Method for dyeing keratin fibres, comprising the application of an oxidative pre-treatment agent and a dye comprising direct dyes

Abstract

The present invention relates to a method for dyeing keratin fibres, in particular human hair, comprising the following steps: - applying a pre-treatment agent (V) to the keratin fibres, the pre-treatment agent (V-Ox) containing at least one oxidizing agent; and - applying a dye (F) to the keratin fibres, the dye containing, in a cosmetic carrier (F-DZ), at least one direct dye.

Description

[0001] Process for dyeing keratin fibers comprising the application of an oxidative pretreatment agent and a dyeing agent with direct dyes

[0002] The present application relates to a cosmetic method for coloring keratin fibers, in particular human hair, comprising the application of a pretreatment agent and a colorant. The pretreatment agent contains at least one oxidizing agent (V-Ox), and the colorant contains at least one direct dye (F-DZ).

[0003] Altering the shape and color of keratinous material, especially human hair, represents an important area of ​​modern cosmetics. Depending on the coloring requirements, hair coloring specialists are familiar with various coloring systems. For permanent, intense colorings with good fastness properties and good gray coverage, oxidation dyes are typically used. Such dyes contain oxidation dye precursors, so-called developer components, and coupler components, which, under the influence of oxidizing agents such as hydrogen peroxide, form the actual dyes. Oxidation dyes are characterized by very long-lasting coloring results.

[0004] When using direct dyes, fully formed dyes diffuse from the dyeing agent into the hair fiber. Compared to oxidative hair coloring, the colors obtained with direct dyes are less durable and wash out more quickly. Colorations with direct dyes typically remain on the hair for between 5 and 20 washes. Therefore, there is still room for improvement regarding the fastness properties of colorations produced with direct dyes.

[0005] It was the object of the present invention to find a dyeing process based on direct dyes which provides dyeings with improved wash fastness.

[0006] Surprisingly, it has now been found that the fastness properties of hair dyed with direct dyes can be particularly improved if the hair is pretreated with an oxidative pretreatment agent (V) before dyeing.

[0007] The subject of the present application is a method for dyeing keratin fibers, in particular human hair, comprising the following steps: application of a pretreatment agent (V) to the keratin fibers, wherein the pretreatment agent

[0008] (V-Ox) contains at least one oxidizing agent, and

[0009] - application of a coloring agent (F) to the keratin fibers, wherein the coloring agent is contained in a cosmetic carrier

[0010] (F-DZ) contains at least one direct dye.

[0011] Hair dyed using the above-mentioned method was characterized by an intense color result with improved washfastness. Furthermore, the hair dyed this way was very evenly colored throughout its entire length, regardless of the degree of damage.

[0012] The advantage of the process according to the invention lies primarily in the fact that the user can continue to use his usual Level 1 coloration and can significantly improve its washfastness through the combined use with the pretreatment agent (V).

[0013] Keratin fibers

[0014] Keratin fibers include hair, wool, and fur. Human hair is particularly preferred as keratin fibers.

[0015] Process for coloring keratin fibers

[0016] In the context of this invention, the term "coloring process" refers to the coloring of keratin fibers, particularly hair, using direct dyes. Colorants of this type can also be referred to as Level 1 colorants or Level 1 colorants.

[0017] Pretreatment agent (V)

[0018] Before applying the coloring agent (F), the pretreatment agent (V) is applied to the keratin fibers, in particular the hair. The pretreatment agent described below is the ready-to-use pretreatment agent that can be applied directly to the keratin fibers or hair. The pretreatment agent (V) is characterized by containing at least one oxidizing agent (V-Ox).

[0019] By acting on the keratin fibers, the oxidizing agent frees them of adhering components that could interfere with the coloring process. They swell slightly, and the cuticle layer opens. This allows the direct dyes applied in the subsequent coloring step to penetrate particularly well and deeply into the keratin fibers.

[0020] Oxidizing agent (V-Ox) in the pretreatment agent (V) As an essential component of the invention, the pretreatment agent (V) contains at least one oxidizing agent (V-Ox).

[0021] Oxidizing agents are substances with an oxidizing effect. Examples of oxidizing agents commonly used in cosmetics include hydrogen peroxide and / or at least one adduct thereof, particularly with inorganic or organic compounds, such as sodium perborate, sodium percarbonate, magnesium percarbonate, sodium percarbonate, polyvinylpyrrolidone n H2O2 (n is a positive integer greater than 0), urea peroxide, and melamine peroxide.

[0022] For use in the process according to the invention, the oxidizing agents from the group consisting of carbamide peroxide, potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate have proven particularly suitable.

[0023] Carbamide peroxide is the adduct of hydrogen peroxide and urea, which is commercially available, for example, in the form of a white crystalline powder. It is a water-soluble crystalline adduct that can be formed by recrystallizing urea with a 30% hydrogen peroxide solution.

[0024] Carbamide peroxide is also referred to in the literature as urea hydrogen peroxide adduct, urea peroxide, perhydrite, percarbamide, or urea peroxide. Carbamide peroxide has the molecular formula CH6N2O3 and the CAS number 124-43-6.

[0025] Carbamide peroxide can be purchased commercially from Thermo Scientific, for example.

[0026] In a further embodiment, persulfates and / or their salts can also be used with particular preference as oxidizing agents in the pretreatment agent (V). The use of one or more persulfates from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate, and sodium peroxodisulfate is very particularly preferred.

[0027] Ammonium peroxodisulfate, which can also be called ammonium persulfate, is the persulfate with the molecular formula (NH4)2S2Oa.

[0028] Potassium peroxodisulfate, which can also be called potassium persulfate, is the persulfate with the molecular formula K2S2O8.

[0029] Sodium peroxodisulfate, which can alternatively also be referred to as sodium persulfate, is understood to mean the persulfate with the molecular formula Na2S2Os. In a particularly preferred embodiment, a process according to the invention is therefore characterized in that the pretreatment agent (V) contains one or more oxidizing agents (V-Ox) from the group consisting of carbamide peroxide, potassium peroxodisulfate, ammonium peroxodisulfate, and sodium peroxodisulfate.

[0030] During the experiments leading to this invention, it was found that a significant and effective improvement in washfastness could be achieved, particularly when a pretreatment agent (V) containing a combination of various oxidizing agents was used in the process according to the invention. Particularly good results were obtained when using a pretreatment agent (V) containing the combination of carbamide peroxide (V-Ox1) and at least one peroxodisulfate (V-Ox2) from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate, and sodium peroxodisulfate.

[0031] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0032] (V-Ox2) at least one peroxodisulfate from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate.

[0033] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0034] (V-Ox2) Ammonium peroxodisulfate.

[0035] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0036] (V-Ox2) Potassium peroxodisulfate.

[0037] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0038] (V-Ox2) Sodium peroxodisulfate.

[0039] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0040] (V-Ox2) ammonium peroxodisulfate and potassium peroxodisulfate. In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0041] (V-Ox2) Ammonium peroxodisulfate and sodium peroxodisulfate.

