US 2719814 A
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ing reaction between a United St HAIR WAVING LorroN John W. Haefele, Mount Healthy, Ohio, assignor to The Procter & Gamble Company, lvorydale, Cincinnati, Ohio, a corporation of Ohio No Drawing. Application September 10, 1953, Serial No. 379,462
11 Claims. (Cl. 167-87.!)
The present invention relates to reducing agents for keratin, and more particularly to reducing agents possessing effective reducing power in prolonged periods of contact with keratin-containing substances without imparting undesirable damage thereto, a characteristic of particular advantage in the treatment of human'hair.
Mercaptans are now widely recognized as one of the most useful chemical reagents for softening hair and other keratin-containing substances, certain mercaptans (notably thioglycolic acid) having achieved wide commercial success in cold hair Waving procedures. However, these same mercaptans are also used as depilatories and it is ordinarily necessary, therefore, in order to soften a keratin-containing material without irreparably damaging same, to control carefully the period of contact between the mercaptan and the keratinous material being treated.
Thus, in the waving of human hair by means of mercaptan lotions the exercise of precaution in time of contact is particularly important, because, if this time of contact exceeds that necessary to accomplish the desired reduction of the hair, the hair can be rendered harsh and lowered in tensile strength. Since the speed of the reducmercaptan and the keratin of the hair is dependent on so many diverse factors, such as shaft diameter, porosity, chemical composition, and condition of the hair at the time of treatment, i. e. oiliness, etc., it is impossible to generalize as to the correct duration of contact. A given contact time that may be optimum for the hair of one individual may prove detrimental or otherwise unsatisfactory for the hair of another individual due to the tremendous and frequently unaccountable variation in susceptibility .to the reducing action of mercaptans which occurs from one person to another.
It is an object of this invention to provide mercaptan compositions which are safer to use in reducing keratinous substances than ordinary mercaptan solutions. Another object is to provide reducing compositions which will react with keratin at a satisfactory rate to produce a desired reduced keratin but which will react further to effect damage only at a greatly retarded rate. A further object is to render mercaptans less harsh and damaging to keratin-containing substances Without destroying their ability to reduce the keratin sufiiciently to modify the physical form and shape of the substance containing the said keratin. A still further object is to provide improved mercaptan reducing lotions for use in hair waving operations. Another object is to provide a mercaptan reducing agent which may be employed in the treatment of keratin with high degree of safety against damage thus permitting an increase in the period during which the mercaptan reagent may be safely left in contact with desirably reduced keratin and thus minimizing the importance of the variations in the character and reducibility of the hair from one individual to another.
The present invention is based on the discovery that the addition to the mercaptan solutions of the corresponding disulfides in certain proportions has the characteristic of retarding the usual undesirable excessive reaction of the mercaptan which causes hair damage, without at the same time affecting unfavorably the desirable reducing reaction of the mercaptan with the keratin. The compositions of my invention in aqueous, solution under the usual conditions of alkalinity known in the art may thus be effectively employed to reduce keratin with markedly greater safety against damage than has normally been possible heretofore. Mercaptans which react in this characteristic manner to the addition of organic disulfide and which come within the scope of my invention are the water-soluble, non-tertiary mercapto-carboxylic, or mercapto-sulfonic, acids of the general formula,
HSG-Z Where Z represents a radical selected from the group consisting of carboxyl (--CO2H) and sulfonic (SOzH), and G represents an alkylene radical containing at least 2 carbon atoms and composed exclusively of carbon and hydrogen atoms except for the presence of from 0 to 2 functional groups each of which is chosen from the class consisting of mercapto (SH), carboxyl (COzH) and sulfonic (SO3H) acid groups. By non-tertiary mercaptocompounds I mean, of course, mercaptans in which each mercapto- (SH) group. is attached to a primary or secondary carbon atom instead of to a tertiary carbon atom. Included in this collection of mercaptans are the following:
Thiohydracrylic acid and its position isomer tat-mercapto ethyl sulfonate Dithioglyceric acid SH I H HOOCCSH Dithiotartaric acid fi-Mercapto butyric acid H1 H0 GCHzC-CHs and its position isomers, ecand 'y-mercapto butyric acid and ocand fi-mercapto isobutyric acid;
,S-Mercapto, 'y-sulfobutyric acid and its position isomers;
1-mercapto 2-sulfo B-mercapto propane SH and its position isomers;
l-mercapto 2-4 disulfobutane and its position isomers;
the same non-tertiary mercaptans and conform to the general formula where Z and Z", like Z above, each represents a radical selected from the group consisting of carboxyl (CO2H) and sulfonic (SO3H), and G and G", like G above, each represents an alkylene radical containing at least 2 carbon atoms and composed exclusively of carbon and hydrogen atoms except for the presence of from to 2 functional groups each of which is chosen from the class consisting of mercapto (SH), carboxyl (--COzH) and sulfonic (SO3H) acid groups. It is preferable that all functional groups, i. e. the carboxyl (-CO2H) and sulfonic (--SO3H) as well the mercapto- (SH) and disulfide (-S-S) groups, be attached to non-tertiary carbon atoms in the compounds of this invention.
