relative to the total weight of the emulsion, preferably 1 to 2% by weight.

Preferably, the formula according to the invention contains the three preferred emulsifiers in the following proportions (in% by weight relative to the total weight of the emulsion):

- 0.5 to 3% by weight of polyoxyethylene sorbitan monostearate;

- 0.5 to 1.5% by weight of sorbitan stearate, and

- 0.5 to 1.5% by weight of sorbityl laurate.

Polyoxyethylene sorbitan monostearate (INCI name: Polysorbate 60) is sold under the trade name Tween ™ 60 by the company Croda.

A mixture of sorbitan stearate and sorbityl laurate with substantially equal weight contents is sold under the trade name ARLACEL ™ LC by the company Croda.

Preferably, the humectant (s) used are according to the invention are chosen from glycol, pentylene glycol and glycerin, more preferably pentylene glycol.

Preferably the humectant content is from 3.00% to 5.00% by weight, preferably from 3.00% by weight.

Preferably according to the invention, the esters of vegetable or synthetic fatty alcohols in the form of an oil forming the emollient are polar oils of monoesters, preferably volatile, preferably aromatic, more preferably benzoate monoesters, and more preferably alcohol esters in C12-15. The benzoate monoesters are advantageously volatile oils and therefore “dry” to the touch, which will contribute to forming a cream with a light, non-greasy and non-sticky aqueous feel. A minimum presence of oil, at least 1% by weight is however necessary to form the emulsion and for the retention of shape memory and pleasant feel (the binder). The amount of oil is preferably between 1 and 3%.

Preferably, the viscosity of the cream is adjusted to at least 110,000 Cps, more preferably at least 120,000 Cps.

According to a preferred example, an emulsion comprising:

- 2.5% of Volarest ™ FL (INCI name: Acrylates / Beheneth-25 Methacrylate

Copolymer), comprising about 0.75% of the shape memory copolymer;

- 1.70% of Arlacel ™ LC (INCI name: Sorbitan Stearate (and) Sorbityl Laurate);

- 2.00% of Tween ™ 60 (INCI name: Polysorbate 60);

- 3.00% of Crodamol ™ AB (INCI name: C12-15 Alkyl Benzoate);

- 3.00% pentylene glycol;

- a pH adjuster in quantity such that the pH of the composition is between

6.10 ± 0.5;

- deionized water in sufficient quantity for a total weight of composition of

100%; and

- optionally one or more water-soluble active ingredients, preservatives, antioxidant, antifungal agents, dyes or perfumes.

According to a second object, the present invention provides a method of manufacturing the emulsion according to the first object, characterized in that it comprises the steps of:

- form an aqueous part A comprising:

o the shape memory copolymer;

o the humectant (s); and o said at least one emulsifier;

- if necessary, heat said part A so as to homogenize it in liquid form;

- form a part B comprising the emollient;

- add part B to part A;

- form an emulsion with rapid stirring;

- adjust the pH between 6 and 7 using a pH adjuster;

- optionally add one or more water-soluble or liposoluble active agents in the appropriate phase, preservatives, antioxidant, antifungal agents, dyes, perfumes, glitter or other additive.

Preferably, in the process, the formation of part A is divided into the subsequent formation of two parts A1 and A2 which are then combined, the process comprising:

- Form the part A1 comprising the shape memory copolymer and a first emulsifier;

- if necessary heat said part Al so as to homogenize it in liquid form;

- form the part A2 comprising the humectant and a second emulsifier; and

- if necessary, heat said part A2 so as to homogenize it in liquid form.

Preferably, the first emulsifier added to part A1 is the emulsifier of sorbitan type (poly) alkoxylated and (poly) esterified by a fatty C8-C30 carboxylic acid, as defined above.

Also preferably, the second emulsifier added to part A2 is the sorbitan and / or sorbitol (poly) esterified emulsifier using a C8-C30 fatty carboxylic acid, as defined above.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be better understood in the light of the following description of a nonlimiting exemplary embodiment.

