Process For Straightening Human Hair

Abstract

Human hair is straightened by a two-stage process wherein the hair is first submitted to the action of a keratin softener and after removal of at least part of the softener from the hair is then treated with a swelling or penetration-promoting agent, while being straightened mechanically. The hair is finally subjected to the action of a fixation or neutralizing agent. The treatment reduces damage to the hair due to chemical or mechanical action.

Description

BACKGROUND OF THE INVENTION

To straighten curly human hair, compositions are usually employed which contain keratin softening agents such as alkali hydroxides, sulfites or bisulfites, or salts of mercapto carboxylic acids. These compositions are usually in the form of pastes or creams and are applied to the individual strands of the dry hair or to hair which is still wet from a pre-washing with a shampoo. The cream in this case must be distributed on the hair as uniformly as possible by application by hand or with a comb. The cream is permitted to act on the hair for a time between 10 and 60 minutes. During this time, the hair must be smoothed out from time to time with the fingers of the operator or with a comb until the desired straightening is accomplished. Subsequently, the hair is thoroughly rinsed with water in order to remove the straightening agents from the hair. The final step is a neutralization stage wherein, if the straightening agent contained alkali hydroxide, the hair is treated with acid, while in the case of reducing sulfites or bisulfites or mercapto carboxylic acid salts the aftertreatment is effected with an oxidizing agent, such as hydrogen peroxide, a perborate or a bromate.

The straightening effect that can be obtained in this process depends largely on the treatment time for the straightening agent, the concentration of the keratin softening agent, and the pH of the composition. In order to obtain an adequate and long-acting straightening of the hair, it is necessary that the agent has a sufficiently high effective concentration and a suitable pH value and is permitted to act long enough upon the hair. The hair keratin is softened to an increasing degree during the treatment time and thus steadily loses strength so that it can be mechanically smoothed out from time to time by hand or with a comb.

With this type of chemical and mechanical treatment applied to the hair, damage to the hair is frequently unavoidable and appears as breaking of the hair and loss of hair. Additionally, the hands of the operator, as well as the scalp of the customer, are frequently affected.

Attempts have been made to improve the action of the described hair-straightening operation by adding to the straightening agent hair-swelling compounds such as urea, formamide, acetamide, urethane and similar materials. While this permitted to shorten the treatment time and to lower the concentration of effective agent and the pH, no substantial improvement could be obtained in so far as the injury to the hair and skin was concerned because in this case the keratin softening and swelling compounds were permitted to act upon the hair simultaneously, resulting in an increased stress for the hair. This applies also to the process described in German published application 1,467,912 where the hair-softening agent and the swelling agent are kept separate but are combined shortly before the straightening treatment is initiated.

It is therefore an object of the present invention to provide for a hair-straightening operation which avoids the aforementioned hair and skin damage, or reduces them substantially.

SUMMARY OF THE INVENTION

This is accomplished by a two-stage process wherein, in the first stage, the hair is subjected to the action of a keratin softener which is then removed at least partly whereupon, in a second stage, the hair is treated with a swelling or penetration-promoting agent while being straightened out mechanically. At the end of the process, the hair may be subjected to a fixation or neutralizing treatment in conventional manner.

DETAILED DESCRIPTION OF THE INVENTION AND OF PREFERRED EMBODIMENTS

The straightening agents used in the first stage of the process may be alkali hydroxides such as sodium hydroxide or potassium hydroxide. If sulfites or bisulfites are used, they may be used in the form of the alkali or ammonium salts. If a mercapto carboxylic acid is used, the preferred compounds would be thioglycolic acid and thiolactic acid which can be used in the form of their water-soluble salts, for instance as ammonium-, alkali- or monoethanolamine salts.

The time of treatment with the keratin-softening agent is preferably between 5 and 8 minutes. During this time a mechanical action affecting the hair or skin is preferably avoided. This is possible because the customary repeated smoothing of the hair with a comb or by hand is not necessary in case of the present invention during this stage of the treatment. Only at the end of the treatment the major part of the straightening agent may be removed by combing the hair.

In the second stage the swelling or penetration-promoting agents are applied to the hair which, however, are physiologically harmless both for the hair and the skin. Preferably, this stage is carried out by treatment for about 3 to 10 minutes, during which time the hair is repeatedly thoroughly combed. This will hardly affect the hair.

The process according to the present invention permits to apply the keratin-softening agent in the first stage at a substantially lower concentration of effective agent, at a lower pH value, and for a shorter time of treatment. Thus, the hair and skin are chemically substantially less affected, and the agent in this treatment is therefore physiologically more compatible with the body. However, with these comparatively low values of concentration, pH and treatment time a suffient straightening could not be obtained by conventional straightening processes.

Surprisingly, it was found out, however, that if following this first stage the straightening agent is largely removed from the hair and the hair subsequently treated with a composition containing hair-swelling agents or penetration-promoting agents, a sufficient straightening effect can be obtained. This is all the more surprising since the agents employed in the second stage by themselves have no straightening effect.

