Abstract:
A liquid composition for increasing hair body by permanently swelling hair shafts with reduced loss of tensile strength comprises an aqueous solution of a hair cleansing synthetic detergent containing a bisulfite salt and dimethyl urea. The composition also preferably contains a cationic hair conditioner and hydroxyalkyl solvent. An amphoteric detergent base is preferred. The composition may be applied and rinsed out with water after a few minutes to increase hair body, and the applications may be repeated to further swell the hair without undue damage to the hair.

Description:
BACKGROUND AND PRIOR ART 
     Women with fine, hard-to-manage hair experience a need to build more body and thickness into their hair. Hair waving lotions can be used for this purpose, such as those containing a salt of thioglycolic acid. The hair is treated with the waving lotion and set on large rollers. After several minutes of reaction, it is rinsed with water and treated with a solution of hydrogen peroxide. This treatment swells the hair shafts, thereby increasing the body of the hair and giving the appearance of a fuller head of hair. A disadvantage of this procedure is that the hair shafts are damaged, tensile break strength being appreciably reduced, especially if the treatment is repeated. Since it may be desirable to treat fine hair to increase its body at frequent intervals, such as every one to two weeks, the use of waving lotions for this purpose can result in serious damage to the hair. 
     Hair waving lotions containing bisulfite salts, such as sodium bisulfite, are known, although they have not been widely used on a commercial basis. See, for example, U.S. Pat. Nos. 2,836,185, 2,836,543, 2,817,342, and 3,583,408. These patents also propose the use of nitrogen compounds, such as amines and amides, in combination with the bisulfite salt to promote swelling of the hair. Under certain conditions of use it is disclosed that a sulfite-amide composition can result in reduced hair damage (U.S. Pat. Nos. 2,836,185 and 2,836,543), but U.S. Pat. No. 3,583,408 proposes the use of a polymerizable vinylic monomer as an auxiliary treating agent to compensate for the loss of strength of the hair due to treatments with reagents such as bisulfite and urea. U.S. Pat. No. 2,836,543 proposes the use of auxiliary swelling agents such as pyrocatechol or gentisic acid. 
     SUMMARY OF INVENTION 
     In accordance with the present invention, the liquid base of the composition for increasing hair body comprises an aqueous solution of a hair cleansing synthetic detergent in an effective hair washing concentration for undiluted application. There is incorporated in this base solution an effective concentration of a bisulfite salt to reduce the cystine (--S--S--) linkages of the hair, thereby permitting swelling of the hair shafts to occur. The composition also contains a limited concentration of a specific swelling agent (N.N&#39;-dimethyl urea), such as preferably 3 to 8% by weight. The pH is preferably controlled to minimize bleaching of the hair and to substantially prevent alkaline hydrolysis. In preferred embodiments, the composition also contains a small amount of cationic hair conditioner, which can be incorporated without difficulty where the synthetic detergent is an amphoteric detergent fully compatible with cationic nitrogen compounds. Also, an auxiliary swelling agent may be included, such as a minor proportion of a water-miscible hydroxyalkyl solvent. 
     Compositions of the kind described can be used for increasing hair body by permanently swelling hair shafts with reduced loss of tensile strength. By having the bodying agents in the detergent solution, the treatment of the hair can be carefully controlled. The composition is applied full strength, lathered as a shampoo, and left on the hair with the reducing and swelling agents acting in the presence of the detergent. To terminate the treatment all that is required is to quickly rinse the hair in water, the presence of the detergent assuring that the reducing and swelling agents will be immediately and thoroughly removed. The cationic conditioning agents, being substantive to the hair, will remain thereon, and it is believed that their action will help to offset any damage to the hair. It is believed that the thoroughness of removal of the reducing and swelling agents because of the presence of the detergent encourages the immediate re-forming of at least a portion of the cystine cross-links that were broken by the reducing action. Also, after the hair is dry, air oxidation will promote further re-forming of the cystine bonds. 
