Source: {"pile_set_name": "USPTO Backgrounds"}

The invention relates to a composition for the oxidation dyeing of keratin fibres, in particular of human keratin fibres such as the hair, comprising 2-n-propyl-para-phenylenediamine, in combination with at least one meta-phenylenediamine, as well as to the dyeing process using this composition.
It is known to dye keratin fibres, and in particular human hair, with dye compositions containing oxidation dye precursors, in particular ortho or para-phenylenediamines, or ortho or para-aminophenols, which are generally referred to as oxidation bases. The oxidation dye precursors, or oxidation bases, are colourless or weakly coloured compounds which, when combined with oxidizing products, may give rise to coloured compounds and dyes by a process of oxidative condensation.
It is also known that the shades obtained with oxidation bases may be varied by combining them with couplers or coloration modifiers, it being possible for the latter to be chosen in particular from aromatic meta-diamines, meta-aminophenols and meta-diphenols.
The variety of molecules used as oxidation bases and couplers makes it possible to obtain a wide range of colours.
The so-called xe2x80x9cpermanentxe2x80x9d coloration obtained by means of these oxidation dyes seeks to satisfy a certain number of requirements. Thus, it is desired to have no toxicological drawbacks and to allow shades of the desired intensity to be obtained and to have good staying power with respect to external agents (light, inclement weather, washing, permanent-waving, perspiration and rubbing).
It is also desired that the dyes allow white hairs to be covered and, lastly, to be as unselective as possible, that is to say to allow the smallest possible differences in coloration to be produced over the entire length of the same keratin fibre, which may indeed be differently sensitized (i.e. damaged) between its tip and its root.
Compositions for the oxidation dyeing of keratin fibres, containing at least one meta-phenylenediamine derivative as coupler, in combination with at least one oxidation dye precursor of para-phenylenediamine type or derivatives, have already been proposed. However, the colorations obtained with these compositions are not entirely satisfactory, in particular regarding the staying power of these colorations with respect to the various attacking factors to which the hair may be subjected, and in particular shampoos.
The present invention is aimed at proposing novel compositions for the oxidation dyeing of keratin fibres, and in particular of human keratin fibres such as the hair, which have very good dyeing properties.
Thus, the inventor has just discovered that it is possible to obtain novel dyes of particularly good staying power, which lead to intense colorations, by combining:
at least one oxidation base selected from 2-n-propyl-para-phenylenediamine and acid addition salts thereof, and
at least one coupler selected from meta-phenylenediamines of formula (I) defined below and acid addition salts thereof.
This discovery forms the basis of the present invention.
The first subject of the invention is thus a composition for the oxidation dyeing of keratin fibres, and in particular of human keratin fibres such as the hair, characterized in that it comprises, in a medium which is suitable for dyeing:
at least one oxidation base selected from 2-n-propyl-para-phenylenediamine and acid addition salts thereof, and
at least one coupler selected from meta-phenylenediamines of formula (I) below and acid addition salts thereof: 
wherein:
R1 represents a hydrogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl or C2-C4 polyhydroxyalkyl radical;
R2 and R3, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkoxy or C2-C4 polyhydroxyalkoxy radical;
R4 represents a hydrogen atom or a C1-C4 alkoxy, C1-C4 aminoalkoxy, C1-C4 monohydroxyalkoxy or C2-C4 polyhydroxyalkoxy radical or a 2,4-diamino-phenoxyalkoxy radical.
As demonstrated by the examples below, the colorations obtained with the above compositions are of good dyeing power and have excellent properties of staying power both with regard to atmospheric agents such as light and bad weather and with regard to perspiration and the various treatments to which the hair may be subjected (shampooing, permanent-waving). These properties are particularly noteworthy, especially regarding the staying power of the colorations obtained with respect to shampooing.
The subject of the invention is also a process for the oxidation dyeing of keratin fibres using this composition.
The addition salts with an acid which may be used within the context of the dye compositions of the invention may be chosen in particular from hydrochlorides, hydrobromides, sulphates and tartrates.
