DE102023203835A1 - Process for dyeing keratin fibers comprising the application of an oxidative pretreatment agent and a dye containing chitosan and pigment - Google Patents

Abstract

The present invention relates to 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 (V-1) contains at least one oxidizing agent, and- application of a dye (F) to the keratin fibers, wherein the dye contains in a cosmetic carrier (F-1) at least one chitosan and/or a chitosan derivative, and (F-2) at least one pigment.

Description

The subject of the present application is a cosmetic method for coloring keratin fibers, in particular human hair, which comprises the use of at least two different agents (V) and (F). Agent (V) is a pretreatment agent which contains at least one oxidizing agent in a cosmetic carrier. Coloring agent (F) contains at least one chitosan or a derivative thereof (F-1) and at least one pigment (F-2) in a cosmetic carrier.

Changing the shape and color of keratin material, especially human hair, is an important area of modern cosmetics. Depending on the coloring requirements, experts know of various coloring systems for changing hair color. Oxidation dyes are usually used for permanent, intensive coloring with good fastness properties and good gray coverage. Such dyes contain oxidation dye precursors, so-called developer components and coupler components, which form the actual dyes under the influence of oxidizing agents such as hydrogen peroxide. Oxidation dyes are characterized by very long-lasting coloring results.

When using direct dyes, the already fully formed dyes diffuse from the dye into the hair fiber. Compared to oxidative hair coloring, the colors obtained with direct dyes are less durable and wash out more quickly. Colors with direct dyes usually remain on the hair for a period of between 5 and 20 washes.

The use of color pigments is known for short-term color changes on the hair and/or skin. Color pigments are generally understood to be insoluble, color-giving substances. These are present undissolved in the form of small particles in the coloring formulation and are only deposited on the outside of the hair fibers and/or the surface of the skin. Therefore, they can usually be removed without residue by washing them a few times with detergents containing surfactants. Various products of this type are available on the market under the name hair mascara.

Coloring with pigments offers various significant advantages. Since the pigments only attach themselves to the keratin fibers, especially the hair fibers, unwanted coloring can be removed quickly and easily without leaving any residue, thus offering the user the opportunity to return to their original hair color immediately and without much effort. This coloring process is therefore particularly attractive for consumers who do not want to re-color their hair regularly.

In addition to these many advantages, the pigment-based coloring system still has some disadvantages, which are due to the low penetration depth of the pigments into the keratin material. Since the pigments do not diffuse into the keratin fiber, but are merely deposited in the form of a shell or film on the outside of the fiber, the washfastness of the colors produced with this system still needs to be improved. Various studies have attempted to bind the pigment(s) more permanently to the surface of the hair using film-forming materials, usually polymers.

For example, DE 19847883 A1 to create pigment-based colorings using colorants that contain at least one chitosan and one pigment. By combining the pigments with chitosan, the abrasion resistance of the colorings should be improved. The great advantage of chitosans as film-forming materials is that they are based on biopolymers and therefore have improved ecological compatibility and degradability. As many users are showing increasing interest in products with sustainable or renewable raw materials, the use of biopolymers is increasingly coming into focus. Nevertheless, the colorings obtained with pigment and chitosan still have disadvantages in terms of their washfastness. Achieving uniform coloring over the entire length of the hair cannot yet be described as optimal either, as the durability of the films on different sections of hair, particularly in the areas at the roots and at the tips, varies.

In WO 2021/190810 A1 describes dyes with pigments that are bound to the hair surface via films made of amino-functionalized silicone polymers. The washfastness of these dyes could be improved by an oxidative pretreatment.

However, further work on the WO 2021/190810 A1 It turns out that the oxidative pretreatment, which was carried out here with the combination of hydrogen peroxide and peroxodisulfates, also resulted in lightening and damage to the hair. This can be particularly disadvantageous if the user uses pigment-based dyes because he wants to avoid lightening and damaging the hair. In addition, the aminosilicones used there did not meet the requirements that an environmentally conscious user places on the ecological profile of a product.

The aim of the present application was therefore to find a pigment-based dyeing process that would enable intensive colors to be achieved with improved washfastness. The dyeing should be carried out with the aid of biopolymers, and the hair should be lightened and damaged as little as possible by the dyeing process. Ideally, the hair should not be damaged at all by the use of the dye. In addition, a uniform color result should be achieved over the entire length of the keratin fiber, regardless of the degree of damage to the fiber.

Surprisingly, it has now been found that the wash fastness of dyed keratin fibers could be massively improved if the dyeing was carried out with a pigment and a chitosan and the keratin fibers were pretreated with at least one oxidizing agent before application of the dye.

• - Anwendung eines Vorbehandlungsmittels (V) auf den keratinischen Fasern, wobei das Vorbehandlungsmittel (V-1) mindestens ein Oxidationsmittel enthält, und
• - Anwendung eines Färbemittels (F) auf den keratinischen Fasern, wobei das Färbemittel in einem kosmetischen Träger (F-1) mindestens ein Chitosan und/oder ein Chitosanderivat, und (F-2) mindestens ein Pigment enthält.

A first object of the present invention is a method for dyeing keratin fibers, in particular human hair, comprising the following steps:

• - applying a pretreatment agent (V) to the keratin fibers, wherein the pretreatment agent (V-1) contains at least one oxidizing agent, and
• - application of a colorant (F) to the keratin fibers, wherein the colorant contains in a cosmetic carrier (F-1) at least one chitosan and/or a chitosan derivative, and (F-2) at least one pigment.

The work leading to this invention has shown that particularly intensive and wash-fast color results can be achieved on hair if the hair is colored by successive application of the two agents (V) and (F). Even after several washes, no undesirable or unattractive shift in shade occurred. The evenness of the color result was also greatly improved in this way.

keratin fibers

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

dyeing agents

The term "coloring agent" is used in the context of this invention for the coloring of keratin fibers, particularly hair, caused by the use of pigments. In this coloring, the pigments are deposited as color-imparting compounds in a homogeneous, uniform and smooth film on the surface of the keratin material. The film is formed by the chitosan(s).

pretreatment agent (V)

Before applying the dye (F), the pretreatment agent (V) is applied to the keratin fibers, in particular the hair, in the process according to the invention. The pretreatment agent described below is the ready-to-use pretreatment agent which can be applied directly to the keratin fibers or hair.

Oxidizing agent (V-1) or (V-2) in the pretreatment agent (V)

Oxidizing agents are understood to be substances with an oxidizing effect. Oxidizing agents commonly used in cosmetics are, for example, hydrogen peroxide and/or at least one addition product thereof, in particular with inorganic or organic compounds, such as, for example, sodium perborate, sodium percarbonate, magnesium percarbonate, sodium percarbonate, polyvinylpyrrolidone·n H ₂ O ₂ (n is a positive integer greater than 0), urea peroxide and melamine peroxide.

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 to be particularly suitable.

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

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 CH ₆ N ₂ O ₃ and bears the CAS number 124-43-6.

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

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

Ammonium peroxodisulfate, which can alternatively also be called ammonium persulfate, is the persulfate with the molecular formula (NH ₄ ) ₂ S ₂ O ₈ .

Potassium peroxodisulfate, which can alternatively also be called potassium persulfate, is the persulfate with the molecular formula K ₂ S ₂ O ₈ .

Sodium peroxodisulfate, which can also be referred to as sodium persulfate, is the persulfate with the molecular formula Na ₂ S ₂ O ₈ .

In a particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains one or more oxidizing agents (V-1) from the group consisting of carbamide peroxide, potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate.

When carrying out the tests leading to this invention, it was found that a strong and effective improvement in wash fastness could be achieved in particular when a pretreatment agent (V) was used in the process according to the invention which contained a combination of different oxidizing agents. Particularly good results were obtained when using a pretreatment agent (V) containing the combination of carbamide peroxide (V-1) and at least one peroxodisulfate (V-2) from the group of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) at least one peroxodisulfate selected from the group consisting of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) Ammonium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) Potassium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) Sodium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) 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-1) carbamide peroxide and
(V-2) Ammonium peroxodisulfate and sodium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) Potassium peroxodisulfate and sodium peroxodisulfate.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the pretreatment agent (V) contains (V-1) carbamide peroxide and
(V-2) Ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate.

According to the invention, the oxidative cosmetic pretreatment agent can additionally contain at least one catalyst as an optional component, which activates the oxidation of the substrate, such as the melanin in the keratin material. Such catalysts are, for example, metal ions, iodides, quinones or certain enzymes.

Suitable metal ions are, for example, 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⁺ are particularly suitable. 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.

• - Pyranose-Oxidase und z.B. D-Glucose oder Galactose,
• - Glucose-Oxidase und D-Glucose,
• - Glycerin-Oxidase und Glycerin,
• - Pyruvat-Oxidase und Benztraubensäure oder deren Salze,
• - Alkohol-Oxidase und Alkohol (MeOH, EtOH),
• - Lactat-Oxidase und Milchsäure und deren Salze,
• - Tyrosinase-Oxidase und Tyrosin,
• - Uricase und Harnsäure oder deren Salze,
• - Cholinoxidase und Cholin,
• - Aminosäure-Oxidase und Aminosäuren.

Suitable enzymes are, for example, peroxidases, which can significantly increase the effect of small amounts of hydrogen peroxide. Also suitable according to the invention are enzymes which generate small amounts of hydrogen peroxide in situ with the help of atmospheric oxygen and in this way 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.

• - Pyranose oxidase and e.g. D-glucose or galactose,
• - glucose oxidase and D-glucose,
• - Glycerol oxidase and glycerol,
• - pyruvate oxidase and benzoic acid or their salts,
• - alcohol oxidase and alcohol (MeOH, EtOH),
• - Lactate oxidase and lactic acid and their salts,
• - Tyrosinase oxidase and tyrosine,
• - Uricase and uric acid or their salts,
• - choline oxidase and choline,
• - Amino acid oxidase and amino acids.

By selecting the appropriate range of amounts of oxidizing agent(s) (V-1) (or (V-1) and (V-2)) in the pre-treatment agent (V), the extent of the influence that the pre-treatment agent (V) has on the wash fastness of the subsequently applied dye (F) can be controlled in a targeted manner. In this context, it has been found that the wash fastness is better the higher the amount of oxidizing agent used in the pre-treatment agent (V). On the other hand, however, the damage to the keratin material or the keratin fibers/hair also increases with increasing the amount of oxidizing agent used. In order to find the optimal balance between these two effects, it has proven particularly preferable to It has been found that the oxidizing agent(s) must be used in very specific quantity ranges in the pretreatment agent.