     DETAILED DESCRIPTION 
     In practicing the present invention, it is important to employ as the base of the liquid composition an aqueous solution of a hair cleansing synthetic detergent in an effective hair washing concentration for undiluted application. For example, the concentration on the basis of the total liquid composition can range from 5 to 20% by weight, such as a concentration of about 10%. Any synthetic hair cleansing detergent can be used which is compatible with the other ingredients, including non-ionic, cationic and anionic synthetic detergents. However, it is preferred to employ an amphoteric detergent, such as cocoamidopropyl betaine or cocobetaine. Such amphoteric detergents are available commercially. (Richardson Company, Lemont, Ill.) Imidazoline detergents can also be used, such as Miranol C2M (Miranol Chemical Co., Irvington, N.J.) 
     The bisulfite salt may be selected from sodium, potassium, or ammonium bisulfite, or mixtures of such bisulfite salts. Sodium bisulfite is a convenient and desirable reagent. Based on the total composition, the bisulfite salt may be used within the range from 2 to 12% by weight, such as a concentration of about 8.0%. The bisulfite salt should be fully dissolved, and therefore should not be employed at or above its solubility limit. 
     In accordance with the present invention, the principal swelling agent for use in combination with the bisulfite-containing detergent solution is N.N&#39;-dimethyl urea. No equivalent for this specific compound has been found. Further, the amount of the dimethyl urea should be limited. More specifically, the concentration based on the total liquid composition should be within the range from 2 to 12% by weight, such as a concentration of about 5 to 5.5%. 
     As an auxiliary swelling agent, there may be optionally incorporated a minor proportion of a hydroxyalkyl solvent. For example, hydroxyalkyl liquid compounds such as propylene glycol, glycerine, or hexylene glycol can be used. Alternatively, or additionally, lower monohydric alcohols can be used, such as ethanol or isopropanol. More generally, the preferred class of auxiliary swelling agents comprises water-miscible hydroxyalkyl solvents containing from 1 to 3 hydroxyl groups and from 2 to 6 carbons. The amount of the hydroxyalkyl solvent can range from 2 to 25% by weight based on the total composition, such as about 5%. 
     As indicated, it is also desirable to incorporate one or more cationic hair conditioners. Such agents are well known in the cosmetic art. For example, a compound such as isostearyl amido propyl morpholine lactate may be used. This is available as Richamate ISML from Richardson Co. Other fatty quaternary conditioning agents can be used, or cationic polymers having conditioning action, such as the water-soluble cationic cellulose resins. Such conditioning agents are available commercially as Polymers JR (Union Carbide Corp., New York, N.Y.). Further, a combination of such cationic conditioning agents can be used. All of these agents have the property of being substantive to the keratin of hair. Where the cationic conditioning agent employed is not compatible with an anionic detergent, the detergent base should be selected to avoid anionic-cationic reaction. Only a small amount of the cationic conditioning agents need be incorporated, such as from 0.5 to 3.0% based on the weight of the total composition. Typically, a combination of cationic conditioning agents in a combined amount of about 1 to 2% will be advantageous. 
     Other ingredients may also be included in the composition for commercial purposes, such as a preservative, perfume, etc. Any of the standard preservatives can be used, such as methyl or propyl paraben, formaldehyde, and the like. Usually, these minor ingredients will comprise less than one percent by weight of the composition. 
     A preferred formula is set out below. It will be understood that water is added to provide the balance of the parts by weight. In general, the amount of water present may range from about 60 to 80% by weight. 
     
