阅读说明：本技术 用于头发的美容组合物 (Cosmetic composition for hair ) 是由 弗雷德里克·勃朗德尔 托马斯·布尔西耶 夏琳·博特 于 2020-03-16 设计创作，主要内容包括：本发明涉及一种用于头发护理和保养的水性美容组合物,其包含至少一种定型树脂,该树脂包含至少20mol％的甲基丙烯酸和/或其一种盐的单体单元；以及任选地至少一种丙烯酸和/或马来酸酐和/或它们的一种盐的单体单元,该树脂具有大于或等于20,000g/mol的重均分子量。本发明还涉及定型树脂用于改进这些美容组合物的耐湿性的用途。(The present invention relates to an aqueous cosmetic composition for hair care and care comprising at least one styling resin comprising at least 20 mol% of monomeric units of methacrylic acid and/or one of its salts; and optionally at least one monomer unit of acrylic acid and/or maleic anhydride and/or a salt thereof, the resin having a weight average molecular weight greater than or equal to 20,000 g/mol. The invention also relates to the use of styling resins to improve the moisture resistance of these cosmetic compositions.)

1. Aqueous cosmetic composition for hair care comprising at least one styling resin, said resin comprising:

-at least 30 mol% of monomeric units of methacrylic acid and/or one of its salts;

-at least 10 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or salts thereof;

the resin is water-soluble and has a weight average molecular weight of 20,000g/mol or more.

2. The composition of claim 1, wherein the resin comprises less than 80 mol% of monomeric units of methacrylic acid and/or a salt thereof.

3. Composition according to any one of claims 1 to 2, characterized in that the resin comprises at least 20 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or salts thereof.

4. Composition according to any one of claims 1 to 3, characterized in that the resin comprises less than 70 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or salts thereof.

5. Composition according to any one of claims 1 to 4, characterized in that the resin is a copolymer of methacrylic acid and acrylic acid and/or salts thereof.

6. Composition according to any one of claims 1 to 5, characterized in that the weight-average molecular weight of the resin is greater than or equal to 60,000 g/mol.

7. Composition according to any one of claims 1 to 6, characterized in that the weight-average molecular weight of the resin is greater than or equal to 2,000,000 g/mol.

8. The composition of any one of claims 1 to 7, wherein the resin comprises 0.05 to 10 weight percent of the composition.

9. The composition according to any one of claims 1 to 8, characterized in that it comprises:

-water;

-0.05-10 wt% of a styling resin;

-a thickening agent.

10. Composition according to any one of claims 1 to 9, characterized in that it comprises a thickener consisting of crosslinked polyacrylic acid.

11. Composition according to any one of claims 1 to 10, characterized in that it is in the form of a gel.

12. The composition according to any one of claims 1 to 11, characterized in that it has a light transmission value greater than 85%, the light transmission measurement being carried out at a light path of 420nm, 10mm, 25 ℃ for a solution comprising 2.4g/L of resin in water.

13. Use of a resin as a styling agent in an aqueous cosmetic composition for hair care to improve the moisture resistance of the cosmetic composition, the resin comprising:

-at least 30 mol% of monomeric units of methacrylic acid and/or one of its salts;

-at least 10 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or salts thereof;

the resin is water-soluble and has a weight average molecular weight of 20,000g/mol or more.

14. A styling resin for an aqueous hair care cosmetic composition, the resin comprising:

-at least 30 mol% of monomeric units of methacrylic acid and/or one of its salts;

-at least 10 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or salts thereof;

the resin is water-soluble and has a weight average molecular weight of 20,000g/mol or more.

Technical Field

The present invention relates to the field of hair care and styling technology using cosmetic compositions.

The subject of the present invention is an aqueous cosmetic composition comprising a styling resin of specific chemical nature and the use of this resin for improving the moisture resistance of said composition.

Background

Styling agents used in hair sprays are generally film-forming polymers that can hold the head together and thereby make it easier to style. Commonly used styling agents are natural gums such as guar gum or anionic polymers or neutral polymers.