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 very particularly preferably 8.0 to 15.0 wt. % carbamide peroxide (V-1).

The pretreatment agent (V) according to the invention preferably contains - based on the total weight of the pretreatment agent - one or more persulfates (V-2) 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. %.

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
(V-1) 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
(V-2) one or more peroxodisulfates 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.%.

Cosmetic carrier of the pretreatment agent (V)

The oxidizing agent(s) (V-1) (or (V-1) and (V-2)) 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, paste or even a surfactant-containing foaming solution, such as a shampoo, foam aerosol, foam formulation or other preparations that are suitable for application to the hair. Water is the most common of all solvents in cosmetic products, so in principle water can also be used as the main ingredient as a cosmetic carrier.

However, in the work leading to this invention, it has been found 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).

For example, if the combination of carbamide peroxide (V-1) and peroxodisulfates (V-2) were used in pretreatment agents (V) with a very high water content, increased lightening and, associated with this, greater hair damage was observed. Although the washfastness of the pigment coloring could be improved using the process according to the invention, the hair was also damaged more severely. Surprisingly, hair damage could be massively reduced 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, but the surface or the cuticle is nevertheless modified so strongly that pigment-containing films can adhere there better.

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-C ₁ -C ₆ -alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate have proven to be particularly suitable.

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 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-C ₁ -C ₆ -alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate.

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 burdened 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 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-C ₁ -C ₆ -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 most preferably from 12.0 to 25.0 wt.%.

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 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-C ₁ -C ₆ 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.%.

Most preferably, the pretreatment agent (V) contains glycerin and 1,2-propanediol.

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

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. With an increase in the proportion of polyalkylene glycol(s) in the pretreatment agent (V), a reduction in hair damage and lightening of the pretreated keratin fibers was also observed. In this way, the subsequent application of the colorant (F) improved the washability and uniformity of the coloring without unduly damaging the keratin fibers and without lightening their original hair color. In this context, it is assumed that the dissolution of the carbamide peroxide or its reaction with the persulfates is also reduced by the polyalkylene glycols and that the oxidizing agents thus react with a time delay or only with the surface of the keratin fiber.

wobei
x für eine ganze Zahl von 1 bis 10000 , bevorzugt für eine ganze Zahl von 2 bis 500, weiter bevorzugt für eine ganze Zahl von 3 bis 100 und ganz besonders bevorzugt für eine ganze Zahl von 5 bis 30 steht.Polyalkylene glycols which are particularly suitable according to the invention are, for example, ethylene glycols of the formula (EG)

where
x stands for an integer from 1 to 10,000, preferably for an integer from 2 to 500, more preferably for an integer from 3 to 100 and most preferably for an integer from 5 to 30.

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

Depending on their chain length, polyethylene glycols are liquid or solid, water-soluble polymers. Polyethylene glycols with a molecular mass 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 masses above 3000 g/mol, PEGs are solid substances and are sold as flakes or powder.

In particular, the use of low molecular weight alkylene glycols (or polyethylene glycols) has proven to be particularly suitable for solving the problem of the invention. In the case of low molecular weight alkylene glycols (or polyethylene glycols) in the sense of the present invention, x1 is 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 very particularly preferably an integer from 6 to 15.

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

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

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

The polyalkylene glycol(s), in particular the polyethylene glycols of the formula (EG), are preferably used in the pretreatment agent (V) in amounts which 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 loaded with solvents. The pretreatment agent (V) preferably contains - based on the total weight of the pretreatment agent (V) - one or more ethylene glycols of the formula (EG) in a total amount of from 1.0 to 80% by weight, preferably from 1.5 to 60.0% by weight, more preferably from 3.0 to 40.0% by weight and very particularly preferably from 4.5 to 10.0% by weight.

wobei
x für eine ganze Zahl von 1 bis 10000 , bevorzugt für eine ganze Zahl von 2 bis 500, weiter bevorzugt für eine ganze Zahl von 3 bis 100 und ganz besonders bevorzugt für eine ganze Zahl von 5 bis 30 steht.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 ethylene glycols of the formula (EG) in a total amount of 1.0 to 80 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 stands for an integer from 1 to 10,000, preferably for an integer from 2 to 500, more preferably for an integer from 3 to 100 and most preferably for an integer from 5 to 30.

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).

• - ein oder mehrere Lösungsmittel aus der Gruppe aus Glycerin, 1,2-Propylenglycol, 1,3-Propylenglycol, 1,2-Butylenglycol, Ethanol, Isopropanol, Dipropylenglycol, Diethylenglycolmonoethylether, Phenoxyethanol, Benzylalkohol, Poly-C₁-C₆-Alkylenglycolen, Dimethylcarbonat, Diethylcarbonat, Ethylencarbonat, Propylencarbonat, Butylencarbonat und Glycerolcarbonat, und
• - ein oder mehrere Ethylenglycole der zuvor beschriebenen Formel (EG).

In a further particularly preferred embodiment, the pretreatment agent (V) according to the invention 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-C ₁ -C ₆ alkylene glycols, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate, and
• - one or more ethylene glycols of the formula described above (EG).

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 to be particularly preferred to set the water content in the pretreatment agent to a medium to low range. It is therefore particularly advantageous if 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.

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.

dye (F)

Following the application of the pretreatment agent (V), the colorant (F) is then applied to the keratin material in the process according to the invention. The colorant (F) contains at least one chitosan and/or a chitosan derivative (F-1) and (F-2) at least one pigment in a cosmetic carrier.

Cosmetic carrier of the colorant (F)

A suitable aqueous, alcoholic or aqueous-alcoholic carrier can be used as a cosmetic carrier for the colorant (F), for example. For the purpose of hair coloring, such carriers are, for example, creams, emulsions, gels, pastes or surfactant-containing foaming solutions, such as shampoos, foam aerosols, foam formulations or other preparations that are suitable for use on the hair. The cosmetic carrier for the colorant is particularly preferably a water-rich carrier, i.e. the colorant (F) preferably has a high water content. It has been found that the colorants (F) that are particularly suitable for use in the process according to the invention are those that contain - based on the total weight of the pretreatment agent (V) - 50.0 to 99.0% by weight, preferably 60.0 to 99.0% by weight, more preferably 70.0 to 99.0% by weight and very particularly preferably 80.0 to 99.0% by weight of water.

In one embodiment, a process according to the invention is characterized in that the colorant (F) - based on the total weight of the colorant (F) - contains 50.0 to 99.0 wt.%, preferably 60.0 to 99.0 wt.%, more preferably 70.0 to 99.0 wt.% and most preferably 80.0 to 99.0 wt.% of water.

Chitosans (F-1) in the dye (F)

Chitosan, which can also be referred to as poliglusam or poly-D-glucosamine or polyglucosamine, is a naturally occurring biopolymer derived from chitin, which is composed of β-1,4-glycosidically linked N-acetylglucosamine residues (more precisely 2-acetamido-2-deoxy-β-D-glucopyranose residues), and is thus, like chitin, a polyaminosaccharide. To produce chitosan, chitin is deacetylated so that the molecule ultimately consists of only about 2000 linearly linked 2-amino-2-deoxy-β-D-glucopyranose or glucosamine monomers. Chitosan has the CAS number 9012-76-4.

Chitosan is preferably produced from the chitin contained in shellfish or crustaceans. Chitosan is obtained technically from chitin by deacetylation. This can be done, for example, using (hot) sodium hydroxide solution or enzymatically. Both processes are used technically, but in terms of quantity, the alkaline procedure is clearly the most common. The degree of the resulting deacetylation can vary considerably: deacetylation can be complete or partial, which can result in a distribution of strongly deacetylated areas next to slightly deacetylated areas or a homogeneous deacetylation distribution. At the same time, this chemical intervention can reduce the chain length of the polymer (depolymerization). The molecular weight of chitosan can be distributed over a wide spectrum, for example from 20,000 to around 5 million g/mol.

Chitosan derivatives are compounds with a chitosan basic structure in which at least some of the existing functional groups have been chemically modified. Chitosan derivatives are also based on a poly-D-glucosamine or polyglucosamine structure.

For example, a chitosan with a molecular weight of 20,000 to 800,000 g/mol, preferably 50,000 to 600,000 g/mol, more preferably 80,000 to 450,000 g/mol and most preferably 100,000 to 300,000 g/mol is very suitable.

In a further very particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one chitosan and/or a chitosan derivative (F-1) with a molecular weight of 20,000 to 800,000 g/mol, preferably 50,000 to 600,000 g/mol, more preferably 80,000 to 450,000 g/mol and very particularly preferably 100,000 to 300,000 g/mol.

In a further very particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one chitosan (F-1) with a molecular weight of 20,000 to 800,000 g/mol, preferably 50,000 to 600,000 g/mol, more preferably 80,000 to 450,000 g/mol and very particularly preferably 100,000 to 300,000 g/mol.

A chitosan with a molecular weight of 100,000 to 300,000 g/mol can be purchased commercially, for example from Sigma Aldrich.

A chitosan with a lower molecular weight of 10,000 to 30,000 g/mol (or Dalton) can be purchased in pharmaceutical purity from the company BioLog Heppe (Kraeber), for example. The degree of deacetylation of this chitosan is 88 - 95%.

Chitosan in the form of its hydrochloride can be purchased as vegan chitosan from the company Sandream Impact. The hydrochloride of the chitosan is a chitosan derivative according to the invention.

Chitosan O27 is a suitable high molecular weight chitosan from Polymar, which has a molecular weight of 100,000 - 2,000,000 g/mol.

It has been found to be particularly advantageous if the colorant according to the invention contains the chitosans and/or chitosan derivatives (F-1) in certain quantity ranges. Particularly good results were obtained if the colorant - based on the total weight of the colorant - contained one or more chitosans and/or chitosan derivatives in a total amount of 0.1 to 10.0 wt.%, preferably 0.2 to 8.0 wt.%, more preferably 0.5 to 6.0 wt.% and most preferably 0.7 to 2.0 wt.%.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) - based on the total weight of the colorant - contains one or more chitosans and/or chitosan derivatives in a total amount of 0.1 to 10.0 wt. %, preferably 0.2 to 8.0 wt. %, more preferably 0.5 to 6.0 wt. %, and most preferably 0.7 to 2.0 wt. %.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) - based on the total weight of the colorant - contains one or more chitosans in a total amount of 0.1 to 10.0 wt. %, preferably 0.2 to 8.0 wt. %, more preferably 0.5 to 6.0 wt. %, and most preferably 0.7 to 2.0 wt. %.