For this example formula, the commercial ingredient Volarest ™ FL is used as a rheology modifier. It comprises approximately 30% of acrylate / methacrylate copolymer of Beheneth-25 in an aqueous matrix.

The commercial ingredients Tween ™ 60 and Arlacel ™ LC are used as emulsifiers. Their constituents are pure in fluid “paste” form.

The commercial ingredient Crodamol ™ AB is used as an emollient. It consists of a pure mixture of C12-15 alkyl benzoate.

Ingredient / INCI Name / Supplier Function % p / p Part A: Deionized water (Aqua) Volarest ™ FL / Acrylates / Beheneth-25 Methacrylate Copolymer / Croda Tween ™ 60 / Polysorbate 60 / Croda Rheology modifier emulsifier Qsp 100 2.50 (corresponding to approximately 0.75% of the copolymer according to the invention) 2.00 Part B: Arlacel ™ LC / Sorbitan Stearate (and) Sorbityl Laurate / Croda Pentylene Glycol emulsifier humectant 1.70 3.00 Part C: Crodamol ™ AB / C12-15 Alkyl Benzoate / Croda Emollient 3.00 Part D: Deionized water (Aqua) Sodium hydroxide 30% PH adjuster 2.00 0.20

Protocol

Weigh part A and mix. Heat part A to 75 ° C in a double boiler.

Weigh part B and mix.

Add part B to part A and stir for 30 min at 75 ° C with normal propeller stirring (= 500 rpm).

Weigh part C and heat it to 75 ° C in a double boiler.

Add part C to parts A + B with strong stator stirring (= 1000 rpm)

Adjust the pH to 6.1 +/- 0.5.

The cream obtained is white and opaque, having a high viscosity of 120,000 Cps (10 ^-3 Pa.s). It looks like a balm, solid with a flat upper surface in which you can dig using a small spatula to take a "piece" of cream. Unlike the wax-based balm, the initial form of the cream is reformed after a few hours at room temperature.

To the touch, the cream is light, fresh (because generally aqueous) and not very sticky. It is flexible and can be applied and spread easily on the skin by applying a light constraint. After a certain time, a real film of cream forms on the skin, encompassing its irregularities.

The following additional ingredients can be added to this formula:

one or more preservatives: for example, adding 0.1% of potassium sorbate to part A and / or 0.80% of phenoxyethanol in part B;

a perfume: for example 0.10% added at the end of formulation;

one or more hydrophilic cosmetic active agents: for example added up to a few% each at the end of formulation; and / or one or more lipophilic cosmetic active agents: for example added up to a few% each in the emollient.

Claims (19)

