FR3024646A1 - HAIR STAINING AND WASHING PROCESS AND DEDICATED KIT - Google Patents

Abstract

The object of the invention is an exothermic hair-dyeing and shaping process, comprising at least the following steps in the order of: a) applying to hair, a hair dye composition having an alkaline pH of at least 7.1, and leave the composition at least 10 minutes on the hair b) apply on the hair a hair smoothing composition having an acid pH of less than 6.9, and leave the composition at least 10 minutes on the hair hair c) drying the hair and / or pass a straightening iron, steps a) and b) being carried out successively without rinsing. The invention also relates to a hair coloring and smoothing kit for the implementation of this method.

Description

The present invention relates to a method for coloring and smoothing hair, and a kit for carrying out this method. Hairdressers are often asked to perform a smoothing and coloring on the hair of their customers.

There are different types of coloring: hair dyes are classified as "permanent", "semi-permanent" or "temporary". For permanent and semi-permanent dyes, oxidation dyes are generally used, and for direct dyeing direct dyes are used. The oxidation dyes are formed from low molecular weight intermediates that are known as "precursors" and "couplers". These molecules are small enough to penetrate the hair. By the action of an oxidizing agent such as hydrogen peroxide in an alkaline medium, the precursor is oxidized and reacts with the coupler, thereby forming the dye molecule. Typically, the oxidation dyeing composition comprises ammonia or preferably sodium hydroxide as the alkalizing agent, so as to obtain an opening of the hair scales and thereby improve the penetration of the precursor and the coupler. By the action of the oxidizing agent, the intermediate compounds are coupled to the interior of the hair. Since the size of the dye molecule thus formed is greater than the size of the intermediate products, the dye molecule remains trapped inside the hair, so that permanent coloring can be achieved. Hair straightening is intended to smooth curly or frizzy hair. It usually involves the use of straighteners. The high temperature of the straightening iron leads to a breakdown of the hydrogen bonds of the keratin of the hair but with the humidity, the hydrogen bonds are formed again, and the hair returns to their original form quickly. To extend the duration of maintenance of hair smoothing, products have been developed. Their action is based on the cleavage of the disulfide bonds connecting two cysteine molecules of hair keratin. This cleavage is generally by the action of a sulphide or thio group containing a reducing agent. After the hair has been positioned in the desired shape, new disulfide bonds are formed by application of an oxidizing agent such as hydrogen peroxide, thereby fixing the shape of the hair. Glyoxylic acid, known as a buffering agent in cosmetic compositions, may also cause smoothing if used in combination with heat input. The hair is then smoothed sustainably for several washing cycles. Currently, hairdressers rarely achieve during the same salon visit both a smoothing and hair coloring of their customers. It is indeed generally advisable to carry out the smoothing, then one to two weeks later to perform the coloring, which is very restrictive and expensive in terms of time. When a hairdresser desires to even perform a hair coloring and smoothing successively, it implements the following process: Application of an alkaline shampoo to open the scales of the hair and allow the intimate penetration of the product smoothing , 15 Application of the smoothing product with a pause time, Drying of the hair by the dryer, Smoothing by heating plates Rinsing the hair Applying a mask to rebalance the pH and rehydrate the hair 20 Rinse Drying Application on dry hair dye dye for hair, respecting a break time, Applying a shampoo, 25 Drying hair. This protocol is extremely long and the results obtained are unsatisfactory, in particular because of the acid pH of the smoothing product and its chemical reactivity which cause discolouration, in particular lightening of the hue. The colors are faded quickly so that the dyed hair quickly loses its brightness and intensity. To solve this problem, a method has been proposed in application WO2014 / 068102 which consists in inverting the application of the coloring product and the smoothing product, but this method is also not suitable and adapted, and is not implemented in hairdressing salons, because it is long and the results obtained are still unsatisfactory especially with regard to hair coloring. In addition, this method, because of its length and complexity, can not be performed by non-professionals.