Pigments (F-2) in the dye (F)

As a second essential component of the invention, the colorant (F) used in the process according to the invention contains at least one pigment.

Pigments in the sense of the present invention are understood to mean coloring compounds which have a solubility in water at 25 °C of less than 0.5 g/L, preferably less than 0.1 g/L, even more preferably less than 0.05 g/L. The water solubility can be determined, for example, using the method described below: 0.5 g of the pigment are weighed in a beaker. A stir bar is added. Then one liter of distilled water is added. This mixture is heated to 25 °C for one hour while stirring on a magnetic stirrer. If undissolved components of the pigment are still visible in the mixture after this period, the solubility of the pigment is below 0.5 g/L. If the pigment-water mixture dissolves due to the high If the intensity of the finely dispersed pigment, if present, cannot be assessed visually, the mixture is filtered. If a portion of undissolved pigment remains on the filter paper, the solubility of the pigment is below 0.5 g/L.

Suitable color pigments can be of inorganic and/or organic origin.

In a preferred embodiment, a colorant (F) according to the invention is characterized in that it contains at least one color-imparting compound (F-2) from the group of inorganic and/or organic pigments.

In a preferred embodiment, a colorant (F) according to the invention is characterized in that it contains at least one inorganic and/or organic pigment (F-2).

Preferred color pigments are selected from synthetic or natural inorganic pigments. Inorganic color pigments of natural origin can be made from chalk, ochre, umber, green earth, burnt terra di siena or graphite, for example. Black pigments such as iron oxide black, colored pigments such as ultramarine or iron oxide red as well as fluorescent or phosphorescent pigments can also be used as inorganic color pigments.

Particularly suitable are colored metal oxides, hydroxides and oxide hydrates, mixed phase pigments, sulfur-containing silicates, silicates, metal sulfides, complex metal cyanides, metal sulfates, chromates and/or molybdates. Particularly preferred color pigments are black iron oxide (CI 77499), yellow iron oxide (CI 77492), red and brown iron oxide (CI 77491), manganese violet (CI 77742), ultramarines (sodium aluminum sulfosilicates, CI 77007, Pigment Blue 29), chromium oxide hydrate (CI77289), iron blue (ferric ferrocyanide, CI77510) and/or carmine (cochineal).

Colored pearlescent pigments that are also particularly preferred according to the invention are colored pearlescent pigments. These are usually based on mica and/or mica and can be coated with one or more metal oxides. Mica is one of the layered silicates. The most important representatives of these silicates are muscovite, phlogopite, paragonite, biotite, lepidolite and margarite. To produce the pearlescent pigments in combination with metal oxides, the mica, predominantly muscovite or phlogopite, is coated with a metal oxide.

As an alternative to natural mica, synthetic mica coated with one or more metal oxides can also be used as a pearlescent pigment. Particularly preferred pearlescent pigments are based on natural or synthetic mica and are coated with one or more of the metal oxides mentioned above. The color of the respective pigments can be varied by varying the layer thickness of the metal oxide(s).

In a further preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least inorganic pigment (F-2), which is preferably selected from the group of colored metal oxides, metal hydroxides, metal oxide hydrates, silicates, metal sulfides, complex metal cyanides, metal sulfates, bronze pigments and/or from colored pigments based on mica or mica, which are coated with at least one metal oxide and/or one metal oxychloride.

In a further preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one pigment which is selected from mica-based pigments coated with one or more metal oxides from the group consisting of titanium dioxide (CI 77891), black iron oxide (CI 77499), yellow iron oxide (CI 77492), red and/or brown iron oxide (CI 77491, CI 77499), manganese violet (CI 77742), ultramarines (sodium aluminum sulfosilicates, CI 77007, Pigment Blue 29), chromium oxide hydrate (CI 77289), chromium oxide (CI 77288) and/or iron blue (ferric ferrocyanide, CI 77510).

Examples of particularly suitable colour pigments are commercially available under the trade names Rona®, Colorona®, Xirona®, Dichrona® and Timiron® from Merck, Ariabel® and Unipure® from Sensient, Prestige® from Eckart Cosmetic Colors and Sunshine® from Sunstar.

• Colorona Copper, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Passion Orange, Merck, Mica, CI 77491 (Iron Oxides), Alumina
• Colorona Patina Silver, Merck, MICA, CI 77499 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE) Colorona RY, Merck, CI 77891 (TITANIUM DIOXIDE), MICA, CI 75470 (CARMINE)
• Colorona Oriental Beige, Merck, MICA, CI 77891 (TITANIUM DIOXIDE), CI 77491 (IRON OXIDES) Colorona Dark Blue, Merck, MICA, TITANIUM DIOXIDE, FERRIC FERROCYANIDE
• Colorona Chameleon, Merck, CI 77491 (IRON OXIDES), MICA
• Colorona Aborigine Amber, Merck, MICA, CI 77499 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE)
• Colorona Blackstar Blue, Merck, CI 77499 (IRON OXIDES), MICA
• Colorona Patagonian Purple, Merck, MICA, CI 77491 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE), CI 77510 (FERRIC FERROCYANIDE)
• Colorona Red Brown, Merck, MICA, CI 77491 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE) Colorona Russet, Merck, CI 77491 (TITANIUM DIOXIDE), MICA, CI 77891 (IRON OXIDES) Colorona Imperial Red, Merck, MICA, TITANIUM DIOXIDE (CI 77891), D&C RED NO. 30 (CI 73360)
• Colorona Majestic Green, Merck, CI 77891 (TITANIUM DIOXIDE), MICA, CI 77288 (CHROMIUM OXIDE GREENS)
• Colorona Light Blue, Merck, MICA, TITANIUM DIOXIDE (CI 77891), FERRIC FERROCYANIDE (CI 77510)
• Colorona Red Gold, Merck, MICA, CI 77891 (TITANIUM DIOXIDE), CI 77491 (IRON OXIDES) Colorona Gold Plus MP 25, Merck, MICA, TITANIUM DIOXIDE (CI 77891), IRON OXIDES (CI 77491)
• Colorona Carmine Red, Merck, MICA, TITANIUM DIOXIDE, CARMINE
• Colorona Blackstar Green, Merck, MICA, CI 77499 (IRON OXIDES)
• Colorona Bordeaux, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Bronze, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Bronze Fine, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Fine Gold MP 20, Merck, MICA, CI 77891 (TITANIUM DIOXIDE), CI 77491 (IRON OXIDES)
• Colorona Sienna Fine, Merck, CI 77491 (IRON OXIDES), MICA
• Colorona Sienna, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Precious Gold, Merck, Mica, CI 77891 (Titanium dioxide), Silica, CI 77491 (Iron oxides), Tin oxide
• Colorona Sun Gold Sparkle MP 29, Merck, MICA, TITANIUM DIOXIDE, IRON OXIDES, MICA, CI 77891, CI 77491 (EU)
• Colorona Mica Black, Merck, CI 77499 (Iron oxides), Mica, CI 77891 (Titanium dioxide)
• Colorona Bright Gold, Merck, Mica, CI 77891 (Titanium dioxide), CI 77491 (Iron oxides)
• Colorona Blackstar Gold, Merck, MICA, CI 77499 (IRON OXIDES)

Particularly preferred color pigments with the trade name Colorona® are, for example:

• Colorona Copper, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Passion Orange, Merck, Mica, CI 77491 (Iron Oxides), Alumina
• Colorona Patina Silver, Merck, MICA, CI 77499 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE) Colorona RY, Merck, CI 77891 (TITANIUM DIOXIDE), MICA, CI 75470 (CARMINE)
• Colorona Oriental Beige, Merck, MICA, CI 77891 (TITANIUM DIOXIDE), CI 77491 (IRON OXIDES) Colorona Dark Blue, Merck, MICA, TITANIUM DIOXIDE, FERRIC FERROCYANIDE
• Colorona Chameleon, Merck, CI 77491 (IRON OXIDES), MICA
• Colorona Aboriginal Amber, Merck, MICA, CI 77499 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE)
• Colorona Blackstar Blue, Merck, CI 77499 (IRON OXIDES), MICA
• Colorona Patagonian Purple, Merck, MICA, CI 77491 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE), CI 77510 (FERRIC FERROCYANIDE)
• Colorona Red Brown, Merck, MICA, CI 77491 (IRON OXIDES), CI 77891 (TITANIUM DIOXIDE) Colorona Russet, Merck, CI 77491 (TITANIUM DIOXIDE), MICA, CI 77891 (IRON OXIDES) Colorona Imperial Red, Merck, MICA, TITANIUM DIOXIDE (CI 77891), D&C RED NO. 30 (CI 73360)
• Colorona Majestic Green, Merck, CI 77891 (TITANIUM DIOXIDE), MICA, CI 77288 (CHROMIUM OXIDE GREENS)
• Colorona Light Blue, Merck, MICA, TITANIUM DIOXIDE (CI 77891), FERRIC FERROCYANIDE (CI 77510)
• Colorona Red Gold, Merck, MICA, CI 77891 (TITANIUM DIOXIDE), CI 77491 (IRON OXIDES) Colorona Gold Plus MP 25, Merck, MICA, TITANIUM DIOXIDE (CI 77891), IRON OXIDES (CI 77491)
• Colorona Carmine Red, Merck, MICA, TITANIUM DIOXIDE, CARMINE
• Colorona Blackstar Green, Merck, MICA, CI 77499 (IRON OXIDES)
• Colorona Bordeaux, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Bronze, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Bronze Fine, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Fine Gold MP 20, Merck, MICA, CI 77891 (TITANIUM DIOXIDE), CI 77491 (IRON OXIDES)
• Colorona Sienna Fine, Merck, CI 77491 (IRON OXIDES), MICA
• Colorona Sienna, Merck, MICA, CI 77491 (IRON OXIDES)
• Colorona Precious Gold, Merck, Mica, CI 77891 (Titanium dioxide), Silica, CI 77491 (Iron oxides), Tin oxide
• Colorona Sun Gold Sparkle MP 29, Merck, MICA, TITANIUM DIOXIDE, IRON OXIDES, MICA, CI 77891, CI 77491 (EU)
• Colorona Mica Black, Merck, CI 77499 (Iron oxides), Mica, CI 77891 (Titanium dioxide)
• Colorona Bright Gold, Merck, Mica, CI 77891 (Titanium dioxide), CI 77491 (Iron oxides)
• Colorona Blackstar Gold, Merck, MICA, CI 77499 (IRON OXIDES)

• Xirona Golden Sky, Merck, Silica, CI 77891 (Titanium Dioxide), Tin Oxide
• Xirona Caribbean Blue, Merck, Mica, CI 77891 (Titanium Dioxide), Silica, Tin Oxide
• Xirona Kiwi Rose, Merck, Silica, CI 77891 (Titanium Dioxide), Tin Oxide
• Xirona Magic Mauve, Merck, Silica, CI 77891 (Titanium Dioxide), Tin Oxide.

