The present invention relates to a new polymer, a process for making it and its use as thickening agent (also called thickener). The polymer comprises repeating units derived from acrylic acid and/or methacrylic acid, repeating units derived from a monomer which is, in a wider sense, an ethoxylated or propoxylated fatty alcohol substituted with a hydrophobic moiety, repeating units derived from vinyl pyrrolidone and repeating units derived from 1 -vinyl imidazole.

Thickening agents are substances which are used to increase the viscosity, respectively the overall rheological profile of aqueous formulations, e. g. shower gels, shampoos, hair relaxers, emulsions (o/w, w/o, multiple emulsions) for several application purposes (face/body/baby/depilatories) and various other cosmetic formulations. There are polymeric and non-polymeric thickening agents.

The demand for polymers as formulation aids (adjuvants) for cosmetic applications is still increasing. Ideally, new structures shall combine the known advantages of existing polymers but provide extra benefits as well. A frequently expected property of polymeric adjuvants is compatibility of the polymer with electrolytes without reducing overall cosmetic acceptance by negative sensorial or rheological characteristics. Electrolytes are present in many cosmetic formulations, e. g. as ionic emulsifiers, surfactants or active ingredients or as traces/impurities carried in different ingredients or as preservatives (e. g. sodium benzoate etc.).

There are different methods for making polymeric adjuvants for cosmetic applications in general and polymeric thickening agents in particular.

One method is precipitation polymerization. Monomers are dissolved in a volatile, low boiling solvent such as heptane, petrol, methylene chloride. Then, polymerization is carried out and the polymer produced is obtained as a precipitate. Examples of polymers produced in this way are polyacrylic acid based thickeners, also called carbomers. Examples of commercially available carbomers are Carbopol ^® 980, Carbopol ^® Ultrez 10 and 30, Rheocare ^® C Plus, TegoCarbomer ^® 931. Furthermore hydrophobically modified polymers can be produced by precipitation polymerization. Examples are acrylates/C 10-30 alkyl acrylate crosspolymers, commercially available as Pemulen ^® TR-types, Carbopol ^® Ultrez 20 and 21 . The solvents used in the precipitation polymerization method are difficult to handle and need to be recycled, which is a costly process. Additionally the polymers need to be isolated from the l solvents and dried. The polymers produced are usually obtained in the form of a powder. Polymer powders have handling disadvantages, e. g. dust issues, dilution time etc.

Another method is emulsion polymerization. In this method monomers are emulsified in water. After polymerization a dispersion of a polymer in water is obtained. Typically these dispersions have a content of about 30 % by weight of dispersed polymer. Polymers of the ASE type (alkali swellable emulsion) and of the HASE type (hydrophobically modified alkali swellable emulsion) are made by emulsion polymerization.

Another method is the reverse emulsion polymerization, resulting in so called liquid dispersion polymers (LDP), also called inverse emulsion polymers (IEP). In this process monomers are dissolved in water which is the discontinuous phase of a water in oil emulsion. The polymerization is carried out in the individual aqueous solution droplets, resulting in polymer dispersions in oil. The water used in this process can either be removed by distillation or it can remain in the dispersion.

The preparation of precipitation polymers starting with a solution of monomers in an oil as solvent has also been described. WO 99/29735 discloses a non-aqueous, heterogeneous polymerization process with vinyl monomers in an oil as solvent. N-vinylpyrrolidone is used as vinyl monomer. It is disclosed that the dispersions of polymers in oils that are obtained may be used in cosmetic compositions.

The methods explained in the previous paragraphs have disadvantages. Emulsion polymers can only be made using water insoluble monomers that are not too hydrophobic. Additionally emulsion polymers including acidic monomers like acrylic acid need to be neutralized to a pH value of 6 or higher after polymerization, often even 6.5 or higher, which is not a desired pH level for many modern cosmetic applications. The reason for this is that the monomer in its deprotonated form is highly soluble in water and therefore not suitable for emulsion polymerization and that, on the other hand, only the partially neutralized polymer has a significant thickening effect due to the repulsion of the negatively charged groups in the polymeric molecule.