In order to be effective, they must meet a certain number of criteria, primarily directed at consumer perception. For example, the film must be transparent, more or less flexible according to the desired effect, but must have a certain strength and a certain robustness. Also, when weather conditions become wet, the film must not flake off over time or under pressure (combing, rubbing) and must not become tacky.

Moreover, these polymers, also known as resins, must be able to formulate transparent compositions with rheological characteristics that meet the requirements of packaging (nebulisers, tubes, cans) and consumer expectations (gel-like viscosity, pseudoplastic, non-tacky, quick-drying).

Furthermore, cosmetic compositions based on these polymers generally comprise thickeners which provide the rheological characteristics described above.

Document WO99/13836 describes solvent-based hair cosmetic compositions containing reduced levels of Volatile Organic Compounds (VOCs) to meet environmental requirements. These compositions are based on specific solvent combinations comprising ethanol in combination with methyl acetate or butyl acetate. They also comprise a setting resin which, according to the disclosed embodiments, can be chosen from a series of polymers, in particular chosen from octylacrylamide/acrylate/butylaminoethyl methacrylate copolymers, vinyl acetate/crotonate/vinyl neodecanoate copolymers, diethylene glycol/cyclohexanedimethanol/isophthalate/sodium sulfoisophthalate copolymers. However, this document does not indicate the molar percentage of monomer or the molecular weight of the polymer. Some of the alcohol may also be replaced by water, but in this case the stability of the composition to freeze/thaw cycles is reduced.

Document EP0761199 describes cosmetic compositions for the hair comprising a styling agent and a specific acrylic copolymer. The fixing agent is chosen from anionic, cationic or amphoteric polymers, copolymers of acrylic or methacrylic acid being mentioned in the list of anionic polymers, but their chemical composition or molecular weight is not specified. The acrylic copolymer is a tetrapolymer consisting of alkyl acrylate, alkyl methacrylate, acrylic acid, and methacrylic acid. The total amount of the two acrylic and methacrylic monomers does not exceed 15% by weight. The molecular weight of such tetrapolymers is between 10,000 and 50,000 g/mol. These compositions have acceptable moisture resistance, however, this can be improved.

The scientific publication "High Molecular Weight Poly (methacrylic acid) with Narrow polyester Polymerization by RAFT Polymerization" -Macromolecules, 2009, 42, pp 1494-1499 describes the preparation of a methacrylic acid homopolymer, i.e.containing 100 mol% methacrylic acid monomer units.

Document EP0589241 describes a polymer for use in the field of printed circuits comprising at least 20 mol% of methacrylic monomer units, methyl methacrylate monomers and ethyl acrylate monomers. The polymer was used as a methyl ethyl ketone solution. The polymer is insoluble in water and therefore not suitable for use in aqueous compositions.

Document EP2248510 describes thickening polymers and their use in aqueous compositions. The aqueous composition comprises two thickening polymers, including a first thickening polymer comprising 10 to 50 wt% methacrylic acid and a second thickening polymer not comprising methacrylic acid.

Document EP1402877 describes an aqueous composition comprising a surfactant, a clay and a copolymer comprising acrylic acid, an alkyl methacrylate, a modified methacrylate and optionally methacrylic acid monomers.

Document US4196190 describes a styling resin for hair. The resin comprises a copolymer of monomers of methacrylic acid, methyl methacrylate, hydroxyethyl methacrylate and alkyl acrylate. The percentage of methacrylic acid monomer in the copolymer is preferably low, i.e., less than or equal to 18 weight percent or 21.5 mole percent, so as not to reduce curl retention.

Document US4543249 describes a copolymer and its use in compositions for the hair. The copolymer comprises from 70% to 90% by weight of methyl methacrylate and from 10% to 30% by weight of methacrylic acid and/or a salt thereof.

However, there is a need to develop new polymers with the aim of improving the moisture resistance of the styling resin of aqueous cosmetic compositions for hair care, while enabling the formulation of transparent compositions advantageously, having excellent rheological properties, and not exhibiting the above-mentioned drawbacks.

Disclosure of Invention

The applicant has surprisingly and unexpectedly found that the specific choice of polymer, as well as the judicious choice of molecular weight, according to the nature and the number of monomers constituting the polymer, makes it possible to achieve the above mentioned aims.