Among the meta-phenylenediamines of formula (I) above which may be mentioned more particularly are meta-phenylenediamine, 3,5-diamino-1-ethyl-2-methoxy-benzene, 3,5-diamino-2-methoxy-1-methylbenzene, 2,4-diamino-1-ethoxybenzene, 1,3-bis(2,4-diaminophenoxy)propane, bis(2,4-diaminophenoxy)methane, 1-(xcex2-aminoethyloxy)-2,4-diaminobenzene, 2-amino-1-(xcex2-hydroxyethyloxy)-4-methylaminobenzene, 2,4-diamino-1-ethoxy-5-methylbenzene, 2,4-diamino-5-(xcex2-hydroxyethyloxy)-1-methylbenzene, 2,4-diamino-1-(xcex2,xcex3-dihydroxypropyloxy)benzene, 2,4-diamino-1-(xcex2-hydroxyethyloxy)benzene and 2-amino-4-N-(xcex2-hydroxyethyl)amino-1-methoxybenzene, and the addition salts thereof with an acid.
The 2-n-propyl-para-phenylenediamine and/or the addition salt or salts of this compound with an acid preferably represent from 0.0005 to 10% by weight approximately relative to the total weight of the dye composition, and even more preferably from 0.05 to 7% by weight approximately.
The meta-phenylenediamine(s) of formula (I) in accordance with the invention preferably represent(s) from 0.0001 to 5% by weight approximately relative to the total weight of the dye composition, and even more preferably from 0.005 to 3% by weight approximately.
The appropriate medium for the dyeing (or the support) generally comprises water or a mixture of water and at least one organic solvent to solubilize the compounds which would not be sufficiently soluble in water. Organic solvents which may be mentioned, for example, are C1-C4 lower alkanols such as ethanol and isopropanol; glycerol; glycols and glycol ethers such as 2-butoxyethanol, propylene glycol, diethylene glycol monoethyl ether and monomethyl ether, and aromatic alcohols such as benzyl alcohol or phenoxyethanol, similar products and mixtures thereof.
The solvents may be present in proportions preferably approximately from 1 to 40% by weight relative to the total weight of the dye composition, and even more preferably approximately 5 to 30% by weight.
The pH of the dye composition as described above generally ranges approximately from 5 to 12. It may be adjusted to the desired value using acidifying or basifying agents usually used in the dyeing of keratin fibres.
Among the acidifying agents which may be mentioned, by way of example, are inorganic or organic acids such as hydrochloric acid, orthophosphoric acid, carboxylic acids such as tartaric acid, citric acid and lactic acid, and sulphonic acids.
Among the basifying agents which may be mentioned, by way of example, are aqueous ammonia, alkaline carbonates, alkanolamines such as mono-, di- and triethanolamines and derivatives thereof, sodium hydroxide, potassium hydroxide and the compounds of formula (II) below: 
in which R is a propylene residue optionally substituted with a hydroxyl group or a C1-C4 alkyl radical; R5, R6, R7 and R8, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl or C1-C4 hydroxyalkyl radical.
The dye composition in accordance with the invention may also contain, in addition to the dyes defined above, other oxidation bases and/or other couplers and/or direct dyes, especially in order to modify the shades or to enrich them with glints.
The dye composition according to the invention may also include various adjuvants used conventionally in compositions for dyeing the hair, such as anionic, cationic, nonionic, amphoteric or zwifterionic surfactants or mixtures thereof, anionic, cationic, nonionic, amphoteric or zwitterionic polymers or mixtures thereof, inorganic or organic thickeners, antioxidants, penetration agents, sequestering agents, fragrances, buffers, dispersing agents, conditioners such as, for example, silicones, film-forming agents, preserving agents and opacifying agents.
Obviously, a person skilled in the art will take care to select this or these optional complementary compound(s) such that the advantageous properties intrinsically associated with the dye composition in accordance with the invention are not, or are substantially