The object of the present invention is to overcome the drawbacks of the existing processes and to propose a method and products for its implementation, making it possible to achieve, in a minimum of time, both smoothing and coloring of the hair with impeccable and surprising results in terms of smoothing and color obtained, and a very good performance of these effects over time.

For this purpose, the invention is directed to an exothermic hair dyeing and smoothing method, comprising at least the following steps in the order of: a) applying to a hair a hair dye composition having an alkaline pH of at least 7.1, and leave the composition at least 10 minutes on the hair, 15 - b) applying to the hair a hair smoothing composition having an acidic pH of less than 6.9, and leaving the composition at minus 10 minutes on the hair, c) drying the hair and / or passing a straightener, the steps a) and b) being carried out successively without rinsing.

Advantageously, this method can be carried out in a reduced number of steps in comparison with the methods of the prior art, while making it possible to obtain a smoothing and a successful coloration that meets the expectations of the users. It can be implemented by both hairdressing professionals and non-professional individuals. The invention also relates to a hair coloring and smoothing kit for carrying out a method according to one of the preceding claims, characterized in that it comprises: a dyeing composition for the hair having an alkaline pH of at least 7.1; a hair smoothing composition having an acidic pH of less than 6.9; a user's leaflet incorporating the steps of the method according to one of the preceding claims. Other features and advantages will become apparent from the detailed description of the invention which follows.

According to a first aspect, the invention therefore relates to a method for coloring and smoothing comprising at least the following steps in the order of: a) applying to hair, a dye composition for hair having an alkaline pH of at least 7.1, and leave the composition at least 10 minutes on the hair; b) apply to the hair a hair smoothing composition having an acidic pH of less than 6.9, and leave the composition at least 10 minutes; minutes on the hair - c) drying the hair and / or passing a straightening iron, the steps a) and b) being carried out successively without rinsing. The pH values are the values measured at room temperature, 20 ° C. The process according to the invention is exothermic. The exothermic reaction is caused by the subsequent rinse-free application of the alkaline coloring composition and the smoothing acid composition.

The heat released plays an important role in accelerating the smoothing reaction. In addition, the neutralization of the alkaline pH of the staining preparation by the smoothing preparation allows the hair to approach the physiological pH. The pH variation caused allows the scales of the hair to close and effectively trap the coloring molecules thus allowing better staining over time. The method according to the invention thus makes it possible to obtain semipermanent coloration and smoothing of the hair in a single application protocol without delay between the coloring and smoothing operation. The quality of the hair is not deteriorated, the coloring is of better quality and the duration of the smoothing effect is improved.

Step a) of the method comprises applying to hair, a dye composition or hair coloring composition having an alkaline pH of at least 7.1, and leaving the composition at least 10 minutes on the hair. Preferably, the dyeing composition for the hair has a pH of between 7.1 and 11, more preferably between 8 and 11.

It may be any coloring composition having a basic pH. Conventionally, this composition comprises at least one dye, in particular: at least one direct dye and / or at least one oxidation dye precursor and at least one coupler. The staining composition may also comprise: at least one alkalinizing agent and / or at least one oxidizing agent for the hair.