The swelling or penetration-promoting agents may be in particular lower monohydric aliphatic alcohols of two to four carbon atoms, aromatic alcohols such as particularly benzyl alcohols, aliphatic diols or ether alcohols of five to six carbon atoms, water-soluble sulfoxides and sulfones, water-soluble rhodanides, thiourea, as well as urea and water-soluble derivatives of thiourea and urea.

The important point for the selection of the listed compounds is that they are adapted to increase the hair-straightening effect of the keratin-softening agents because of their swelling or penetration-promoting properties. These compounds can either be used in the compositions of the second state singly or in mixture. The total concentration preferably is between 5 and 30 percent by weight.

The concentration of the keratin softener preferably is 1 to 13 percent, the pH 5 to 13.5.

There are variations possible in the described process, depending on the different structure and type of the naturally curly hair. Ordinarily, the process is carried out at room temperature. However, sometimes the application of heat may be advantageous.

It will be understood that the agents used in the two stages of the process according to the present invention may be applied in the conventional form as used in the cosmetics industry, for instance as solutions, emulsions, creams or gels. It is preferred, however, to employ the hair-straightening agent in the first stage in a form where it has a thickened consistency, for instance as a cream. In the second stage, the compositions can be used both as liquid preparations and as preparations of a higher consistency.

In both stages of the process, the usual additives as employed in the cosmetics industry may be added, such as solution promoters, perfume oils, thickeners, hair conditioners such as lanolin and lecithin, as well as wetting agents and other customary materials. It is also possible, by addition of oxidative or direct dyes, to obtain simultaneously a dyeing of the hair.

The invention will be further illustrated by the following examples:

EXAMPLE 1

A cream was formed of the following composition:

8.0 g thioglycolic acid 5.4 g cetyl alcohol 1.8 g paraffin oil 3.9 g oleyl alcohol, with 20 mole ethylene oxide oxyethylated 1.5 g colloidal silicic acid 12.3 g ammonia (25%) 67.1 g water Total: 100.0 g

The cream contained 9.3 percent ammonium thioglycolate, 1.6 percent free ammonia and had a pH value of 9.6

The cream was applied to the individual strands of the hair, which had previously been washed with a shampoo. It was easily distributed in this manner onto the hair. After a treatment time of 5 minutes, the major part of the composition was removed by combing.

In the second stage of the process a composition of the following composition was applied to the hair: ##SPC1##

After a treatment time of 5-7 minutes, during which time the hair was repeatedly thoroughly combed, the hair was then thoroughly rinsed with water, whereupon a fixation agent was applied in the form of 100 ml of a 2 percent hydrogen peroxide solution.

The hair was in this manner thoroughly and lastingly straightened without damage.

The same results were also obtained by using in the first stage a similar composition of a lower pH value and permitting it to act upon the hair somewhat longer, that is, for 8 minutes.

This composition was likewise in the form of a cream and was as follows:

8.0 g thioglycolic acid 5.4 g cetyl alcohol 1.8 g paraffin oil 3.9 g oleyl alcohol, with, mole 20 ethylene oxide oxyethylated 1.5 g colloidal silicic acid 5.9 g ammonia (25%) 5.5 g ammonium bicarbonate 68.0 g water Total: 100.0 g

The cream contained 9.3 percent ammonium thioglycolate and had a pH of 8.2. The further treatment was exactly as in Example 1.

EXAMPLE 2

A hair-straightening composition of the consistency of a gel was applied which was composed as follows:

5.0 g sodium hydroxide 5.0 g tragacanth 90.0 g water Total: 100.0 g

The pH of this composition was 13.2. The composition was applied to the curly hair and was uniformly spread on the hair. It was permitted to act for 5 minutes, whereupon the major part of it was removed by combing. Thereafter, a gel-type composition was applied as follows:

1.5 g "Carbopol 960" of the Goodrich Company (ammonium salt of a carboxyvinylpolymerizate) 69.5 g water 3.5 g urea 10.5 g 2,2-dimethyl-1,3-propane diol 15.0 g isopropyl alcohol Total: 100.0 g

The composition was permitted to remain on the hair for 4 minutes while the hair was several times subjected to combing. Subsequently, the hair was thoroughly rinsed with water. The hair thus was straightened perfectly and with lasting effect without any damage.

The same results were obtained by employing, again, in the first stage, a corresponding composition having a lower alkali contents but applying it for a slightly longer period of time, that is for 7 minutes. This composition consisted of the following:

2.0 g sodium hydroxide 5.0 g tragacanth 93.0 g water Total: 100.0 g

The pH of this composition was 12.8.

The further treatment was the same as in Example 2. The hair was finally subjected to a neutralizing treatment with citric acid of a 3 percent concentration.

EXAMPLE 3

A gel-type straightening agent was used of the following composition:

36.5 g 35% concentration aqueous ammonium sulfite solution (density 1.18 with 22.7 g S0.sub.2 per 100 ml) 3.5 g "Carbopol 960" (ammonium salt of a carboxyvinyl polymerizate) 60.0 g water Total: 100.0 g

The composition was applied to the curly hair which had previously been shampooed and was spread easily. After a treatment time of 15 minutes, the gel was for the most part removed by combing.