Other particularly preferred color pigments with the trade name Xirona® include:

• Xirona Golden Sky, Merck, Silica, CI 77891 (Titanium Dioxide), Tin Oxide
• Xirona Caribbean Blue, Merck, Mica, CI 77891 (Titanium Dioxide), Silica, Tin Oxide
• Xirona Kiwi Rose, Merck, Silica, CI 77891 (Titanium Dioxide), Tin Oxide
• Xirona Magic Mauve, Merck, Silica, CI 77891 (Titanium Dioxide), Tin Oxide.

• Unipure Red LC 381 EM, Sensient CI 77491 (Iron Oxides), Silica
• Unipure Black LC 989 EM, Sensient, CI 77499 (Iron Oxides), Silica
• Unipure Yellow LC 182 EM, Sensient, CI 77492 (Iron Oxides), Silica

In addition, particularly preferred color pigments with the trade name Unipure® are, for example:

• Unipure Red LC 381 EM, Sensient CI 77491 (Iron Oxides), Silica
• Unipure Black LC 989 EM, Sensient, CI 77499 (Iron Oxides), Silica
• Unipure Yellow LC 182 EM, Sensient, CI 77492 (Iron Oxides), Silica

In a further embodiment, the pretreatment agent (V) according to the invention can also contain one or more organic pigments

The organic pigments according to the invention are correspondingly insoluble, organic dyes or colored lakes which can be selected, for example, from the group of nitroso, nitro, azo, xanthene, anthraquinone, isoindolinone, isoindoline, quinacridone, perinone, perylene, diketopyrrolopyorrole, indigo, thioindido, dioxazine and/or triarylmethane compounds.

Particularly suitable organic pigments are, for example, carmine, quinacridone, phthalocyanine, sorghum, blue pigments with the color index numbers CI 42090, CI 69800, CI 69825, CI 73000, CI 74100, CI 74160, yellow pigments with the color index numbers CI 11680, CI 11710, CI 15985, CI 19140, CI 20040, CI 21100, CI 21108, CI 47000, CI 47005, green pigments with the color index numbers CI 61565, CI 61570, CI 74260, orange pigments with the color index numbers CI 11725, CI 15510, CI 45370, CI 71105, red pigments with the Color index numbers CI 12085, CI 12120, CI 12370, CI 12420, CI 12490, CI 14700, CI 15525, CI 15580, CI 15620, CI 15630, CI 15800, CI 15850, CI 15865, CI 15880, CI 1720 0, CI 26100, CI 45380, CI 45410, CI 58000, CI 73360, CI 73915 and/or CI 75470.

In a further particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) contains at least one organic pigment (F-2), which is preferably selected from the group consisting of carmine, quinacridone, phthalocyanine, sorghum, blue pigments with the color index numbers CI 42090, CI 69800, CI 69825, CI 73000, CI 74100, CI 74160, yellow pigments with the color index numbers CI 11680, CI 11710, CI 15985, CI 19140, CI 20040, CI 21100, CI 21108, CI 47000, CI 47005, green pigments with the color index numbers CI 61565, CI 61570, CI 74260, orange pigments with the color index numbers CI 11725, CI 15510, CI 45370, CI 71105, red pigments with the color index numbers CI 12085, CI 12120, CI 12370, CI 12420, CI 12490, CI 14700, CI 15525, CI 15580, CI 15620, CI 15630, CI. 15800, CI 15850, CI 15865, CI 15880, CI 17200, CI 26100, CI 45380, CI 45410, CI 58000, CI 73360, CI 73915 and/or CI 75470.

The organic pigment can also be a colored lake. For the purposes of the invention, the term colored lake refers to particles which comprise a layer of absorbed dyes, whereby the unit of particle and dye is insoluble under the above-mentioned conditions. The particles can be, for example, inorganic substrates which can be aluminum, silica, calcium borosilicate, calcium aluminum borosilicate or even aluminum.

Alizarin varnish, for example, can be used as a colored varnish.

Due to their excellent light and temperature resistance, the use of the aforementioned pigments in the colorant (F) of the process according to the invention is very particularly preferred. It is also preferred if the pigments used have a certain particle size. It is therefore advantageous according to the invention if the at least one pigment has an average particle size D ₅₀ of 1.0 to 50 µm, preferably from 5.0 to 45 µm, preferably from 10 to 40 µm, in particular from 14 to 30 µm. The average particle size D ₅₀ can be determined, for example, using dynamic light scattering (DLS).

Pigments with a specific shape can also be used to color the keratin fibers. For example, a pigment based on a lamellar and/or lenticular substrate plate can be used. Coloring based on a substrate plate that contains a vacuum-metallized pigment is also possible.

In a further preferred embodiment, an agent according to the invention is characterized in that it contains at least one pigment (a2) which is selected from the group of pigments based on a lamellar substrate platelet, pigments based on a lenticular substrate platelet and vacuum-metallized pigments.

The substrate platelets of this type have an average thickness of at most 50 nm, preferably less than 30 nm, particularly preferably at most 25 nm, for example at most 20 nm. The average thickness of the substrate platelets is at least 1 nm, preferably at least 2.5 nm, particularly preferably at least 5 nm, for example at least 10 nm. Preferred ranges for the thickness of the substrate platelets are 2.5 to 50 nm, 5 to 50 nm, 10 to 50 nm; 2.5 to 30 nm, 5 to 30 nm, 10 to 30 nm; 2.5 to 25 nm, 5 to 25 nm, 10 to 25 nm, 2.5 to 20 nm, 5 to 20 nm and 10 to 20 nm. Each substrate platelet preferably has as uniform a thickness as possible. Due to the low thickness of the substrate platelets, the pigment has a particularly high hiding power.

The substrate platelets are preferably monolithic in structure. Monolithic in this context means consisting of a single, closed unit without breaks, layers or inclusions, although structural changes can occur within the substrate platelets. The substrate platelets are preferably homogeneous in structure, i.e. no concentration gradient occurs within the platelets. In particular, the substrate platelets are not layered and do not have any particles or particles distributed within them.

The size of the substrate plate can be tailored to the respective application, in particular the desired effect on the keratin material. As a rule, the substrate platelets have an average largest diameter of about 2 to 200 µm, in particular about 5 to 100 µm.

In a preferred embodiment, the aspect ratio, expressed as the ratio of the average size to the average thickness, is at least 80, preferably at least 200, more preferably at least 500, particularly preferably more than 750. The average size of the uncoated substrate platelets is understood to be the d50 value of the uncoated substrate platelets. Unless otherwise stated, the d50 value was determined using a Sympatec Helos device with Quixel wet dispersion. To prepare the sample, the sample to be examined was predispersed in isopropanol for a period of 3 minutes.

The substrate platelets can be made of any material that can be formed into platelets.

They can be of natural origin, but can also be synthetically produced. Materials from which the substrate platelets can be constructed include metals and metal alloys, metal oxides, preferably aluminum oxide, inorganic compounds and minerals such as mica and (semi)precious stones, as well as plastics. The substrate platelets are preferably constructed from metal (alloys).

Any metal suitable for metallic luster pigments can be considered as a metal. Such metals include iron and steel, as well as all air- and water-resistant (semi)metals such as platinum, zinc, chromium, molybdenum and silicon, as well as their alloys such as aluminum bronze and brass. Preferred metals are aluminum, copper, silver and gold. Preferred substrate plates are aluminum plates and brass plates, with aluminum substrate plates being particularly preferred.

Lamellar substrate platelets are characterized by an irregularly structured edge and are also called “cornflakes” due to their appearance.

Due to their irregular structure, pigments based on lamellar substrate platelets generate a high proportion of scattered light. In addition, the pigments based on lamellar substrate platelets do not completely cover the existing color of a keratin material and effects analogous to natural graying can be achieved, for example.

Lenticular (= lens-shaped) substrate platelets have an essentially regular round edge and are also called “silver dollars” due to their appearance. Due to their regular structure, the proportion of reflected light predominates in pigments based on lenticular substrate platelets.

Vacuum metallized pigments (VMP) can be obtained, for example, by releasing metals, metal alloys or metal oxides from appropriately coated films. They are characterized by a particularly low thickness of the substrate platelets in the range of 5 to 50 nm and by a particularly smooth surface with increased reflectivity. Substrate platelets which comprise a pigment metallized in a vacuum are also referred to as VMP substrate platelets. VMP substrate platelets made of aluminum can be obtained, for example, by releasing aluminum from metallized foils.

The substrate plates made of metal or metal alloy can be passivated, for example by anodizing (oxide layer) or chromating.

Uncoated lamellar, lenticular and/or VPM substrate plates, especially those made of metal or metal alloy, reflect the incident light to a high degree and produce a light-dark flop. These have proven to be particularly preferred for use in the colorant.

Suitable pigments based on a lamellar substrate platelet include, for example, the pigments of the VISIONAIRE series from Eckart.

Pigments based on a lenticular substrate plate are available, for example, under the name Alegrace® Gorgeous from Schlenk Metallic Pigments GmbH.

Pigments based on a substrate platelet, which comprises a vacuum metallized pigment, are available, for example, under the name Alegrace® Marvelous or Alegrace® Aurous from Schlenk Metallic Pigments GmbH.