It may also include other additives and excipients, especially surfactants. The coloring composition may be in any form suitable for application to the hair, in particular emulsion, cream, paste and foam. If the composition contains a direct dye, any direct dye suitable for hair dyeing may be used. In particular, direct dyes may include an anionic dye, a nitro dye, a disperse dye, a cationic dye, or a mixture thereof. Non-limiting examples of the cationic dyes are base Blue 6, Blue 7, Blue 9, Basic Blue 26, Basic Blue 41, Basic Blue 99, Basic Brown 4, Basic Brown 16, Basic Brown 17, Natural Brown 7, Basic Green 1, Orange 31 Base, Red 2 15 Basic, Basic Red 12, Basic Red 22, Basic Red 51, Basic Red 76, Basic Violet 1, Basic Purple 2, Basic Purple 3, Basic Purple 10, Basic Purple 14, Basic Yellow 57 and Base Yellow 87 and mixtures thereof. Particularly preferred are Basic Red 51, Basic Orange 31, Basic Yellow 87 and mixtures thereof. Non-limiting examples of anionic dyes are Acid Black 1, Acid Blue 1, Acid Blue 20 3, Blue Food 5, Acid Blue 7, Acid Blue 9, Acid Blue 74, Acid Orange 3, Orange Acid 6, Orange Acid 7 , Orange Acid 10, Acid Red 1, Acid Red 14, Acid Red 18, Acid Red 27, Acid Red 50, Acid Red 52, Acid Red 73, Acid Red 87 Acid Red 88, Acid Red 92, Acid Red 155, Acid Red 180, Acid Violet 9, Acid Violet 43, Acid Violet 49, Acid Yellow 1, Acid Yellow 23, Acid Yellow 3, Yellow Food No. 8, D & C Brown No. 1, D & C Green No. 5, D & C Green No. 8, D & C Orange No. 4, D & C Orange No. 10, D & C Orange No. 11, D & C Red No. 21, D & C Red No. 27, D & C Red No. 33, D & C Violet 2, D & C Yellow No. 7, D & C Yellow No. 8, Yellow D & C No. 2, FD & C Red 2, FD & C Red 40, Red FD & C No. 4, FD & C Yellow No. 6, FD & C Blue 1, Food Black 1, Food Black 2, Disperse Black 9 and Disperse Violet 1 and their alkali metal salts such as sodium or potassium salt and mixtures thereof.

Of these, the preferred anionic dyes are Acid Red 52, Acid Violet 2, Acid Red 33, Acid Orange 4, 27-Red acid and Yellow 10 acid and their salts.

The most preferred anionic dyes are Acid Red 52, Acid Violet 2, Acid Red 33, Acid Orange 4 and Acid Yellow 10 and their salts and mixtures thereof. Non-limiting examples for the nitro dye are HC blue No. 2, No. 4 HC blue, HC Blue No. 0.5, HC blue No. 6, HC Blue No. 0.7, HC blue No. 8, No. ° 9 HC Blue, HC Blue No.10, 5 No.11 HC Blue, Blue HC No.12, No.13 HC Blue, HC Brown No. 1, HC Brown None 0.2, HC Green Not .1, HC Orange None 0.1, HC Orange None 0.2, HC orange No 0.3, HC orange No.5, HC Red BN, HC Red No. 1, HC Red None 0.3, HC Red No. 7, HC Red No. 0.8, HC Red No. 9, HC Red No. 10, HC Red No. 11, HC Red No. 13, HC Red No. 54, No. 14 HC Red, Violet HC BS, HC Violet No. .l, HC Violet No. 2, HC Yellow No. 0.2, HC Yellow No. 0.4, HC Yellow No. 5, HC Yellow No. 6, HC Yellow No. 7, HC Yellow No. 8, HC Yellow No. 9, HC Yellow No. 10, No. 11 Yellow HC, HC Yellow No. 12, HC Yellow No. 13, HC Yellow No. 14, HC Yellow No. 15, 2-amino-6-chloro 4-nitrophenol, picramic acid, 1,2-diamino-4-nitrobenzol, 1,4-diamino-2-nitrobenzol, 3-nitro-4-aminophenol, 1-hydroxy-2-amino-3-nitrobenzo 1 and 2 - hydroxyethylpicramic acid and mixtures thereof.

The dye composition may comprise a single direct dye or a combination of several direct dyes. The total amount of direct dye in the composition is preferably from 0.001 to 10% by weight relative to the total weight of the dye staining composition, preferably from 0.01 to 7.5%, more preferably from 0.05 to 5% by weight.

The composition may also comprise an oxidizing agent, particularly if lightening of the color is desired. If the dye composition is an oxidation dyeing composition, it preferably contains two components: a first component consisting of oxidation dye intermediates, in particular: at least one oxidation dye precursor, at least one coupler, and at least one alkalinization agent; a second component comprising at least one oxidizing agent, in particular hydrogen peroxide. Both components are usually packaged separately and mixed prior to application to the hair. The oxidation dyeing composition may optionally also include at least one direct dye.