Those compositions are particularly preferred in which the alkylene radicals in both the mercaptan and the organic disulfide are all unsubstituted, i. e., in the general formulae given above, each of the radicals G, G and G" is composed exclusively of carbon and hydrogen atoms, the number of functional groups present in each being 0. Particularly important within this preferred class of compounds are those in which each of the alkylene radicals G, G, and G" contains from 2 to 3 carbon atoms, because the presence of unsubstituted alkylene radicals containing more than 3 carbon atoms tends to detract from the water-solubility of the compound. However, there does not appear to be any critical upper limit on the chain length of the alkylene radicals G, G and G" so long as the resultant compound is water-soluble.
The following example indicates the effect of the added disulfide in reducing damage caused by the mercaptan lotion.
Example I.A strand of 12 individual human hairs was wound on a mandrel having a diameter of 6.5 mm. and then immersed in a solution ammoniacal to a pH of about 9.0 and containing 5.4% thiohydracrylic acid (0.51 molal) but a negligible amount of organic disulfide. After 12 minutes in this solution at a temperature of 100 F., the strand was rinsed in water, treated with an oxidant fixative solution, and then rinsed in water again. The Wave strand was then unwound, the dimensions of the curl measured and an indication of the strength of the wet hair determined on the Scott 1P2 Serigraph machine which is described below. Measurements made with this machine on the hair before and after treatment were used to determine the 20% index,
a factor indicating the extent of damage, the lower the 20% index figure the greater the indicated damage.
In the above test the resultant curl had a diameter of 7.1 mm. and showed a 20% index of 0.62. In a comparative test on a curl formed under similar conditions except with the addition of about 2.1% dithio-dihydracrylic acid to the mercaptan solution, a curl diameter of 8.3 mm. was produced but the 20% index increased to 0.74. In this solution the molar ratio of dithio-dihydracrylic acid to thiohydracrylic acid was about O.2:1.0, giving a numerical ratio of disulfide groups to rnercaptan groups of 0.2:l.0. An increase in the dithio-dihydracrylic acid content to about 4.4% (numerical disulfide to mercaptan group ratio of about 0411.0) resulted in a further reduction in damage, the 20% index being about 0.82, and the curl diameter being about 8.2 mm.
The same pattern of an increasing degree of protection as the molar ratio of the disulfide to the rnercaptan, i. e. the amount of disulfide added to a given mercaptan solution, is increased has been consistently noted throughout my work. This work has included solutions containing from about 1 to 15% by weight of the rnercaptan at pHs from about 7.0 to about 10. It should be noted that, as is the custom with mercaptan solutions, the higher pHs within the above range are generally used in solutions with the lower concentrations of rnercaptan and conversely the lower pHs are employed when the concentration of mercaptans tends to lie in the upper part of the above range. This protective action of the added disulfide can be observed at numerical ratios of disulfide to mercaptan groups from about 0.l:l.0 to about 1.5 11.0 provided the time of immersion of the hair in the various solutions is sufficient to produce an effective wave i. e. generally at least 5 minutes. It should be pointed out that, due to the large difference in the relative quantities of waving solution in contact with the hair when a test curl is immersed in a test tube of solution. and when the solution is simply applied to the hair during one-the-head waving, a time of 5 minutes immersion of the test curl in a test tube is equivalent to an exposure time of about 45 minutes or more in actual application waving on the head.
On October 28, 1952, a patent, U. S. 2,615,828, was granted to me on compositions containing mercaptans in admixture with organic thiosulfides. As is pointed out in that patent, the mercaptans and organic thiosulfate interact to form disulfide and inorganic sulfite. The instant invention, however, contemplates the addition of only the disulfide to the mercaptan solution and these two substances interact only by interchange of organic groups to form another disulfide and another rnercaptan, mole for mole. The present compositions are thus differentiated from those of U. S. 2,615,828 by their substantial freedom from inorganic sulfite and organic thio sulfate.