[0042] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0043] (V-Ox2) Potassium peroxodisulfate and sodium peroxodisulfate.

[0044] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-Ox1) carbamide peroxide and

[0045] (V-Ox2) Ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate.

[0046] According to the invention, the oxidative cosmetic pretreatment agent may additionally contain at least one catalyst as an optional ingredient that activates the oxidation of the substrate, such as the melanin present in the keratin material. Such catalysts include, for example, metal ions, iodides, quinones, or certain enzymes.

[0047] Suitable metal ions include Zn 2+ , Cu 2+ , Fe 2+ , Fe 3+ , Mn 2+ , Mn 4+ , Li + , Mg 2+ , Ca 2+ and Al 3+ Zn 2+ , Cu 2+ and Mn 2+The metal ions can, in principle, be used in the form of any physiologically acceptable salt or in the form of a complex compound. Preferred salts are acetates, sulfates, halides, lactates, and tartrates.

[0048] Suitable enzymes include peroxidases, which can significantly enhance the effect of small amounts of hydrogen peroxide. Furthermore, enzymes suitable for the invention are those that generate small amounts of hydrogen peroxide in situ with the aid of atmospheric oxygen and thus biocatalytically activate the oxidation of the dye precursors. Particularly suitable catalysts for the oxidation of dye precursors are the so-called 2-electron oxidoreductases in combination with the specific substrates, e.g.

[0049] Pyranose oxidase and e.g. D-glucose or galactose,

[0050] glucose oxidase and D-glucose,

[0051] Glycerol oxidase and glycerol,

[0052] Pyruvate oxidase and benzoic acid or their salts,

[0053] Alcohol oxidase and alcohol (MeOH, EtOH),

[0054] Lactate oxidase and lactic acid and their salts,

[0055] Tyrosinase oxidase and tyrosine,

[0056] Uricase and uric acid or their salts, choline oxidase and choline,

[0057] Amino acid oxidase and amino acids.

[0058] By selecting the appropriate quantity ranges of oxidizing agent(s) (V-Ox) (or (V-Ox1) and (V-Ox2)) in the pretreatment agent (V), the extent of the influence that the pretreatment agent (V) has on the washfastness of the subsequently applied colorant (F) can be specifically controlled. In this context, it has been shown that the washfastness is better the higher the amount of oxidizing agent used in the pretreatment agent (V). On the other hand, however, the damage to the keratin material or the keratin fibers / hair also increases with increasing amounts of oxidizing agents. In order to find the optimal balance between these two effects, it has proven particularly preferable to use the oxidizing agent(s) in very specific quantity ranges in the pretreatment agent.

[0059] The pretreatment agent according to the invention preferably contains - based on the total weight of the pretreatment agent - 1.0 to 30.0 wt.%, preferably 3.0 to 20.0 wt.%, more preferably 6.0 to 15.0 wt.% and most preferably 8.0 to 15.0 wt.% carbamide peroxide (V-Ox1).

[0060] The pretreatment agent (V) according to the invention preferably contains - based on the total weight of the pretreatment agent - one or more persulfates (V-Ox2) from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate in a total amount of 3.0 to 40.0 wt.%, preferably 3.0 to 30 wt.%, more preferably 6.0 to 20.0 wt.% and most preferably 9.0 to 17.0 wt.%.

[0061] In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent (V) - contains

[0062] (V-Ox1) 1.0 to 30.0 wt.%, preferably 3.0 to 20.0 wt.%, more preferably 6.0 to 15.0 wt.% and most preferably 8.0 to 15.0 wt.% carbamide peroxide, and

[0063] (V-Ox2) one or more peroxodisulfates from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate in a total amount of 1.0 to 40.0 wt.%, preferably 3.0 to 30 wt.%, more preferably 6.0 to 20.0 wt.% and most preferably 9.0 to 17.0 wt.%.

[0064] Cosmetic carrier of the pretreatment agent (V)

[0065] The oxidizing agent(s) (V-Ox) (or (V-Ox1) and (V-Ox2)) are contained in the pretreatment agent (V) in a cosmetic carrier. In principle, various carriers are conceivable as cosmetic carriers for the pretreatment agent (V), such as an aqueous, alcoholic or aqueous-alcoholic carrier. The carrier can also be a cream, emulsion, a paste or even a surfactant-containing foaming solution, such as a shampoo, foam aerosol, a foam formulation or other preparation suitable for application to the hair. Water is the most common of all solvents in cosmetic products, therefore, in principle, water can also be used as the main ingredient as a cosmetic carrier.

[0066] However, the work leading to this invention has shown that the nature of the cosmetic carrier in the pretreatment agent (V) can have a major influence on the lightening and damage associated with the use of the oxidizing agent(s).

[0067] If, for example, the combination of carbamide peroxide (V-Ox1) and peroxodisulfates (V-Ox2) was used in pretreatment agents (V) with a very high water content, increased lightening and, associated with this, greater hair damage was observed. The improvement in the washfastness of the coloring performance could indeed be achieved with the process according to the invention, but the hair was also damaged more severely. Surprisingly, hair damage could be massively reduced by using a cosmetic carrier with a higher solvent content. It is assumed that the presence of the solvent either slows down the dissolution or decomposition of the carbamide peroxide or inhibits the reaction of carbamide peroxide with persulfates to such an extent that the inner part (i.e. the cortex) of the hair is less oxidatively changed, the surface orthe cuticle is nevertheless modified or opened to such an extent that direct dyes can penetrate or adhere there better.

[0068] Solvents from the group of glycerol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, ethanol, isopropanol, dipropylene glycol, diethylene glycol monoethyl ether, phenoxyethanol, benzyl alcohol, poly-Ci-Ce-alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate have proven particularly suitable.

[0069] In a further preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains at least one solvent from the group consisting of glycerol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, ethanol, isopropanol, dipropylene glycol, diethylene glycol monoethyl ether, phenoxyethanol, benzyl alcohol, poly-Ci-Ce-alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate.

[0070] The solvent(s) are preferably used in the pretreatment agent (V) in amounts that are sufficiently high to slow down the dissolution or interaction of the carbamide peroxide, but on the other hand are so low that the product is not excessively polluted with solvents. The pretreatment agent (V) preferably contains - based on the total weight of the pretreatment agent (V) - one or more solvents from the group consisting of glycerol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, ethanol, isopropanol, dipropylene glycol, diethylene glycol monoethyl ether, phenoxyethanol, benzyl alcohol, poly-Ci-Ce-alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate in a total amount of 3.0 to 80% by weight, preferably of 5.0 to 60.0% by weight, more preferably of 9.0 to 40.0% by weight and very particularly preferably of 12.0 to 25.0% by weight.

