Method for decolouring keratinous material dyed with an organosilicon compound and a pigment

Abstract

A method for decolouring keratinous material, which has been dyed by the application of at least one organosilicon compound and at least one pigment, by applying a decolouring agent comprising at leas

Description

Technical Field 5 The present application is in the field of cosmetics and relates to a process for decolouring keratinous material that has been dyed by applying at least one organosilicon compound and at least one pigment. The decolouring agent applied in this process is characterized by its content of at least one aluminium salt as defined in claim 1. 10 A second object of the present application is a process for dyeing and later decolouring keratinous material, in which first a dyeing agent containing an organosilicon compound and a pigment is applied to the keratin, and laterdecolouring is carried outby applying the decolouring agent described above. A third object of the present application is the use of the previously described decolouring agent for 15 decolouring dyed keratinous material, preferably for decolouring keratinous material which has been dyed by applying at least one organosilicon compound and at least one pigment. Background The change in shape and colour of keratin fibres, especially hair, is an important area of modern 20 cosmetics. To change the hair colour, the expert knows various dyeing systems depending on dyeing requirements. Oxidation dyes are usually used for permanent, intensive dyeings with good fastness properties and good grey coverage. Such dyes usually contain oxidation dye precursors, so-called developer components and coupler components, which form the actual dyes with one another under the influence of oxidizing agents, such as hydrogen peroxide. Oxidation dyes are characterized by 25 very long-lasting dyeing results. When direct dyes are used, ready-made dyes diffuse from the dye into the hair fibre. Compared to oxidative hair dyeing, the dyeings obtained with direct dyes have a shorter shelf life and quicker wash ability. Dyes with direct dyes usually remain on the hair for a period of between 5 and 20 washes. 30 The use of colour pigments is known for short-term colour changes on the hair and / or skin. Colour pigments are generally understood to be insoluble, colouring substances. These are present in undissolved form as small particles in the dye formulation and are only deposited from the outside on the hair fibres and / or the skin surface. Therefore, they can usually be removed again without residue by a few washes with detergents containing surfactants. Various products of this type are 35 available on the market under the name hair mascara. Recently, a new dyeing system has received attention in which dyes are dyed by applying a combination of a pigment, an organic silicon compound, and a polymer. This new dyeing system is described, for example, in EP 2168633 B1. 07 03 25 When these organic silicon compounds are applied to keratinous material, a film or coating is formed on the keratinous material, which completely envelops the keratinous material and in this way strongly influences the properties of the keratinous material. If the application is carried out in the 5 presence of a dye compound, for example a pigment, the pigments are embedded in this film or coating. The film dyed by the pigment remains on the keratin material or keratin fibres. The resulting colourations are said to be particularly resistant to shampooing. Even with this dyeing process, it may happen that the dyeing is to be partially or completely reversed 10 for various reasons. Partial removal of the dye may be necessary, for example, if the dyeing result on the fibres is darker than desired. On the other hand, complete removal of the stain may also be desired in some cases. For example, it is conceivable that the hair is to be dyed in a certain shade for a specific occasion and the original colour is to be regained after a few days. 15 Various methods are described in the state of the art for removing the colourations produced with silanes and pigments. In WO 2021 / 028095 A1, for example, corresponding stains are removed with a solvent and an alkalizing agent, and WO 2021 / 028093 A1 uses solvents and fluorine compounds for decolouring. WO 2022 / 0058064 A1 and WO 2022 / 0058065 A1 also use fluorine compounds in combination with other components for decolouring. However, these prior art decolouring methods 20 are not yet effective enough, or they use fluorine compounds, which can be further improved in terms of their ecological or toxicological profile. The object of the present invention was therefore to provide a decolouring agent for decolouring dyed keratinous material, in particular fibres and above all hair, which had previously been dyed by 25 applying at least one organosilicon compound, in particular a Ci-Ce alkoxysilane, and at least one pigment. Here, the decolouring should be as complete as possible, so that the colouration of the keratinous material can ideally be restored to its original state. The discolouration should be long-lasting and even, and the discoloured keratin fibres should not suffer any shifts in shade or unevenness in the colour result. In addition, the keratinous material should be damaged as little as 30 possible by the decolouring agent and the ingredients should be toxicologically and ecologically safe. Surprisingly, it has now been found that this task can be solved very well if keratinous material, which has previously been coloured with at least one organosilicon compound and with at least one pigment, is treated with a decolouring agent which contains at least one aluminium salt as defined in 35 claim 1. Description 07 03 25 A first object of the present invention is a method for decolourizing keratinous material which has been dyed by application of at least one organosilicon compound and at least one pigment, wherein a decolouring agent containing (a) at least one aluminium salt as defined in claim 1 5 is applied to the dyed keratin material. Decolouring keratinous material Keratinous material includes hair, skin, nails (such as fingernails and / or toenails). Wool, furs and feathers also fall under the definition of keratinous material. 10 Preferably, keratinous material is understood to be human hair, human skin and human nails, especially fingernails and toenails. Keratinous material is understood to be human hair in particular. In the context of the present invention, the term “decolouring agent” is understood to mean that a 15 dye produced by the application of at least one organosilicon compound and at least one pigment can be removed again on the keratinous material. During dyeing, the keratin material or keratin fibre is coated with a dyed film formed from the organosilicon compounds and the pigments. According to the invention, the application of the decolouring agent takes place after the application of the dyeing agent, and the decolouring agent is able to remove this dyed film from the keratin material again. 20 Characteristic of the method according to the invention is the application of the decolouring agent to keratin material previously dyed by application of at least one organosilicon compound and at least one pigment. Preference is given to a method for decolouring hair which has been dyed by applying at least one 25 organosilicon compound and at least one pigment, wherein a decolouring agent comprising (a) at least one aluminium salt as defined in claim 1 is applied to the dyed hair. Dyeing with the use of organosilicon compounds 30 In the process according to the invention, the decolouring agent is applied to previously dyed keratin material. At least one organosilicon compound is used on the keratin material in the previous dyeing process. Organic silicon compounds, alternatively called organosilicon compounds, are compounds which 35 either have a direct silicon-carbon bond (Si-C) or in which the carbon is bonded to the silicon atom via an oxygen, nitrogen or sulphur atom. The organic silicon compounds of the invention are preferably compounds containing one to three silicon atoms. Organic silicon compounds preferably contain one or two silicon atoms. 07 03 25 The decolouring agent works particularly well on dyed keratin material if an organic Ci-Ce alkoxysilane was used in the previous dyeing. The organic C-i-Cb alkoxysilane(s) are organic, non-polymeric silicon compounds, preferably selected 5 from the group of silanes containing one, two or three silicon atoms. According to IUPAC rules, the term silane stands for a group of chemical compounds based on a silicon skeleton and hydrogen. In organic silanes, the hydrogen atoms are completely or partially replaced by organic groups such as (substituted) alkyl groups and / or alkoxy groups. 10 A characteristic feature of the Ci-Ce alkoxysilanes according to the invention is that at least one Ci-Ce alkoxy group is directly bonded to a silicon atom. The C-i-Cb alkoxysilanes according to the invention thus comprise at least one structural unit R’R“R“‘Si-O-(Ci-C6 alkyl) where the radicals R', R" and R'" represent the three remaining bond valences of the silicon atom. 15 The C-i-Ce alkoxy group or groups bonded to the silicon atom are very reactive and are hydrolysed at high rates in the presence of water, the reaction rate depending, among other things, on the number of hydrolysable groups per molecule. If the hydrolysable C-i-Cb alkoxy group is an ethoxy group, the organic silicon compound preferably contains a structural unit R'R"R"'Si-O-CH2-CH3. The 20 radicals R‘, R“ and R'“ again represent the three remaining free valences of the silicon atom. Even the addition of small amounts of water leads first to hydrolysis and then to a condensation reaction between the organic alkoxysilanes. For this reason, both the organic alkoxysilanes and their condensation products can be used for dyeing purposes. 25 A condensation product is understood to be a product that is formed by the reaction of at least two organic C-i-Cb alkoxysilanes with the elimination of water and / or with the elimination of a C-i-Cb alkanol. The condensation products can, for example, be dimers, or even trimers or oligomers, where in the condensation products are always in balance with the monomers. Depending on the amount 30 of water used or consumed in the hydrolysis, the equilibrium shifts from monomeric Ci-Cb alkoxysilane to condensation product. In a very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at 35 least one organic Ci-Cb alkoxysilane and / or a condensation product thereof and by application of at least one pigment. 07 03 25 The organic Ci-Ce alkoxysilanes may be, for example, compounds selected from silanes having one, two or three silicon atoms, the organic silicon compound further comprising one or more basic chemical functions. 5 This basic group can be, for example, an amino group, an alkylamino group or a dialkylamino group, which is preferably connected to a silicon atom via a linker. Preferably, the basic group is an amino group, a C1-C6 alkylamino group or a di(C1-C6)alkylamino group. A particularly preferred method according to the invention is characterised in that the decolouring 10 agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof and by application of at least one pigment, wherein the Ci-Ce alkoxysilane further comprises one or more basic chemical functions.. Particularly good results were obtained when the decolouring agent was applied to keratin material 15 which had previously been dyed with Ci-Ce alkoxysilanes of formula (S-l) and / or (S-ll). Since, as already described above, hydrolysis / condensation already occurs at traces of moisture, dyeing of keratin material with Ci-Cb alkoxysilanes of formula (S-l) and / or (S-ll) also includes the application of their condensation products. 20 In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane of formula (S-l) and / or (S-ll) and a pigment, RiR2N-L-Si(OR3)a(R4)b (S-l) 25 where Ri, R2 independently represent a hydrogen atom or a Ci-Ce alkyl group, - L is a linear or branched divalent C1-C20 alkylene group, - R3, R4 independently of one another represent a Ci-Ce alkyl group, 30 - a, stands for an integer from 1 to 3, and b stands for the integer 3 - a, and (R5O)c(R6)dSi-(A)e-[NR7-(A’)]f-[O-(A”)]g-[NR8-(A’”)]h-Si(R6’)d(OR5’)c' (S-ll), 35 where R5, R5‘, R5“, R6, R6‘ and R6“ independently represent a Ci-Cealkyl group, A, A', A", A'“ and A““ independently represent a linear or branched divalent C1-C20 alkylene group, 07 03 25 R? and Rs independently represent a hydrogen atom, a Ci-Ce alkyl group, a hydroxy Ci-Cb alkyl group, a C2-C6 alkenyl group, an amino Ci-Cb alkyl group or a group of formula (S-lll),, 5 - (A““)-Si(R6“)d“(OR5“)c“ (S-lll), - c, stands for an integer from 1 to 3, - d stands for the integer 3 - c, - c' stands for an integer from 1 to 3, 10 - d‘stands for the integer 3 - c', - c“ stands for an integer from 1 to 3, - d“ stands for the integer 3 - c“, - e stands for 0 or 1, - f stands for 0 or 1, 15 - g stands for 0 or 1, - h stands for 0 or 1, - with the proviso that at least one of the remainders of e, f, g and h is different from 0. The substituents Ri, R2, R3, R4, Rs, Rs‘, Rs“, Re, Rs', Rs“, R7, Rs, L, A, A‘, A", A'“ and A““ in the 20 compounds of formula (S-1) and (S- II) are explained below as examples: Examples of a Ci-Ce alkyl group are the groups methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl and t-butyl, n-pentyl and n-hexyl. Propyl, ethyl and methyl are preferred alkyl radicals. Examples of a C2-Cs alkenyl group are vinyl, allyl, but-2-enyl, but-3-enyl and isobutenyl, preferred C2-C6 alkenyl radicals are vinyl and allyl. Preferred examples of a hydroxy Ci-Cb alkyl group are a hydroxymethyl group, a 25 2-hydroxyethyl group, a 2-hydroxypropyl, a 3-hydroxypropyl group, a 4-hydroxy butyl group, a 5-hydroxypentyl group and a 6-hydroxyhexyl group; a 2-hydroxyethyl group is particularly preferred. Examples of an amino Ci-Cb alkyl group are the aminomethyl group, the 2-aminoethyl group, the 3-aminopropyl group. The 2-aminoethyl group is particularly preferred. Examples of a linear divalent C1-C20 alkylene group include the methylene group (-CH2-), the ethylene group (-CH2-CH2-), the 30 propylene group (-CH2-CH2-CH2-) and the butylene group (-CH2-CH2-CH2-CH2-). The propylene group (-CH2-CH2-CH2-) is particularly preferred. From a chain length of 3 C atoms, divalent alkylene groups can also be branched. Examples of branched divalent, bivalent C3-C20 alkylene groups are (-CH2-CH(CH3)-) and (-CH2-CH(CH3)-CH2-). 