In accordance with my observations, the addition of the organic disulfide does tend to reduce somewhat the speed with which the mercapto-carboxylic, or rnercapto-sulfonic, acids react with the keratin and thereby extends somewhat the contact time necessary for desirable reduction. However, the protective action oflered by the disulfide against damage heretofore experienced in prolonged exposure, especially in the novel proportions hereinafter stated, more than compensates for the lowering of the reactivity of the rnercapto-carboxylic, or mercaptosulfonic, acid with unreduced keratin. In other words, with increase in disulfide content of the solution the safety factor increases more rapidly than does the contact time required for adequate reduction. Thus the compositions of my invention can be used in hair waving and other keratin treating operations with much greater safety than is normally possible due to the protective action imparted to the compositions by the presence of limited amounts of the organic disulfide modifying agent. A distinct advantage is that with marked reduced danger due to over-exposure, directions for use are more easily standardized, thereby enabling non-professional users, who for some reason cannot select a time of exposure without some danger of unsatisfactory result, to employ the reducing composition with safety and obtain an acceptable wave with minimum damage; The compositions of my inventions, particularly those mixtures in which the numerical ratio of disulfide groups to mercaptan groups is above 0.4:1.0, are especially adapted for use in the simplified technique of permanent waving commonly known as the no neutrali'zer method, in which the Wave is allowed to become fixed merely by exposure to the air without the application of any special oxidizing solution.
The efficacy of compositions of my invention, especially as regards hair waving, cannot be evaluated accurately by damage considerations alone and overall performance is therefore determined by a series of tests involving evaluation of a number of measured characteristics of the treated hair, including curl diameter and curl length, as Well as damage.
In the case of curl diameter a strand of 12 human hairs 4.25 inches in length and cemented at each end is wetwound on a mandrel 6.5 mm. in diameter, then saturated for a given time at 100 F. with the keratin reducing solution. After the wound strand of hair has been exposed to the solution for the given contact time, the solution is rinsed from the strand which is then treated with a solution of inorganic oxidizing agents for 3 minutes to set or fix the curl. Following application of the fixing agent the hair is again rinsed, removed from the mandrel and, while Wet and without assistance from external force, is allowed to assume a circular curl which is measured for average diameter. From the information available, deficiency in tightness or D. I. T. of the curl is determined as follows:
D. I. T.=
With all variables except reducing solution held constant, D. I. T. is of course indicative of waving efficiency of the solution. The lower the D. I.T. value, the higher the effectiveness.
Curl length is an indication of both waving efficiency of the reducing solution and damage suffered by the hair during contact with the solution. When freshly formed curls are suspended by the end and shaken up and down, the elasticity or spring of the formed coil may be observed. The degree of laxity of the spiral coil is indicative of waving efiiciency of the solution and the degree of damage effected thereby. Numerical indication of this characteristic is obtained by measuring the curl length. The longer the curl, the greater the damage, assuming of course adequate potential efiiciency in the reducing solution.
Damage caused by excessive contact of the hair with the solution is also indicated by a factor termed 20% index. In thedetermination of this factor, an apparatus known as the Scott 1P2 Serigraph is used. This instrument is designed to record the stretch of keratin-containing fibers by the application of a uniformly increasing load. The ratio of the load required after treatment of the fibers to the load required before treatment to stretch a wet strand of 12 fibers 20% of the original length is referred to as the 20% index, the higher the index, the lower the reduction in fiber strength and hence the lower the damage. The instrument is equipped with two clamps between which the strand of 12 fibers of keratin-containing substance is mounted. The strand is surrounded by a watersaturated wicking arrangement which keeps the hair Wet during stretching. One of the clamps is fixed to a bar which inclines at a uniform rate when the machine is in operation, and the other clamp is attached to a weighted and away from the inclined. As the the stretch load applied by carriage adapted to travel along the bar first mentioned clamp when the bar is inclination of the bar increases,
r, rive at a single quantity that permits the carriage increases at a uniform rate and the strand of fibers is elongated. The relation between load and elongation is continuously recorded on a chart by a pen fixed to the moving carriage. When the elongation of the strand reaches 20% of the original length between the clamps, the machine is reversed and the bar slowly and uniformly returns to horizontal position. With decrease in load the strand contracts, usually at a rate less than the rate of elongation, thereby forming a hysteresis loop on the chart. The load required to effect 20% stretch can be read from the chart.