[0071] In a further very particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent (V) - contains one or more solvents from the group consisting of glycerol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, ethanol, isopropanol, dipropylene glycol, diethylene glycol monoethyl ether, phenoxyethanol, benzyl alcohol, poly-Ci-Ce-alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate in a total amount of 3.0 to 80 wt.%, preferably from 5.0 to 60.0 wt.%, more preferably from 9.0 to 40.0 wt.% and very particularly preferably from 12.0 to 25.0 wt.%.

[0072] Most preferably, the pretreatment agent (V) contains glycerol and 1,2-propanediol.

[0073] Explicitly most preferably, the pretreatment agent (V) contains - based on the total weight of the pretreatment agent (V) - 12.0 to 25.0 wt.% glycerol and 1.0 to 7.0 wt.% 1,2-propanediol.

[0074] Instead of or in addition to the aforementioned solvents, the pretreatment agent (V) can also contain one or more polyalkylene glycols. The polyalkylene glycols reduce the polarity of the cosmetic carrier. Increasing the proportion of polyalkylene glycol(s) in the pretreatment agent (V) also resulted in a reduction in hair damage and lightening of the pretreated keratin fibers. In this way, the subsequent application of the colorant (F) improved the washfastness and uniformity of the colorings without excessively damaging the keratin fibers and without lightening their original hair color. In this context, it is suspected that the dissolution of the carbamide peroxide or its reaction with the persulfates is also reduced by the polyalkylene glycols, causing the oxidizing agents to react with a time delay or only with the surface of the keratin fibers.

[0075] Polyalkylene glycols which are particularly suitable according to the invention are, for example, ethylene glycols of the formula (EG-V) where x is an integer from 1 to 10,000, preferably an integer from 2 to 500, more preferably an integer from 3 to 100 and most preferably an integer from 5 to 30.

[0076] The ethylene glycols of formula (EG-V) are protic substances with at least one hydroxyl group, which, due to their repeating unit -CH2-CH2-O-, can also be referred to as polyethylene glycols, provided x represents a value of at least 2. In the alkylene glycols of formula (EG-V), x represents an integer from 1 to 10,000.

[0077] Depending on their chain length, polyethylene glycols are liquid or solid, water-soluble polymers. Polyethylene glycols with a molecular weight between 200 g / mol and 400 g / mol are non-volatile liquids at room temperature. PEG 600 has a melting range of 17 to 22 °C and thus a paste-like consistency. With molecular weights above 3000 g / mol, PEGs are solid substances and are marketed as flakes or powders.

[0078] The use of low-molecular-weight alkylene glycols (or polyethylene glycols) has proven particularly suitable for achieving the object of the invention. For low-molecular-weight alkylene glycols (or polyethylene glycols) within the meaning of the present invention, x1 represents an integer from 1 to 100, preferably an integer from 1 to 80, more preferably an integer from 2 to 60, even more preferably an integer from 3 to 40, even more preferably an integer from 4 to 20, and most preferably an integer from 6 to 15.

[0079] A particularly preferred low-molecular-weight polyethylene glycol is PEG-8. PEG-8 contains an average of 8 ethylene glycol units (x1 = 8), has an average molecular weight of 400 g / mol, and bears the CAS number 25322-68-3. PEG-8 is also known as PEG 400 and is commercially available, for example, from APS.

[0080] Other suitable low molecular weight polyethylene glycols include PEG-6, PEG-7, PEG-9 and PEG-10.

[0081] Another suitable polyethylene glycol is PEG-32. PEG-32 contains 32

[0082] Ethylene glycol units (x1 = 32), has an average molecular weight of 1500 g / mol, and carries the CAS number 25322-68-3. PEG-32 is also known as PEG 1500 and can be purchased commercially, for example, from Clariant.

[0083] The polyalkylene glycol(s), in particular the polyethylene glycols of formula (EG-V), are preferably used in the pretreatment agent (V) in amounts that are sufficiently high to slow the dissolution or interaction of the carbamide peroxide, but on the other hand are low enough that the product is not excessively polluted with solvents. The pretreatment agent (V) preferably contains - based on the total weight of the pretreatment agent (V) - one or more ethylene glycols of formula (EG-V) in a total amount of 1.0 to 80% by weight, preferably 1.5 to 60.0% by weight, more preferably 3.0 to 40.0% by weight, and most preferably 4.5 to 10.0% by weight.

[0084] In a further very particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent - contains one or more ethylene glycols of the formula (EG-V) in a total amount of 1.0 to 80.0 wt.%, preferably 1.5 to 60.0 wt.%, more preferably 3.0 to 40.0 wt.% and very particularly preferably 4.5 to 10.0 wt.%, where x is an integer from 1 to 10,000, preferably an integer from 2 to 500, more preferably an integer from 3 to 100 and most preferably an integer from 5 to 30.

[0085] Most preferably, the pretreatment agent (V) contains at least one solvent from the group described above and at least one polyethylene glycol of the formula (EG-V).

[0086] In a further particularly preferred embodiment, the pretreatment agent (V) according to the invention contains

[0087] - one or more solvents from the group consisting of glycerol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, ethanol, isopropanol, dipropylene glycol, diethylene glycol monoethyl ether, phenoxyethanol, benzyl alcohol, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate, and

[0088] - one or more ethylene glycols of the formula (EG-V) described above. In order to inhibit the decomposition of the oxidizing agents, in particular the carbamide peroxide, or to stabilize the oxidizing agents, it has also proven particularly preferable to adjust the water content in the pretreatment agent to a medium to low range. Therefore, it is particularly advantageous if the pretreatment agent (V) contains, based on the total weight of the pretreatment agent (V), 5.0 to 70.0 wt.%, preferably 10.0 to 60.0 wt.%, more preferably 15.0 to 50.0 wt.%, and very particularly preferably 20.0 to 40.0 wt.% of water.

[0089] In a further very particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent (V) - contains 5.0 to 70.0 wt.%, preferably 10.0 to 60.0 wt.%, more preferably 15.0 to 50.0 wt.% and very particularly preferably 20.0 to 40.0 wt.% of water.

[0090] Alkalizing agent (V-alkali) in the pretreatment agent (V)

[0091] As an optional component, the pretreatment agent (V) may also contain at least one alkalizing agent (V-alkali). The alkalizing agent(s) may be inorganic and / or organic.

[0092] Inorganic alkalizing agents such as alkali metal carbonates and / or alkaline earth metal carbonates are particularly suitable. Examples of suitable alkali metal carbonates include sodium carbonate and potassium carbonate. Examples of particularly suitable alkaline earth metal carbonates include magnesium carbonate and calcium carbonate.

[0093] Good results were also obtained when the pretreatment agent (V) contained at least one alkali metal hydroxide as the alkalizing agent (V-alkali). Examples of well-suited alkali metal hydroxides include sodium hydroxide and potassium hydroxide. Furthermore, good results were obtained when the pretreatment agent (V) contained at least one alkaline earth metal hydroxide as the alkalizing agent (V-alkali). Examples of well-suited alkaline earth metal hydroxides include magnesium hydroxide, potassium hydroxide, and barium hydroxide.