35 In the organic silicon compounds of formula (S-l) RiR2N-L-Si(OR3)a(R4)b (S-l), 07 03 25 the radicals Ri and R2 independently represent a hydrogen atom or a Ci-Ce alkyl group. Particularly preferably, the radicals R1 and R2 both represent a hydrogen atom. In the central part of the organic silicon compound is the structural unit or the linker -L- which stands for a linear or branched, divalent C1-C20 alkylene group. The divalent C1-C20 alkylene group can alternatively also be referred to as a divalent C1-C20 alkylene group, which means that each grouping -L- can form two bonds. Preferably -L- stands for a linear, divalent C1-C20 alkylene group. Further preferably -L- stands for a linear divalent Ci-Ce alkylene group. Particularly preferred -L stands fora methylene group (-CH2-), an ethylene group (-CH2-CH2-), propylene group (-CH2-CH2-CH2-) or butylene (-CH2-CH2-CH2-CH2-). In particular, L stands for a propylene group (-CH2-CH2-CH2-) The organic silicon compounds of formula (S-l) according to the invention RiR2N-L-Si(OR3)a(R4)b (S-l), each have the silicon-containing group -Si(ORs)a(R4)bat one end. In the terminal structural unit -Si(OR3)a(R4)bthe radicals R3 and R4 independently represent a Ci-Ce alkyl group, particularly preferably R3 and R4 independently represent a methyl group or an ethyl group. Here a stands for an integer from 1 to 3, and b stands for the integer 3 - a. If a stands for the number 3, then b is equal to 0. If a stands for the number 2, then b is equal to 1. If a stands for the number 1, then b is equal to 2. The application of the decolouring agent according to the invention was particularly successful if the keratin material had previously been dyed with an organic Ci-Ce alkoxysilane of formula (S-l) in which the radicals R3, R4 independently represent a methyl group or an ethyl group. Furthermore, the use of the decolouring agent according to the invention was also particularly successful when the keratin material was previously dyed with an organic Ci-Ce alkoxysilane of formula (S-l), in which the radical a represents the number 3. In this case, the radical b represents the number 0. In a further preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane of formula (I) and / or a condensation product thereof and by application of at least one pigment, 07 03 25 5 RiR2N-L-Si(OR3)a(R4)b (S-i), where - Ri, Rs both represent a hydrogen atom, and - L represents a linear, divalent Ci-Ce alkylene group, preferably a propylene group (-CH2-CH2-CH2-) or an ethylene group (-CH2-CH2-), 10 - Rs represents an ethyl group or a methyl group, - R4 represents a methyl group or an ethyl group, - a stands for the number 3 and - b stands for the number 0. 15 Silicon compounds of formula (I) which can be removed particularly well by subsequent application of the decolouring agent according to the invention are - (3-aminopropyl)triethoxysilane - (2-aminoethyl)triethoxysilane - (2-aminoethyl)trimethoxysilane 07 03 25 - (3-dimethylaminopropyl)triethoxysilane - (3-dimethylaminopropyl)trimethoxysilane - (2-dimethylaminoethyl)triethoxysilane. - (2-dimethylaminoethyl)trimethoxysilane and / or 07 03 25 In a further preferred embodiment, a method according to the invention is characterised in that the decolouring agent is applied to keratin material which has been dyed by application of at least one 5 organic Ci-Ce alkoxysilane and / or a condensation product thereof and by application of at least one pigment, wherein the organic Ci-Cb alkoxysilane is selected from the group consisting of - (3-aminopropyl)triethoxysilane - (3-aminopropyl)trimethoxysilane - (2-aminoethyl)triethoxysilane 10 - (2-aminoethyl)trimethoxysilane - (3-dimethylaminopropyl)triethoxysilane - (3-dimethylaminopropyl)trimethoxysilane - (2-dimethylaminoethyl)triethoxysilane and / or - (2-dimethylaminoethyl)trimethoxysilane. 15 The aforementioned organic silicon compound of formula (I) is commercially available. (3-aminopropyl)trimethoxysilane, for example, can be purchased from Sigma-Aldrich. Also (3-aminopropyl)triethoxysilane is commercially available from Sigma-Aldrich. 20 In a further embodiment of the method according to the invention, the keratin material can also be dyed beforehand by applying one or more organic Ci-Ce alkoxysilanes of formula (S-ll), (R5O)c(R6)dSi-(A)e-[NR7-(A’)]f-[O-(A”)]g-[NR8-(A’”)]h-Si(R6’)d(OR5’)c (S-ll). 25 The organosilicon compounds of formula (S-ll) according to the invention each carry at their two ends the silicon-containing groupings (R5O)c(R6)dSi- and -Si(R6’)d(OR5’)c. In the central part of the molecule of formula (S-ll) there are the groups -(A)e- and -[NR?-(A’)]f-and -[O-(A”)]g- and -[NR8-(A’”)]h- Here, each of the radicals e, f, g and h can independently stand for 30 the number 0 or 1, with the proviso that at least one of the radicals e, f, g and h is different from 0. In other words, an organic silicon compound of formula (II) according to the invention contains at least one grouping from the group consisting of-(A)- and -[NR?-(A’)]- and -[O-(A”)]- and -[NR8-(A”’)]-. 07 03 25 In the two terminal structural units (RsO)c(R6)dSi- and - Si(R6’)d(OR5’)c', the radicals R5, R5', R5" independently represent a Ci-Ce alkyl group. The radicals R6, R6' and R6" independently represent a Ci-Ce alkyl group. 5 Here c stands for an integer from 1 to 3, and d stands for the integer 3 - c. If c stands for the number 3, then d equals 0. If c stands for the number 2, then d equals 1. If c stands for the number 1, then d equals 2. Analogously, c' stands for an integer from 1 to 3, and d1 stands for the integer 3 - c'. If c' stands for 10 the number 3, then d' equals 0. If c' stands for the number 2, then d' equals 1. If c' stands for the number 1, then d' equals 2. Dyeings with the best wash fastness values could be obtained if the radicals c and c' both stand for the number 3. In this case d and d' both stand for the number 0. 15 In a further preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-C@ alkoxysilane of formula (II) and / or a condensation product thereof and by application of at least one pigment, 20 (R5O)c(R6)dSi-(A)e-[NR7-(A’)]f-[O-(A”)]g-[NR8-(A’”)]h-Si(R6’)d'(OR5’)c (S-ll), where - R5 and R5' independently represent a methyl group or an ethyl group, 25 - c and c' both stand for the number 3 and - d and d' both stand for the number 0. When c and c' are both 3 and d and d' are both 0, the organic silicon compounds according to the invention correspond to the formula (S-lla) 30 (R5O)3Si-(A)e-[NR7-(A’)HO-(A”)]g-[NR8-(A’”)]h-Si(OR5’)3 (S-lla). The radicals e, f, g and h can independently stand forthe number 0 or 1, whereby at least one radical from e, f, g and h is different from zero. The abbreviations e, f, g and h therefore define which of the 35 groupings-(A)e- and -[NR?-(A’)]f- and -[O-(A”)]g- and -[NR8-(A”’)]h-are located in the centre part of the organic silicon compound of formula (II). 07 03 25 In this context, the presence of certain groupings has proved particularly beneficial. Particularly good results could be obtained if at least two ofthe radicals e, f, g and h stand forthe number 1. Especially preferred e and f both stand for the number 1. Furthermore, g and h both stand forthe number 0. 5 When e and f are both 1 and g and h are both 0, the organic silicon compounds according to the invention are represented by formula (S-llb) (R5O)c(R6)dSi-(A)-[NR7-(A’)]-Si(R6’)d-(OR5’)c’ (S-llb). 10 The radicals A, A', A", A'" and A"" independently represent a linear or branched, divalent C1-C20 alkylene group. Preferably the radicals A, A', A", A'" and A"" independently represent a linear, divalent C1-C20 alkylene group. Further preferably the radicals A, A', A", A'" and A"" independently represent a linear divalent Ci-Ce alkylene group. 15 The divalent C1-C20 alkylene group can alternatively also be referred to as a divalent C1-C20 alkylene group, which means that each grouping A, A', A", A"1 and A"" can form two bonds. In particular, the radicals A, A', A", A'" and A"" independently represent a methylene group (-CH2-), an ethylene group (-CH2-CH2-), a propylene group (-CH2-CH2-CH2-) or a butylene group (-CH2-CH2-20 CH2-CH2-). Most particularly preferably, the radicals A, A', A", A'" and A"" represent a propylene group (-CH2-CH2-CH2-). If the radical f represents the number 1, then the organic silicon compound of formula (II) according to the invention contains a structural grouping -[NR?-(A’)]-. 25 If the radical f represents the number 1, then the organic silicon compound of formula (II) according to the invention contains a structural grouping -[NR8-(A”’)]-- Here the radicals R7 and R8 independently represent a hydrogen atom, a Ci-Ce alkyl group, a hydroxy- Ci-Ce alkyl group, a C2-C6 alkenyl group, an amino Ci-Ce alkyl group or a grouping of 30 formula (S-lll) - (A““)-Si(R6“)d“(OR5“)c“          (S-lll). Particularly preferably the radicals R7 and R8 independently represent a hydrogen atom, a methyl 35 group, a 2-hydroxyethyl group, a 2-alkenyl group, a 2-aminoethyl group ora grouping of formula (S-III). 07 03 25 If the radical f represents the number 1 and the radical h represents the number 0, the organic silicon compound according to the invention contains the grouping [NR?-(A’)] but not the grouping -[NRs-(A’”)].. If the radical R7 now stands for a grouping of formula (III), the organic silicone compound comprises 3 reactive silane groups. 5 In a further preferred embodiment, a method according to the invention is characterised in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Cr-Ce alkoxysilane of formula (S-l I) and / or a condensation product thereof and by application of at least one pigment, 10 (R5O)c(R6)dSi-(A)e-[NR7-(A’)]f-[O-(A”)]g-[NR8-(A’”)]h-Si(R6’)d(OR5’)c' (S-ll) where 15 - e and f both stand for the number 1, - g and h both stand for the number 0, - A and A' independently represent a linear, divalent Ci-Cb alkylene group and - R7 represents a hydrogen atom, a methyl group, a 2-hydroxyethyl group, a 2-alkenyl group, a 2-20 aminoethyl group or a group of formula (S- III). In a further preferred embodiment, a method according to the invention is characterised in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic C-i-Cs alkoxysilane of formula (S-ll) and / or a condensation product thereof and by application 25 of at least one pigment, where - e and f both stand for the number 1, - g and h both stand for the number 0, - A and A' independently represent a methylene group (-CH2-), an ethylene group (-CH2-CH2-) or a 30 propylene group (-CH2-CH2-CH2), and - R7 represents a hydrogen atom, a methyl group, a 2-hydroxyethyl group, a 2-alkenyl group, a 2-aminoethyl group or a group of formula (S- III). 35 Silicon compounds of formula (S-ll) which can be removed particularly well by subsequent application of the decolouring agent according to the invention are - 3-(trimethoxysilyl)-N-[3-(trimethoxysilyl)propyl]-1 -propanamine 07 03 25 - N-methyl-3-(trimethoxysilyl)-N-[3-(trimethoxysilyl)propyl]-1 -propanamine -N-methyl-3-(triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-pro panamine - 2-[bis[3-(trimethoxysilyl)propyl]amino]-ethanol - 2-[bis[3-(triethoxysilyl)propyl]amino]-ethanol 07 03 25 - 3-(trimethoxysilyl)-N,N-bis[3-(trimethoxysilyl)propyl]-1-propanamine 10 - 3-(triethoxysilyl)-N,N-bis[3-(triethoxysilyl)propyl]-1-propanamine 07 03 25 - N,N-bis[3-(trimethoxysilyl)propyl]-2-propene-1-amine 07 03 25 - N,N-bis[3-(triethoxysilyl)propyl]-2-propene-1-amine 5 The aforementioned organic silicon compounds of formula (S-ll) are commercially available. Bis(trimethoxysilylpropyl)amine with CAS number 82985-35-1 can be purchased, for example, from Sigma-Aldrich. Bis[3-(triethoxysilyl)propyl]amine with CAS numberl 3497-18-2 can be purchased, for example, from 10 Sigma-Aldrich. N-methyl-3-(trimethoxysilyl)-N-[3-(trimethoxysilyl)propyl]-1-propanamine is alternatively known as bis(3-trimethoxysilylpropyl)-N-methylamine and can be purchased commercially from Sigma-Aldrich or Fluorochem. 3-(triethoxysilyl)-N,N-bis[3-(triethoxysilyl)propyl]-1-propanamine with the CAS number 18784-74-2 15 can be purchased, for example, from Fluorochem or Sigma-Aldrich. In a further preferred embodiment, a method according to the invention is characterised in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof and by application of at least one 20 pigment, wherein the organic Ci-Ce alkoxysilane is selected from the group consisting of - 3-(trimethoxysilyl)-N-[3-(trimethoxysilyl)propyl]-1 -propanamine - 3-(triethoxysilyl)-N-[3-(triethoxysilyl) propyl]-1 -propanamine - N-methyl-3-(trimethoxysilyl)-N-[3-(trimethoxysilyl)propyl]-1 -propanamine - N-methyl-3-(triethoxysilyl)-N-[3-(triethoxysilyl) propyl]-1-propanamine 25 - 2-[bis[3-(trimethoxysilyl) propyl]amino]-ethanol 07 03 25 - 2-[bis[3-(triethoxysilyl)propyl]amino]-ethanol - 3-(trimethoxysilyl)-N,N-bis[3-(trimethoxysilyl) propyl]-1 -propanamine - 3-(triethoxysilyl)-N,N-bis[3-(triethoxysilyl) propyl]-1-propanamine - N1 ,N1-bis[3-(trimethoxysilyl)propyl]-1,2-ethanediamine, 5 - N1,N1-bis[3-(triethoxysilyl)propyl]-1,2-ethanediamine, - N,N-bis[3-(trimethoxysilyl)propyl]-2-Propen-1 -amine and / or - N,N-bis[3-(triethoxysilyl)propyl]-2-propen-1-amine. In further dyeing / decolouring experiments, it has also proved to be particularly advantageous if at 10 least one organic Ci-Ce alkoxysilane of formula (S-IV) was used to dye the keratin material in the process according to the invention RgSi(ORio)k(Rn)m (S-IV). 15 The compounds of formula (S-IV) are organic silicon compounds selected from silanes having one, two or three silicon atoms, wherein the organic silicon compound comprises one or more hydrolysable groups per molecule. The organic silicon compound(s) of formula (S- IV) may also be referred to as silanes of the alkyl-20 Ci-Ce-alkoxysilane type, R9Si(ORio)k(Rn)m (S-IV), where - Rs represents a C1-C12 alkyl group, 25 - R10 represents a Ci-Cb alkyl group, - R11 represents a C-i-Cb alkyl group - k is an integer from 1 to 3, and - m stands for the integer 3 - k. 30 In a further particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane of formula (S-IV) and / or a condensation product thereof and by application of at least one pigment, 35                                     R9Si(ORw)k(Rii)m (S-IV), where Rs represents a C1-C12 alkyl group, R10 represents a Ci-Cb alkyl group, 07 03 25 Rn represents a Ci-Ce alkyl group k stands for an integer from 1 to 3, and m stands for the integer 3 - k. 5 In the organic Ci-Ce alkoxysilanes of formula (S- IV), the Rg radical represents a C1-C12 alkyl group. This C1-C12 alkyl group is saturated and can be linear or branched. Preferably, Rg represents a linear Ci-Cs alkyl group. Preferably Rg stands for a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group or an n-dodecyl group. Particularly preferably, Rg represents a methyl group, an ethyl group or an n-octyl group. 10 In the organic silicon compounds of formula (S- IV), the radical R10 represents a Ci-Ce alkyl group. Particularly preferably, R10 represents a methyl group or an ethyl group. In the organic silicon compounds of formula (S- IV), the radical Rn represents a Ci-Ce alkyl group. 15 Particularly preferably, Rn represents a methyl group or an ethyl group. Furthermore k stands for an integer from 1 to 3, and m stands for the integer 3 - k. If k stands for the number 3, then m equals 0. If k stands for the number 2, then m equals 1. If k stands for the number 1, then m equals 2. 20 Very good decolouration results were obtained when the keratin material was first dyed with an organic Ci-Ce alkoxysilane of formula (S-IV) in which the radical k stands for the number 3. In this case the radical m stands for the number 0. 