Any intermediate product of oxidation dyes may be used. Examples of oxidation dye precursors are: para-phenylenediamine, toluene-2-5-diamine, 2-chloro-para-phenylenediamine, N-methoxyethyl-para-phenylenediamine, N, -N-bis (2-hydroxyethepara) phenylenediamine, 2- (2-hydroxyethyl) para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 4,4-diaminodiphenylamine, 1,3-bis (N- (2-hydroxyethyl) -N - (4-aminophenyl) amino) -2-propanol, PEG-3, 3,2'-para-phenylenediamine, para-aminophenol, para-methylaminophenol, 3-methyl-4-aminophenol, 2-aminomethyl 4-aminophenol, 2- (2-hydroxyethylaminomethyl) -4-amino-phenol, ortho-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol, 2- amino-5-acetamide, phenol, 4-diaminobenzoic acid, 5-aminosalicylic acid, 2,4,5,6-tetraaminopyrimidine, 2,5,6-triamino-4-hydroxypyrimidine, 4.5- diamino-1- (4-chlorobenzyl) pyrazole, 4,5-diamino-1-hydroxyethylpyrazole, and the salts thereof The concentration of dye precursor (s) is preferably between 0.001 and 10% by weight relative to the total weight of the dyeing composition, in particular between 0.01 and 7.5%, more preferably between 0.degree. , 1 and 5%. Examples of couplers are: meta-phenylenediamine, 2-diaminophenaxyethanol, 2-amino-4- (2-hydroxyethylamino) anisole, 2,4-diamino-5-methylphenetole, 2,5-diamino-5- ( 2-hydroxyethoxy) toluene, 2,4-dimethoxy-1,3-diamino benzene, 2,6-bis (2-hydroxyethylamino) toluene, 2,4-diamino-5-fluoro-toluene, 1, 3-bis- (2,4-diaminophenoxy), propane, meta-aminophenol, 2-methyl-5-amino phenol, 2-methyl-5- (2-hydroxyethylamino) phenol, 2,4-dichloro 3-aminophenol, 2-chloro-3-amino-6-methylphenol, 2-methyl-4-chloro-5-aminophenol, N-cyclopentylmetaaminophenol, 2-methyl-4-methoxy-5 (2-hydroxyethylamino) phenol, 2-methyl-4-fluoro-5-aminophenol, resorcinol, 2-methylresorcin, chlororesorcin, 1-naphthol, 1,5-dihydroxy naphthalene, , 7-dihydroxy naphthalene, 2,7-dihydroxynaphthalene, 2-isopropyl-5-methylphenol, 4-hydroxyindole, 5-hydroxyindole, 6-hydroxyindole, 7-hydrox indole, 6-hydroxybenzomorpholine, 3,4-methylenedioxyphenol, 2-bromo4,5-methylenedioxyphenol, 3,4-methylenedioxyaniline, 1- (2-hydroxyethyl) amino-3,4-methylenedioxybenzene, 6-Dihydroxy-3,4-dimethylpyridine, 2,6-dimethoxy-3,5-diaminopyridine, 2,3-diamino-6-methoxypyridine, 2-methylamino-3-amino-6- methoxy pyridine, 2-amino-3-hydroxypyridine, 2,6-diamino pyridine, and the salts of these substances and mixtures thereof. The concentration of coupler (s) is preferably between 0.001 and 10% by weight relative to the total weight of the dyeing composition, in particular between 0.01 and 7.5%, more preferably between 0.1 and 5%. Examples of basifying agents are: sodium hydroxide, ammonia or an ammonia salt, an alkanolamine such as monoethanolamine, isopropanolamine, propanol 2-amino-2-methyl, 2-aminobutanol or a salt thereof, alkanediamine such as 1,3-propanediamine or a salt thereof, a carbonate such as guanidine carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate and mixtures thereof . The concentration of basifying agent is preferably between 0.1 and 15% by weight relative to the total weight of the dye composition, in particular between 0.5 and 10%, more particularly between 1 and 7.5%.