[0094] Good results were also obtained when the pretreatment agent (V) contained at least one alkali metal silicate and / or alkali metal metasilicate as an alkalizing agent (V-alkali). Suitable alkali metal silicates include sodium silicate and potassium silicate. Suitable alkali metal metasilicates include sodium metasilicate and potassium metasilicate.

[0095] The use of ammonia as an alkalizing agent is also very suitable. Furthermore, the pretreatment agent (V) can contain at least one C2-C6 alkanolamine as an alkalizing agent. The alkanolamines that can be used in this context can be selected, for example, from the group of primary amines with a C2-C6 alkyl parent structure bearing at least one hydroxyl group. Preferred alkanolamines are selected from the group consisting of 2-aminoethan-1-ol (monoethanolamine), 3-aminopropan-1-ol, 4-aminobutan-1-ol, 5-aminopentan-1-ol, 1-aminopropan-2-ol, 1-aminobutan-2-ol, 1-aminopentan-2-ol, 1-aminopentan-3-ol, 1-aminopentan-4-ol, 3-amino-2-methylpropan-1-ol, 1-amino-2-methylpropan-2-ol, 3-aminopropan-1,2-diol, 2-amino-2-methylpropan-1,3-diol.

[0096] The use of basic amino acids as alkalizing agents (V-alkali) is also quite possible. An amino acid within the meaning of the invention is an organic compound that contains at least one protonatable amino group and at least one -COOH or -SO 3 H group in its structure. Preferred amino acids are aminocarboxylic acids, in particular α-(alpha)-aminocarboxylic acids and α-aminocarboxylic acids, with α-aminocarboxylic acids being particularly preferred. For the purposes of the invention, basic amino acids are those amino acids that have an isoelectric point pI of greater than 7.0.

[0097] Basic α-aminocarboxylic acids contain at least one asymmetric carbon atom. Within the scope of the present invention, both possible enantiomers can be used equally as specific compounds or as mixtures thereof, particularly as racemates. However, it is particularly advantageous to use the naturally occurring isomer form, usually in the L-configuration.

[0098] The basic amino acids are preferably selected from the group consisting of arginine, lysine, ornithine, and histidine, particularly preferably arginine and lysine. In another particularly preferred embodiment, an agent according to the invention is characterized in that the alkalizing agent is a basic amino acid from the group consisting of arginine, lysine, ornithine, and / or histidine.

[0099] In a preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains at least one alkalizing agent (V-alkali) selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal silicates, alkali metal metasilicates, alkaline earth metal silicates, alkaline earth metal metasilicates, alkali metal carbonates and alkaline earth metal carbonates, ammonia, C2-C6 alkanolamines and basic amino acids.

[0100] If the pretreatment agent (V) contains water and one or more alkalizing agents, the latter influence the pH value of the pretreatment agent. It has been found that alkaline pH values, in particular, have a beneficial effect on the dyeing performance achievable in the process and the fastness properties of the dyeings.

[0101] For this reason, it is preferred that the pretreatment agent (V) contains water and has a pH of 3.0 to 12.0, preferably of 3.4 to 11.5, more preferably of 4.0 to 9.0 and most preferably of 4.0 to 7.0.

[0102] The pH value can be measured using the usual methods known from the state of the art, such as pH measurement using glass electrodes via combination measuring chains or using pH indicator paper.

[0103] In a further very particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) has a pH of 2.0 to 11.5, preferably of 3.4 to 10.0, more preferably of 4.0 to 9.0 and very particularly preferably of 4.0 to 7.0.

[0104] To fine-tune the desired pH value, it may be necessary to add one or more acidifying agents to the pretreatment agent (V) in addition to the alkalizing agent. The pH values ​​used in the present invention are pH values ​​measured at a temperature of 22°C.

[0105] Dye (F)

[0106] After the application of the pretreatment agent (V), the keratin fibers, preferably human hair, are colored with a colorant (F).

[0107] The colorant (F) can be applied to moistened or dry keratin fibers. It can be applied using a brush, a nozzle, or a gloved hand, for example. After a contact time of 5 to 60 minutes, preferably 10 to 45 minutes, the colorant can be rinsed out with water or with water and shampoo.

[0108] The colorant (F) is understood to mean the ready-to-use colorant which contains at least one direct dye (F-DZ) and can thus be applied directly to the keratin fibers in the form in which it is presented.

[0109] Direct dyes (F-DZ) in the dye

[0110] The colorant (F) contains at least one direct dye (F-DZ). These are dyes that are absorbed directly into the hair and do not require an oxidative process to develop the color. Direct dyes are typically nitrophenylenediamines, nitroaminophenols, azo dyes, anthraquinones, triarylmethane dyes, or indophenols.

[0111] The direct dyes according to the present invention have a solubility in water (760 mmHg) at 25°C of more than 0.5 g / L and are therefore not considered pigments. Preferably, the direct dyes according to the present invention have a solubility in water (760 mmHg) at 25°C of more than 1.0 g / L.

[0112] The water solubility of direct dyes can be determined, for example, as follows: 0.1 g of the direct dye is placed in a beaker. A stir bar is attached. Then 100 ml of water is added. This mixture is heated to 25 °C on a magnetic stirrer while stirring. It is stirred for 60 minutes. The aqueous mixture is then visually assessed. If undissolved residues remain, the amount of water is increased – for example, in 10 ml increments. Water is added until the used amount of dye has completely dissolved. If the dye-water mixture cannot be assessed visually due to the high intensity of the dye, the mixture is filtered. If a portion of undissolved dye remains on the filter paper, the solubility test is repeated using a larger amount of water.If 0.1 g of the anionic direct dye dissolves in 100 ml of water at 25 °C, the solubility of the dye is 1.0 g / L.

[0113] Direct dyes can be divided into cationic, anionic, and non-ionic direct dyes. When used in the process according to the invention, good color results with outstanding fastness properties were achieved, particularly with cationic dyes (F-DZ). The greatest improvement in washfastness was observed when the hair was dyed using the process according to the invention with at least one cationic direct dye. Therefore, it is particularly preferred if the colorant (F) contains at least one cationic direct dye (F-DZ).

[0114] In a further embodiment, the method according to the invention for dyeing the keratin fibers is characterized in that the coloring agent (F) contains at least one direct dye (F-DZ) from the group of cationic, anionic and / or non-ionic direct dyes, particularly preferably from the group of cationic direct dyes.

[0115] Preferred cationic substantive dyes are HC Blue 16, Basic Blue 7, Basic Blue 26, Basic Violet 2 and Basic Violet 14, Basic Yellow 57, Basic Red 76, Basic Blue 16, Basic Blue 347 (Cationic Blue 347 / Dystar), HC Blue No. 16, Basic Blue 99, Basic Brown 16, Basic Brown 17, Yellow 87, Basic Orange 31 and Basic Red 51. In a further particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one cationic substantive dye (F-DZ) which is selected from the group consisting of Basic Blue 7, Basic Blue 26, Basic Violet 2 and Basic Violet 14, Basic Yellow 57, Basic Red 76, Basic Blue 16, Basic Blue 347 (Cationic Blue 347 / Dystar), HC Blue No. 16, Basic Blue 99, Basic Brown 16, Basic Brown 17, Yellow 87, Basic Orange 31 and Basic Red 51. 16, Basic Blue 99, Basic Brown 16, Basic Brown 17, Yellow 87, Basic Orange 31 and Basic Red 51 and / or their salts.