25 Organic silicon compounds of formula (S-IV) which are particularly suitable for solving the problem according to the invention are - methyltrimethoxysilane O\ 0 30 - methyltriethoxysilane - ethyltrimethoxysilane 07 03 25 10 - n-propyltrimethoxysilane (also known as propyltrimethoxysilane) - n-propyltriethoxysilane (also known as propyltriethoxysilane) - n-hexyltrimethoxysilane (also known as hexyltrimethoxysilane) 07 03 25 - n-hexyltriethoxysilane (also known as hexyltriethoxysilane) 10 - n-octyltrimethoxysilane (also known as octyltrimethoxysilane) - n-octyltriethoxysilane (also known as octyltriethoxysilane) - n-dodecyltrimethoxysilane (also referred to as dodecyltrimethoxysilane) and / or 07 03 25 - n-dodecyltriethoxysilane (also referred to as dodecyltriethoxysilane). In a further preferred embodiment, a method according to the invention is characterised in that the 10 decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof and by application of at least one pigment, wherein the organic Ci-Ce alkoxysilane is selected from the group consisting of - methyltrimethoxysilane, - methyltriethoxysilane, 15 -ethyltrimethoxysilane, - ethyltriethoxysilane, - propyltrimethoxysilane - propyltriethoxysilane - hexyltrimethoxysilane, 20 - hexyltriethoxysilane, - octyltrimethoxysilane, - octyltriethoxysilane, - dodecyltrimethoxysilane, and / or - dodecyltriethoxysilane. The corresponding hydrolysis or condensation products are, for example, the following compounds: 5 Hydrolysis of C-i-Cb alkoxysilane of formula (S-l) with water (reaction scheme using the example of 3-aminopropyltriethoxysilane): 07 03 25 OEt OEt + H2o -----► + Et0H OEt OEt 10 Depending on the amount of water used, the hydrolysis reaction can also take place several times per Ci-Ce alkoxysilane used: OEt OH + 2 1EO ------► + 2 EtOH OEt OEt 15 or OEt OH H2N\ / -\ / Si 0Et + 3 H2° ----+ 3 EtOH OEt OH 20 Hydrolysis of Ci-Ce alkoxysilane of formula (S-IV) with water (reaction scheme using methyltrimethoxysilane as an example): OMe OMe I                                                                                                                                                                                             | CH3—Si—OMe + H2O -----► CH3—Si—OH + MeOH I                                                                                                                                                                                             I OMe OMe Depending on the amount of water used, the hydrolysis reaction can also take place several times per Ci-Ce alkoxysilane used: OMe I CH3—Si—OMe + 2 H2O I OMe OH I CH3—Si—OH + 2 MeOH I OMe OMe I CH3—Si—OMe + 3 H2O OMe OH I CH3—Si—OH + 3 MeOH OH Possible condensation reactions include (shown using the mixture (3-aminopropyl)triethoxysilane and methyltrimethoxysilane): 07 03 25 OEt OEt and / or OEt OEt nh2 nh2 and / or OEt OH and / or OMe Si—C OMe and / or h2n OMe I Si—C OMe and / or 07 03 25 and / or OEt OEt OMe --Si—OH OMe OMe OMe —Si—OH + Si—OMe OMe OMe OMe OMe ___ MeO—Si—O—Si—OMe MeOH In the above exemplary reaction schemes the condensation to a dimer is shown in each case, but further condensations to oligomers with several silane atoms are also possible and also preferred. Both partially hydrolysed and fully hydrolysed Ci-Ce alkoxysilanes of formula (S-l), which undergo condensation with as yet unreacted, partially or fully hydrolysed Ci-Ce alkoxysilanes of formula (S-I), can take part in these condensation reactions. In this case, the Ci-Ce alkoxysilanes of formula (S-I) react with themselves. Furthermore, both partially hydrolysed and fully hydrolysed Ci-Ce alkoxysilanes of formula (S-l), which undergo condensation with as yet unreacted, partially or fully hydrolysed Ci-Ce alkoxysilanes of formula (S-IV), can also take part in the condensation reactions. In this case, the Ci-Ce alkoxysilanes of formula (S-l) react with the Ci-Ce alkoxysilanes of formula (S-IV). 07 03 25 Furthermore, both partially hydrolysed and fully hydrolysed Ci-Ce alkoxysilanes of formula (S-IV) which undergo condensation with as yet unreacted, partially or fully hydrolysed C-i-Cb alkoxysilanes of formula (S-IV) can also take part in the condensation reactions. In this case, the Ci-Ce alkoxysilanes of formula (S- IV) react with themselves. 5 Dyeing with the use of pigments In the process according to the invention, the decolouring agent is applied to previously dyed keratin material. In addition to the at least one organosilicon compound, in particular the organic Ci-Ce alkoxysilane, at least one pigment is also used in the dyeing process. 10 Pigments within the meaning of the present invention are understood to be dyeing compounds which have a solubility in water at 25°C of less than 0.5g / L, preferably less than 0.1 g / L, still more preferably less than 0.05g / L. Water solubility can be determined, for example, by the method described below: 0.5g of the pigment are weighed in a beaker. A magnetic stir bar is added. Then one litre of distilled 15 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 0.5g / L. If the pigment-water mixture cannot be assessed visually due to the high intensity of the possibly finely dispersed pigment, the mixture is filtered. If a proportion of undissolved pigments remains on the filter paper, the solubility of the pigment is below 0.5g / L. 20 Suitable colour pigments can be of inorganic and / or organic origin. In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by 25 application of at least one inorganic and / or organic pigment. Preferred colour pigments are selected from synthetic or natural inorganic pigments. Inorganic colour pigments of natural origin can be produced, for example, from chalk, ochre, umber, green earth, burnt Terra di Siena or graphite. Furthermore, black pigments such as iron oxide black, coloured 30 pigments such as ultramarine or iron oxide red as well as fluorescent or phosphorescent pigments can be used as inorganic colour pigments. Particularly suitable are coloured metal oxides, hydroxides and oxide hydrates, mixed-phase pigments, sulphur-containing silicates, silicates, metal sulphides, complex metal cyanides, metal 35 sulphates, chromates and / or molybdates. In particular, preferred colour pigments are black iron oxide (Cl 77499), yellow iron oxide (Cl 77492), red and brown iron oxide (Cl 77491), manganese violet (Cl 77742), ultramarine (sodium aluminium sulfo silicates, Cl 77007, pigment blue 29), chromium oxide hydrate (CI77289), iron blue (ferric ferrocyanides, C177510) and / or carmine (cochineal). 07 03 25 According to the invention, coloured pearlescent pigments are also particularly preferred colour pigments. These are usually mica- and / or mica-based and can be coated with one or more metal oxides. Mica belongs to the layer 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, mainly 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 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 colour of the respective pigments can be varied by varying the layer thickness of the metal oxide(s). In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one pigment selected from the group consisting of coloured metal oxides, metal hydroxides, metal oxide hydrates, silicates, metal sulphides, complex metal cyanides, metal sulphates, bronze pigments and / or coloured mica or mica-based pigments coated with at least one metal oxide and / or a metal oxychloride. In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one pigment selected from the group consisting of mica or mica-based pigments, coloured with one or more metal oxides selected from the group consisting of titanium dioxide (Cl 77891), black iron oxide (Cl 77499), yellow iron oxide (Cl 77492), red and / or brown iron oxide (Cl 77491, Cl 77499), manganese violet (Cl 77742), ultramarine (sodium aluminium sulfo silicates, Cl 77007, pigment blue 29), chromium oxide hydrate (Cl 77289), chromium oxide (Cl 77288) and / or iron blue (ferric ferrocyanide, Cl 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. Particularly preferred colour pigments with the trade name Colorona® are, for example: Colorona Copper, Merck, MICA, Cl 77491 (IRON OXIDES) Colorona Passion Orange, Merck, Mica, Cl 77491 (Iron Oxides), Alumina Colorona Patina Silver, Merck, MICA, Cl 77499 (IRON OXIDES), Cl 77891 (TITANIUM DIOXIDE) Colorona RY, Merck, Cl 77891 (TITANIUM DIOXIDE), MICA, Cl 75470 (CARMINE) Colorona Oriental Beige, Merck, MICA, Cl 77891 (TITANIUM DIOXIDE), Cl 77491 (IRON OXIDES) Colorona Dark Blue, Merck, MICA, TITANIUM DIOXIDE, FERRIC FERROCYANIDE 07 03 25 Colorona Chameleon, Merck, Cl 77491 (IRON OXIDES), MICA Colorona Aborigine Amber, Merck, MICA, Cl 77499 (IRON OXIDES), Cl 77891 (TITANIUM DIOXIDE) Colorona Blackstar Blue, Merck, Cl 77499 (IRON OXIDES), MICA 5 Colorona Patagonian Purple, Merck, MICA, Cl 77491 (IRON OXIDES), Cl 77891 (TITANIUM DIOXIDE), Cl 77510 (FERRIC FERROCYANIDE) Colorona Red Brown, Merck, MICA, Cl 77491 (IRON OXIDES), Cl 77891 (TITANIUM DIOXIDE) Colorona Russet, Merck, Cl 77491 (TITANIUM DIOXIDE), MICA, Cl 77891 (IRON OXIDES) Colorona Imperial Red, Merck, MICA, TITANIUM DIOXIDE (Cl 77891), D&C RED NO. 30 (Cl 73360) 10 Colorona Majestic Green, Merck, Cl 77891 (TITANIUM DIOXIDE), MICA, Cl 77288 (CHROMIUM OXIDE GREENS) Colorona Light Blue, Merck, MICA, TITANIUM DIOXIDE (Cl 77891), FERRIC FERROCYANIDE (Cl 77510) Colorona Red Gold, Merck, MICA, Cl 77891 (TITANIUM DIOXIDE), Cl 77491 (IRON OXIDES) 15 Colorona Gold Plus MP 25, Merck, MICA, TITANIUM DIOXIDE (Cl 77891), IRON OXIDES (Cl 77491) Colorona Carmine Red, Merck, MICA, TITANIUM DIOXIDE, CARMINE Colorona Blackstar Green, Merck, MICA, Cl 77499 (IRON OXIDES) Colorona Bordeaux, Merck, MICA, Cl 77491 (IRON OXIDES) 20 Colorona Bronze, Merck, MICA, Cl 77491 (IRON OXIDES) Colorona Bronze Fine, Merck, MICA, Cl 77491 (IRON OXIDES) Colorona Fine Gold MP 20, Merck, MICA, Cl 77891 (TITANIUM DIOXIDE), Cl 77491 (IRON OXIDES) Colorona Sienna Fine, Merck, Cl 77491 (IRON OXIDES), MICA 25 Colorona Sienna, Merck, MICA, Cl 77491 (IRON OXIDES) Colorona Precious Gold, Merck, Mica, Cl 77891 (Titanium dioxide), Silica, Cl 77491 (Iron oxides), Tin oxide Colorona Sun Gold Sparkle MP 29, Merck, MICA, TITANIUM DIOXIDE, IRON OXIDES, MICA, Cl 77891, Cl 77491 (EU) 30 Colorona Mica Black, Merck, Cl 77499 (Iron oxides), Mica, Cl 77891 (Titanium dioxide) Colorona Bright Gold, Merck, Mica, Cl 77891 (Titanium dioxide), Cl 77491(lron oxides) Colorona Blackstar Gold, Merck, MICA, Cl 77499 (IRON OXIDES) Other particularly preferred colour pigments with the trade name Xirona® are for example: 35 Xirona Golden Sky, Merck, Silica, Cl 77891 (Titanium Dioxide), Tin Oxide Xirona Caribbean Blue, Merck, Mica, Cl 77891 (Titanium Dioxide), Silica, Tin Oxide Xirona Kiwi Rose, Merck, Silica, Cl 77891 (Titanium Dioxide), Tin Oxide Xirona Magic Mauve, Merck, Silica, Cl 77891 (Titanium Dioxide), Tin Oxide. 07 03 25 In addition, particularly preferred colour pigments with the trade name Unipure® are for example: Unipure Red LC 381 EM, Sensient Cl 77491 (Iron Oxides), Silica Unipure Black LC 989 EM, Sensient, Cl 77499 (Iron Oxides), Silica Unipure Yellow LC 182 EM, Sensient, Cl 77492 (Iron Oxides), Silica 5 In a further embodiment of the method according to the invention, the keratin material may also have been dyed with at least one organic pigment prior to application ofthe decolouring agent. The organic pigments according to the invention are correspondingly insoluble, organic dyes or 10 colour lacquers, which may be selected, for example, from the group of nitroso, nitro, azo, xanthene, anthraquinone, isoindoline, isoindolinone, quinacridone, perinone, perylene, diketopyrrolopyorrole, indigo, thioindido, dioxazine and / or triarylmethane compounds. Examples of particularly suitable organic pigments are carmine, quinacridone, phthalocyanine, 15 sorghum, blue pigments with the colour index numbers Cl 42090, Cl 69800, Cl 69825, Cl 73000, Cl 74100, Cl 74160, yellow pigments with the colour index numbers Cl 11680, Cl 11710, Cl 15985, Cl 19140, Cl 20040, Cl 21100, Cl 21108, Cl 47000, Cl 47005, green pigments with the colour index numbers Cl 61565, Cl 61570, Cl 74260, orange pigments with the colour index numbers Cl 11725, Cl 15510, Cl 45370, Cl 71105, red pigments with the colour index numbers Cl 12085, Cl 12120, Cl 20 12370, Cl 12420, Cl 12490, Cl 14700, Cl 15525, Cl 15580, Cl 15620, Cl 15630, Cl 15800, Cl 15850, Cl 15865, Cl 15880, Cl 17200, Cl 26100, Cl 45380, Cl 45410, Cl 58000, Cl 73360, Cl 73915 and / or Cl 75470. In another particularly preferred embodiment, a method according to the invention is characterized 25 in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic pigment selected from the group consisting of carmine, quinacridone, phthalocyanine, sorghum, blue pigments having the colour index numbers Cl 42090, Cl 69800, Cl 69825, Cl 73000, Cl 74100, Cl 74160, yellow pigments having the colour index numbers Cl 11680, Cl 11710, Cl 15985, Cl 19140, Cl 20040, Cl 21100, Cl 21108, Cl 47000, Cl 47005, green pigments 30 with colour index numbers Cl 61565, Cl 61570, Cl 74260, orange pigments with colour index numbers Cl 11725, Cl 15510, Cl 45370, Cl 71105, red pigments with the colour index numbers Cl 12085, Cl 12120, Cl 12370, Cl 12420, Cl 12490, Cl 14700, Cl 15525, Cl 15580, Cl 15620, Cl 15630, Cl 15800, Cl 15850, Cl 15865, Cl 15880, Cl 17200, Cl 26100, Cl 45380, Cl 45410, Cl 58000, Cl 73360, Cl 73915 and / or Cl 75470. 35 The organic pigment can also be a lake. In the context ofthe invention, the term lake is understood to mean particles comprising a layer of absorbed dyes, the unit of particle and dye being insoluble under the above conditions. The particles can, for example, be inorganic substrates, which can be aluminium, silica, calcium borosilicate, calcium aluminium borosilicate or even aluminium. For example, alizarin lake can be used. 07 03 25 Due to their excellent light and temperature resistance, dyeing with the aforementioned pigments is 5 particularly preferred. It is also preferred ifthe pigments used have a certain particle size. This particle size leads on the one hand to an even distribution of the pigments in the formed polymer film and on the other hand avoids a rough hair or skin feeling after application of the cosmetic product. Therefore, it is advantageous according to the invention ifthe at least one pigment has an average particle size Dso of 1.0 to 50pm, preferably of 5.0 to 45pm, preferably of 10 to 40pm, in particular of 14 to 30pm. 10 The average particle size Dso, for example, can be determined using dynamic light scattering (DLS). Pigments with a specific shaping may also have been used to dye the keratin material. For example, a pigment based on a lamellar and / or a lenticular substrate platelet can be used. Furthermore, dye based on a substrate platelet comprising a vacuum metallized pigment is also possible. 15 The substrate platelets of this type have an average thickness of at most 50nm, preferably less than 30nm, particularly preferably at most 25nm, for example at most 20nm. The average thickness of the substrate platelets is at least 1nm, preferably at least 2.5nm, particularly preferably at least 5nm, for example at least 10nm. Preferred ranges for substrate platelet thickness are 2.5 to 50nm, 5 to 50nm, 20 10 to 50nm; 2.5 to 30nm, 5 to 30nm, 10 to 30nm; 2.5 to 25nm, 5 to 25nm, 10 to 25nm, 2.5 to 20nm, 5 to 20nm, and 10 to 20nm. Preferably, each substrate plate has a thickness that is as uniform as possible. Due to the low thickness of the substrate platelets, the pigment exhibits particularly high covering 25 power. The substrate platelets have a monolithic structure. Monolithic in this context means consisting of a single closed unit without fractures, stratifications or inclusions, although structural changes may occur within the substrate platelets. The substrate platelets are preferably homogeneously 30 structured, i.e. there is no concentration gradient within the platelets. In particular, the substrate platelets do not have a layered structure and do not have any particles distributed in them. The size of the substrate platelet can be adjusted to the respective application purpose, especially the desired effect on the keratinous material. Typically, the substrate platelets have an average 35 largest diameter of about 2 to 200pm, especially about 5 to 100pm. In a preferred design, the aspect ratio, expressed by the ratio of the average size to the average thickness, is at least 80, preferably at least 200, more preferably at least 500, more preferably more than 750. The average size of the uncoated substrate platelets is the d50 value of the uncoated 30 07 03 25 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 analysed was predispersed in isopropanol for 3 minutes. 5 The substrate platelets can be composed of any material that can be formed into platelet shape. They can be of natural origin, but also synthetically produced. Materials from which the substrate platelets can be constructed include metals and metal alloys, metal oxides, preferably aluminium oxide, inorganic compounds and minerals such as mica and (semi-)precious stones, and plastics. 