The difiiculty in making direct comparisons of curls produced under difierent exposure times is readily evident because in addition to the fixed variables there are a number of measured variables. For example, assume that a given reducing solution produces the following result:
Exposure Time (min) Length D. I. T. 20% Index From the above table it will be observed that the 6 minute curl has the best length but that the 8 minute curl is tighter and that damage increases steadily with exposure time. It has heretofore been difiicult to choose from such results an optimum time for a given reducing solution.
In order that a fair evaluation of the overall eificiency of the reducing solution may be determined, a method of weighting the different measurements in order to ardirect comparison of results of different experiments, and especially of different series of experiments, has been established. Toward this end, the extreme values which are normally encountered in permanent Waving studies have been set for the important variables as follows:
Minimum Maximum Curl Length (mm) 100 D. I. T 0 100 Damage (as 20% Index) 1.0 0
Curl Partial Curl Value Length D. I. I. 20% Index 1 D. I. T. values over are, of course, possible and in special cases it is useful to assign them, but, normally, curls having D. I. T. values over 100 are of no interest.
The Curl value is defined as the sum of the partial curl values for length (L), deficiency in tightness (D. I. T.), and damage (D), so that the curl value is equal to the sum of the partial curl values for L, D. I. T., and D. Obviously the best possible curl will have a curl value of 3, and the poorer the curl, the higher the curl value.
When a series of experiments is conducted with a given reducing solution at varying times of contact, it
is found that the curl value gradually decreases to a minimum and then increases. The minimum point is usually clear-cut, although a good solution may stay at its minimum curl value over an extended period of time. A curl value of 8 has been arbitrarily chosen on the basis of past experience as the maximum value indicating an acceptable curl achieved by well known and acceptable commercial reducing solutions.
The minimum curl value attainable is, of course, a measure of the quality of the solution, that is, it measures the optimum that can be achieved with that solution.
The time to reach minimum curl value is a measure of the speed of the reducing action of the solution weighted with respect to both damage and waving.
The duration of a given curl value, such as 8 or below, for example, over increasing times of contact is indicative of the effective safety period of the solution. In other words, the effective safety period is a measure of the length of time during which an acceptable curl may be obtained without danger of objectionable damage.
In the example cited above showing actual determinations for-curl length, D. I. T. and 20% index, the following partial curl values are noted.
It will be observed that a minimum curl value of 8 was obtained after an exposure time of 7 minutes.
With the above explanations the results obtained with reducing solutions of my invention as set forth in the following examples will be readily understood. It is to be borne in mind, however, that the specific conditions given in the examples, wherein all parts shown are by weight, are merely illustrative of the broader aspects of the invention more fully covered in the appended claims.
Example Il.-5.4 parts (0.051 mol) of thiohydracrylic acid and 2.9 parts (0.014 mol) of dithiodihydracrylic acid were mixed with water and concentrated ammonium hydroxide (28% NI-Is) to bring the total to 100 parts and the pH to 9.0. In this solution the numerical ratio of disulfide groups to mercaptan groups was about 0.2:1.0. Portions of this solution were used to produce a number of test curls of hair by exposure of individual curls from the same head of hair for variable times. Partial curl values for length, deficiency in tightness, and damage were determined in accordance with the methods described above. The curl value of the solution of this example reached a minimum of after exposure of the test curl to the solution for minutes and the duration of time during which a curl value of 8 or less was obtained was about 480 minutes.
In comparison with this performance, a corresponding solution at pH about 9.0 and containing about 0.051 mol thiohydracrylic acid per 100 parts of solution but containing no dithiodihydracrylic acid when used to curl switches of the same hair produced a minimum curl value of 7 after 7 minutes exposure. Moreover, the duration of time of exposure during which curl values of 8 or less were obtained was only 7 minutes.
Example I1l.--An aqueous solution similar to that of Example II but containing a greater proportion of dithiodihydracrylic acid was prepared from 5.4 parts (0.051 mol) thiohydracrylic acid, 4.4. parts (0.021 mol) dithiodihydracrylic acid and suificient water and ammonium hydroxide to bring the total to 100 parts and the pH to 9.0. The numerical ratio of disulfide groups to mercaptan groups in this solution was about 04:10 This solution was tested over a range of exposure times as above described and it was found that a minimum curl value of 5 was achieved after 20 minutes exposure and the duration of time during which a curl value of 8 or less was obtained was about 580 minutes.