[0116] Dyes containing at least one non-ionic direct dye (F-DZ) could also be improved in terms of their wash fastness by using the aftertreatment agent (N).

[0117] Suitable non-ionic direct dyes include non-ionic nitro and quinone dyes and neutral azo dyes. Suitable non-ionic direct dyes are those known under the international designations "Dye Dye" and "Dye Dye" respectively.Handelsnamen HC Yellow 2, HC Yellow 4, HC Yellow 5, HC Yellow 6, HC Yellow 12, HC Orange 1 , Disperse Orange 3, HC Red 1 , HC Red 3, HC Red 10, HC Red 11 , HC Red 13, HC Red BN, HC Blue 2, HC Blue 1 1 , HC Blue 12, Disperse Blue 3, HC Violet 1 , Disperse Violet 1 , Disperse Violet 4, Disperse Black 9 bekannten Verbindungen, sowie 1 ,4-Diamino-2-nitrobenzol, 2-Amino-4-nitrophenol, 1 ,4-Bis-(2-hydroxyethyl)-amino-2-nitro- benzol, 3-Nitro-4-(2-hydroxyethyl)-aminophenol, 2-(2-Hydroxyethyl)amino-4,6-dinitrophenol, 4-[(2- Hydroxyethyl)amino]-3-nitro-1 -methylbenzol, 1-Amino-4-(2-hydroxyethyl)-amino-5-chlor-2- nitrobenzol, 4-Amino-3-nitrophenol, 1-(2'-Ureidoethyl)amino-4-nitrobenzol, 2-[(4-Amino-2- nitrophenyl)amino]-benzoesäure, 6-Nitro-1 ,2,3,4-tetrahydrochinoxalin, 2-Hydroxy-1 ,4-naphtho- chinon, Pikraminsäure und deren Salze, 2-Amino-6-chloro-4-nitrophenol, 4-Ethylamino-3-nitro- benzoesäure und 2-Chlor-6-ethylamino-4-nitrophenol.

[0118] In a further preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one non-ionic dye (F-DZ) which is selected from the group consisting of HC Yellow 2, HC Yellow 4, HC Yellow 5, HC Yellow 6, HC Yellow 12, HC Orange 1, Disperse Orange 3, HC Red 1, HC Red 3, HC Red 10, HC Red 11, HC Red 13, HC Red BN, HC Blue 2, HC Blue 11, HC Blue 12, Disperse Blue 3, HC Violet 1, Disperse Violet 1, Disperse Violet 4, Disperse Black 9, 1,4-diamino-2-nitrobenzene, 2-amino-4-nitrophenol, 1,4-bis-(2-hydroxyethyl)-amino-2-nitrobenzene, 3-Nitro-4-(2-hydroxyethyl)-aminophenol, 2-(2-hydroxyethyl)-amino-4,6-dinitrophenol, 4-[(2-hydroxyethyl)amino]-3-nitro-1-methylbenzene, 1-amino-4-(2-hydroxyethyl)-amino-5-chloro-2-nitrobenzene, 4-amino-3-nitrophenol, 1-(2'-Ureidoethyl)amino-4-nitrobenzene, 2-[(4-amino-2-nitrophenyl)amino]-benzoic acid, 6-nitro-1,2,3,4-tetrahydroquinoxaline, 2-hydroxy-1,4-naphthoquinone,Picramic acid and its salts, 2-amino-6-chloro-4-nitrophenol, 4-ethylamino-3-nitrobenzoic acid, and 2-chloro-6-ethylamino-4-nitrophenol. Suitable anionic direct dyes are the compounds known by the international names or trade names Bromophenol Blue, Tetrabromophenol Blue, Acid Yellow 1, Yellow 10, Acid Yellow 23, Acid Yellow 36, Acid Orange 7, Acid Red 33, Acid Red 52, Pigment Red 57:1, Acid Blue 7, Acid Green 50, Acid Violet 43, Acid Black 1, and Acid Black 52.

[0119] In a further preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one anionic direct dye (F-DZ) which is selected from the group consisting of bromophenol blue, tetrabromophenol blue, Acid Yellow 1, Yellow 10, Acid Yellow 23, Acid Yellow 36, Acid Orange 7, Acid Red 33, Acid Red 52, Acid Blue 7, Acid Green 50, Acid Violet 43, Acid Black 1 and Acid Black 52 and salts thereof.

[0120] The direct dye(s), in particular the cationic direct dye(s), can be used in the colorant (F) in various amounts depending on the desired color intensity. Particularly good results have been obtained when the colorant (F) contains one or more direct dyes in a total amount of 0.0001 to 10.0 wt. %, preferably 0.1 to 5.0 wt. %, more preferably 0.2 to 2.5 wt. %, and most preferably 0.25 to 1.5 wt. %, based on the total weight of the colorant (F).

[0121] In a further preferred embodiment, a process according to the invention is characterized in that the colorant (F) - based on the total weight of the colorant (F) - contains one or more direct dyes (F-DZ) in a total amount of 0.0001 to 10.0 wt.%, preferably 0.1 to 5.0 wt.%, more preferably from 0.2 to 2.5 wt.% and very particularly preferably from 0.25 to 1.5 wt.%.

[0122] In a further preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains - based on the total weight of the colorant (F) - one or more cationic direct dyes (F-DZ) in a total amount of 0.0001 to 10.0 wt. %, preferably 0.1 to 5.0 wt. %, more preferably 0.2 to 2.5 wt. %, and most preferably 0.25 to 1.5 wt. %. Other ingredients in the colorant (F)

[0123] In addition to the direct dye(s) (F-DZ), the colorant (F) may optionally also contain other ingredients.

