GB2038385A - A permanent waving composition - Google Patents

Abstract

An improved permanent waving composition is provided, which comprises an aqueous solution of cysteine and N-carbamoylcysteine having a pH adjusted to the range of from 8 to 10, wherein the combined concentration of cysteine and N- carbamoylcysteine is within the range of from 3 to 20% by weight and the molar ratio of cysteine to N- carbamoylcysteine ranges from 90:10 to 20:80.

Description

SPECIFICATION A permanent waving composition The present invention relates to a permanent waving composition comprising cysteine and Ncarbamoylcysteine.

According to the present invention, there is provided a permanent waving composition comprising an aqueous solution containing cysteine and N-carbamoylcysteine having a pH adjusted to the range of from 8 to 10, wherein the combined concentration of cysteine and N-carbamoylcysteine is within the range of from 3 to 20% by weight and the molar ratio of cysteine to N-carbamoylcysteine ranges from 90:10 to 20:80.

In one aspect, the present invention provides a permanent waving composition which acts mildiy on the human hair and skin, has not any offensive odour, and shows outstanding stability during storage as well as during application. The permanent waving composition may not only be suitable for waving the hair, but also usable for straightening naturally or artificially curled hair.

A conventional process now in use for the permanent waving of hair comprises a first step wherein the hair is treated with an aqueous solution containing one or more sulfhydryl compounds in order to reduce the disulfide linkages of keratin. The permanent waving composition which has been most commonly employed contains thioglycolic acids as sulfhydryl compounds (hereinafter referred to as main ingredients) to achieve the foregoing purpose. Thioglycolic acids, however, have a peculiar foul odour and act violently on the hair, and thus tend to cause break or loss of hair, and decreased luster of hair. Still worse, thioglycolic acids occasionally lead to a rash on the scalp or damage to the skin and hair roots.

In recent years, permanent waving compositions containing cysteine which has a mild action on the hair and skin without emitting an unpleasant odour has been in wide use, in the place of thioglycolic acids possessing inherent drawbacks as aforesaid. Notwithstanding, permanent waving compositions, comprising cysteine alone as the main ingredient, are liable to degrade during storage due to cysteine being oxidized to produce cystine which is hardly soluble in water and separates out as crystals, thereby resulting in a considerable decrease in the commercial value of the compositions. Moreover, during the course of permanent waving, cystine sometimes separates out in the form of crystals and adheres to the hair or scalp of the customer or to the hands of the hairdresser, and in some instances causing discomfort.Since crystals of cystine are not removable even when washed with water, the adhesion of cystine not only reduces the work efficiency, but also, on occasion, leaves white powder on the hair to impart and unattractive appearance of the finished hair. Furthermore, cystine, when adhering to the hands of the hairdresser, especially to crotches of fingers, becomes firmly bonded to the skin, and is her'ce not easily removable. At the present time, the adhesion of cystine is an occupational problem of the hairdresser.

The present invention is for a permanent waving composition which possesses a mild action on the hair or skin such as a cysteine-type permanent waving composition, has no offensive odour, and is also superior in stability during storage and application, which is a notorious drawback associated with a permanent waving composition mainly containing cysteine; this can be accomplished by a permanent waving composition comprising N-carbamoylcysteine as a main ingredient. This invention is already disclosed in the Japanese Patent Publication No. 56327/1978.

That is, the present invention is to provide a permanent waving composition which is characterized in that the composition comprises an aqueous solution containing cysteine and Ncarbamoylcysteine, whose pH is adjusted to the range of from 8 to 1 0, in which the combined concentration of cysteine and N-.carbamoylcysteine is within 3 to 20% by weight and the molar ratio of cysteine to N-carbamoylcysteine ranges from 90:10 to 20:80. In cases where cysteine is contained in a greater proportion than the cysteine to N-carbamoylcysteine molar ratio of 90:10, the stability during storage and application deteriorates, and accordingly, the compositions have to contain Ncarbamoylcysteine, at least, in a greater proportion than the cysteine to N-carbamoylcysteine molar ratio of 90:10.When the stability is strongly required in particular, the compositions should preferably contain N-carbamoylcysteine in a proportion greater than the cysteine to N-carbamoylcysteine molar ratio of 70:30. With an increase in a proportion of N-carbamoylcysteine, the stability of the permanent waving compositions increases, and further the wave retaining capability is also improved.

Nevertheless, even when N-carbamoylcysteine is used in a greater proportion than the cysteine to Ncarbamoylcysteine of 20:80, the wave retaining capability is no longer improved. Moreover, the increased amount of N-carbamoylcysteine in the compositions is likely to reduce, more or less, the waving effect of imparting waves to the hair. Furthermore, with a larger amount of N-carbamoylcysteine employed, the hair after treatment gives a somewhat rigid feeling and appears a little coarse to the touch.