Example IV.-An aqueous solution similar to that of Examples II and III but containing a greater proportion of disulfide was prepared from 5.4 parts (0.051 mol) thiohydracrylic acid, 9.5 parts (0.045 mol) dithiodihydracrylic acid and sufficient water and ammonium hydroxide to bring the total to 100 parts and the pH to 9.0. The numerical ratio of disulfide groups to mercaptan groups in this solution was about 09:10. A minimum curl value of 5 was obtained after minutes exposure to this solution. The duration of exposure during which a curl value of 8 or less was obtained was about 180 minutes.
Even higher numerical ratios of disulfide groups (as dithiodihydracrylic acid) to mercaptan groups (as thiohydracrylic acid) than those covered by the above examples were examined for their effect upon waving performance. For example, the effective safety period for a numerical ratio of about 1.6:1.0 was only about 62 minutes. In this manner it Was determined that the effective safety period passed through a maximum value of about 900 minutes at a numerical ratio of disulfide to mercaptan groups of about 0.6: 1.0; and it was found that compositions containing disulfide in amounts greater than 1.5 disulfide groups per mercaptan group failed to produce high quality curls over any practical range of exposure times.
Other mercaptan-disulfide systems containing compounds within the abovedefined class of carboxylic and sulfonic acid mercaptans and disulfides were also investigated including among others thiolactic acid and its disulfide and mercapto-butyric acid and its disulfide. In general, useful and worthwhile improvement in protective action and safety were obtained at all numerical ratios of disulfide to mercaptan groups from about 0.10110 to about 15:10, the disulfide addition producing the safe waving action of the highest quality at numerical ratios of 0.25: 1.0 to 0.75 1.0. Specific examples of the improved performance of additional systems are detailed below.
Example V.The 20% index on a 12 strand switch of hair immersed for 60 minutes in a solution ammoniacal to pH 9.3 and containing 6.8% by weight of B-mercapto butyric acid but substantially free of disulfide was only 0.18. However, treatment of a switch of the same hair for 60 minutes in a solution of the same character except with a 5.4% content of the disulfide of fl-mercapto butyric acid (numerical ratio of disulfide group to mercaptan group of about 0.4:1.0) produced a curl with a 20% index of 0.42, the higher value being indicative of the much less severe damage caused by the latter solution.
Example Vl.5.7 parts (0.054 mol) of thiolactic acid and 7.1 parts (0.034 mol) of dithiodilactic acid were mixed with water and concentrated ammonium hydroxide (28% NHa) to bring the total to .100 parts and the pH to 9.3. In this solution the numerical ratio of disulfide groups (as dithiodilactic acid) to mercaptan groups (as thiolactic acid) was about 06:10. Portions of this solution were used to produce a number of test curls of hair by exposure of standard twelve-hair strands for variable times. The curl values of the resulting curls were determined and found to reach a minimum of 6 after exposure to the test solution for 9 minutes and the duration of time during which a curl value of 8 or less was obtained was about 27 minutes. I In comparison a corresponding aqueous solution at pH 9.3 and containing 0.055 mol of thiolactic acid but only about 0.001 mol of dithiodilactic acid per parts of solution, produced curls with a minimum curl value of 8 after 5 minutes exposure and an effective safety period (time during which a curl value of 8 or less was obtained) of only 1 minute.
Example VII.-A solution ammoniacal to a pH of 9.3 and containing 0.05 mols of B-mercapto-'y-sulfo-butyric acid and 0.02 mols of its own disulfide per 100 grams showed good curling with increased hair protection over that obtained with a similar solution without any added disulfide.
Example VIII.The 20% index on a sample of hair immersed for 24 hours in a solution ammoniacal to pH of 9.3 and containing 0.05 moles of thiomalic acid per 100 grams of solution but substantially free of disulfide was only 0.22. However, treatment of a sample of the same hair for 24 hours in a solution of the same character except with the addition of 0.02 moles of dithio-dirnalic acid per 100 grams of solution produced a curl with 20% index of 0.66, the higher value being indicative of the much greater protective action of the latter solution on long time exposure.