1. O / W type emulsion, with shape memory made up, in% by weight relative to the total weight of the emulsion, of: - in the aqueous phase: o 0.2 to 1% of a copolymer of acrylate and / or methacrylate monomers having acrylate and / or methacrylate side chains esterified with a polyalkoxylated C12-C30 fatty alcohol, as a rheology modifier; o 3.00% to 15.00% of one or more humectants; ο 1% to 5% of one or more emulsifiers; - in the fatty phase: o 1.00% to 5.00% of one or more esters, natural or synthetic, of C12-C30 fatty alcohol in the form of oil, as an emollient; - Water for the aqueous phase in an amount sufficient by weight so that the total weight of the composition is 100%; - a pH adjuster in quantity by weight such that the pH of the emulsion is between 6.00 and 7.00; and - optionally one or more water-soluble or liposoluble active agents in the appropriate phase, preservatives, antioxidant, antifungal agents, colorings, perfumes, glitter or other additive. 2. Emulsion according to claim 1, characterized in that it has a viscosity of at least 100,000 Cps (10 ^-3 Pa.s). 3. Emulsion according to claim 1 or 2, characterized in that the acrylate and / or methacrylate side chains are esterified with a polyalkoxylated C12-C30 fatty alcohol having from 15 to 35 alkoxy units. 4. Emulsion according to any one of the preceding claims, characterized in that the copolymer is a copolymer of acrylates and metacrylates of fatty alcohol C12-C30 polyethoxylated and / or polypropoxylated. 5. Emulsion according to claim 4, characterized in that the copolymer is the copolymer of acrylates and methacrylates of beheneth-25. 6. Emulsion according to any one of the preceding claims, characterized in that it comprises an emulsifier of sorbitan (poly) alkoxylated and (poly) esterified type with a fatty C8-C30 carboxylic acid and / or an emulsifier of sorbitan type and / or sorbitol (poly) esterified using a C8-C30 fatty carboxylic acid. 7. Emulsion according to claim 6, characterized in that said emulsifier of sorbitan type (poly) alkoxylated and (poly) esterified by a fatty carboxylic acid C8-C30 is an emulsifier of sorbitan type monoesterified by a fatty acid C8-C30 polyethoxylated. 8. An emulsion according to claim 7, characterized in that said emulsifier is polyoxyethylene sorbitan monostearate (Polysorbate 60). 9. Emulsion according to one of claims 6 to 8, characterized in that the emulsifier type sorbitan and / or sorbitol (poly) esterified using a fatty carboxylic acid C8-C30 is an emulsifier based on monoesterified sorbityl and / or sorbitan. 10. An emulsion according to claim 9, characterized in that said emulsifier is a mixture of sorbitan stearate and sorbityl laurate. 11. An emulsion according to any one of claims 1 to 10, characterized in that the emollient is an aromatic monoester. 12. Emulsion according to claim 11, characterized in that the emollient is a benzoate monoester of a fatty alcohol C8-C20. 13. An emulsion according to claim 12, characterized in that the emollient is C12-15 alkyl benzoate. 14. Emulsion according to any one of claims 1 to 13, characterized in that the amount of oil is 3% by weight. 15. An emulsion according to claim 1 consisting of: 2.5% of Volarest ™ FL (INCI name: Acrylates / Beheneth-25 Methacrylate Copolymer), comprising approximately 0.75% of the shape memory copolymer; 2.00% Tween ™ 60 (INCI name: Polysorbate 60); 3.00% pentylene glycol; 3.00% Crodamol ™ AB (INCI name: C12-15 Alkyl Benzoate); 1.70% of Arlacel ™ LC (INCI name: Sorbitan Stearate (and) Sorbityl Laurate); a pH adjuster in an amount such that the pH of the composition is between 6.10 ± 0.5; deionized water in sufficient quantity for a total weight of composition of 100%; and optionally one or more water-soluble or liposoluble active agents in the appropriate phase, preservatives, antioxidant, antifungal agents, colorings, perfumes, glitter or other additive. 16. Method for manufacturing the shape memory emulsion according to any one of claims 1 to 15, characterized in that it comprises the steps of: forming an aqueous part A comprising: o the shape memory copolymer; o the humectant (s); and o said at least one emulsifier; if necessary, heating said part A so as to homogenize it in liquid form; form a part B comprising the emollient; add part B to part A; form an emulsion with rapid agitation; adjust the pH between 6 and 7 using a pH adjuster; optionally add one or more water-soluble or liposoluble active agents in the appropriate phase, preservatives, antioxidant, antifungal agents, colorings, perfumes, glitter or other additive. 17. The method as claimed in claim 16, characterized in that the formation of part A is divided into the subsequent formation of two parts Al and A2 which are then combined, the method comprising: forming part Al comprising the shape memory copolymer and a first emulsifier; if necessary, heating said part A1 so as to homogenize it in liquid form; 5 - form the part A2 comprising the humectant and a second emulsifier; and if necessary heating said part A2 so as to homogenize it in liquid form. 18. The method of claim 17, characterized in that said first emulsifier 10 added to part A1 is the sorbitan (poly) alkoxylated and (poly) esterified emulsifier by a C8-C30 fatty carboxylic acid. 19. The method of claim 17 or 18, characterized in that said second emulsifier added to part A2 is the sorbitan and / or sorbitol emulsifier 15 (poly) esterified using a C8-C30 fatty carboxylic acid.