The thickening agents known in the art have disadvantages. Their thickening mechanism combines repulsive effects with associative effects but is available only in media which have a relatively high pH value as explained in the previous paragraph. LDPs can only be made from water soluble monomers. This clearly limits flexibility with respect to the monomers that can be used to make LDPs. The thickening mechanism of LDPs is predominantly driven by repulsion effects. Only small amounts of so called associative monomers can be incorporated. Examples of associative monomers are lauryl acrylate, stearyl methacrylate and their ethoxylated derivatives. In general, associative monomers are monomers that provide physical crosslinking of the copolymers made including the associative monomer. E. g. a copolymer including repeating units derived from lauryl acrylate will, when dissolved in water, form a network which is physically crosslinked by the attraction of the hydrophobical lauryl moieties.

WO 2008/087326 discloses an anionic copolymer containing at least one surface-active monomer and its use as a thickening agent. The copolymer disclosed has a thickening effect in solutions with a high content of electrolytes, i. e. it has a high electrolyte tolerance.

The problem underlying the present invention is to provide a polymer that can be used as thickening agent in cosmetic formulations. Preferably, this polymer shall have a high electrolyte tolerance. Preferably, it shall be possible to make this polymer using an efficient, simple and cost-effective process.

This problem is solved by a polymer comprising

A) 5 - 40, preferably 10 - 35, more preferably 15 - 30, more preferably 20 to 25, % by weight repeating units derived from acrylic acid,

B) 1 - 30, preferably 1 to 25, more preferably 1 to 20, more preferably 5 - 20, more preferably 8 - 15 % by weight repeating units derived from methacrylic acid, with the proviso that the sum of the amounts of repeating units derived from acrylic acid and repeating units derived from methacrylic acid is at least 7 % by weight,

C) 1 - 30, preferably 1 - 25, more preferably 1 - 20, more preferably 5 - 20, more preferably 8 - 15, % by weight repeating units derived from a monomer according to formula (I)

in which

R is selected from the group consisting of the moiety according to formula (II), the moiety according to formula (III), the maleic moiety, the itaconic moiety, the crotonic moiety and the vinylphthalic moiety, wherein in each case the oxygen radical of the moiety makes the chemical bond to the rest of the molecule according to formula (I), preferably R is the moiety according to formula (II) or the moiety according to formula (Hi),

R1 is hydrogen or methyl, preferably hydrogen, m is 0 to 50, preferably 1 to 50, more preferably 10 to 40, and most preferably 20 to 30,

R' is a hydrophobic moiety selected from linear or branched alkyl, alkylaryl or arylalkyl radicals, preferably having at least 6 C-atoms, R ^' preferably is selected from linear alkyl radicals having 8 to 20 carbon atoms, still more preferred from linear alkyl radicals having 12 to 18 carbon atoms, and most preferably from linear alkyl radicals having 16 to 18 carbon atoms,

D) 40 - 70, preferably 55 to 65, % by weight repeating units derived from vinyl pyrrolidone,

E) 0.1 - 10, preferably 1 to 8, % by weight repeating units derived from 1 -vinyl imidazole,

F) 0 - 5, preferably 0.1 to 5, % by weight repeating units derived from a crosslinker having at least two vinyl groups, and

G) 0 - 10, preferably 0 to 5, more preferably 0 to 2, % by weight repeating units derived from a further monomer having at least one vinyl group.

This polymer is a first subject of the present invention. The monomers used to make the polymer according to the present invention are commercially available or can be made using standard methods of organic chemistry. The monomer according to formula (I) can be made from the unsaturated acid underlying this monomer plus ethylene oxide or propylene oxide plus the alcohol underlying this monomer. The acid is either reacted with ethylene oxide or propylene oxide and the resulting intermediate is reacted with the alcohol or the alcohol is reacted with ethylene oxide or propylene oxide and the resulting intermediate is reacted with the acid. In a preferred embodiment of the polymer according to the present invention the crosslinker according to the present invention is selected from the group consisting of pentaerythrite triallylether (preferably used in an amount of 0.1-1 % by weight) and trimethylolpropane trimethacrylate (preferably used in an amount of 0.1- 5 % by weight)

Pentaerythrite triallylether has the following formula:

trimethylolpropane trimethacrylate has the following formula:

Even if the polymer according to the present invention does not contain a crosslinker it is difficult to determine the average molar mass of it. This is so because the polymer according to the present invention has the tendency to form physically crosslinked networks through the association of the repeating units derived from monomer C. The thickening property of the polymer according to the present invention shows that it really is a polymer having a significant degree of polymerization.