Example IX.The 20% index on a test curl formed by treating a standard hair strand for 15 minutes in a solution containing 0.055 mole of s-rnercapto-butyl sulfonic acid per 100 grams of solution and adjusted to a pH of 9.3 by the addition of sodium hydroxide was 0.51. A strand of the same hair after 15 minutes solution in a similar solution containing the same amount of fi-mercapto butyl sulfonic acid and, in addition, 0.011 mole of its disulfide per 100 grams (numerical ratio of disulfide to mercaptan groups of about 0.2:1.0) showed a 20% index of 0.75.
Example X .The 20% index on a strand of hair after treatment for 60 minutes in a solution containing 0.055 moles of B-mercapto-ethyl sulfonic acid per 100 grams of solutions and adjusted to a pH of 9.3 by the addition of ammonium hydroxide was only 0.31. Similar treatment of a strand of the same hair for 60 minutes in a solution ammoniacal to the same pH and containing the same concentration of B-mercaptoethyl-sulfonic acid but containing also 0.011 mole of its disulfide per 100 grams of solution produced a curl with a 20% index value of 0.65, the higher value being indicative of the much less severe damage caused by the latter solution.
The compositions of this invention may be prepared either by dissolving the organic disulfide in the mercaptan solution directly or by oxidizing a portion of the mercaptan already in solution to form the disulfide in situ. In either case, the concentration of the mercapto-carboxylic, or mercapto-sulfonic acid in the active mercaptan form in the finished solution should be at least 1% by weight and for cold hair waving preferably in the range of 4 to 9% by weight, although as much as 15% by weight may be useful with certain species, especially those of higher molecular weight.
Example XI.0.05 mols of dithioglyceric acid is dissolved in about 60 cc. of water, the pH is adjusted to about 8 by the addition of concentrated ammonium hydroxide (28% NI-Ia), and 6.8 grams of hydrogen peroxide solution (10% strength) is added, su'liicient to oxidize two fifths of the total mercaptan groups present to disulfide groups. The resulting solution, which contains disulfide groups and mercaptan groups in a numerical ratio of 1 to 3 or 0.33 1.0, after being adjusted to 100 parts total and a pH of 9.3 by the addition of water and ammonia, shows good quality waving performance with increased protec tion over a similar solution containing per 100 grams 0.03 mol of dithioglyceric acid and no disulfide.
In the art of waving hair wherein compositions of the present invention are particularly useful, it is preferable that the alkalinity be maintained at a pH value between 8.5 and 9.5, but in the treatment of other keratin-containing substances such as Wool for the purpose of effecting reduction of keratin, pH values from about 7 to about 10 can be employed, and the protective action of the disulfide as exemplified above is clearly evident throughout this entire pH range.
In the preparation of compositions for use in waving hair, the preferred alkalizing medium is ammonia, it being well known that solutions of mercaptans which have been so alkalized are superior for this use to comparable solutions which have been rendered alkaline by the addition of other alkalizing materials such as potassium carbonates and hydroxides. Part of the reason for the superiority of ammonia as an alkalizer resides in the lower destructive action which ammoniacal solutions generally show toward the keratin-containing substance. Therefore, in the practice of the present invention, the protective action of the disulfide demonstrated above is sometimes of slightly greater advantage in the case of solutions rendered alkaline by the addition of alkali metal hydroxides, such as sodium hydroxide as in Example IX, or carbonates, or mixtures thereof with ammonia. Other alkalizing agents including water-soluble amines such as ethyl amine, monoethanolamine and morpholine, and also water-soluble quaternary ammonium bases such as tetraethyl ammonium hydroxide can also be used. All of these alkaline agents, and mixtures thereof, may be substituted for the ammonium hydroxide employed in the foregoing examples, in appropriate quantities, with generally comparable results.
While the essential ingredients of the compositions of my invention include one or more of each of the previously defined classes of compounds, namely mercaptans and disulfides, it is to be understood that other ingredients such as perfume, opacifying agents, buffers and other additives designed to impart especially desired qualities to the reducing solution may be incorporated without departing from the spirit of the invention.
The term consisting essentially of is used herein in the definition of the ingredients whose presence in the claimed composition is' essential, and as used it is intended to exclude the presence of other materials in such amounts as to interfere substantially with the properties and characteristics possessed by the composition set forth but to permit the presence of other materials in such amounts as not substantially to affect said properties and characteristics adversely.