Accordingly, the present invention provides an aqueous cosmetic composition for hair care, which provides excellent maintenance without becoming sticky for several hours in a humid environment and is easily removed during washing.

More specifically, the present invention relates to an aqueous cosmetic composition for hair care comprising at least one styling resin, said resin comprising:

-at least 30 mol% of monomeric units of methacrylic acid and/or one of its salts;

-at least 10 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or salts thereof;

the resin is water soluble and has a weight average molecular weight greater than or equal to 20,000g/mol (greater than or equal to 20,000 g/mol).

The sum of the molar percentages of the monomer units of the resin is equal to 100%, including in particular the methacrylic acid monomer units and the acrylic acid monomer units and/or the maleic acid and/or itaconic acid monomer units. In the case of the use of at least 30 mol% of methacrylic acid and/or one of its salts and at least 10 mol% of acrylic acid and/or maleic acid and/or itaconic acid and/or one of their salts, the person skilled in the art will know how to adjust the respective percentages to 100%.

According to one embodiment of the invention, the resin consists of, or consists essentially of:

-at least 30 mol% of monomeric units of methacrylic acid and/or one of its salts;

-at least 10 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or one of their salts;

-the resin is water soluble and has a weight average molecular weight greater than or equal to 20,000g/mol (≥ 20,000 g/mol).

The term "consisting of … …" means that the resin comprises only at least 30 mol% of monomeric units of methacrylic acid and/or salts thereof and at least 10 mol% of monomeric units of acrylic acid and/or acidic maleic acid and/or itaconic acid and/or one of their salts. The sum of these mole percentages equals 100%.

The invention also relates to the use of the resin as a styling agent in aqueous cosmetic compositions for hair care, in particular for improving the moisture resistance of the cosmetic compositions.

Setting resin

In the context of the present invention, the term setting resin is understood to mean a polymer capable of imparting a temporary hold to a cosmetic composition, setting the hairstyle but also retaining the curl, even in a humid environment. In the following, the setting resin will be used to denote a "dry" polymer rather than a solution containing the polymer. In most cases, solutions containing polymers are used; the solution generally contains from 15 to 25% by weight of polymer, relative to the weight of the solution. This is referred to as a solution containing 15 to 25% by weight of active substance relative to the weight of the solution. Thus, unless contraindicated, the amount of styling resin will be given in weight percent of active.

According to a preferred embodiment of the invention, the styling resin comprises at least 30 mol% of monomeric units of methacrylic acid and/or one of its salts, preferably at least 40 mol%, more preferably at least 50 mol%, even more preferably at least 60 mol%, even more preferably at least 70 mol%.

According to a preferred embodiment of the invention, the styling resin comprises less than 99 mol% of monomeric units of methacrylic acid and/or one of its salts, preferably less than 95 mol%, more preferably less than 90 mol%, even more preferably less than 80 mol%.

Salts of methacrylic acid include in particular salts of alkaline earth metals, preferably calcium or magnesium, or of alkali metals, preferably sodium or lithium, or of ammonium, in particular quaternary ammonium.

According to a preferred embodiment of the invention, the styling resin comprises at least 1 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or one of their salts, preferably at least 10 mol%, more preferably at least 20 mol%.

According to a preferred embodiment of the invention, the styling resin comprises less than 80 mol% of monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or one of their salts, preferably less than 70 mol%, more preferably less than 60 mol%, even more preferably less than 50 mol%, still more preferably less than 40 mol% and even more preferably less than 30 mol%.

The term "mole percent" is understood to mean the mole percent relative to all moles of monomer of the resin or polymer. On the other hand, when the resin (or polymer) is crosslinked or branched, the amount of the branching agent or crosslinking agent is not considered when determining all the moles of monomers of the resin (or polymer).

According to a preferred embodiment of the present invention, the styling resin comprises monomeric units of methacrylic acid and/or one of its salts, monomeric units of acrylic acid and/or maleic acid and/or itaconic acid and/or one of its salts, and optionally a nonionic monomer and/or a cationic monomer.