[0124] Thus, the coloring agent (F) can also contain further active ingredients, auxiliaries and additives, such as, for example, cationic, non-ionic, amphoteric, zwitterionic and / or anionic surfactants, thickening polymers, film-forming polymers, structuring agents such as glucose, maleic acid and lactic acid, hair conditioning compounds such as phospholipids, for example lecithin and cephalins; perfume oils, dimethyl isosorbide and cyclodextrins; fiber structure-improving active ingredients, in particular mono-, di- and oligosaccharides such as, for example, glucose, galactose, fructose, fructose and lactose; dyes for coloring the agent; anti-dandruff active ingredients such as piroctone olamine, zinc omadine and climbazole; amino acids and oligopeptides; protein hydrolysates of animal and / or plant origin, as well as in the form of their fatty acid condensation products or, if appropriate, anionically or cationically modified derivatives; Sunscreens and UV blockers;Active ingredients such as panthenol, pantothenic acid, pantolactone, allantoin, pyrrolidinone carboxylic acids and their salts and bisabolol; polyphenols, in particular hydroxycinnamic acids, 6,7-dihydroxycoumarins, hydroxybenzoic acids, catechins, tannins, leucoanthocyanidins, anthocyanidins, flavanones, flavones and flavonols; ceramides or pseudoceramides; vitamins, provitamins and vitamin precursors; plant extracts; fats and waxes such as fatty alcohols, beeswax, montan wax and paraffins; swelling and penetrating agents such as glycerin, propylene glycol monoethyl ether, carbonates, hydrogen carbonates, guanidines, ureas and primary, secondary and tertiary phosphates; opacifiers such as latex, styrene / PVP and styrene / acrylamide copolymers; Pearlescent agents such as ethylene glycol mono- and distearate and PEG-3 distearate; as well as propellants such as propane-butane mixtures, N2O, dimethyl ether, CO2 and air.

[0125] The expert will select these additional substances based on the desired properties of the agent. Regarding further optional components and the amounts of these components used, reference is expressly made to the relevant manuals known to the expert. The additional active ingredients and excipients are preferably used in the preparations according to the invention in amounts of 0.0001 to 25 wt.%, in particular 0.0005 to 15 wt.%, based on the total weight of the respective agent.

[0126] Sequence of procedural steps

[0127] As previously described, the pretreatment agent (V) is applied before the application of the colorant (F). In this context, it has proven particularly preferable to apply the pretreatment agent (V) to the keratin material, allow it to work for a certain period of time, and then rinse it off with water. The colorant (F) is then applied.

[0128] In other words, the process for dyeing keratin fibers, in particular human hair, preferably comprises the following steps in the order given:

[0129] - application of a pretreatment agent (V) to the keratin fibers, which contains at least one oxidizing agent (V-Ox), and

[0130] - Applying a colorant (F) to the keratin fibers, which contains at least one direct dye (F-DZ), wherein a rinsing step is performed between the application of the pretreatment agent (V) and the colorant (F). In a further preferred embodiment, a method according to the invention is characterized in that the pretreatment agent (V) is applied to the keratin fibers before the colorant (F), and that a rinsing step is performed between the application of the pretreatment agent (V) and the colorant (F).

[0131] In a further embodiment, a method for coloring keratin fibers, in particular human hair, comprising the following steps in the given order:

[0132] (1) Applying the pretreatment agent (V) to the keratin fibers,

[0133] (2) allowing the pretreatment agent applied in step (1) to act on the keratin fibres for a period of 2 to 45 minutes, preferably from 2 to 30 minutes and particularly preferably from 2 to 20 minutes,

[0134] (3) if necessary, rinsing the pretreatment agent (V) with water,

[0135] (4) Applying the colorant (F) to the keratin fibers, and

[0136] (5) allowing the dye applied in step (4) to act on the keratin fibres for a period of 15 seconds to 45 minutes, preferably from 30 seconds to 30 minutes and particularly preferably from 1 to 15 minutes, and

[0137] (6) Rinsing the dye (F) with water,

[0138] In step (1) of the method according to the invention, a pretreatment agent (V) containing at least one oxidizing agent is applied to the hair.

[0139] In the next step, the previously applied pretreatment agent (V) is allowed to act on the keratin fibers. Various exposure times are possible, ranging from 2 to 45 minutes, preferably from 2 to 30 minutes, and particularly preferably from 2 to 20 minutes.

[0140] After the pretreatment agent (V) has been applied to the keratin fibers, it can finally be rinsed out with water in step (3). The pretreatment agent (V) can either be washed out with water alone, i.e., without the aid of a shampoo, or the wash-out process can be assisted by using a shampoo. It is particularly preferred if the pretreatment agent is washed out again after application and exposure.

[0141] Within the scope of another particularly preferred embodiment, a method according to the invention is characterized in that the pretreatment agent (V) is rinsed out with water or with water and a surfactant before the application of the coloring agent (F). In principle, the user can freely choose the period of time between the application of the two agents (V) and (F). By successively applying agents (V) and (F), the washfastness of the color on the keratin fibers can be improved. Furthermore, the color shift caused by washing out is also minimized. To make the best possible use of this effect, agents (V) and (F) are preferably applied as quickly as possible one after the other.

[0142] Therefore, it may be preferable if no further products, such as other conditioners or styling products, are applied between the application of the two products (V) and (F). In this way, the maximum period between the application of the two products (V) and (F) is preferably limited to a maximum of 24 hours.

[0143] It has been found to be preferable if there is a period of maximum 24 hours, preferably maximum 12 hours, more preferably maximum 6 hours and most preferably maximum 3 hours between rinsing out the pretreatment agent (V) with water and applying a colorant (F) to the keratin fibers.

[0144] In a further particularly preferred embodiment, a process according to the invention is characterized in that there is a period of maximum 48 hours, preferably maximum 24 hours, more preferably maximum 12 hours, even more preferably maximum 6 hours and most preferably maximum 3 hours between the application of the pretreatment agent (V) and the application of the colorant (F).

[0145] In steps (4), (5), and (6) of the process, the colorant (F) is applied to the keratin fibers, allowed to act, and then washed out again after a contact time of, for example, 15 seconds to 45 minutes, preferably 30 seconds to 30 minutes, and particularly preferably 1 to 15 minutes. The colorant can be washed out either with water alone or with water and the aid of a shampoo.

[0146] In a further embodiment, a method for coloring keratin fibers, in particular human hair, comprising the following steps in the given order is also very particularly preferred:

[0147] (1) Applying the pretreatment agent (V) to the keratin fibers,

[0148] (2) allowing the pretreatment agent applied in step (1) to act on the keratin fibres for a period of 2 to 45 minutes, preferably from 2 to 30 minutes and particularly preferably from 2 to 20 minutes,

[0149] (3) Rinsing the pretreatment agent (V) with water,

[0150] (4) applying the colorant (F) to the keratin fibers, and (5) allowing the colorant applied in step (4) to act on the keratin fibers for a period of time from 15 seconds to 45 minutes, preferably from 30 seconds to 30 minutes and particularly preferably from 1 to 15 minutes, and

[0151] (6) Rinsing the colorant (F) with water, wherein between steps (3) and (4) there is a period of not more than 48 hours, preferably not more than 24 hours, more preferably not more than 12 hours, even more preferably not more than 6 hours and most preferably not more than 3 hours.

[0152] Preparation of the ready-to-use pretreatment agent by mixing two separately prepared preparations

[0153] As previously described, the pretreatment agent according to the invention is the ready-to-use pretreatment agent (V), which, in its present form, can be applied directly to the keratin fibers or hair. As previously described, the pretreatment agent is characterized by its content of at least one oxidizing agent (V-Ox) and particularly preferably by its content of a combination of carbamide peroxide (V-Ox1) and at least one persulfate (V-Ox2) from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate, and sodium peroxodisulfate.