Having thus described my invention, what I claim and desire to secure by Letters Patent is:
1. A hair waving lotion for effectively waving hair without imparting undesirable damage thereto even in prolonged periods of contact, consisting essentially of a mixture in aqueous solution of water-soluble non-tertiary mercaptan of the general formula,
and water-soluble, non-tertiary, organic disulfide of the general formula,
Where Z, Z and Z" each represents a radical selected from the group consisting of carboxyl (-CO2H) and sulfonic (fiSOsH), and G, G and G" each represents an alkylene radical containing at least 2 carbon atoms and composed exclusively of carbon and hydrogen atoms except for the presence of from 0 to 2 functional groups each of which is chosen from the class consisting of mercapto (AH), carboxyl (-CO2H) and sulfonic (-SO3H) acid groups, the amount of said mercaptan being from about 1 to about 15% by weight of the solution, the numerical ratio of organic disulfide, groups to mercapto groups in solution being from about 010110 to about 1.5: 1.0, the pH of the solution being from about 8.5 to about 9.5, and the solution being substantially free from both sulfite and organic thiosulfate.
2. A hair waving lotion as in claim 1 in which each of the radicals G, G and G" is composed exclusively of carbon and hydrogen atoms.
3. A composition as in claim 2 in which each of the radicals G, G and G" contains from 2 to 3 carbon atoms.
4. A hair waving lotion as in claim 1 in which the lotion is ammoniacal to a pH from about 8.5 to about 9.5.
5. A hair waving lotion as in claim 4 in which the amount of mercaptan is from about 1 to about 9% by Weight and the numerical ratio of organic disulfide groups 11 to mercaptan groups is between about 0.25: 1.0 and about 0.75:1.0.
6. A hair waving lotion for effectively waving hair without imparting undesirable damage thereto even in prolonged periods of contact, consisting essentially of a mixture in aqueous solution of water-soluble non-tertiary mercapto-carboxylie acid of the general formula,
and water-soluble, non-tertiary organic disulfide of the general formula,
Where G, G and G each represents an alkylene radical containing at least 2 carbon atoms and composed exclusively of carbon and hydrogen atoms except for the presence of from to 2 functional groups each of which is chosen from the class consisting of mercapto (-SH), carboxyl (CO2H) and sulfonic (-SO3H) acid groups, the amount of said mercapto-carboxylic acid being from about 1 to about by weight of the solution, the numerical ratio of organic disulfide groups to mercapto groups in solution being from about 0.10:1.0 to about 1.5 :1.0, the pH of the solution being from about 8.5 to about 9.5, and the solution being substantially free from both sulfite and organic thiosulfate.
7. The hair waving lotion of claim 6 in which the mercapto-carboxylic acid is thiohydracrylic acid and the organic disulfide is dithiodihydracrylic acid.
8. The hair waving lotion of claim 6 in which the mercaptocarboxylic acid is thiolactic acid and the organic disulfide is dithiodilactic acid.
9. A hair waving lotion for effectively waving hair without imparting undesirable damage thereto even in prolonged periods of contact, consisting essentially of a mixture in aqueous solution of water-soluble non-tertiary mercapto-sulfonic acid of the general formula,
and water-soluble, nontertiary, organic disulfide of the general formula,
where G, G and G each represents an alkylcne radical containing at least 2 carbon atoms and composed exclusively of carbon and hydrogen atoms except for the presence of from 0 to 2 functional groups each of which is chosen from the class consisting of mercapto (SH), carboxyl (-CO2H) and sulfonic (SO3H) acid groups, the amount of said mercapto-sulfonic acid being from about 1 to about 15% by weight of the solution, the numerical ratio of organic disulfide groups to mercapto groups in solution being from about 0.10:1.0 to about 15:10, the pH of the solution being from about 8.5 to about 9.5, and the solution being substantially free from both sulfite and organic thiosulfate.
10. A hair waving lotion as in claim 9 in which the amount of mcrcapto-sulfonic acid is from about 4% to about 9% by weight and the numerical ratio of organic disulfide groups to mercaptan groups is between about 0.25:1.0 and about 0.75:1.0.
11. The hair waving lotion of claim 9 in which the mercapto-sulfonic acid is B-mercapto ethyl sulfonic acid and the organic disulfide is the disulfide of B-mercapto ethyl sulfonic acid.
Dahle et al., Methods Analyzing Cold Wave Solutions, Am. Perfumer, Feb. 1945, pp. 3548.