         ______________________________________Preferred FormulaPrincipal Ingredients  weight %______________________________________Bisulfite salt         6.5-8.5N.N&#39;-dimethyl urea     3-8Amphoteric detergent   6-15Hydroxyalkyl solvent   3-10Cationic hair conditioner                  0.5-3.0Water                  g.s.______________________________________ 
    
     The pH of compositions prepared in accordance with this invention should be adjusted so that they are mildly acid, for example, a pH in the range from 4.0 to 6.9. Preferably, however, the pH is adjusted to a pH within the range from 6.0 to 6.6, thereby minimizing bleaching of the hair as well as alkaline hydrolysis of the hair. Any standard base can be used for adjusting the pH, such as sodium or potassium hydroxide. Where the bisulfite is added as sodium bisulfite, it is believed that the most desirable base is ammonium hydroxide, thereby providing both ammonium and sodium ions in common with the bisulfite ions. 
    
    
     The present invention and the results which can be obtained therewith are further illustrated by the following examples. 
     EXAMPLE I 
     This example is intended to illustrate the best mode of practicing this invention as presently known. A liquid composition for increasing hair body is prepared in accordance with the following formula. 
     
         ______________________________________Specific Formula(pH 6.0-6.4).sup. (1)Ingredients            Weight %______________________________________Sodium bisulfite       7.88N . N&#39;-dimethyl urea   5.20Cocoamidopropyl betaine.sup.(2)                  30.00(30% in H.sub.2 O)Propylene glycol       5.00Cationic conditioners.sup.(3)                  1.60(active basis)Preservative.sup.(4)   0.20Perfume                0.60Water.sup.(5)          q.s.______________________________________ .sup.(1) Adjusted by adding 28% NH.sub.4 OH. .sup.(2) Chemadene Na 30, Richardson Co., Lemont, Illinois .sup.(3) 0.60% Polymer JR 30M (Cationic cellulose resin) Union Carbide Corp., New York, N. Y.; and 4.00% Richamate ISML (isostearyl amido propyl morpholine lactate, 25% in H.sub.2 O), Richardson Co., Lemont, Illinois .sup.(4) 37% formaldehyde .sup.(5) Added to bring total formula to 100% (approx. 46.6%) 
    
     For the purpose of increasing hair body, the foregoing composition can be advantageously employed as follows: 
     (1) Shampoo about 0.5 ounces of the composition into wet hair, and rinse the hair with water. 
     (2) Apply about 0.5 ounces of the composition, and leave on the hair at room temperature for about 15 minutes. 
     (3) Rinse the hair thoroughly with water to remove residue of composition, and then dry the hair and style as desired. 
     The foregoing procedure is preferred for the first treatment of the hair. For subsequent treatments, the same procedure can be used, except that in step 2 the composition is left on the hair for five minutes. 
     More generally, the composition may be applied to the hair in a sufficient amount to coat the hair and left thereon for from 3 to 20 minutes, and then rinsed out of the hair with water. This treatment can be repeated at intervals of from 5 to 20 days, that is, the treatments are preferably spaced apart by at least five days. Preferably, the composition when applied is massaged into wet hair, thereby promoting the distribution of the composition over the hair. 
     EXAMPLE II 
     Using the composition of Example I, the swelling effect on hair fibers was studied. The data obtained is summarized below in Table A. The procedure used was as follows: 
     Cut the hair fibers 3 in. long. Glue 3 fibers parallel to each other and about 2 mm. apart on the slide. Mount the fibers securely with tape at both ends of the slide leaving about 2 mm. open at the center for measuring the diameter of each strand. Using a Bausch &amp; Lomb Laboratory Microscope with standard 10X eyepiece and an eyepiece scale, before treatment, focus the fiber under the microscope with 43X objective, 0.65 N.A. Record the reading on the eyepiece scale. Then treat the fibers as follows: (1) Apply a drop of the test composition on the fibers and cover with a cover glass. Set the slide on a hot plate @ 37° C. for 15 minutes. Using a wash bottle, rinse thoroughly with deionized water. Dry the fibers for 5 minutes with the aid of an electric blow-dryer. Again, measure the diameter under the microscope. (2) For subsequent treatments, repeat the same procedure, but leave the test composition on hair for only 5 minutes instead of  15 minutes. The % swelling is calculated as: 
     
         % Swelling=(B-A)/A×100 
    
     where A equals the diameter of hair before treatment, and B equals the diameter of hair after treatment. 
     