[0154] In principle, both oxidizing agents from groups (V-Ox1) and (V-Ox2) can be packaged together in one product and made available to the user in this form. However, for reasons of storage stability, it has proven particularly preferable to package the carbamide peroxide (V-Ox1) and the persulfates (V-Ox2) in separate products, so that the user only needs to mix these two products shortly before use to create the ready-to-use pretreatment agent (V).

[0155] In a further embodiment, a method comprising the following steps is therefore particularly preferred:

[0156] (1) Providing a first agent containing carbamide peroxide

[0157] (2) Providing a second agent which contains one or more peroxodisulfates from the group consisting of potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate,

[0158] (3) Mixing the first and second agents to produce a ready-to-use pretreatment agent (V),

[0159] (4) Applying the pretreatment agent (V) prepared in step (3) to the keratin fibers,

[0160] (5) allowing the pretreatment agent (V) applied in step (4) to act on the keratin fibres for a period of 2 to 45 minutes, preferably 2 to 30 minutes and particularly preferably 2 to 20 minutes,

[0161] (6) Rinsing out the pre-treatment agent (V), and (7) applying the colorant (F) to the keratin fibers.

[0162] Following the application of the colorant in step (7), further preferred are the steps

[0163] (8) the dyeing agent (F) applied in step (7) is applied to the keratin fibers for a period of 2 to 60 minutes, preferably 5 to 45 minutes, particularly preferably 10 to 30 minutes, and

[0164] (9) Rinse out the dye.

[0165] A method according to the invention comprising the following steps is also very particularly preferred:

[0166] (1) Providing a first agent containing carbamide peroxide,

[0167] (2) Providing a second agent which contains one or more peroxodisulfates from the group consisting of potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate,

[0168] (3) Mixing the first and second agents to produce a ready-to-use pretreatment agent (V),

[0169] (4) Applying the pretreatment agent (V) prepared in step (3) to the keratin fibers,

[0170] (5) the pretreatment agent (V) applied in step (4) acts on the keratin fibres,

[0171] (6) Rinsing the pretreatment agent (V) with water,

[0172] (7) Applying the colorant (F) after rinsing out the pre-treatment agent (V) to the keratin fibers,

[0173] (8) Exposure of the dye applied in step (7) to the keratin fibres,

[0174] (9) Rinsing the coloring agent (F) with water, wherein the agents (V) and (F) are applied within a time interval of at most 48, preferably at most 16, more preferably at most 6, preferably at most 3 hours.

[0175] If the agents (V) and (F) are applied within a time interval of a maximum of 6, preferably a maximum of 3 hours, this means that after the application of the pretreatment agent (V) a maximum of 6 or 3 hours will pass until the coloring agent (F) is applied.

[0176] The first agent, which contains carbamide peroxide (V-Ox1), is particularly preferably a liquid or flowable agent, most preferably a gel, containing the previously described solvents and / or polyalkylene glycols. The second agent, which contains the peroxodisulfate(s) (V-Ox2), is particularly preferably solid or paste-like.

[0177] The sequence of process steps is governed by the previously described explanations and preferred or particularly preferred embodiments. Improvement of washfastness

[0178] The washfastness of an oxidative color shade refers to the color change of the hair strand dyed with this shade after multiple washes. This color change can involve either a shift in the color toward another shade or a fading of the color. Both color changes are equally undesirable for the user. Color shades with good washfastness show little or no color change even after repeated washes.

[0179] For the purposes of the present invention, an improvement in wash fastness means that keratin fibers dyed with the colorant (F) have a higher color intensity after a defined number of hair washes when the pretreatment agent (V) has been used beforehand than without the use of the pretreatment agent (V).

[0180] The improvement in washfastness can be quantified, for example, through colorimetric measurements (measurement of L, a, and b values) and calculation of the color difference. The smaller the color difference between washed and unwashed hair, the better the washfastness or color retention.

[0181] Examples

[0182] 1 . Formulations

[0183] The following formulations were prepared (all data in wt.% unless otherwise stated):

[0184] 2. Application to strands

[0185] The ready-to-use pretreatment agent (V) was prepared by mixing 2 parts by weight of carbamide peroxide gel (agent (1-1) or agent (1-2)) and 1 part by weight of persulfate bleaching powder (agent (2)). The thus prepared ready-to-use pretreatment agent (V) was applied to each strand of hair (Kerling 9 / 0). For this purpose, 4.0 g of pretreatment agent (V) per gram of hair was applied to the strands, massaged in, and left to work at room temperature for 30 minutes. The strands were then rinsed with water.

[0186] Immediately afterward, the dye (F) was applied to the hair strands. 0.4 g of dye was applied per 1 g of hair strand and left to work for 15 minutes at 30°C. The hair strands were then rinsed under running water for 1 minute. The strands were then dried in a warm air stream. For comparison, one strand was dyed with dye (F) without any pretreatment (V).

[0187] After drying, each strand was colorimetrically measured.

[0188] 3. Measurement of wash fastness

[0189] Following the treatment described in step 2, each colored strand underwent six manual hair washes. For each wash, the strand was moistened, then a commercially available shampoo (Schwarzkopf, Schauma 7 Kräuter) was massaged into the strand for 25 seconds (0.25 g of shampoo per gram of hair). The strand was then rinsed with lukewarm tap water for 30 seconds and dried. After six washes, the strands were colorimetrically measured again.

[0190] The dL value used to assess the color difference is calculated from the L*a*b* color values ​​measured on the respective strand as follows: dL =1 Lo- Li I

[0191] Lo = brightness of the colored strand

[0192] Li = brightness of the dyed and washed strand

[0193] (Difference given as absolute value function).

[0194] The larger the dL value, the greater the difference in brightness between the dyed hair and the dyed and washed hair and the stronger the color change (i.e. the worse the washfastness).

[0195] In Example 1, the strand of hair was treated only with the dye (F); this strand shows the worst washfastness after 6 hair washes.

[0196] The strand dyed in Example 2 was first treated with pretreatment agent (V), which was obtained by mixing agents (1-1) and (2). The strand dyed in Example 2 showed the greatest improvement in washfastness. The pretreatment agent used in Example 3 was obtained by mixing agents (1-2) and (2). The pretreatment agent used in Example 3 also shows an improvement in washfastness compared to Example 1.

[0197] The dE value can also be used to assess washfastness. This is calculated from the L*a*b* color values ​​measured on the respective strand as follows: dE = [ (Li - Lo) 2 + (ai - ao) 2 + (bi - bo) 2 ] 1 / 2

[0198] Lo, ao and bo = measurements of the dyed strand

[0199] Li, ai and bi = measurements of the dyed and washed strand

[0200] The larger the dE value, the greater the color difference between the colored hair and the colored and washed hair and the stronger the color change (i.e., the worse the washfastness).

[0201] In summary, the wash fastness of the dyeings obtained could be improved by the successive application of agents (V) and (F) according to the invention.