In its most general embodiment the polymer according to the present invention is a polymer comprising

A) 5 - 40 % by weight repeating units derived from acrylic acid,

B) 1 - 30 % by weight repeating units derived from methacrylic acid, with the proviso that the sum of the amounts of repeating units derived from acrylic acid and repeating units derived from methacrylic acid is at least 5 % by weight, 1 - 30 % by weight repeating units derived from a monomer according to formula (I)

in which

R is selected from the group consisting of the moiety according to formula (II), the moiety according to formula (III), the maleic moiety, the itaconic moiety, the crotonic moiety and the vinylphthalic moiety, wherein in each case the oxygen radical of the moiety makes the chemical bond to the rest of the molecule according to formula (I),

R1 is hydrogen or methyl, m is 0 to 50,

R' is a hydrophobic moiety selected from linear or branched alkyl, alkylaryl or arylalkyl radicals,

D) 40 - 70 % by weight repeating units derived from vinyl pyrrolidone,

E) 0.1 - 10 % by weight repeating units derived from 1 -vinyl imidazole,

F) 0 - 5 % by weight repeating units derived from a crosslinker having at least two vinyl groups, and

G) 0 - 10 % by weight repeating units derived from a further monomer having at least one vinyl group. A preferred embodiment the polymer according to the present invention is a polymer comprising

A) 10 to 35 % by weight repeating units derived from acrylic acid,

B) 1 - 25 % by weight repeating units derived from methacrylic acid,

C) 1 - 25, preferably 8 to 15, % by weight repeating units derived from a monomer according to formula (I)

in which

R is selected from the group consisting of the moiety according to formula (II) and the moiety according to formula (III)

R1 is hydrogen, m is 1 to 50, more preferably 10 to 40, and most preferably 20 to 30,

R' is a hydrophobic moiety selected from linear or branched alkyl, alkylaryl or arylalkyi radicals having at least 6 C-atoms, R ^' preferably is selected from linear alkyl radicals having 8 to 20 carbon atoms, still more preferred from linear alkyl radicals having 12 to 18 carbon atoms, and most preferably from linear alkyl radicals having 16 to 18 carbon atoms,

D) 40 - 70, preferably 55 to 65, % by weight repeating units derived from vinyl pyrrolidone,

E) 0.1 - 10, preferably 1 to 8, % by weight repeating units derived from 1 -vinyl imidazole, F) 0 - 5, preferably 0.1 to 5, % by weight repeating units derived from a crosslinker having at least two vinyl groups, and

G) 0 - 10, preferably 0 to 5, more preferably 0 to 2, % by weight repeating units derived from a further monomer having at least one vinyl group,

wherein the crosslinker F is selected from the group consisting of pentaerythrite triallylether (preferably used in an amount of 0.1 -1 % by weight) and trimethylolpropane trimethacrylate (preferably used in an amount of 0.1 - 5 % by weight).

Another preferred embodiment the polymer according to the present invention is a polymer comprising

A) 15 to 30 % by weight repeating units derived from acrylic acid,

B) 1 to 20 % by weight repeating units derived from methacrylic acid,

C) 1 to 20, % by weight repeating units derived from a monomer according to formula (I)

in which

R is selected from the group consisting of the moiety according to formula (II) and the moiety according to formula (III)

R1 is hydrogen, m is 10 to 40, preferably 20 to 30,

R' is selected from linear alkyl radicals having 8 to 20 carbon atoms, preferably from linear alkyl radicals having 12 to 18 carbon atoms, and most preferably from linear alkyl radicals having 16 to 18 carbon atoms, D) 55 to 65, % by weight repeating units derived from vinyl pyrrolidone,

E) 1 to 8, % by weight repeating units derived from 1 -vinyl imidazole,

F) 0 - 5, preferably 0.1 to 5, % by weight repeating units derived from a crosslinker having at least two vinyl groups, and

G) 0 - 10, preferably 0 to 5, more preferably 0 to 2, % by weight repeating units derived from a further monomer having at least one vinyl group,

wherein the crosslinker F is selected from the group consisting of pentaerythrite triallylether (preferably used in an amount of 0.1 -1 % by weight) and trimethylolpropane trimethacrylate (preferably used in an amount of 0.1 - 5 % by weight).