In the oxidation dyeing composition, the component comprising the oxidizing agent is separately packaged and mixed with the dye component prior to application to the hair. Examples of oxidizing agents are: hydrogen peroxide, urea peroxide, melamine peroxide and sodium bromate.

The concentration of oxidizing agent (s), in particular hydrogen peroxide, is between 1 and 30% by weight, relative to the total weight of the dyeing composition, in particular between 1 and 15%, more preferably between 1 and 12. % and even more preferably 2 and 9%. The pH of the oxidizing agent is generally acidic, less than 6. After mixing the component consisting of oxidation dye intermediates with the component comprising the oxidizing agent, the pH of the dyeing composition must be basic, higher 7. After application of the dye composition, it should be left on the hair for at least 10 minutes, preferably between 10 and 60 minutes, even more preferably 30 minutes. According to a particularly suitable embodiment, the application of the dye composition is carried out on dry hair, preferably on dry and dirty hair.

Steps a) and b) are carried out successively, that is to say that the time interval between steps a) and b) is less than 3 hours, in particular less than 1 hour, preferably less than 30 minutes and very preferentially without delay. The hair should not be rinsed between steps a) and b).

Step b) involves applying to the hair a smoothing composition having an acidic pH of less than 6.9, and leaving the composition at least 10 minutes on the hair. Preferably, the smoothing composition has a pH of between 1 and 5. According to a particularly suitable and preferred embodiment, the smoothing composition comprises at least one carboxylic acid, especially at least one carboxylic acid of the formula: R-COOH in which R is chosen from a hydrogen atom, HCO, COOH, CN, optionally substituted with C 1 -C 10 alkyl optionally substituted, C 2 -C 10 alkenyl, optionally substituted with C 2 -C 15 alkynyl, optionally substituted with C 3 -C 15 Cycloalkyl, a C 6 -C 10 alkyl group, an aryl group or an optionally substituted 5- to 10-membered heteroaryl group, wherein the optional substituents of the alkyl group are selected from a halogen atom, a hydroxyl group, an amino group, and C 1 -C 4 alkoxy, and the optional substituents of the other groups are selected from halogen, hydroxyl, amino, C 1 -C 4 alkyl and C 1 -C 4 alkoxy.

It may be in particular glyoxylic acid, pyruvic acid and 2-ketobutyric acid. The concentration of the acid is preferably between 0.1 and 40% by weight, relative to the total weight of the smoothing composition, preferably between 0.5 and 30%, especially between 1 and 25% and even more preferentially. between 2.5 and 20%.

An example of a smoothing product is: - 10% to 30% glycoxylic acid - 10% to 20% carbocysteine - 1 to 5% amino acids. In step b), once applied, the smoothing composition is left on the hair for at least 10 minutes, preferably between 10 and 60 minutes, again. more preferably between 10 and 30 minutes. Step c) then involves heating the hair by drying it with a heat-generating hair dryer and / or passing a heat-releasing straightening iron. The temperature of the iron to be smoothed can be between 140 and 250 ° C. Preferentially step c) consists of drying the hair and passing a straightening iron. The method according to the invention may also comprise an additional step which consists in rinsing the hair between step b) and step c).

According to a variant, this additional step consists in rinsing the hair and in applying again the smoothing composition between step b) and step c) and leaving it on the hair between 5 and 60 min. This step allows to further perfect the smoothing. According to another aspect, the invention also relates to a hair coloring and smoothing kit for carrying out the method. This kit comprises at least: - a dyeing composition for the hair having an alkaline pH of at least 7.1, - a hair smoothing composition having an acid pH of less than 6.9, - a user manual repeating the steps of the method according to the invention. The coloring and smoothing compositions are as defined above for the description of the process.