Even more preferably, the styling resin comprises monomeric units of methacrylic acid and/or one of its salts, monomeric units of acrylic acid and/or one of its salts, and optionally a nonionic monomer and/or a cationic monomer.

The styling resin is preferably a copolymer of methacrylic acid with acrylic acid and/or its salts. In other words, the resin is a copolymer comprising only monomer units of methacrylic acid and acrylic acid and/or a salt thereof.

The following monomers: methacrylic acid, acrylic acid, maleic acid and itaconic acid may be in the acid form (-C (═ O) -OH) or in the form of salts of alkaline earth metals (preferably calcium or magnesium), alkali metals (preferably sodium or lithium) or ammonium (especially quaternary ammonium) (-C (═ O) -O —; cations). The preferred salt is the sodium salt.

The weight average molecular weight of the resin is preferably greater than or equal to 60,000g/mol, more preferably greater than or equal to 100,000 g/mol. Preferably less than or equal to 2,000,000g/mol (≦ 2,000,000g/mol), more preferably less than or equal to 1,000,000g/mol, even more preferably less than or equal to 500,000g/mol, even more preferably less than or equal to 300,000 g/mol.

The average molecular weight is determined in a conventional manner by size exclusion chromatography. For example, it was measured on an Agilent 1260Infinity system equipped with a Dawn HELOS, an Optilab T-Rex multi-angle light scattering detector and 3 tandem chromatography columns (Shodex SB 807-G, Shodex SB 807-HQ and Shodex 805-HQ).

The setting resin is preferably a water-soluble polymer. The term "water-soluble polymer" is understood to mean a polymer which, when exposed to 25 ℃ at 20 g.L^-1The concentration of (b) in water produces an aqueous solution of the polymer when dissolved with stirring.

The styling resin may also comprise at least nonionic and/or cationic monomer units. In this case, the amount of these monomers is preferably limited to less than 20 mol%, preferably less than 10 mol%.

The nonionic monomer is preferably selected from the group consisting of acrylamide, methacrylamide, N-vinylformamide and N-vinylpyrrolidone. Acrylamide is preferred.

Advantageously, the styling resin is free of hydroxylated monomers, for example of the hydroxypropyl acrylate and/or alkyl (meth) acrylate type.

The cationic monomer is preferably selected from quaternized or salted dimethylaminoethyl acrylate (ADAME); quaternized or salified dimethylaminoethyl methacrylate (MADAME); dimethyldiallylammonium chloride (DADMAC); acrylamidopropyltrimethylammonium Chloride (APTAC); and methacrylamidopropyltrimethylammonium chloride (MAPTAC).

One skilled in the art would know how to prepare quaternized or salted ADAME and MADAME monomers, for example, by means of acids (in particular hydrochloric acid) or alkyl halides of RX type, R being an alkyl group and X being a halogen (in particular methyl chloride).

Branching agents or crosslinking agents may also be used. Such agents are selected, for example, from methylene-bis-acrylamide (MBA), ethylene glycol diacrylate, tetraallylammonium polyethylene glycol chloride, bisacrylamide, cyanomethyl acrylate, epoxides, and mixtures thereof.

Free radical chain transfer agents, also known as chain limiting agents, may also be used. The use of chain transfer agents is particularly advantageous for controlling the molecular weight of the resulting polymer. Examples of transfer agents include methanol, isopropanol, sodium hypophosphite, 2-mercaptoethanol, sodium methallylsulfonate and mixtures thereof.

The skilled person will know how to adjust the amount of branching agent and optional transfer agent to preferably obtain a water soluble resin.

Generally, the resin or polymer does not require the development of a specific polymerization process. In fact, it can be obtained according to all the polymerization techniques well known to the person skilled in the art. In particular, it may be a solution polymerization; gel polymerization; precipitation polymerization; emulsion polymerization (aqueous or reverse); suspension polymerization; performing reactive extrusion polymerization; water-in-water polymerization; or micellar polymerization.

In the context of the present invention, the preferred polymerization technique is solution polymerization. This does make it possible to obtain polymers having molecular weights which correspond to the desired effects and benefits.