As a matter of fact, when the permanent waving compositions are really in a wide and commercial use, it is a serious and important problem whether they are more costly than conventional permanent waving compositions, in addition to such functional qualities as stated earlier. Insofar as Ncarbamoylcysteine is produced from cysteine, it is obvious that N-carbamoylcysteine is more expensive than cysteine. Hence, the smaller amount of N-carbamoylcysteine capable of affording functional properties to satisfaction is desirable. Further since N-carbamoylcysteine has about 1.35 times the molecular weight of cysteine, the combined amount of cysteine and N-carbamoylcysteine contained in the compositions increases with the increase in the proportion of N-carbamoylcysteine, to produce equal reducing force originated in sulfhydryl groups.Thus, use in a larger proportion of Ncarbamoylcysteine is not desired, either, from a viewpoint of economy.

As is apparent from the foregoing explanation, when the stability of the permanent waving compositions, waving effects, wave retaining capability, touch and feel of the hair after permanent waving, economy and the like are totally taken into consideration, the permanent waving compositions with the cysteine to N-carbamoylcysteine molar ratio ranging from 90:10 to 20:80 meet such requirements'most and are much superior in practical usefulness. The permanent waving compositions having said molar ratio between 70:30 and 50:50 are more preferable.

The permanent waving compositions of the present invention contain cysteine and Ncarbamoylcysteine normally in the combined concentration of 3 to 20% by weight. In the case of cold waving performed at room temperature, the concentration of 5 to 10% by weight is preferred. For use in permanent waving at elevated temperatures, lower concentrations may be used.

The permanent waving compositions of the present invention are in the form of an aqueous solution and the pH valuers are adjusted to the range of 8 to 10, more preferably 8.7 to 9.5. The pH is adjusted with a variety of inorganic bases or organic bases. Inorganic bases include ammonia, and potassium hydroxide. Organic bases include monoethanolamine, triethanolamine and other amines.

Among these bases, monoethanolamine is preferable.

In addition to the foregoing main ingredients of cysteine and N-carbamoylcysteine and pH adjusting agents, penetrating agents, metal chelating agents and other additives are normally contained in the permanent waving compositions of the present invention to enhance the waving effect. The penetrating agent allows the main ingredients to penetrate into the hair more effectively to provide a stabilized permanent waving effect. The penetrating agents include polyoxyethylene, higher alcohol ethers or higher fatty acid esters thereof, and the like. Other surface active agents are also usable. These penetrating agents are employed normally in a concentration of about 0.1 to 1% by weight. The metal chelating agent is effective in enhancing the stability of the main ingredients and also in giving an attractive finish to the hair.The chelating agents include ethylenediaminetetraacetic acid (EDTA) or water-soluble salts thereof. The chelating agent is employed in a concentration of 0.01 to 0.1% by weight. Other additives, if necessary, such as antiseptics, wetting agents, thickeners, perfumes, colouring agents and the like may be further contained in the present permanent waving compositions.

The permanent waving compositions of the present invention are applied to the hair by the cold waving process, elevated temperature waving process, or ironing process used for the male hair. These processes are well known in detail to those skilled in the art. In waving the hair by the cold waving process, the hair is held in the desired form, to which the present cold waving composition is sufficiently applied to plasticize the hair, then subjected to an oxidizing condition to fix the form. Fixation is carried out in any known manner, for example, by being exposed to air for a long period of time or by being brought into contact with an aqueous solution containing an inorganic oxidizing agent for a short period of time. The inorganic oxidizing agents include alkali metal salts of bromic acid, hydrogen peroxide and the like.

The permanent waving compositions of the present invention are not only applicable to waving the hair, but also to uncuriing naturally or artificially curled hair. In the latter case, the hair is wetted with the permanent waving composition, thereafter straightened, and then fixed in the straight form.

Cysteine which is at present produced on an industrial scale is of L-form, and in the present invention L-form cysteine is normally employed. DL-form or D-form may, of course, be employed. Ncarbamoyl-cysteine, whether of L-form, D-form or DL-form, makes no difference in chemical properties of optical isomers, and thus each of L-form, D-form or DL-form may be effectively employed. As was already shown in the Japanese Patent Publication No. 56327/1978, substantial differences in the effects as the main ingredient could not be observed between N-carbamoyl-L-cysteine and Ncarbamoyl-DL-cysteine.L-cysteine is produced by hydrolysis of the human hair and N-carbamoyl-Lcysteine can be prepared easily by reacting L-cysteine with potassium cyanate. Since N-carbamoyl-DLcysteine is obtained by hydrolyzing with alkali 2-aminothiazoline-4-carboxylic acid which is synthesized from an inexpensive industrial material, it may be prepared probably more economically than Ncarbamoyl-L-cysteine, if only the sufficient demand is present. N-carbamoyl-L-cysteine and Ncarbamoyl-DL-cysteine are both extremely low in toxicity. The LD50 values of these compounds as measured on mice by oral administration are 13.5 g/kg for N-carbamoyl-L-cysteine and 13.1 g/kg for N carbamoyl-DL-cysteine.