The hair coloring and straightening kit according to the invention may also comprise other elements, in particular at least one shampoo and / or at least one hair mask and / or a serum for perfecting the appearance of the hair. The invention is now illustrated by non-limiting examples of methods and kits and by test results. For this first example, use is made of a kit comprising in% by weight: 1 / a dyeing composition consisting of: - 0.25 amonium chloride, - 8.00 amoniaque 25% - 0.30 fragrance / fragrance - 0, P-toluene diamine - 0.28 resorcinol - 0.01 m -phenylenediamine 3024646 11 - pH 9.5 - Water qs 100% This dye composition is mixed with a 6% solution of H 2 O 2 with a weight ratio of 1 : 1 before application on the hair. 2 / a smoothing composition consisting of: - 10.00 glyoxylic acid - 1.5 amodimethicone - 0.30 fragrance / fragrance - Sodium hydroxide qsp pH 1.5 - Water qs 100% The process consists of the implementation following steps: - apply on dry and dirty hair, the dye composition, and leave the composition for 30 minutes on the hair, - apply on the hair the smoothing composition and leave the composition 15 minutes on the hair, 5 - rinse, and - dry the hair and pass a straightener. The duration of implementation of this method does not exceed 45 minutes. EXAMPLE 2 For this second example, a kit comprising in% by weight is used: 1 / a dyeing composition consisting of: - 0.25 amonium chloride, - 0.80 monoethanolamine - 0.30 fragrance / perfume - 0.55 p-toluene diamine - 0.28 resorcinol - 0.01 m -resorcinol phenylened - pH 9.5 - Water qs 100% This dye composition is mixed with a 6% H 2 O 2 solution with a weight ratio of 1: 1 before application on the hair. 2 / a smoothing composition consisting of: - 10.00 glyoxylic acid - 1.5 amodimethicone - 0.30 fragrance / perfume - Water qs 100% The process consists in the implementation of the following steps: dry hair and dirty, the dye composition, and leave the composition 15 minutes on the hair, - apply on the hair the smoothing composition and let the composition 15 minutes on the hair, 5 - rinse, and - dry the hair and pass a hair straightener. The duration of implementation of this method does not exceed 30 minutes. Example 3 For this third example, a kit comprising in% by weight is used: 1 / a dye composition consisting of: - 0.30 amonium chloride, - 1.00 monoethanolamine - 0.50 fragrance / perfume - 0.55 p-toluene diamine - 0.28 resorcinol - 0.28 m -resorcinol phenylened - pH of 10.00 - Water qs 100% This dye composition is mixed with a 6% solution of H 2 O 2 with a weight ratio of 1: 1 before application on the hair. 2 / a smoothing composition consisting of: - 10.00 glyoxylic acid - 1.5 amodimethicone 3024646 13 - 0.30 fragrance / fragrance - Sodium hydroxide qsp pH 1.5 - Water qs 100% The process consists of the setting the following steps are carried out: - applying the dyeing composition to dry and dirty hair, and leaving the composition for 30 minutes on the hair, - applying the smoothing composition to the hair and leaving the composition for 10 minutes on the hair, 5 - rinse, - reapply the smoothing composition, - rinse, - dry the hair and pass a hair straightener. The duration of implementation of this process does not exceed 55 minutes. Trials demonstrating the effectiveness of the process Four strands of white hair were subjected to a staining treatment.

A composition for hair dyeing by oxidation comprising the following ingredients was used (the percentages being given by weight relative to the total weight of the composition): 0.5333% of toluene-2,5-diamine sulphate 0, 2667% Resorcinol 15 5.00% isopropyl alcohol 0.50% sodium sulphite 0.20% by weight% ascorbic acid 8.00 weight% ammonia 25% water qs 100% The composition was mixed with a 6% aqueous solution of hydrogen peroxide in a ratio of 1: 1 to prepare the oxidation dye composition. The composition thus obtained was applied to the locks of dry hair in a ratio of 1: 3, and distributed evenly by combing. An exposure time of 20 minutes has been respected.