Subsequently, a cream was applied to the hair which cream had the following composition:

20.5 g cetylstearyl alcohol 2.5 g sodium lauryl sulfate 4.0 g "Texapon N 25" of the Dehydag Company (an aqueous sodium laurylether sulfate solution containing 28% of this compound) 53.0 g water 6.0 g benzyl alcohol 14.0 g ammonium rhodanide Total: 100.0 g

The composition was permitted to act upon the hair for 10 minutes, during which time the hair was repeatedly combed. The composition was then rinsed out thoroughly with water.

A fixation rinse of conventional form was then applied in form of a solution of 8.4 g of perborax containing 17.3 percent oxygen [Na.sub.2 B.sub.4 O.sub.7 .sup.. (H.sub.2 O.sub.2 ).sub.3.sub.-4 ] dissolved in 500 ml. water.

There was thus produced an adequate and lasting straightening of the hair without damage.

The following examples, Examples 4-9, describe alternative compositions which may be used in the second stage of the process of the invention. In the first stage any of the keratin-softening agents disclosed in Examples 1-3 may be employed.

EXAMPLE 4

A solid mixture of 25 g urea and 5 g potassium rhodanide which is dissolved prior to use in 70 ml water.

EXAMPLE 5

A powder formed of 12 g of dimethylsulfone which is dissolved prior to use in 88 ml water.

EXAMPLE 6

A solution of 5 g methyl urea, 6 g hexanediol--1,6 and 8 g n-propylalcohol dissolved in 81 ml water.

EXAMPLE 7

A solution of 2 g of lauryl pyridinium chloride and 18 g 3-methoxybutanol-1 in 80 ml water.

EXAMPLE 8

In this case a composition was applied in the second stage of the process according to the present invention which included a dye for the hair. The composition was composed as follows:

9.0 g cetylstearyl alcohol 0.5 g lanolin 1.0 g sodium lauryl sulfate 8.0 g pinacol 8.0 g ethyl alcohol 12.0 g urea 0.5 g perfume oil 0.05 g"Acilanbraun R," extra high concentration (Bayer Company, Color Index No. 14,805 ) 61.0 g water

Application of this composition resulted in a red-brown color for the hair.

EXAMPLE 9

A composition was applied in this example which likewise dyed the hair. It was as follows:

12.0 g urea 10.0 g dimethylsulfoxide 0.015 g "Acilan black 10 B" of the Bayer Company (Color Index No. 20,470) 0.03 g "Acilan brown R," extra high concentration (Bayer Co., Color Index No. 14,805) 75.0 g water

This composition resulted in a brown-to-black color for the hair.

EXAMPLE 10

This example likewise involved a composition by which the hair was simultaneously dyed. It was as follows: ##SPC2##

Fixation was then effected with a solution as disclosed in Example 1. The hair thus was given a brown color.

All percentages in the above examples are by weight.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the stadpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

Claims

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims is:

1. A process for straightening human hair, comprising subjecting the hair first to the action of a keratin softener, then removing the major part of the softener from the hair, thereafter treating the hair with a swelling or penetration-promoting agent while straightening it mechanically.

2. The process of claim 1, wherein the mechanical straightening is effected by repeatedly combing the hair.

3. The process of claim 1, wherein the hair after treating it with the swelling or penetration-promoting agent is subjected to the action of a fixation or neutralizing agent.

4. The process of claim 1, wherein the keratin softener is selected from the group consisting of alkali hydroxides, alkali sulfites, ammonium sulfites, alkali bisulfites, ammonium bisulfites, and water-soluble salts of mercapto carboxylic acids.

5. The process of claim 4, wherein the keratin softener includes thioglycolic acid, sodium hydroxide or an aqueous ammonium sulfite solution as part of the active ingredient.

6. The process of claim 1, wherein the swelling or penetration-promoting agent is selected from the group consisting of monobasic aliphatic alcohols of two to four carbon atoms, aromatic alcohols, aliphatic diols, aliphatic diols of five to six carbon atoms, ether alcohols of five to six carbon atoms, water-soluble sulfoxides, water-soluble sulfones, water-soluble rhodanides, thiourea, urea, water-soluble derivatives of thiourea, water-soluble derivatives of urea and mixtures of the compounds.

7. The process of claim 6, wherein the swelling and penetration-promoting agent includes at least one of the following: urea, methylurea, thiourea, potassium rhodanide, sulfone or dimethylsulfoxide as part of the active ingredients.

8. The process of claim 1, wherein the keratin softener is permitted to act upon the hair for a period of 5-8 minutes during which period the hair is not subjected to combing or other mechanical action.

9. The process of claim 1, wherein the swelling or penetration-promoting agent is permitted to act upon the hair for a period of 3-10 minutes during which time the hair is repeatedly combed.

10. The process of claim 1, wherein the total swelling or penetration-promoting agent is applied in a concentration between 5 and 30 percent by weight.

11. The process of claim 1, wherein the keratin softener is applied in the form of a paste or cream.

12. The process of claim 1, wherein the keratin softener is applied in a composition of a pH range between about 5 and 13.5.