The polymerization is generally a free radical polymerization. In particular, free-radical polymerization is understood to be free-radical polymerization by means of UV, azo, redox or thermal initiators and also Controlled Radical Polymerization (CRP) techniques or matrix polymerization techniques.

Aqueous cosmetic composition for hair care and styling

In the context of the present invention, an aqueous composition means a composition containing water in such a proportion that the main phase is aqueous.

The presence of the styling resin does not alter the transparency of the aqueous cosmetic composition according to the invention. In fact, the aqueous composition consisting of water and the setting resin is preferably transparent.

The term "transparent composition" is understood to mean a composition having a light transmission value measured at 420nm of greater than 85%. The light transmittance measurement is carried out at 420nm, for example, in a cuvette (preferably a 1.5mL polystyrene cuvette) having a 10mm light path, at 25 ℃ for a solution containing 2.4g/L of the resin in water. The measurement is carried out by means of a spectrophotometer, for example of the Hach Lange DR 600 type.

The composition according to the invention may be in the form of a gel, solution, spray or spray, which is not a limiting factor. In a preferred embodiment, the composition is in the form of a gel. It is advantageously transparent according to the above definition.

The aqueous cosmetic composition according to the invention preferably comprises from 0.05 to 10% by weight, preferably from 0.1 to 5% by weight, even more preferably from 0.15 to 1% by weight, of a styling resin.

In a preferred embodiment, the composition comprises:

-water;

-0.05 to 10% by weight of a styling resin according to the invention;

-a thickening agent.

As already indicated, the aqueous cosmetic composition is advantageously transparent.

The composition according to the invention comprises water. It may also contain a mixture of water and a cosmetically acceptable solvent such as monohydric alcohols, polyhydric alcohols, glycol ethers. More particularly, lower alcohols such as ethanol, isopropanol, polyols such as diethylene glycol, glycol ethers may be mentioned.

The water concentration is generally between 50 and 99% by weight relative to the total weight of the composition. It is preferably at least 60% by weight, preferably at least 80%, even more preferably at least 90%.

Any type of thickener may be used according to the present invention, including anionic, cationic and amphoteric polymers, preferably crosslinked acrylic polyacids. Carbomers are particularly preferred. Their amount is generally between 0.01 and 10% by weight, preferably between 0.05 and 5% by weight.

The pH of the composition according to the invention is generally between 2 and 9, in particular between 3 and 8. It can be adjusted to a selected value for such applications by using alkalizing or acidifying agents commonly used in cosmetics.

When the composition according to the invention is pressurized in aerosol form to obtain a hairspray, it comprises at least one propellant which may be chosen from volatile hydrocarbons, such as n-butane, propane, isobutane, pentane, chlorinated and/or fluorinated hydrocarbons and mixtures thereof. Carbon dioxide, nitrous oxide, dimethyl ether, nitrogen, compressed air and mixtures thereof may also be used as propellants.

The propellant concentration is generally between 10 and 50% by weight relative to the total weight of the pressurized composition.

The compositions according to the invention, whether pressurized or not, may also contain surfactants, preservatives, chelating agents, emollients, colorants, viscosity modifiers, foam modulators, antifoaming agents, pearlizing agents, moisturizers, antidandruff agents, antiseborrheic agents, sunscreens, proteins, vitamins, plasticizers, hydroxy acids and perfumes.

The compositions of the present invention may also comprise other conditioning agents. These may be selected from natural or synthetic oils and waxes, fatty alcohols, esters of polyols, glycerol esters, silicone gums and resins or mixtures of these various compounds.

Of course, the person skilled in the art will take care to select the optional compounds to be added to the composition according to the invention such that the advantageous properties inherent to the composition according to the invention are not or substantially not altered by the intended addition.

For example, hair care compositions for use according to the present invention are gels or solutions designed to be rinsed off or left on. For example, they are wave emulsions, blow-dry emulsions, styling compositions (hair sprays) and styling compositions. The emulsion may be packaged in various forms, such as a spray bottle, pump bottle or aerosol container to ensure application of the composition in the form of a spray. For example, the composition in gel form is packaged in a can, which is preferably transparent.

The present invention will be described in more detail with reference to the following examples. They are merely illustrative of the invention and are not limiting.