Two of the four locks served as reference samples and were not subjected to smoothing. They were rinsed and dried with a hair dryer. The other two locks were treated with a 20% by weight smoothing composition of glyoxylic acid having a pH of 1.8 in a 1: 1.5 ratio of smoothing solution to dry hair. The smoothing composition was evenly distributed with a comb on the locks that contained the rinsed stain solution. There is an increase in temperature due to the acidic base exothermic reaction. The smoothing preparation is applied for a period of 15 minutes at room temperature. Then, the locks are dried with a hair dryer and smoothed with a hair straightener at a temperature of 170 ° C.

After rinsing the locks with water (for 30 sec.), The locks were spontaneously dried at room temperature and the colors were observed. Next, each treated and untreated lock was immersed in 100 ml of a solution. to 5% sodium lauryl sulphate in a bath with stirring for 30 minutes at 40 ° C. The sodium lauryl sulphate solution was clear. Visual inspection also showed that the locks treated according to the present invention had a darker color. This shows that the method of the present invention not only allows the achievement of coloring and smoothing in the same session, but improves the wash resistance and durability of the color. The dyed and smoothed hair obtained with the process according to the invention are silky and smooth. The process according to the invention thus makes it possible to obtain a radiant color which is resistant to several washes in a more durable manner than when a process is carried out without exothermic reaction, by rinsing the hair between the coloring and the smoothing. In addition, the smooth effect withstands several washes.

Claims (18)

REVENDICATIONS1. An exothermic hair dyeing and smoothing process comprising at least the following steps in the order of: a) applying to hair a hair dye composition having an alkaline pH of at least 7.1, and leaving the composition at least 10 minutes on the hair b) apply on the hair a smoothing composition for the hair having an acid pH lower than 6.9, and leave the composition at least 10 minutes on the hair - c) dry the hair and / or pass a straightener, steps a) and b) being performed successively without rinsing. 2. A method of dyeing and straightening hair according to the claim characterized in that the dye composition has a pH of between 7.1 and 11. 3. Hair dyeing and smoothing process according to one of the preceding claims, characterized in that the dye composition has a pH of between 8 and 11. 4. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the dye composition comprises - at least one direct dye - and / or at least one oxidation dye precursor and at least one coupler , And optionally at least one alkalizing agent and / or at least one oxidizing agent for the hair. 5. A method of dyeing and straightening hair according to one of the preceding claims, characterized in that the dye composition comprises hydrogen peroxide. 6. A method of dyeing and straightening hair according to one of the preceding claims, characterized in that the smoothing composition has a pH of between 1 and 6.9. 3024646 16 7. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the smoothing composition has a pH of between 1 and 5. 8. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the smoothing composition comprises at least one carboxylic acid. 9. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the smoothing composition comprises at least one carboxylic acid of the formula: R-COOH wherein R is selected from hydrogen atom, HCO , COOH, CN. 10. A method of dyeing and straightening hair according to one of the preceding claims, characterized in that the method comprises an additional step of rinsing the hair between step b) and step c). 15 11. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the method comprises a further step of rinsing the hair and reapplying the smoothing composition between step b) and step c) and leave on the hair between 5 and 60 min. 12. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the dye composition is left on the hair in step a) for 10 to 60 minutes. 13. A method of dyeing and straightening hair according to one of the preceding claims, characterized in that step a) is performed on dry hair and possibly dirty. 14. Hair dyeing and straightening method according to one of the preceding claims, characterized in that the smoothing composition is left on the hair in step b) for 10 to 60 minutes. 15. A method of dyeing and straightening hair according to one of the preceding claims, characterized in that the temperature of the iron to be smoothed in step c) is between 140 and 250 ° C. 16. Coloring and hair straightening kit for carrying out a process according to one of the preceding claims, characterized in that it comprises: a dyeing composition for the hair having an alkaline pH of at least 7.1, - a hair smoothing composition having an acidic pH of less than 6.9, - a user's guide repeating the steps of the method according to one of the preceding claims. 5 17. Hair coloring and straightening kit according to claim 16, characterized in that it also comprises at least one shampoo and / or at least one hair mask. 18. Staining and hair straightening kit according to claim. 16 or 17, characterized in that the dye composition is a composition as defined in claims 2 to 5 and the smoothing composition is a composition as defined in claims 6 to 9.