Another preferred embodiment the polymer according to the present invention is a polymer comprising

A) 10 to 20 % by weight repeating units derived from acrylic acid,

B) 8 to 15 % by weight repeating units derived from methacrylic acid,

C) 8 to 15, % by weight repeating units derived from a monomer according to formula (I)

in which

R is selected from the group consisting of the moiety according to formula (II) and the moiety according to formula (III)

R1 is hydrogen, m is 20 to 30, R' is selected from linear alkyl radicals having 12 to 18 carbon atoms, preferably from linear alkyl radicals having 16 to 18 carbon atoms,

D) 55 to 65, % by weight repeating units derived from vinyl pyrrolidone,

E) 1 to 8, % by weight repeating units derived from 1 -vinyl imidazole,

F) 0 - 5, preferably 0.1 to 5, % by weight repeating units derived from a crosslinker having at least two vinyl groups, and

G) 0 to 5, preferably 0 to 2, % by weight repeating units derived from a further monomer having at least one vinyl group,

wherein the crosslinker F is selected from the group consisting of pentaerythrite triallylether (preferably used in an amount of 0.1 -1 % by weight) and trimethylolpropane trimethacrylate (preferably used in an amount of 0.1 - 5 % by weight).

It is believed that the polymer according to the present invention, in a preferred embodiment in which this polymer comprises repeating units derived from AA (acrylic acid), MAA (methacrylic acid), VP (N-vinyl pyrrolidone), VI (1 -vinyl imidazole) and LUMA (PEG 25 stearyl methacrylate), has the following structural formula. In this formula the numbers of m, n, o, p and q have to be chosen so that the weight-% ratios of the polymer according to the present invention are fulfilled. It is believed that the sequence of the repeating units in the polymer chain is a statistical sequence.

In this structure and in the polymer according to the present invention in general the repeating units derived from VP increase the flexibility and the hydrophilicity of the polymer. The film forming capabilities of the repeating units derived from VP support positive sensorial aspects of the polymer according to the present invention. The polymer according to the present invention comprises acidic COOH groups. It also comprises basic nitrogen atoms in the repeating units derived from vinyl imidazole. Therefore, depending on the pH value of the medium surrounding the polymer according to the present invention, the structure of the polymer according to the present invention may comprise deprotonated COOH groups, i. e. anionic COO ^" groups. It may also comprise protonated, cationic vinyl imidazolinium moieties. In strongly acidic surroundings the polymer according to the present invention has more cationic than anionic groups. The counterions to balance this overall charge of the polymer according to the present invention can be various counterions depending on what counterions have been brought into contact with the polymer according to the present invention. Non-limiting examples of anionic counterions are halogen anions, especially chloride. Furthermore and due to the widespread use of organic acids in cosmetic applications counterions as citrate, lactate, glycolate, benzoate, formate, acetate etc. can be present. In strongly basic surroundings the polymer according to the present invention has more anionic than cationic groups. The counterions to balance this overall charge of the polymer according to the present invention can be various counterions depending on what counterions have been brought into contact with the polymer according to the present invention. Non-limiting examples of anionic counterions are alkali cations, especially sodium cations and potassium cations. Furthermore nitrogen based counterions as ammonium ions or aminomethyl propanol derived ions and similar ions can be present. In any case the term "the polymer according to the present invention" not only comprises the polymer according to the present invention which has no overall charge but it also comprises the polymer according to the present invention which has been neutralized either by acids or by bases so that it has an overall charge which is either negative or positive and which is balanced by suitable counterions being present in the surrounding of the polymer according to the present invention.