Drawings

Figure 1 shows the percent curl retention of a composition containing a styling resin as a function of time.

Detailed Description

1/Synthesis of the styling resin

203.0 grams of water and 50 milligrams of sodium hypophosphite were charged to a jacketed reactor equipped with a mechanical stirrer with half-moon paddle, refrigerant and temperature probe. The medium was heated to 83 ℃. When the temperature was reached, a solution containing Acrylic Acid (AA) and methacrylic acid (AMA) or hydroxypropyl acrylate (HPA) comonomers was added over 120 minutes. The amounts of AA and AMA or HPA are shown in Table 1.

At the same time, a 10.0% by weight sodium persulfate solution was added over 135 minutes. When the sodium persulfate solution was complete, the medium was cooled to 60 deg.C and 156.8 grams of water was added to the medium. The pH is adjusted to between 2.2 and 3.0 and the medium is then stirred for a further hour. The product was then filtered at 300 μm.

Polymer solutions corresponding to examples 2 to 6 were obtained, the compositions and average molecular weights by weight (Mw) of which are detailed in table 1. The resin of the composition of example 1, as such, contained only acrylic monomers.

TABLE 1 composition and molecular weight of the styling resins

Preparation of clear aqueous cosmetic composition for hair care

Resins corresponding to examples 1 to 6 were incorporated into the gel formulations described in table 2. We thus obtained compositions C '1 to C'6 comprising respectively the styling resins 1 to 6.

TABLE 2 Hair spray composition

The Qs 100-quantity is sufficient to reach 100%

EDTA-EDTA

TEA ═ triethanolamine

Qs pH 6.5 is sufficient to reach a pH of 6.5

The transparency of the gel was determined by measuring the light transmittance on a Hach Lange DR 600 spectrophotometer. These measurements were made at 420nm in a 1.5mL PS cuvette for a solution containing 2.4g/L resin in water.

The viscosity of the gel was measured at 23 ℃ using a Brookfield RVT viscometer at 20 rpm. The person skilled in the art knows how to select the module 7 as a function of the viscosity of the gel. In this case, the module 7 is used in consideration of the composition of the gel and the desired texture.

The results are shown in Table 3.

TABLE 3 viscosity and clarity of styling gels

The gels of the compositions C '1 to C'6 obtained were all transparent, since their transparency was greater than 85% T. Their viscosity and their rheological properties are very good.

3/moisture resistance of the setting resin

The moisture resistance of the resin was evaluated by the "curl Retention" test.

The protocol is as follows: 3.1 g of the resin was added to 87.5 g of a hydroalcoholic water/ethanol solution (37/63). We thus obtained compositions C '1 to C'6 comprising the resins of examples 1 to 6, respectively.

A lock of European hair was immersed in a hydroalcoholic resin solution and excess solution was removed by passing a lock of hair across its entire length between two fingers. The tress of hair is then combed once and rolled onto a curling iron.

The tresses were then placed on a curler for 24 hours at 23 ℃ and 50% relative humidity. The tresses were spread and placed in an oven controlled at 25 ℃ with 90% humidity. t is t₀The length of the hair strand at (a) is used as a reference (Li) for calculating the% curl retention (% TB), also known as the% curl retention (% CR). The length of the hair strands is measured at different time intervals (Lt).

Percent curl retention was calculated using the following ratio:

％TB＝[(L–Lt)/(L–Li)]*100

the length of the spread hair bundle is 19cm.

We observed in fig. 1 that compositions C '3 and C'4 comprising the resins of examples 3 (45% mol AMA) and 4 (71% mol AMA), respectively, provided excellent moisture resistance, but greater than those obtained with resin compositions C '1 and C'2 comprising example 1(0 mol% AMA) and example 2(8.5 mol% AMA). The curl retention of composition C '2 was inferior to that of composition C' 1. This indicates that the addition of AMA to the resin is not the only parameter to increase crimp strength, but that at least 30 minimum mole percent of AMA in the AA/AMA copolymer is necessary to obtain better crimp retention.

We also observed from the results of compositions C '3 and C'4 in fig. 1 that an increase in the amount of AMA in the copolymer makes it possible to obtain increased moisture resistance.