The permanent waving compositions of the present invention act moderately on the human hair or skin, possess no foul odour, and produce much superior effects in the stability during storage and application and the wave retaining capability, as compared with the compositions containing cysteine as the single main ingredient. Particularly, the compositions containing N-carbamoylcysteine in a greater proportion than the cysteine to N-carbamoylcysteine molar ratio of 70:30 precipitate no white powder, even when stored in the air for a long period of time, consequently, never fail to bring about such a phenomenon that the white powder adheres to the hands of the hairdresser during permanent waving.Even where the molar ratio is within the range of from 90:10 to 70:30, the compositions provide a satisfactory practicality if stored or applied with care, in fact, are by far superior as compared with the permanent waving compositions comprising cysteine alone as the main ingredient.

Following is a description by way of example only of methods of carrying the invention into effect.

EXAMPLE 1 The eight kinds of permanent waving solutions were prepared as given in Table 1, varying ratios of cysteine to N-carbamoyl-L-cysteine, then tested for storage stability. These solutions comprise such basic composition as shown below: Combined amount of L-cysteine and N-carbamoyl-L-cysteine 0.05 mole Monoethanolamine 3.8 to 4.1 ml Tetrasodiu m ethylenedia minetetraacetate 0.05g Total volume of solution 100 ml pH (260C) 9.1 The amounts of L-cysteine, N-carbamoyl-L-cysteine and monoethanolamine in the test solutions are provided in Table 1.Each of the solutions was prepared by adding monoethanolamine (about 3 ml), L-cysteine, N-carbamoyl-L-cysteine, and tetrasodium ethylenediaminetetraacetate to about 80 ml of purified water in that order described with stirring, then the total volume of each solution was adjusted to 100 ml while adjusting pH to 9.1 with monoethanolamine. The total amount of monoethanolamine used for each solution is given in Table 1. The test solutions containing L-cysteine alone, N carbamoylcysteine alone, or cysteine and N-carbamoylcysteine at the molar ratio of 10:90 are not Examples, but Reference Examples.

TABLE t

N-carbamoyl L-cysteine L-cysteine Mono- Days elapsed (A) (B) (A) /(B) ethanol- before pre molar amine cipitation Test solutions (9) (mole) (9) (mole) ratio (ml) (days) Ref. Example 1 6.1 0.050 0 0 100:0 3.4 9 Examples A 5.5 0.045 0.82 0.005 90: 10 3.5 15 0.040 e 4.8 0.040 1.6 0.010 80:20 3.6 32 C 4.2 0.035 2.5 0.015 70:30 3.6 Over 60 D 3.6 0.030 3.3 0.020 60:40 3.7 E 3.0 0.025 4.1 0.025 50:50 3.8 F F 2.4 0.020 4.9 0.030 40:60 3.9 G 1.8 0.015 5.8 0.035 30::70 40 H 1.2 0.010 6.6 0.040 20:80 4.0 Ref. Example 2 0.6 0.005 7.4 0.045 10:90 4.1 Ref. Example 3 ~1 0 0 8.2 0.050 0:100 4.2 The test solution prepared on the same day were charged into 200 mi wide-mouthed reagent bottles respectively, and allowed to stand at room temperature (20 to 260C) for 60 days with the mouths open.From Reference Example 1 Solution containing L-cysteine alone, white powder of cystine separated out on the 9th day, while Test Solutions A and B containing L-cysteine and Ncarbamoylcysteine precipitated white powder on the 15th day and 32nd day, respectively. No white powder was observed in Test Solutions C, D, E, F, G, H and Reference Example 2 and 3 Solutions, even after the lapse of 60 days. As is self-explanatory from the foregoing results, the compositions of the present invention are all exceedingly superior in the storage stability.

EXAMPLE 2 Cold waving solutions A, B, C, D, E, F, G, H and Reference Examples 1,2 and 3 were prepared which correspond to Test Solutions A, B, C, D, E, F, G, H and Reference Examples 1,2 and 3, as shown in Table 1. These cold waving solutions had the similar compositions to those of the test solutions, with the exception that 0.5 g of polyoxyethylene(n=20) oleyl ether was added to 100 ml of each solution.