The polymer according to the present invention can be made by a precipitation process using an oil as solvent. Specifically, the process according to the present invention for making the polymer according to the present invention comprises the steps

• providing a solution of monomers A to G in the amounts required in a solvent, the solvent being selected from the group consisting of at least one cosmetically acceptable emollient, at least one nonionic surfactant and mixtures thereof,

• copolymerizing monomers A to G so that a dispersion of the polymer according to the present invention in the solvent is formed, and

• optionally isolating the polymer. The solvent used in the process according to the present invention may comprise further substances apart from the substances named in the previous paragraph. It may comprise low amounts of water, organic solvents or other substances. Preferrably the solvent has a purity of at least 90 % by weight, more preferably at least 95 % by weight, more preferably 98 % by weight, more preferably 99 % by weight, more preferably 99.5 % by weight.

The copolymerization may be initiated regulated and stopped by means known in the art.

This process is another subject of the present invention.

In a preferred embodiment the solvent used in the process according to the present invention has a water content of less than 5 % by weight, preferably less than 2, more preferred less than 1 , and most preferred less than 0.5 % by weight.

The cosmetically acceptable emollient according to the present invention can be any cosmetically acceptable emollient. Based on their chemical structures, such emollients can be categorized as esters, hydrocarbons, glycerides, ethers, fatty alcohols, silicone derivatives and other emollients.

Examples of emollients that can be used as emollient according to the present invention are vegetable oils, fatty acid alkyl esters based on C6-C22 fatty acids, mineral oils, silicone oils and their mixtures. The term "cosmetically acceptable" refers to those kinds of organic oils or blends of oils which can be used in such compositions which come into intense and/or direct contact to the human skin, scalp, hair or nails, without harming them.

Examples illustrating the nature of suitable emollients without limiting the invention to these examples are: C6-C22-Fatty alcohols, Guerbet alcohols based on fatty alcohols having 6 to 18, preferably 8 to 10, carbon atoms, esters of linear C6-C22-fatty acids with linear or branched C6-C22-fatty alcohols or esters of branched C6-C13-carboxylic acids with linear or branched C6-C22-fatty alcohols, such as, for example, myristyl myristate, myristyl palmitate, myristyl stearate, myristyl isostearate, myristyl oleate, myristyl behenate, myristyl erucate, cetyl myristate, cetyl palmitate, cetyl stearate, cetyl isostearate, cetyl oleate, cetyl behenate, cetyl erucate, stearyl myristate, stearyl palmitate, stearyl stearate, stearyl isostearate, stearyl oleate, stearyl behenate, stearyl erucate, isostearyl myristate, isostearyl palmitate, isostearyl stearate, isostearyl isostearate, isostearyl oleate, isostearyl behenate, isostearyl oleate, oleyl myristate, oleyl palmitate, oleyl stearate, oleyl isostearate, oleyl oleate, oleyl behenate, oleyl erucate, behenyl myristate, behenyl palmitate, behenyl stearate, behenyl isostearate, behenyl oleate, behenyl behenate, behenyl erucate, erucyl myristate, erucyl palmitate, erucyl stearate, erucyl isostearate, erucyl oleate, erucyl behenate and erucyl erucate. Also suitable are esters of linear C6-C22-fatty acids with branched alcohols, in particular 2-ethylhexanol, esters of C18-C38- alkylhydroxy carboxylic acids with linear or branched C6-C22-fatty alcohols, in particular dioctylmalate, esters of linear and/or branched fatty acids with polyhydric alcohols (such as, for example, propylene glycol, dimerdiol or trimertriol) and/or Guerbet alcohols, triglycerides based on C6-C10-fatty acids, liquid mono-/di-/triglyceride mixtures based on C6-C18-fatty acids, esters of C6-C22-fatty alcohols and/or Guerbet alcohols with aromatic carboxylic acids, in particular benzoic acid, esters of C2- C12- dicarboxylic acids with linear or branched alcohols having 1 to 22 carbon atoms or polyols having 2 to 10 carbon atoms and 2 to 6 hydroxyl groups, branched primary alcohols, substituted cyclohexanes, linear and branched C6-C22-fatty alcohol carbonates, such as, for example, Dicaprylyl Carbonate (Cetiol® CC), Guerbet carbonates, based on fatty alcohols having 6 to 18, preferably 8 to 10, carbon atoms, esters of benzoic acid with linear and/or branched C6-C22-alcohols (e.g. Finsolv® TN), linear or branched, symmetrical or asymmetrical dialkyl ethers having 6 to 22 carbon atoms per alkyl group, such as, for example, dicaprylyl ether (Cetiol® OE), ring-opening products of epoxidized fatty acid esters with polyols and/or silicone oils (cyclomethicones, silicone methicone grades, etc.). Further preferred emollients are selected from silicone oils, including hydrophobically modified silicone oils (e.g. Dow Corning® 2502 by Dow Corning).