10 Preferably, the substrate platelets are constructed of metal (alloy). Any metal suitable for metallic lustre pigments can be used. Such metals include iron and steel, as well as all air and water resistant (semi)metals such as platinum, zinc, chromium, molybdenum and silicon, and their alloys such as aluminium bronzes and brass. Preferred metals are aluminium, 15 copper, silver and gold. Preferred substrate platelets include aluminium platelets and brass platelets, with aluminium substrate platelets being particularly preferred. Lamellar substrate platelets are characterized by an irregularly structured edge and are also referred to as “cornflakes” due to their appearance. 20 Due to their irregular structure, pigments based on lamellar substrate platelets generate a high proportion of scattered light. In addition, pigments based on lamellar substrate platelets do not completely cover the existing colour of a keratinous material, and effects analogous to natural greying can be achieved, for example. 25 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. 30 Vacuum metallized pigments (VMP) can be obtained, for example, by releasing metals, metal alloys or metal oxides from suitably coated films. They are characterised by a particularly low thickness of the substrate platelets in the range of 5 to 50nm and a particularly smooth surface with increased reflectivity. Substrate platelets comprising a vacuum metallized pigment are also referred to as VMP substrate platelets in the context of this application. VMP substrate platelets of aluminium can be 35 obtained, for example, by releasing aluminium from metallised films. The metal or metal alloy substrate plates can be passivated, for example by anodizing (oxide layer) or chromating. 07 03 25 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 create a light-dark flop but no colour impression. A colour impression can be created, for example, by optical interference effects. Such pigments can 5 be based on at least single-coated substrate platelets. These show interference effects by superimposing differently refracted and reflected light beams. Accordingly, pigments based on a coated lamellar substrate platelet, are preferred. The substrate platelet preferably has at least one coating B of a highly refractive metal oxide having a coating 10 thickness of at least 50nm. There is preferably another coating A between coating B and the surface of the substrate platelet. If necessary, there is a further coating C on layer B, which is different from layer B underneath. Suitable materials for coatings A, B and C are all substances that can be applied to the substrate 15 platelets in a film-like and permanent manner and, in the case of coatings A and B, have the required optical properties. Generally, coating part of the surface of the substrate platelets is sufficient to obtain a pigment with a glossy effect. For example, only the top and / or bottom of the substrate platelets may be coated, with the side surface(s) omitted. Preferably, the entire surface of the optionally passivated substrate platelets, including the side surfaces, is covered by coating B. The 20 substrate platelets are therefore completely enveloped by coating B. This improves the optical properties of the pigment and increases its mechanical and chemical resistance. The above also applies to layer A, and preferably also to layer C, if present. Although multiple coatings A, B and / or C may be present in each case, the coated substrate platelets 25 preferably have only one coating A, B and, if present, C in each case. Coating B is composed of at least one highly refractive metal oxide. Highly refractive materials have a refractive index of at least 1.9, preferably at least 2.0, and particularly preferably at least 2.4. Preferably, coating B comprises at least 95% by weight, more preferably at least 99% by weight, of 30 high refractive index metal oxide(s). Coating B has a thickness of at least 50nm. Preferably, the thickness of coating B is no more than 400nm, particularly preferably no more than 300nm. 35 Highly refractive metal oxides suitable for coating B are preferably selectively light-absorbing (i.e. coloured) metal oxides, such as iron (III) oxide (a- and y-Fe2O3, red), cobalt(ll) oxide (blue), chromium (III) oxide (green), titanium (III) oxide (blue, usually present in admixture with titanium oxynitrides and titanium nitrides), and vanadium (V) oxide (orange), and mixtures thereof. Colourless high-index oxides such as titanium dioxide and / or zirconium oxide are also suitable. 07 03 25 Coating B may contain a selectively absorbing dye, preferably 0.001 to 5% by weight, particularly preferably 0.01 to 1% by weight, in each case based on the total amount of coating B. Organic and inorganic dyes that can be stably incorporated into a metal oxide coating are suitable. Coating A preferably has at least one low refractive index metal oxide and / or metal oxide hydrate. Preferably, coating A comprises at least 95% by weight, more preferably at least 99% by weight, of low refractive index metal oxide (hydrate). Low refractive index materials have a refractive index of 1.8 or less, preferably 1.6 or less. Low refractive index metal oxides suitable for coating A include, for example, silicon (di)oxide, silicon oxide hydrate, aluminium oxide, aluminium oxide hydrate, boron oxide, germanium oxide, manganese oxide, magnesium oxide, and mixtures thereof, with silicon dioxide being preferred. Coating A preferably has a thickness of 1 to 100nm, particularly preferably 5 to 50nm, especially preferably 5 to 20nm. Preferably, the distance between the surface of the substrate platelets and the inner surface of coating B is at most 100nm, particularly preferably at most 50nm, especially preferably at most 20nm. By ensuring that the thickness of coating A, and therefore the distance between the surface of the substrate platelets and coating B, is within the range specified above, it is possible to ensure that the pigments have a high covering power. If the pigment based on a lamellar substrate platelet has only one layer A, it is preferred that the pigment has a lamellar substrate platelet of aluminium and a layer A of silica. If the pigment based on a lamellar substrate platelet has a layer A and a layer B, it is preferred that the pigment has a lamellar substrate platelet of aluminium, a layer A of silica and a layer B of iron oxide. According to a preferred embodiment, the pigments have a further coating C of a metal oxide (hydrate), which is different from the underlying coating B. Suitable metal oxides include silicon (di)oxide, silicon oxide hydrate, aluminium oxide, aluminium oxide hydrate, zinc oxide, tin oxide, titanium dioxide, zirconium oxide, iron (III) oxide, and chromium (III) oxide. Silicon dioxide is preferred. Coating C preferably has a thickness of 10 to 500nm, particularly preferably 50 to 300nm. By providing coating C, for example based on TiO2, better interference can be achieved while maintaining high covering power. Layers A and C serve in particular as corrosion protection as well as chemical and physical stabilization. Particularly preferred layers A and C are silica oxide or aluminium oxide, applied by the 33 07 03 25 sol-gel process. This method comprises dispersing the uncoated lamellar substrate platelets or the lamellar substrate platelets already coated with layer A and / or layer B in a solution of a metal alkoxide such as tetraethyl orthosilicate or aluminium triisopropanolate (usually in a solution of organic solvent or a mixture of organic solvent and water with at least 50% by weight of organic solvent such as a Ci to C4 alcohol), and adding a weak base or acid to hydrolyse the metal alkoxide, thereby forming a film of the metal oxide on the surface of the (coated) substrate platelets. Layer B can be produced, for example, by hydrolytic decomposition of one or more organic metal compounds and / or by precipitation of one or more dissolved metal salts, as well as any subsequent post-treatment (for example, transfer of a formed hydroxide-containing layer to the oxide layers by annealing). Although each of the coatings A, B and / or C may be composed of a mixture of two or more metal oxide (hydrate)s, each of the coatings is preferably composed of one metal oxide (hydrate). The pigments based on coated lamellar or lenticular substrate platelets or the pigments based on coated VMP substrate platelets preferably have a thickness of 70 to 500nm, particularly preferably 100 to 400nm, especially preferably 150 to 320nm, for example 180 to 290nm. Due to the low thickness of the substrate platelets, the pigment exhibits particularly high covering power. The low thickness of the coated substrate platelets is achieved in particular by keeping the thickness of the uncoated substrate platelets low, but also by adjusting the thicknesses of the coatings A and, if present, C to as small a value as possible. The thickness of coating B determines the colour impression of the pigment. The adhesion and abrasion resistance of pigments based on coated substrate platelets in keratinous material can be significantly increased by additionally modifying the outermost layer, layer A, B orC depending on the structure, with organic compounds such as silanes, phosphoric acid esters, titanates, borates or carboxylic acids. In this case, the organic compounds are bonded to the surface of the outermost, preferably metal oxide-containing, layer A, B, or C. The outermost layer denotes the layer that is spatially farthest from the lamellar substrate platelet. The organic compounds are preferably functional silane compounds that can bind to the metal oxide-containing layer A, B, or C. These can be either monofunctional or bifunctional compounds. Examples of bifunctional organic compounds are methacryloxypropenyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3- acryloxypropyltrimethoxysilane, 2-acryloxyethyltrimethoxysilane, 3- methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 2- methacryloxyethyltriethoxysilane, 2-acryloxyethyltriethoxysilane, 3- methacryloxypropyltris(methoxyethoxy)silane, 3-methacryloxypropyltris(butoxyethoxy)silane, 3- methacryloxypropyltris(propoxy)silane, 3-methacryloxypropyltris(butoxy)silane, 3- acryloxypropyltris(methoxyethoxy)silane, 3-acryloxypropyltris(butoxyethoxy)silane, 3- 07 03 25 aeryloxypropyltris(butoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylethyldichlorosilane, vinylmethyldiacetoxysilane, vinylmethyldichlorosilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, phenylvinyldiethoxysilane, or phenylallyldichlorosilane. Furthermore, a modification with a monofunctional silane, in particular an alkylsilane or arylsilane, 5 can be carried out. This has only one functional group, which can covalently bond to the surface pigment based on coated lamellar substrate platelets (i.e. to the outermost metal oxide-containing layer) or, if not completely covered, to the metal surface. The hydrocarbon residue of the silane points away from the pigment. Depending on the type and nature of the hydrocarbon residue of the silane, a varying degree of hydrophobicity of the pigment is achieved. Examples of such silanes include 10 hexadecyltrimethoxysilane, propyltrimethoxysilane, etc. Particularly preferred are pigments based on silica-coated aluminium substrate platelets surface-modified with a monofunctional silane. Octyltrimethoxysilane, octyltriethoxysilane, hecadecyltrimethoxysilane and hecadecyltriethoxysilane are particularly preferred. Due to the changed surface properties I hydrophobization, an improvement can be achieved in terms of adhesion, abrasion resistance and alignment in the application. 15 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 platelet are available, for example, under the name 20 Alegrace® Gorgeous from the company Schlenk Metallic Pigments GmbH. Pigments based on a substrate platelet comprising a vacuum metallized pigment are available, for example, under the name Alegrace® Marvelous or Alegrace® Aurous from the company Schlenk Metallic Pigments GmbH. 25 Dyeing with the use of polymers In addition to the organosilicon compound(s), in particular the organic Ci-Ce alkoxysilanes and the at least one pigment, at least one film-forming polymer can also be used for dyeing the keratin material, in particular the keratin fibres. 30 It has been found that the colourations obtained by applying the combination of organic Ci-Ce alkoxysilane, pigment and film-forming polymer are particularly resistant and therefore especially difficult to decolorize. Surprisingly, it has been found that the application of the decolouring agent according to the invention is also able to decolorize these dyeings excellently. 35 In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof, by application of at least one pigment and by application of at least one film-forming polymer. 07 03 25 Polymers are macromolecules with a molecular weight of at least 1000g / mol, preferably of at least 2500g / mol, particularly preferably of at least 5000g / mol, which consist of identical, repeating organic units. The polymers of the present invention may be synthetically produced polymers which are 5 manufactured by polymerisation of one type of monomer or by polymerisation of different types of monomer which are structurally different from each other. If the polymer is produced by polymerising one type of monomer, it is called a homo-polymer. If structurally different monomer types are used in polymerisation, the resulting polymer is called a copolymer. 10 The maximum molecular weight of the polymer depends on the degree of polymerisation (number of polymerised monomers) and the batch size and is determined by the polymerisation method. For the purposes of the present invention, it is preferred that the maximum molecular weight of the filmforming hydrophobic polymer (c) is not more than 107g / mol, preferably not more than 106g / mol and particularly preferably not more than 105g / mol. 15 In terms of the invention, a film-forming polymer is a polymer which is capable of forming a film on a substrate, for example on a keratinous material or a keratinous fibre. The formation of a film can be demonstrated, for example, by looking at the keratin material treated with the polymer under a microscope. 20 The film-forming polymers previously applied in the dyeing step can be hydrophilic or hydrophobic. In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by 25 application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof, by application of at least one pigment and by application of at least one film-forming, hydrophobic polymer. A hydrophobic polymer is a polymer that is soluble in water at 25°C (760mmHg) of less than 1 % by 30 weight. The water solubility of the film-forming, hydrophobic polymer can, for example, be determined in the following way. 1.0g of the polymer is placed in a beaker. It is filled up to 100g with water. A magnetic stir bar is added and the mixture is heated to 25°C on a magnetic stirrer while stirring. It is stirred for 35 60 minutes. The aqueous mixture is then visually assessed. If the polymer-water mixture cannot be assessed visually due to a high turbidity of the mixture, the mixture is filtered. If a proportion of undissolved polymer remains on the filter paper, the solubility of the polymer is less than 1% by weight. 