Furthermore, compositions C '5 and C'6 have very poor moisture resistance. The observation of the comparison of curve C '6 with curve C'3 lets us say that the substitution of HPA for AMA greatly reduces the moisture resistance.

An observation comparing curve C '5 with curve C'3 may demonstrate the importance of the molecular weight of the resin to the moisture resistance of the composition in which it is included. In fact, composition C'5, which comprises an AA/AMA 45/55 copolymer having a weight-average molecular weight of less than 20,000g/mol, does not improve curl retention.

Finally, the hair tresses prepared with compositions C '3 and C'4 according to the invention do not exhibit any stickiness and are easily removed during the washing process, thus meeting the required criteria.

4/examples 7 and 8

A methacrylic homopolymer (example 7), i.e.containing 100 mol% methacrylic monomer units, was prepared according to the method described in the scientific publication "High Molecular Weight Poly (methacrylic acid) with Narrow polyester Polymerization by RAFT Polymerization" -Macromolecules, 2009, 42, page 1494-1499. The polymer obtained corresponds to example 7.

Another polymer was prepared according to the same method except that 12 mol% of methacrylic acid was replaced with 12 mol% of acrylic acid. The polymer obtained corresponds to example 8.

The polymer of example 7 has such a high viscosity that it cannot be used by the formulator of a cosmetic composition because it is too difficult to handle. Dilution tests with reduced viscosity also do not give a product that is satisfactory to the user due to stability problems. And therefore its characteristics were not evaluated.

The polymer of example 8 is processable. Hair spray composition C'8 was prepared according to the formulation of table 2 using the polymer of example 8. The gel viscosity was 52,000CPS and the transparency was 91%. The moisture resistance test, which was the same as part 3/was carried out, and the curl retention at 300 minutes was 93%, which was very satisfactory, demonstrating the technical effect of the polymer of the present invention.

5/examples 9 to 14

Polymers of lines 2, 5 and 8 in table 1 of document EP1402877 are produced. They are labeled examples 9, 11 and 13, respectively. Polymer 10 was made into polymer 9 in which 10 mol% of ethyl acrylate was replaced with 10 mol% of acrylic acid. Polymer 12 was made into Polymer 11 in which 25 mol% of the ethyl acrylate was replaced with 25 mol% of methacrylic acid. Polymer 14, for example polymer 13, was prepared in which 25 mol% of the methyl acrylate was replaced by 25 mol% of methacrylic acid.

Table 4 summarizes the compositions of polymers 9 to 14.

TABLE 4 compositions of polymers 9 to 14

The values for Acrylic Acid (AA), methacrylic acid (AMA), Ethyl Acrylate (EA), Methyl Acrylate (MA) and Lipol 1 are expressed in mol%. The values of diallyl phthalate (DAP) and n-dodecyl mercaptan (DDM) are expressed in mass%. The molecular weight of Lipol 1 is 1188 g/mol.

Lipol 1 is a lipophilic modifying monomer having a linear saturated alkyl group of 18 carbon atoms linked to a methacryloyl group by 20 ethylene oxide residues.

Polymers 9 to 14 were used in the hair gel compositions of table 2, and the resulting gel compositions were designated C '9 to C'14, respectively. The viscosity of the gels and their transparency were measured according to the same method as previously described. The results are shown in Table 5.

Table 5-viscosity and clarity of styling gels C '9 to C' 14.

The results of the moisture resistance test of the same section 3/and the curl retention at 300 minutes are shown in Table 6.

TABLE 6 curl Retention for compositions C '9 to C'14

Increasing the proportion of acrylic acid from 7.13 mol% to 15 mol% in example 9 resulted in an increase in curl retention of more than 10%. Increasing the proportion of acrylic acid from 11.58 mol% to 36.58 mol% in example 11 resulted in an increase in curl retention of more than 30%. Increasing the proportion of acrylic acid from 10.55 mol% to 30.55 mol% in example 13 resulted in an increase in curl retention of over 31%.

These results may prove that the polymers according to the invention have better properties, in particular compared with the polymers of the prior art.