The pigment(s) (F-2) represent(s) the second essential component of the colorant (F) according to the invention and are preferably used in the composition in certain quantity ranges. Particularly good results were obtained when the colorant - based on the total weight of the colorant - contained one or more pigments (F-2) in a total amount of 0.01 to 10.0% by weight, preferably 0.1 to 5.0% by weight, more preferably 0.2 to 2.5% by weight and most preferably 0.25 to 1.5% by weight.

In a further very particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) - based on the total weight of the colorant - contains one or more pigments (F-2) in a total amount of 0.01 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. %.

Direct dyes in the dye (F)

In principle, the colorants (F) used in the process according to the invention can also contain one or more direct dyes as optional components. Direct dyes are dyes that are absorbed directly onto the hair and do not require an oxidative process to form the color. Direct dyes are usually nitrophenylenediamines, nitroaminophenols, azo dyes, anthraquinones, triarylmethane dyes or indophenols.

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

The main advantage of the method according to the invention is that the colors that can be achieved with the pigment-based colorant (F) are, on the one hand, very wash-stable, but on the other hand also have a very high shade stability. This means that the fading of the color, if it occurs to a reduced extent after several washes of the keratin material, takes place while maintaining the color shade without any visible color shift. This shade stability can be observed even when the colorant (F) contains a mixture of pigments (F-2) of different colors.

Without being bound to this theory, it is assumed in this context that the reason for the high stability of the color nuance is that all pigments are deposited in the form of a film on the surface of the keratin material. In contrast to direct dyes, the pigments cannot diffuse into the keratin material, and also in contrast to direct dyes, the size or structure of a pigment cannot influence its depth of penetration into the keratin material.

If a mixture of direct dyes of different colors is applied to the keratin material, these different dyes are usually based on different chromophoric structures and molecules of different sizes. Due to their structural differences, these different dyes can diffuse into the keratin material to different depths and are washed out of the keratin material to different degrees during washing. Particularly with dyes in natural tones, which are created, for example, by using a mixture of a yellow, a red and a blue direct dye, a color shift from brown to yellowish, reddish or bluish can be observed over the course of several washes or shampooings.

The colors produced using the method according to the invention are based on a pigment-silicone film that is located on the surface of the keratin material. Washing tests have now shown that repeated washings lead to a slight reduction in color intensity, but that there is no shift in the color tone. The dissolution of different colored pigments from the film during hair washing is therefore much more even.

The fact that this color shift does not occur when using the process according to the invention is a significant advantage over a dyeing system based on direct dyes. For this reason, it is particularly preferred if the colorant (F) does not contain any direct dyes or contains them only in very small amounts.

In a further, very particularly preferred embodiment, a process according to the invention is characterized in that the total amount of direct dyes contained in the colorant (F) - based on the total weight of the colorant (F) - is below 0.1% by weight, preferably below 0.05% by weight, more preferably below 0.01% by weight and very particularly preferably below 0.001% by weight.

In other words, in a further very particularly preferred embodiment, a process according to the invention is characterized in that the total amount of the direct dyes contained in the colorant (F) - based on the total weight of the colorant (F) - is below 0.1% by weight, preferably below 0.05% by weight, more preferably below 0.01% by weight and very particularly preferably below 0.001% by weight, wherein the direct dyes are characterized in that they have a solubility in water (760 mmHg) at 25 °C of more than 0.5 g/L.

In a further, very particularly preferred embodiment, a process according to the invention is characterized in that the colorant (F) is free from direct dyes.

Direct dyes can be divided into anionic, cationic and non-ionic direct dyes.

Examples of cationic direct dyes include Basic Blue 7, Basic Blue 26, HC Blue 16, 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, Basic Yellow 57, Basic Yellow 87, Basic Orange 31, Basic Red 51 Basic Red 76.

Examples of non-ionic direct dyes include non-ionic nitro and quinone dyes and neutral azo dyes. Examples of non-ionic direct dyes are the compounds known under the international names or trade names 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, as well as 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.

Anionic direct dyes are also referred to as acid dyes. Acid dyes are direct dyes that have at least one carboxylic acid group (-COOH) and/or one sulfonic acid group (-SO ₃ H). Depending on the pH value, the protonated forms (-COOH, -SO ₃ H) of the carboxylic acid or sulfonic acid groups are in equilibrium with their deprotonated forms (-COO ^- , -SO ₃ ^- ). As the pH value decreases, the proportion of protonated forms increases. If direct dyes are used in the form of their salts, the carboxylic acid groups or sulfonic acid groups are in deprotonated form and are neutralized with corresponding stoichiometric equivalents of cations to maintain electroneutrality. Acid dyes according to the invention can also be used in the form of their sodium salts and/or their potassium salts.

The acid dyes in the sense of the present invention have a solubility in water (760 mmHg) at 25 °C of more than 0.5 g/L and are therefore not to be regarded as pigments. The acid dyes in the sense of the present invention preferably have a solubility in water (760 mmHg) at 25 °C of more than 1.0 g/L.

The alkaline earth salts (such as calcium salts and magnesium salts) or aluminum salts of acid dyes often have a poorer solubility than the corresponding alkali salts. If the solubility of these salts is below 0.5 g/L (25 °C, 760 mmHg), they do not fall under the definition of a direct dye.

An essential feature of acid dyes is their ability to form anionic charges, whereby the carboxylic acid or sulfonic acid groups responsible for this are usually linked to various chromophoric systems. Suitable chromophoric systems can be found, for example, in the structures of nitrophenylenediamines, nitroaminophenols, azo dyes, anthraquinone dyes, triarylmethane dyes, xanthene dyes, rhodamine dyes, oxazine dyes and/or indophenol dyes.

Examples of acid dyes that can be mentioned are: Acid Yellow 1 (D&C Yellow 7, Citronin A, Ext. D&C Yellow No. 7, Japan Yellow 403, CI 10316, COLIPA n° B001), Acid Yellow 3 (COLIPA n°: C 54, D&C Yellow N° 10, Quinoline Yellow, E104, Food Yellow 13), Acid Yellow 9 (CI 13015), Acid Yellow 17 (CI 18965), Acid Yellow 23 (COLIPA n° C 29, Covacap Jaune W 1100 (LCW ), Sicovit Tartrazine 85 E 102 (BASF), Tartrazine, Food Yellow 4, Japan Yellow 4, FD&C Yellow No. 5), Acid Yellow 36 (CI 13065), Acid Yellow 121 (CI 18690), Acid Orange 6 (CI 14270), Acid Orange 7 (2-Naphthol orange, Orange II, CI 15510, D&C Orange 4, COLIPA n° C015), Acid Orange 10 (C.I. 16230; Orange G sodium salt), Acid Orange 11 (CI 45370), Acid Orange 15 (CI 50120), Acid Orange 20 (CI 14600), Acid Orange 24 (BROWN 1;CI20170;KATSU201;nosodium salt;Brown No.201;RESORCIN BROWN;ACID ORANGE 24;Japan Brown 201;D & C Brown No.1), Acid Red 14 (C.I.14720), Acid Red 18 (E124, Red 18; CI 16255), Acid Red 27 (E 123, CI 16185, C-Red 46, Real Red D, FD&C Red No.2, Food Red 9, Naphthol Red S), Acid Red 33 (Red 33, Fuchsia Red, D&C Red 33, CI 17200), Acid Red 35 (CI C.I.18065) , Acid Red 51 (CI 45430, Pyrosin B, Tetraiodofluorescein, Eosin J, lodeosin), Acid Red 52 (CI 45100, Food Red 106, Solar Rhodamine B, Acid Rhodamine B, Red n° 106 Pontacyl Brilliant Pink), Acid Red 73 (CI CI 27290), Acid Red 87 (Eosin, CI 45380), Acid Red 92 (COLIPA n° C53, CI 45410), Acid Red 95 (CI 45425, Erythtosine,Simacid Erythrosine Y), Acid Red 184 (CI 15685), Acid Red 195, Acid Violet 43 (Jarocol Violet 43, Ext. D&C Violet n° 2, C.I. 60730, COLIPA n° C063), Acid Violet 49 (CI 42640), Acid Violet 50 (CI 50325), Acid Blue 1 (Patent Blue, CI 42045), Acid Blue 3 (Patent Blue V, CI 42051), Acid Blue 7 (CI 42080), Acid Blue 104 (CI 42735), Acid Blue 9 (E 133, Patent Blue AE, Amido Blue AE, Erioglaucine A, CI 42090, C.I. Food Blue 2), Acid Blue 62 (CI 62045), Acid Blue 74 ( E 132, CI 73015), Acid Blue 80 (CI 61585), Acid Green 3 (CI 42085, Foodgreen1), Acid Green 5 (CI 42095), Acid Green 9 (C.I.42100), Acid Green 22 (C.I.42170), Acid Green 25 (CI 61570, Japan Green 201, D&C Green No. 5), Acid Green 50 (brilliant acid green BS, C.I. 44090, Acid Brilliant Green BS, E 142), Acid Black 1 (Black n° 401, Naphthalene Black 10B, Amido Black 10B, CI 20 470, COLIPA n° B15), Acid Black 52 (CI 15711), Food Yellow 8 (CI 14270), Food Blue 5, D&C Yellow 8 , D&C Green 5, D&C Orange 10, D&C Orange 11, D&C Red 21, D&C Red 27, D&C Red 33, D&C Violet 2 and/or D&C Brown 1st

The water solubility of the anionic direct dyes can be determined in the following way, for example. 0.1 g of the anionic direct dye is placed in a beaker. A stir bar is added. 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 there are still undissolved residues, the amount of water is increased - for example in steps of 10 ml. Water is added until the amount of dye used has completely dissolved. If the dye-water mixture dissolves due to the high intensity If the solubility of the dye cannot be assessed visually, the mixture is filtered. If a portion of undissolved dye remains on the filter paper, the solubility test is repeated with 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.

Acid Yellow 1 is called 8-hydroxy-5,7-dinitro-2-naphthalenesulfonic acid disodium salt and has a solubility in water of at least 40 g/L (25°C).

Acid Yellow 3 is a mixture of the sodium salts of mono- and disulfonic acids of 2-(2-quinolyl)-1H-indene-1,3(2H)-dione and has a water solubility of 20 g/L (25 °C).

Acid Yellow 9 is the disodium salt of 8-hydroxy-5,7-dinitro-2-naphthalenesulfonic acid, its water solubility is above 40 g/L (25 °C).