That is, these cold waving solutions comprise the following ingredients and concentrations: Combined amount of L-cysteine and N-carbamoyl-L-cysteine 0.05 mole/100 ml Polyoxyethylene (n=20) oleyl ether 0.5 g/1 00 ml Tetrasodium ethylenediaminetetraacetate 0.05 g/100 ml Monoethanolamine Amount used for the adjustment of pH pH (260C) 9.1 These cold waving solutions were tested for the waving effect.

At first, about 400 filaments of untreated human hair were bundled and fastened together with a thread at one end, then shampooed and dried to prepare a hair specimen having a uniform filament length of 25 cm. The specimen wetted with each of the above cold waving solutions was wound on a curler with 1 cm diameter, then allowed to stand at room temperature for 20 minutes. The specimen was then rinsed with water to remove the waving solution, thereafter wetted with a 5% potassium bromate solution and allowed to stand for 1 5 minutes. The specimen was rinsed with water, then lightly dewatered and removed from the curler.

Immediately after the above treatment, the specimen was held in suspension, and the length of the specimen (linear distance between opposite ends) was measured in a wet state. The specimen in this state was allowed to stand indoors for 2 days, and the length of the spontaneously dried specimen was measured in a similar manner.

In this way, eight kinds of the cold waving solutions of the present invention containing L-cysteine and N-carbamoyl-L-cysteine were tested, concurrently with the cold waving Reference Solutions containing L-cysteine alone, N-carbamoyl-L-cysteine alone, or L-cysteine and N-carbamoyl-L-cysteine at the molar ratio of 10:90, and the waving effects were compared. The waving effect was calculated according to the following equation.

L0-L Waving effect (%) = x 100 L0 wherein L0 is the initial length of the hair (25 cm), and L is the length of the treated hair.

Waving effect (average value of n=2) of each solution and the appearance of the treated hair are tabulated in Table 2.

TABLE 2

Waving effect ( /ç) Molar ratio of L-cysteine Immediately Appearance Touch and Feel Cold waving to N-carbamoyl- after 2 days of treated of solutions L-cysteine treatment later hair treated hair Ref. Example 1 100:0 22.3 11.4 Slight deposition Rigid, and coarse of white powder in sutface Examples PI 90:10 21.3 11.5 Reduced luster Soft, and smooth B 80:20 20.5 12.0 Good luster C 70:30 20.0 12.2 ,, Soft, and very smooth D 60:40 19A 12.7 E 50:50 18.7 13.0 F 40:60 18.4 13.0 ,, Soft, and smooth G 30:70 17.9 14.5 H 20:80 17.7 15.2 Ref. Example 2 10 :-90 17.5 15.0 ,, Somewhat rigid Ref. Example 3 0:100 17.3 15.2 ,, Reference Example 1 Solution containing L-cysteine alone exhibited the best waving effect immediately after treatment but the poorest waving effect when measured two day later. That is, Reference Example 1 Solution was inferior in wave retaining capability.Adversely, the cold permanent waving solutions of the present invention, i.e., Example Solutions A, B, C, D, E, F, G and H produced lower waving effect than Reference Example 1 Solution and decreased with an increase in the proportion of N-carbamoyl-L-cysteine immediately after treatment, while the waving effect achieved two days later had, inversely, a tendency to increase, which showed superior wave retaining capability over the solution containing only L-cysteine.

Moreover, the hair treated with Reference Example 1 Solution appeared somewhat whitish and ugly because of deposition of cystine. In contrast, with the cold permanent waving solutions of the present invention, Solutions B to H exhibited no such phenomenon and were superior in luster, with the exception that Solution A resulted in the slight decrease in luster of the hair.

As regards touch and feel of the treated hair, the hair treated with Reference Example 1 Solution was felt coarse in surface due to deposition of cystine and was rigid to the touch. Each hair treated with each of Solutions A to H was felt soft and smooth, especially superior touch and feel was obtained with Solutions C to E. The hairs treated with Reference Example 3 Solution containing N-carbamoyl-Lcysteine alone, Reference Example 2 Solution containing N-carbamoyl-L-cysteine in an exceeding proportion over the L-cysteine to N-carbamoyl-L-cysteine molar ratio of 20:80 were felt somewhat rigid to the touch and feel.

Claims (3)

1. A permanent waving composition comprising an aqueous solution containing cysteine and Ncarbamoylcysteine having a pH adjusted to the range of from 8 to 10, wherein the combined concentration of cysteine and N-carbamoylcysteine is within the range of from 3 to 20% by weight and the molar ratio of cysteine to N-carbamoylcysteine ranges from 90:10 to 20:80.

2. A permanent waving composition of Claim 1, wherein the molar ratio of cysteine to Ncarbamoylcysteine ranges from 70:30 to 50:50.

3. A composition as claimed in Claim 1 and substantially as described in any one of the specific examples hereinbefore set forth.