07 03 25 These include acrylic acid-type polymers, polyurethanes, polyesters, polyamides, polyureas, cellulose polymers, nitrocellulose polymers, silicone polymers, acrylamide-type polymers and polyisoprenes. Particularly well suited film-forming, hydrophobic polymers are, for example, polymers from the group of copolymers of acrylic acid, copolymers of methacrylic acid, homopolymers or copolymers of acrylic acid esters, homopolymers or copolymers of methacrylic acid esters, homopolymers or copolymers of acrylic acid amides, homopolymers or copolymers of methacrylic acid amides, copolymers of vinylpyrrolidone, copolymers of vinyl alcohol, copolymers of vinyl acetate, homopolymers or copolymers of ethylene, homopolymers or copolymers of propylene, homopolymers or copolymers of styrene, polyurethanes, polyesters and / or polyamides. In a further particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one film-forming, hydrophobic polymer selected from the group consisting of copolymers of acrylic acid, copolymers of methacrylic acid, homopolymers or copolymers of acrylic acid esters, homopolymers or copolymers of methacrylic acid esters, homopolymers or copolymers of acrylic acid amides, homopolymers or copolymers of methacrylic acid amides, copolymers of vinylpyrrolidone, copolymers of vinyl alcohol, copolymers of vinyl acetate, homopolymers or copolymers of ethylene, homopolymers or copolymers of propylene, homopolymers or copolymers of styrene, polyurethanes, polyesters and / or polyamides. Film-forming hydrophobic polymers selected from the group of synthetic polymers, polymers obtained by radical polymerisation or natural polymers have proven to be particularly suitable for dyeing. Other particularly well-suited film-forming hydrophobic polymers can be selected from the homopolymers or copolymers of olefins, such as cycloolefins, butadiene, isoprene or styrene, vinyl ethers, vinyl amides, the esters or amides of (meth)acrylic acid having at least one C1-C20 alkyl group, an aryl group or a C2-C10 hydroxyalkyl group. Other film-forming hydrophobic polymers may be selected from the homopolymers or copolymers of isooctyl (meth)acrylate; isonononyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; lauryl (meth)acrylate; isopentyl (meth)acrylate; n-butyl (meth)acrylate); isobutyl (meth)acrylate; ethyl (meth)acrylate; methyl (meth)acrylate; tert-butyl (meth)acrylate; stearyl (meth)acrylate; hydroxyethyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; 3-hydroxypropyl (meth)acrylate and / or mixtures thereof. 07 03 25 Other film-forming hydrophobic polymers may be selected from the homopolymers or copolymers of (meth)acrylamide; N-alkyl-(meth)acrylamides, in particular those with C2-C18 alkyl groups, such as N-ethylacrylamide, N-tert-butylacrylamide, Ie N-octylcrylamide; N-di(C1-C4)alkyl-(meth)acrylamide. 5 Other preferred anionic copolymers are, for example, copolymers of acrylic acid, methacrylic acid or their Ci-Cs alkyl esters, as they are marketed under the INCI Declaration Acrylates Copolymers. A suitable commercial product is, for example, Aculyn® 33 from Rohm &Haas. Copolymers of acrylic acid, methacrylic acid or their Ci-Ce alkyl esters and the esters of an ethylenically unsaturated acid and an alkoxylated fatty alcohol are also preferred. Suitable ethylenically unsaturated acids are 10 especially acrylic acid, methacrylic acid and itaconic acid; suitable alkoxylated fatty alcohols are especially steareth-20 or ceteth-20. Very particularly preferred polymers on the market are, for example, Aculyn® 22 (Acrylates / Steareth-20 Methacrylate Copolymer), Aculyn® 28 (Acrylates / Beheneth-25 Methacrylate Copolymer), 15 Structure 2001® (Acrylates / Steareth-20 Itaconate Copolymer), Structure 3001® (Acrylates / Ceteth-20 Itaconate Copolymer), Structure Plus® (Acrylates / Aminoacrylates C10-30 Alkyl PEG-20 Itaconate Copolymer), Carbopol® 1342, 1382, Ultrez 20, Ultrez 21 (Acrylates / C 10-30 Alkyl Acrylate Crosspolymer), Synthalen W 2000® (Acrylates / Pa I meth-25 Acrylate Copolymer) or the Rohme und Haas distributed Soltex® OPT (Acrylates / C 12-22 Alkyl methacrylate Copolymer). 20 The homopolymers and copolymers of N-vinylpyrrolidone, vinylcaprolactam, vinyl-(C1-C6)alkylpyrrole, vinyloxazole, vinylthiazole, vinylpyrimidine, vinylimidazole can be named as suitable polymers based on vinyl monomers. 25 Furthermore, the copolymers octylacrylamide / acrylates / butylaminoethyl-methacrylate copolymer, as commercially marketed under the trade names AMPHOMER® or LOVOCRYL® 47 by NATIONAL STARCH, or the copolymers of acrylates / octylacrylamides marketed under the trade names DERMACRYL® LT and DERMACRYL® 79 by NATIONAL STARCH are particularly suitable. 30 Suitable olefin-based polymers include homopolymers and copolymers of ethylene, propylene, butene, isoprene and butadiene. In another embodiment, the film-forming hydrophobic polymers may be the block copolymers comprising at least one block of styrene or the derivatives of styrene. These block copolymers can 35 be copolymers that contain one or more other blocks in addition to a styrene block, such as styrene / ethylene, styrene / ethylene / butylene, styrene / butylene, styrene / isoprene, styrene / butadiene. Such polymers are commercially distributed by BASF under the trade name “Luvitol® HSB”. In another embodiment, the film-forming polymers previously applied in the dyeing step may also be hydrophilic. 07 03 25 In another very particularly preferred embodiment, a method according to the invention is 5 characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic C-i-Cs alkoxysilane and / or a condensation product thereof, by application of at least one pigment and by application of at least one film-forming, hydrophilic polymer. 10 A hydrophilic polymer is understood to be a polymer that is soluble in water at 25°C (760mmHg) of more than 1% by weight, preferably more than 2% by weight. The water solubility of the film-forming, hydrophilic polymer can, for example, be determined in the following way,. 1.0g of the polymer is placed in a beaker. It is filled up to 100g with water. A magnetic 15 stir bar is added and the 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. A completely dissolved polymer appears macroscopically homogeneous. If the polymer-water mixture cannot be assessed visually due to a high turbidity of the mixture, the mixture is filtered. If no undissolved polymer remains on the filter paper, the solubility of the polymer is more than 1% by weight. 20 Non-ionic, anionic and cationic polymers can be used as film-forming, hydrophilic polymers. Suitable film-forming hydrophilic polymers can be selected, for example, from the group of polyvinylpyrrolidone (co)polymers, polyvinyl alcohol (co)polymers, vinylacetate (co)polymers, 25 carboxyvinyl (co)polymers, acrylic acid (co)polymers, methacrylic acid (co)polymers, natural gums, polysaccharides and / or acrylamide (co)polymers. Furthermore, it is particularly preferred to use polyvinylpyrrolidone (PVP) and / or a vinylpyrrolidonecontaining copolymer as film-forming hydrophilic polymer. 30 In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by application of at least one film-forming hydrophilic polymer selected from the group consisting of polyvinylpyrrolidone (PVP) and the copolymers of polyvinylpyrrolidone. 35 It is further preferred if the agent according to the invention contains polyvinylpyrrolidone (PVP) as the film-forming hydrophilic polymer. Particularly well-suited polyvinylpyrrolidones are available, for example, under the name Luviskol® K from BASF SE, especially Luviskol® K 90 or Luviskol® K 85 from BASF SE. 07 03 25 The polymer PVP K30, which is marketed by Ashland (ISP, POI Chemical), can also be used as another explicitly very well suited polyvinylpyrrolidone (PVP). PVP K 30 is a polyvinylpyrrolidone that is highly soluble in cold water and has the CAS number 9003-39-8. The molecular weight of PVP K 5 30 is about 40000g / mol. Other particularly suitable polyvinylpyrrolidones are the substances known under the trade names LUVITEC® K 17, LUVITEC® K 30, LUVITEC®K60, LUVITEC® K 80, LUVITEC® K 85, LUVITEC® K 90 and LUVITEC® K 115 and available from BASF. 10 The use of film-forming hydrophilic polymers from the group of copolymers of polyvinylpyrrolidone has also led to particularly good results. Vinylpyrrolidonevinylester copolymers, such as those marketed under the trademark Luviskol® 15 (BASF), are particularly suitable film-forming hydrophilic polymers. Luviskol® VA 64 and Luviskol® VA 73, both vinylpyrrolidone / vinylacetate copolymers, are particularly preferred non-ionic polymers. Of the vinylpyrrolidone-containing copolymers, a styrene / VP copolymer and / or a vinylpyrrolidonevinylacetate copolymer and / or a VP / DMAPA acrylates copolymer and / or a VP / vinyl 20 caprolactam / DMAPA acrylates copolymer are particularly preferred in cosmetic compositions. Vinylpyrrolidone-vinyl acetate copolymers are marketed under the name Luviskol® VA by BASF SE. For example, a VP / Vinyl caprolactam / DMAPA acrylates copolymer is sold under the trade name Aquaflex® SF-40 by Ashland Inc. For example, a VP / DMAPA acrylates copolymer is marketed by 25 Ashland under the name Styleze CC-10 and is a highly preferred vinylpyrrolidone-containing copolymer. Other suitable copolymers of polyvinylpyrrolidone may also be those obtained by reacting N-vinylpyrrolidone with at least one further monomer from the group consisting of V-vinylformamide, 30 vinyl acetate, ethylene, propylene, acrylamide, vinylcaprolactam, vinylcaprolactone and / or vinyl alcohol. In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by 35 application of at least one film-forming hydrophilic polymer selected from the group consisting of polyvinylpyrrolidone (PVP), vinylpyrrolidone / vinyl acetate copolymers, vinylpyrrolidone / styrene copolymers, vinylpyrrolidone / ethylene copolymers, vinylpyrrolidone / propylene copolymers, vinylpyrrolidone / vinylcaprolactam copolymers, vinylpyrrolidone / vinylformamide copolymers and / or vinylpyrrolidone / vinyl alcohol copolymers. 07 03 25 Another suitable copolymer of vinylpyrrolidone is the polymer known under the INCI designation maltodextrin / VP copolymer. 5 Furthermore, intensively dyed keratin material, especially hair, could be re-dyed with very good results when a non-ionic, film-forming, hydrophilic polymer was used as the film-forming, hydrophilic polymer. In a first embodiment, it may be preferred if the keratin material has been dyed with at least one non-10 ionic, film-forming, hydrophilic polymer in the previous dyeing step. According to the invention, a non-ionic polymer is understood to be a polymer which in a protic solvent - such as water - under standard conditions does not carry structural units with permanent cationic or anionic groups, which must be compensated by counterions while maintaining electron 15 neutrality. Cationic groups include quaternized ammonium groups but not protonated amines. Anionic groups include carboxylic and sulphonic acid groups. The agents used for dyeing may contain, for example, as a non-ionic, film-forming, hydrophilic polymer, at least one polymer selected from the group consisting of 20 - Polyvinylpyrrolidone, - Copolymers of N-vinylpyrrolidone and vinyl esters of carboxylic acids having 2 to 18 carbon atoms, in particular of N-vinylpyrrolidone and vinyl acetate, - Copolymers of N-vinylpyrrolidone and N-vinylimidazole and methacrylamide, - Copolymers of N-vinylpyrrolidone and N-vinylimidazole and acrylamide, 25 - Copolymers of N-vinylpyrrolidone with N,N-di(Ci to C4)-alkylamino-(C2 to C4)-alkylacrylamide, If copolymers of N-vinylpyrrolidone and vinyl acetate are used, it is again preferable if the molar ratio of the structural units contained in the monomer N-vinylpyrrolidone to the structural units of the 30 polymer contained in the monomer vinyl acetate is in the range from 20:80 to 80:20, in particular from 30:70 to 60:40. Suitable copolymers of vinylpyrrolidone and vinylacetate are available, for example, under the trademarks Luviskol®VA 37, Luviskol®VA 55, Luviskol® VA 64 and Luviskol® VA 73 from BASF SE. 35 Another particularly preferred polymer is selected from the INCI designation VP / MethacrylamideA / inyl Imidazole Copolymer, which is available under the trade name Luviset® Clear from BASF SE. 07 03 25 Another very particularly preferred non-ionic, film-forming, hydrophilic polymer is a copolymer of N-vinylpyrrolidone and N,N-dimethylaminiopropylmethacrylamide, which is sold, for example, by ISP under the INCI designation VP / DMAPA Acrylates Copolymer, e.g. under the trade name Styleze® CC 10. 5 A cationic polymer of interest is the copolymer of N-vinylpyrrolidone, N-vinylcaprolactam, N-(3-dimethylaminopropyl)methacrylamide and 3-(methacryloylamino)propyl-lauryl- dimethylammoniumchloride (INCI designation): Polyquaternium-69), which is marketed, for example, under the trade name AquaStyle® 300 (28-32% by weight active substance in ethanol-water mixture, 10 molecular weight 350000) by ISP. Other suitable film-forming, hydrophilic polymers include Vinylpyrrolidone vinylimidazolium methochloride copolymers, as offered under the designations Luviquat® FC 370, FC 550 and the INCI designation Polyquaternium-16 as well as FC 905 and 15 HM 552, Vinylpyrrolidone-vinylcaprolactam-acrylate terpolymers, as they are commercially available with acrylic acid esters and acrylic acid amides as a third monomer component, for example under the name Aquaflex® SF 40. 20 Polyquaternium-11 is the reaction product of diethyl sulphate with a copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate. Suitable commercial products are available, for example, under the names Dehyquart® CC 11 and Luviquat® PQ 11 PN from BASF SE or Gafquat® 440, Gafquat® 734, Gafquat® 755 or Gafquat® 755N from Ashland Inc. 25 Polyquaternium-46 is the reaction product of vinylcaprolactam and vinylpyrrolidone with methylvinylimidazolium methosulfate and is available for example under the name Luviquat® Hold from BASF SE. Polyquaternium-46 is preferably used in an amount of 1 to 5% by weight - based on the total weight of the cosmetic composition. It particularly prefers to use polyquaternium-46 in 30 combination with a cationic guar compound. It is even highly preferred that polyquaternium-46 is used in combination with a cationic guar compound and polyquaternium-11. Suitable anionic film-forming, hydrophilic polymers can be, for example, acrylic acid polymers, which can be in non-crosslinked or crosslinked form. Corresponding products are sold commercially, for 35 example, under the trade names Carbopol 980, 981, 954, 2984 and 5984 by Lubrizol or under the names Synthalen M and Synthalen K by 3V Sigma (The Sun Chemicals, Inter Harz). Examples of suitable film-forming, hydrophilic polymers from the group of natural gums are xanthan gum, gellan gum, carob gum. 07 03 25 Examples of suitable film-forming hydrophilic polymers from the group of polysaccharides are hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl cellulose and carboxymethyl cellulose. Suitable film-forming, hydrophilic polymers from the group of acrylamides are, for example, polymers 5 which are produced starting from monomers of (meth)acrylamido-C1-C4-alkyl sulphonic acid or the salts thereof. Corresponding polymers may be selected from the polymers of polyacrylamidomethanesulfonic acid, polyacrylamidoethanesulfonic acid, polyacrylamidopropanesulfonic acid, poly2-acrylamido-2-methylpropanesulfonic acid, poly-2-methylacrylamido-2-methylpropanesulfonic acid and / or poly-2-methylacrylamido-n-butanesulfonic 10 acid. Preferred polymers of poly(meth)acrylamido-C1-C4-alkyl-sulphonic acids are crosslinked and at least 90% neutralised. These polymers can or cannot be cross-linked. 