Acid Yellow 23 is the trisodium salt of 4,5-dihydro-5-oxo-1-(4-sulfophenyl)-4-((4-sulfophenyl)azo)-1H-pyrazol-3-carboxylic acid and is readily soluble in water at 25 °C.

Acid Orange 7 is the sodium salt of 4-[(2-hydroxy-1-naphthyl)azo]benzenesulfonate. Its water solubility is more than 7 g/L (25 °C).

Acid Red 18 is the trisodium salt of 7-hydroxy-8-[(E)-(4-sulfonato-1-naphthyl)-diazenyl)]-1,3-naphthalenedisulfonate and has a very high water solubility of more than 20 wt.%. Acid Red 33 is the disodium salt of 5-amino-4-hydroxy-3-(phenylazo)-naphthalene-2,7-disulfonate and its water solubility is 2.5 g/L (25 °C).

Acid Red 92 is the disodium salt of 3,4,5,6-tetrachloro-2-(1,4,5,8-tetrabromo-6-hydroxy-3-oxoxanthen-9-yl)benzoic acid, whose water solubility is stated to be greater than 10 g/L (25 °C).

Acid Blue 9 is the disodium salt of 2-({4-[N-ethyl(3-sulfonatobenzyl]amino]phenyl}{4-[(N-ethyl(3-sulfonatobenzyl)imino]-2,5-cyclohexadien-1-ylidene}methyl)-benzenesulfonate and has a water solubility of more than 20 wt.% (25 °C).

other optional ingredients in the agents (V) and/or (F)

In addition to the components essential to the invention already described, the pretreatment agent (V) and/or the colorant (F) can also contain further optional ingredients.

The products can also contain other active ingredients, auxiliary substances and additives, such as solvents, fatty components such as C ₈ -C ₃₀ fatty alcohols, C ₈ -C ₃₀ fatty acid triglycerides, C ₈ -C ₃₀ fatty acid monoglycerides, C ₈ -C ₃₀ fatty acid diglycerides and/or hydrocarbons; 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 glucose, galactose, fructose, fructose and lactose; dyes for coloring the product; 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, where appropriate, anionically or cationically modified derivatives; vegetable oils; sunscreens and UV blockers; active ingredients such as panthenol, pantothenic acid, pantolactone, allantoin, pyrrolidinonecarboxylic 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 glycerine, 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; and propellants such as propane-butane mixtures, N ₂ O, dimethyl ether, CO ₂ and air.

The selection of these additional substances will be made by the specialist according to the desired properties of the product. Regarding further optional components and the amounts of these components used, For the additional active ingredients and excipients, reference is expressly made to the relevant manuals known to the person skilled in the art. The additional active ingredients and excipients are preferably used in the preparations according to the invention in amounts of 0.0001 to 25% by weight, in particular 0.0005 to 15% by weight, based on the total weight of the respective agent.

pH value of pretreatment agent (V) and/or dye (F)

The pH values of the agents (V) and (F) according to the invention can be adjusted to a slightly acidic to alkaline pH value.

In one embodiment, the pretreatment agent (V) has a pH value of 6.0 to 12.0, preferably from 7.0 to 11.5, more preferably from 7.5 to 11.0 and very particularly preferably from 9.0 to 11.0. If pretreatment agents (V) with these pH values were used in the process according to the invention, dyeings with particularly good fastness properties could be achieved.

In a further embodiment, a process according to the invention is characterized in that the pretreatment agent (V) has a pH of 6.0 to 12.0, preferably 7.0 to 11.5, more preferably 7.5 to 11.0 and most preferably 9.0 to 11.0.

The pH values of the colorant (F) according to the invention can be adjusted to a slightly acidic to alkaline pH value. The colorant (F) very particularly preferably has a pH value in the range from 3.0 to 10.0, preferably from 3.0 to 8.5, more preferably from 3.0 to 7.0 and very particularly preferably from 3.0 to 6.0.

Alkalizing agents and acidifying agents known to those skilled in the art can be used to set the respective desired pH values. The pH values within the meaning of the present invention are pH values that were measured at a temperature of 22°C.

The agents can contain, for example, ammonia, alkanolamines and/or basic amino acids as alkalizing agents.

The alkanolamines which can be used in the agent according to the invention are preferably selected from primary amines with a C ₂ -C ₆ alkyl parent structure which carries at least one hydroxyl group. Preferred alkanolamines are selected from the group consisting of 2-aminoethane-1-ol (monoethanolamine), 3-aminopropane-1-ol, 4-aminobutane-1-ol, 5-aminopentane-1-ol, 1-aminopropane-2-ol, 1-aminobutane-2-ol, 1-aminopentane-2-ol, 1-aminopentane-3-ol, 1-aminopentane-4-ol, 3-amino-2-methylpropane-1-ol, 1-amino-2-methylpropane-2-ol, 3-aminopropane-1,2-diol, 2-amino-2-methylpropane-1,3-diol.

Particularly preferred alkanolamines according to the invention are selected from 2-aminoethane-1-ol and/or 2-amino-2-methylpropane-1-ol. A particularly preferred embodiment is therefore characterized in that the agent according to the invention contains an alkanolamine selected from 2-aminoethane-1-ol and/or 2-amino-2-methylpropane-1-ol as an alkalizing agent.

An amino acid in the sense of the invention is an organic compound which contains in its structure at least one protonatable amino group and at least one -COOH- or -SO ₃ H- group. Preferred amino acids are aminocarboxylic acids, in particular α-(alpha)-aminocarboxylic acids and ω-aminocarboxylic acids, with α-aminocarboxylic acids being particularly preferred.

According to the invention, basic amino acids are understood to be amino acids which have an isoelectric point pl of greater than 7.0.

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

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

In addition, the agent can contain other alkalizing agents, in particular inorganic alkalizing agents. Inorganic alkalizing agents that can be used according to the invention are preferably selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, sodium phosphate, potassium phosphate, sodium silicate, sodium metasilicate, potassium silicate, sodium carbonate and potassium carbonate.

The setting of the desired pH value via a buffer system is also in accordance with the invention. A buffer or buffer system is usually understood to be a mixture of a weak or medium-strength acid (e.g. acetic acid) with a practically completely dissociated neutral salt of the same acid (e.g. sodium acetate). If a little base or acid is added, the pH value hardly changes (buffering). The effect of the buffer substances contained in a buffer solution is based on the capture reaction of hydrogen or hydroxide ions with the formation of weak acids or bases due to their dissociation equilibrium. A buffer system can be formed from a mixture of an inorganic or organic acid and a corresponding salt of this acid. Acids can be buffered by all salts of weak acids and strong bases, bases by salts of strong acids and weak bases. The strong (completely dissociated into ions) hydrochloric acid can be buffered, for example, by adding sodium acetate. According to the equilibrium _H3C -COONa + HCl ⇌ NaCl + _H3C -COOH Hydrochloric acid is converted by sodium acetate to weak acetic acid, forming sodium chloride, which dissociates only to a very small extent in the presence of an excess of sodium acetate. Buffers that act against both acids and bases are mixtures of weak acids and their salts.

Examples of buffer systems known from the literature are acetic acid/sodium acetate, boric acid/sodium borate, phosphoric acid/sodium phosphate and hydrogen carbonate/soda.

The pH value of the agent according to the invention can be adjusted, for example, by adding an inorganic or organic buffer system. In the context of the present invention, an inorganic buffer system is understood to be a mixture of an inorganic acid and its conjugated corresponding inorganic base.

For the purposes of the present invention, an organic buffer system is understood to be a mixture of an organic acid and its conjugate corresponding base. Due to the organic acid residue, the conjugate corresponding base of the organic acid is also organic. The cation present to neutralize the charge of the acid anion can be inorganic or organic.

Examples of inorganic acids are sulfuric acid, hydrochloric acid and phosphoric acid (H ₃ PO ₄ ). Phosphoric acid is a medium-strength acid and is particularly preferred.

A particularly suitable inorganic acid is potassium dihydrogen phosphate. Potassium dihydrogen phosphate has the molecular formula KH ₂ PO ₄ and bears the CAS number 7778-77-0. Potassium dihydrogen phosphate has a molar mass of 136.09 g/mol. It is readily soluble in water (222 g/l at 20 °C) and reacts acidically in water. A 5% solution of potassium dihydrogen phosphate in water has a pH of 4.4.

Another particularly suitable inorganic acid is sodium dihydrogen phosphate. Sodium dihydrogen phosphate has the molecular formula NaH ₂ PO ₄ and has the CAS numbers 7558-80-7 (anhydrate), 10049-21-5 (monohydrate) and 13472-35-0 (dihydrate). The anhydrous sodium dihydrogen phosphate has a molar mass of 119.98 g/mol. Sodium dihydrogen phosphate reacts acidically in aqueous solution.

Dipotassium hydrogen phosphate is particularly preferred as the corresponding salt of the two aforementioned acids. Dipotassium hydrogen phosphate has the molecular formula K ₂ HPO ₄ and bears the CAS numbers 7758-11-4 (anhydrous) and 16788-57-1 (trihydrate). The anhydrous dipotassium hydrogen phosphate has a molar mass of 174.18 g/mol. Dipotassium hydrogen phosphate reacts alkaline in aqueous solution.

Disodium hydrogen phosphate is also particularly preferred as a corresponding salt of the two aforementioned acids. Disodium hydrogen phosphate has the molecular formula Na ₂ HPO ₄ and has the CAS numbers 7558-79-4 (anhydrous), 10028-24-7 (dihydrate), 7782-85-6 (heptahydrate) and 10039-32-4 (dodecahydrate). The anhydrous disodium hydrogen phosphate has a molar mass of 141.96 g/mol. Disodium hydrogen phosphate reacts alkaline in aqueous solution.

The desired pH value can also be adjusted by using an inorganic and/or organic acid. Examples of organic acids are acetic acid, citric acid, succinic acid, tartaric acid, lactic acid, acetic acid, malic acid, malonic acid and maleic acid.

Examples of the corresponding salts of these organic acids are the sodium and potassium salts of citric acid, the sodium and potassium salts of succinic acid, the sodium and potassium salts of tartaric acid, the sodium and potassium salts of lactic acid, the sodium and potassium salts of acetic acid, the sodium and potassium salts of malic acid, the sodium and potassium salts of malonic acid and the sodium and potassium salts of maleic acid.

sequence of procedural steps

As already described above, the pretreatment agent (V) is applied before the application of the dye (F). In this context, it has proven particularly preferable to apply the pretreatment agent (V) to the keratin material, allow it to act for a certain period of time and then rinse it out with water.