Suitable as emollient are also vegetable oils.

Preferred cosmetic acceptable emollients are selected from

i) Fatty alcohols and Guerbet alcohols,

ii) Esters of Guerbet alcohols with linear or branched fatty acids,

iii) Fatty acid esters of linear or branched fatty alcohols,

iv) Fatty acid esters of glycerol

v) Dialkylcarbonates,

vi) Dialkylethers,

any mixtures of the compounds i) to vi).

Especially preferred emollients according to the present teaching are selected from groups iii), iv), v) and/or vi) as well as any mixture thereof.

Further preferred emollients according to the present invention are

• mono-, di- or trialk(en)yl glycerids,

• isopropyl alkyl or alkenyl esters, e. g. isopropyl myristate or isopropyl palmitate, • dialk(en)yl carbonates,

• dialk(en)yl ethers,

• alk(en)yl carboxylate esters,

• (un)saturated fatty alcohols, and

• Guerbet alcohols.

The preferred chain length of the alk(en)yl groups in each case is C ₆ to C ₂ 2-

In one embodiment of the present invention the cosmetically acceptable emollient is a triglyceride of at least one fatty acid having 6 to 22 carbon atoms.

In one embodiment of the present invention the cosmetically acceptable emollient is a diester of adipic acid of at least one fatty acid having 6 to 22 carbon atoms.

The surfactant to be used in the process according to the present invention can be any nonionic surfactant.

Typical examples of nonionic surfactants which may be used as surfactant according to the present invention are fatty alcohol polyglycol ethers, alkylphenol polyglycol ethers, fatty acid polyglycol esters, fatty acid amide polyglycol ethers, fatty amine polyglycol ethers, alkoxylated triglycerides, mixed ethers and mixed formals, optionally partially oxidized alk(en)yl oligoglycosides and glucuronic acid derivatives, fatty acid N-alkylglucamides, protein hydrolyzates (especially wheat-based vegetable products), polyol fatty acid esters, sugar esters, sorbitan esters, polysorbates, amine oxides, fatty acid mono- and diethanolamides and polyglycerol fatty acid esters. If the nonionic surfactants contain polyglycol ether chains, they may have a conventional homolog distribution, but preferably have a narrow homolog distribution.

In one embodiment the surfactant is a compound having the following formula:

in which R1 is an alkyl or alkenyl group having 6 to 22 carbon atoms, preferably having 12 to 22 carbon atoms,

R2 is either hydrogen or a methyl group,

m is 1 to 50, preferably 1 to 20, more preferably 2 to 15,

R3 is hydrogen or a (hydrophobic) linear alkyl group having 1 to 22 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms.

In a preferred embodiment R1 is a linear, primary alkyl or alkenyl group having 6 to 22 carbon atoms, preferably having 12 to 22 carbon atoms, i. e. R1 is derived from a fatty alcohol.

The total amount of monomers A to G compared to the amount of monomers A to G plus the amount of solvent is preferably 10 - 60 % by weight, more preferably 20 to 50, more preferably 30 to 50 % by weight.

Preferably the process according to the present invention is carried out in such a way that the amount of polymer obtained is at least 99 % by weight, preferably at least 99.9 % by weight of the amount of monomers A to G used.

In a preferred embodiment the polymer is not isolated but the dispersion obtained is the desired product. As this dispersion comprises at least one cosmetically acceptable emollient or at least one nonionic surfactant or mixtures thereof it may be used as raw material for cosmetic formulations that will then contain, apart from further components, the polymer according to the present invention and at least one cosmetically acceptable emollient or at least one nonionic surfactant or mixtures thereof.