Claims

Patent claims 1. A method for dyeing keratinous fibers, especially human hair, comprising the following steps: - Application of a pretreatment agent (V) to the keratinous fibers, wherein the pretreatment agent (V-Ox) contains at least one oxidizing agent, and - Application of a dye (F) to the keratinous fibers, wherein the dye is in a cosmetic carrier (F-DZ) contains at least one direct dye.

2. Method according to claim 1, characterized in that the pretreatment agent (V) contains one or more oxidizing agents (V-Ox) from the group consisting of carbamide peroxide, potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate.

3. Method according to one of claims 1 to 2, characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent (V) - contains (V-Ox1) 1.0 to 30.0 wt.%, preferably 3.0 to 20.0 wt.%, further preferably 6.0 to 15.0 wt.% and most preferably 8.0 to 15.0 wt.% carbamid peroxide, and (V-Ox2) one or more peroxodisulfates from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate in a total amount of 1.0 to 40.0 wt.%, preferably 3.0 to 30 wt.%, more preferably 6.0 to 20.0 wt.% and most preferably 9.0 to 17.0 wt.%.

4. Method according to one of claims 1 to 3, characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent (V) - contains one or more solvents from the group consisting of glycerin, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, ethanol, isopropanol, dipropylene glycol, diethylene glycol monoethyl ether, phenoxyethanol, benzyl alcohol, poly-Ci-Ce alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate in a total amount of 3.0 to 80 wt.%, preferably 5.0 to 60.0 wt.%, further preferably 9.0 to 40.0 wt.% and most preferably 12.0 to 25.0 wt.%.

5. Method according to one of claims 1 to 4, characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent - comprises one or more ethylene glycols of formula (EG-V) in a total quantity of 1.0 to 80.0 containing wt.%, preferably from 1.5 to 60.0 wt.%, further preferably from 3.0 to 40.0 wt.% and most preferably from 4.5 to 10.0 wt.%, where x represents an integer from 1 to 10000, preferably an integer from 2 to 500, further preferably an integer from 3 to 100 and most preferably an integer from 5 to 30.

6. Method according to any one of claims 1 to 5, characterized in that the pretreatment agent (V) contains 5.0 to 70.0 wt.%, preferably 10.0 to 60.0 wt.%, more preferably 15.0 to 50.0 wt.% and most preferably 20.0 to 40.0 wt.% water, based on the total weight of the pretreatment agent (V).

7. Method according to any one of claims 1 to 6, characterized in that the dye (F) contains at least one direct dye (F-DZ) from the group consisting of cationic, anionic and / or non-ionic direct dyes, particularly preferably from the group consisting of cationic direct dyes.

8. Method according to any one of claims 1 to 7, characterized in that the dye (F) contains at least one cationic direct dye (F-DZ) selected from the group consisting of Basic Blue 7, Basic Blue 26, Basic Violet 2 and Basic Violet 14, Basic Yellow 57, Basic Red 76, Basic Blue 16, Basic Blue 347 (Cationic Blue 347 / Dystar), HC Blue No. 16, Basic Blue 99, Basic Brown 16, Basic Brown 17, Yellow 87, Basic Orange 31 and Basic Red 51 and / or their salts.

9. A method according to any one of claims 1 to 8, characterized in that the dye (F) contains at least one non-ionic dye (F-DZ) selected from the group consisting of HC Yellow 2, HC Yellow 4, HC Yellow 5, HC Yellow 6, HC Yellow 12, HC Orange 1, Disperse Orange 3, HC Red 1, HC Red 3, HC Red 10, HC Red 11, HC Red 13, HC Red BN, HC Blue 2, HC Blue 1, HC Blue 12, Disperse Blue 3, HC Violet 1, Disperse Violet 1, Disperse Violet 4, Disperse Black 9, 1,4-Diamino-2-nitrobenzene, 2-Amino-4-nitrophenol, 1,4-Bis-(2-hydroxyethyl)-amino-2-nitrobenzene, 3-Nitro-4-(2-hydroxyethyl)-aminophenol, 2-(2-hydroxyethyl)-amino-4,6-dinitrophenol, 4-[(2-hydroxyethyl)amino]-3-nitro-1-methylbenzene, 1-amino-4-(2-hydroxyethyl)-amino-5-chloro-2-nitrobenzene, 4-amino-3-nitrophenol, 1-(2'-Ureidoethyl)amino-4-nitrobenzene, 2-[(4-amino-2-nitrophenyl)amino]-benzoic acid, 6-nitro- 1,2,3,4-tetrahydroquinoxaline, 2-Hydroxy-1,4-naphthoquinone, picramic acid and their salts, 2-Amino-6-chloro-4-nitrophenol, 4-Ethylamino-3-nitrobenzoic acid and 2-Chloro-6-ethylamino-4-nitrophenol.

10. Method according to any one of claims 1 to 9, characterized in that the dye (F) contains at least one anionic direct dye (F-DZ) selected from the group consisting of bromophenol blue, tetrabromophenol blue, Acid Yellow 1, Yellow 10, Acid Yellow 23, Acid Yellow 36, Acid Orange 7, Acid Red 33, Acid Red 52, Acid Blue 7, Acid Green 50, Acid Violet 43, Acid Black 1 and Acid Black 52 and their salts.

11. Method according to any one of claims 1 to 10, characterized in that the dyeing agent (F) - based on the total weight of the dyeing agent (F) - contains one or more direct dyes (F-DZ) in a total amount of 0.0001 to 10.0 wt.%, preferably 0.1 to 5.0 wt.%, more preferably 0.2 to 2.5 wt.% and most preferably 0.25 to 1.5 wt.%.

12. Method according to any one of claims 1 to 11, characterized in that the pretreatment agent (V) is applied to the keratinous fibers before the dyeing agent (F) and that a rinsing step is performed between the application of the pretreatment agent (V) and the dyeing agent (F).

13. Method according to one of claims 1 to 12, characterized in that a period of at most 24 hours, preferably at most 12 hours, more preferably at most 6 hours and most preferably at most 3 hours lies between the application of the pretreatment agent (V) and the application of the dyeing agent (F).

14. A method according to any one of claims 1 to 13, comprising the following steps: (1) Providing a first agent containing carbamide peroxide (2) Providing a second agent containing one or more peroxodisulfates from the group consisting of potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate, (3) Mixing the first and the second agents to produce a ready-to-use pretreatment agent (V), (4) Applying the pretreatment agent (V) produced in step (3) to the keratinous fibers, (5) The pretreatment agent (V) applied in step (4) is applied to the keratinous fibers for a period of 2 to 45 minutes, preferably 2 to 30 minutes and particularly preferably 2 to 20 minutes, (6) Rinsing off the pretreatment agent (V), and (7) Applying the dye (F) to the keratin fibers.

15. The method of claim 14, comprising the (8) Applying the dye (F) applied in step (7) to the keratinous fibers for a period of 2 to 60 minutes, preferably 5 to 45 minutes, particularly preferably 10 to 30 minutes, and the (9) Rinsing out the dye.

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