15 Cross-linked and fully or partially neutralised polymers of the poly-2-acrylamido-2-methylpropane sulfonic acid type are available under the INCI names “Ammonium Polyacrylamido-2-methyl-Propanesulphonates" or “Ammonium Polyacryldimethyltauramides”. Another preferred polymer of this type is the cross-linked poly-2-acrylamido-2-methyl-20 propanesulphonicacid polymer marketed by Clamant underthe trade name Hostacerin AMPS, which is partially neutralised with ammonia. In another very particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent is applied to keratin material which has been dyed by 25 application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof, by application of at least one pigment and by application of at least one film-forming, anionic polymer. In this context, the best results have been obtained when the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a 30 condensation product thereof, by application of at least one pigment and by application of at least one film-forming anionic polymer, said film-forming anionic polymer comprising at least one structural unit of formula (P-l) and at least one structural unit of formula (P-ll) * CH2—CH COOM -I * CH2—CH2 * (p-ii), where M represents a hydrogen atom or ammonium (NH4), sodium, potassium, ½ magnesium or ½ calcium. 07 03 25 If M represents a hydrogen atom, the structural unit of formula (P-l) is based on an acrylic acid unit. If M stands for an ammonium counterion, the structural unit of formula (P-l) is based on the 5 ammonium salt of acrylic acid. If M stands for a sodium counterion, the structural unit of formula (P-l) is based on the sodium salt of acrylic acid. If M stands for a potassium counterion, the structural unit of formula (P-l) is based on the potassium salt of acrylic acid. 10 If M stands for a half equivalent of a magnesium counterion, the structural unit of formula (P-l) is based on the magnesium salt of acrylic acid. If M stands for a half equivalent of a calcium counterion, the structural unit of formula (P-l) is based on the calcium salt of acrylic acid. 15 Application of the decolouring agent In the method according to the invention, the decolouring agent is applied to the dyed keratin material. Since the decolouring agent is applied to the dyed hair, the decolouring agent must be applied to the 20 keratin material after the application of the previously described dye. In other words, the decolouring agent is applied to the keratin material after the dye has been rinsed out and the keratin material has preferably been dried to accurately determine the colour result. 25 The exact time of application of the decolouring agent is determined by the user’s wish to remove the unwanted or no longer required colouration. For example, the decolouring agent can be applied to the dyed keratin material 12 to 24 hours after application of the dyeing agent. In a further embodiment, however, the user can also wear the coloured keratin materials, in particular the hair, for a period of several days to weeks until he decides to change the dye again or until the user wishes 30 to have his original hair colour back again. Aluminium salts (a) in the decolouring agent The decolouring agent is characterised by its content of at least one aluminium salt (a) as defined in claim 1. Aluminium salts are usually used as cosmetic antiperspirants. Their use for decolouring dyed 35 hair has not yet been described. Aluminium chlorohydrate is a mixture of salts consisting of aluminium, chlorine and hydroxide with the composition AlnCI(3n-m)(OH)m. Aluminium chlorohydrate has the CAS number 1327-41-9. 07 03 25 Alternative names for aluminium chlorohydrate are ACH, basic aluminium chloride, aluminium oxychloride and aluminium chlorohydrate. Aluminium chlorohydrate can, for example, be obtained commercially as a 50% solution in water from Aurat JSC (Yugochem). 5 Aluminium sesquichlorohydrate or aluminium sesquichlorohydrate (ASCH) has the CAS number 12042-91-0 and is alternatively known as dialuminium chloride pentahydroxide. The raw material can be purchased commercially under the trade name AASCH 3143 Activated Aluminium Sesqichlorohydrate, USP from Summit Research Labs, Inc (IMCD). 10 Aluminium chloride has the molecular formula AlCh and the CAS numbers 7446-70-0, 7784-13-6 (hexahydrate) and 10124-27-3 (hydrate). One manufacturer of aluminium chloride in cosmetic purity is BASF, for example. The hexahydrate of aluminium chloride (CAS No. 7784-13-6) can be purchased from Ceasar &Loretz GmbH, for example. 15 Aluminium zirconium chloride hydroxide glycine, which may also be referred to as ALUMINIUM ZIRCONIUM TETRACHLOROHYDREX GLY, has the CAS number 57158-29-9 and can be purchased under the trade name Ultra ZAG 88 L from Summit Research Labs, Inc (IMCD). Aluminium zirconium tetrachlorohydrate also has the CAS number 57158-29-9 and can be 20 purchased, for example, under the trade name GB400 in the form of an aqueous solution from Gillette. Zirconium chlorine glycine hydroxy aluminium complexes, which are also alternatively referred to as aluminium zirconium octachlorohydrex GLY, have the CAS number 90604-80-1. They can be 25 purchased commercially under the trade name AAZG 531 D from Elementis (Summit Reheis, formerly Summit Research formerly). A particularly good decolouring effect was achieved with aluminium salts (a) from the group of Aluminium chlorohydrate, aluminium sesquichlorohydrate, aluminium chloride, aluminium zirconium 30 trichlorohydrate and aluminium zirconium tetrachlorine hydrate. The use of these salts is therefore particularly preferred. In another particularly preferred embodiment, a method according to the invention is characterized in that the decolouring agent contains at least one aluminium salt (a) selected from the group 35 consisting of aluminium chlorohydrate, aluminium sesquichlorohydrate, aluminium chloride, aluminium zirconium trichlorohydrate and aluminium zirconium tetrachlorohydrate. The aluminium salt or salts are preferably used in certain quantities in the decolouring agent to achieve the optimum decolouring result. Therefore, good results were obtained when the decolouring 07 03 25 agent - based on the total weight of the decolouring agent - contained one or more aluminium salts (a) in a total amount of 1.0 to 70.0% by weight, preferably from 3.0 to 60.0% by weight, more preferably from 5.0 to 50% by weight, still more preferably from 7.0 to 40% by weight and most preferably from 9.0 to 28% by weight. 5 In another very particularly preferred embodiment, a method according to the invention is characterised in that the decolouring agent - based on the total weight of the decolouring agent -contains one or more aluminium salts (a) in a total amount of from 1.0 to 70.0% by weight, preferably from 3.0 to 60.0% by weight, more preferably from 5.0 to 50% by weight, still more preferably from 10 7.0 to 40% by weight and most preferably from 9.0 to 28% by weight. Solvent (b) and / or water in the decolouring agent To further improve the dye removal, the decolouring agent used in the method according to the invention may contain at least one solvent (b). 15 For the purposes of the invention, a solvent is an organic substance that is liquid at 25°C and can dissolve other substances by physical means. The solvent(s) (b) are different from water. Suitable solvents are, for example, ethanol, isopropanol, benzyl alcohol, phenoxyethanol, 2-20 phenylethanol, 1-pentanol, glycerol, 1,2-propylene glycol, 1,2-ethanediol, dipropylene glycol, N-octylpyrrolidone, methoxybutanol, ethyl diglycol, polyethylene glycol, 1,3-butanediol, 1,6-hexanediol, propylene carbonate and N,N-dimethyl-9-decenamide. The best results were obtained with ethanol, so the use of ethanol is particularly preferred. 25 In another very particularly preferred embodiment, a method according to the invention is characterised in that the decolouring agent comprises at least one solvent (b) other than water from the group consisting of ethanol, isopropanol, benzyl alcohol, phenoxyethanol, 2-phenylethanol, 1-pentanol, glycerol, 1,2-propylene glycol, 1,2-ethanediol, dipropylene glycol, N-octylpyrrolidone, methoxybutanol, ethyl diglycol, polyethylene glycol, 1,3-butanediol, 1,6-hexanediol, propylene 30 carbonate and N,N-dimethyl-9-decenamide, most preferably ethanol. Benzyl alcohol is alternatively known as phenyl methanol and has the CAS number 100-51-6. Ethanol has the CAS number 64-17-5. Phenoxyethanol has the CAS number 122-99-6. 35 2-phenylethanol is alternatively known as 2-phenylethyl alcohol and has the CAS number 60-12-8. Alternative names for 1-pentanol are pentan-1-ol, n-pentanol or amyl alcohol. 1-pentanol has the CAS number 71-41-0. Glycerol is alternatively known as 1,2,3-propanetriol and has the CAS number 56-81-5. 07 03 25 1,2-Propylene glycol is alternatively known as 1,2-propanediol and has the CAS numbers 57-55-6 [(RS)-1,2-dihydroxypropane], 4254-14-2 [(R)-1,2-dihydroxypropane] and 4254-15-3 [(S)-1,2-dihydroxypropane]. 5 Ethylene glycol is alternatively known as 1,2-ethanediol and has the CAS number 107-21-1. Isopropanol is alternatively known as 2-propanol and has the CAS number 67-63-0. The dipropylene glycols (or oxydipropanyls)form a group of substances derived from the glycol ether. 10 The technical product of the same name (in the singular) is a mixture of three structural isomers. A dipropylene glycol according to the invention is understood to mean 2,2'-oxydi-1-propanol (CAS number 108-61-2), 1,1'-oxydi-2-propanol (CAS number 110-98-5) and 2-(2-hydroxypropoxy)-1-propanol (CAS number 106-62-7). The use of one of these dipropylene glycols in the decolouring agent is encompassed by the present invention, as is the use of a mixture of second or all three of 15 the structural isomers. N-octylpyrrolidone is alternatively known as N-octyl-2-pyrrolidone orcaprilyl pyrrolidone and has the CAS number 2687-94-7. This solvent can be obtained commercially, for example, under the trade name Surfadone LP 100 from the company Ashland (formerly ISP Global). 20 Methoxybutanol can alternatively be referred to as 3-methoxy-1-butanol and has the CAS number 2517-43-3. The solvent can be purchased, for example, as methoxybutanol from Biesterfeld. The IUPAC name for ethyldiglycol is 2-(2-ethoxyethoxy)-ethanol, ethyldiglycol has the CAS number 111-90-0. 25 Polyethylene glycols within the meaning of the present invention are polymers which are liquid at room temperature (25°C) and have the general molecular formula C2nH4n+2On+i. The repeating unit of the linear polymer is (-CH2-CH2-O-), with a molar mass of about 44 g mor1 Chemically, it is a polyether. Particularly well-suited polyethylene glycols are the representatives with an average 30 molecular mass between 200g / mol and 400g / mol, which are non-volatile liquids at room temperature. 1,3-butandiol is alternatively known as butane-1,3-diol or 1,3-butylene glycol and has the CAS numbers 107-88-0 (Racemate), 6290-03-5 [(R)-1,3-butanediol] and 24621-61-2 [(S)-(+)-1,3-butanediol]. All stereoisomers of 1,3-butanediol are encompassed by the invention. 35 An alternative name for 1,6-hexanediol is 1,6-dihydroxyhexane. 1,6-Hexandiol has the CAS number 629-11-8. 07 03 25 Propylene carbonate is alternatively known as 4-methyl-1,3-dioxolan-2-on or as propylene glycol carbonate or as carbonic acid propylene glycol ester and has the CAS numbers 108-32-7 [(RS)-4-methyl-1,3-dioxolan-2-on], 51260-39-0 [(S)-4-methyl-1,3-dioxolan-2-on] and 16606-55-6 [(R)-4-methyl-1,3-dioxolan-2-on]. All stereoisomers of propylene carbonate are encompassed by the 5 invention. N,N-Dimethyl-9-decenamid has the CAS number 1356964-77-6. In order to further improve the decolouration results, the solvents are particularly preferably used in 10 certain quantity ranges in the decolouring agent according to the invention. Therefore, the decolouring agent may contain - based on the total weight of the decolouring agent - one or more solvents (b) other than water in a total amount of from 3 to 95% by weight, preferably from 5 to 85% by weight, more preferably from 10 to 75% by weight, still more preferably from 15 to 65% by weight and most preferably from 20 to 55% by weight. 15 In a further particularly preferred embodiment, a method according to the invention is characterised in that the decolouring agent - based on the total weight of the decolouring agent - contains one or more solvents (b) other than water in a total amount of from 3 to 95% by weight, preferably from 5 to 85% by weight, more preferably from 10 to 75% by weight, still more preferably from 15 to 65% by 20 weight and most preferably from 20 to 55% by weight. In another very particularly preferred embodiment, a method according to the invention is characterised in that the decolouring agent - based on the total weight of the decolouring agent -contains 3 to 95% by weight, preferably 5 to 85% by weight, more preferably 10 to 75% by weight, 25 still more preferably 15 to 65% by weight and very particularly preferably 20 to 55% by weight of ethanol. The presence of water in the decolouring agent was also able to further improve the dye removal of the film comprising Ci-Ce alkoxysilanes and pigments on the keratin material. It has been found to 30 be preferable if the decolouring agent - based on the total weight of the decolouring agent - contained 1 to 95% by weight, preferably 10 to 85% by weight, more preferably 20 to 75% by weight, still more preferably 20 to 65% by weight and most preferably 30 to 55% by weight of water. In a further particularly preferred embodiment, a method according to the invention is characterised 35 in that the decolouring agent - based on the total weight of the decolouring agent - contains 1 to 95% by weight, preferably 10 to 85% by weight, more preferably 20 to 75% by weight, still more preferably 20 to 65% by weight and most preferably 30 to 55% by weight of water. 07 03 25 The results were particularly good when the decolouring agent used in the method according to the invention - based on the total weight of the decolouring agent - was - 9.0 to 28% by weight of aluminium salt(s) (a), and - 20 to 55% by weight of ethanol (b) and - 30 to 55% by weight of water. It is understood that the sum of the weight percentages of aluminium salt(s) (a), solvent(s) (or ethanol) (b) and water cannot exceed 100% by weight. pH values of the decolouring agent Further tests have shown that the pH values of the decolouring agent have an influence on its decolouring performance. The best results were obtained when the decolouring agent was adjusted to pH values in the range from 1.5 to 7.5, preferably from 1.5 to 6.0, more preferably from 1.5 to 5.0 and most preferably from 1.5 to 4.5. In another particularly preferred embodiment, a method according to the invention is characterised in that the decolouring agent has a pH value of 1.5 to 7.5, preferably 1.5 to 6.0, more preferably 1.5 to 5.0 and most preferably 1.5 to 4.5. The pH values can be measured using the usual methods known from the prior art, such as measurement by means of glass electrodes via combination electrodes or via pH indicator paper. The pH values for the purposes of the present invention are pH values measured at a temperature of 22°C. The pH value is preferably adjusted using acidifying agents and alkalizing agents suitable for use in cosmetics and known from the prior art. Other cosmetic ingredients in the decolouring agent The decolouring agents may also contain other active ingredients, auxiliaries and additives, such as structurants such as glucose, maleic acid and lactic acid, hair-conditioning compounds such as phospholipids, for example lecithin and cephalins; perfume oils, dimethylisosorbide and cyclodextrins; polymers such as anionic, non-ionic and cationic polymers; surfactants such as anionic, non-ionic, cationic, zwitterionic and amphoteric surfactants, fat components, fibre structureimproving active ingredients, in particular monosaccharides, disaccharides and oligosaccharides such as glucose, galactose, fructose, fruitsugar and lactose; anti-dandruff agents such as piroctone olamine, zinc omadine and climbazole; amino acids and oligopeptides; protein hydrolysates on an animal and / or vegetable basis, as well as in the form of their fatty acid condensation products or, if applicable, anionically or cationically modified derivatives; vegetable oils; light stabilisers and UV blockers; active ingredients such as panthenol, pantothenic acid, pantolactone, allantoin, 49 07 03 25 pyrrolidinone carboxylic acids and their salts as well as bisabolol; in particular hydroxycinnamic acids, hydroxybenzoic acids, 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, 5 carbonates, hydrogen carbonates, guanidines, ureas as well as primary, secondary and tertiary phosphates; opacifiers such as latex, styrene / PVP and styrene / acrylamide copolymers; pearlescent agents such as ethylene glycol monostereate and distearate and PEG-3-distearate; and propellants such as propane-butane mixtures, N2O, dimethyl ether, CO2 and air. 10 The selection of these other substances will be made by the specialist according to the desired properties of the agents. With regard to other optional components and the quantities of these components used, explicit reference is made to the relevant manuals known to the specialist. The additional active ingredients and auxiliary substances are preferably used in the preparations according to the invention in quantities of 0.0001 to 25% by weight each, in particular 0.0005 to 15% 15 by weight, based on the total weight of the respective agent. As the agents are decolouring agents, they preferably do not contain any direct dyes, oxidation dye precursors, pigments or natural dyes. 20 Preferably, the decolouring agent does not contain any direct dyes. Preferably, the decolouring agent does not contain any oxidation dye precursors. Preferably, the decolouring agent does not contain any pigment. 