                                           TABLE A__________________________________________________________________________PERMANENT HAIR SWELLING OBTAINED WITH EXAMPLE I COMPOSITIONNumber of Treatments       0  1    2    3    4    5    6__________________________________________________________________________       56.33          61.33               66.33                    68.00                         75.33                              76.33                                   77.0       51.66          54.00               56.00                    56.66                         57.33                              58.33                                   59.0       52.00          54.00               58.00                    58.66                         59.33                              60.66                                   63.0Diameter of 50.66          52.66               53.66                    56.00                         57.00                              58.00                                   58.66Hair       23.66          24.33               25.33                    25.66                         26.50                              27.16                                   27.16       35.66          37.00               38.00                    39.00                         39.66                              40.16                                   40.16       52.66          55.00               56.66                    58.33                         59.33                              59.33                                   59.33Average     46.09          48.33               50.57                    51.76                         53.50                              54.28                                   54.90% Swelling     4.86%               9.72%                    12.30%                         16.08%                              17.77%                                   19.11%__________________________________________________________________________ 
    
     EXAMPLE III 
     The loss of hair tensile strength with repeated treatments using the composition of Example I was studied, using an Instron Break-Strength Instrument (Instron Engineering Corp., Canton, Mass.). For comparison, a commercial waving lotion was included in the test, the lotion containing ammonium thioglycollate as the principal active ingredient. The data obtained is summarized below in Table B. Table C represents values computed from the data of Table B, the numerical values for break strength as shown in Table B being converted to percent loss of break strength. The procedure used was: 
     Preparation of Samples 
     Cut the hair fibers 4 in. long. Weigh 20 fibers individually and record each weight. Tape one end of each fiber and label it 1-20. Place the hair in a Pyrex petri dish and treat the hair as follows: (1) Apply 1 gm. of the test composition on the hair and place it on a hot plate @ 37° C. for 15 minutes. Then rinse the hair thoroughly with tap water. Air-dry at room temperature. Determine break-strength by the Instron Test Instrument. (2) For subsequent treatments repeat the same procedure on another set of 20 fibers, but leave the test composition on hair for only 5 minutes instead of 15 minutes. Weigh another set of 20 fibers to serve as the control (untreated), and determine break-strength likewise by the Instron Test Instrument. 
     Break Strength Determination 
     The prepared fibers of 4.0 inch lengths are weighed to the nearest 0.01 mg. They are then tabbed with white tape and numbered. 1.5 inches of each end of the fiber is then mounted between two layers of transparent tape and equilibrated in a constant humidity environment set at 50% R.H. overnight. The fibers are mounted on the Instron so that the center 1.0 inch of the fiber remains exposed between the jams (clamps) of the instrument. The fibers are then pulled to break under the following conditions: 
     
         ______________________________________Gage Length:         1.0 inchCross Head Speed:    2 inch/min.Cell:                BChart Speed:         10 inch/min.Load:                200 grams______________________________________ 
    
     Calculations 
     The weight of the fiber is used to calculate the volume of the fiber V=Wt. (mgs)/fiber density assuming a constant fiber density of 1300 mg/cm 3 . 
     The cross sectional area of the fiber is then calculated from the volume, assuming a uniform cylindrical shape for the fiber, as follows: ##EQU1## 
     For simplification, a value of 7566.5, derived from the proceeding equations, times the fiber weight (mgs) gives the cross sectional area in microns squared (μ 2 ). The force at the breaking point of the fiber in grams divided by the cross sectional area then gives the break strength expressed as gms/μ 2 . ##EQU2## 
     
                       TABLE B______________________________________LOSS OF TENSILE STRENGTHWITH REPEATED TREATMENTS     Number of TreatmentsComposition None      One      Three    Six______________________________________Waving Lotion.sup.(2)       .0287.sup.(1)                 .0285    .0233    .0198Formula Ex. I       .0287     .0274    .0275    .0249______________________________________ .sup.(1) Break strengths in grams per square micron of crosssectional are .sup.(2) Commercial waving lotion containing ammonium thioglycollate as active ingredient. 
    
     
                       TABLE C______________________________________COMPOSITION OF DATA OFTABLE B ON BASIS OF PERCENTLOSS.sup.(1) OF TENSILE STRENGTH      Number of TreatmentsComposition  One        Three      Six______________________________________Waving Lotion        0.697      18.815     31.01Formula Ex. I        4.530       4.180     13.24______________________________________ ##STR1##