• (1) Applizieren des Vorbehandlungsmittels (V) auf die keratinischen Fasern,
• (2) Einwirken des in Schritt (1) applizierten Vorbehandlungsmittels auf die keratinischen Fasern für einen Zeitraum von 2 bis 45 Minuten, bevorzugt von 2 bis 30 Minuten und besonders bevorzugt von 2 bis 20 Minuten,
• (3) Ausspülen des Vorbehandlungsmittels (V) mit Wasser,
• (4) Applizieren des Färbemittels (F) auf die keratinischen Fasern, und
• (5) Einwirken des in Schritt (4) applizierten Färbemittels auf die keratinischen Fasern für einen Zeitraum von 15 Sekunden bis 45 Minuten, bevorzugt von 30 Sekunden bis 30 Minuten und besonders bevorzugt von 1 bis 15 Minuten.

Particularly preferred is therefore a method for dyeing keratin fibers, in particular human hair, comprising the following steps in the order given:

• (1) Applying the pretreatment agent (V) to the keratin fibers,
• (2) allowing the pretreatment agent applied in step (1) 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,
• (3) Rinsing the pretreatment agent (V) with water,
• (4) applying the dye (F) to the keratin fibers, and
• (5) Exposing the dye applied in step (4) to the keratin fibers for a period of time ranging from 15 seconds to 45 minutes, preferably from 30 seconds to 30 minutes, and particularly preferably from 1 to 15 minutes.

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.

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

After the pre-treatment agent (V) has acted on the keratin fibers, it is finally rinsed out with water in step (3). The pre-treatment agent (V) can either be washed out with water alone, i.e. without the aid of a shampoo, or the washing out process can be supported by using a shampoo.

In principle, the user can now freely choose the period between the application of the two agents (V) and (F).

However, it may be preferred that no other agents, such as other conditioners or styling agents, are applied between the application of the two agents (V) and (F). In this way, the maximum period of time between the application of the two agents (V) and (F) is preferably limited to a maximum time interval of 24 hours.

It has been found to be preferable if a period of a maximum of 24 hours, preferably a maximum of 12 hours, more preferably a maximum of 6 hours and most preferably a maximum of 3 hours.

In a further preferred embodiment, a method according to the invention is characterized in that between steps (3) and (4) there is a period of maximum 24 hours, preferably maximum 12 hours, more preferably maximum 6 hours and most preferably maximum 3 hours.

In a further preferred embodiment, a method according to the invention is characterized in that step (4) takes place directly after step (3). Step (4) involves the application of the colorant.

The action of the colorant (F) on the keratin fibers in step (5) can, for example, take place for a period of 15 seconds to 30 minutes, preferably for a period of 30 seconds to 15 minutes, particularly preferably for a period of 1 to 15 minutes.

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

The pretreatment agent according to the invention described above is the ready-to-use pretreatment agent (V) which, in the form in which it is present, can be applied directly to the keratin fibers or hair. As previously written, the pretreatment agent is characterized by its content of at least one oxidizing agent (V-1) and particularly preferably by its content of a combination of carbamide peroxide (V-1) and at least one persulfate (V-2) from the group of ammonium peroxodisulfate, potassium peroxodisulfate and sodium peroxodisulfate.

In principle, both oxidizing agents from groups (V-1) and (V-2) can be packaged together in one product and made available to the user in this form. For reasons of storage stability, however, it has proven particularly preferable if the carbamide peroxide (V-1) and the persulfates (V-2) are packaged in separate products, so that the user has to mix these two products together shortly before use and in this way produce the ready-to-use pretreatment agent (V).

• (1) Bereitstellen eines ersten Mittels, welches Carbamidperoxid enthält
• (2) Bereitstellen eines zweiten Mittels, welches ein oder mehrere Peroxodisulfate aus der Gruppe aus Kaliumperoxodisulfat, Ammoniumperoxodisulfat und Natriumperoxodisulfat enthält,
• (3) Vermischen des ersten und des zweiten Mittels, um ein anwendungsbereites Vorbehandlungsmittel (V) herzustellen,
• (4) Applizieren des in Schritt (3) hergestellten Vorbehandlungsmittels (V) auf die keratinischen Fasern,
• (5) Einwirken des in Schritt (4) applizierten Vorbehandlungsmittels (V) auf die keratinischen Fasern für einen Zeitraum von 2 bis 45 Minuten, bevorzugt von 2 bis 30 Minuten und besonders bevorzugt von 2 bis 20 Minuten,
• (6) Ausspülen des Vorbehandlungsmittels (V) mit Wasser, und
• (7) Applizieren des Färbemittels (F) auf die keratinischen Fasern.

A method according to the invention comprising the following steps is therefore particularly preferred:

• (1) Providing a first agent containing carbamide peroxide
• (2) providing a second agent which contains one or more peroxodisulfates from the group consisting of potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate,
• (3) Mixing the first and second agents to produce a ready-to-use pretreatment agent (V),
• (4) Applying the pretreatment agent (V) prepared in step (3) to the keratin fibers,
• (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,
• (6) Rinsing the pretreatment agent (V) with water, and
• (7) Applying the dye (F) to the keratin fibers.

The first agent, which contains carbamide peroxide (V-1), is particularly preferably a liquid or flowable agent, very particularly preferably a gel, which contains the solvents and/or polyalkylene glycols described above. The second agent, which contains the peroxodisulfate(s) (V-2), is particularly preferably solid or paste-like.

The previously described embodiments and preferred or particularly preferred embodiments apply to the sequence of process steps.

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

Application of the dye as rinse-off or leave-on application

After applying the dye or after it has been applied and allowed to take effect, it can be rinsed out again in a subsequent step. Rinsing can be done with or without the help of a shampoo or conditioner, for example.

However, particularly good results were obtained when the dyeing process according to the invention was designed as a leave-on process, i.e. in this case the dye (F) was not rinsed out immediately after application, but the hair that still had the dye (F) on it was dried. The keratin fibers can be dried at room temperature or assisted by using an external heat source.

A heat treatment means that the keratin material is brought into contact with a heated device or that this heated device is used on or in the keratin material. The keratin material can also be brought into contact with warm/hot air for heat treatment. The device used can be, for example, a hairdryer, a blow dryer, a heat cap, a straightening iron, a curling iron or an infrared lamp.

It has been found that it is preferred if the treatment temperature during the heat treatment is between 40 °C and 210 °C, preferably from 50 °C to 190 °C, more preferably from 50 °C to 170 °C, even more preferably from 50 °C to 150 °C and most preferably from 50 °C to 100 °C. In other words, it has proven to be particularly preferred if the heat treatment is carried out using a device that is heated to a temperature of 40 °C to 210 °C, preferably from 50 °C to 190 °C, more preferably from 50 °C to 170 °C, even more preferably from 50 °C to 150 °C and most preferably from 50 °C to 100 °C.

In a particularly preferred embodiment, a method according to the invention is characterized in that the heat treatment is carried out with a device which is heated to a temperature of 40 °C to 210 °C, preferably from 50 °C to 190 °C, more preferably from 50 °C to 170 °C, even more preferably from 40 °C to 100 °C and most preferably from 40 °C to 80 °C.

In a particularly preferred embodiment, a method according to the invention is characterized by drying the keratin fibers still treated with the colorant (F), preferably drying the keratin fibers still treated with the colorant (F) under the action of heat at a temperature of 40 °C to 210 °C, preferably from 40 °C to 190 °C, more preferably from 40 °C to 170 °C, even more preferably from 40 °C to 100 °C and very particularly preferably from 40 °C to 80 °C.

For example, the keratin material or the hair can be treated with a hairdryer that blows warm or hot air onto the keratin material. This air is particularly preferably between 40 and 100 °C, or even more preferably between 40 and 80 °C. Or the keratin material or the hair can be held under an infrared lamp, which is particularly preferably set to a temperature of 40 to 100 °C. For the purpose of heat treatment, hair can also be pressed between two appropriately tempered plates of a straightening iron, whereby the plates can also be moved along the fiber. The plates of the straightening iron can, for example, be set to a temperature of up to 210 °C.

The duration of the heat treatment can be adapted to the selected temperature range. For example, a heat treatment can be carried out over a period of 5 seconds to 60 minutes, preferably from 15 seconds to 45 minutes, more preferably from 15 seconds to 30 minutes and most preferably from 15 seconds to 15 minutes.

examples

1. Formulations

The following formulations were prepared (all data in wt.% unless otherwise stated): gel with carbamide peroxide Medium (1-1) (wt.%) Medium (1-2) (wt.%) glycerin 19.50 --- 1,2-propanediol 5.00 --- Polyethylene glycol (MW = 380 - 420 g/mol, CAS No. 25322-68-3) 9.50 --- disodium phosphate 1.20 1.20 Phosphoric acid (85% aqueous solution) 0.15 0.15 sodium benzoate 0.04 0.04 sodium hydroxide 0.60 0.60 HEDP (etidronic acid, 60% aqueous solution) 0.50 0.50 carbamide peroxide 17.00 --- Carbopol Ultrez 21 (Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Lubrizol) 1.5 1.5 hydrogen peroxide (50% aqueous solution) --- 23.2 water (distilled) ad 100 ad 100 persulfate bleaching powder Medium (2) (wt.%) Sodium silicate/sodium disilicate (Britesil C 265, PQ Corporation) CAS No. 1344-09-8 36.00 magnesium carbonate 9.80 sodium hexametaphosphate 0.20 Tylose H 1000000 YP2 (Hydroxyethylcellulose, SE Tylose, Shin Etsu) 0.35 Cekol 50000 (carboxymethylcellulose, sodium salt, CAS No. 9004-32-4, CP Kelco) 2.00 EDTA, disodium salt 1.6 Aerosil 50 (Evonic, hydrophilic fumed silica) 0.40 Ariabel Blue 300302 (Silicic acid aluminum sodium salt, sulfurized Pigment Blue 29) 0.15 potassium peroxodisulfate 32.00 ammonium peroxodisulfate 10.00 Paraffinum Liquidum ad 100 coloring agent (FM) F1 (wt.%) F2 (wt.%) Chitosan (MW = 100,000 - 300,000 g/mol, Sigma Aldrich) 1.00 1.00 Unipure Red LC 3079 (Pigment Red 7, Cas No. 5281-04-9 CI 15850) 0.40 - Blue 60 (Pigment Blue 15, CI 74160, BASF) - 0.40 acetic acid 1.00 1.00 water (distilled) ad 100 ad 100

2. Application to strands

The first ready-to-use pretreatment agent (V) was prepared by mixing 2 parts by weight of carbamide peroxide gel (agent (1-1)) and one part by weight of persulfate bleaching powder (agent (2)). This agent is referred to below as agent (V1).