25 Preferably, the decolouring agent does not contain any natural dyes. Application of the decolouring agent In the method according to the invention, the previously described decolouring agent is applied to 30 the dyed keratin material. Preferably, the decolouring agent is left to act for a certain time and then rinsed off again. The application can be done by hand or with the help of an applicator, such as a brush or an aplicette, or even a bristle brush or a comb. 35 Depending on whether the user wants a complete decolouration or only certain areas or parts and / or strands are to be decolorized, the decolouring agent can be applied either to the entire keratinous material (such as the entire head of hair) or to specific parts or corresponding strands of the keratinous material or keratinous fibres. 07 03 25 After application, the decolouring agent is left to act on the keratin material for a certain period of time. For example, the application time may be from 5 to 60 minutes, preferably from 5 to 50 minutes, more preferably from 5 to 40 minutes, and most preferably from 5 to 30 minutes. After this application 5 time, the decolouring agent is preferably rinsed out again with water In a further preferred embodiment, a method according to the invention is characterised in that the decolouring agent is applied to the dyed keratin material and rinsed off again after an application time, preferably after an application time of 3 to 30 minutes, particularly preferably of 5 to 20 minutes. 10 The decolouring agent can be applied to the keratin material at room temperature or at body temperature. To support or accelerate the dye removal, however, the keratin material to which the decolouring agent has been applied can also be exposed to elevated temperatures. It is in accordance with the invention if the decolouring agent is applied to the dyed keratin material and the 15 keratin material is heated to a temperature of 25 to 70°C, preferably 25 to 60°C, more preferably 30 to 55°C and most preferably 40 to 55°C during application of the decolouring agent. In a further embodiment, a method according to the invention is characterised in that -the decolouring agent is applied to the dyed keratin material -the keratin material is heated to a temperature of from 25 to 70°C, preferably from 25 to 60°C, more 20 preferably from 30 to 55°C and most preferably from 40 to 55°C during the application of the decolouring agent, and then -the decolouring agent is rinsed off again. In addition to providing thermal support for the decolouration process, it is also possible to subject 25 the keratin material to which the decolouring agent has been applied to mechanical stress in order to improve the detachment of the film formed on the keratin material during dyeing. For example, the keratin material can be massaged with the hands or combed with a comb or brush during the decolouration process. Any other mechanical stress suitable for improving the detachment of the dyed film from the keratin material under the application of the decolouring agent is also conceivable 30 and encompassed by the method according to the invention. In the context of a further preferred embodiment, a method according to the invention is characterized in that - the decolouring agent is applied to the dyed keratin material, 35 - the keratin material is combed, massaged, brushed or otherwise subjected to mechanical force during the application of the decolouring agent, and then -the decolouring agent is rinsed off again. 07 03 25 As previously described, the decolouring agent according to the invention can be applied to decolourise keratin material that has been dyed by applying at least one organosilicon compound and at least one pigment. If, for example, the user notices after dyeing that the colour result does not meet their requirements, they can take this as an opportunity to remove the dye by applying the 5 decolouring agent again. Furthermore, the user can also plan dyeing and subsequent decolouration from the outset, for example, if he wants to dye his hair for a particular occasion and then decolorize it again. For this purpose, the user can also be provided with all the agents or formulations necessary for both 10 colouration and decolouration. Thus, a second object of the present invention is a method for dyeing and later decolouring human hair, comprising the following steps: (1) Applying a dye to the hair, the dye comprising one or more organic Ci-Ce alkoxysilanes 15 and / or condensation products thereof, and one or more pigments, (2) Allow the dye to act on the hair, (3) Rinse the dye from the hair, (4) Applying a decolouring agent, as disclosed in detail in the description of the first subject matter of the invention, to the hair, 20 (5) Allow the decolouring agent to act on the hair and (6) Rinsing the decolouring agent out of the hair. In a further preferred embodiment, a corresponding method also comprises (1) applying a colouring agent to the hair, wherein the colouring agent comprises one or 25 more organic Ci-Cb alkoxysilanes and / or condensation products thereof, one or more pigments and one or more film-forming polymers. The organic Ci-Ce alkoxysilanes and / or their condensation products have already been disclosed in detail in the description of the first subject matter of the invention. The pigments have already been 30 disclosed in detail in the description of the first subject matter of the invention. The decolouring agent has also already been disclosed in detail in the description of the first subject matter of the invention. Multi-component packaging unit and use It is particularly convenient for the user if the appropriate dyeing and decolouring agents are made 35 available to him in the form of a multi-component packaging unit. Thus, another object of the present invention is to provide a multi-component packaging unit (kit-of-parts) for dyeing and decolouring keratin material, comprising separately prepared: 07 03 25 - a first container with an agent containing one or more organic Ci-Ce alkoxysilanes and / or their condensation products, - a second container with an agent containing at least one pigment, - a third container containing a decolouring agent as disclosed in detail in the description of the first 5 object of the invention. A further object of the invention is the use of a decolouring agent, as disclosed in detail in the description of the first object of the invention, for decolouring dyed keratinous material, preferably for decolouring keratinous material which has been dyed by applying at least one organosilicon 10 compound and at least one pigment. Particularly preferred is the use of the decolouring agent for decolouring keratinous material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof and by application of at least one pigment. 15 The organic Ci-Ce alkoxysilanes and / or their condensation products have already been disclosed in detail in the description of the first subject matter of the invention. The pigments have already been disclosed in detail in the description of the first subject matter of the invention. The decolouring agent has also already been disclosed in detail in the description of the first subject matter of the invention. 20 Concerning the further preferred embodiments of the multicomponent packaging unit according to the invention and the use, mutatis mutandis what has been said about the methods according to the invention applies. 25 Examples 1. Preparation of a mixture of organic C-i-Ce alkoxysiloxanes or their condensation products In a 500 ml round bottom flask, 23.4g ethanol (abs.) and 52.6g methyltriethoxysilane and 17.5g (3-aminopropyl)triethoxysilane were mixed together by stirring. This mixture was heated to 50°C by 5 further stirring. Then 6.4g of a 1% solution of sodium hydroxide in water was added over a period of approx. 5 minutes. The temperature of the reaction mixture rose to 59°C and dropped to 55°C after the addition was completed. The mixture was stirred for a further 45 minutes at 50°C and then filled into an airtight glass container. 10 2. Preparation of a dye with pigments The following dyes were produced 07 03 25 F1 (% by weight) F2 (% by weight) F3 (% by weight) F4 (% by weight) Pigment Unipure Red LC 3079 (Cl 15850) 1.0 — — — Pigment Unipure Blue LC 689 Cl 77510 (Ferric Ammonium Ferrocyanide) —. 1.0 — Pigment Blue 60 (Cl 69800) — — 1.0 — Pigment Yellow 1 (Cl 11680) — — — 1.0 Polyethylene Glycol MG 400 ad 100 ad 100 ad 100 ad 100 3. Preparation of the readv-to-use dye 15 To prepare the ready-to-use dye, 1.0g of the mixture of organic C-i-Ce alkoxysiloxanes prepared under point 1 was mixed with 10g each of the pigment dye prepared under point 2. Ready-to-use dye AWM-F1 (% by weight) AWM-F2 (% by weight) AWM-F3 (% by weight) AWM-F4 (% by weight) Mixture of organic Ci-Ce alkoxysiloxanes ig 1g ig 1g Dyes 10g F1 10g F2 10g F3 10g F4 4. Preparation of a post-treatment agent 20 The following post-treatment agent was prepared. Post-treatment agent % by weight Water 99.0 Keltrol® CG-SFT (Xanthan) 1.0 07 03 25 5. Dyeing Strands of hair (Kerling natural white) were moistened under running water and then rubbed dry with a towel for 30 seconds. 5 The ready-to-use dye was then applied to a towel-dried strand of hair (0.4g of product (a) per strand). The product was massaged into each strand of hair for 30 seconds. Immediately afterwards, the post-treatment agent was applied to the hair strands (1.0g post-treatment agent per hair strand). Each strand of hair was massaged again for 30 seconds so that a mixture of the ready-to-use dye 10 and the after-treatment agent was formed. This mixture was left to work for a further minute and then rinsed out with water. The strands were dried. The colour result of the dyed strands was assessed visually under a daylight lamp. The strands were then stored at room temperature for 2 days. 15 6. Decolouration The following decolouring agents were prepared. Decolouring agent E1 (% by weight) E2 (% by weight) E3 (% by weight) E4 (% by weight) Citric acid — ad pH 3 — — Aluminium chlorohydrate (ACH) — — 25 25 Aluminium zirconium tetrachlorine hydrate (AZG) — — — — Aluminium chloride (AlCh) — — — — Aluminium sesquichlorohydrate (ASCH) — — — — Sodium chloride — — — — Ethanol (96%) 100 50 — 25 Water (dist.) — 50 75 50 Decolouring agent E5 (% by weight) E6 (% by weight) E7 (% by weight) E8 (% by weight) Citric acid — — — — Aluminium chlorohydrate (ACH) 10 — — — Aluminium zirconium tetrachlorine hydrate (AAZG) — 10 — — Aluminium chloride (AlCb) — — 10 — Aluminium sesquichlorohydrate (ASCH) — — — 10 Sodium chloride — — — — Ethanol (96%) 45 45 45 45 Water (dist.) 45 45 45 45 07 03 25 Decolouring agent E9 (% by weight) E10 (% by weight) E11 (% by weight) E12 (% by weight) Citric acid — — — — Aluminium chlorohydrate (ACH) — — — — Aluminium zirconium tetrachlorine hydrate (AAZG) — — — — Aluminium chloride (AlCb) — — — — Aluminium sesquichlorohydrate (ASCH) 15 20 25 — Sodium chloride — — — 10 Ethanol (96%) 42.5 40.0 37.5 45.0 Water (dist.) 42.5 40.0 37.5 45.0 One of the decolouring agents was applied to each of the strands dyed under point 5 (1g of decolouring agent per strand), massaged in well and left to work for 10 minutes. Each strand was 5 then rinsed with water for 30 seconds. This process was repeated twice. The strands were then dried and visually assessed again under the daylight lamp. 7. Results 7.1. Dyeing with AWM-F1 (red, pigment Unipure Red LC 3079 (Cl 15850)) 10 Decolouration with E1, E2, E3 and E4 directly after dyeing E1 (ethanol) E2 (ethanol / water) E3 (ACH / water) E4 (ACH / water / EtOH) +++ ++ + + + - intense red red red-orange pale red natural white / undyed Colour intensity: - undyed + low ++ medium +++ high Good to very good decolouration was achieved with decolouring agents E3 and E4. The best decolouring effect was shown by decolouring agents E4. 7.2. Dyeing with AWM-F1 (red, pigment Unipure Red LC 3079 (Cl 15850¾¾ Decolouration with E5, E5, E7 and E8 directly after dyeing E5 ACH in water / EtOH E6 AAZGin water / EtOH E7 AICI3 in water / EtOH E8 ASCH in water / EtOH +++ - + + - intense red natural white / undyed pale red pale red natural white / undyed Good to very good decolouration was achieved with decolouring agents E5 to E8. Decolouring 5 agents E5 and E8 showed the best decolouring effect. 7.3. Dyeing with AWM-F1 (red, pigment Unipure Red LC 3079 (Cl 15850¾¾ 07 03 25 Decolouration with E8, E9, E10, E11 and E12 directly after dyeing E8 ASCH 10% E9 ASCH 15% E10 ASCH 20% E11 ASCH 25% E12 NaCI 10% +++ intense red natural white undyed natural white undyed natural white undyed natural white undyed ++ medium-red 10 Very good decolouration was achieved with decolouring agents E8 to E11. Decolouring agent E12 with 10% by weight sodium chloride, which is not according to the invention, showed poor decolouration. 15 7.4. Decolouration with AWM-F2 (Pigment Unipure Blue LC 689 Cl 77510 (Ferric Ammonium Ferrocyanide) Decolouration with E8, E9, E10, E11 and E12 directly after dyeing E8 ASCH 10% E9 ASCH 15% E10 ASCH 20% E11 ASCH 25% E12 NaCI 10% +++ intense blue ++ medium blue ++ medium blue + pale blue + pale blue +++ intense blue The dyes obtained with the blue pigment Cl 77510 were generally more difficult to decolourise than 20 the dyes obtained with the red pigment Cl 15850. Good decolouration was achieved with decolouring agents E8 to E11. Decolouring agent E12 with 10% by weight sodium chloride, which is not according to the invention, did not show any decolouration. 7.5. Decolouration of various pigment dyes Decolouration with decolouring agent E4 (ACH / water / EtOH) ready-to-use dye directly after dyeing after decolouration AWM-F1 +++ intense red natural white / undyed AWM-F2 +++ intense blue + pale blue AWM-F3 +++ intense blue + pale blue AWM-F4 +++ intense yellow + pale yellow All pigment dyes could be decoloured with decolouring agent E4. 07 03 25