Therefore, a further subject of the present invention is a dispersion comprising

• the polymer according to the present invention, preferably in amount of 10 - 60 % by weight, more preferably 20 to 50, more preferably 30 to 50 % by weight, and

• a solvent being selected from the group consisting of at least one cosmetically acceptable emollient, at least one nonionic surfactant and mixtures thereof.

A further subject of the present invention is a cosmetic composition comprising

• the polymer according to the present invention, preferably in an amount of 0.05 - 10% by weight, more preferably 0.1 - 5.0 % by weight, and • a solvent being selected from the group consisting of at least one cosmetically acceptable emollient, at least one nonionic surfactant and mixtures thereof, preferably in amount of 0.05 - 50 % by weight, more preferably 0.1 - 5 % by weight, and

• optionally further cosmetic ingredients.

In a preferred embodiment the cosmetic composition according to the present invention is a clear gel, a gel cream, a lamellar or non-lamellar care emulsion, a microemulsion, a dispersion (e. g. a make up composition or a sun protection composition), a surfactant based shampoo or body wash composition.

By varying the monomer composition used to make the polymer according to the present invention it is possible to optimize the properties of the polymer. Thickening performance, film forming properties or conditioning strength can be optimized. Therefore, the polymer according to the present invention can be applied in different fields. In case of good film forming properties the polymer may be used as hair styling polymer. The main application of the polymer according to the present invention is its use as thickener in cosmetic compositions.

The polymer according to the present invention in general has advantageous properties in the following areas:

• high thickening performance in water based formulation concepts;

• no relevant incompatibilities; the polymer shows convincing performance in anionic, non-ionic and cationic environments;

• outstanding compatibility with electrolytes allowing the use in surfactant based wash applications as well as in gels and creams with high salt/active loads;

• formation of crystal clear gels is possible;

• can be used in a wide range of pH values, e. g. pH 4 to 12;

• has excellent electrolyte compatibility.

The polymer according to the present invention can be made with the efficient process according to the present invention. Examples

In the examples % means % by weight.

EO means ethylene oxide.

PEG means polyethylene glycol. PEG-140 means polyethylene glycol having an average degree of polymerization of 140 ethylene glycol units (number average).

Preparation of Polymer Dispersions

Polymers were prepared having the composition given in the following table.

^* stearyl alcohol ethoxylated with 25 units ethylene oxide (on average) and subsequently esterified with methacrylic acid.

The polymers were prepared in the following way. The monomers were dissolved in the emollient or surfactant listed in the following table. The relative amount of each monomer was chosen according to the previous table. Polymerization was initiated and resulted in dispersions A to F according to the following table.

The following describes the process used to make the dispersions in more detail. Dispersions A, B and C:

The initiator 2,2'-azobis(2.4-dimethyl valeronitrile) was dissolved in a small portion of the matrix (emollient or surfactant) (1 to 10% of the matrix) and thus resulted in solution 1 . The monomers were diluted in a portion of 20 to 40% of the matrix and thus resulted in solution 2. The remaining emollient (or surfactant) was charged into the reaction vessel and heated to 60°C. To initiate polymerization the monomer solution (solution 2) was added at 60°C within 3 hours. Simultaneously the initiator solution (solution 1 ) was added within 5 hours. A temperature of about 60°C was kept during this time. Subsequently the reaction mixture was kept for 5 hours at 80°C.

Dispersions D, E and F:

The initiator 2,2'-azobis(2.4-dimethyl valeronitrile) was dissolved in a small portion of the matrix (1 to 10% of the matrix) and thus resulted in solution 1 . The monomers were mixed to a homogeneous solution (solution 2). The remaining emollient (or surfactant) was charged into the reaction vessel and heated to 60°C. To initiate polymerization the monomers (solution 2) were slowly added at 60°C (within 3 to 6 hours). Simultaneously the initiator solution (solution 1 ) was added within 5 to 6 hours. Subsequently the reaction mixture was kept for 5 hours at 80°C.