The second ready-to-use pretreatment agent (V) was prepared by mixing 2 parts by weight of the aqueous hydrogen peroxide solution (agent (1-2)) and one part by weight of persulfate bleaching powder (agent (2)). This agent is referred to below as agent (V2).

The pre-treatment agent (V) prepared in this way was applied to each strand of hair (Kerling). 4.0 g of pre-treatment agent (V) per gram of hair was applied to the strands, massaged in and left to work for 30 minutes at room temperature. The strands were then rinsed with water. The dye (F) was then applied to the still damp hair. 2.0 g of dye (F) per gram of hair was massaged in and left to work for 1 minute. The strands still containing the dye were then dried with a standard hairdryer.

The dyed strands were visually assessed by a trained person under the daylight lamp.

Reference strands were treated directly with the respective dye (F) without using the pre-treatment agent (V). Before applying the dye (F), the reference strand was only moistened with water, then the dye was applied according to the procedure described above. These strands were also visually assessed by a trained person under the daylight lamp.

After coloring, each colored strand was subjected to five 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 shampoo per gram of hair). The strand was then rinsed with lukewarm tap water for 30 seconds and dried.

After each hair wash, the respective strand was again visually assessed under the daylight lamp.

The hair strands were assessed for their color intensity using a scale from 1 (very low color intensity) to 5 (very high color intensity). The evenness of the coloring was also assessed using a scale from 1 (very uneven coloring) to 5 (very even coloring).
Comparison = staining without pretreatment
Invention = successive application of pretreatment agent (V-1) or (V-2) and dye (F) 0 HW = color result directly after dyeing shade: red Number of washes (HW), color intensity example (V) (F) 0 HW 1 HW 2 HW 3 HW 4 HW 5 HW 1 Comparison --- (F1) 4 3 3 2 1 1 2 invention (V1) (F1) 5 4 4 3 3 3 3 invention (V2) (F1) 5 4 4 3 3 3 5 = high intensity 1 = low intensity shade: red Number of washes (HW), uniformity of coloring example (V) (F) 0 HW 1 HW 2 HW 3 HW 4 HW 5 HW 1 Comparison - -- (F1) 5 4 4 2 1 1 2 invention (V1) (F1) 5 5 5 4 4 3 3 invention (V2) (F1) 5 5 5 4 3 3 5 = very even coloring 1 = uneven coloring shade: blue Number of washes (HW), color intensity example (V) (F) 0 HW 1 HW 2 HW 3 HW 4 HW 5 HW 1 Comparison - (F2) 5 4 3 3 1 1 2 invention (V1) (F2) 5 4 4 4 4 3 3 invention (V2) (F2) 5 4 4 3 3 3 5 = high intensity 1 = low intensity shade: blue Number of washes (HW), uniformity of coloring example (V) (F) 0 HW 1 HW 2 HW 3 HW 4 HW 5 HW 1 Comparison - (F2) 5 4 3 2 2 1 2 invention (V1) (F2) 5 4 4 4 4 3 3 invention (V2) (F2) 5 4 4 3 3 3 5 = very even coloring 1 = uneven coloring

The strands dyed with the process according to the invention (V1)/(F1), (V2)/(F1), (V1)/(F2) and (V2)/(F2) showed improved wash fastness and a more uniform color result compared to the corresponding dyeing without pretreatment (V).

3. Measuring hair damage

To measure the hair damage associated with the pretreatment, the respective pretreatment agent (V1) or (V2) was applied to hair strands (Kerling company). 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 for 30 minutes at room temperature. The strands were then rinsed with water and dried.

The amount of cysteic acid present in the hair strand was then determined using quantitative NIR spectroscopy.

The spectra were recorded using an MPA ^{TM FT} -NIR spectrometer from Bruker Optik GmbH. The infrared range covers the wave number range from 12500 cm ^-1 to 4000 cm ^-1 and is characteristic of overtone and combination vibrations of, for example, CH, OH and NH groups.

The measurements of the samples were carried out using the integrating sphere module at six different sample positions in diffuse reflection. The wave number range from 7300 cm ^-1 to 4020 cm ^-1 was chosen for the analysis of the measured NIR spectra.

The NIR spectra of cystine show characteristic absorption bands in the wave number range from 6200 cm ^-1 to 5500 cm ^-1 . If the hair changes due to more severe damage (ie the cysteic acid content in the hair increases), this affects the bands characteristic of cysteic acid at 5020 cm ^-1 to 4020 cm ^-1 in the NIR spectrum. The quantitative evaluation of the NIR spectra was carried out using computer aided analysis.

The NIR analysis value provides the amount of mol cysteic acid / 100 mol amino acid. The higher this cysteic acid value, the more severe the hair damage: pretreatment agent (V1) pretreatment agent (V2) 0.7 [mol cysteic acid / 100 mol amino acid] 2.6 [mol cysteic acid / 100 mol amino acid]

Pretreatment with pretreatment agent (V1) was associated with reduced hair damage compared to pretreatment with (V2).

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 19847883 A1 [0007]
• WO 2021190810 A1 [0008, 0009]

Claims (15)

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 (V-1) contains at least one oxidizing agent, and - application of a dye (F) to the keratin fibers, wherein the dye in a cosmetic carrier (F-1) contains at least one chitosan and/or a chitosan derivative, and (F-2) at least one pigment. procedure according to claim 1 , characterized in that the pretreatment agent (V) contains one or more oxidizing agents (V-1) from the group consisting of carbamide peroxide, potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate. Method according to one of the Claims 1 until 2 , characterized in that the pretreatment agent (V) - based on the total weight of the pretreatment agent (V) - contains (V-1) 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. % of carbamide peroxide, and (V-2) one or more peroxodisulfates 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. %. Method according to one of the Claims 1 until 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-C ₁ -C ₆ -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 most preferably from 12.0 to 25.0 wt.%. Method according to one of the Claims 1 until 4 , 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) 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 most 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. Method according to one of the Claims 1 until 5 , 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. Method according to one of the Claims 1 until 6 , characterized in that the colorant (F) contains at least one chitosan and/or a chitosan derivative (F-1) with a molecular weight of 20,000 to 800,000 g/mol, preferably 50,000 to 600,000 g/mol, more preferably 80,000 to 450,000 g/mol and most preferably 100,000 to 300,000 g/mol. Method according to one of the Claims 1 until 7 , characterized in that the colorant (F) - based on the total weight of the colorant (F) - contains one or more chitosans and/or chitosan derivatives in a total amount of 0.1 to 10.0 wt.%, preferably 0.2 to 8.0 wt.%, more preferably 0.5 to 6.0 wt.% and most preferably 0.7 to 2.0 wt.%. Method according to one of the Claims 1 until 8 , characterized in that the colorant (F) contains at least inorganic pigment (F-2), which is preferably selected from the group of colored metal oxides, metal hydroxides, metal oxide hydrates, silicates, metal sulfides, complex metal cyanides, metal sulfates, bronze pigments and/or from colored pigments based on mica or mica which are coated with at least one metal oxide and/or one metal oxychloride. Method according to one of the Claims 1 until 9 , characterized in that the colorant (F) contains at least one organic pigment (F-2), which is preferably selected from the group consisting of carmine, quinacridone, phthalocyanine, sorghum, blue pigments with the color index numbers CI 42090, CI 69800, CI 69825, CI 73000, CI 74100, CI 74160, yellow pigments with the color index numbers CI 11680, CI 11710, CI 15985, CI 19140, CI 20040, CI 21100, CI 21108, CI 47000, CI 47005, green pigments with the color index numbers CI 61565, CI 61570, CI 74260, orange pigments with the color index numbers CI 11725, CI 15510, CI 45370, CI 71105, red pigments with the color index numbers CI 12085, CI 12120, CI 12370, CI 12420, CI 12490, CI 14700, CI 15525, CI 15580, CI 15620, CI 15630, CI 15800, CI. 15850, CI 15865, CI 15880, CI 17200, CI 26100, CI 45380, CI 45410, CI 58000, CI 73360, CI 73915 and/or CI 75470. Method according to one of the Claims 1 until 10 , characterized in that the colorant (F) contains at least one pigment (F-2) which is selected from the group of pigments based on a lamellar substrate platelet, pigments based on a lenticular substrate platelet and vacuum metallized pigments. Method according to one of the Claims 1 until 11 , characterized in that the colorant (F) - based on the total weight of the colorant - contains one or more pigments (F-2) in a total amount of 0.01 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. %. Method according to one of the Claims 1 until 12 , comprising the following steps: (1) providing a first agent which contains carbamide peroxide (2) providing a second agent which contains one or more peroxodisulfates from the group consisting of potassium peroxodisulfate, ammonium peroxodisulfate and sodium peroxodisulfate, (3) mixing the first and second agents to produce a ready-to-use pretreatment agent (V), (4) applying the pretreatment agent (V) produced in step (3) to the keratin fibers, (5) allowing the pretreatment agent (V) applied in step (4) to act on the keratin fibers for a period of 2 to 45 minutes, preferably 2 to 30 minutes and particularly preferably 2 to 20 minutes, (6) rinsing out the pretreatment agent (V) with water, and (7) applying the colorant (F) to the keratin fibers. Method according to one of the Claims 1 until 13 , characterized in that between the application of the pretreatment agent (V) and the application of the colorant (F) there is a period of maximum 24 hours, preferably maximum 12 hours, more preferably maximum 6 hours and most preferably maximum 3 hours. Method according to one of the Claims 1 until 14 , characterized by drying the keratin fibers still coated with the colorant (F), preferably drying the hair still coated with the colorant (F), under heat at a temperature of 40 °C to 210 °C, preferably from 40 °C to 190 °C, more preferably from 40 °C to 170 °C, even more preferably from 40 °C to 100 °C and most preferably from 40 °C to 80 °C.