Claims

07 03 251. Method for decolouring keratinous material which has been dyed by the application of at least one organosilicon compound and at least one pigment, wherein a decolouring agent containing (a) at least one aluminium salt selected from aluminium chlorohydrate, aluminium sesquichlorohydrate, aluminium chloride, aluminium dichlorohydrate, aluminium hydroxide, potassium aluminium sulphate, aluminium bromohydrate, aluminium sulphate, aluminium chlorohydrex propylene glycol, aluminium chlorohydrex polyethylene glycol, aluminiumpropylene glycol complexes, aluminium sesquichlorohydrex propylene glycol, aluminium sesqui-chlorohydrex polyethylene glycol, aluminium propylene glycol-dichlorohydrex, Aluminiumpolyethylene glycol-dichlorohydrex, aluminium undecylenoyl collagen amino acid, sodium aluminium lactate, sodium aluminium chlorohydroxy lactate, aluminium lipoamino acids, aluminium lactate, aluminium chlorohydroxyallantoinate, sodium aluminium chlorohydroxy lactate, aluminium zirconium trichlorohydrate, aluminium zirconium tetrachlorohydrate, aluminium zirconium pentachlorohydrate, aluminium zirconium octachlorohydrate, aluminium-zirconium-propylene glycol complexes, aluminium-zirconium trichlorohydrexglycine, aluminiumzirconium tetrachlorohydrexglycine, aluminium-zirconium pentachlorohydrexglycine, aluminiumzirconium octachlorohydrexglycine, and mixtures thereof, is applied to the coloured keratin material.

2. Method according to Claim 1, characterised in that the decolouring agent is applied to keratin material which has been dyed by application of at least one organic Ci-Ce alkoxysilane and / or a condensation product thereof and by application of at least one pigment.

3. Method according to Claims 1 or 2, characterised in that the decolouring agent contains at least one aluminium salt (a) which is selected from the group consisting of Aluminium chlorohydrate, aluminium sesquichlorohydrate, aluminium chloride, aluminium zirconium trichlorohydrate, aluminium zirconium tetrachlorine hydrate, and mixtures thereof.

4. Method according to any one of Claims 1 to 3, characterised in that the decolouring agent - based on the total weight of the decolouring agent - contains one or more aluminium salts (a) in a total amount of 1.0 to 70.0% by weight.

5. Method according to any one of Claims 1 to 3, characterised in that the decolouring agent - based on the total weight of the decolouring agent - contains one or more aluminium salts (a) in a total amount of from 3.0 to 60.0% by weight.

6. Method according to any one of Claims 1 to 3, characterised in that the decolouring agent - based on the total weight of the decolouring agent - contains one or more aluminium salts (a) in a total amount of from 5.0 to 50% by weight.07 03 257. Method according to any one of Claims 1 to 3, characterised in that the decolouring agent - basedon the total weight of the decolouring agent - contains one or more aluminium salts (a) in a total amount of from 7.0 to 40% by weight.

8. Method according to any one of Claims 1 to 3, characterised in that the decolouring agent - based on the total weight of the decolouring agent - contains one or more aluminium salts (a) in a total amount of from 9.0 to 28% by weight.

9. Method according to any one of Claims 1 to 8, characterised in that the decolouring agent comprises at least one solvent (b) other than water from the group consisting of ethanol, isopropanol, benzyl alcohol, phenoxyethanol, 2-phenylethanol, 1-pentanol, glycerol, 1,2-propylene glycol, 1,2-ethanediol, dipropylene glycol, N-octylpyrrolidone, methoxybutanol, ethyl diglycol, polyethylene glycol, 1,3-butanediol, 1,6-hexanediol, propylene carbonate and N,N-dimethyl-9-decenamide.

10. Method according to claim 9, wherein the at least one solvent b) comprises ethanol.

11. Method according to any one of Claims 1 to 10, characterised in that the decolourising agentcontains - based on the total weight of the decolourising agent - one or more solvents (b) other than water in a total amount of 3 to 95% by weight.

12. Method according to any one of Claims 1 to 10, characterised in that the decolourising agent contains - based on the total weight of the decolourising agent - one or more solvents (b) other than water in a total amount of 5 to 85% by weight.

13. Method according to any one of Claims 1 to 10, characterised in that the decolourising agent contains - based on the total weight of the decolourising agent - one or more solvents (b) other than water in a total amount of 10 to 75% by weight.

14. Method according to any one of Claims 1 to 10, characterised in that the decolourising agent contains - based on the total weight of the decolourising agent - one or more solvents (b) other than water in a total amount of 15 to 65% by weight.

15. Method according to any one of Claims 1 to 10, characterised in that the decolourising agent contains - based on the total weight of the decolourising agent - one or more solvents (b) other than water in a total amount of 20 to 55% by weight.

16. Method according to any one of Claims 1 to 15, characterised in that the decolouring agent contains - based on the total weight of the decolouring agent -1 to 95% by weight of water,07 03 2517. Method according to any one of Claims 1 to 15, characterised in that the decolouring agent contains - based on the total weight of the decolouring agent -10 to 85% by weight of water.

18. Method according to any one of Claims 1 to 15, characterised in that the decolouring agent contains - based on the total weight of the decolouring agent - 20 to 75% by weight of water.

19. Method according to any one of Claims 1 to 15, characterised in that the decolouring agent contains - based on the total weight of the decolouring agent - 20 to 65% by weight of water.

20. Method according to any one of Claims 1 to 15, characterised in that the decolouring agent contains - based on the total weight of the decolouring agent - 30 to 55% by weight of water.

21. Method according to any one of Claims 1 to 20, characterised in that the decolouring agent is applied to the dyed keratin material and rinsed off again after an application time.

22. Method according to claim 21, wherein the decolouring agent is applied to the dyed keratin material and rinsed off again after an application time of 3 to 30 minutes.

23. Method according to claim 21, wherein the decolouring agent is applied to the dyed keratin material and rinsed off again of 5 to 20 minutes.