^* glycerol esterified with three units of a mixture of capric acid (decanoic acid) and caprylic acid (octanoic acid)

^*** polyoxyether of lauryl alcohol with 6 EO units per molecule on average

^**** polyoxyether of a mixture of cetyl alcohol and stearyl alcohol with 12 EO units per molecule (on average)

^***** Monoester of sorbitol and lauric acid with on average 20 EO units per molecule (Polyoxyethylen(20)-sorbitan-monolaurat) Performance of the Polymer Dispersions made

The following formulations were prepared containing either Dispersion D or Carbomer (crosslinked polyacrylic acid) or Polyurethane-39 (copolymer of PEG-140 and hexamethylene diisocyanate endcapped with different alkoxylated fatty alcohols [C12-14 + 10EO, C16-18 + 1 1 EO and C18-20 + 1 1 EO]; abbreviation: PU-39) as thickening agent. The pH value was adjusted with citric acid and sodium hydoxide solution.

^* mixture of cetyl alchol and stearyl aclcohol

^** fatty acids obtained from coconuts esteriefied with a mixture of capric acid (decanoic acid) and caprylic acid (octanoic acid)

Sodium Chloride 2,0 % 2,0 % 2,0 % 2,0 %

Thickening agent (active

0,5 % 0,5 % 0,5 % 0,0 % matter)

Water ad 100% ad 100% ad 100% ad 100%

Viscosity

(measured with Brookfield

224000 mPas 33000 mPas 72200 mPas 6000 mPas RVT viscometer, spindle T-C,

4rpm at 23°C)

^* polyoxyether of a mixture of cetyl alcohol and stearyl alcohol with on average 6 EO units per molecule

^** polyoxyether of a mixture of cetyl alcohol and stearyl alcohol with on average 25 EO units per molecule

^*** Ester of a mixture of cetyl alcohol / stearyl alcohol with 2-ethylhexanoic acid (octanoic acid).

Formulations A, C and D show that in each case the polymer according to the present invention is the most effective thickening agent resulting in the highest viscosity in comparison with the conventional thickening agents. Furthermore the formulations demonstrate the polymers according to the present invention can be combined with several cosmetic ingredients including anionic surfactants (formulation A) and nonionic surfactants (formulations C and D). Formulation C contains 2 % by weight of sodium chloride and demonstrates that the polymers according to the present invention have a high electrolyte tolerance.

Examples Comparing Polymers with Acrylic Acid and Methacrylic Acid (according to the present invention) to Polymers with Acrylic Acid only or Methacrylic Acid only (comparison examples): Samples A, B, F, G and H

The present invention targets the use of polymers in cosmetic formulations. The structures are intended to optimize a) the viscosity performance at lower pH values (around 5) and b) the electrolyte tolerance of the cosmetic formulation. The lower pH values are of increasing interest because of the trend towards acid based preservatives - e.g. benzoic acid, sorbis acid resp. their salts that usually need pH of 5 or lower - and the natural pH of skin. Increased electrolyte tolerance is a common demand for several applications - not only in the cosmetic field.

Samples A and B

Viscosities measured with: Brookfield RVT, 4rpm, spindle TC, Helipath at 23°C Sample A is prepared with acrylic acid, for process reasons combined with methyl methacrylate (MMA). Sample B combines acrylic acid with methacrylic acid (MAA).

In pure water almost no difference is detectable. In the critical formulations C and I the advantage is obvious and relevant.

Table 5: Formulation C

Table 6: Formulation I

Samples F, G and H

Viscosities measured with: Brookfield RVT, 4rpm, spindle TC, Helipath @ 23°C

Samples prepared with AA only or combining AA with MAA are processable. In pure water their performance differs only slightly. In the critical formulation C the difference is obvious and relevant.

A composition only based on MAA (Sample H) was not producible. The batch got solid during synthesis.

Samples M and O: Comparison of different processes for making polymers

Viscosities measured with: Brookfield RVT, 4rpm, spindle TC, Helipath @ 23°C

Regarding the incorporation time for the formulations mentioned in Table 4: It takes more than 240 minutes to achieve a homogeneous, aqueous dispersion out of the dried powder, whereas it takes only less than 5 minutes to achieve a homogeneous, aqueous dispersion with the polymer-in-oil suspension. In both cases 300g of aqueous formulation were processed in a 400ml beaker, stirring with a propeller stirrer (~5cm diameter) at 300rpm and a temperature of 25°C +/- 2°C.